Investigating the process quality there are formed modules, then
their typical and ideal outputs will be discussed. Then 'the blackboxes
will be opened' and each module will be analysed and newly designed.
Process Modules And Their Specific Goals
The process can be separated into four phases with respect to the major task of each phase: auto-selection, presurgical selection, surgery and postsurgical treatment. A patient undergoing Refractive Surgery should proceed through all these phases. However, at the borders of each module there is a big loss of (potential) patients. The reasons of dropping out of the scheme differ in each patient. Nevertheless there are similarities in the reasons why patients choose to drop out of the process at the various stages. The aim of process analysis is to become aware of these motivations and to improve the process so that these losses only occur when it is to the benefit of the patient.
In the short-sighted view of the clinic, the aim would be to persuade as many patients as possible to undergo surgery to produce higher short term profits. However, many of these 'persuaded' patients would be disappointed after surgery and not recommend the surgery, even less the institution to others. In the long run the interests of the clinic and the patients will rather be the same.
The task of the clinic will be to select as many patients for surgery who will be happy with the results after surgery and convince only these patients to undergo surgery. Therefore the four phases need to be structured consciously to induce and control best patient selection.1
Analysing the borders of each phase in a top down approach will reveal the actual status of uncontrolled patient selection. Requirements for a controlled conscious patient selection process can be developed. This will be done by defining general policies and classes of outputs in each phase. In a next step the blackboxes will be opened and each phase will be analysed more closely. A process model for all phases will be developed to fulfil the built-in requirements of each phase. The phase of presurgical selection will be the most in focus, as it strongly defines the possible outcome of surgery and patients attitude for undergoing surgery.
Before the patient wants an appointment asking for surgery he has already selected himself from many other emmetropic patients who are not interested in surgery. This individual choice is most fundamental and should never be forced. Disappointment and complaints would a rise, if patients are operated on against their will or due to false information. The patient therefore will make an appointment according to his general attitude towards surgery, his personal situation and the given information, as shown in the diagram. His general attitude will be influenced most by the family's education, a country's culture and the zeitgeist. His personal situation is characterised by many variables, such as age, profession and personal environment. The information he has received about Refractive Surgery is the only variable which can be controlled in some way. Information about Refractive Surgery can range from the results of operated friends to mass media and official brochures from ophthalmologists' societies. In the long run, this information will correlate strongly to the satisfaction and results of former patients.
The next phase is the presurgical selection, this is to say when the patient makes an appointment to see whether he is suitable for surgery. It is in this phase that he comes into contact with the clinical institution for the first time.
The aim of this phase should be to match the technical possibilities of surgery with the patient's individual requirements. Surgery will be a good choice when the technical best matched outcome will be above the individual's expectations. Each patient will have his own personal expectations which will result from his situation. In accordance to Meyer this will be the sum of all the provable and the subjectively true judged beneficial expectations [Chapter 3]. An integrated selection process will only produce three types of patients. Patients who can not undergo surgery for medical reasons, patients who should not undergo surgery because of a frustrating difference between their expectations and the expected outcome, and convinced patients with best matched individual surgical parameters. The three outputs in figure 30 show this ideal situation.
However, today's common presurgical selection phase is focused only on the medical point of view. The patient is passed through all the necessary examinations. After this time consuming "torture" he will be told whether he can undergo surgery or not. The technical parameters of the surgery are usually not matched with the personal situation of the patient. 2 In taking the decision of undergoing surgery the patient does not get help or sufficient information as to whether the expected outcome will meet his expectations of surgery. Many patients will be somewhat indifferent to surgery because they lack information. Moreover, the lack of information will provoke that any experienced observation during the presurgical examination will hold as a reference information to the patient. Again, the fact that any eye surgery is unpleasant will support any unpleasant experience and finally hold off many indifferent patients from surgery. Excess time spent waiting will frustrate any patient's attitude and give more opportunity for making unpleasant observations. On the other hand, an ophthalmologist might use his authority to talk the patients over to surgery. Depending on the mood of the patient he might sustain this manipulation. Patients are thus persuaded, are more likely to be disappointed than well informed patients. Today's patient selection is therefore far from the achievable best patient selection. The following picture demonstrates the common continuum of patients after presurgical selection. The actual amount of patients undergoing surgery might be similar to a well controlled selection but with much less satisfaction.
The surgery module can be analysed and designed in two complementing ways. Firstly, in optimising the process as to how the patient passes through the different stations. Secondly, an analysis of the detailed surgery and its recommendations for the best handling of the surgery. The aims of the former should be to shorten the total stay of the patient and to improve contact with and integration of the patient. The latter will take advantage of the long Barraquer experience in handling this surgery. Moreover, the development of organisational hints to allow statistical quality improvement will be under focus.
The postsurgical module can be divided in two different phases: small ophthalmic control the day after surgery and complete control one week after surgery. The latter should be repeated three, six and twelve months after surgery. Depending on the culture, many patients will not turn up for these controls if they have to pay for it. The costs of post control should therefore be included in the price of surgery. The process of examination will be similar to the presurgical selection process. Patients should also be asked systematically about their subjective sensations. When mixing operated patients and potential candidates in controls, one should be aware of the interactivity between the different groups. Any unsatisfied patient will easily affect the potential candidate's opinion. A 24 hour accident service should be provided in case there are problems with the flap's interface. If post control is done by a different institute, adequate payment rules should be arranged before surgery to guarantee best service. If post control is decentralised frequently, proper wide area feedback channels should be settled for quality control.
Process Analysis and Design
The modules will now be investigated in detail and as a consequence new process modules will be designed. The auto selection phase will not be further detailed, as aspects of this phase have already been discussed in 6.1.1. The notation which will be used is common in a discrete simulation of processes. The advantage of this notation is that it is easy to understand and the basic actions of the process carrier, e.g. patient, is visible. Given the fact that this paper is addressed to ophthalmologists and the fact that the complexity does not require a more complicated notation for a new organisational design should strengthen this decision. However, for the implementation of an information system of new design, a different notation for modelling will be necessary. This can be an integrated tool as the ARIS-Modeler or a paper based on single sight notation like for the ERM notation. See [Kus94] for the selection of an adequate notation when planning an information system.
