Glaucoma is known as the “silent thief of vision” and is typically associated with painless and progressive loss of vision that may not produce any symptoms. Usually, peripheral vision is affected with relative sparing of central vision at early stages of disease, and when the disease gets to advanced stages, the central vision is more severely affected. Glaucoma patients may notice that they cannot see objects at their side (due to loss of peripheral visual field), but largely the patients are not able to detect any symptoms until a very advanced stage. Sometimes, patients may notice or describe that their vision has become foggy (see How does glaucoma evolve?).
Angle-closure glaucoma may be associated with redness, pain in the eye, headache, blurred vision and coloured haloes around light bulbs – acute angle closure attack presenting with quite high IOP levels (above 40 mmHg). However, most angle closure glaucoma cases evolve asymptomatically, as the clogging of the drain and IOP rise tend to occur in a slowly progressive way (see Angle closure glaucoma).
Non-specific vision symptoms may also be associated with glaucoma, like cloudy/foggy vision, glare, or needing more light to read.