Photorefractive Keratectomy

Photorefractive keratectomy(PRK) is a refractive eye surgery that is performed to improve vision by correcting refractive eye errors.

Refractive eye errors are disorders in which the eyes cannot refract/bend the light properly. PRK might also reduce and sometimes completely negate the need for eyeglasses or contact lenses.

PRK uses laser technology to treat vision problems by changing the shape of the cornea. This improves the way light rays are focused on the retina. PRK may be needed if one is diagnosed with the following eye issues:

Myopia(nearsightedness)
Hyperopia(farsightedness)
Astigmatism(shape of the eye causes blurry vision)

Eligibility for PRK

Photorefractive Keratectomy is a revolutionary technique to treat refractive eye errors, however, it is not for everyone.

Certain criteria need to be met to have a PRK. Besides consulting a certified ophthalmologist, one needs to:

Be 18 years or older
Have healthy eyes and corneas
Have an eye prescription that hasn’t changed in the last year
Have a realistic expectation about the outcome of this procedure

Some people cannot receive this surgery if they:

Have a changing refractive eye error
Have corneal abrasions or scarring
Have advanced glaucoma
Are pregnant/breastfeeding
Have infected eyes, blepharitis, dry eyes
Have skin diseases, or any disease that affects healing
Have allergies
Have uncontrolled diabetes

PRK is an outpatient surgery that can be performed in an outpatient eye center by a team of ophthalmologists and other health care workers.

Preparations for PRK

the surgery. During this session, the medical history of the patient is evaluated and the eyes are thoroughly examined to measure the following:

Pupil size.
The refractive error.
Cornea.
The general health of the eyes.

Any queries or doubts regarding any step of the procedure shall be discussed with the eye surgeon at this point. Then a preferred date is scheduled for the PRK procedure.

To prepare for the operation day, one should stop wearing rigid gas permeable contact lenses, if any, at least three weeks before the date of the screening visit. Other types of contact lenses should be stopped at least three days before evaluation by the eye surgeon. And, for the eye prescription to be reviewed, one should bring their current glasses to the eye center.

On the surgery day, eat a light meal, wear comfortable clothes and avoid any makeup or accessories. If there’s any health concern or discomfort, discuss it with the treating eye surgeon immediately.

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PRK Procedure

The Photorefractive Keratectomy procedure will only take about 10-15 minutes. The treating surgeon will take the following steps to perform the procedure:

Anesthetic eye drops are used to numb the eye.
An instrument/holder is placed in the eye to hold the eyelid and stop the patient from blinking and the patient is asked to focus on the light.
The surgeon will then remove the outer layer of the cornea(corneal epithelium) using a brush, blade, laser, or alcohol solution.
The surgeon will then use an excimer laser to apply computer-controlled pulses of light energy to reshape the cornea.
Next, the surgeon will administer nonsteroidal anti-inflammatory eye drops, antibiotic drops, and steroid drops.

Recovery

After the completion of the procedure, a clear bandage contact lens is usually inserted at the end of surgery to reduce irritation during the healing process and to protect the cornea as the epithelial layer grows back over the next 3-4 days. This also helps decrease the mild to moderate discomfort experienced during this time such as foreign body sensation in the eye. Patients can usually go home on the same day, but someone else should drive them home. Patients may experience tearing, sensitivity to light, and a moderate amount of blurred vision which may prevent driving during the first 3 days. Such difficulties are particularly felt on the second and third days after the procedure, but improve greatly by the fourth and fifth days as the surface layer of the cornea grows back.

The eye surgeon may advise taking off from work for a few days as any strenuous activities may delay the healing. During this time, chilled lubricating and medicated drops are prescribed to reduce discomfort, heal the cornea, and decrease the risk of scar formation and infection.

The cornea heals from the edges towards the center. As the corneal epithelium regrows it forms a “ridge” of epithelium across the pupil where the healing tissues meet. This ridge usually has formed by the fourth or fifth day, and it is safe to remove the bandage contact lens. The vision is much improved by this time, generally ranging between 20/30 and 20/50, depending on the magnitude of the corrective treatment done.

As the ridge of epithelium smoothes out over the next 4-6 weeks, the vision will gradually improve. The correction is usually considered to be stable by 3-6 months after surgery, at which time an enhancement could be considered if necessary. After PRK, the ophthalmologist will advise wearing sunglasses while going outside as sun exposure can lead to corneal scarring after surgery, causing vision problems.

