Structural and functional assessment by hemispheric asymmetry testing of the macular region in preperimetric glaucoma

To investigate structural measurements of the macular area in preperimetric glaucoma (PG) patients using spectral domain optical coherence tomography with two functional measurements [10-2 Humphrey visual field (HFA) and 10-2 Microperimeter-1 (MP-1)] and by macular symmetry testing.

Fifteen eyes of 15 PG subjects with a retinal nerve fiber layer defect in the inferior hemisphere and 15 eyes of 15 normal control subjects were enrolled. Macular symmetry testing was performed between the superior and inferior zones by comparing zone thickness in each hemisphere. Perimetric sensitivity asymmetry was calculated with two functional measurements. Structure-function relationships between macular symmetry testing and the mean retinal sensitivity of the corresponding hemifield or perimetric sensitivity asymmetry were calculated using Spearman's rank correlation and linear regression.

Macular zone thickness in the abnormal hemispheres was significantly less than that in normal hemispheres in PG eyes and the corresponding hemispheres in control eyes (P < 0.001). Macular symmetry testing was significantly lower in PG eyes compared to control eyes (P < 0.001). HFA (10-2) and MP-1 (10-2) correlated significantly (rs = 0.81, P < 0.0001). Macular symmetry testing values were significantly correlated with perimetric sensitivity and perimetric sensitivity asymmetry with two functional measurements (rs = 0.61, P = 0.02; HFA and rs = 0.68, P = 0.006; MP-1).

Our results suggest that macular asymmetry analysis can reveal the structure-functional relationship in PG eyes.