CLINICAL SPECTRUM OF OPTIC DISC EDEMA AND ITS ASSOCIATION WITH OCT-DERIVED RETINAL NERVE FIBER LAYER THICKNESS: A CROSSSECTIONAL STUDY

Background: Optic disc edema is a final common clinical sign of disorders ranging from intracranial hypertension toinflammatory and vascular optic neuropathies. Clinical grading remains important, but spectral-domain optical coherencetomography (SD-OCT) provides a reproducible structural measure of peripapillary retinal nerve fiber layer (RNFL) swelling.The study is designed to describe the clinical and etiological profile of optic disc edema and determine the relationshipbetween Frisen grade and OCT-derived RNFL thickness. Materials and Methods: This cross-sectional observational studyincluded 60 adults with clinically confirmed unilateral or bilateral optic disc edema evaluated over 18 months at a tertiaryophthalmology center in Hyderabad. Visual acuity, color vision, pupillary responses, visual fields, fundus findings,neuroimaging when indicated, and SD-OCT RNFL measurements were recorded. Disc edema was graded clinically usingthe Frisen scale. Associations were examined using non-parametric and categorical tests, with p<0.05 considered significant.Results: Mean age was 38.30 +/- 10.43 years; 43 patients (71.7%) were women and 31 (51.7%) had bilateral involvement.Idiopathic intracranial hypertension was the leading diagnosis (33.3%), followed by optic neuritis (26.7%) and retinal veinocclusion (16.7%). Across reported Frisen grades 1, 2, and 3, mean average RNFL thickness increased from 137.93 +/-10.15 to 155.78 +/- 19.89 and 271.58 +/- 47.65 micrometers, respectively (Kruskal-Wallis p<0.001). The inferior andsuperior quadrants showed the greatest thickening. Final Frisen grade correlated strongly with average RNFL thickness(Spearman rho=0.787, p<0.001). Visual acuity varied substantially by etiology and did not track structural severityuniformly. Conclusion: OCT-derived RNFL thickness showed a strong graded relationship with the clinical severity of opticdisc edema. OCT should be interpreted alongside fundus examination, visual function, and etiological work-up rather than asa stand-alone surrogate for functional visual loss.