Clinical evaluation of Glaucoma Suspect

Abstract

Primary open angle glaucoma, in its early stage is essentially symptomless, although sometimes patients with higher lOPs have non-descript symptoms such as vague eye ache. The initial symptom may present only at the later stages when extensive field loss develops or central vision is involved.

An important step in making an ealry diagnosis of POAG is being suspicious that it maybe present. The ophthalmologist needs to identity those patients in whom there are sufficient risk factors to raise suspicion that glaucoma may develop in the future (glaucoma suspect) or who may already have the condition in its early stages.

Individuals at greatest risk for glaucoma must be identified so that appropriate observation is instituted. These include persons with a family history of glaucoma, black race, myopia and diabetes in addition to those with ocular risk factors such as elevated intraocular pressure, suspicious appearing optic discs and visual field changes.

Damage from glaucoma can present in two ways. Classic focal or localized damage may occur with its well-recognized notch of the optic disc rim and corresponding visual field scotoma. However, in many patients the first change may be a diffuse loss of disc neural rim with a generalized constriction or diminished sensitivity of the visual field. This is often much more difficult to recognize. In these instances, psychophysical and electrophysiologic tests, such as contrast sensitivity, color vision, and pattern electroretinograms may be useful. Those tests measure macular functions, which may be affected by this diffuse process.

In caring for those patients at risk for the development of glaucoma (glaucoma suspects), it is of vital importance to document their baseline status, including intraocular pressure at different times of the day to overcome deceiving effect of wide diurnal variation. Threshold static permietry of the central 30 degrees and possibly the nasal periphery and the appearance of the optic nerve photographically should be done. It is then possible to compare the patient's status with the baseline findings to detect any change in the following follow-up visits.

Pooled data from large epidemiological studies indicate that the mean lOP is approximately 16 mmHg, with a standard deviation of3 mmHg. In the past, the value 2! mmHg was used to separate abnormal pressures from normals and to define which patients requires ocular hypotensive therapy. There is an agreement now that, for the population as a whole, no clear line exists between safe and unsafe lOP. lOP is currently seen as a very significant risk factor, but still the only risk factor that may currently be defined and manipulated.