Glaucoma is usually categorized as open- or closed-angle glaucoma, and then subdivided into primary or secondary open- or closed-angle glaucoma. Most people with glaucoma have the type known as chronic open-angle glaucoma, which demonstrates virtually no detectable symptoms early on.
In fact, most types of glaucoma don't have any symptoms, so you would not expect to be aware of any eye problems, however, some more unusual types of glaucoma, which begin with rapid high elevation of intraocular pressure, are associated with eye pain or headache, blurred vision with the appearance of colored halos around lights, or occasionally, redness of the whites of the eyes.
Seeing an ophthalmologist or optometrist for regular eye checkups plays a very important role in catching glaucoma early on. The earlier glaucoma is detected, the earlier it can be treated and the less damage it will cause to your optic nerve fibres. Hence, a debilitating loss of vision can be avoided.
What your ophthalmologist needs to know from you
Your ophthalmologist or optometrist will need to obtain a detailed medical history of your eyes, as well as your general health. For example, your ophthalmologist or optometrist will need know if you have diabetes mellitus (sugar diabetes), systemic hypertension (high blood pressure), thyroid disease, heart disease, stroke, migraine, and other related disorders and if you have a family history of glaucoma. Although these factors do have a bearing on the diagnosis of glaucoma, the level of intraocular pressures has no relationship to the systemic blood pressure or tear circulation, which are completely different and independent systems.
Your ophthalmologist or optometrist will also need to know what medications you are taking because drugs such as cortisone or prednisone (among others) can cause an elevation in the intraocular pressures.
Your ophthalmologist or optometrist may perform a number of different eye tests to determine what, if any, is the existing state of damage to the nerve fibres in your optic disc. These tests include measuring your intraocular pressures (tonometry), the shape and colour of the optic nerve (ophthalmoscopy), visual field test (perimetry), the thickness of the cornea (pachymetry) as well as measuring the outflow angle of the eye lens (gonioscopy).
If a loss of peripheral vision is detected, your ophthalmologist or optometrist will examine your optic nerve discs for signs of physical damage. Normally the optic disc is flat, but if the intraocular pressure is elevated there will be an indentation in the disc, making it look like a cup. This is appropriately called "cupping". Your doctor will use an ophthalmoscope to assess the optic nerve for cupping, as well as the retina for any defects in the nerve fibre layer.
In later stages of glaucoma some symptoms may be present, such as:
- loss of side vision (peripheral vision)
- difficulty focusing on close work
- seeing coloured rings or halos around lights
- headaches and eye pain
- frequent changes of prescription glasses
- difficulty adjusting eyes to the dark
If you have any of these symptoms, see your ophthalmologist.
Frederick S. Mikelberg, MD
in association with the MediResource Clinical Team