Glaucoma doesn’t typically produce any symptoms or pain until noticeable vision loss occurs. Therefore, yearly eye exams are important to allow your eye doctor to detect these silent symptoms.
Besides measuring the inner eye pressure, your eye doctor may recommend tests if he suspects any signs of glaucoma. These tests allow the doctor to objectively quantify the health of the optic nerve as well as the function of the visual pathway all the way back to the vision centers of the brain.
1. Optical Coherence Tomography, or OCT, enables the doctor to take measurements and images to better visualize your optic nerve. This instrument is a lot like an ultrasound machine, but instead of using sound waves, light waves are used to get a high definition picture of the eye and measurement of the thickness, size, and shape of your optic nerve. Some OCTs can do pachymetry or measurements of the thickness of the cornea. A thick cornea can influence intraocular pressure readings.
2. A visual field analyzer is an instrument that maps your complete field of vision. The visual field is commonly represented as a hill, or island of vision. The height or sensitivity of the normal hill of vision is affected by age, the amount of ambient light, stimulus size, and stimulus duration. If a visual field defect is present, the doctor will observe a statistically significant depression of sensitivity compared to the normal hill of vision. Interestingly, field defects that are quite evident on visual field results usually are not perceived by the patient. This is due to the ‘filling-in’ effect. This is why patients seldom tell us about symptomatic visual field loss and why we must rely upon visual field testing to detect such damage.
Lastly, the doctor may perform a gonioscopy. This part of the exam a patient is given drops to numb the eye. A hand-held contact lens with mirrors is placed on the eye. This special lens allows the doctors to see the angle between the iris and the cornea. This angle helps drain fluid and keep healthy eye pressure. If the angle is closed, blocked, or narrow, it can be a reason the pressure is high and therefore, causing damage to the optic nerve.
Berdhal, J. (2019). Glaucoma: symptoms, treatment and prevention. All About Vision. Retrieved December 13, 2019, from http://allaboutvision.com/conditions/glaucoma.htm
Five common glaucoma tests. Glaucoma Research Foundation. Retrieved December 13, 2019, from http://glaucoma.org/glaucoma/diagnostic-teset.php