Predicting progression of glaucoma from rates of frequency doubling technology perimetry change.

PURPOSE

To evaluate the ability of longitudinal frequency doubling technology (FDT) to predict the development of glaucomatous visual field loss on standard automated perimetry (SAP) in glaucoma suspects.

DESIGN

Prospective, observational cohort study.

PARTICIPANTS

The study included 587 eyes of 367 patients with suspected glaucoma at baseline selected from the Diagnostic Innovations in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES). These eyes had an average of 6.7 ± 1.9 FDT tests during a mean follow-up time of 73.1 ± 28.0 months.

METHODS

Glaucoma suspects had intraocular pressure (IOP) >21 mmHg or an optic disc appearance suspicious of glaucoma. All patients had normal or nonrepeatable abnormal SAP at baseline. Humphrey Matrix FDT (Carl Zeiss Meditec, Inc, Dublin, CA) testing was performed within 6 months of SAP testing. The study end point was the development of 3 consecutive abnormal SAP test results. Joint longitudinal survival models were used to evaluate the ability of rates of FDT pattern standard deviation (PSD) change to predict the development of visual field loss on SAP, adjusting for confounding variables (baseline age, mean IOP, corneal thickness, and follow-up measurements of SAP PSD).

MAIN OUTCOME MEASURES

The R(2) index was used to evaluate and compare the predictive abilities of the model containing longitudinal FDT PSD data with the model containing only baseline data.

RESULTS

Sixty-three of 587 eyes (11%) developed SAP visual field loss during follow-up. The mean rate of FDT PSD change in eyes that developed SAP visual field loss was 0.07 dB/year versus 0.02 dB/year in those that did not (P < 0.001). Baseline FDT PSD and slopes of FDT PSD change were significantly predictive of progression, with hazard ratios of 1.11 per 0.1 dB higher (95% confidence interval [CI], 1.04-1.18; P = 0.002) and 4.40 per 0.1 dB/year faster (95% CI, 1.08-17.96; P = 0.04), respectively. The longitudinal model performed significantly better than the baseline model with an R(2) of 82% (95% CI, 74-89) versus 11% (95% CI, 2-24), respectively.

CONCLUSIONS

Rates of FDT PSD change were highly predictive of the development of SAP visual field loss in glaucoma suspects. This finding suggests that longitudinal FDT evaluation may be useful for risk stratification of patients with suspected glaucoma.