Abstract
Purpose :
To study lamina cribrosa (LC) depth variation measured by spectral domain-optical coherence tomography (SD-OCT) in four optic disc phenotypes in open-angle glaucoma (OAG).
Methods :
Fifty-nine normal eyes and 180 OAG eyes were included in the study. The OAG eyes were grouped into 56 focally injured discs (FI), which were previously referred to as focal ischemic discs, 30 generalized enlargement of the optic cup discs (GE), 69 myopic glaucomatous discs (MY), and 25 senile sclerotic discs (SS) by reviewing stereo photographs. Enhanced depth imaging (EDI) OCT cross sectional scans of the optic discs were performed and multiple horizontal and vertical B-scans were obtained. The LC depth was measured by using two reference planes; Bruch’s membrane opening (BMO) and anterior sclera (AS). LC depth was defined as the length of a line perpendicular from these reference lines to the manually drawn anterior surface of the LC. Mean and maximum LC depths were measured relative to the BMO and AS references planes. LC depths were compared between normal and OAG groups, and then among normal and four glaucomatous optic disc phenotypes. LC depth differences within groups were examined as well as the overlap between them.
Results :
Mean and maximum LC depth were significantly greater in OAG group than in normal group relative to both BMO and AS reference planes (all P<0.0001). There were significant differences in mean and maximum LC depth among four glaucomatous phenotypes relative to both BMO and AS reference planes (all P<0.0001). GE group had significantly greater (P<0.001) and SS group had significantly smaller (P<0.05) mean and maximum LC depths than the other disc groups. There was a wide range of LC depth overlap between normal and SS group, and high proportion of eyes of SS group had LC depth fell into the 95% reference range (RR) of that of normal group (88.1% for the mean LC depth and 100% for the maximum LC depth relative to BMO). The GE group had small overlap range between other disc groups (95% RR: 3.3% - 26.7%) because of its great LC depth .
Conclusions :
LC was displaced posteriorly in the OAG group compared to the normal group. The LC depth was significantly different among four glaucomatous disc phenotypes. SS group had similar LC depth to the normal group.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.