Improved retinal function after trabeculectomy in glaucoma patients.

PURPOSE: To investigate retinal function after reduction of intraocular pressure (IOP) by filtration surgery in patients with medically uncontrolled glaucoma. METHODS: Eleven patients (11 eyes) with medically uncontrolled glaucoma underwent trabeculectomy. Clinical investigation, visual field (testing with standard automated perimetry (SAP-Humphrey), optical coherence tomography (OCT), full-field electroretinography (full-field ERG) and multifocal electroretinography (mfERG) were performed preoperatively as well as 2 and 6 months after surgery. DESIGN: Interventional prospective, consecutive case series. RESULTS: No significant reduction was seen in mean log MAR visual acuity 2 or 6 months after filtration surgery. The mean preoperative intraocular pressure of 27.1 (+/-6.2) mmHg decreased to 19.0(+/-6.1) mmHg 2 months after surgery and to 17.1 (+/- 3.4) mmHg 6 months after surgery (both p = 0.001). The reduction in IOP significantly decreased the number of anti-glaucoma agents used, from 3.7 +/- 1.6 at baseline to 0.8 +/- 0.9 2 months after surgery and to 1.3 +/- 1.2 6 months after surgery (p = 0.004 and p = 0.008 respectively). The results of SAP, OCT and full-field ERG did not show any significant difference between pre- and postoperative values at any point in time. No significant improvement was found with regard to the first positive peak (P(1)) amplitudes in the macular retina (area 1) or in the perimacular retina/periphery (area 2) when measured with mfERG 2 months after surgery. The mfERG examinations revealed significantly improved P(1) amplitudes 6 months after surgery in both area 1 and area 2, compared with the preoperative values (p = 0.042 and p = 0.014 respectively). The implicit time of P(1) decreased significantly 6 months after surgery in area 2 compared with the preoperative values (p = 0.023). CONCLUSION: A significant lowering of IOP seems to improve the function of the central retina, as demonstrated by increased amplitudes and reduced implicit times assessed with mfERG.