The effect of trabeculectomy surgery on the central visual field in patients with glaucoma using microperimetry and optical coherence tomography.

Purpose: To determine the functional and structural effects of trabeculectomy surgery on patients with advanced glaucoma and central visual field defects in the early post-operative period.

Methods: Thirty consecutive adult subjects with advanced glaucoma requiring trabeculectomy surgery and an established visual field defect within 10° of fixation underwent microperimetry (MAIA MP-1, CenterVue, Padova, Italy) and optic disc optical coherence tomography (OCT) imaging (Spectralis, Heidelberg Engineering, Germany) pre-operatively, and 1 month and 3 months following trabeculectomy surgery. Main outcome measures were post-trabeculectomy change in mean threshold on microperimetry and nerve fibre layer thickness on OCT. Fellow eyes were used as controls.

Results: The mean change in MP average threshold values from pre-operative to post-operative was 0.6 ± 1.9 dB for treated eyes and 0.1 ± 1.3 dB for control eyes (p = 0.14) at 1 month and 0.2 ± 2.3 and -0.3 ± 1.6 dB at 3 months (p = 0.22). Mean change in global nerve fibre layer thickness was -0.6 and -0.5 µm for operated and control eyes, respectively (p = 0.83), at 1 month and 0.8 and -0.4 µm at 3 months (p = 0.88). The kappa agreement for structure-function correlation between OCT and MP was 0.735 (confidence interval 0.59-0.88) (p < 0.005).

Conclusions: Central visual function and retinal nerve fibre layer thickness appear to be preserved in glaucoma patients with central visual field defects undergoing trabeculectomy surgery in the early post-operative period. These data may inform glaucoma surgeons considering trabeculectomy surgery in this patient group.