PRK stands for Photorefractive Keratectomy. It is a form of advanced surface ablation which reshapes the cornea and corrects any refractive error without creation of a flap.
During PRK surgery, the layer of epithelium is gently removed and a corrective laser is then applied to reshape the cornea to correct any refractive error. The epithelium is then allowed to heal, restoring visual clarity.
Benefits of PRK include:
- Freedom from glasses and contact lenses
- No risk of flap related complications e.g. Flap dislocation, flap striae, epithelial ingrowth
- Tissue saving as none of the corneal tissue is used for flap creation
- May be more suitable in patients with thin corneas
- May have less dry eyes compared with LASIK
A thorough assessment should be done before proceeding with any laser vision correction. In general, a suitable candidate for PRK surgery includes patients who:
- More than 18 years old
- Healthy corneas
- Stable vision and refractive errors
- Keen to be free of glasses or contact lenses
- Keen to avoid LASIK flap related complications
- Understands the initial discomfort and longer recovery period
PRK surgery has a different recovery profile compared with LASIK. In PRK, some slight discomfort can be expected in the initial 3-5 days. A special contact lens is placed to aid healing and reduce discomfort. Antibiotic and steroid eye drops are given to prevent infection and reduce inflammation during the recovery period. Vision tends to stabilise over 3 months.
Risks of PRK surgery include:
- Glare and halos
- Dry eyes
- Vision fluctuation
- Under or over-correction
- Corneal ectasia
Recovery from PRK surgery takes slightly longer with many resting for 3-5 days before returning to work. This time off needed varies from each individual as each person heals differently. During this period of recovery, a medical certificate is issued cover any absence from work.
During each follow up consultation after PRK surgery, the recovery process is assessed and advise given on when returning to exercising is suitable. Most patients are able to return to running, jogging and gyming within a week. Swimming should be avoided during the early recovery period.
PRK surgery itself is painless due to the numbing eye drops given before surgery begins. After PRK surgery, there may be some discomfort in the initial 3-5 days of recovery. A special contact lens is placed to aid healing and reduce this discomfort.
Significant improvement of vision is expected after PRK surgery compared to the previous unaided vision without glasses or contact lenses. About 99% will no longer need glasses or contact lenses to meet legal requirements for driving.
During PRK surgery, you will be given a target light to focus on. This may be a blinking green or red light. Focusing on this target light keeps your eyes perfectly aligned for the corrective laser to be accurately applied.
Modern day lasers come equipped with an eye tracker which can track your eyes in up to 7 dimensions. Any movement of the eye out of the defined treatment zone instantly stops the laser from firing until the eye is properly positioned again. Gentle blinking during PRK surgery is acceptable as long as there is no effort to tightly squeeze the eyelids closed.
After PRK surgery, it is important to avoid eye rubbing and to keep the prescribed eye drops going as planned. Goggles are given and should be used at night to prevent eye rubbing during sleeping hours.
In the early recovery period, there may be some mild haze that can be seen under the microscope after PRK surgery. This tends to fade with time as the eye heals. No scarring is usually seen after full recovery.
PRK surgery is able to treat hyperopia (long-sightedness), myopia (short-sightedness) and astigmatism.
During an assessment, a detailed history will be taken from you and specialised test to gather data on suitability will be done. This includes checking your visual acuity, refraction, cycloplegic refraction, corneal thickness, corneal topography, pupillometry, eye anterior segment examination, dilated fundus examination. Based on the assessment results, Dr Val Phua will then have a detailed discussion on the various options for laser vision correction and recommend a suitable treatment to meet your vision goals.
There is a role for PRK surgery in treating presbyopia and achieving glasses freedom. This is in the form of monovision where one eye is corrected for distance vision and the other eye corrected for near vision. Patients may simulate this with a trial of contact lenses before undergoing PRK surgery.