Glaucoma is diagnosed with a thorough eye examination.
1. Intraocular pressure (IOP) measurement: IOP can be measured using different methods. In the normal population, IOP is 22 mmHg or lower in 98% of people. The pressure difference between two eyes is usually less than 4 mmHg. IOP measurement alone doesn't show that a person has or doesn't have glaucoma.
2. Corneal thickness measurement (pachymetry): It is very helpful for the doctor in deciding to start medication in some patients. In the normal population, corneal thickness is around 530 microns on average. There can be false-high eye pressure measurements in patients with thicker cornea and eye pressure can be measured to be lower than it actually is in patients with a corneal thickness less than 500 microns.
3. Computer vision area measurement: This is important in the diagnosis and follow up of glaucoma.
4. Optic nerve head and fiber measurement (Scanning Laser Ophthalmoscopy): We can quantify the glaucoma-related cupping in the optic nerve head and damage due to thinning nerve fibers. This is important both in diagnosis and in follow up.
Glaucoma may develop in anyone and the only way of preventing loss of vision due to this disease is early diagnosis. The patient cannot notice loss of vision unless there is marked damage to the visual field because of glaucoma. Therefore, it is important that regular eye examinations and checks are made at yearly intervals. In particular, 2 out of 100 people older than 40 years are at risk of developing glaucoma and this risk increases with age. So annual eye exams are very important.