The notation in this paper uses different symbols for static and dynamic elements. The two dynamic elements are the process carrier and the transportation unit. The process carrier is symbolised by an ellipse with a black top as shown in (fig.32). The history of the patient could be defined as a second process carrier. However, where ever the patient will be examined the history must be at place. Additional modelling of the history would be somewhat redundant. The second dynamic element, transportation, is represented by a rectangular symbol with a cut edge. Although the patient will move himself he still must be co-ordinated and organised when changing between consulting rooms. The history needs to be co-ordinated and physically transported between consultation rooms.
The static elements are the stations (consultation rooms), the repositories (waiting rooms) and the paths (floors) which the patient has to pass through. The stations are represented as rectangular symbols, repositories as a half-moon and the paths as arrows. When simulating a production process different kinds of rules exist referring to access, capacity and time spent at each station. Many of these rules result from the passive nature of the process carrier and the transformation of different process carriers. For our purposes it will be sufficient to concentrate on the basic structure of the process, on time variables and some access rules.
After auto selection the interested patient will make an appointment with the clinic of his choice. The kind of telephone manner the patient receives will give an immediate image of the institution and strongly influence the patient's attitude. Moreover, this situation could be used to get the first information about the patient. Usually the conversation is limited to finding the first free spot on the calendar which suits the patient. Instead, the patient could be asked why he wants to consult an ophthalmologist. In accordance to this information the patient could be immediatly categorised. New patients applying for Refractive Surgery could be united to certain days when all resources could be 'lined up' for the benefit of the patient, and further information such as age could be collected. On the other hand, the patient could be informed about certain circumstances.
For instance, that he should not wear contact lenses for two weeks before consultation and that he should bring some sun glasses, as his eyes will be sensitive to light for two hours after the examination. It should be mentioned that receptionists will need some special training for this conversation. Depending on the amount of phone calls, the published phone numbers could already guide the patients towards specialised receptionists to improve the conversation and to minimise stressing phone call co-ordination. The following picture summarises the discussed situation of answering to telephone calls, showing the traditional way on the left and the newly designed approach on the right.
On the day the patient enters the clinical institution, he will first come into contact with the receptionist. In most institutions he will than start a long journey passing through various medical examinations. He might be lucky, and be able to take all the examinations on one day, however, often he is not able to do this. Maybe, he did not stop using contact lenses, or maybe he was not informed how much time examinations will take, or maybe the organisation does not allow for quick examination. The following picture shows the long journey the patient has to take. The sequence is typical, but some examinations might follow a different sequence. Before the patient is examined by an ophthalmologist, he will pass a basic vision examination so that the ophthalmologist gets a quick overview, without wasting his time for time consuming measurements with each patient. The ophthalmologist will than look for general contraindications before the patient undergoes more detailed examinations. The following two examinations are of a similar nature. They only take a few minutes each and the amount of time for each patient examination is almost the same. However, due to historical development they might be located in different rooms and even on different floors. In reality a patient might spend more than an hour undergoing these two exams.
In the worst scenario he might need to leave the clinic because the person in charge is not available. Even the institution itself has to spend more staff and resources in co-ordinating the patient and his history, than in actually doing the exams. Nowadays these examinations can easily be done by anyone with half an hour's initial training. Locating the equipment in one room with additional direct access to the optometric consulting room would allow for efficient and quick consultation. Depending on the amount of patients, the exams could be done by one or two optometrists. In any case the history can be passed on in handshake manner without additional staff, possible equivocations or time delays. Usually the FIFO (first in/first out) principle will be used. If patients of different consultation lines need to pass the same examination different rules might be set up in accordance to the actual amount of patients. The patient will then be prepared with drops for undergoing cycoplexic vision examination. Myopic patients must also undergo a retinal check to minimise the risk of possible retinal surgery with a recently operated cornea after the LASIK surgery. The latter examinations require drops and can only be done at the end of all examinations. A final consultation with the specialised ophthalmologhist in Refractive Surgery will end the process. He will check the examination results and tell the patient whether he will be a good patient for surgery.
The total time needed for the examinations is about an hour (57min) on average. However, the patient will most probably spend the whole day in the institution; spending about 7 hours in waiting, looking for his way around the institution, asking secretaries, disrupting other consultations and making phone calls to cancelling his other important appointments. During all that wasted time the patient will be constantly observing what is happening around him. His positive attitude torwards surgery might decrease every minute. Speaking in the words of Meyer, most institutions do everything to decrease the needed integration of the patient. The contact potentials are close to zero and the consumed process quality is below any degree of satisfaction.
Of course, 57min is somewhat unrealistic. However, the waiting time should not exceed the time of actual consultation. A two hour stay for undergoing all the examinations is possible, even after increasing the quality of the examinations.
Referring to the discussion in chapter 4 about different types
of organisations in services, a group/line organisation seems like
a must for a customer orientated approach. A tayloristic organisation
in ambulant medical service only makes sense when the variety of
patients is high and the costs of having unused resources are of
significance. For our situation, in an institution which is highly
specialised in Refractive Surgery, the organisation and the management
of patients needs to be designed for these requirements. The universal
workshop style may allow a flexible response to any kind of patient
and for any kind of examination at any day but to the cost of slow
and bureaucratic management. A group/line organisation can be flexible
enough to respond to the patients by allowing a much quicker and
better service. The following sketch will be an approach to replace
the old tayloristic organisation.
The sequence of exams has not been changed nor the expensive time the ophthalmologist spends with the patients. However, the disruption of the patient flow has been cut from eight to only two waiting rooms. If the patient has to wait 20 minutes in each waiting room he would have undergone all examinations in two hours! There are actually only two major changes which count for this six hours time reduction.
