What Are the Screening Tests for Glaucoma?
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Glaucoma Screening - An Overview

Published on Oct 06, 2022 and last reviewed on Sep 19, 2023   -  5 min read


Screening for glaucoma is important after the age of 40 years as it is considered progressive in nature, damages the optic nerve, and causes vision loss.

What Is Glaucoma?

Glaucoma is a common eye disease that affects and damages the optic nerve. The optic nerve is responsible for sending images to the brain. Increased intraocular pressure is considered the reason for optic nerve damage. It is regarded as the second most common leading cause of impaired vision or blindness worldwide. Glaucoma is slow, progressive, chronic in nature, and one of the main causes of blindness in people aged above 60.

  • Open-angle glaucoma and closed-angle glaucoma are the two main types of glaucoma.

  • Open-angle glaucoma is one of the most common types of glaucoma in which the drainage canal of the eye becomes clogged over time, ultimately damaging the optic nerve.

  • Primary angle-closure or narrow-angle closure is the other type of glaucoma in which increased eye pressure is seen due to the closed angle between the iris and the cornea.

  • The other types of glaucoma are normal-tension glaucoma, pigmented glaucoma, secondary glaucoma, congenital glaucoma, exfoliative glaucoma, neovascular glaucoma and uveitic glaucoma, and traumatic glaucoma.

What Are Causes of Glaucoma?

Glaucoma mostly occurs due to elevation or increase in the intraocular pressure that leads to an inability to drain. The nerve that connects the eye to the brain is called the optic nerve, which gets damaged due to increased pressure.

  • Age: It is the most common factor of glaucoma, as older people are more likely to get affected as compared to younger people.

  • Ethnicity: It is the other consideration in which African, Caribbean, or Asian origin has more chances of getting glaucoma.

  • Family History: It plays a vital role as the individual may develop glaucoma if parents or siblings have the same condition throughout life.

  • Other Medical Conditions: Such as diabetes, long-sightedness, and short-sightedness, can make the older age group people prone to glaucoma.

What Are Symptoms of Glaucoma?

Symptoms of glaucoma:

  • Blurred vision.

  • Nausea and vomiting.

  • Severe headache.

  • Intense eye pain.

  • Redness of eyes.

  • Tunnel vision.

  • Upset stomach.

  • Halo around lights or rainbow-colored rings.

  • Dilated pupil.

  • Sudden onset of visual disturbance, often seen in low light.

  • Blindspot.

  • Clouding of the normally transparent cornea.

  • Squinting.

  • Tenderness around the eye.

What Are Risk Factors of Glaucoma?

  • People of African, American, Irish, Turkish, Russian, Japanese, Inuit, Hispanic, or Scandinavian descent origin are more likely to suffer from glaucoma.

  • Family history of glaucoma.

  • People suffering from diabetes, heart disease, and sickle cell anemia are prone to glaucoma.

  • People who have cornea thinner than the usual one.

  • Individuals with farsightedness and short-sightedness.

  • People aged over 40 years are most at risk of glaucoma.

What Are Screening Tests of Glaucoma?

Glaucoma screening is done with tests that observe the changes in pressure of the eye's fluid, changes in the optic nerve, and changes in visual fields. The aim of screening is to diagnose early glaucoma. One or a combination of tests is done for the diagnosis of glaucoma. The procedure is non-invasive, quick, and painless.

Glaucoma tests involve -

  • Angle Exam: Also known as the gonioscopy test, that shows the drainage system in relation to the angle where the cornea (clear outer layer of the eye ) meets the iris (colored part of the eye). In this test, the cornea is contacted with a special lens after numbing the eyes using eye drops. The angle is predicted whether it is open or closed from the lens. The drainage system is considered blocked or narrow if the angle is closed, which is indicative of glaucoma.

  • Dilated Eye Exam: Is used to dilate (open) the pupil using bright light into the back of the eyes that magnifies the retina and optic nerve. Retina, optic nerve, size, shape, blood vessel, and color can easily be investigated by this test. It is helpful in estimating any damage caused to the optic nerve that might result in glaucoma.

  • Corneal Thickness Measurement: Also known as pachymetry, measures the thickness of the cornea after numbing the eye with an eye drop and using a small probe to determine the risk of glaucoma.

  • Eye Pressure Test: Is also known as tonometry or applanation. This test is done by using a tiny instrument that touches the surface of the eye and flattens the cornea in order to measure eye pressure. Increased eye pressure that is greater than 22 mm Hg is indicative of glaucoma.

  • Visual Field Test: It is done to determine the severity of glaucoma. In this test, the patient is asked to cover one of his eyes and to look straight ahead at the object. Automated static perimetry can also be used, which requires looking into track lights and machines. The specific spot presence is seen at which the vision gets blurry or blank.

  • Optic Nerve Imaging: This is another test used to make a visual picture of the optic nerve and retina. The pupil is dilated, and then with the help of optical coherence tomography, the images of each layer of eye tissue are obtained. Findings of optic nerve imaging, such as buckling or swelling of the optic nerve or bumpy retina, are examined in this test.

How to Treat Glaucoma?

Medical treatment involves eyedrops such as prostaglandin derivatives - Latanoprost, Travoprost, and Latanoprostene; beta-blockers, for example, Timolol; alpha-adrenergic agonists, for example, Apraclonidine (Iopidine) and Brimonidine. Oral medication is used when eye drop alone is not effective in bringing the eye pressure down; carbonic anhydrase is usually prescribed. Surgery includes laser therapy, filtering surgery, drainage tubes, and minimally invasive glaucoma surgery (MIGS). Lifestyle should be modified by eating a healthy diet, exercising regularly, limiting the caffeine level, and sleeping with the head elevated.


