24-30
Oct
Glaucoma is an eye disease that typically shows no symptoms in its early stages. Without treatment, however, it can progress to blindness. The positive news is that with regular eye exams, early detection, and treatment, vision can be preserved.
To diagnose glaucoma accurately and safely, your eye doctor will assess five key factors during a glaucoma screening:
- Tonometry (Eye Pressure Test): Measures the intraocular pressure (IOP) within the eye.
- Ophthalmoscopy (Optic Nerve Examination): Evaluates the shape and color of the optic nerve, often using a dilated eye exam.
- Perimetry (Visual Field Test): Assesses the full range of vision.
- Gonioscopy (Drainage Angle Exam): Examines the angle where the iris meets the cornea to check for blockages.
- Pachymetry (Corneal Thickness Test): Measures the thickness of the cornea, which can affect pressure readings.
These tests together give a comprehensive picture of eye health and can help in early glaucoma detection.
During tonometry, also known as the eye pressure test, eye drops are applied to numb the eye. A doctor or technician then uses a device called a tonometer to apply slight pressure to the eye and measure intraocular pressure (IOP). Normal eye pressure typically falls between 10–21 mm Hg (millimeters of mercury). However, glaucoma can still develop in some people with pressures within this range, so individual assessments are essential.
Eye drops are used to dilate the pupil, allowing the doctor to examine the optic nerve's shape and color with a special lens. After dilation, you may need to wait briefly for the drops to take effect. The doctor will then use a magnifying device to shine light on the optic nerve, checking for signs like cupping or discoloration, which could indicate glaucoma.
Laser-based imaging technologies, especially Optical Coherence Tomography (OCT), are also commonly used to examine the optic nerve. OCT uses laser reflections (similar to how ultrasound measures sound reflections) to measure the thickness of the nerve fiber layer. By capturing images of the optic disc over time, OCT helps monitor any progressive loss in optic nerve fibers.
Perimetry, or "visual field testing," maps your field of vision, helping your doctor assess any potential impact of glaucoma on your sight.
For this test, you will be asked to look straight ahead and press a button each time you see a spot of light appear in your peripheral (side) vision. These light spots will vary in brightness, with some easy to see and others more challenging to detect, even for those with normal vision. It's best to stay relaxed, blink normally, and respond as accurately as you can. If you miss a spot, don't worry—those areas are automatically retested. It's worth noting that your performance may vary if tested when you're tired, such as after a long day.
Your doctor may ask you to repeat the test to confirm consistency in results. Once glaucoma is diagnosed, visual field tests are generally recommended once or twice a year to monitor for any changes in your vision.
Gonioscopy is a diagnostic exam used to assess whether the angle where the iris meets the cornea is open or closed. During the exam, eye drops are applied to numb the eye, and a special hand-held lens with a mirror is gently placed on the eye. This mirror allows the doctor to examine the drainage angle to determine its condition.
Pachymetry is a quick, painless test to measure the thickness of the cornea—the clear, dome-shaped surface at the front of the eye. A small probe is placed on the eye to take this measurement. Corneal thickness can influence eye pressure readings; for instance, a thicker-than-average cornea may yield a higher reading, while a thinner cornea might show a lower reading than the actual pressure. By measuring corneal thickness, your doctor can better interpret eye pressure results and customize an appropriate treatment plan.
NEWSLETTER SIGNUP
Keep in touch with us. We usually send about one update email monthly
Subscribe and receive our brochure