First, all corneal measurements are done at one station so keratography, topography and the cycoplexic vision examination are done in one room. Staff would be organised according to the amount of patients as mentioned earlier. Besides, the time saving aspect for the patient, the integration of this work will make co-ordination much easier. The history will be passed on without additional transportation or co-ordination as everything is done in line and at the same location and this will reduce the risk of losing the histories. If the mentioned optometric station is even located close to the ophthalmologist the contact potentials of the clinic grow even more. Topography and keratography should be in line but should be slightly separated from manual vision examination to allow flexibility for other patient types to 'intersect' the station.
Second, the reception and the first optometric measurement have been integrated to one station. The reception should not be seen as an anonymous information desk. Instead it is moment of the truth, where the patient gets his first impression of the clinic. Moreover, to guarantee best co-ordination the reception must get somewhat involved in the problems of the patient. Instead of having many untrained staff, patient contact and integration would be improved by fewer but trained staff. A managing crew of a well experienced receptionists directly working together with an optometrist could give the patient the best guide to the institution. New patients would automatically receive the first vision examination. Patients applying for Refractive Surgery would be informed personally, and be equipped with a hand-out to prepare them for their final consultation with the refractive specialist. This will ensure best information exchange and induce efficient "to the point" consultations. As the expectations of the patient and the expected outcome of surgery are matched up, there will be only two groups of patients at the end of the selection process: good candidates undergoing surgery and candidates not undergoing surgery. The indifferent patient is omitted.Surgery
Process of the Patient
Figure 34 follows the approach that the patient is the process carrier. The patient starts the process of surgery before entering the actual operating theatre. When he turns up, he begins at the reception, where the scheduled surgery is confirmed. If there are any delays can wait now, still being comfortable in his clothes. He then has to undergo the presurgical preparation, which mainly consists of changing his clothes for surgery. He will be given some kind of tranquilliser, if he seems very nervous to ensure sufficient integration. Delays above 15 minutes should not occur at this stage, the ability of integration could suffer due to the missing respect of the patient. After surgery he needs to recover about two hours, during this time a first control by the surgeon is taking place. He then will go home by taxi or be taken home by friends.
It may be surprising that most steps are in one box, even though the steps take place at different locations. However, all programmed patients for LASIK surgery have to follow this path. Taking out the buffer times and waiting rooms simplify this path. The history of the patient needs to be present only in the operating theatre. It makes things easier to have all histories of the expected surgeries at the reception to avoid delays caused by having to locate missing histories. After the patient has checked in the history should be brought to the surgical room. The optometrist handling the programming of the laser should then be responsible for the patient history. It is obvious that operational efficiency becomes greater, if rooms are located close to each other. A schedule for the surgeon crew should be generated either on a white board with a felt-tip pen (never dusty chalk) or on an on-line information system to be able to quickly respond to changes.
Detailed Steps at Surgery
Surgical procedures even of the same technique vary depending on each surgeon. It is true that
a surgeon will produce his best performance with his personal technique. However, disregarding the personal preference of one specific technique, there exists a best practise technique, that is to say a method with the best outcome and a quick learning curve. The LASIK techniques of the Colombian surgeons, owing wide experience, are very similar. Their investigation and operational experience gained to high patient numbers have already evolved best practise techniques. The North American and the European surgeons, trying the LASIK surgery, focus much on additional procedures as for instance wearing contact lenses after surgery. However, the author believes that any additional procedure will bear a potential risk and therefore should only be done, if real improvement for the patient is expected.
The outcome of any LASIK surgery depends very much on the skills of the surgeon. Any academic discussion about the best anaesthetic eye drops will be wasted, if the surgeon generates epithelial ingrowth because he does not know how to use two cannulas to avoid this.
The following procedure is based on the actual approach in the Barraquer clinic that is to say the observation of more than seventy LASIK operations by different surgeons at this clinic during 1996. The author is not an ophthalmic surgeon, however his observations were underlined by detailed discussions in the native language of the surgeons (Spanish). Each surgeon had carried out at least 700 hundred LASIK surgeries before 1996, moreover they even included the experience of former keratomileusis techniques as well as other refractive techniques.
The following can not take the place of good training, but it can give an idea of what will be important at surgery. Surgery is being done with the Chiron microkeratome, the lasers used are Schwind, Visx 20/20 and Visx Star. The steps of the basic procedure do not depend on the kind of correction. The steps however, do depend to some extent on the laser and certainly on the kind of microkeratome used.
Although the surgeon sets his surgical crew, the steps are listed in the areas of responsibility of each member of the surgeon crew. The steps of the surgeon are on the left, those of the trained technician taking care of the computer are in the center and the steps of the assistants are on the right. The technician should be a trained person who knows the handling of the laser perfectly. He should be trained by the laser manufacture to ensure best handling and even improve the information flow between the laser manufacturer and the clinical institution. Although he does not need to be an optometrist, a well trained optometrist supports the responsibility of the surgeon and improves the quality of surgery. Reading the bold words give a quick overview of the whole process. Underlined words show the instruments needed to perform the surgery.
surgeon: trained technician: assistant(s):
1.welcoming of patient by surgeon crew
2.complete name check (asking first name and surname), identification!
1.entering general patient data into computer
1.patient is helped onto the patient bed
fixation of head with air-pillow
first sequence of anaesthetic drops
covering of the patient
contralateral eye is to be covered with a protector (e.g. metallic cover) to avoid any pressure of the surgeon and allow that only the eye operated on receives light to improve fixation
5.centring the patient bed, the patient and the patient head
6.verification of scheduled surgical parameters by surgeon with trained technician
anticipated target refraction in respect of the potential quality of the eye and the patients priorities in quality of vision have already been scheduled in final examination with the patient. (See 6.2 and 6.3.)
