Several investigations are used to supplement clinical examination, both to diagnose glaucoma and to set a baseline against which to monitor the effectiveness of treatment or the rate of disease progression over time.
Optic Nerve Imaging
Stereo-photography documents the 3D structural appearance of the optic nerve head as seen clinically. Laser imaging is used also to make precise measurements of the optic nerve and the surrounding nerve fibres of the retina. These tests can aid diagnosis and set a baseline to help detect any structural change over time.
Visual field testing
Glaucoma damage causes areas in the field of vision to fade or disappear. These can be mapped by measuring how bright each of an array of spots of light needs to be before it is seen. The results are compared to eyes with normal vision. Repeated testing over a long period shows whether visual function is stable or changing.
Corneal central thickness measurement
Having a naturally thinner than usual cornea is associated with increased risk of developing glaucoma, quite apart from any confounding effect on the accuracy of eye pressure measurement. The threshold for recommending treatment is often lower in such eyes. Having corneal laser refractive surgery to correct myopia makes the cornea thinner and lowers measured eye pressure.
24 hour eye pressure measurement
Eye pressure fluctuates over the day. Measurements taken during clinic may be lower than at other times. If glaucoma is progressing but pressure readings in the clinic are normal, measuring at intervals over a day may explain why.