A Clinical study of Primary Open Angle Glaucoma in Hospital Patients
Primary Open Angle Glaucoma (P.O.A.G) is widely prevalent all over the world. It is usually asymptomatic until advanced stage where there may be either irreversible marked visual field loss or advanced optic nerve head damage or both. So, much emphasis is to be given in early diagnosis. The present study was therefore, conducted at OPD of our Institute to study the followings:
- Prevalence of P.O.A.G. and its relationships with age, sex, religion, dietary habits, educational and emotional status, heredity, geographical pattern and socio-economic status, anterior chamber depth and axial length of the eye ball.
- Its relationship with some systemic disorders (e.g. diabetes, Hypertension, Hyperthyroidism, cardiovascular disorders, corticosteroid therapy and refractive error).
Materials and Methods:
This study included thorough history taking, routine clinical examination and special investigation like gonioscopy, applanation tonometry, perimetry (by Goldmann perimeter and Automated Perimeter in a limited number of patients). The present study was conducted with the following criteria on 184 patients (368 eyes) of P.O.A.G out of 53,840 patients attending the O.P.D. of our Institute from August, 1995 to February, 1996.
- I.O.P 21 mm. of Hg. by applanation
- Anterior Chamber is open gonioscopically
- Glaucomatous changes of optic nerve head and peripapillary retina
- Glaucomatous change in the visual field
Besides open angle of anterior chamber, presence of at least two of the above mentioned criteria were considered for diagnosis. The patients having congenital glaucoma or patients attending glaucoma clinic irregularly, non – cooperative patients and patients with advanced lental changes were excluded in this study.
Results and Discussion
The prevalence of P.O.A.G. was found to be 0.34% in this study. It was found to be lower as compared to most of the studies (Tielsch et al, 1.7% Bhowmick 0.9% and Salmon et al, 1.5%). This could be due to the fact that the prevalence rate was calculated amongst all age groups in the present study in contrast to the other studies conducted in a specified age group. Most of the cases in the present study were found to be above 30 years of age. Nearly 67.94% were male and 33.06% were female. 42.4% cases came from rural areas and the rest i.e. 57.60% from urban area. Most of the cases (91.85%) belonged to lower and middle income group. About 55% of the cases were illiterate. Majority of the cases (83.70%) were non vegetarian reflecting the regional dietary habits of the population. In the present study, the majority of the patients were brought to O.P.D. with complaints of difficulty of vision (67.94%), headache (20%), eyeache (2.71%) and seeing halos (11.4%). Family history of P.O.A.G. was found in 18.47% of the cases in present series, which was lower than the reports of Uhm et al, (27%) but higher than that of Teikari (10.2%).
Risk Factors:
Corticosteroid intake history was seen in 15.76% of P.O.A.G. cases in this study. Diabetes mellitus was associated with 10.86% of cases, systemic hypertension was detected, in 12.05%, hypothyroidism in 5.97% and ischaemic heart disease was found in 1.08% and myopia was detected in 46.73% . The axial length of the eye ball was measured in thirty ( sixty eyes) patients. In the majority of cases (60%), the axial length was within normal range (22 to 23mm). The visual acuity of majority of eyes (41.58%) was 6/12 or better. Ten eyes (2.71%) under study developed absolute glaucoma. The IOP of 21 mm. of Hg. or more by applanation tonometry was seen in 68.20% of eyes. The I.O.P. of 21mm of Hg or less by applanation was fond in 31.80%. These values closely resemble the reports of Klein et al, (31.7%) and Smith (30%). Diurnal variation of I.O.P. was studied in 40 patients (80 eyes).
The variation ranged from 1mm Hg. to 7mm. Hg Schiotz which was similar to values reported by other investigators. The cup: disc (C.D) ratio more than 0.5 was seen in 251 eyes (68.20%). The C.D asymmetry of more than 0.2 was found in 71 cases (38.59%). In this series, vertical diameter was taken into consideration and the C.D asymmetry therefore, was more important for Glaucomatous optic nerve head damage. Our observation was agreeable to the studies of Anderson et al, and Spousel. No obvious visual field defect was detected in 137 eyes (37.23%), Scotoma of different types was seen in 117 eyes (31.80%). Localized or generalized field constriction with or without scotoma was detected in 51 eyes (11.86%) No remarkable difference in visual field defect was found between Goldmann and automated perimetry in this study. Most of the eyes with cup: disc ratio more than 0.50, were associated with gross visual field defect. The greater the optic nerve head damage, the greater is the chance of visual field change.
References:
- Tielsch, J.M. et al, (1991: Racial variation in the prevalence of primary Open Angle Glaucoma: The Baltimore Eye Survey, J.A.M.A, 266 : 369.
- Bhowmick, A (1990): A study of prevalence of P.O.A.G, in O.P.D. patients. A dissertation submitted for M.S. Ophthalmology, to Calcutta University
