The Twilight Zone Where Margins Are Blurred: A Retrospective Analysis of Unilateral and Bilateral Optic Disc Swelling in a Tertiary Center in Malaysia

Background To analyze the etiology of optic disc swelling (ODS) and compare the clinical features between non-arteritic anterior ischemic optic neuropathy (NA-AION) and optic neuritis (ON) at our center from January 2019 to January 2020. Methodology Clinical records of all patients who presented with ODS between January 2019 and January 2020 were reviewed. The collected data were analyzed using IBM SPSS Statistics for Windows (Version 23.0, IBM Corp., Armonk, NY, USA). Results A total of 70 eyes among 47 patients were included in this review. There were 24 patients (51%) who had unilateral ODS, while 23 patients (49.0%) had bilateral ODS. The most common etiology of unilateral ODS was ON (45.7%), NA-AION (25%), and neuroretinitis (12.5%). Among bilateral ODS, the most common cause was papilledema (30.4%), hypertensive retinopathy (21.7%), diabetic papillitis (13.1%), and optic disc drusen (13.1%). Among unilateral ODS, the mean onset age was significantly older in NA-AION cases than that in ON cases (57.5 years vs. 40.3 years, P = 0.016). Ocular pain was a significant clinical finding observed in ON cases (54.5%) and none in NA-AION cases (P = 0.043). Although there was no significant difference in the initial visual acuity (VA) between NA-AION and ON, the final VA was significantly improved in ON compared to NA-AION (0.31 ± 0.34 vs. 1.14 ± 1.00, P = 0.029). Conclusions Many differential diagnoses must be considered when a patient is presented with ODS. With the increased prevalence of hypertension and diabetes in Malaysia, it is not a surprise that both hypertensive retinopathy and diabetic papillitis together accounted for one-third of the bilateral ODS patients.