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.