Photorefractive Keratectomy (PRK) Eye Procedure

Contents

 In this article, we will take a look at:

• What is photorefractive keratectomy (PRK) surgery?
• Eligibility for PRK
• PRK procedure
• Side effects of PRK surgery
• Complications of PRK surgery
• Pre-surgery guidelines for PRK
• Post-surgery guidelines for PRK
• Recovery from PRK surgery
• Cost of PRK surgery
• Results of PRK surgery
• More Topics on Opthalmology Procedures
• References

You can click on any of the links above to navigate to the section of your interest. 

What is photorefractive keratectomy (PRK) surgery? 

PRK is a type of refractive laser surgery to correct myopia short-sightedness (myopia), farsightedness (hyperopia), astigmatism (unevenly curved cornea). PRK is the predecessor to the popular LASIK procedure.

During a PRK procedure, the cornea's shape is changed so that the patient’s vision becomes less blurry.

Am I eligible or an ideal candidate or eligible for PRK eye surgery?

The PRK procedure would be a suitable procedure for you if:

• you are above 18 years of age to undergo a PRK surgery  
• You have  thin corneas
• your vision has been stable at least for one year prior to the procedure date.
• you are generally healthy, with a robust constitution, and lead an active life
•  you have mild corneal conditions or a thin cornea, and have realistic expectations from the PRK surgery along with awareness of the risks and benefits of this procedure

This surgery is not for you if:

• you are pregnant or nursing
• you suffer from eye diseases or retinal and optic nerve diseases such as keratoconus, glaucoma, cataracts, corneal disease,
• If you suffer from medical conditions such as herpes simplex, herpes zoster, autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, or Lupus, or conditions such as diabetes, arthritis, collagen vascular disease, then you are not a good candidate for PRK surgery.  
• if you take steroids or immunosuppressants or are prone to allergies or keloids.

How is the PRK eye procedure done? 

The PRK procedure differs from the LASIK procedure, in that, no flap is created in the PRK procedure. The procedure includes the following steps. 

1. At the outset of this procedure, anesthetic drops are applied in the eye to numb it.
2. An eyelid holder will be placed between your eyelids to prevent blinking and restrict any eye movement.

                  Please Note: During this procedure, scalpels are not used and neither are any incisions made. 

              3. The surgeon will carefully remove the complete upper layer of your cornea (epithelium) and then use targeted laser or excimer laser to correct and reshape the cornea. 

                   Please Note: The epithelium regenerates within 3 to 5 days. 

              4. After the surgery, a clear contact lens which acts like a bandage will be placed over your eye for 4-6 days.

              5. The same process is repeated with your other eye. 

PRK surgery is performed to correct myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. This surgery is considered to be ideal for people with thin corneas. 

What are the side effects of PRK eye surgery? 

Following the procedure, there could be irritation in the eyes, coupled with watering for at least 3-4 days. 

Other side-effects can include infections, inflammations, scarring, and dry eyes, within the first week after the surgery, when the cornea is healing. These conditions can be treated with antibiotic drops. 

Though highly rare, occasionally, in some patients irregular astigmatism may occur after PRK surgery. This can be treated with an additional minor procedure.

Another side effect that may occur is overcorrection or undercorrection of eyesight. When overcorrection occurs nearsightedness gets altered to farsightedness, and it is vice versa for undercorrection. These residual power error conditions can be corrected through enhancement or retreatment surgeries. If however, your cornea is too thin or steep the surgeon will advise you to not go in for additional surgeries and will instead prescribe you glasses or lenses to correct your vision. 

What are the possible complications of PRK surgery?

Corneal haze is another complication that can arise after a PRK surgery. This condition usually resolves itself as the eye heals, but can take from 6 months to one year, therefore doctors prefer to treat it with medication or more laser treatment. 

A more aggressive complication which is uncommon, but can occur post a PRK surgery is corneal ectasia. Corneal ectasia is an umbrella term for a group of eye disorders characterized by abnormal corneal thinning or irregular thickening from the centre of the cornea to the periphery. The most common among these disorders is keratoconus.
Corneal ectasia can occur if the cornea is too weak. 

