Pain Reduction After Photoablation
Refractive surgery was first approved by the FDA in 1995 to surgically correct refractive error, and now is routinely used in daily practice by ophthalmologists . Laser in situ Keratomileusis (LASIK) is the most popular refractive surgery technique performed because of the quick recovery time and limited pain after the procedure. Not all patients that qualify for refractive surgery are good candidates for LASIK. Therefore, Photorefractive keratectomy (PRK) may be a better option for patients with epithelial basement membrane disease or inadequate corneal thickness . The most prominent drawbacks to PRK are its longer recovery time and the increased risk for ocular pain after the procedure . Multiple studies have been performed to address a way to control pain after refractive surgery. These studies looked at oral medication versus topical medication, bandage contact lenses, as well as the best time to begin a pain regimen. However, no definitive method has proved to be the most reliable for mitigating pain after surface ablation.
Dry eye is the leading cause of pain and discomfort after refractive surgery. Artificial tears, nutritional supplements such as omega 3 fatty acids and flax seed oil, lacrimal punctal occlusion, lifitegrast and topical Restasis® (Cyclosporine A 0.05%) may alleviate the symptoms of dry eye. LASIK induces neurotrophic epitheliopathy and thus causes ocular dryness. Restasis® improves the symptoms of dryness by treating underlying inflammation and enhances nerve regeneration . Studies have looked at pre-treating PRK patients with GABA-analogs such as gabapentin and pregabalin. These studies have not shown any statistical significance in reducing post-operative pain . Another controlled study showed a significant reduction of post-PRK ocular pain when pre-treating eyes with topical diclofenac, which is a non-steroidal anti-inflammatory drug (NSAID), two hours prior to surgery .
Diclofenac, or NSAIDs are often the standard medication used after PRK surgery due to its effectiveness at reducing pain. NSAIDs help prevent prostaglandin release associated with corneal trauma . Additionally, after surface ablation procedures such as laser epithelial keratomileusis (LASEK) or PRK, bandage contact lenses are routinely applied to patients’ eyes to help re-epithelialization and healing to improve comfort and reduce pain   In addition, bandage contact lenses can act as a reservoir for the medication such as NSAIDs for sustained release . Ocular pain is common during the early post-operative period after PRK. Some studies deferred pain management measures until after the procedure. A prospective, randomized, controlled study evaluated three groups: one was given a placebo, one was given pregabalin 75mg orally, and was given gabapentin 300mg orally. This study did not find any significant difference in pain control . Another study evaluated post-PRK pain control with gabapentin 300mg orally versus oxycodone and acetaminophen. In this study, the gabapentin group felt significantly less pain on the morning of the second post-operative day only . Not all studies looked specifically at oral medications to reduce pain. One study did not use any pain medications or eye drops before performing LASIK, but looked at the efficacy of one drop of topical diclofenac immediately after the procedure. The results showed patients who received diclofenac were less symptomatic four hours after the procedure . Oral analgesics can be used as a “rescue medication”  if topical eye drops are not providing adequate analgesia for post-operative pain. It has been shown that patients who used both a post-operative oral NSAID and a bandage contact lens resorted to less consumption of prescribed oral analgesics . With topical NSAIDs, there is associated risk of corneal toxicity and melting. By using a single dose approach after surgery, pain relief is provided with limited chance of corneal toxicity . Another method of postoperative pain control is topical anesthetic, which is controversial, given the risk of delayed epithelial healing with topical anesthetic. However, older studies had concluded that dilute proparacaine 0.05% or giving patients 10 drops of non-dilute tetracaine 0.5% did not extend the number of days to epithelial healing compared to patients not receiving postoperative anesthetic drops. The vast majority of refractive surgeons do not prescribe postoperative topical anesthetic.
The post-operative risk of ocular pain after corneal photorefractive surgery should be discussed with all patients. Pre-operative and postoperative topical NSAID drops such as diclofenac and ketorolac, oral gabapentin, bandage contact lenses and oral analgesics are tools available for pain management.
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