Frequency-doubling perimetry in examination of open-angle glaucoma with hemifield defect

OBJECTIVE: To determine whether frequency-doubling perimetry (FDP) can find visual field defect of early glaucoma which can not be found by conventional perimetry. METHODS: Forty-nine eyes of 49 patients with open-angle glaucoma and hemifield defect detected by Humphery Field Analyzer (HFA) were tested by both FDP (threshold test C-20) and Heidelberg Retina Tomograph (HRT). For each hemifield, its FDP result was evaluated. According to the FDP results in intact HFA hemifields, the patients were divided into FDP normal group and FDP abnormal group. The HRT parameters of half disk corresponding to the intact HFA hemifields were compared between these two groups. RESULTS: There was a strong correlation between the mean sensitivity of FDP and mean deviation of HFA results (r = 0.58, P < 0.01). In intact HFA hemifields, 41% (20/49) of eyes showed visual loss in FDP tests, while in defective HFA hemifields, only 2% (1/49) of eyes was normal in FDP test. For the HRT parameters of half disk corresponding to the intact HFA hemifields, cup area and cup/disk area ratio were statistically bigger and rim area and rim volume were statistically smaller in FDP abnormal group than in FDP normal group. CONCLUSION: FDP is able to detect early glaucomatous visual field damage which can not be detected by HFA, but can be explained by the optic nerve glaucomatous changes in HRT parameters.