Abstract
Purpose :
Van Herick assessment (VHA) of the anterior chamber angle is commonly used for angle closure screening, though its real-world accuracy is unclear. This study measures VHA test characteristics by ophthalmic technicians, ophthalmology residents, and glaucoma specialist attendings for identifying angle closure compared to a gold-standard attending gonioscopy.
Methods :
Patients ≥50 years old with no prior ocular surgery or laser iridotomy seen in a resident glaucoma referral clinic underwent unilateral VHA by 1 of 11 trained ophthalmic technicians, followed by VHA and Goldmann lens gonioscopy by 1 of 16 residents and 1 of 2 attendings. VHA preceded gonioscopy. Observers were masked to others’ grading. VHA was graded as open (peripheral anterior chamber depth ≥¼ corneal thickness) or closed; gonioscopy was graded as open (≥180° visible trabecular meshwork) or closed. Cohen’s kappa (κ) assessed VHA agreement between observers. VHA sensitivity and specificity for identifying gonioscopic angle closure were calculated, and the phi correlation coefficient (φ) was determined for each comparison.
Results :
131 subjects were 62.0±8.7 (mean±SD) years old, 56% were male, and 84% were African American. Angles were gonioscopically closed in 14.5% of 131 analyzed eyes (one chosen at random per subject when both eyes met inclusion criteria). Moderate agreement was observed when comparing technician or resident VHA to attending VHA, κ=0.48 and 0.56, respectively. Very good agreement was observed between resident and attending gonioscopy, κ=0.94. Sensitivity of technician, resident, and attending VHA for detecting angle closure was 57.9% (95% CI: 34.0-78.9%), 78.9% (53.9-93.0%), and 68.4% (43.5-86.4%), respectively. Specificities were 88.5% (80.3-93.6%), 88.2% (80.2-93.3%), and 87.5% (79.6-92.8%), respectively. Correlations between technician, resident, and attending VHA compared to attending gonioscopy were moderate, φ=0.43, 0.58, and 0.49. p<0.001 for all κ and φ.
Conclusions :
Resident and glaucoma specialist gonioscopy interobserver agreement was excellent. VHA shows varying results across observers and, even when performed by experienced providers, misses a substantial proportion of angle closure while incorrectly identifying roughly 1 in 8 open-angle eyes as closed. Clinical assessment of anterior chamber angle configuration is best accomplished with gonioscopy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.