Glaucoma

Definition

Glaucoma is a group of diseases that cause damage to the optic nerve. Optic nerve damage can eventually lead to visual loss, even blindness. Usually, with early detection and intervention this disease can be arrested and visual loss can be circumvented.

What is an Optic Nerve?

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Drainage canal blocked: Causing too much fluid to stay in the eye and increase pressure,

High pressure damages optic nerve. 

The hundreds of millions of fibers of the peripheral retina coalesce and ultimately form the the optic nerve. By the time they form the optic nerve, there are roughly 1.2 million fibers that communicate between the eye and the brain. The information flow is bidirectional - information goes from the eye to the brain and from the brain to the eye.

What are the types of Glaucoma?

There are basically two categories of glaucoma that are rarely related, but are classified as glaucoma because they can both damage the optic nerve.

Open Angle Glaucoma:

 

Most often, optic nerve is damaged when the eye pressure is too high. Primary open angle glaucoma (POAG) is associated with high eye pressure (IOP). Low tension glaucoma (LTG) represents progressive nerve damage despite normal eye pressure. In either scenario, the drainage of the fluid from the eye is inadequate resulting in damage to the optic nerve.

Narrow Angle Glaucoma (also known as Acute Glaucoma):

This is structural issue whereby the fluid that is constantly being made in the eye cannot flow in its usual course. As a result, the fluid builds up in the eye and causes a very high pressure that can readily damage the optic nerve. There is a classic demographic for people that are predisposed to this form of glaucoma, but not all narrow angle glaucoma sufferers meet these criteria.

 

Not every person with increased eye pressure will develop glaucoma. Some people can tolerate higher levels of eye pressure better than others. A comprehensive dilated eye exam is very important to help determine how well a person's optic nerve tolerates a particular eye pressure.

Are there specific risk factors for glaucoma?

 

Anyone can develop glaucoma. Specific risk factors for glaucoma are:

  • African Americans over age 40

  • Age > 60

  • Family history of glaucoma

  • Diabetes 

  • High blood pressure

  • Myopia - nearsightedness

  • People with thin corneas

  • People with asymmetric optic nerve cups 

  • Trauma

  • Steroid use

  • High eye pressure (IOP)

How is glaucoma detected?

 

Glaucoma is primarily detected through a comprehensive ophthalmic evaluation. A person is unlikely to detect glaucoma independently. In addition to the standard elements of an eye exam, glaucoma is usually diagnosed by:

  • Measuring the eye  pressure (Tonometry)

  • Optic Nerve examination

  • Imaging the optic nerve (Optical Coherence Tomography - OCT)

  • Visual Field Testing (Perimetry)

  • Measuring the corneal thickness (Pachymetry) 

What is the cure for glaucoma?

There is no cure for glaucoma. When vision is lost from glaucoma, it cannot be restored. The essential of glaucoma is early detection and management of the risk factors. This is an major objective of the 'routine eye exam'. 

Does increased eye pressure imply glaucoma?