Abstract
Abstract: :
Purpose: To evaluate the morphology of the parapapillary region of the optic nerve head in an unselected population group in South India. Methods: The study included 70 subjects forming a population based sample, selected in a random manner. Mean age was 47.5 +/- 8.7 years, mean refractive error measured -0.07 +/- 1.11 diopters (range, -4.50 to +2.50 diopters). Optic disc slides were morphometrically analyzed. Results: Mean area of alpha zone of parapapillary atrophy measured 0.84 +/-0.29 mm2. Alpha zone occurred in 69 (98.6%) of the subjects and was significantly largest in the temporal horizontal sector followed by the temporal inferior sector, the temporal superior sector, and finally the nasal sector. Mean area of beta zone of parapapillary atrophy measured 0.13 +/- 0.38 mm2. Beta zone occurred in 8 (11.4%) of the subjects. Alpha zone was significantly (p<0.001) larger and occurred significantly more often than beta zone in all sectors. Retinal arterioles and venoles were wider in the temporal inferior disc arcade and the temporal superior arcade than in the nasal superior arcade and the nasal inferior vessel arcade. In spatial correlation with the distribution of the retinal vessels, visibility of the retinal nerve fiber layer was significantly better in the inferior temporal arcade and the temporal superior arcade than in the nasal superior arcade and the nasal inferior vessel arcade. Conclusion: The parapapillary region of the optic nerve head including the regional distribution of the retinal nerve fiber layer visibility, the spatial relationship between retinal nerve fiber layer visibility, retinal arteriole diameter, and neuroretinal rim shape, and frequency, size and regional distribution of alpha zone and beta zone of parapapillary atrophy do not markedly differ between South Indians and Caucasians.
Keywords: 498 optic disc • 363 comparative anatomy • 430 imaging/image analysis: clinical