7.entering ablation profile parameters
8.placement of eyelid speculum
9.application of second sequence of anaesthetic drops
10.marking the cornea with a simple needle tip making a very small linear erosion without any indentation(to be able to find the flap in case of a complete cut; a four radial marker is too risky: danger of damaging the cornea, especially if used before the microkeratome cut))
11.handling the suction ring
placement and centring suction ring
checking of suction with Barraquer applanation tonometer: higher than 65mm Hg
checking the diameter of the disk with the applanating lens
if diameter is too small (big)the suction ring needs to be changed
and the stopper of the microkeratome to be adjusted to obtain the hinge as wanted
doing a retreatment of LASIK the diameter should be somewhat (0.5mm) smaller than the original, if the original flap is not used anymore (after six months of first surgery)
12.handling the microkeratome
testing of the automatic and smooth blade movement before the real cut
adjust the stopper to the diameter (decide what size of hinge you need)
a few water drops onto the gears and the cornea for perfect movement
setting of microkeratome on track gears
forward cut until automatic stop
careful observation at the time of backward cut to notice any abnormality of the disk
if disk is cut completely, it needs to be located and instantly stored in a plastic antidessication chamber
if stroma is open and there is any delay, it should be covered with a plastic cap
if cut has major irregularities surgery has to be stopped.
if the cut is very thin, and with minor irregularities surgery can be changed to superficial PRK or stopped and repeated after three months
if there is bleeding in the periphery (often when diameter is greater than 8.5mm, soft contact lens wearer) it should be taken with the sponge, next patient needs newly disinfected microkeratome!!!)
13.eye is centred, that is to say the patient bed is shifted
14.disk is folded to nasal side: carefully, using always a new instrument to avoid epithelial ingrowth
15.patient is asked to fixate the laser
if patient can not fixate or hold center, eye needs to be held with forceps in the outer corneoscleral limbus
17.disk is now folded back
one cannula is used to fold back the flap (only contact with epithelial surface of flap)
use of another instrument for the stromal interface: usually irrigation cannula
after flap is returned a good irrigation is necessary to help a complete and smooth replacement without provoking wrinkles, also ejecting any foreign particles that could remain between the interface
flap is smoothly pushed onto the stroma with a sponge (e.g. Merocel) always from hinge (nasal) direction, edge of disk is dried out with the sponge to ensure good adhesion of the flap
check of good adhesion by depressing corneal limbus, stress lines must radiate into the flap
18.eyelid speculum is taken out
19.patient is asked to blink and any displacement of the flap is observed (three times)
20.drops are to be placed
mydriasis with cycloplegic agent
21.eye is covered with plastic cap which is being filled with cushion to keep eye closed for an hour
22. surgeon asks the patient to never touch and rub his eyes
no swimming for 1 month
no make up for three months
take care for make up after three months
23.patient is helped into the wheel chair
24.patient is brought into the recuperation room
Figure 48: Detailed Steps at Surgery
Some readers might be surprised why the suction ring is taken off at the time of ablation. Waring and Ruiz prefer to leave the suction ring placed during the time of ablation. Waring leaves the suction ring placed without suction [SWM+96], Ruiz leaves the suction during the whole time of ablation [Rui95]. Both use the suction ring to fixate the eye. However, if best fixation can be obtained by the auto-fixation of the patient, it should be preferred. The disk can easily dry and stick on the metal of the suction ring. The suction during the whole process of ablation strains the eye. However, if using the suction ring for fixation there should be suction at all times while the flap is folded back to ensure that the flap is not damaged by sudden movement of a loose suction ring. Employing this "Ruiz" method it is helpful to absorb any moisture above the suction ring at the time of ablation with a cotton swab. The experience with the VISX and the Schwind laser has shown that auto-fixation is fine even in LASIK, that is to say even seeing without the flap. If a patient can not hold and center his eye towards the fixation laser, the position of the eye can be held and controlled with a forceps in the peripheral limbus.Postsurgery
There are two different types of postsurgical controls: a small ophthalmic control (fig.37)on the day after surgery and four complete controls (fig.37)during the first year. The first complete control takes place one week after surgery, then after three, six and twelve months.
The day after the surgery only a ophthalmic control with rough optometric measurements is employed. Rapid improvement allows first stable optometric measurements after one week's time. The examinations are very similar to the presurgical control. Figure 37 shows a computer assisted consultation about subjective quality indicators by the reception staff. The subjective quality indicators are listed in 6.3.5. and have been discussed in 6.1. The information is essential to further improve the surgery on the patients. The data must be collected by an information system to keep things simple. Obtained data can then be easily aggregated and compared even with the clinical quality indicators to further improve surgery and detect any undesired "offsets" in the operating theatre as early as possible.
However, usually there are no real complications and the benefit of these examinations is rather for the experience of the clinic and future patient than to the actual patient. Depending on the culture and education of the patients many of the happy patients will not turn up for these examinations. However, to ensure total quality in Refractive Surgery the examinations after surgery are essential. Moreover, only a complete data base will allow highest quality standards.
The patient has to be encouraged to return for postsurgical control according to the customs and behaviour of the patient. The general level of patient's reliability, and personal effort to visit the institution are the given variables. Long waiting times will certainly support the absence of many patients who are willing to undergo the postsurgical examinations. Directly charging the patients for each postsurgical examination will also hold off many patients. Only if patients do not to have to wait more than 30 minutes and spend a pleasant time in the institution they will turn up for postsurgical control. Patients should already have paid for their postsurgical examinations before surgery, that is to say the fee for surgery should include the postsurgical controls. If the patient participates in all postsurgical examinations he should be rewarded with a percentage of the total fee paid for surgery. This even is legitimate as the patient helps the clinical institution to improve their quality standards.
In some cases the patient's vision should be trained. Patients have to get used to their 'new eyes'. The changed refraction makes it necessary to readapt to emmetropic conditions. Training of binocular vision is helpful. Presbyopic patients who decided to split up their vision have learn to work with their near sighted eye and to use their dominate eye only for longer distances.3
Potential Quality of Clinic
Now already knowing the true quality characteristics, the potentials of the patients and the process itself, the needed characteristics of the clinic will be discussed. Of course, many aspects of the clinic have been touched previously, as in many cases the limitations of the used technique define the potentials of the patient. Nevertheless, knowing the true quality characteristics, then applying the Model of Meyer and leaving the potentials of the clinic till last will automatically provoke a focus on the bottle necks and difficulties. Intelligent management of these bottle necks and difficulties will be the only valid potential of the clinic. The used resources form a major part of this potential. However, it is more matching the needed characteristics perfectly, rather than a blind fixation on the latest equipment that forms the real potential.
