Abstract
Abstract: :
Purpose:To investigate the relationship between optic nerve parameters measured by a digital stereoscopic imaging system and Humphrey Visual Field (HVF) classification. Methods:Optic nerves of normal and glaucoma patients were photographed using a digital stereoscopic camera system (Discam, Marcher, Ltd, U.K.). Discam provides actual topographic measurements of the optic nerve by factoring in axial length measurement determined by a motorized charged coupled device (CCD). One eye of each patient was randomly selected for analysis. Subjects performed HVF (SITA standard, 24-2). Ocular axial lengths were recorded by A-scan ultrasound to calibrate that measured by Discam. HVF were classified as normal vs. abnormal, and by pattern defect as defined by the Ocular Hypertension Treatment Study. Discam optic nerve parameters were compared to HVF classification as well as to mean deviation (MD) and pattern standard deviation (PSD). Results:Optic nerve images were obtained from 12 normal and 28 glaucoma patients using Discam after images from 2 pseudophakic subjects were excluded due to poor quality from capsular interference. Mean age for normal subjects was 58 ± 14 years and for glaucoma subjects was 64 ± 13 years. Median visual acuity was 20/20 (range: 20/15-20/50). Median level of lens opacity was trace nuclear sclerosis (range: clear to +3 NS). Subjects with abnormal HVF classifications had significantly different optic nerve parameters measured by Discam (CDR-V, CDR-H, CDR-Area, rim area, superior and inferior temporal rim ratio [all P<0.001]; cup area [P=0.002]) in comparison to subjects with normal HVF. No significant difference existed when Discam parameters were evaluated according to pattern defect. For glaucoma subjects, a significant correlation was found between optic nerve parameters (CDR-V, CDR-H, CDR-Area, cup area, rim area, superior and inferior temporal rim area) and MD as well as PSD. Axial lengths measured by Discam and A-scan ultrasound were strongly correlated [r=0.63,P<0.001]. . Conclusion:The Discam optic nerve imaging system provides a quantitative description of the optic nerve that may be useful in assessing optic nerve damage in glaucoma patients.
Keywords: 498 optic disc • 430 imaging/image analysis: clinical • 624 visual fields