Abstract
Purpose: :
To define the normal range of asymmetry in optic disc parameters in African-Americans by using the HRT-derived Rim Area-Disc Area Asymmetry Ratio (RADAAR).
Methods: :
This is a cross-sectional study of African-American patients recruited from the eye clinic at Howard University Hospital from July 2006-June 2008. Normal patients - defined as patients with intraocular pressures less than 22 mmHg without signs of cornea, optic disc, and retinal pathology, normal Frequency Doubling Technology (FDT) or Standard Automated Perimetry (SAP) and normal retinal nerve fiber layer by Optical Coherence Tomography (OCT)-underwent a complete ophthalmic evaluation: including biomicroscopy of the anterior segment, IOP measurements by means of Goldman tonometry, indirect ophthalmoscopic examinations, FDT for visual field screening, SAP if the FDT was abnormal, and optic disc analysis using Optical Coherence Topography (OCT) and Heidelberg Retinal Tomography (HRT). The parameters measured and analyzed by the HRT II software were the rim area and disc area of each eye. RADAAR was calculated by taking the % difference of the rim area between fellow eyes divided by the % difference of the disc area between fellow eyes.
Results: :
There were 82 eyes of 41 African American patients enrolled, with a mean age of 41.7 +/- 17.5 years. 55% were male, 45% were female. The mean IOP was 15.3 +/- 2.9 and CCT 527.4 +/- 27.0. The average RADAAR (+/- SD) was 1.80 +/- 1.5 with a range of 0.11 to 11. The median value was 1.36 with a mode of 0.75 (3/41 patients).
Keywords: optic nerve • imaging/image analysis: clinical