Specification and Contact
The potentials of general specification and contact are reflected in how the process is designed to meet the needs of the patients. The specification refers rather to the organisational structure of the institution to allow an efficient handling of the patient. The potentials of contact refer to the ability of the staff to satisfy and manage the patient. Both have been discussed in the design of a proper process quality. However, the experienced process quality should be measured constantly to become aware of organisational bottle necks. The following list can be the base for a questionnaire to control specification and contact.
Discussing all the equipment needed to perform surgery can not be included in this thesis. Instead the focus will be on the most important instruments to perform LASIK, the microkeratome and the laser. Again, we will only focus on the bottle necks and difficulties of these instruments and finally some hints on other equipment is given.
The usage of the microkeratome is the major difference for the surgeon doing LASIK in advantage over PRK. The history of microkeratomes is most connected to José Barraquer and most microkeratomes in use today take advantage of his long experience. Although there exist more than six commercial microkeratomes, most LASIK surgery is done with the "Automated Corneal Shaper", it is an improved commercial version of former Barraquer microkeratomes, designed by Barraquer's protégé Dr. Ruiz and sold by the Chiron company. The Phoenix (Peschke) and the Schwind microkeratome are somewhat similar. This is not surprising as their roots of design also started in the Barraquer clinic of Bogota [Koe96] [Els96]. A different approach is the Draeger microkeratome as it uses a rotating blade instead of a vibrating blade. Before going into details, it is important to mention that until now all microkeratomes are far from being perfect, each having advantages and disadvantages. It is from discussion that any experienced surgeon will 'be best off' with the microkeratome he used most, as each microkeratome has its own learning curve. For surgeons new to the field, it seems impossible to have an idea about what features are essential. Until the perfect microkeratome has been designed, the choice will also depend on the amount of surgery one will expect, as some microkeratomes might be easier to handle than others but be limited to working on standard eyes. The best approach for judging the potential quality of today's microkeratomes will be aware of the essential requirements a perfect microkeratome has to fulfil. This has the advantage of keeping the mind open to any different technology.
However, what is today's best commercial microkeratomes? Regarding the competition of PRK up to 6 diopters, and the fact that for LASIK sterile conditions are required, it does not make too much sense, to decide to invest in LASIK with an easy microkeratome and therefore missing out on many patients who do not have standard size eyes. The microkeratome which can be used even in difficult circumstances is the Chiron microkeratome. However, the suggestion is to use three fixed rings instead of the adjustable ring, dramatically reducing the risk of faults. Their size should be 12.5mm 12mm and 11mm [Bar96]. However, it should be mentioned that the Chiron microkeratome requires a talented surgeon, careful maintenance and sufficient teaching.
The Phoenix and Schwind microkeratomes bare the theoretical advantage that the cut is somewhat smoother due to its zero angle blade. They also allow the surgeon view of the cut at surgery. However, they both fail easily in small eyes. Both are somewhat clumsy and the sudden vibration of the Schwind microkeratome must be handled. The epithelia gets slightly more damaged due to the double suction ring.
The Keratom (Laser)
A general introduction to the excimer laser has already been done in 22.214.171.124. The five most commonly used lasers are Summit, VISX, Schwind, Chiron and Meditec. Only the Summit and VISX lasers have been approved by the FDA in the USA for PRK surgery. Not surprisingly, both are US owned companies, the other lasers are of German origin.
Observing the ablation profiles, and analysing the occurrence of unwanted central islands there seem to be two major approaches allowing best uniform spherical ablation without too much unpredictable software fill in. The first approach is using a very powerful laser with a whole field delivery system, this is to say >200mJ/cm2 and a repetition rate of at least 16 HZ. The second approach uses a scanning laser. The advantage is that a much less powerful laser is needed to produce a uniform field without central islands. However, technology of the delivery system needs to be much more "intelligent".
Future potentials and the status quo of both approaches are listed
Figure 48: Potentials of Laser Approaches
Although there exist many important requirements to use the laser efficiently, until now major focus has been on the ability to ablate all types of regular ametropia. Very good results are obtained only in plane myopia, good results in myopia with compound astigmatism: somewhat satisfactory results in hyperopia, but only poor results in hyperopia with compound astigmatism. Moreover, much of today's ablation software even allow the superposition of single hyperopia ablation with additional astigmatism ablation, which has only been designed for compound myopia. First, tissue will be taken to steepen the cornea (hyperopic correction) then even more tissue will be taken to correct astigmatism. Results are very poor. Instead, hyperopic astigmatism correction needs ablation, which steepens the cornea less in respect to the angle of the astigmatism in the first place. Today, it is preferred to express the astigmatism in negative formula as induced aniseikonia in spectacles is minimised. However, for the ablation, it will be very different, if a patient is treated +4sph -3.00 cyl/00 or +1sph +3 cyl/900. It should be obvious that the second notation is the preferred choice in Refractive Surgery respectively describing the situation above.
Figure 48: Notation for Refractive Surgery
However, what will be an easy rule for the ophthalmologist to follow? If sign of sphere and cylinder are equal (taking zero as needed) the notation will be correct for Refractive Surgery. If this is not possible, this is to say in case three, absolute notation should be preferred, instead of the common differential cylinder notation.
Nevertheless, changing the notation either from + to - cylinder notation is a source of errors, even for the experienced ophthalmologist. Working always with absolute notation as recommended in the third case would overcome this problem. In the mean time, the algorithm of the ablation software should automatically accept all notations and calculate the preferred notation for Refractive Surgery, to relieve the ophthalmologist of error provoking calculations. However, after the calculation, the software should advise the ophthalmologist about the calculation and propose the general type of correction, this is to say the category of correction.
