Content area
Full text
Introduction
After cataracts, glaucoma is the most common ophthalmic disease mentioned in the literature leading to irreversible blindness and is considered an important public health problem across the globe.1-3 With a global prevalence of 2.20%, about 57.50 million world's population is suffering from primary open angle glaucoma (POAG). In Europe, 7.8 million people are affected by POAG with a cumulative prevalence of 2.51%. POAG is more prevalent in the United Kingdom, affecting 2% of adults over 40 years of age and 10% of adults over the age of 75 years.3 Glaucoma particularly the POAG is a disorder of progressive neurodegeneration 4 of retinal ganglion cells (RGCs) and retinal nerve fiber layers (RNFL)3 resulting in poor quality of life, visual impairment, and blindness. Glaucoma can lead to certain structural changes in the optic nerve head (ONH) and RNFL along with progressive loss of visual fields. This functional and structural damage is highly variable among all glaucoma patients.
It is also important to detect this glaucomatous damage to avoid serious visual impairment and initiate appropriate treatment.5
Conventional automated visual field (VF) analysis is routinely used in glaucoma evaluation and its progression. Now a days ONH and RNFL imaging by optical coherence tomography (OCT) are getting popular to evaluate anatomical changes in glaucoma patients.5,6 OCT is a reliable, convenient imaging tool for the diagnosis and monitoring of retinal disorders. By utilizing infrared light,7 OCT provides us a tomographical three dimensional (3-D) study with quantitative and repeatable measures of the optic nerve head (ONH), macular, and RNFL parameters. Reversal of ONH and RNFL glaucomatous damage after intraocular pressure (IOP) lowering treatments has been reported in primary congenital glaucoma and infantile glaucoma in children and primary open angle glaucoma (POAG) in adults.8 Analyses of ONH/RNFL and confocal scanning laser ophthalmoscopy (CSLO) on experimental models and humans showed reversal of ONH and RNFL parameters after IOP reduction by medical or surgical treatment.8,9
Changes in the neuro retinal rim area and the cup volume of the optic disc are also documented by stereoscopic disc photographs.7 The effects of IOP reduction on peripapillary RNFL is conflicting and still not clear. Earlier studies showed increased RNFLT after trabeculectomy surgery10 but certain later studies mentioned no change in the thickness of RNFL after IOP lowering...