Short time Intraocular pressure reduction effect on visual function in trabeculectomized open angle glaucoma patients

Abstract

Glaucoma disease is progressive optic nerve and retinal ganglion cell damage with subsequent visual field loss due to heterogeneous pathological process such as intraocular pressure, for IOP controling Trabeculectomy is the common surgical technique in many types of glaucoma. Retinal ganglion cells responsible for normal visual function. New researches about reversible phase of functional disturbance before cell death prompted us to investigate in this study the effects of Short time Intraocular pressure reduction on visual function in trabeculectomized open angle glaucoma patients. Methods and materials: This prospective case-control study included forty six open angle glaucoma patients who are visited in Nikookary eye clinic and candidate for Trabeculectomy surgery and they qualified by inclusion and exclusion criteria of this study. All patients underwent slit lamp ocular examination, gonioscopy and fundoscopy before and 3 month after Trabeculectomy. Refractive error (RE) and spherical equivalent (SE) was determined, then Best corrected visual acuity (BCVA) obtained by tumbling 6 meters E-chart and converted to logMAR. IOP checked in all patients with the same Goldmann applanation tonometer. Patients contrast sensitivity measured by Vector Vision contrast sensitivity chart CVS-1000 HGT, Humphrey system visual field analysis recognized their field defect, Macular and Retinal ganglion cell function observed by the P-ERG. Results: 46 patients include 35 male and 11 female, Patients age was 57 years averagely. Mean IOP reduction respect to baseline IOP was 58%. BCVA changes was not significant, while spherical equivalent showed significant myopic shift approximately 0.5 diopter and both visual field parameters meaningfully decreased. Contrast sensitivity level of 3, 6, 12, 18 cycle per degree of spatial frequency were developed too and P-ERG reports analysis represented only N95 implicit time statistically decrease after surgery. There was very strong correlation of spherical equivalent (SE), mean deviation (MD) and Pattern standard deviation (PSD). Strong correlation observed in 3- monthly change of best corrected visual acuity (BCVA) and N95 amplitude (P50-N95). But there was moderate to weak relationship before and after Trabeculoplasty in contrast level shift and implicit time of N95 variatuion.