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Asymmetry in optic disc parameters: the Blue Mountains Eye Study
L S Ong1, P Mitchell, P R Healey
1Department of Ophthalmology, the University of Sydney, Westmead Hospital, NSW, Australia.
Investigative Ophthalmology & Visual Science
|April 2, 1999
Summary
Vertical cup-to-disc ratio asymmetry is higher in open-angle glaucoma (OAG) patients, but asymmetry alone is not a reliable indicator for OAG diagnosis. Further research is needed to understand OAG progression.
Area of Science:
- Ophthalmology
- Optometry
- Glaucoma Research
Background:
- Optic disc parameters are crucial in diagnosing glaucoma.
- Asymmetry in these parameters may indicate underlying ocular conditions.
Purpose of the Study:
- To investigate vertical optic disc parameter asymmetry in normal, ocular hypertension (OH), and open-angle glaucoma (OAG) groups.
- To determine if asymmetry is a useful diagnostic marker for OAG.
Main Methods:
- Analysis of optic disc photographs from 3654 participants (aged 49-97) in the Blue Mountains Eye Study.
- Measurement of vertical disc diameter and vertical cup-to-disc ratio asymmetry in masked evaluations.
Main Results:
- Vertical disc diameter asymmetry showed no significant difference across normal, OH, and OAG groups.
- Vertical cup-to-disc ratio asymmetry was significantly higher in OAG patients compared to normal and OH groups.
- A cup-to-disc ratio asymmetry of 0.2 or more was observed in 24% of OAG patients versus 1% of OH and 6% of normal subjects.
Conclusions:
- While vertical cup-to-disc ratio asymmetry differs between OAG and other groups, it is not sufficiently diagnostic on its own.
- Asymmetry alone is not a reliable tool for identifying individuals with OAG.