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Optic disc morphology in south India: the Vellore Eye Study
J B Jonas1, R Thomas, R George
1Department of Ophthalmology, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Germany. Jost.Jonas@augen.ma.uni-heidelberg.de
The British Journal of Ophthalmology
|January 25, 2003
Summary
Optic nerve head morphology in South Indians is similar to white populations, with no significant differences in key parameters like optic disc area or neuroretinal rim area. Absolute optic disc dimensions may be the only exception.
Area of Science:
- Ophthalmology
- Optometry
- Anatomy
Background:
- The optic nerve head (ONH) is crucial for vision, and its morphology can indicate various ocular conditions.
- Understanding ONH morphology in diverse populations is essential for accurate diagnosis and disease management.
Purpose of the Study:
- To evaluate the optic nerve head morphology in an unselected South Indian population.
- To compare these findings with existing data from white populations.
Main Methods:
- A population-based sample of 70 South Indian subjects was randomly selected.
- Morphometric analysis of optic disc slides was performed.
- Key parameters including optic disc area, neuroretinal rim area, and cup-to-disc ratios were measured.
Main Results:
- Mean optic disc area was 2.58 mm², independent of age and refractive error.
- Mean neuroretinal rim area was 1.60 mm², positively correlated with optic disc and cup size.
- Horizontal cup/disc ratio (0.66) was significantly higher than the vertical ratio (0.56).
- Parapapillary atrophy zones (alpha and beta) were observed, with alpha zone being larger and more frequent.
- Optic nerve head parameters showed no marked differences compared to white populations, except possibly in absolute size.
Conclusions:
- South Indian and white populations exhibit similar optic nerve head morphology based on morphometric parameters.
- Absolute optic disc dimensions might be the primary differentiating factor between these groups.