Glaucoma is an eye condition that causes gradual vision loss due to irreversible damage of optic nerve; caused by increased intraocular pressure. Glaucoma if not treated will continue to damage optic nerve, which transmits images to the brain, and will lead to permanent loss of vision causing permanent blindness. It is the second leading cause of permanent blindness across the world. Glaucoma is considered an inherited condition and progressive age is also a major risk factor.
Causes of Glaucoma
Glaucoma is caused by increased pressure within the eye, which causes damage to optic nerve fibers that are highly susceptible to increased pressure. Glaucoma is also seen in individuals with normal intraocular pressure. The risk factors for glaucoma include family history of glaucoma, age over 40 years, history of steroid use, myopia, hypermetropia and diabetes. The other causes that might lead to glaucoma are injury to the eye, inflammatory conditions, severe eye infection, blocked blood vessels in the eye and on occasion certain eye surgeries.
Types of Glaucoma
There Are Basically Two Types Of Glaucoma:
Open-angle glaucoma (wide-angle glaucoma) is the most common type of glaucoma. This is a chronic type of glaucoma and its frequency increases with age. This is caused by chronic fluid build-up within the eye due to gradual clogging of the drainage system. This type of glaucoma is asymptomatic and there is peripheral loss of vision, which is undetected in the early stages as there are no symptoms.
Angle-closure glaucoma (closed-angle, narrow-angle, acute or chronic angle-closure glaucoma) is less common type of glaucoma. In this, there is difficulty in drainage of aqueous humor due to decreased angle between iris and cornea leading to increased intraocular pressure. This might also be related to other eye conditions such as cataract or hypermetropia.
Can We Regain Lost Vision From Glaucoma?
Open-angle glaucoma is mostly symptom less, but might present with peripheral vision loss that might not be detected early in the disease process. Other symptoms might include eye pain, headache, vision loss, visual blurring, redness of the eye, and halos around lights, corneal haziness, nausea and vomiting and narrowed vision (tunnel vision). If the symptoms are not treated then it might lead to permanent vision loss causing permanent blindness. Thus, once vision is lost due to glaucoma, the lost vision cannot be regained, as there is permanent damage to the optic nerve. However, there has been evidence that in the initial stages of glaucoma the vision can be restored, but glaucoma is not detected in its initial stages as initially it is asymptomatic, which makes it hard to detect. The early vision loss can be detected with the help of Pattern Electroretinography (PERG) testing. Unfortunately, most doctors do not have PERG equipment due to its high cost and time consumption.
Diagnosis and Treatment of Glaucoma
An ophthalmologist/optometrist usually diagnoses glaucoma by measuring intraocular pressure and examining drainage angle and probable optic nerve damage. The various evaluation methods include tonometry, pachymetry, gonioscopy, ophthalmoscopy, visual field testing and confocal laser scanning systems and optical coherence tomography. An individual with the above signs and symptoms should immediately follow up with an ophthalmologist for an eye check especially if he/she is at a greater risk of developing glaucoma.
Once glaucoma is diagnosed, the visual loss due to optic nerve damage cannot be reversed, but the disease progression can be controlled with appropriate treatment measures aimed at improving intraocular pressure to prevent further nerve damage and vision loss. The various treatment measures include eye drops aimed at decreasing the intraocular pressure, if eye drop is not successful at lowering intraocular pressure then laser surgery along with continued use of eye drops or conventional eye surgery might be considered. An improvement might be seen with glaucoma treatment, but the improvement is so subtle that the patient is not able to detect it, can only be detected with careful visual field testing. This improvement is only transient as most of the improvement is lost within five years even with treatment.