Racial Differences in the Diagnostic Value of IOP Asymmetry

Abstract

 

Purpose

 

We have previously demonstrated that there is a direct relationship between the amount of intraocular pressure (IOP) asymmetry and the probability of having glaucoma. The purpose of the present study is to determine if this relationship varies by race.

 

Methods

 

Collaborative retrospective study of 375 glaucoma patients and 375 controls matched for age, race and gender. The study group was composed of equal numbers of Asian, Black, European, Latino and North African patients. Former Wills Eye Hospital fellows collected single pre-treatment measurements of IOP on patients diagnosed as having definite glaucoma based on characteristic optic nerve damage and confirmatory visual field damage. Patients with a normal eye examination who had normal-appearing optic discs and no apparent glaucoma, or who had a normal eye examination in association with refractive error or cataract, were used as controls. A logistic regression analysis that jointly modeled all race groups was used to determine if the relationship between IOP asymmetry and glaucoma differed by race.

 

Results

 

IOP asymmetry was significantly associated with glaucoma status overall and in each race group (p<0.001). The probability of having glaucoma at a particular value of IOP asymmetry differed significantly by race (p = 0.012). These probabilities were noticeably higher for Blacks and Latinos and noticeably lower for Asians. AUC values were similar across race groups and ranged from 0.69 for Asians to 0.83 for Blacks, Europeans and Latinos. The sensitivity and specificity of an optimal cut point of IOP asymmetry in predicting glaucoma status was also calculated for each racial group (Table 1).

 

Conclusions

 

There is a direct relationship between the amount of IOP asymmetry and the probability of having glaucoma. The strength of this relationship varies by race. An IOP difference of 2 mmHg or more between the fellow eyes is a moderately specific indicator for glaucoma in Blacks, Europeans, and Latinos.

 

 

Keywords: 463 clinical (human) or epidemiologic studies: prevalence/incidence • 464 clinical (human) or epidemiologic studies: risk factor assessment