Photoreferactive keratectomy and LASEK

Photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK) surgeries are performed to correct your vision and minimise the need for contact lenses and eyeglasses.

The main parts in the eye include:

• Cornea: Frontal covering of the eye
• Iris: Coloured part of the eye
• Pupil: Dark hole located at the centre of the iris
• Lens: Located just behind the pupil, focuses light towards the retina
• Retina: Tissue lining the inside of the back of the eye

In a normal eye, the light passes through the cornea. The cornea, which has a refractive power, bends all the light towards the pupil. The pupil focuses the light passing through it towards the retina, which converts light rays into light impulses. These light impulses are transmitted through millions of nerves to the brain where they are interpreted to tell you what you are seeing. Certain conditions can make your eyeball too short or too long or cause an irregularly shaped cornea. This affects the process of the focusing of light on the retina, thereby causing vision problems.

Your eye doctor (ophthalmologist) may recommend surgery if you have:

• Eye strain
• Headaches
• Squinting
• Blurry vision
• Eye discomfort
• Myopia or nearsightedness (close objects look clear while distant objects look blurred)
• Hyperopia or farsightedness (close objects look blurred while distant objects look clear)
• Astigmatism (both close and distant objects look blurred)

You are eligible for the surgery if you fulfil the following requirements:

• You are 18 years or older
• Your eye problem is treatable by this surgery
• Your eye prescription has not changed for a year
• Your cornea and overall eye health are good

Your ophthalmologist may not recommend this surgery if you have any of the following:

• History of eye infections
• Diseases that can prolong or affect healing after surgery, such as keratitis (inflammation of the eye) and ocular herpes (viral infection of the eye)
• Are pregnant
• Constant changes in the eye prescription
• Uncontrolled diabetes
• Advanced glaucoma (a disease affecting the nerve that connects the eye to the brain)
• Scratch on the corneal surface caused by fingernails, rubbing your eyes or makeup brushes
• Diseases such as dry eyes (a condition wherein your eye does not produce sufficient tears) that damage the cornea
• Cataract (blurry vision due to cloudy lens)

Your ophthalmologist will discuss the procedure, risks, and expectations after the surgery. People usually expect to have a perfect vision after the surgery. However, this is not always the case. You may do most of your activities without the need for contact lenses or eyeglasses. However, you may need them while performing certain activities like reading or night driving.

The ophthalmologist will conduct a detailed eye examination to make sure that you are eligible for the surgery. This screening may include tests for vision, to detect eye problems, to measure thickness of the cornea and size of the pupil. While visiting the hospital for the screening tests, the ophthalmologist may ask you to do the following:

• If you use rigid gas permeable contact lenses, discontinue wearing them at least three weeks before the eye examination or screening for surgery. All other types of contact lens need to be discontinued three days before the screening.
• Bring your current eyeglasses for the screening to review your prescription.

The following preparations are required on the day of the surgery:

• Have a light meal before visiting the hospital for surgery
• Carry all your currently used medicines
• Avoid wearing any eye makeup
• Do not wear any bulky head accessories, which can interfere with your head positioning during surgery
• If you are not feeling well on the day of the surgery, inform the ophthalmologist.

You will need to ask a friend or family member to drive you home after surgery. Take a shower before the surgery since the surgeon may ask you to not have one for a day or two after the surgery. Stop smoking before the surgery to reduce the risk of complications.

The surgery is performed under local anaesthesia, a numbing medicine to control pain in a specific area. It does not make you sleep. Both photorefractive keratectomy and LASEK surgery use a laser to remodel the cornea such that the light that enters the cornea is focused on the retina.

The procedure for photorefractive keratectomy is as follows:

• A surgeon will give you local anaesthetic eye drops to numb your eyes.
• A device called lid retainer will be placed over your eye to keep your eyelids open and prevent blinking.
• The ophthalmologist will then use a special blade, laser, brush, or alcohol solution to remove the top layer of your cornea (known as the epithelium).
• He/she will ask you to stare at a source of light so that you don’t move your eyes. Your cornea will then be reshaped with a laser, an instrument pre-programmed with the measurements of your eye. You may hear a clicking sound during this process.
• The epithelial layer removed during the procedure will grow back during the recovery period.

In a LASEK surgery, the epithelium of the cornea is not removed; instead, an alcohol solution is placed on the eye to soften the cornea. The epithelium is then rolled over to a side. After reshaping the cornea with a laser, the epithelium is rolled back to its original place.

The procedure takes about 30 minutes for completion. After the procedure, a “bandage” contact lens will be placed to protect your cornea and help it heal. You will be able to go home on the same day.

Your surgeon may recommend the following to take care of yourself after the surgery:

• You may experience blurry vision after the surgery. Your vision will get better with time. It may take a month to achieve the best vision.
• You should avoid driving until your vision is back to normal.
• Avoid showering for one to two days after surgery to prevent the entry of water into your eyes.
• You may experience eye pain for around three days following surgery. Your ophthalmologist may prescribe certain medicines or eye drops for the same.
• You may need to use eye drops to assist in healing for up to a month after the surgery. Use them as per the instruction of the ophthalmologist.
• You may need to wear sunglasses outdoors for a few days after surgery to avoid exposure to sunlight since it can damage the cornea.
• Strenuous activities can slow down the healing after surgery. Hence, you need to avoid such activities for at least a week after surgery.
• Avoid applying eye makeup for at least two weeks following surgery.
• You will need to take a break from your work for a few days to avoid straining your eyes.

When to see the doctor?

You should call the ophthalmologist immediately if you have any of the following symptoms:

• Redness of the eye
• Pain
• Discharge from eye
• Sudden blurred vision

The risks associated with this surgery are as follows:

• Clouded vision (haze): Studies have found a correlation between exposure to sunlight for extended periods after surgery and occurrence of clouded vision. It may occur within the year following surgery and will gradually clear up thereafter. It occurs more commonly in people with severe nearsightedness.
• Glare: Some people may have increased sensitivity to bright light.
• Vision problems at night: Some people may experience halos, i.e., a shimmering circle around sources of light, such as street lamps or headlights.
• Double vision: It usually occurs in one eye.
• Regression: It may occur either due to regrowth of cells in the reshaped area or thickening of the treated area anytime up to two years after surgery.
• Astigmatism: Few people develop new astigmatism after surgery.
• Unsuccessful procedure: It refers to the risk of under-correction or overcorrection of your vision. Your vision may also get worse than what you had with contact lens or glasses before surgery.
• Rare complications: These include ulcers on the cornea, infection, increased pressure inside the eye, and glaucoma. 

The ophthalmologist may ask you to visit the hospital multiple times throughout the year following the surgery to examine your eyes.

Disclaimer: The above information is provided purely from an educational point of view and is in no way a substitute for medical advice by a qualified doctor.