Predicting visual field loss in ocular hypertensive patients using wavelet-fourier analysis of GDx scanning laser polarimetry.

PURPOSE

To predict which ocular hypertensive (OHT) patients later develop a visual field loss by applying shape-based analysis (wavelet-Fourier analysis, WFA) to retinal nerve fiber layer (RNFL) thickness estimates.

METHODS

Visual field information and scanning laser polarimetry (SLP) RNFL estimates were obtained from both eyes of 122 patients (73 glaucoma and 49 OHT) and 102 healthy individuals. WFA was applied to RNFL temporal, superior nasal, inferior, and temporal (TSNIT) curves (28 points) of the glaucoma and healthy eyes to obtain a classifier. Without modification, the classifier was then applied to the OHT eyes (16 OHTconverters and 33 OHTnonconverters). The visual fields of the OHT patients (6-month follow-up for a mean period of 4 years) were analyzed using the Advanced Glaucoma Intervention Study (AGIS) criteria to identify eyes which developed subsequent field loss in this period of time (OHT converters) and those that did not (OHT nonconverters). For the OHT converters, the classifier was applied to scans from each of three points in time before the initial visual field damage. For the OHT nonconverters, the last available scan was used. The accuracy of the WFA metric in predicting conversion of OHT eyes was assessed by calculating area under the receiver operating characteristic (ROC) curve (area under the ROC curve, AUC), sensitivity at 80% specificity, and likelihood ratio.

RESULTS

The performance (AUC) of WFA in predicting conversion of the OHT eyes from scans taken just before visual field loss was 0.83 with a sensitivity (SD)/specificity (SD) of 0.76 +/- 0.11/0.80 +/- 0.07 and likelihood ratio (+LR +/- SD) of 3.8 +/- 1.4. Performance for scans obtained 6 months before the first signs of visual field defects was 0.77 (AUC), 0.71 +/- 0.11/0.80 +/- 0.07 (sensitivity/specificity), and 3.5 +/- 1.4 (+LR +/- SD). Performance was 0.73 (AUC), 0.59 +/- 0.12/0.8 +/- 0.07 (sensitivity/specificity), and 3.0 +/- 0.12 (+LR +/- SD) using the earliest available RNFL estimates.

CONCLUSION

The WFA method of temporal, superior nasal, inferior, and temporal shape analysis offers a means of predicting progression in OHT patients before visual field loss.