Articles about Eye Health and Disease 2001
 

Incidence of Open Angle Glaucoma

(From MC Leske, MD et al. Incidence of Open-Angle Glaucoma. Arch Ophthalmol 2001;119:89-95.)

The Barbados Eye Study measured the prevalence and risk factors for major causes of visual loss among 4709 Barbadian-born citizens, aged 40 to 84 years (1988-1992). Individuals were randomly chosen for the study, which included a comprehensive eye examination, which was then repeated in four years. This study looked at the 4-year risk of developing open-angle glaucoma in a black population.

Glaucoma is a common cause of visual loss, especially among black individuals. In glaucoma, the optic nerve, which carries visual information to the brain from the eye, degenerates. Elevated eye pressure plays a major role in this deterioration, which is not reversible once it occurs. Over time, peripheral vision is lost, followed by the central vision. This occurs often without any eye symptoms at all.

In the study cited above, 3427 members of the Barbados Eye Study were examined 4 years after an initial examination to determine if there was evidence of glaucoma. Some individuals had been diagnosed with glaucoma during this interval. In those that had not been diagnosed, peripheral visual field testing, optic nerve evaluation, and intraocular pressure measurements were taken to determine if glaucoma had developed.

The results of the study, looking at a predominantly black population of people, were as follows:

• The 4 year risk of open angle glaucoma (the most common type of glaucoma) in black participants was 2.2%, based on 67 newly developed cases.

• The incidence of glaucoma ranged from 1.2% in the 40-49 year old age group, to 4.2% at ages 70 years or more.

• Of the newly developed cases, only half had been diagnosed prior to the 4 year study examination. The remainder were diagnosed at the time of the 4 year exam.

• Of the 67 new cases of glaucoma, only about half had abnormally high intraocular pressures at the baseline examination (over 21 mmHg). The remainder had pressures which fell within the normal range at the time of the examination.

• The risk for developing glaucoma was highest in those who were felt to be suspicious for having glaucoma at the baseline examination (26.1% risk of glaucoma).

The authors of the study state that especially important findings from the study are that glaucoma was considerably under detected in this population over the 4 year period, and that intraocular pressure was elevated in only about half of those going on to develop glaucoma.  Thus, a high suspicion for glaucoma must be maintained, especially those with additional risk factors for glaucoma.

 

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