Purpose <p>This study aimed to identify prognostic factors for retinal detachment (RD) and final best corrected visual acuity (BCVA) in acute retinal necrosis (ARN) patients using ultrawide-field (UWF) fundus imaging.</p> Methods <p>This retrospective study included 29 eyes of 25 patients diagnosed with ARN. Clinical data, including symptom duration before presentation, initial and final BCVA, anterior chamber (AC) cell grade, and vitreous opacity grade, were collected. Based on the UWF fundus imaging, the presence of arterial obliteration and the extent of retinal necrosis were analyzed to identify risk factors for RD by categorizing patients into the RD and no RD groups.</p> Results <p>The mean final BCVA was 0.72 ± 0.77 logarithm of the minimum angle of resolution (logMAR), and RD occurred in 20 eyes (70.0%). Final BCVA showed a significant difference between the RD and no RD groups. AC cell grade was significantly associated with both RD development and final BCVA (p = 0.035, p = 0.015, respectively). Arterial obliteration, fan-shaped necrotic lesions, and greater clock hours of retinitis were significantly related to RD development (p = 0.016, p = 0.001, p = 0.018, respectively). The retinitis zone was significantly correlated with final BCVA (p = 0.007). Additionally, BCVA before and at RD diagnosis showed a significant association with final BCVA.</p> Conclusions <p>UWF imaging is useful for the prognosis prediction in ARN patients. Identifying characteristic UWF findings, such as arterial obliteration and extent of necrosis, can aid in predicting RD risk and visual outcomes, improving clinical management of ARN.</p> Key Messages <Emphasis Type="BoldItalic">What is known</Emphasis> <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Acute retinal necrosis (ARN) is a rapidly progressing inflammatory condition characterized by necrotizing retinitis and vasculitis. Retinal detachment (RD) is a common late complication of ARN, often leading to poor visual prognosis.</p> </ItemContent> </UnorderedList></p> <Emphasis Type="BoldItalic">What is new</Emphasis> <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Ultrawide-field (UWF) imaging is useful for the prognosis prediction of ARN.</p> </ItemContent> <ItemContent> <p>UWF image analysis identified arterial obliteration, fan-shaped necrotic lesions, and an increased number of clock hours affected by retinitis as significant risk factors for the development of RD in ARN.</p> </ItemContent> <ItemContent> <p>Additionally, the zone of necrotic retinitis was strongly associated with the final best corrected visual acuity (BCVA) in ARN patients.</p> </ItemContent> </UnorderedList></p>