Besides these essential requirements, there will be requirements
precision, low possibility in fatal error and user efficiency. The important criteria is listed below
Figure 48: Requirements on Excimer Lasers
None of today's lasers fulfil the essential requirements for a universal refractive laser. It seems that the Schwind laser produces very good results in plane myopia and satisfactory (competitive best) results in plane hyperopia. The VISX and Summit laser seem competitive best in compound myopia and the Chiron laser seems best equipped for the future. Regarding the other requirements the VISX laser seems most ergonomic and the Schwind laser most reliable.
Condition of Operating Theatre
Reminding that corneal tissue is highly watered and that any object in-between the interface of flap and stroma might induce a loss of vision or even epithelial ingrowth, suggest that best atmospheric conditions in the operating theatre are essential.
High temperatures and dry conditions will quickly dry the corneal tissue. The ablation of a dry cornea will be somewhat more profound than of a highly watered cornea. Even more, most lasers vary in power and consistency in relation to temperature and humidity. They produce best results in dry and rather cold conditions. Moreover, the height (less oxygen, less atmospheric pressure) might even influence the amount of ablated tissue. Regardless about the limitations of today's commercialised lasers, there might even exist a best combination of temperature, humidity and height for optimal laser and tissue interaction. However, besides the discussion of a static optimum, it will be even more important to keep conditions as constant as possible. Time in-between the hinged flap and termination of ablation can vary between 1 and 10 minutes, depending on the atmospheric conditions, the corneal tissue can dry out very quickly. The results of the surgery can therefore be very "time sensitive". If precision is a major goal, time sensitivity should be as low as possible. Time sensitivity is lowest in cold and moist conditions with no direct air ventilation. However, respecting sufficient comfort of the surgeon and of the laser itself temperature must be between 160 and 220 C, humidity should be at the upper limit of what the laser unit specification and the surgeon tolerate to be OK.
In addition to superficial PRK, LASIK requires a sterile operation theatre due to intrastromal ablation. Even more important, is a dust free condition, any particle in-between the interface of flap and stroma will reduce quality of vision and might provoke epithelial ingrowth. Dusty outside conditions might require air treatment. If particles are found frequently in-between the interface in the first control after surgery (slit examination), the condition of the operating theatre must be improved.
Besides adequate equipment, the staff and their interaction with the given equipment will be the most determining factor about the surgical success. Strategic personal management will be a major task for best patient satisfaction. The surgery crew with the surgeon at focus, will be discussed in particular.
Strategic Personal Management
The size of the institution will certainly influence the style of personal management. The bigger the institution, the more difficult it will become to manage the personal to achieve best contact potential. However, small client oriented structures are possible even within bigger institutions. After decades of specialising, many parts of labour can now be reintegrated to the benefit of contact and efficiency. This is due to easier use of machinery and information technology. In many circumstances, more work and risk of errors is generated by splitting up a natural workflow into bits and pieces than efficiency is gained through its specification. Excess specialisation not only provokes a lack of motivation and commitment in the staff, in our case where the process carrier is human, it also lowers the integration of the patient. Excluding the necessity of a specialised surgeon crew and ophthalmic staff, all the other staff rather require low specialisation. Staff should be able to perform all types of work occurring in the workflow. From appointment making, word processing to doing different types of exams. In the beginning job rotation will allow a better understanding of the workflow and induce a better integration of work.
For further analysis, staff will be divided into staff generating direct surplus value and support staff. The staff which is generating direct surplus value are the ophthalmologists and optometrists. Today's support staff include administrators, secretaries, nursery and maintenance. Further labour is needed for cleaning and food. These services are often done by external companies. However, this is not for discussion. To obtain best contact potentials and short stay times of the patient integration of work will be a must, allowing a better workflow. On the other hand, it is obvious that the expensive time of the ophthalmologist needs to be saved. The following picture demonstrates the traditional hunting line of work substitution at a typical eye clinic and a modified hunting line. The traditional hunting line shows how the need for efficiency splits up work, the specialised ophthalmologist being the most expensive staff factor, his work being hunted (eased) by ophthalmologists and secretaries. The work of the ophthalmologist being hunted by specialised opticians each doing specific exams. Again, their work is being hunted by nursery or experienced secretaries to save costs. However, the amount of staff is generating its need to be co-ordinated, and each deviation of the workflow is generating error provoking interfaces.
With today's technology opticians don't need to be specialised
so much, trained, they can easily do all types of modern examination
and be efficient at the same time. This new flexibility allows an
integration of work, which is needed to improve the contact potentials
and smooth the workflow of patients. The "patient-doctor interfaces"
can be reduced. The use of integrated information technology allows
a reduction of secretaries. For, instance, using Email, traditional
letter writing, which used to be done by secretaries, becomes rare,
the work is done directly without delegation by the ophthalmologist.
A typical rationalisation of modern work integration. The modified
hunting line of true workflow efficiency takes the possibilities
of new technology into account and is aware of the limits of excess
Less but more efficient support staff, will reduce generation of work and eliminate the probability of errors. However, the more flexible staff structure, especially the higher responsibility of opticians, can cause new conflicts. Sharing equipment must be trained to avoid frustration due to missing communication when the equipment gets broken . For all the shared equipment a general access entitlement must be discussed by the users. Access on-line lists will support responsibility of the equipment.
Savings made from the better use of staff and resources can then be used to improve control of quality. A small but efficient department of statistical process control can be the vehicle to a successful continuous improvement process (CIP) and finding the best direction for any further investigation required.
Once the best outcome for each individual has been defined, the actual result will be influenced most by the specific qualities of the surgeon. His specific qualities can be divided into knowledge, skill and experience. Experience being the most important factor. Learning curves are the most common device for measuring experience. However, how can surgical experience be accelerated without the need for guinea pig patients?
