Abstract
Objective : To study and compare the visual field defects in subjects with newly detected primary open angle glaucoma and normotensive glaucoma using HUMPHREY FIELD ANALYSER 30-2 swedish interactive thresholding algorithm(SITA) standard technique and to establish specific visual field loss patterns in each group and establish varied pathomechanisms. Methods: A prospective study 37 eyes of 25 patients with normal tension glaucoma(NTG) and chronic simple glaucoma(CSG). Patients were subjected to visual field testing using HUMPHREY FIELD ANALYSER(HFA) 30-2, SITA(Swedish interactive thresholding algorithm) standard method. Results: There was significant preponderance of early visual field defects in patients with NTG in comparison to patients with CSG (64% compared to 32.4%). Strong statistical differences were found in number of patients with scotomas falling with 6 degrees of central fixation (p<_0.001) in NTG comparing with CSG. Conclusion : results suggest that field defects between chronic simple and normotensive glaucoma do not differ in most aspects except for those in NTG group being closer to fixation and should not be used to underline different pathomechanisms in the two groups.
Highlights
The modern understanding of glaucoma dates to the mid 19th century and the concepts have evolved over the last 100 years
The intra ocular pressure (IOP) in normal tension glaucoma (NTG) is lesser than that seen with primary open angle glaucoma(POAG) but tend to be higher than that recorded in normal individuals[2]. patients with NTG have wider diurnal fluctuations than general healthy population[2].IOP spikes that might be occurring during nights in these subjects should be kept in consideration which is missed in routine office hour testing[3]
A total of 74 eyes were studied. 37 eyes of 25 patients with NTG were compared with 37 eyes of 25 patients with chronic simple glaucoma (CSG)
Summary
The modern understanding of glaucoma dates to the mid 19th century and the concepts have evolved over the last 100 years. Today the entity refers to a diverse group of disorders that have different presenting symptoms, pathophysiology, clinical signs and treatment. They share a common end point in optic neuropathy resulting in its atrophy and corresponding visual field defects. Raised intra ocular pressure (IOP) is only the most significant risk factor while there is a clinical variant where optic neuropathy occurs and progresses at normal values of IOP. This variant which may have additional pathomechanisms and is termed as NTG earlier termed as low tension glaucoma[1]. The retinal nervefibre layer shows more localized defects, closer to macula in the NTG group[4]. 2.1 Visual field abnormalities
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