✍️ reshaping of the corneal surface following removal of the epithelium.
✍️ Excimer laser is applied directly to Bowman’s layer and removes this layer and anterior stroma.
✍️ previously good for low myopia and hypermetropia.
✍️ Large PRK myopic ablations were associated with increased risk of post-operative corneal haze.
✍️ With intraoperative MMC, larger ablations are now possible without post-operative haze.
✍️PRK Range
☝️myopia from – 0.50 D to – 12.00 D
☝️hypermetropia up to +6.00 D
☝️ astigmatism up to 5.00 D.
✍️ PRK is the treatment of choice for
☝️ thin corneas.
☝️ Corneas with epithelial irregularities, superficial scars and dystrophies.
☝️ very flat or very steep corneas.
☝️ Eyes with increased risk of trauma such as military personnel and contact sports players.
☝️ dry eyes.
☝️ Patients who had complication from LASIK in fellow eye.
✅ PRK Method
✍️ Corneal epithelium is removed in area of planned treatment (ablation of epithelium is very uneven with excimer laser).
☝️ mechanically (blade or rotating brush)
☝️ chemically (20% ethanol)
☝️ laser itself on PTK mode.
✍️ the size of the ablation zone (optical zone) depends on the type of ametropia
☝️ larger optical zones necessary for hypermetropic corrections than myopic corrections).
✍️ Following ablation, CL is inserted until epithelial defect healed.
✍️ Post-operative topical antibiotics and steroids given.
✅ PRK Advantages
✍️ safe
✍️ more ablation possible in thin corneas since no flap required
✍️ removal of all complications related to flap creation in LASIK.
✅ PRK Disadvantages
✍️ post-operative pain for 2–4 days .
✍️ Slow recovery
✍️ slow refractive stability.
✍️ Wound healing variability
✍️ haze formation minimized by MMC
✍️ Long post-operative drop regimen.