At Amazing Eye Care, our certified optometrist is equipped to diagnose and treat glaucoma. Utilizing advanced technology, such as the Optomap Daytona, we excel at detecting early signs of glaucoma through thorough screening and annual scans.
Discover the multitude of tests eye doctors employ for an accurate glaucoma diagnosis. Thorough evaluation encompasses various aspects of your eye health, including eye pressure, cornea thickness, and optic nerve health. This article outlines the comprehensive assessment and tests essential for a proper glaucoma diagnosis.
Risk Factor Assessment
Your eye doctor initiates the assessment by evaluating your risk factors for developing glaucoma, which guides the frequency and extent of subsequent testing. The examination involves a family history and medical questionnaire to identify key risk factors, including:
- Age over 60
- Ethnic background, such as African or black Caribbean descent, Hispanic, or Asian
- Family history of glaucoma (e.g., a sibling or parent with glaucoma)
- History of eye conditions, injuries, or surgeries
- Prolonged corticosteroid use (eye drops, pills, inhalers, or creams)
- Chronic conditions affecting blood flow, such as migraines, diabetes, low blood pressure, or hypertension
- Current or former smoking status
For those who have undergone a comprehensive eye exam, additional factors considered include:
- Elevated eye pressure (above 21 mm Hg)
- Thin corneas (less than 500 um)
The type of eyesight also plays a role, with farsightedness associated with a higher risk of narrow-angle glaucoma (a rapidly advancing type) and nearsightedness linked to open-angle glaucoma (a slow-progressing type without symptoms).
Common Glaucoma Tests
In a comprehensive eye exam, your eye doctor routinely screens for glaucoma, irrespective of your risk level. These essential tests, tonometry and ophthalmoscopy, establish a baseline for future comparisons as you age.
Tonometry
Tonometry measures the pressure inside your eye. Your eye doctor administers numbing eye drops and uses a tonometer, applying a gentle puff of warm air.
While eye pressure varies among individuals and isn't always a definitive indicator of glaucoma, it provides valuable information for your eye doctor's assessment. Normal pressure typically ranges from 12 to 22 mm Hg (millimeters of mercury), with glaucoma often diagnosed at pressures over 20 mm Hg. However, some individuals may have glaucoma at pressures between 12 and 22 mm Hg.
Ophthalmoscopy
This entails examining your optic nerve. Your eye doctor will dilate your pupil with eye drops to observe the optic nerve's shape and color. Using a small device with a light, the optic nerve is magnified. Depending on the test outcomes, your doctor may recommend additional glaucoma exams.
Additional Glaucoma Tests
Perimetry
Perimetry is a visual field test that maps your entire field of vision. While looking straight ahead, you'll signal when a moving light enters your peripheral vision. Maintain relaxation and provide accurate responses. Your doctor may repeat the test for consistency. If you have glaucoma, an annual visual field test is typically advised to monitor any vision changes.
Gonioscopy
This diagnostic exam assesses the angle between your iris and cornea. After receiving numbing eye drops, a handheld contact lens is gently applied to the eye. Using a mirror on the contact lens, the doctor examines whether the angle is closed and blocked (indicating possible angle-closure or acute glaucoma) or wide and open (suggesting possible open-angle or chronic glaucoma).
Pachymetry
Finally, your eye doctor may employ pachymetry as an additional diagnostic tool. This test measures the thickness of your cornea, the transparent front window of the eye. A pachymeter probe is gently placed on the cornea to obtain thickness measurements. Pachymetry can enhance diagnostic accuracy, considering that corneal thickness can impact eye pressure readings.
Diagnosing glaucoma is a nuanced process, underscoring the importance of regular eye exams, especially if you possess any risk factors, for early detection.
Optic Nerve Examination
The optic nerve can be easily examined using an ophthalmoscope in a clinic. It exits through the back of the eye and is composed of over one million individual nerve fibers that originate in the retina. These fibers travel to different parts of the brain. When looking into the eye, the optic nerve is seen end on, and the nerve fibers can be faintly observed fanning out onto the retina.
In a normal state, the optic nerve head resembles a doughnut, with the outer ring made up of nerve tissue. The central nerve head contains a hole called the optic cup, which is the empty space left after the nerve fibers spread into the retina. In cases of glaucoma, the nerve fibers become damaged and deteriorate, resulting in a larger cup or hole in the doughnut shape.
A healthy optic nerve head typically has a thick outer ring of nerve tissue surrounding a small optic "cup" in the center. However, in cases of glaucomatous optic nerve damage, the outer ring becomes thin and the "cup" enlarges, indicating the loss of nerve fibers. While various diseases can affect the optic nerve, the distinct appearance caused by glaucoma allows ophthalmologists to identify its presence.