Glaucoma results when the pressure inside of the eye damages the optic nerve. The damage does not cause pain or offer early warning signs in the common forms of glaucoma. Doctors may notice signs on an eye exam, but, for most patients, by the time doctors diagnose glaucoma, the condition has already damaged the eye. Though glaucoma does not give early signs of the disease, awareness of the symptoms may encourage someone with signs of the condition to discuss the symptoms with an eye doctor.
Intraocular Pressure
During an eye exam, a doctor or her technician will check the eye's intraocular pressure. When a doctor sees an eye pressure slightly greater than 21, she may consider this a warning sign for glaucoma. Without additional symptoms or risk factors, the doctor may not recommend treatment. If the patient has a significantly higher pressure, a family history of glaucoma or any other risk factors, she may decide to begin treatment with eye drops to lower the pressure.
Optic Nerve
High pressures in the eye damage the optic nerve and, though this damage may take time to appear, doctors can often see damage during a dilated eye exam. Glaucoma changes occur slowly, and the doctor may not notice subtle changes between exams. The doctors may take a picture of the optic nerve and use this at the next exam to compare for changes.
Vision
The optic nerve plays an important role in vision by transmitting images to the brain. When the optic nerve has damage from glaucoma, vision changes occur. The changes happen slowly and may not be noticeable until significant damage has occurred. Glaucoma begins by taking away some of the peripheral vision. With advanced damage, glaucoma patients often describe vision as "tunnel vision," and they can only see directly ahead. If a doctor suspects or diagnoses glaucoma, he will order a test that monitors changes in side vision. The patient sits in a machine and clicks a button when he sees a light. This allows the doctor to note changes to peripheral vision over time. However, once glaucoma damages the vision, the vision cannot be corrected.
Pain and Nausea
Closed-angle glaucoma occurs in some people and results from partial or complete closure of the drainage canal inside the eye. The excess fluid the eye makes cannot drain, and the pressure builds inside the eye. This condition usually occurs in one eye at a time, and the person will have intense pain in the affected eye, followed almost immediately by severe nausea and vomiting. These symptoms require immediate care from an eye doctor to lower the pressure quickly and reduce the risk of permanent blindness.
