Comparitive study between normal tension glaucoma and primary open-angle glaucoma

Abstract

The study is conducted to determine the functional and structural differences between NTG and POAG, to assess the rate of conversion of NTG into POAG and its early intervention. It is a hospital based prospective, cross-sectional study of 56 NTG and 56 POAG patients. History was taken and comprehensive ophthalmic examination with glaucoma work up was done.Majority of the patients belonged to the age group between 51 and 60 years i.e. 48.2% in NTG and 62.5% in POAG. Majority of the NTG patients i.e. 33 (58.9%) were females while 41(73.2%) were males in POAG. 40% of NTG patients had systemic association like bronchial asthma, diabetes, hypertension, ischemic heart disease and migraine. There was no significant difference in CDR between two groups. Inferior & temporal neuroretinal rim thinning was more common in NTG. While bipolar thinning & superior rim thinning was more common in POAG. There is significantly more thinning of RNFL in POAG than NTG. The mean deviation (MD) & pattern standard deviation (PSD) in visual fields between NTG & POAG showed no significant difference. Whereas the field loss was near centre of fixation in NTG group compared to POAG which was diffuse. These differences between NTG and POAG suggest that the pathogenesis of NTG includes IOP and IOP independent risk factors, while IOP is the main risk factor in POAG. The parameters assessed determine the risk and progression of NTG to POAG.