Glaucoma Detection Lower in Patients With African Descent Than European Descent

Reference database-based criteria for glaucoma detection may under represent patients with African descent (AD), as a study published in the American Journal of Ophthalmology shows lower diagnostic performance of retinal nerve fiber layer thickness (RNFLT) and Bruch’s membrane opening minimum rim width (BMO-MRW) in these patients compared with those with European descent (ED). 

The study included 382 eyes of 255 glaucoma patients (ED=170, AD=85) and 94 eyes of 50 healthy individuals (ED=30, AD=20). Global and sectoral RNFLT and BMO-MRW were measured with optical coherence tomography (OCT). The researchers evaluated global measurement below the 5th or 1st percentile, 1 or more of the 6 sector measurements below the 5th or 1st percentile, and superotemporal (ST) and/or inferotemporal (IT) measurement below the 5th or 1st percentile. The researchers compared the sensitivities and specificities of these measurements for detection of glaucoma.

The study shows that the best performance for detection of glaucoma among RNFLT classifications with a sensitivity of 89.5% and specificity of 87.2% was seen in ST and/or IT RNFLT below the 5th percentile. Sensitivities of ST and IT RNFLT and BMO-MRW measurements below the 5th percentile criteria for AD individuals were lower than in ED individuals (RNFLT: 83.7% vs 92.5% and BMO-MRW: 72.1% vs 88.5%, respectively). 

Lower measurements for AD individuals than in ED individuals were also seen for specificities (AD RNFLT: 73.7% and BMO-MRW: 89.5% vs ED RNFLT: 96.4% and BMO-MRW: 98.2%, respectively). 

The researchers explain that the diagnostic performance of RNFLT and BMO-MRW measurements was consistently lower in AD individuals than in ED individuals, and warned that BMO-MRW criteria may not detect up to one third of eyes with glaucoma.

“Clinicians should be careful when using OCT with the current…reference database since RNFLT and especially, BMO-MRW criteria are not adequate for diagnosing glaucoma in AD individuals,” the researchers report.

Part of the reason for this may be because patients of AD may have greater optic disc areas, larger cup to disc ratios, and bigger BMO areas in general than individuals of ED. However, the reference databases largely consist of patients with ED. The researchers in this study relied on a newer age and optic disc size adjusted reference database that includes 246 White participants, 47 Hispanic participants, 47 Black participants, and 25 Asian participants. The researchers explain that this “may not be diverse enough to adequately represent the normal range of population variations in the RNFL and BMO-MRW measurements” in the United States.

“Although race specific reference databases are under development, it remains to be determined whether sensitivity and specificity will improve with their use, as there is considerable variability within racial and ethnic groups,” according to the researchers.

Study limitations include a relatively small sample size, possible confounding of the observed high sensitivities due to how glaucoma was defined, and the study’s exclusion of highly myopic eyes.

Disclosure: Multiple study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.