Global and Regional Detection of Induced Optic Disc Change by Digitized Image Analysis

Objective: To evaluate two new strategies for the detection of optic disc change within individual eyes by digitized image analysis. Methods: Eleven normal optic discs of 11 monkeys were imaged with a digital imaging system (Topcon Imagenet, Topcon Instrument Corporation of America, Paramus, NJ) at two intraocular pressures (10 and 45 mm Hg). To detect global change in the disc, we compared conventional optic disc parameters with a new optic disc parameter: mean position of the disc. To detect regional change, the 95% confidence interval for change was calculated for each data point and mapped for each disc. Results: Posterior deformation of the disc surface was detected in seven of 11 eyes using conventional parameters and in 10 of 11 eyes using mean position of the disc. Regions of posterior deformation were detected by 95% confidence interval for change mapping in all 11 discs as localized areas of confluent, posteriorly displaced points. Conclusions: Mean position of the disc outperformed conventional measurements in the detection of global optic disc change. Ninety-five percent confidence interval for change mapping may allow individual data point-based focal and regional analysis of the disc.