Glaucoma is a GROUP of disorders. An increase in the pressure inside the eye. When the pressure is too high, damage occurs to the optic nerve. The optic nerve is made up of a bundle of nerve fibers which sends signals to the brain. Damage to the optic nerve can initially cause blind spots at the outer edges of the field of vision called peripheral or side vision. This is the main sign of glaucoma. As damage to the optic nerve gets worse, the visual field can shrink leading to tunnel vision or even loss of central vision affecting a patients ability to read. Fortunately, this occurs only in patients with very severe disease. Glaucoma can be divided roughly into two main categories, "open angle" and "closed angle" glaucoma. Closed angle glaucoma can appear suddenly and is often painful; visual loss can progress quickly but the discomfort often leads patients to seek medical attention before permanent damage occurs. Open angle, chronic glaucoma tends to progress at a slower rate and the patient may not notice that they have lost vision until the disease has progressed significantly.

Symptoms of Glaucoma:-
 

The most common types of glaucoma — primary open-angle glaucoma and acute angle-closure glaucoma — have completely different symptoms.

Primary open-angle glaucoma signs and symptoms include:

  • Gradual loss of peripheral vision, usually in both eyes
  • Tunnel vision in the advanced stages

Acute angle-closure glaucoma signs and symptoms include:

  • Severe eye pain
  • Nausea and vomiting (accompanying the severe eye pain)
  • Sudden onset of visual disturbance, often in low light
  • Blurred vision
  • Halos around lights
  • Reddening of the eye

Both open-angle and angle-closure glaucoma can be primary or secondary conditions. They're called primary when the cause is unknown and secondary when the condition can be traced to a known cause, such as eye injury, inflammation, tumor, advanced cataract or diabetes. In secondary glaucoma, the signs and symptoms can include those of the primary condition as well as typical glaucoma symptoms.