One may experience blurred vision for a few days immediately after the PRK procedure, however as the healing progresses, vision gradually improves over time.

Risk and Benefits associated with PRK

Risks

As with any surgical procedure, PRK also comes with risks of potential complications. These possible problems include:

Glare and halos around lights, particularly at night
Corneal scarring
Corneal haze/ cloudiness of the cornea
Corneal infection
Light sensitivity
Regression, which means treatment becomes less effective over time
Delayed healing

PRK can result in undercorrection or overcorrection of the vision. However, most of these can be easily corrected with glasses, contact lenses, or additional laser surgery. The majority of these complications can be treated without any loss of vision. However, very rare serious problems may arise that include:

Vision worse than before PRK, even with glasses or contacts (also known as loss of best-corrected vision)
Blindness

It is really important to have realistic expectations about what PRK can and cannot achieve. PRK may not be ideal for people who are fine with wearing contacts or glasses. Hence, a detailed discussion with the ophthalmologist helps to weigh the benefits and risks of this procedure.

Benefits

Photorefractive keratectomy is an effective laser eye surgery to improve vision by correcting refractive eye errors. There are many advantages of it, that include:

Accurate correction of nearsightedness. Approximately 90% of PRK patients have 20/20 vision without glasses or contact lenses one year after the surgery. Over 95% have 20/40 or better (without glasses or contacts).
PRK may be preferable to other laser surgeries such as LASIK in certain patients with thinner corneas or with corneal surface irregularity since PRK disrupts less corneal tissue than a comparable LASIK surgery.
This procedure is technically less complex and utilizes the same modern laser treatment systems as LASIK. Hence, refractive surgeons are increasingly preferring PRK to LASIK.

PRK vs LASIK: Similarities and Differences

Both LASIK(Laser in situ keratomileusis) and PRK are eye surgeries that are performed to correct refractive eye errors by reshaping the cornea. Both of these procedures utilize lasers and take about the same time to perform.

With LASIK, the surgeon first creates a flap out of the corneal epithelial layer with a bladeless laser. The flap is then moved out of the way and reshaping of the underlying cornea is done. The flap remains attached to the cornea and is placed back as before after the procedure is completed. Whereas in PRK, the eye surgeon removes the superficial corneal epithelium and proceeds to reshape the cornea. The epithelium then regrows over time. Hence, LASIK surgery requires a thicker cornea and the best outcomes are possible if the problem is mild to moderate.

As far as side effects and recovery are concerned, PRK is associated with more side effects and a longer recovery time than LASIK. However, success rates are similar in both of these surgeries.

PRK and LASIK are both considered safe and effective procedures that improve vision significantly. However, deciding between these two procedures can be challenging unless there’s a clear indication or requirement for a particular procedure. Patients with thinner corneas or poorer vision benefit more from PRK. And, those who wish to have a quicker recovery may proceed for LASIK.

Summary

A photorefractive keratectomy (PRK) is a simple surgical procedure with a short recovery time. It is effective in correcting refractive eye errors such as nearsightedness, farsightedness, or astigmatism. It is extremely important to have realistic expectations out of this surgery. Patients may still require glasses or contact lenses after the surgery. Presbyopia(age-related loss of near vision) cannot be corrected with this procedure. Hence, a thorough discussion with the ophthalmologist about any concerns and options is warranted as soon as any eye problems are experienced.

FAQ

What is Photorefractive Keratectomy?

Photorefractive keratectomy(PRK) is a refractive eye surgery that is performed to improve vision by correcting refractive eye errors. Refractive eye errors are disorders in which the eyes cannot refract/bend the light properly. PRK might also reduce and sometimes completely negate the need for eyeglasses or contact lenses. PRK uses laser technology to treat vision problems by changing the shape of the cornea. This improves the way light rays are focused on the retina.

Why is photorefractive keratectomy (PRK) performed?

PRK is performed to treat the refractive errors of the eye with the use of excimer laser by reshaping the cornea. If one suffers from myopia(nearsightedness), hyperopia(farsightedness), astigmatism(blurred vision due to the shape of the eye), then PRK can be the choice of treatment.

