By Alan S. Crandall, MD
This article in the June/July issue of the Journal of Glaucoma assessed the rate of clinically-significant angle closure in predominantly Caucasian hyperopes aged 40 and older. The authors found that clinically-significant angle closure may be more common in this population than previously thought. They therefore recommend that ophthalmologists include gonioscopy as part of routine ophthalmic examinations in hyperopic adults.
The value of this paper is twofold: It emphasizes that Caucasian patients who are hyperopic and aged 40 years and older are probably at higher risk for angle closure than previously believed, and that gonioscopy should be performed in this setting routinely and annually.
The study included 84 patients (84 eyes) aged 40 years and older with hyperopia of at least 1D who were consecutively recruited at a community ophthalmology clinic with a predominantly Caucasian population in central Israel. They underwent detailed darkroom gonioscopy.
Primary angle closure was diagnosed if there was iridotrabecular apposition greater than 180 degrees not secondary to an identifiable ocular disorder. Biometric parameters were measured and compared between eyes with and without angle closure.
Fourteen patients (16.7 percent) were diagnosed with angle closure. A statistically significant difference was observed between eyes with and without angle closure in mean axial length (22.07 ± 0.72 vs. 22.61 ± 0.97, P = 0.028), anterior chamber depth (ACD) (2.45 ± 0.33 vs. 2.89 ± 0.32, P < 0.001) and lens thickness (4.97 ± 0.3 vs. 4.62 ± 0.4, P = 0.002). Degree of hyperopia was marginally significant (3.13 ± 2.3 vs. 2.45 ±1 .5, P = 0.09).
Multivariate analysis found that only ACD remained statistically significantly different (P = 0.016). When the authors tested the ability of ACD to distinguish eyes with angle closure, the area under the receiver operating characteristic curve was 0.824. Using a cutoff ACD value of 2.65 mm, sensitivity was 0.786 with a specificity of 0.812.
They say that the prevalence of preglaucomatous angle closure, in absolute number and relative to angle-closure glaucoma, has not been investigated previously in Caucasian people. Their results suggest that if gonioscopy is not performed as part of a routine ophthalmic examination in a Caucasian hyperopic adult, there is a 1:6 chance that clinically-significant angle closure will be missed. They recommend standardization and inclusion in ophthalmic training of the technique and interpretation of gonioscopy.
The authors also conclude that for the purpose of population screening, where it may not be feasible to adequately perform gonioscopy, future studies should evaluate the diagnosis of angle closure using ACD combined with other demographic, refractive or biometric parameters.