Glaucoma Diagnosis

Diagnosis of glaucoma is difficult based on symptoms alone. Usually the condition is diagnosed in early stages by regular screening. This is because glaucoma takes a slow course and if detected late may have already damaged the vision to a large extent. It is therefore important to have regular eye tests and screening so that problems can be detected and treated as early as possible.

Eye screening tests are recommended every two years or more frequently if there is presence of other risk factors. Common risk factors include age, ethnicity, family history of glaucoma, diabetes and other eye diseases.

Eye tests for glaucoma

There are several glaucoma tests that can help detect the intraocular pressure and the extent of damage. The tests should be carried out during the same appointment to ensure results are as accurate as possible. These tests include:-

Tonometry or test for intraocular pressure

This uses an instrument called a tonometer to measure the intraocular pressure. Before the test a small amount of local anesthetic is sprayed or applied over the cornea. Thereafter a dye is placed onto the cornea. A blue light from the head of the tonometer is held against the eye to measure the intraocular pressure. Tonometry can diagnose ocular hypertension as well. Normal readings are between about 10 mmHg and 21 mmHg. There are various tonometers available but the most frequently used in a hospital setting is Goldmann's applanation tonometer.

Measurement of the central corneal thickness

The thickness of the central part of the cornea is measured as this gives an idea of the damage caused by the raised intraocular pressure.

Gonioscopy

This is an examination of the angle from where the aqueous humor drains. The angle is formed between the cornea and the iris. A gonioscopy can help to determine whether this angle is open or closed (blocked).

Visual field test (perimetry)

This is a computerized test that checks for loss of vision field or peripheral visual fields due to glaucoma. The individual is placed before the instrument and shown a sequence of light spots and asked which ones they can see. These spots are placed randomly all over the field of vision. Those in the periphery may not be visible to individuals who have damage to their visual field due to glaucoma.

Assessment of the retina and optic nerve

The optometrist first uses eye drops to dilate the pupils. Then the back of the yes or the retina is examined using a slit lamp (a microscope with a very bright light). This can show optic nerve damage. The optic disc is visulaized. Optic disc damage is assessed by looking at the vertical ratio of the pale centre (cup) to the overall size of the disc. A small cup and a thick rim (the darker edge surrounding the cup) may give a ratio of 0.3 or less (normal). A small number of people have a cup:disc ratio up to 0.7 but anything over that may indicate a pathology.

Further Reading

Last Updated: Jun 21, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2023, June 21). Glaucoma Diagnosis. News-Medical. Retrieved on October 31, 2024 from https://www.news-medical.net/health/Glaucoma-Diagnosis.aspx.

  • MLA

    Mandal, Ananya. "Glaucoma Diagnosis". News-Medical. 31 October 2024. <https://www.news-medical.net/health/Glaucoma-Diagnosis.aspx>.

  • Chicago

    Mandal, Ananya. "Glaucoma Diagnosis". News-Medical. https://www.news-medical.net/health/Glaucoma-Diagnosis.aspx. (accessed October 31, 2024).

  • Harvard

    Mandal, Ananya. 2023. Glaucoma Diagnosis. News-Medical, viewed 31 October 2024, https://www.news-medical.net/health/Glaucoma-Diagnosis.aspx.

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Does your ADHD medication increase your risk of glaucoma?