Abstract
Purpose: :
To investigate retinal function after lowering the intraocular pressure (IOP) as a result of filtration surgery in patients with medically uncontrolled glaucoma.
Methods: :
Eleven patients (11 eyes) with medically uncontrolled glaucoma underwent trabeculectomy. Clinical investigation, visual field (VF) testing with standard automated perimetry (SAP-Humphrey), optical coherence tomography (OCT), full-field electroretinography (ERG) and multifocal electroretinography (mfERG) were performed preoperatively as well as two and six months after surgery.
Results: :
There was no significant reduction in mean logMAR visual acuity neither two nor six months after filtration surgery (p=1.00 and p=0.197 respectively). The mean preoperative intraocular pressure of 27.1 (±6.2) mmHg decreased to 19.0(±6.1) mmHg at two months after surgery and to 17.1 (± 3.4) mmHg at six months after surgety (p=0.003 and p=0.003 respectively). The reduction in IOP resulted in a significantly decreased necessity for antiglaucoma agents from 3.7±1.6 at baseline to 0.8±0.9 at two months after surgery and to 1.3±1.2 at six months after surgery (p=0.007 and p=0.009 respectively). The results of SAP, OCT and ERG did not show any significant difference between pre- and postoperative values at any point of time. No significant improvement was found regarding P1 amplitudes in the fovea (area 1) nor in the periphery (area 2) assessed with mfERG at two months after surgery (p=0.594 and p=0.593 respectively). The mfERG recordings revealed significantly improved P1 amplitudes in the fovea as well as in the periphery at six months after surgery, compared to the preoperative values (p=0.041 and p=0.017 respectively). Likewise the implicit time of P1 decreased significantly in the periphery at both two and six months after surgery compared to the preoperative values (p=0.048 and p=0.019 respectively).
Conclusions: :
A significant lowering of IOP seems to cause improvement of function in the central retina demonstrated by increased amplitudes and a reduced implicit time assessed with mfERG.
Keywords: electrophysiology: clinical • optic nerve • retina: distal (photoreceptors, horizontal cells, bipolar cells)