Glaucoma is diagnosed by performing the following 4 essential tests:
- Measurement of intraocular pressure with a tonometer (see How is tonometry done?).
- Gonioscopy to view the drainage angle (trabecular meshwork) and see if it is open or closed (see How is gonioscopy done?).
- Examination of the structure of the optic nerve (see How is the optic nerve examined?).
- Evaluation of function of the optic nerve (visual field / perimetry) (see How is the visual field examined?).
In addition to these basic exams, additional tests that may be performed include:
- Pachymetry (corneal thickness): helps interpret eye pressure measurements.
- Special visual field tests (Frequency doubling / Short wave perimetry): to assess different aspects of visual function.
- Imaging of the optic nerve and retinal nerve fiber layer with machines such as the HRT, GDx or OCT: to assess and quantify the presence of glaucomatous structural damage.
- Additional evaluation of the angle with Ultrasound biomicroscopy (UBM) / anterior segment optical coherence tomography (ASOCT) Of note, these exams are required in just a few cases, as usually gonioscopy exam is enough to evaluate the angle.