It is a surgical procedure carried out by using an excimer laser to permanently change the shape of the anterior central cornea by removing a small amount of tissue from the corneal stroma beneath the epithelium. Excimer lasers are pulsed gas lasers that emit ultraviolet light. The procedure changes the corneal curvature and thus corrects refractive errors (Myopia, hyperopia & astigmatism), allowing light to be properly focused by the cornea on the retina for clear vision. Photorefractive keratectomy should not be confused with radial keratotomy which is an older surgical procedure used to correct myopia. Pre-OperationPatient is properly educated on procedure and signs an informed consent. A thorough eye examination is carried out and general health and medical history is properly assessed.
Operation Procedure
The surgery is performed under local anesthesia, one eye at a time and takes approximately 5-15 minutes per eye. After anesthetic drops are used to numb the eyes, an instrument called a lid speculum holds the eyelids open. The surgeon then removes the central area of the corneal epithelium with an alcohol solution. With the alcohol solution on the eye, a blunt surgical instrument is used to remove the layer. The excimer laser is used to apply computer controlled pulses of cool ultraviolet light to reshape the cornea by removing microscopic amounts of tissue in a precise pattern. This process is called ablating. The lasers are centered on the patient’s visual axis and automatically pause when eyes move out of range. Ablating continues after eyes are re-centered.
Post Operation
The surgeon then inserts a bandage contact lens after the procedure in both eyes to protect the cornea as the epithelium grows back in about 4-5 days. Patient is advised to rest eyes and topical antibiotics, anti-inflammatory as well as pain medications are prescribed to minimize swelling and discomfort and hasten healing. With destruction of Bowman’s membrane may lead to UV damages and increased sensitivity in first few days, hence patient advised to wear UV protection sunglasses. It may take up to a month or longer for patient to achieve best vision
Indications for PRK
For one to be eligible to undergo the surgical process he or she should be an adult above the age of 18 years because at this age vision has stopped changing. The patient must have refractive error, Myopia Between -1.00D to -12.00D, Astigmatism or Hyperopia, Irregular corneal shape due to ectasia, Patient should have no significant ocular and systemic diseases and a Stable refractive error.
ContraIndications to PRK
Children who constantly have a changing prescription cannot undergo the procedure. Keratoconus patients are not eligible. Patients with Recurrent ocular diseases and Dry eyes are not eligible. Patients with systemic conditions such as Sjogren’s syndrome, collagen vascular diseases, autoimmune diseases and immunodeficiency diseases are not eligible for this procedure.Pregnant and nursing mothers and Patients on certain medications which can all cause dry eyes are also not eligible for the condition.
Complications that may arise
Though PRK can be a resort for patients who would like to do away with their spectacles and lenses, some complications can arise from this procedure; Patient may end up being over or under corrected and vision would have to be improved with glasses, contact lenses or another surgery. Patient may develop glare, starbursts and haloes around lights especially at night leading to poor night vision. Corneal Scarring may also occur. Dry eyes may result post-operation. There may be Cloudiness of the cornea and Corneal infections.
REFERENCES
R. Paschotta, Field Guide to Lasers, SPIE Press, Bellingham, WA (2008).
Natasha Herz, MD, Photorefractive Keratectomy.
Jackson W.B (2004) Photorefractive Keratometry: Indications, Surgical Techniques, Complications and Results. In: Billie J.F, Harner C.F.H, Loesel F.F (eds) Aberration-Free Refractive Surgery. Springer, Berlin, Heidelberg.
Brian S. Boxer Wachler, MD (2017) PRK Laser Eye Surgery: What is PRK And How Does It Differ From LASIK?, Stein R, Stein H, Cheskes A, Symons S. Photorefractive keratometry and postoperative pain. American Journal of Ophthalmology.1994
Benjamin J.B, Borish’s Clinical Refraction, Second edition, Butterworth Heinemann Elsevier, St. Louis, Missouri.
https://www.allaboutvision.com/visionsurgery/prk.htm.
https://www.aao.org/eye-health/treatments/photorefractive-keratectomy-prk
https://eyewiki.aao.org/Photorefractive_Keratectomy
What is 
AIMS AND OBJECTIVES
To reduce or prevent vision loss through diseases such as glaucoma, cataract and refractive errors.
To enlighten the majority of the Ghanaian population about the importance of proper visual care.
To conscientize people on the need for regular eye checks
To get more people to have their wards screened within the Critical periods of a Child’s Vision Development; thus from ages 3 to till about 10 years.
To help the blind and people with low vision live a better life within the society through education of the general public to stop stigmatization.
To help in the fight of extreme poverty that puts the health of people at risk
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