Structure-function relationships in normal and glaucomatous eyes determined by time- and spectral-domain optical...

To compare the relationships between retinal mean sensitivity (MS) and retinal nerve fiber layer (RNFL) thickness, as measured by time-domain (TD) and spectral-domain (SD) optical coherence tomography (OCT).

Recruited subjects were divided into normal, glaucoma suspect, and glaucoma groups. RNFL thickness was measured with TD- and SD-OCT, and MS was assessed with visual field perimetry and expressed in decibels and 1/L, where L is luminance in lamberts. The relationship between SUPERIOR MS and INFERIOR RNFL thickness (clock-hour segments 5, 6, 7, and 8) and that between INFERIOR MS and SUPERIOR RNFL thickness (clock-hour segments 10, 11, 12, 1, 2, and 3) were correlated by linear and logarithmic regression analyses. Pearson's correlation coefficients (R), for both OCTs were compared by using Hotelling's t-test.

Ninety-five eyes of 76 subjects were prospectively included. Twenty-five eyes were classified as normal, 25 with glaucoma suspect, and 45 with glaucoma. In normal and glaucoma suspect eyes, there were no significant relationships between MS and RNFL thickness. In glaucomatous eyes, the associations between MS and RNFL thickness were R = 0.31 to 0.57 with TD-OCT and R = 0.47 to 0.66 with SD-OCT, and the correlation of SUPERIOR RNFL thickness with INFERIOR MS was significantly better with SD-OCT than with TD-OCT in both linear and logarithmic regression models.

The results showed that, in mild-to-moderate glaucoma, SD-OCT offers an improved structure-function correlation compared with TD-OCT, when applied to the detection of INFERIOR MS and SUPERIOR RNFL defects.