Glaucoma is a medical condition that damages the optic nerve and can cause permanent blindness over the years. Timely treatment of glaucoma can only be done after the proper screening test. Increased community awareness of glaucoma and earlier detection of the disorder will result in a reduced number of glaucoma cases. A routine eye examination is important for protecting the eyes. Surgical intervention done in the early stage may reduce the risk of vision loss due to glaucoma. Management of glaucoma involves medical, laser, and surgical modalities.

Frequently Asked Questions


What Is Meant By Glaucoma Screening?

Glaucoma is an eye disorder that arises due to increased pressure build-up, and glaucoma screening is a group of tests available to detect the disease. Fluid accumulation in the front part of the eye and, thereby, an increase in eye pressure is known as glaucoma, which can eventually lead to damage of the optic nerve and loss of vision. Screening tests help identify the condition as early as possible, therefore preventing vision loss. There are several tests available. Glaucoma can be broadly classified as open-angle glaucoma and closed-angle glaucoma. Tests for glaucoma include tonometry, ophthalmoscopy, pachymetry, perimetry, and gonioscopy.


Who Should Undergo Screening For Glaucoma?

It is always advisable to start screening for glaucoma before the warning signs and especially if you are at risk. The risk factors for glaucoma include the following:
- A family history of glaucoma puts you at a higher risk of developing the condition.
- Glaucoma is more common in populations above the age of 60.
- Ethnicity: African American, Hispanic and Asian races are among the most affected by the disease, and it is the leading cause of blindness in the African American community.
- Health conditions like diabetes, heart disease, high blood presssure, etc.


What Is the Importance of Glaucoma Screening?

Glaucoma can lead to blindness, and the signs of glaucoma do not exhibit themselves until the disease has progressed significantly. Therefore it is imperative to do screening so that the disease can be detected at an early stage and thereby prevent or control significant damage.


What Is the Frequency of Glaucoma Screening?

The frequency of glaucoma screening depends on age and risk factors. Based on these factors, the doctor will advise the individual on the frequency of screening. But for a broad classification,
- Age 20-29: For individuals with a family history or presence of risk factors, screening can be done every three to five years.
- Age 30-39: For individuals with a family history or presence of risk factors, screening can be done every two to four years.
- Age between 40 to 64: requires screening every two to four years, irrespective of family history or risk factors.
- Age above 65 requires screening every one to two years.


What Is the Duration of Glaucoma Screening?

Glaucoma screening does not require a lot of time; depending on the type of test, it may take from a few seconds to five-ten minutes. The eyes may be dilated using eye drops; therefore, it may take a while for proper vision to be restored, but the test as such does not take much time.


Does Glaucoma Test Cause Pain?

Glaucoma tests are done externally and are non-invasive; therefore, they do not cause any pain. However, the eye drops that are used to dilate the pupils of the eyes may cause some stinginess and hazy vision, which is temporary.


Can a Patient Drive After a Glaucoma Test?

The eye drops used to dilate the pupil before the test may make the eyes hazy and vision blurry for a while or even up to several hours; therefore, it is not advisable to drive immediately after the test.


Is an Optometrist Qualified to Diagnose Glaucoma?

An optometrist is a person who is trained to diagnose and treat various eye conditions, including glaucoma.


How To Self-Diagnose Glaucoma?

Glaucoma usually needs to be tested by a trained professional; however, there are newer devices available to measure glaucoma which have a decent level of accuracy.


What Are the Early Signs of Glaucoma?

There are a few warning signs of glaucoma, but these signs do not get expressed until the disease has progressed significantly. The symptoms of glaucoma include the following:
- Headache.
- Eye pain.
- Nausea or vomiting.
- Halos or rainbow-colored rings around lights.
- Blurred vision.
- Redness of the eye.


Do Glaucoma Patients Need to Wear Glasses?

For patients who have glaucoma, although the glasses do not help reduce pressure, they can help the patients adjust to the light and dark changes, as these patients suffer from reduced contrast


How Early Should One Start Screening for Glaucoma?

Depending on the risk factors, the age at which glaucoma screening starts varies. For a person who has a family history, screening can start as early as 20 years of age; however, it is recommended that irrespective of risk factors, an individual starts screening from the age of 40. It is highly recommended that those above the age of 60 undergo screening.


What Test has the Highest Accuracy Rating for Diagnosing Glaucoma?

There are a number of different tests available to test glaucoma, among which optical coherence tomography (OCT) is considered to be the most accurate and the one that can detect glaucoma at an early stage.


Is it Possible to Lead a Normal Life for a Glaucoma Patient?

In the initial stages of the disease, the patient does not recognize the signs and can go about their lives, with the disease progressing silently. It is only once the disease has become severe that it affects a patient’s lifestyle. Therefore it is best to undergo screening regularly and detect the disease at an early stage so that damage can be controlled without affecting the person’s day-to-day life.


Is Glaucoma a Disability?

 For glaucoma to be considered a disability, the following criteria have to be met such as:
- An MD of 22 decibels or more.
- The visual efficiency of better eyes is 20% or less.
- The remaining visual acuity in the better eyes is 20/200 or less.
- Unable to see more than 20 degrees to the left or right of a fixed point.

Last reviewed at:
19 Sep 2023  -  5 min read




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