Neuroretinal rim width ratios in morphological glaucoma diagnosis

Area of Science:

• Ophthalmology
• Optometry
• Medical Imaging

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Accurate diagnosis relies on detecting early optic nerve damage.
• Neuroretinal rim shape is a key indicator of optic nerve health.

Purpose of the Study:

• To assess the utility of inferior to temporal and superior to temporal neuroretinal rim width ratios in diagnosing glaucoma.
• To evaluate these ratios as objective measures of optic disc rim shape.

Main Methods:

• Morphometric analysis of optic disc photographs from 527 normal subjects, 100 ocular hypertensives, and 202 glaucoma patients.
• Exclusion of eyes with optic cup area < 0.2 mm².
• Calculation and comparison of inferior to temporal and superior to temporal rim width ratios.

Main Results:

• In normal subjects, the inferior to temporal rim width ratio was significantly higher than the superior to temporal ratio.
• Both ratios were significantly lower in ocular hypertensive and glaucoma groups compared to normal subjects.
• Despite statistical significance, the diagnostic power for both ratios was approximately 58-59%, indicating considerable overlap.

Conclusions:

• Low inferior to temporal and superior to temporal rim width ratios may suggest glaucomatous optic nerve damage in ocular hypertensive individuals.
• These ratios are independent of optic disc size and ocular magnification.
• Rim width ratios can be a supplementary tool in ophthalmoscopic evaluation but must account for overlap between normal and at-risk populations.