Changes in Axial Length in Patients of Acute Retinal Necrosis Undergoing Vitrectomy

To observe the changes in the axial length (AL) in patients of acute retinal necrosis (ARN) undergoing vitrectomy and investigate the correlated factors. Retrospective case series. Patients diagnosed as ARN undergoing vitrectomy with silicone oil (SO) tamponade, and with attached retina more than one year after silicone oil removal (SOR) were included. Medical records and AL measured by Zeiss IOLMaster 700 were reviewed before vitrectomy, before SOR, and one year after SOR. Residual retinal index, a parameter reflecting the residual retinal area after vitrectomy was analyzed based on the ultra-wide-field fundus imaging. The AL change (ΔAL) was calculated and clinical factors related to ΔAL were investigated. In total, 45 eyes from 45 patients were included. The AL at pre-vitrectomy and pre-SOR was 23.84 ± 1.45 and 23.53 ± 1.53 mm among all 45 eyes, with a ΔAL of 0.31 ± 0.62 mm (<i>p</i> &lt; 0.001). Among the 22 eyes with AL measured at one year after SOR, the AL at pre-SOR and one-year post-SOR was 23.82 ± 1.60 and 23.16 ± 0.79 mm, with a ΔAL of 0.67 ± 1.58 mm (<i>p</i> &lt; 0.001). After excluding highly myopic eyes, the ΔAL was 0.31 ± 0.59 mm (<i>n</i> = 42, <i>p</i> &lt; 0.001) between pre-vitrectomy and pre-SOR, and 0.22 ± 0.32 mm (<i>n</i> = 20, <i>p</i> = 0.001) between pre-SOR and one-year post-SOR. Multivariable regression analysis revealed the variable that remained independently associated with ΔAL between pre-SOR and one-year post-SOR was the residual retinal index (β = –0.568, <i>p</i> = 0.006). For ARN patients undergoing vitrectomy, AL decreased significantly both post-vitrectomy and post-SOR. The refractive shift should be considered before intraocular lens implantation.