Changes in lamina cribrosa and prelaminar tissue in anterior ischemic optic neuropathy

Abstract

PurposeTo determine changes in lamina cribrosa (LC) and prelaminar tissue in patients with unilateral non‐arteritic anterior ischemic optic neurophaty (NAION) using enhanced depth imaging (EDI) spectral domain optical coherence tomography (SD‐OCT).MethodsSeventeen eyes of 17 patients with NAION were prospectively studied. SD‐OCT scans using EDI technology were obtained at the acute episode and at two and six months after the ischemic event. The OCT device was set to image a 15x10 degree vertical rectangle centered on the optic disc. The scan in LC was seen clearliest was selected for analysis. The vertical distances from three equidistant points on the reference line (Bruch's membrane opening‐BMO) to the anterior prelaminar tissue surface, and to the anterior and posterior surfaces of the LC were measured.ResultsAt diagnosis, mean prelaminar tissue was significantly thicker and anterior LC surface more posteriorly placed in NAION eyes than in non‐involved eyes. During the follow‐up, in NAION eyes there was a significant prelaminar thinning and an anterior LCreversal (P = 0.001 and P = 0.002 at 2 and 6 months respectively). BMO significantly reduced during follow‐up (P = 0.008 and P = 0.034 at 2 and 6 months respectively). Both prelaminar tissue thickness and BMO changes correlated with retinal nerve fiber layer thickness measurements.ConclusionsOHN is a dynamic structure that undergoes biomechanical changes in eyes suffering NAION. A significant prelaminar tissue thickening and posterior lamina cribrosa displacement occurred during the acute ischemic optic neuropathy, that reverse as the edema resolves.