SURGICAL VISION CORRECTION AND LASER VISION CORRECTION

The Procedures And The Risks

Eyeglasses And Contacts

Surgical and Laser Vision Correction is available for most people who need corrective lenses to see 20/20 when looking at distance. The traditional method for correcting vision at distance is eyeglasses. In the 1940's [Contact Lenses] were invented. The advent of the [Contact Lens] created another option to standard [eyeglasses]. The [Cornea] or front surface of the eye is responsible for most of the refractive power in the eye. [Contact Lenses] when placed on the [Cornea] create an artificial curve altering the effective power of the eye. Surgery to alter the power of the [Cornea] was to follow two decades later.

ALK - Lamellar Keratoplasty

The first surgery used to alter corneal power is known as [Lamellar Keratoplasty] or [ALK]. Developed in South America, part of the Cornea is removed, frozen, lathe-shaped and reinserted. The results are acceptable and the procedure is still performed today, but alternative procedures exist that are safer and more precise.

RK - Radial Keratotomy

In the 1970's surgery was developed to correct [nearsightedness]. The idea was to alter the curve of the Cornea by placing incisions that scar and flatten the [Cornea] thus changing its power. The surgery is called [Radial Keratotomy] or [(RK)]. During [RK], a surgeon makes several incisions around the periphery of the cornea with a diamond tip scalpel. The incisions are usually 90% the depth of the [Cornea], scarring it all the way through. As the wound scars, the [Cornea] is flattened, reducing the nearsighted prescription.

The surgery can provide very good visual results, but has certain problems. Incising the Cornea weakens the structural integrity of the [eyeball]. As time passes, many people suffer a gradual shift from good vision soon after the surgery to farsightedness over time. [Farsightedness] can cause distance blur and almost always makes reading very difficult if not impossible without corrective lenses. I have seen several patients 7 years out after receiving [RK] who had shifted from a prescription of -5.00 Diopters (nearsighted) to +3.00 to +5.00 Diopters (farsightedness).

The Procedures And The Risks

Before discussing [Laser Vision correction], it is important to note that although these procedures are successful more than 98% of the time, they are considered eye-surgery. Blindness is a real and potential risk of any eye surgery and, while problems are rare, they can occur. Proper follow up and monitoring by your [eye care professional] is tantamount to successful treatment of any refractive condition

PRK - Photorefractive Keratectomy

In 1987, the [Excimer Laser] was used on the first seeing human eye to correct [nearsightedness]. The [Excimer laser] is also used to etch microchips. The laser can create etchings 1/1000th the thickness of a human hair. The initial laser refractive surgery to gain approval of the F.D.A. was [Photorefractive Keratectomy (PRK)]. The patient undergoing PRK receives an eyedrop to numb the cornea. The surgeon uses a device that helps to hold the lids apart. The surgeon then uses a surgical tool to gently erode the thin surface layer, or [Epithelium] of the Cornea, exposing the layer beneath, the [Stroma].

The patient is asked to stare at a small red light directly above them. Prior to the surgery, calculations for the patient's prescription are entered into the laser and the amount of laser pulses necessary to correct the vision are calculated. The surgeon controls the laser pulses with a foot pedal. Should the patient inadvertently look away, the surgeon can take his foot off the pedal before any harm is done. [PRK], unlike [RK] does not damage the structural integrity of the eyeball. It does damage a layer of the [Cornea] known as [Bowman's Membrane].

This will be discussed in the next section. Eyes that have undergone [PRK] are just as strong after surgery as before. The procedure only affects the to 10% of the cornea, where [RK] affected 90% of the depth of the cornea. The first person to undergo [PRK] in 1987 is still 20/20 today. Eyes that have undergone [PRK] will be painful and sensitive to light for several days. Several visits to the doctor for [post-operative care] are necessary within the first week of treatment. Vision usually can take 2 weeks to 3 months to become clear. [Glare] can be a problem for up to 6 months after the surgery.

Now: The Procedures And The Risks

LASIK - Laser Assisted In-Situ Keratomilleusis

[Laser Assisted In-Situ Keratomilleusis] or [(LASIK)] is now the laser surgery of choice for most people seeking [laser vision correction]. [LASIK] is similar to [PRK], except it involves considerably more surgical skill and one incision. The incision is very different from an [RK] incision. The surgeon makes the incision with an extremely precise instrument known as a [microkeratome]. The [microkeratome] is similar to a lathe and creates a flap on the surface of the cornea. The flap is no more than 10% the depth of the cornea. The flap is raised and layed aside by the surgeon and the laser performed on the exposed interior of the [Cornea], or [Stroma. The laser is programmed for the patient's prescription in a similar manner to [PRK]. [LASIK] can be thought of as [PRK] under the surface of the [Cornea].

When the correct amount of laser pulses have been delivered to the exposed [Stroma], the flap of [Cornea] is gently replaced and seals itself through capillary action . [LASIK] does not destroy a thin layer of the[ Cornea] that exists below the surface layer, called [Bowmans Membrane]. [PRK] destroys this layer. Doctors and Scientists argue about the function of the layer. It doesn't seem to have much physiological importance short term. It is my opinion and that of others that maintenance of [Bowmans Layer] may play a role in the health of the [Corneal Epithelium] years down the road. In any event, [LASIK] is arguably a better procedure than [PRK] in terms of healing time, comfort, visual result and maintenance of [Bowman's Layer]. [LASIK] eyes are comfortable within 24 hours of the procedure, with some patients reporting mild dryness. Vision recovery is rapid and patients are often back to work in 2 or 3 days after the surgery. My patients who have received [LASIK] have been extremely pleased with the results of their procedures.

It is important for people in their 40's to note the following: Unless your surgeon modifies your final prescription to be less than 20/20 at distance in one or both eyes, glasses will be needed to assist in closework and reading with any of the aforementioned refractive procedures. For more information on the reasons for this, please read more on PRESBYOPIA