Relation Between Acknowledged Glaucoma Risk Factors and Abnormal FDT Field Tests in Population–Based Glaucoma Screening

Abstract

Abstract: : Purpose: To evaluate whether there is a correlation between a patient’s response to a glaucoma risk factor questionnaire and the likelihood of an abnormal frequency doubling technology (FDT) visual field test. Methods: 515 participants from 20 community health fairs in Brooklyn, New York participated in our glaucoma screening project. Volunteers filled out a questionnaire that included six questions assessing various glaucoma risk factors. We asked participants if they had diabetes mellitus and/or hypertension, a family history of glaucoma, a previous eye injury or surgery, a change in vision within the last year, age over 45, and are they of African decent. Participants with a positive response to less than four risk factors were considered part of the low risk group, whereas those with four or more were considered high risk. The participants also underwent either a C20–1 or N30–1 FDT. FDT has been shown to be highly sensitive and specific in detecting visual field loss in glaucoma. A positive or abnormal perimetry test was defined as greater than one missed location on the FDT. Results: 16% of the participants took the C20–1 version of FDTs, while 84% took the N 30–1 version. Using the Fisher’s exact test comparing the abnormal versus normal results, there was no statistically significant difference between the two FDT versions (p value = 1.000). Of the 466 participants that answered the questionnaire and performed the FDT test, 301 were assigned to the low risk group and 165 to the high risk group. Participants that qualified for the high risk group had a 46% chance of obtaining a positive FDT result, as compared to a 32% chance for low risk participants. Using the Pearson Chi–Square test, the relation between a high number of risk factors and an abnormal FDT was statistically significant at a p–value of 0.003. Furthermore, participants of the high risk group had 1.8 times the odds of having an abnormal FDT compared to participants of the low risk group (odds ratio 1.82, 95% CI 1.23–2.68, p value 0.003). Conclusions: A positive response to four or more of these six risk factors is a predictor of an abnormal FDT. In settings where glaucoma diagnostic equipment is not available, these factors may be able to predict those who would have a positive FDT.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: systems/equipment/techniques • visual fields