Optical coherence tomography measurement of nerve fiber layer thickness and the likelihood of a visual field defect.

Purpose

To determine if optical coherence tomography (OCT) measurements of nerve fiber layer (NFL) thickness can be used to predict the presence of visual field defects (VFD) associated with glaucoma.

Design

Quota-sampled, cross-sectional study.

Methods

Retrospective study of OCT NFL thickness measurements in 276 eyes of 276 subjects. All persons received OCT NFL thickness analysis; 136 eyes underwent frequency-doubling technology (FDT) perimetry; and 140 eyes underwent Swedish interactive threshold algorithm (SITA) perimetry. We defined a parameter called NFL(50), which is the NFL thickness value at which there was a 50% likelihood of a VFD with either SITA or FDT perimetry. We evaluated the use of NFL(50).

Results

The mean NFL thickness with (n = 68) and without (n = 68) a VFD in the FDT group was 93.2 microm +/- 22.6 and 108.4 microm +/- 14.1, respectively. The mean NFL thickness with (n = 70) and without (n = 70) a VFD in the SITA group was 78.9 microm +/- 24.8 and 103.0 microm +/- 18.0, respectively. The FDT mean NFL(50) value was 98.5 microm. The SITA mean NFL(50) value was 87.0 microm. The area under the receiver operator characteristic (AROC) curve for mean NFL was 0.73, and the positive predictive value (PPV) for FDT mean NFL(50) was 72.2%. For SITA mean NFL, the AROC was 0.79 and the PPV for NFL(50) was 77.2%.

Conclusion

Nerve fiber layer thickness analysis using OCT may be clinically useful in identifying subjects who have visual field loss. However, the PPV suggests that OCT may need higher resolution and better reproducibility to enhance its sensitivity and specificity for population screening.