Key Points
- A prospective hospital-based study looked at patients, over the age of 40, who were identified as having open angle glaucoma
to ascertain whether diabetes is related to increased susceptibility to glaucoma. It was found that in the diabetic population
with OAG, the optic nerve damage occurs at a lower intraocular pressure in comparison to the OAG population without diabetes.
Screening of all diabetics is seen as a desirable tool for detecting open angle glaucoma.
Figure 1
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The World Health Organization (WHO) estimates that 12.8% of India's 8.9 million blind are blind due to glaucoma. We therefore
conducted our prospective observational study in the Department of Ophthalmology at Kasturba Hospital, MGIMS, Sewagram, India,
and as study subjects we included all patients older than forty years who were attending the eye department, including patients
receiving treatment for diabetes, and screened them for open angle glaucoma (OAG).
Our clinical examination included measurement of refraction and intraocular pressure (IOP), gonioscopy and disc assessment.
Those who were suspected or diagnosed glaucomatous were admitted as inpatients for further 24-hour phasing of IOPs. Automated
visual field1 24-2 along with optic disc assessment with photograph by a fundus camera were also carried out. Following these examinations,
patients with a definitive diagnosis of OAG were included in the study. Patients were excluded if the media remained hazy,
with non-visualization of the disc or if the patient was not co-operative with the visual field parameters.
Figure 2
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A total of 5385 patients were screened, of which 118 patients were identified as having OAG. We collected data for a period
of 12 months and analysed them with EPI 6 WHO epidemiology software.
What we found
The male:female ratio of the total sample size was 5937:5550 (male, 51.7%; female, 48.3%). Of the primary open angle glaucoma
(POAG) patients with refractive error, 30.4% were seen to have myopia in the right eye and 32.1% in the left eye; 35% recorded
hypermetropia in the right eye and 33% in the left eye. The degree of hypermetropia was usually in the lower range. Myopia
appears to have a correlation to OAG, which was present in 4.2% of eyes with low myopia and 4.4% of eyes with moderate-to-high
myopia, compared with 1.5% of eyes without myopia.
Table 1: Mean presenting intraocular pressure in OAG patients (applanation).
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The mean IOP was observed to be higher in OAG patients compared with the general population; mean IOP also increased with
increasing age. In the 40–49 age group, mean IOP in the right eye was 20.41 mmHg (with a standard deviation of 7.22 mmHg);
this increased to 22.83 mmHg (standard deviation (SD): 11.49 mmHg) in those aged seventy and over. The increase was significant
in the left eye: in the 40–49 age group, mean IOP was 21.16 mmHg (SD: 8.72 mmHg), which increased to 25.57 mmHg (SD: 10.44
mmHg) among those aged 70 years and over (Table 1).
