Optic disc topographic measurements after pupil dilation

Purpose: To determine the effect of pupil dilation on topographic optic dis c parameters measured with confocal scanning laser ophthalmoscopy. Design: Prospective, comparative, observational case series. Participants: Thirty-eight subjects (25 glaucoma patients, 5 glaucoma suspe cts, and 8 normal subjects) representing a range of lens opacities particip ated in this study. Methods: Topographic optic disc parameter measurements were obtained before and after pupil dilation with a confocal scanning laser ophthalmoscope (He idelberg Retina Tomograph). Cataract severity was measured with the LOGS ii i grading system, image quality was assessed using the standard deviation o f the mean topography image and an image quality score. Multiple regression techniques were used to evaluate the effect of image quality, cataract den sity, and pupil size on the change in topographic parameters after dilation . Main Outcome Measures: Topographic optic disc parameter measurements. Results: With dilation, mean change in most topographic optic disc paramete rs was not significantly different from zero. Changes in topographic optic nerve parameters tended to be relatively small when undilated images were o f good quality and larger in images of relatively poor quality. The stronge st predictor of the absolute value of change in topographic optic disc para meters was the standard deviation of the undilated mean topography image. Conclusions: When confocal scanning laser ophthalmoscope images are of good quality, topographic optic disc parameter measurements obtained with a dil ated pupil are similar to those obtained with an undilated pupil. However, caution should be exercised when interpreting information from poor quality confocal scanning laser ophthalmoscopic images.