Asian-specific vertical cup-to-disc ratio cut-off for glaucoma screening: An evidence-based recommendation from a multi-ethnic Asian population

Importance: Evidence-based guidelines are essential for glaucoma screening to work effectively.

Background: To derive a vertical cup-to-disc ratio (VCDR) cut-off for glaucoma screening in a multi-ethnic Asian population.

Design: The Singapore Epidemiology of Eye Diseases (SEED) study is a population-based study conducted from 2004 to 2011 in a single tertiary care research institute.

Participants: SEED comprised of 10 033 Chinese, Malay and Indian adults aged ≥40 (response rate 75.6%). After excluding participants with a history of glaucoma medication or surgery, 9673 participants were included for analysis.

Methods: A systematic eye examination, which included applanation tonometry, visual field testing, gonioscopy and dilated fundus examination was conducted.

Main outcome measure: Diagnosis of glaucoma.

Results: The distribution of VCDR and VCDR asymmetry were relatively homogenous in this multi-ethnic Asian population, with a 97.5th percentile value of 0.67 and 0.17, respectively. In the absence of more definite signs of glaucoma, VCDR ≥0.60 and VCDR asymmetry ≥0.20 provided the best balance between sensitivity (95.1%) and specificity (90.9%) in detecting glaucoma. For larger optic disc (≥2.0 mm), VCDR ≥0.65 with VCDR asymmetry ≥0.20 provided the best balance between sensitivity (84.8%) and specificity (93.2%).

Conclusion and relevance: Overall, VCDR ≥0.60 with VCDR ≥0.20 asymmetry provides a good balance between sensitivity and specificity in detecting glaucoma. For larger optic disc, VCDR ≥0.65 should be considered instead to mitigate against false-referrals due to larger physiological disc cupping. Our findings may act as a reference to populations with similar VCDR distribution.