Epithelial Healing and Visual Outcomes Using Omega-3 Therapy Before and After Photorefractive Keratectomy (PRK) Surgery

Dry eye and persistent epithelial defects (PEDS) following LASIK and PRK are one of the most common conditions encountered by refractive surgeons and their patient's today.¹-⁴ They are associated with significant clinical morbidity in patients resulting in minor problems such as discomfort, to extreme debilitation such as visual loss. There is no accepted definition of persistent epithelial defect (PED) that includes a time period of recovery. We favor the definition given in one text "… when the epithelium fails to re-grow over a defect within the expected time course.⁵ The causes of PED are diverse, with several definite etiologies' including dry eyes, limbal stem cell deficiency, diabetes mellitus and neurotrophic problems. A variety of treatment modalities have been described for PED. The elimination of predisposing associated risk remains a key factor in the management process. Therefore, to prevent and manage this common disorder it is important to have an understanding of the pathophysiology of dry eye after LASIK and PRK. This includes and understanding of the relationship and interaction between inflammation, sensory denervation and essential fatty acid pathways. Reports of clinical efficacy of anti-inflammatory therapies for treatment of dry eye disease provide direct proof of the principle that inflammation is involved in the etiology of dry eye disease. Research has shown that the omega-3 polyunsaturated fatty acids are some of the most effective natural anti inflammatory agents available. The active ingredients in omega 3, EPA ( Eicosapentanoic acid ) which is a 20 carbon omega 3-fatty acid with 5 double-bonds , and DHA ( docosahexanoic acid )which is 22 carbon omega-3 fatty acid with 6 double bond, both found in certain fish oils enhance the conversion of COX ( cyclooxygenase) to prostaglandin E3. A natural anti inflammatory agent, prostaglandin E3 competitively inhibits the effects of the arachidonic acid conversion to prostaglandin E2, a highly inflammatory substance. Prostaglandin E3 also inhibits the synthesis of TNFα and IL-1β, both of which are inflammatory leukotrienes, also by competitive inhibition.⁶ʹ⁷ By decreasing inflammation and stimulating aqueous tear production in rabbits cAMP has been shown to stimulate aqueous tear secretion in dry eye. Furthermore, by decreasing inflammation and augmenting oil and water layers of the tear film, omega-3 supplementation with fish oil rich in EPA may improve both the lipid and aqueous component of the tear film. This may improve surgical outcomes by stabilizing the tear film, reducing epithelial defects and promoting wound healing