The concept of learning curves goes back to 1936. Wright noticed that in aircraft production costs decreased after each aircraft was built. Further investigations have found typical shaped learning curves for different industries. The Boston Consulting Group further developed this concept including all types of costs even besides production. S- and L-shapes are typical forms of learning curves, as measurable experience develops quicker in the beginning and slows done later on. The x-co-ordinate represents the accumulated experience, that is to say the number of aircraft built, or the number of patients operated on. The y-co-ordinate represents the efficiency. In industry, efficiency is usually referred to by the costs of one conforming unit, assuming that quality is kept constant. In surgery however, efficiency is better expressed by obtained quality, due to the fact that bad surgeries can not be sorted out, that is to say that the costs of defects can not be calculated onto the conforming units. Co-ordinates are commonly logarithmic, regarding rather few cases in Refractive Surgery compared to mass production, the author recommends a non logarithmic approach.
Tavola et all [TCG+94] investigated the learning curve in superficial PRK of myopic patients. They compared UCVA, BCVA, refractive error, haze values and decentration in comparison with the first 160 operated eyes. Except BCVA, all indicators improved with an increasing number of patients, mean results being closer to the target and decreasing ranges. The gain in UCVA dramatically improved after the first 120 patient, in mean and precision; with a mean of 0.54 at the first 40 patients compared to 0.73 in the patients 120 to 160. The mean refractive error improved from -0.88 to -0.26 diopters respectively. Centration steadily improved until the 120 eye, then centration improved dramatically. Decentration (>0.5mm) decreased from 18 % in the first 40 eyes to less than 4 % in the eyes 120 to 160. Haze values improved similarly, although they can not be compared to LASIK. From the data available it can be assumed that the learning curve in PRK is s-shaped, showing slow improvement until about 120 eyes, then having a break through. Unfortunately, their is no data available for the following eyes. The first graph in the following picture demonstrates this situation, as the average quality of the superficial quality improves dramatically after the 120th eye operated on by the same surgeon. Moreover, the range of attained quality decreases with experience as observed in Tavola's investigation.
Trying to transfer this data to the more complicated LASIK procedure,
it will be best to divide the LASIK procedure into the flap making
and the ablation parts. The shape of the ablation learning curve
(top right) will be somewhat similar to superficial PRK. However,
centration will be a little more difficult in LASIK. Although the
patient still can fixate the laser at surgery with the opened flap,
the surgeon does not have the time as in PRK after the flap once
is folded back. The learning curve of the microkeratome (bottom
left) will be rather l- shaped, here the procedure will either work
or not .
The complete learning curve of LASIK (bottom right) will be somewhat steeper in the beginning and also somewhat larger than the learning curve of superficial PRK. The superposition suggests that the average quality will be above the inspection criterion after about 180 eyes. However, sufficient predictability will be reached after the 220th eye. Although these sketches are based on the results of Tavola and the author's own observations in LASIK, it must be mentioned to mention that these sketches are of demonstrative character. To keep things simple only the inspection criterion has been chosen, the assured quality level will be somewhat less rigid and the quality target even more demanding.
However, which indicator will best demonstrate the improvement of experience in LASIK? Absolute deviation from target refraction, relative deviation from target refraction, amount of complications or decentration? Absolute deviation from target refraction seems most impressive, however, the amount of patients will not represent a constant sample of variety in the amount of ametropia, that is to say the deviation from a intended -10 diopter correction will be somewhat greater than from a -2 diopter correction. Relative deviation from target refraction reduces this problem, but is the relation of absolute deviation in respect to target refraction linear? Moreover, once the stage of investigation has finished, it should not be the surgeon's responsibility to adjust ablation software to what he "thinks" will be the best result. Deviation from the refractive target is to be solved once by the software and not by each surgeon. The variety of possible complications is too big in comparison to the amount of patients, to be able to represent a surgeons learning curve on its own. Moreover, complications should not occur, in the light of the fact that Refractive Surgery is selective. The amount of decentration is independent of the refractive error and atmospheric changes and more it includes the contact potential of the surgeon towards its patients. Decentration is even most complicated to retreat. Furthermore, in Tavola's study decentration is the most steadily improving factor in relation to experience. In the opinion of the author, decentration is the best long term indicator of a surgeon's experience. Other indicators are important too, but the absence of complications is a major requirement to start commercial LASIK surgery, and the smallest achievable deviation from target refraction is a major quality indicator anyway.
How to Grasp the Experience
It does not seem very ethical, that about 180 eyes, e.g. 100 patients, are needed, before a surgeon achieves consistently high quality results. Instead, the aim must be that with the first patient operated, the surgeon's experience is already at high level. So far, most surgeon's have been learning LASIK in a patient consuming "do-it-yourself manner". One good reason for this is the fact that LASIK has been at investigation stage, and surgeon's have been trying to find the best procedure. The other reason is a lack of effort to set up an integral teaching program and to play with open cards. People might say that it is still too early, however, the efforts to introduce an integral teaching program in PRK have been very poor. Even in established PRK surgery, most surgeon's learn the procedure in a do-it-yourself manner at the cost of their patients. However, what can be done to ensure that surgeon's are already experienced in LASIK before they have operated on any patients?
Lim suggests that knowledge, skill and experience are needed to perform cataract surgery at best. This must be also true in LASIK surgery. However, what are the differences between knowledge, skill and experience? Here, knowledge will be understood as best, but dead experience, coming alive with skill. Knowledge means to know how to do something best. Skill is the ability of physically applying this process knowledge. Experience can either be obtained in a patient consuming do-it-yourself manner or by taking advantage of the last available process knowledge and accelerating skill techniques. This will reduce the learning curve dramatically. However, many patients will still not be operated on at highest level, therefore surgery must be simulated until the new surgeon has gained sufficient experience. The following picture demonstrates this matter: until the range of quality is not better than the inspection criterion, surgery must be simulated, and the training must continue until the results are within the quality standards. The knowledge used to obtain this goal is the "dead experience" at this point in the learning curve of an experienced surgeon. The area of the arrows demonstrates the effort of knowledge, simulation and skill. Learning the skill is the most difficult and slowest task that must be challenged. Simulation is a matter of resources, and knowledge a matter of constant information management.