What are the criteria for PRK?

Besides consulting a certified ophthalmologist, one needs to meet the following criteria: ● Be 18 years or older ● Have healthy eyes and corneas ● Have an eye prescription that hasn’t changed in the last year ● Have a realistic expectation about the outcome of this procedure

Is a photorefractive keratectomy (PRK) an outpatient or inpatient surgery?

Photorefractive keratectomy is an outpatient eye surgery that can take place in an outpatient eye center.

How long does the photorefractive keratectomy (PRK) procedure last?

The PRK procedure only takes about 10 to 15 minutes.

What kind of healthcare provider performs a photorefractive keratectomy (PRK)?

Photorefractive keratectomy is usually performed by a team of health care workers that may include : ● Ophthalmologists (who study and treat eye diseases). ● Ophthalmic surgeons. ● Nurses. ● Optometrists (healthcare providers who specialize in the eyes in general). ● Technicians.

What are the preparations needed for PRK?

To prepare for the surgery, one should get an appointment with an ophthalmologist to discuss the procedure in detail. An eye doctor will explain what should be expected before, during, and after the surgery. During this session, the medical history of the patient is evaluated and the eyes are thoroughly examined to measure the following: ● Pupil size. ● The refractive error. ● Cornea. ● The general health of the eyes.

Will I be asleep during the procedure?

No, the patient will remain awake during the PRK procedure. The eye surgeon will use anaesthetic drops to numb the eyes.

What happens during the photorefractive keratectomy (PRK) procedure?

After giving the numbing eye drops, an instrument/holder is placed in the eye to hold the eyelid and the patient is asked to focus on the light. The outer layer of the cornea(corneal epithelium) is then removed using a brush, blade, laser, or alcohol solution. An excimer laser is then used to apply computer-controlled pulses of light energy to reshape the cornea. Next, the surgeon will administer nonsteroidal anti-inflammatory eye drops, antibiotic drops, and steroid drops.

When will I be able to go home after the PRK procedure?

Patients usually can go home on the same day, but someone else should drive them home.

What is PRK surgery recovery like?

After the surgery, a clear bandage contact lens is inserted to reduce irritation during the healing process and to protect the cornea. The eye surgeon may advise taking off from work for a few days if necessary. Sunglasses are mandatory while going outside as sun exposure can lead to corneal scarring after surgery, causing vision problems.

How long will it take for the vision to improve after PRK?

Blurred vision may be experienced for a few days, however, vision gradually improves over time as healing progresses.

Is photorefractive keratectomy (PRK) painful?

No, as the eyes will be numbed so that the patient doesn't feel anything. After the surgery, it can be painful for a few days, so medicated lubricating eye drops are prescribed to reduce discomfort, heal the cornea, and decrease the risk of scar formation and infection.

What are the complications of Photorefractive Keratectomy?

As with any surgical procedure, PRK also comes with risks of potential complications. These possible problems include: ● Glare and halos around lights, particularly at night ● Corneal scarring ● Corneal haze/ cloudiness of the cornea ● Corneal infection ● Light sensitivity ● Regression, which means treatment becomes less effective over time ● Delayed healing

What is the success rate of PRK surgery?

Photorefractive keratectomy is very effective in correcting of nearsightedness. Approximately 90% of PRK patients have 20/20 vision without glasses or contact lenses one year after the surgery. Over 95% have 20/40 or better (without glasses or contacts).

What is the difference between PRK and LASIK?

Both LASIK(Laser in situ keratomileusis) and PRK are eye surgeries to correct refractive eye errors by reshaping the cornea using laser technology and take about the same time to perform. With LASIK, the surgeon first creates a flap out of the corneal epithelial layer which is then moved out of the way and reshaping of the underlying cornea is done. The flap is then placed back as before after the procedure is completed. Whereas in PRK, the superficial corneal epithelium is removed and the cornea is reshaped. The epithelium then regrows over time.

Is PRK better than LASIK?

PRK may be preferable to other laser surgeries such as LASIK in certain patients with thinner corneas or with corneal surface irregularity since PRK disrupts less corneal tissue than a comparable LASIK surgery. This procedure is technically less complex and utilizes the same modern laser treatment systems as LASIK. Hence, refractive surgeons are increasingly preferring PRK to LASIK.

Summary