The eye and vision errors
The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects.  Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects.  Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery. In LASIK surgery, precise and controlled removal of corneal tissue by a special laser reshapes the cornea changing its focusing power.

REASONS TO UNDERGO LASIK

Some of the common reasons why people undergo LASIK or get rid of their spectacles and contact lenses are : contact lens intolerance, cosmetic reasons, social (marriage), tired of wearing glasses, and lifestyle activities that are inhibited due to glasses or lens wear such as outdoor sports like golf, football, water sports or hiking. In some careers such as Merchant Navy and Airways it is a requirement to have 20/20 or 6/6 vision. LASIK helps tremendously here.

Spectacles are cosmetically unappealing for some. There is a degree of distortion when looking through the periphery of the glasses, the field of vision is reduced and on leaving a cold room moisture can fog the glasses and blur vision for a few minutes. Hence glasses are unacceptable for certain careers. Contact lenses require motivation with great attention to hygiene during insertion and removal, failing which sight - threatening infections may result.

LASIK overcomes all these disadvantages.

Light falling on the cornea [the front surface of the eye] has a smooth curvature- referred to as a "wavefront". As this smooth wavefront shape courses through the various optics of the eye, ocular aberrations [imperfections] are induced. It results in an irregular wavefront curvature reaching the retinal surface, which degrades the retinal image quality. An aberration-free eye would result in a smooth wavefront image on the retinal surface. Wavefront-guided customized LASIK, also referred to as "customized ablation" or custom LASIK performs corrections based on individual wavefront measurements.
Current refractive procedures such as traditional or standard LASIK correct lower order aberrations such as spherical and cylindrical numbers alone. However, higher order aberrations affect the quality of vision and may not significantly affect the vision as read on the chart. It is these subtle deviations from the ideal optical system, which can be corrected by wavefront procedures, and thereby improve image quality.

 

A personal consulatation with the LASIK specialist Eye Doctor is organized.
A complete eye assessment is then carried out to check a patient's suitability for LASIK.

Tests include refraction, contrast sensitivity, pupil size, pupil reaction, slit lamp examination, retinal examination, tonometry, pachymetry, aberrometry, topolyzer measurements, topography and tests for dry eye amongst others. These tests would take about 60-90 minutes as it includes pupillary dilation.

A customized treatment plan is developed and pre-procedure instructions explained to you.

 

This is an outpatient procedure that usually takes 5-10 minutes per eye. The actual laser treatment usually takes a few seconds. First you will lie on the motorized bed. The eyes are anesthetized with eye drops only. The head is positioned under the laser. A soft clip keeps the eyelids gently and comfortably open during the treatment. You will be asked to look at a soothing green blinking light during the entire procedure.

During the treatment, an instrument called the microkeratome creates a corneal flap to make it a painless procedure. The computerized Excimer laser uses a beam of light to gently reshape the cornea so as to alter its curvature to the desired extent. The flap when replaced on the new corneal curvature allows images to be sharply focused on the retina. The goal is to eliminate or greatly reduce the dependence on glasses or contact lenses.

Once the procedure is completed, a soft contact lens or shield is sometimes placed on the eye. A post - procedure eye examination is performed and eye drops are prescribed. There may be mild discomfort for a few hours after the procedure.

 

If you are a contact lens user, please ensure that you have stopped using your soft contact lenses a week before, or semi-soft [rigid] contact lenses at least 3 weeks before the procedure date.

Do refrain from wearing any form of eye make-up for 2 days before the procedure. If possible thoroughly clean the eyelids and lashes of remnants of eye make-up.

Avoid wearing scented lotions, perfume, cologne, hair spray, mousse or gel on the procedure day as these may adversely affect the outcome of the procedure.

You may take a hair bath the day of the procedure, as washing of hair is not permitted for 48 hours post-procedure.

Please have a light breakfast on the day of the procedure. You will need to have somebody accompany you to understand the post-procedure instructions and escort you home. You will not be able to drive home after the procedure.

You can expect to be at the clinic for approximately 2 hours for your laser vision correction procedure.

It is crucial to the healing of your eyes and your visual recovery that you follow all of these instructions exactly as directed:

DO NOT rub or touch your eyes and DO NOT squeeze your eyes.

Follow the eye drop doses and put in your eye drops exactly as instructed. Please wash your hands prior to instilling your eye drops, preferably by someone else. Shake the eye drop bottle before use. Artificial tears may be used as often as required.

Try to rest the whole day. For 6 to 8 hours after the procedure expect irritation, redness, tears, light sensitivity and slight swelling. For the most part of the day your vision will be hazy.

It is important that you protect your eye for the day. In order to prevent inadvertent rubbing of the eye, be sure to wear eye goggles while sleeping or napping.

The next morning the functional vision is usually restored. However as the healing is happening in the line of sight, there may be some days when the vision is slightly fuzzy and other days when it is very clear. This fluctuation typically lasts about 7 to 10 days.

Wear sunglasses while outdoors for a few weeks. Should you experience severe discomfort, pain, discharge or sudden haziness of vision, call your doctor immediately.

Please do not try to do the following until instructed to do so by your doctor: showering, bathing, exercising, tanning, reading, computer use, driving and applying eye make-up.

Avoid "knuckling" the eyes and swimming for a month.

