Lasik Eye Surgery: The success of laser vision correction or LASIK depends on a multitude of factors, primary being the expertise of the doctor along with a good laser technology in an International standard set up of hygiene and care with stringent eligibility criteria. Dr. Anand Shroff, Chief Surgeon, Perfect Wave LASIK Centre at Mumbai, has several years of experience in LASIK and is among the country's longest-standing users of the benchmark 'flying-spot' laser technology. He also is the first to use the WaveLight Allegretto 200 Hz excimer laser in India before the most recent Allegretto Wave Eye-Q 400 Hz was launched at our Eye Hospital.  

Wavefront LASIK or custom LASIK is the most advanced LASIK method today. It can be performed using various lasers. The speed of the laser and its applications are very important in delivering results. Today, we use the worlds fastest laser the 400 HZ whereas most other lasers are close to 50-100 Hz and some to 200-250 Hz.

Wavefront technology has been around since 1998. It is specifically for those patients who would end up unhappy if a standard LASIK procedure is done on them. These patients are detected during their LASIK screening and evaluation, by certain specific indications which would arise on the topography and aberrometry tests

We believe in the best, having always stood for distinction in eye care. After working on different lasers and being offered other lasers like Mel 80, Zyoptix, VISIX etc. some, still entering the market, we went ahead with the Wavelight wavefront 400 Hz laser because of its superior technology. Most lasers are retrofitted for wavefront or to simply put upgraded whilst this laser has been developed for wavefront from scratch. The detailed research in the laser system took into account the needs of the surgeon, patient as well as looked after the many drawbacks of the other laser systems. 

To put it simply, the 'wavefront' is the way the natural light pathway goes in the eye thru the entire optics. This is supposed to be a smooth path in an ideal eye. As the light travels thru the other optical system inside the eye, like the lens, vitreous jelly etc. it undergoes further degradation. This is acceptable to a certain extent and that is why the eye surgeons have reached a 6/6 criteria as normal sight. However, when these errors or 'higher order aberrations' as they are known, exist to an extent in which they need to be treated then wavefront treatments are a must for such patients.

Earlier lasers without wavefront technology can only correct the spectacle number, which arises from the curvature irregularities of the cornea. Our laser can treat the entire optical system errors. Further, when we treat these optical errors by doing wavefront, some patients actually gain lines of sight, better than 6/6.

EVALUATION OF A CANDIDATE FOR LASIK EYE SURGERY

We evaluate pupil size, dryness of eyes, corneal thickness, topographies etc in our LASIK evaluation. The thickness of the cornea is a very important aspect of screening. We do this with a digital pachymetry test, which would determine if your eye is suitable for LASIK.
 
What we need from you [the patient] is

1. No contact lens wear for 5 days to a week [soft CL] before coming to our centre for evaluation. This is because the lenses sit straight on top of the cornea and flatten it. We need accurate measurements and we want to perform this procedure just once.

2. The procedure of evaluation takes an hour and a half in our office since we dilate the pupils.

3. After the evaluation, if the patient is found suitable enough for the Lasik procedure then the LASIK procedure takes just about 20 mins in all and normally both eyes are done in one sitting. The laser treatment itself is very short. Our laser treats one dioptre in 2.5 secs, so the actual treatment even for numbers like minus 12 takes just 30 secs. This is the 400 Hz difference you get.

4. We send you home immediately after that explaining the after care of eye drops, see you next morning once and at least 3 days later.

We give detailed report with which follow ups can be done in your city. These follow up examinations need not be done before the 3rd month, and that too with an optometrist, not necessarily an eye surgeon. So there you have the flexibility as we have done our professional work and after care instructions are given to the patient.

As far as your refractive error is concerned, the results are very predictable and stable provided we find your eye fit to undergo the procedure.