It has been observed that corneal crosslinking treatment helps to arrest conditions such as keratoconus. In this procedure, custom-made riboflavin drops saturate the cornea, which is then activated by ultraviolet light. According to studies, this increases the amount of collagen cross-linking in the cornea thus strengthening the cornea.
This method, however, is not currently FDA approved. 

Unlike LASIK surgery, after the PRK surgery, there are no flap-related complications. 

Are there any pre-surgery guidelines to be followed before a PRK eye procedure? 

Prior to going for an evaluation by an ophthalmologist, it is recommended to stop using contact lenses for four weeks and switch to wearing glasses. Wearing contact lenses over a long period of time changes the shape of the cornea. The cornea then takes a long time to assume its natural shape.  It is similar to how a watchband leaves an imprint on the hand when worn for a long time. Therefore, an evaluation and surgery based on the cornea which has not assumed its natural shape can have negative implications. 

During the evaluation you need to discuss in depth with your doctor about whether you are a good candidate for PRK surgery, what are the alternative surgeries you can opt for, what are the risks and complications involved, what can you expect after the surgery, and what are the pre and post surgery guidelines. 

On the day of the procedure do not wear any jewellery, and do not apply any cream, and make-up, or use any perfume. You may be asked by the doctor to frequently scrub your eyelids and lashes gently, 2-3 days before the surgery, to get rid of any accumulated oil or debris.  

You need to discontinue any cold or allergy medicines at least 4 days prior to the surgery. If you take any blood thinners you need to check with the doctor whether you need to stop taking them for some time prior to the surgery. 

You will need to stop smoking and drinking alcohol 48 hours before and after the surgery. 

On the day of the surgery, you should not take insulin if you are a diabetic. You will need to arrange for a driver to take you home after the surgery. 

Are there any post-surgery guidelines to be followed after a PRK eye procedure? 

After the surgery you will be advised to:

• not rub your eyes.  
• avoid any form of strenuous exercise, such as heavy lifting, or swimming, that could result in eye injury for at least a month
• avoid driving till your vision is absolutely clear.
• wear sunglasses for a week after the surgery, even while indoors. (Ideally, glasses should be worn for the first six months after the surgery to avoid UV rays and avoid haze formation.)
• avoid applying any makeup or lotion on the face
• avoid any situation involving dirt for 7-10 days.
• not to get face wash or soap in your eyes  while washing your face, or showering (In fact, you need to keep water and shampoo away from your eyes for at least 7 days after the surgery.)
• avoid swimming and hot tubs for at least a month after the surgery.
• apply eyedrops in your eyes at regular intervals as prescribed by the doctor.

How long will it take to recover from a PRK surgery? 

The initial vision recovery period could take up to 4 days during which you will also experience mild discomfort in the eye.

You might experience sensitivity to light, which is accompanied by the feeling of tearing, or at times the feeling of a foreign body in the eye. This is the period when the epithelial layer of the cornea is regenerating. The discomfort vanishes by the fourth day. The vision, however, remains cloudy. 

It may take 4-6 weeks for your vision to become clear so that you can start performing finer activities or detailed tasks. 

After a period of six months, the vision stabilizes and becomes absolutely clear. 

It usually takes 3 - 6 months to completely recover from a PRK surgery and achieve clear vision. 

What is the cost of PRK surgery in India? 

A PRK procedure will cost anywhere between Rs. 35000 - Rs. 40000 in India. 

Are the results of PRK surgery permanent? 

In most cases, a PRK procedure is sufficient for vision correction. However, in some cases a person might not achieve the desired optimal result from the surgery, in such cases, the doctor may advise a second PRK procedure to further enhance the results. 

The PRK procedure permanently corrects the shape of the cornea, however, this does not stop the natural vision abnormalities that occur with aging. 

More Topics on Opthalmology Procedures

People interested in this topic  also read: 

• Corrective Eye Surgery Procedures: Cost & Eligibility
• LASIK (Laser-Assisted in Situ Keratomileusis)
• Epi LASIK (Epipolis Laser In Situ Keratomileusis)
• LASEK (Laser Epithelial Keratomileusis)
• PRK (Photorefractive Keratectomy)
• ICL (Implantable Collamer Lens) surgery 
• Blepharoplasty (Eyelid surgery)
• Cataract Surgery

References