Your post-procedure appointment schedule: You will be seen the next day and if in Mumbai, after one week. Visits upto three months are included in your LASIK package. If you have any questions, you are free to call the hospital and make an appointment.

Detailed written instructions, eye drops and protective eyewear required for the immediate post-procedure period will be provided by us.

 

An improvement in vision is noticed within 4-6 hours with restoration of functional vision by the next morning. However, complete recovery may take upto 48 hours. Some people get back to work the day after treatment. Two or three days are suggested. For a few days after LASIK, patients may experience blurriness of vision. This is part of the healing process and this blurriness usually clears up in a few days.

LASIK is a permanent treatment. However, patients who are 40 years and above, may require reading glasses. During your consultation we will give you can an idea of the procedure and the level of vision you can expect. Millions of patients worldwide and thousands with our doctor have had an Excimer laser refractive procedure done on them successfully.

 

Before

After

 

 

 

 

 

An instrument called the Aberrometer maps the errors in the optical system of the eye [wavefront analysis], which is linked to the laser before treatment. The wavefront analysis is customized for the individual and hence offers the most ideal treatment available for the patient from all currently known vision correction procedures.

A square grid of 128 thin parallel and equidistant rays is projected into the eye.
The pattern of distortion of the regular grid determines the optical errors of the eye. In an aberration-free eye the grid pattern projected on the retina would remain unchanged and deviations of each spot when present are measured by means of a computer.
The Aberrometer captures five consecutive wavefront analysis measurements through a dilated pupil to map all the aberrations.
These maps are then used to generate a composite wavefront profile, which in turn guides the laser treatment profile and spot pattern.

Wavefront analysis-guided LASIK now makes it possible to treat a larger spectrum of patients. The WaveLight 500 Hz Concerto Laser offers individuals who are not entirely satisfied with their outcome of earlier treatments such as radial keratotomy [RK], PRK or even LASIK on first generation excimer lasers, the benefit of a topography-linked procedure [mapping the irregular corneal surface and making it regular]. This procedure gives the best possible uncompromised vision.

 

Our WaveLight 500 Hz Concerto Laser, especially because of its unique corneal tissue saving feature, enables us to re-treat corneas, which would have been otherwise too thin to work upon.
Some people who have already had LASIK with earlier technologies and experience night vision disturbances can be helped with our customized topography-guided treatments.
Wavefront measurements of LASIK patients with such quality of vision complaints may demonstrate a high magnitude of higher-order aberrations.
Studies demonstrate that topography or wavefront LASIK retreatments can reduce these aberrations as well as subjectively improve these night vision and contrast sensitivity problems. Each patient needs to be individually assessed to make proper suggestions.

Post-op Refractive Surgery Complication Management: Refractive surgery complications can be divided into those which are surgically induced and managed and those which are healing or ablation related and typically require further laser retreatment.
Examples of surgical complications would be:

Examples of healing and ablation related complications are:

There is of course considerable cross-over as many surgically induced complications produce loss of contrast sensitivity, loss of best corrected vision and severe disturbances in night vision. While we have been managing surgical complications for several years, the development of wavefront technology has allowed us to finally fully evaluate all these patients and present possible treatment options for them. In about 70% of cases, we are now able to provide topographically guided solutions for patients. It is impossible however to predict which patients will be the most suitable candidates with the best chance of success until completing the diagnostic wavefront and topographical testing. The WaveLight 500 Hz Concerto Laser has been our excimer laser system of choice as the Tscherning wavefront analysis system has provided us with reproducible detailed data in the majority of cases for surgical planning. The laser system also possesses specific features ideal for both the new patient and the post-refractive surgery patient for higher quality visual results:

The small laser spot size is mandatory to produce fine complex treatment patterns. The rapid repetition 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 with less risk of swelling and epithelial ingrowth. In cases of patients with night glare, the ability to create a prolate 7 mm true effective optical zone with a 9mm blend zone is highly beneficial. Lastly, the eye-tracking response time must be short enough to adequately account for saccadic eye movement. The Wavelight Allegretto response time is better than any other excimer laser system without the need to dilate the pupil, which allows the patient to fixate on the target light more easily with a faster visual recovery.
For topography-linked retreatments, the WaveLight 500 Hz Concerto Laser has the best capabilities at present. It should be understood however that the diagnostic analysis is what determines the final treatment method of choice recommended to any individual patient.

The WaveLight 500 Hz Concerto Laser is a laser that provides the doctor and the patient the highest level of safety, accuracy and reliability in LASIK, allowing the doctor to truly customize and offer a treatment that is ideally adjusted to the individual needs of the patient.

The WaveLight 500 Hz Concerto Laser saves upto 40% of valuable corneal tissue for every dioptre of treatment when compared with other lasers. This results in the doctor being able to treat a higher power range keeping in mind long-term safety as well as treating lower powers with unmatched stability.

Superior performance as compared to other lasers used in India today and comparable to the best available worldwide.

The laser we use is the 400 Hz, more advanced than the one compared by US FDA, thus providing you with the highest level of safety, accuracy and reliability worldwide in LASIK.

The graph shows that as refractive errors [spectacle errors] climb higher, the performance of most lasers falls. The Wavelight laser can treat higher numbers with far more accuracy and predictability. You can also check what the USA FDA says about various laser performances on
http://www.fda.gov/cdrh/LASIK/lasers.htm