Glaucoma is an eye disease that damages the optic nerve leading to progressive, and irreversible vision loss.It is important to note that it is NOT related to cancer and is most often caused by a buildup of pressure inside the eye.
It is often called the “silent thief of sight” because the loss of vision occurs gradually, over a long period of time, and symptoms only occur when the disease is quite advanced. It is the second leading cause of blindness after cataracts.
Glaucoma usually occurs when pressure in the eye increases. There is a small space in the front of the eye called the “anterior chamber”. Liquid flows in and out of this chamber and it nourishes and bathes nearby tissues. With glaucoma, this fluid drains too slowly out of the eye, and due to the fluid buildup, pressure inside the eye rises. This increase in pressure, called, intraocular pressure, damages the optic nerve and unless pressure is reduced, the optic nerve and other parts of the eye can be irremediably damaged. When a significant number of nerve fibers are damaged, blind spots start developing in the field of vision. Once that happens,, the damage becomes permanent.
Types of glaucoma:
Glaucoma can be divided into two main categories: “open angle” and “closed angle” glaucoma. The “angle” here refers to the angle where the iris meets the cornea. Normally, the angle is wide and open allowing the fluid to drain, thereby relieving internal pressure. When the angle is narrowed or closed, fluid doesn’t flow as quickly as it should, and as a consequence causes pressure buildup.
- “Open angle” glaucoma is painless and often occurs over a period of time. Due to the gradual development of this type of glaucoma, symptoms often go unnoticed.
- “Closed angle” glaucoma can occur suddenly, and people usually experience sudden pain and rapid vision loss. Due to the sudden appearance of symptoms , many seek medical help immediately, resulting in prevention of any permanent damage to the eye. Symptoms normally include sudden eye pain, blurred vision, redness, mid-dilated pupils, and vomiting.
Glaucoma can be primary or secondary:
Primary open-angle glaucoma: it is the most common type of glaucoma, accounting for 90% of the cases in the United States, but fewer in Asian countries. It refers to the slow clogging of the drainage canals, causing a buildup of pressure and therefore a slow and gradual damage to the optic nerve.
Secondary glaucoma: This refers to glaucoma caused by an external factor, such as disease, trauma, drugs or procedures. This increase in pressure results in optic nerve damage and vision loss, and can be either mild or severe. It can be caused by an injury, inflammation, a tumor, or an advanced case of cataract or diabetes.
Is there a relation between glaucoma and cancer?
Glaucoma can be a result of a tumor in the eye. Certain tumors within the globe can lead to changes in pressure and thereby cause permanent damage to the ocular structure. The type of tumor, the location, the malignancy, and the size of the mass all affect the changes in intraocular pressure.
Systemic cancer can spread to the eye and lead to an increase in pressure, thereby causing glaucoma. The majority of tumors that are found in the ocular tissues are generally from other sources. These tumors spread to the eye through the lymphatic system. Most of the systemic tumors affect the choroid with breast, lung, and kidney being the common primary sites of tumor formation. The prevalence of ocular metastasis from systemic tumors is estimated to be around 4%.
Glaucoma is also a possible complication of cancer treatment. It is most common among patients who have received taxanes, such as paclitaxel or docetaxel.
If not diagnosed early, the tumor’s effect on eye pressure or spread of the tumor itself can be sight or life threatening.