Glaucoma (cont.)

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What are glaucoma symptoms and signs?

Patients with open-angle glaucoma and chronic angle-closure glaucoma in general have no symptoms early in the course of the disease. Visual field loss (side vision loss) is not a symptom until late in the course of the disease. Rarely patients with fluctuating levels of intra-ocular pressure may have haziness of vision and see haloes around lights, especially in the morning.

On the other hand, the symptoms of acute angle-closure are often extremely dramatic with the rapid onset of severe eye pain, headache, nausea and vomiting, and visual blurring. Occasionally, the nausea and vomiting exceed the ocular symptoms to the extent that an ocular cause is not contemplated.

The eyes of patients with open-angle glaucoma or chronic angle-closure glaucoma may appear normal in the mirror or to family or friends. Some patients get slightly red eyes from the chronic use of eyedrops. The ophthalmologist, on examining the patient, may find elevated intraocular pressure, optic-nerve abnormalities, or visual field loss in addition to other less common signs.

The eyes of patients with acute angle-closure glaucoma will appear red, and the pupil of the eye may be large and nonreactive to light. The cornea may appear cloudy to the naked eye. The ophthalmologist will typically find decreased visual acuity, corneal swelling, highly elevated intraocular pressure, and a closed drainage angle.

How is glaucoma diagnosed?

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An eye doctor (ophthalmologist) can usually detect those individuals who are at risk for glaucoma (because of, for example, a narrow drainage angle or increased intraocular pressure) before nerve damage occurs. The doctor also can diagnose patients who already have glaucoma by observing their nerve damage or visual field loss. The following tests, all of which are painless, may be part of this evaluation.

  • Tonometry determines the pressure in the eye by measuring the tone or firmness of its surface. Several types of tonometers are available for this test, the most common being the applanation tonometer. After the eye has been numbed with anesthetic eyedrops, the tonometer's sensor is placed against the front surface of the eye. The firmer the tone of the surface of the eye, the higher the pressure reading.
  • Pachymetry measures the thickness of the cornea. After the eye has been numbed with anesthetic eyedrops, the pachymeter tip is touched lightly to the front surface of the eye (cornea). Studies have shown that corneal thickness can affect the measurement of intraocular pressure. Thicker corneas may give falsely high eye pressure readings and thinner corneas may give falsely low pressure readings. Furthermore, thin corneas may be an additional risk factor for glaucoma. Once a doctor knows the thickness of a patient's cornea, he or she can more accurately interpret the patient's tonometry.
  • Gonioscopy is done by numbing the eye with anesthetic drops and placing a special type of contact lens with mirrors inside the eye. The mirrors enable the doctor to view the interior of the eye from different directions. The purpose of this test is to examine the drainage angle and drainage area of the eye. In this procedure, the doctor can determine whether the angle is open or narrow and find any other abnormalities within the angle area. As indicated earlier, individuals with narrow angles have an increased risk for a sudden closure of the angle, which can cause an acute angle-closure glaucomatous attack. Gonioscopy can also determine whether the eye is subject to chronic angle closure, whether blood vessels are abnormal, or whether hidden tumors might be blocking the drainage of the aqueous fluid out of the eye.
  • Ophthalmoscopy is an examination in which the doctor uses a handheld device to look directly through the pupil (the opening in the colored iris) into the eye. This procedure is done to examine the optic nerve (seen as the optic disc) at the back of the eye. Damage to the optic nerve, called cupping of the disc, can be detected in this way. Cupping, which is an indentation of the optic disc, can be caused by increased intraocular pressure. Additionally, a pale color of the nerve can suggest damage to the nerve from poor blood flow or increased intraocular pressure. Special cameras can be used to take photographs of the optic nerve to compare changes over time.
  • Visual field testing actually maps the visual fields to detect any early (or late) signs of glaucomatous damage to the optic nerve. In order to find and follow glaucoma, visual fields are measured by a computer one eye at a time. For this procedure, one eye is covered and the patient places his or her chin in a type of bowl. Lights of various intensity and size are projected randomly around the bowl. Then, when the patient sees a light, he or she pushes a button. This process produces a computerized map of the visual field, outlining the areas where the eye can or cannot see.
  • Optic nerve tomography and nerve fiber analysis create a three-dimensional image of the optic nerve to evaluate the nerve fiber layer and better evaluate optic nerve damage.

All of these tests are repeated at intervals of 1 to 4 times per year, depending on how well clinicians have controlled the disease, to assess the progress of the disease and the effect of the treatment.

Medically Reviewed by a Doctor on 12/3/2013

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