Hence, if this visit is specifically for LASIK, then we request certain tests which would determine your fitness such as the pachymetry [test for corneal thickness] if you have numbers higher than -3.00 D. Another test is the topography, which gives maps of the eye and screens out abnormal cornea. This is only done so that the trip is successful.

It is most important that you choose the centre by seeing a combination of factors. The expertise of the doctor, the international standards that they use and hygiene of the centre and also important the laser machine. Many doctors today budget the LASIK and discount LASIK prices esp. in India. This is only possible if one can cut costs, but that would be at the cost of compromising quality, re using blades, working with older cheaper technology etc. Many use the Nidek and Mel 70 lasers which give problems in night vision and glares in over 50% of their patients. These lasers do not have wavefront technology either. In the USA the FDA has even proven that most complications arise in discount LASIK centers world wide, let us face it and be honest in what is in offer!

There is a lot more of this laser, which helps the patient and the doctor. We can now treat higher numbers with more accuracy, re- treat earlier laser unhappy patients to get better night vision etc. and include patients who would have been poor candidates for earlier technology. This is why our success rates have been good from the beginning, as we have been thorough in our patient evaluation and stringent in our eligibility criteria. We have simple health care philosophy, complete education to a would be patient with details on doctors, centers  as well as latest in technologies that is why sometimes our detailed mails are called upon as too verbose ! But we like to be informative that is where we pride being the only medical trip packaging company in India which specializes in core competence knowledge bases and sharing of complete medical procedures with a would be patient and for us mere monetary satisfaction is secondary, a patient's safety as well as health and handling of a patient is the primary focus.

The difference between wavefront or custom and non wavefront LASIK in a simple way explained;

The way I explain to my patients here is whenever you see an ophthalmologist for an eye examination and he is doing the refraction, he depends on your answers whether the letters on the chart shown to you is clear or not. The refraction that you are comfortable with is what is your best-corrected vision, which again is subjective, because you do not know if you can see clearer than that or not. Secondly, this refraction jumps in 0.25 digits. i.e.. if your numbers read 3.25 this visit, the next visit it may read 3.50 or 2.75. The refraction, which you read the line of 6/6 well, is what is fed into the laser. A laser will treat anybody's 3.25 the same way as it would treat yours in standard treatments!

With wavefront technology, we go beyond clinical refraction with our wavefront analysis. The numbers that we get are in 0.01 accuracy. ie, with this machine your numbers would read 3.27 or 3.28 [examples]. We take 5 maps of each eye and hence have very accurate readings. Furthermore, the readings are customized with each eye.

With this, it eliminates internal optical errors and one can have the opportunity of seeing better than they have with glasses or contacts.

Another advantage is dynamic refraction. Simply put, in the night when the pupil expands, due to certain changes, there are some people who have a change in refraction in the night. ie. their numbers read differently for the day and for night. Standard LASIK treatments cannot address this issue. Hence amongst all lasers be it even other wavefront lasers, the Wavelight Alegretto Eye Q 400 Hz laser helps us tremendously as we have near zero night vision problems as it follows the dynamic refraction principle. This is not present in most lasers.

There is the Bausch and Lomb laser 'Zyoptix' which you may have come across, which is also doing wavefront treatments but as a basic laser from the 217-technolass [its non wavefront laser], it has not changed much. the Wavelight laser on the other hand was built from scratch to suit wavefront treatments.

The Wavelight company [our laser company] was the first laser to have done the worldwide wavefront LASIK treatment which others have modified or upgraded in their already existing lasers.

There are many other differences between the two lasers. If you still want to learn more, run through the matter below, although I must tell you that it is a bit technical and lengthy even though I have tried my best to simplify it!

The 217 B & L is the earlier gen laser, their newer laser being the Zyoptix.  217 has a speed of 50 Hz which the Zyoptix has improved to 100 Hz. We work at a speed of 400 Hz with this wavelight machine. I have compared their new laser [Zyoptix] with our machine, as it makes no sense to compare a non wavefront to a wavefront laser.
 
