Angle Recession Glaucoma (cont.)
Angle Recession Glaucoma Diagnosis
Ideally, angle recession should be discovered before glaucoma develops, so that the actual risk of glaucoma can be assessed and appropriate care can be arranged. In determining whether or not
a person has angle recession, the ophthalmologist performs different tests during an office examination. Each test is described below.
- Angle recession is always diagnosed by a test called gonioscopy.
- During gonioscopy, the drainage angle of the eye is checked. The angle of the eye is formed where the iris and the cornea
come together inside the eye. This test is important to determine if the angles are open, narrowed, or closed and to rule out any other conditions that could cause elevated IOP. To view the angle, a special contact lens is placed on the eye.
- During this test, the ophthalmologist examines the angle for characteristic
features of angle recession. The eye doctor also compares the affected angle
with the angle of the fellow eye. When many years have passed following the
injury, recognizing angle recession may be difficult, and only comparison
between the two angles on gonioscopy will show an abnormaility.
- If the eye is severely traumatized and gonioscopy cannot be performed, then a high-frequency ultrasound biomicroscopy may be used to examine the angles for any abnormalities.
- Visual field
testing is very important in detecting and monitoring optic nerve function,
which may be compromised in angle recession glaucoma. Visual field testing
checks the peripheral (or side) vision, usually with an automated visual field machine. This test is done to rule out any visual field defects due to glaucoma.
- Visual field defects may not become apparent until over 40% of the optic nerve fibers have been lost.
- Visual field testing may need to be repeated. If there is a low risk of glaucomatous damage, then the test may be performed only once a year. If there is a high risk of glaucomatous damage, then the test may be performed as frequently as every
- If the visual field defects seem to appear or change in a manner that is
uncharacteristic of glaucoma, then the ophthalmologist performs additional tests to look for other causes of vision loss.
- Tonometry is a method used to measure the pressure inside the eye.
- Elevated intraocular pressure (IOP) in one eye is a hallmark finding in angle recession glaucoma, but it may not be noted early on. High IOP that occurs soon after the injury (within the first few months) may indicate more extensive damage and, thus, a poorer prognosis.
- Measurements are taken for both eyes on at least two to three occasions.
Because IOP varies from hour to hour in any individual, measurements may be
taken at different times of day (for example, morning and night). A difference in pressure between the
two eyes of 3 mm Hg or more may suggest glaucoma.
- As in other forms of glaucoma, uncontrolled and sustained IOP elevation in angle recession glaucoma ultimately leads to optic nerve damage and vision loss.
- Each optic nerve is examined for any damage or abnormalities; this may require dilation of the pupils to ensure an adequate examination of the optic nerves.
- Different imaging studies may be conducted to document the status of the optic nerve and to detect changes over time.
photographs, which are pictures of the optic disc
(the front surface of the optic nerve), are sometimes taken for future reference and comparison.
- The front of the eyes (or anterior segment), which includes
the cornea, anterior chamber, iris, and lens, are examined using a slit lamp. A number of abnormalities in the anterior segment often accompany angle recession.
- Abnormalities in the posterior segment may signify prior episodes of trauma, which might have caused the angle recession. The posterior segment is considered to include the choroid, the retina, the optic nerve, and the vitreous humor (a gel-like substance in the eye that, along with aqueous humor, helps to retain eye pressure).
- Visual acuity,
which refers to how well one can see an object when one looks at it, is also
evaluated. An ophthalmologist determines visual acuity by having the patient read letters from across a room using an eye chart. Any changes in
central visual acuity are not typically seen until the late stages of glaucoma.
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