About Lasik Surgery


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A Practical Guide to Laser Vision Correction Procedures

Dr. Chynn and his team of laser vision correction professionals at Park Avenue Laser make it an ongoing mission to provide their clients with clear and practical information about Lasik and the many variations of procedures available for the treatment of vision problems. Patients come to Dr. Chynn with a range of vision difficulties that usually require corrective glasses or contact lens, such as:

Myopia: Also known as “nearsightedness”, this condition refers to the ability to focus clearly on objects close at hand, but not those at a distance.

Hyperopia: Also known as “farsightedness”, problem is just the opposite of myopia in that images are seen clearly far away, but the eye cannot focus on objects that are very close by.

Astigmatism: This common condition is caused by a deformation in the curvature of the cornea causing incorrect focus of light rays and distorted vision.

Presbyopia: Often confused with hyperopia, this term refers to a normal change in the eye in which people, usually beginning in the 40’s, have increasing difficulty reading as they get older due to a change in the crystalline lens which prevents good focus for near vision.

Each type of vision problem requires a different laser vision correction technique and each client comes with their own unique set of eyes. Dr. Chynn’s approach is highly individualized for every patient and treatment is based upon the presenting problem, the degree of vision impairment, the structure & function of client’s eyes, and the treatment goals of the individual. As part of Park Avenue Laser’s quest to thoroughly educate their clients in the variety of laser vision correction strategies available, the following technique descriptions have been prepared as a practical reference for those considering Lasik, Lasek, Epi-Lasik, or other laser vision correction surgeries.

Varieties of Laser Vision Correction Procedures

Several predecessors of the laser vision correction strategies detailed below have come and gone over the last several years. These are the most common laser eye surgeries for vision correction in practice today.

PRK:

PRK (photorefractive keratectomy) used to be the most common refractive eye surgery before the advent of the Lasik procedure. The procedure is somewhat more uncomfortable overall than Lasik and other newer techniques and healing to optimal vision levels takes longer in comparison. Most PRK patients can expect 10/20 results (about 70%) and the vast majority achieve at least 20/40 vision (90-95%), which is legal for driving in most states. PRK is still the laser vision correction treatment of choice for many eye surgeons for patients with larger pupils and thin corneas. PRK can effectively improve myopia, hyperopia, and astigmatism.

First invented in the early 1980’s, PRK received FDA approval in 1995 after seeing many years of successful practice in other countries. PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to ablate tiny bits of corneal surface tissue. This reshapes the cornea in order to focus light more correctly onto the retina and improve the clarity of vision. A map of the unique cornea of each eye is made before the procedure, the eye is anesthetized and stabilized, and the laser vision correction prescription is set via computer. The eye surgeon then uses the excimer laser, while the eye is under constant surveillance via microscope, to remove tiny bits of the cornea with pulses of light. The client is awake during this procedure and then relaxes for a short while at the doctor’s office before being driven home by a family member or friend.

Standard Lasik:

Dr. Emil Chynn was the very first eye surgeon in New York City to offer the Lasik procedure and after many thousands of cases, is the only high-volume Lasik surgeon in NYC with a perfect track record.

Before the Lasik procedure begins the eye is anesthetized to prevent both pain and movement. It is then immobilized with a suction ring for further security. The surgeon uses a microkeratome blade Dr. Chynn uses the proven and popular Bausch & Lomb Hansome microkeratome) or a laser to cut a flap from the top 20% of the corneal tissue and then lifts it aside. The excimer laser (Park Avenue Laser owns the highly reliable VISX Star S4 with ActivTrak) is then calibrated and the surgeon then sculpts the cornea to the correct prescription.

The procedure is always short but actual time depends on the degree of visual impairment needing correction. The corneal flap is replaced, which adheres without suturing to the cornea. Recovery is much like that described in PRK with 20/20 vision often reached in just a couple of days and rarely in more than a few weeks. The Lasik method using a second laser for the flap creation is known also as Intralase Lasik and has its own set of pros and cons when compared to the microkeratome technique.

For more detail on the Lasik procedure, read Dr. Chynn’s excellent explanation at our page about Lasik Surgery

Wavefront-Guided Custom Lasik:

Wavefront Lasik, also known as Custom Lasik, is highly individualized laser vision correction using 3-dimensional mapping measurements of how the eye processes images to computer-guide the laser in the proper sculpting of the cornea. The wavefront mapping and corresponding vision correction is extremely precise and personalized. The technique is groundbreaking in that it has the potential to not only improve how much a person sees, but also the quality of vision in terms of improvement in contrast sensitivity and fine detail. Risk of post-Lasik complications, such as glare, halos, and poor night vision, are significantly reduced, and if these conditions are pre-existing they can often be treated with Wavefront Lasik procedures.

The majority (76% as of 2005) of eye surgeons use Wavefront laser vision correction technology in their practice now. This method produces improved results, over conventional Lasik, in visual acuity greater than 20/20, improvement in higher-order aberrations, and a decrease in post-op complications. The Wavefront technology is now being combined with even newer laser vision correction techniques with great success.

Dr. Chynn was the first laser eye surgeon in NYC to routinely blend the Wavefront technique with no-flap procedures such as Lasek and Epi-Lasik.

Lasek:

The Lasek (laser epithelial keratomileusis) laser vision correction procedure is a newer technique mostly used for people with corneas to thin or too flat to do well with traditional Lasik. Lasek was developed to lessen the occurrence of complications related to the flap created during the traditional Lasik surgery.

With Lasek eye surgery the very outer layer of the cornea, is cut not with the microkeratome blade used in LASIK, but with a finer blade called a trephine. The surgeon then washes the eye in an alcohol solution for about 30 seconds which loosens the edges of the corneal tissue layer. After sponging out excess solution, the surgeons utilizes a very small hoe to lift the edge of the created flay and fold it out of the way. The excimer laser is then used by the surgeons to sculpt the cornea to its correct prescription. A spatula blade places the corneal tissue back in place and healing occurs much like that described in Lasik or PRK. The patient typically wears a bandage contact for four days and it takes about seven days to reach full visual correction.

Epi-Lasik:

Epi-Lasik is one of the “flapless” laser vision correction procedures that have become extremely popular recently due to low chance of complications and excellent results with very little pain for the patient.

Like the Lasek procedure, Epi-Lasik involves cutting the cornea's outer layer, the epithelium, in a thin sheet that retains its hinge on the eye, but for the Epi-Lasik technique the eye surgeon uses a plastic oscillating spatula blade to loosen the sheet of corneal tissue, and without the alcohol solution used in Lasek that can cause a serious reaction in the eye. An excimer laser is then used, as in standard Lasik or PRK, to sculpt the underlying corneal tissue. The epithelial tissue is then replaced with the spatula and a special contact lens with high oxygen permeability to allow for protection and healing. Patients often achieve 20/20 vision in three days, but optimal vision can sometimes take several weeks.

According to Dr. Chynn, patients who practice meticulous eye care post-laser surgery tend to have the best and quickest results.

The Epi-Lasik procedure is often the laser vision correction technique of preference for patients with very thin corneas or for individuals who participate in high-contact sports or professions (such as boxers, policemen, tennis players) who have a higher risk of having the Lasik flap dislodged.

Dr. Chynn and the team at Park Avenue Laser in provide individualized treatment choices to their valued clients. Each patient’s eyes and needs are unique and individuals are treated so at this Manhattan eye clinic. Other eye procedures, such as Monovision Lasik, are also available through this practice and are discussed in other portions of this website. Please contact Dr. Chynn and his experienced staff with any questions about laser vision correction or to schedule a free comprehensive consultation.