Purpose:
Glaucoma is characterized by progressive loss of retinal ganglion cells and corresponding visual field loss. Macular is an area for central vision and more than 50% of retinal ganglion cell is located in macular. To evaluate the point-wise relationship between localized visual field sensitivities, as measured with Standard Achromatic Perimetry (SAP), and the corresponding macular thickness maps, as measured with spectral-domain optical coherence tomography (SD-OCT)
Methods:
In a prospective cross sectional study, 60 glaucoma subjects (one eye per subject) recruited from an academic institution underwent SAP tests (Humphrey field analyzer, central 24-2 of SITA standard) and SD OCT scans (SPECTRALIS, posterior pole analysis). Retinal sensitivities of 16 central test points in SAP results were recorded. A corresponding 16 point map of the macular thickness was constructed by averaging 2x2 squares of the 64 points of the OCT read out. (see diagram). A linear regression analysis of the visual field sensitivities and the mean retinal thickness values was performed.
Results:
There was a significant correlation between the visual field sensitivities and the mean retinal thickness values of corresponding retinal regions (r = 0.350 to 0.627, all p < 0.006 in all eyes). The strongest correlation was found in the central 2 points located temporal to fovea (r = 0.602 and 0.627, p < 0.001). Superior and inferior temporal points showed relatively weaker correlation (r = 0.350 and 0.362, p < 0.006).
Conclusions:
There is a significant pointwise correlation between maular thickness, determined by SD OCT, and corresponding visual field threshold sensitivities. This result provided more accurate information regarding the topographic relationship between structural and functional glaucomatous damage. Our result suggests the possibility of topographic macular thickness measurement can be used as a structural assessment tool which may reflect regional early functional loss.