Goodbye Lenses & Glasses!

Goodbye
Lenses & Glasses!

LASIK is meant to help reduce people’s dependency on glasses and contact lenses. But people, in general, lack adequate awareness about this effective vision correction surgery

By Dr Geetika Khurana
LASIK stands for Laser-assisted in-situ keratomileusis, which means using a laser underneath a corneal flap (in situ) to reshape the cornea(keratomileusis). This procedure utilizes a highly specialized laser designed to treat refractive errors, improve vision and reduce or eliminate the need for glasses or contact lenses. This laser procedure alters the shape of the cornea, which is the transparent front covering of the eye. All laser vision correction surgeries work by reshaping the corneaso that light traveling through it is properly focused onto the retina located in the back of the eye. LASIK is one of a number of different surgical techniques used to reshape the cornea.

HOW DOES LASIK WORK

During the LASIK procedure, a precise, thin hinged corneal flap is created using a microkeratome or femtosecond laser. The surgeon then pulls back the flap to expose the underlying corneal tissue, and then the excimer laser ablates (reshapes) the cornea in a unique pre-specified pattern for each patient. The flap is then gently repositioned onto the underlying cornea without sutures. The reshaping of the cornea is such that light travelling through it is focused on the retina.

 

REFRACTIVE ERRORS FOR WHICH LASIK IS USED

• Myopia (nearsightedness): In people with myopia, distant objects appear to be blurry and near objects to be clearer.
• Hyperopia (farsightedness): In people with hyperopia, near objects appear to be blurry and distant objects to be relatively clearer.
• Astigmatism: In people with astigmatism, either the corneal or lens shape is distorted, causing multiple images on the retina. This causes objects at all distances to appear blurry.

 

CANDIDATES FOR LASIK SURGERY

• Age more than 18 years
• Stable refractive error for atleast a year
• Myopia upto -13D and astigmatism upto -6D
• Adequate corneal thickness
• No Corneal ecstatic disorders
• No dry eye
• Motivated for LASIK surgery

 

RISKS AND COMPLICATIONS OF LASIK SURGERY

• Over/Under correction
• Regression of refractive correction
• Glare/Haloes
• Dry eye
• Post-surgical ectasia
• Infection

 

NON CONVENTIONAL REFRACTIVE SURGERIES

Wave front optimized LASIK

It takes into account corneal curvature and thickness, and applies laser energy in a unique fashion in the periphery of the cornea. This laser has been found to reduce the aforementioned complications such as glare, halos, and other nighttime visual aberrations that can occasionally occur with conventional treatments.

Wavefront-guided LASIK

Also referred to as custom LASIK, it is similar to conventional LASIK, except that in addition to treating a patient’s basic refractive error, specific alterations in a patient’s eye (high order aberrations) can also be treated. In wavefront-guided LASIK, special mapping is performed prior to surgery to identify any small irregularities in the patient’s optical system. When these irregularities are severe, they can affect vision quality, contrast sensitivity, and night vision. When significant irregularities in a patient’s wavefront mapping are found, wavefront-guided LASIK can be used, and the treatment will be based on the wavefront-map generated.

Laser Epithelial Keratomileusis

LASEK is similar to LASIK and PRK, but it starts with the application of alcohol to the corneal epithelium. This loosens the outermost corneal cells and allows the surgeon to move them out of the way, without removing them, for the laser procedure. After reshaping the stroma with the excimer laser, the surgeon can put a contact lens to let it heal.LASEK can be a good option for patients with thin corneas.

Epi-LASIK(Epithelial Laser in Situ Keratomileusis)

Epi-LASIK starts the way LASIK does, except the flap is thinner and made only of epithelial tissue. Once the flap is created, it is moved aside, just enough that the surgeon can reshape the stroma underneath with the excimer laser. The flap of epithelium is then replaced and covered with a contact-lens bandage to heal. Some consider Epi-LASIK a hybrid of LASIK and LASEK. Some surgeons believe Epi-LASIK is a good option because the flap exists only in the epithelium layer, and because there’s no alcohol used during the procedure.

Phakic intraocular lenses:

For patients with extreme myopia, LASIK and advanced surface ablation are not reasonable options. In these cases, a phakic intraocular lens may be used. This lens is implanted inside the eye and can effectively treat nearsightedness up to -20 diopters.

Conductive keratoplasty:

Conductive keratoplasty (CK) is a technique that can be used for the temporary correction of hyperopia or presbyopia. CK involves using radiofrequency waves in the peripheral cornea to cause peripheral corneal shrinkage and central steepening. This procedure is very safe, but its effect is often not long-lasting, and regression is common after a few years.

Intracorneal ring segments:

Intacs are approved for the correction of low myopia and for patients withkeratoconus. Intacs are micro-thin plastic segments that are implanted into the peripheral cornea in order to flatten the cornea centrally. These rings can be removed, and their effect is usually completely reversible. They are only able to correct up to -3 diopters of myopia, and visual recovery is generally slower and less predictable than LASIK.

 

MYTHS ABOUT LASIK SURGERY

1. LASIK recovery time is lengthy and extensive

Most patients are able to resume most normal daily activities within a day or two following their procedure, and while everyone heals at their pace, most patients can head back to work within two days.

2. Laser vision correction is incredibly painful

Laser eye surgery actually is virtually painless. While some patients describe feeling mild discomfort from a slight pressure or vibrating sensation, most report feeling no pain during their procedure. Anesthetic drops are used to numb the eyes just before surgery begins, and you may be given a mild sedative as well. After your procedure, your eyes may have a foreign body sensation or irritation for a few hours, but for most patients, these side effects will go away in a few hours after taking a short nap.

3. LASIK is a “cure all” for glasses and contacts

LASIK surgery was designed to help reduce your dependency on glasses and contact lenses, but it does not guarantee that you will never need them again. LASIK patients are still susceptible to presbyopia, which occurs naturally with age.

4. LASIK is a lengthy procedure

In actuality, LASIK takes minimal time and can have life changing results. The average procedure, including prep time, ranges from 60 to 90 minutes, but the laser correction itself only takes about 10 to 15 minutes.

5. Lasers used during LASIK can cut through your eye

The lasers used during LASIK emit a cool beam of light, which is not capable of penetrating your body via your LASIK procedure. Rather than burning or cutting the biological matter of your body, excimer lasers used during LASIK have a useful property where they can remove exceptionally thin layers off of the surface of your eye with almost no heating or change to the remainder of your eye, making them ideal for these delicate surgeries.

Therefore, with proper evaluation and surgical technique, LASIK surgery can help one see the beautiful world around us without glasses or contact lenses.

 

(The author is Senior Resident doctor, Army College of Medical Sciences, Base Hospital, Delhi Cantt)