Abstract
Purpose:
To assess the potential role of Frequency Doubling Technology (FDT) perimetry in screening for glaucoma using data from the National Health and Nutrition Examination Survey (NHANES).
Methods:
The 6,797 participants aged 40 and older from 2005-2008 NHANES underwent ophthalmic evaluations including visual acuity, optic disc and macula photographs. Participants also underwent a 19-point supra-threshold screening test using the N-30-5 pattern on the Matrix FDT. An abnormal FDT was defined as any outcome that would result in the patient being referred on for further evaluation, including the test not being done, an abnormal result, insufficient data, or an unreliable test. The optic disc photos of 5,746 subjects were graded by a reading center. Macular diseases were determined based on the disc photos by the reading center. All 548 participants with cup-disc-ratio (CDR) ≥ 0.6 in either eye, and a random sample of 180 participants with CDR < 0.6 in both eyes were re-graded by glaucoma specialists. Participants were classified as having glaucoma if the consensus grading for glaucoma was “Probable” or “Definite” in either eye. We estimated the test properties of the FDT in screening for glaucoma, and in identifying potential causes of visual field loss, including glaucoma, macular disease, and/or visual acuity worse than 20/40.
Results:
Using the expert consensus of glaucoma as the gold standard, the sensitivity and specificity for FDT were 55% (95% CI: 48-61%) and 77% (95% CI: 76-78%) in the overall population. The sensitivity and specificity were 33% and 77% among participants with CDR < 0.6 in both eyes, and 66% and 70% among participants with CDR ≥ 0.6 in either eye. For the identification of glaucoma, macular disease, and/or visual acuity worse than 20/40, the sensitivity and specificity were 80% (95% CI: 77 - 83%) and 83% (95% CI: 82-84%) in the overall population. This represented the best diagnostic property for FDT, as the diagnoses of macular disease and decreased visual acuity were conditioned on abnormal FDT result.
Conclusions:
FDT perimetry lacks both sensitivity and specificity as a means of screening for glaucoma, retinal disease or decreased acuity in a population-based setting. Given no single test of glaucoma has yet been shown to be appropriate in a screening setting, investigators should consider novel approaches.