Some other glaring differences are that the B & L wavefront laser [Zyoptix] comes with a microkeratome [that makes a flap on your cornea] called the Hansatome that makes a very thick flap. A thinner flap means a stronger cornea after the laser, hence thin flaps are better when possible. We use the Moria and have the SU [single use]. Also,the Allegretto Wave tracks your eye and treats much faster than the B & L [Zyoptix] which basically hasn't changed much as a laser in 7 years. In short, the Allegretto Laser which we use has better technology than the B & L [Zyoptix] Z100 in our experience.

1.The Zyoptix takes off much more cornea than the Wavelight laser which we use.
2. The Zyoptix comes with a Hansatome which makes a thick flap and uses more of the corneal tissue, leaving behind a very thin stromal bed
3. During the Zyoptix treatment the laser will stop many times since it treats in phases with several pauses during the actual laser firing time. This is not so with the Wavelight, which treats the numbers off in one go as it has a plume removal system.
4. The Wavelight comes with an attached Slit-Lamp which ensures an absolutely clean interface.
5.The Zyoptix machine comes with open optics which has more exposure to dust etc.
6. The US FDA gives a safety limit of 250 microns to be left behind after treatment.

Though the information is exhaustive, I find it imperative for you to understand the technology before choosing your LASIK centre. Below is a comparison of our laser with others.

FEATURES OF OUR LASER COMPARING WITH OTHER LASERS

1. Laser Spot Size
The small laser spot size is mandatory to produce fine complex treatment patterns. Smaller the size, finer the treatment. Ours is the smallest in the world so far. viz 0.68 HM

2. Speed
Shortens ablation/ treatment time remarkably. To the benefit of the surgeon and to the comfort of the patient, Because shortened corneal exposure time allows faster visual recovery. The rapid rate is vital to maintain corneal hydration intra-operatively, especially in wavefront guided procedures with larger optical zones where a prolonged treatment time could adversely affect the planned treatment profile. A simple principle in laser refractive surgery is to keep the eye as physiologically hydrated as possible intra-operatively for a faster visual recovery.  Hence, faster speed lasers have better visual outcomes. Our is the fastest in the world so far. viz 400 Hz keeping in mind the safety limit as well.

3. Optical Zone
Ideally the laser should have the widest treatment area that also removes the least tissue possible, which is what our laser supports. Most Other lasers in order to treat a wider area, take out more corneal tissue. This also results in night vision problems. In the night the pupil expands or dilates to let in more light for visibility. If a laser treats a zone, which is smaller in diameter than the diameter of expansion of the pupil, then what you have is an untreated rim of cornea, which in the night is going to result in haloes or glares of light. Most lasers treat upto a 5 mm zone to 6 mm only , ours can treat upto 7 mm.
In cases of patients with night glare due to earlier treatments, the ability of our laser to retreat is highly beneficial.

4. Eye Tracking speed
The eye is kept fixed with the laser during treatment. However there are fine saccadic eye movements not seen by naked eye. The Wavelight Allegretto 400 Hz is better than any other excimer laser system as it tracks the eye at 400 times a second and allows for spot on treatments. Most other lasers have an eye tracker which if the eye moves even to some extent during treatment, then the laser stops.

5. Topography Link treatment
Is necessary for a customized laser treatment. Especially in re treatments when undergone earlier LASIK and patient is unhappy. For topography-linked retreatments, the Wavelight Allegretto laser has the best capabilities at present.

The Allegretto is better technology than the B & L Z100 in our experience.
 

We are proud to say that within an ISO 9001:2000 certification hospital (and soon to receive JCI Accreditation) combined with strict patient care protocols and with a Wavelight laser that has been launched world wide only in Jan 2004, being one of only few centers in the world and the first hospital in India to have the 400 Hz wavefront technology, we offer a far superior, safe and reliable technology at affordable comparable prices.