Figure 46 is straight forward approach in LASIK teaching, trying to meet the goals set above. It starts off with an awakening experience for the new surgeon. Before the new surgeon is tortured with teaching and listening, he should already have his own idea of what is going to happen. The surgeon is briefly shown what the procedure is about and he will then try LASIK on his own without guidance or criticism. The surgeon should then have his own curiosity and his questions will guide him to the needed focus in the following observations. The scheme of knowledge internalisation will be from the top down, that is to say before going into details, the new surgeon will observe the whole process of surgery. Then he will be the "co-pilot" in the specific fields of surgery. However, even after 30 surgeries he will not have had the possibility to observe all the typical complications of the surgery. Video teaching of these rare complications can than accelerate his experience. The second phase will be finished by an examination requiring all the knowledge needed to perform LASIK. Needed process knowledge should be fully internalised. An oral examination about the general process, and steps to be taken in rare complications, will guarantee best preparation for the following phase. The third phase, skill internalisation by simulation, will transfer the learned knowledge into actual skill. Here, a bottom up approach is preferred: Single microkeratome handling, even with a manual microkeratome to feel the cut, then centration will be trained, at the end the complete process of surgery will be simulated. It must be mentioned, that centration teaching is adjusted according to the talent of the surgeon. However, if the new surgeon does not show improvement in centration and does not reach the required standards, further teaching should be stopped.
The surgeon should now be prepared to guarantee sufficient precision and even owe "accelerated" experience to handle complications. In phase four the new surgeon will start real operations. However, to minimise risk, his first patients should be amblyopes and of a myopic nature. After the new surgeon has operated his first 40 eyes in assistance, he may obtain his "LASIK driving licence" to fully perform his own surgeries. However, he may not start hyperopic ablations until after his last 20 surgeries have been fully centred. All his surgeries should be fully controlled statistically, and aggregated information should be sent to refractive authorities. Moreover, this data will serve for the continuous improvement process. Each surgery should also be recorded and archived for a certain time, allowing round table discussions to maintain continual improvement.A Guide to TQM in LASIK
The flow-chart (fig.48) outlines a best practise pattern to the decision making path in LASIK surgery and summarises the thesis for the interested ophthalmologist. The numbers cited in the flow-chart refer to information discussed in the previous chapters.
Refractive surgeries seem to be a rather quickly learned compared to other surgeries in ophthalmology. However, due to the fact that it must compete with harmless prosthetic "competition" highest standards are essential. Where as in usual "non-elective" surgery fair results still may justify the operation, Refractive Surgery must never decrease best corrected visual outcome after surgery. Besides best surgery, a perfect presurgical selection is of upper importance to obtain that all patients who have undergone surgery do not regret their decision.
A Total Quality System for LASIK has been built in the last chapter. After true patient oriented quality characteristics had been discussed, the patients "individual input" was analysed. Then realistic quality indicators were defined. Knowing the goals, the processes and potential quality of the clinic were analysed and newly designed. The flow-chart (fig.48) outlines a best practise pattern to qualify highest standard LASIK surgery.
Of course, there are many ways of how and at what stage decisions should be taken. However, a preferred practise pattern will be essential for Total Quality Management. Moreover, it gives ophthalmologists a quick overview about LASIK surgery and it is a good orientation to start a structured discussion on LASIK procedures.
A best practise pattern in any medical procedure should fulfil various requirements. The goals which a best practise pattern in LASIK surgery has to fulfil are listed below in accordance to their priorities. Specific goals to be especially mentioned are written below their general goal.
The process of presurgical selection has been designed to fulfil these goals. The decision making has been developed into three major steps (fig.48). In the first two steps the patient is checked to ensure the absence of any clinical contra-indications, thereby most obvious contra-indications come first. This advance ensures that presurgical selection is cost efficient and kind to the patient.
Even at the early stage of appointment making some contra-indications can already been checked. However, here the information must be obtained in a very informal way and the patient must never be frightened by mentioning specific contra-indications. Only in the case the patient does not fulfil the requirements, the contra-indication should be mentioned and explained. For instance, asking the patient on the phone, whether he depends on only one eye, will certainly not improve the integration of the patient. Instead all relevant information can be obtained by asking for the reason for his last ophthalmologic consultation. Even telling all patients that they must be above 18 years can generated undesired questions. Only if the patient's voice suggests an age below 18 years, the question might be asked. At this early stage it does not really matter, if obvious contra-indications have not been checked completely, if otherwise the patient might be lost. In this very early phase it is most important to motivate the patient to be willing to undergo the complete selection phase.
During the first part of his first consultation nearly all possible contra-indications will be checked against the facts and the first set of necessary data for surgery is obtained. During the second part of the consultation, complete measurements for the LASIK surgery are being taken. Last information about the existence of very seldom contra-indications is also obtained. The big corneal measurement exists of traditional keratography, modern topography and cycloplegic vision examination. Although the traditional keratography is not essential, it helps to improve to find the individual visual center at surgery. Moreover, it verifies and identifies the processed data of modern topography. Pictures of modern topography can easily be exchanged, where as pictures of traditional topography still show the complete eye of the patient. After the cycloplegic vision examination the retina needs to be fully checked to ensure that there is no sign for retinal surgery during the first three months after LASIK surgery, as this surgery requires a healed/clear cornea. This examination is particularly important in high myopic patients who have a much higher possibility to suffer from a sudden tear of retina. The sequence of the described examinations should not be changed as only few sequences allow to take all necessary examinations on the same day.
After all possible contra-indications have been checked against the facts and complete clinical data has been obtained the question whether the potential quality of the patient allows full ablation can be answered. If the questions turns out to be positive the patient should be asked for scheduling the surgery. If the potential quality of the patient is limited he should then be asked about his subjective priorities of vision in the fields where his vision might be limited after full laser correction. Then the surgical parameters can be matched with his personal priorities. However, only if the scheduled outcome can fully meet the individual expectation surgery is to be scheduled.
During the first year after the surgery the patient should undergo four controls to ensure the success of surgery and improve the quality standards of the institution. The complete process of Refractive Surgery should be controlled by computer-assisted information management. Statistical process control is essential to point out any imperfections as early as possible and to reach or even improve quality goals. For some patients training of vision will ensure successful adaptation of their improved but changed vision.