Glaucoma is a disease characterized by increased intraocular pressure, which influences the optic nerve leading to progressive loss of vision and can culminate in blindness of both eyes. Glaucoma is caused by poor drainage of the aqueous humor of the eye resulting in pressure build up in the eye (Lusthaus & Goldberg, 2019). Usually, the aqueous humor that supplies nutrients to the structures of the anterior part of the eye after which it drains through the trabecular mesh found at the angle of the eye. In some cases, this angle is obliterated leading to poor drainage of this fluid, which results in increased intraocular pressure. The raised intraocular pressure leads to destruction of the sensitive and delicate nerve fibers of the optic nerve thus leading to deterioration of vision. In most cases, glaucoma has no symptoms (Imrie & Tatham, 2016). By the time an individual is being diagnosed with the disease, much of the damage will usually have occurred. However, occasionally it presents with headache, nausea, loss of peripheral vision, nausea, vomiting, and redness of the eyes. There are two broad classes of the disease namely the open angle and closed angle glaucoma (Lusthaus & Goldberg, 2019). Open angle glaucoma is caused by chronic conditions such as diabetes. It leads into clogging of the trabecular mess, which is responsible for drainage of the aqueous humor from the eye. Closed angle glaucoma is associated with acute condition such as injury to the eye that results in obliteration of the canal of schlemm. The condition leads to accumulation of fluid within the eye hence raised intraocular pressure. Although the disease can affect virtually everybody, sections of people are at an increased risk of developing the disease. Some of the risk factors that have been associated with glaucoma include black ancestry, family history of the disease, diabetes, myopia and hyperopia, and injury to the eye among others (Lusthaus & Goldberg, 2019).
Normal Anatomy of the Parts of the Eye Affected By Glaucoma
Parts of the eye that play an important role in glaucoma include the vitreous humor, the iris, the ciliary body, the pupil, the cornea, the iris, the trabecular mesh of the eye, the angle of the eye, the optic disc of the retina and the optic nerve. Notably, accumulation of the aqueous humor is what causes glaucoma. The aqueous humor is secreted by the ciliary body, which is a muscle with fibrous ligaments that suspend and control the size of the lens (Imrie & Tatham, 2016). Once this fluid is secreted, it flows through a canal between the ciliary body and the lens into the anterior chamber of the eye through the pupil which is a tiny hole that goes through the iris and into the anterior chamber and whose major role is in light regulation. Once into the anterior chamber of the eye, the aqueous fluid flows into the angle of the eye where the fluid drains into the trabecular mesh and back into the circulation (Lusthaus & Goldberg, 2019). The angle of the eye is formed by the intersection of the iris and the cornea. The cornea and the iris meet each other at 45 degrees. Normally, the angle of the eye is usually open at 45 degrees unless there is a pathology leading to obliteration of the angle such as in closed angle glaucoma. The trabecular mesh that drains the aqueous humor is a conglomerate of tiny blood vessels and lymphatic’s that drain the fluid back into the circulation. Poor drainage of the fluid leads to increased intraocular volume, which exerts pressure on the optic disc, which is located at the center of the retina (Imrie & Tatham, 2016). The optic disc is where efferent nerve fibers of the optic nerve converge. From here, they transmit impulses to the vision centre of the brain through the optic nerve. High intraocular pressure damages the optic disc leading to blindness.
Delegate your assignment to our experts and they will do the rest.
Normal Physiology of the Parts of the Eye Affected by Glaucoma
The drainage system of the eye helps to remove excess humor from the eye after secretion by the ciliary body and this helps to keep the intra-ocular pressure well controlled. The fluid is important for providing nourishment for the anterior parts of the eye. The fluid drains through the canal of schlemm into the trabecular meshwork and back into the circulation system thus creating for fresh humor to be secreted into the eye. The cycle helps to ensure that the intraocular pressure remains within the normal limits, which does not interfere with normal vision of the eyes (Lusthaus & Goldberg, 2019).
The optic nerve is also affected by glaucoma as a result of pressure effects. The optic nerve is involved in vision. Light from an object falls on the retina where it forms an image. Impulses are generated on the optic nerve and transmitted to the visual cortex where the image is interpreted (Lusthaus & Goldberg, 2019).
Mechanism of the physiology
The body tries to maintain its various components in a balanced state. For example, the ocular pressure is constant for most people and when the body detects an abnormality in any parameter, corrective mechanisms is triggered to correct the defect (Lusthaus & Goldberg, 2019). In the case of glaucoma, there is an increase in the ocular pressure, which prompts the body to activate various mechanisms aimed at bringing the pressure back to normal.
Prevention of Glaucoma
Glaucoma can be prevented in various ways. Primary glaucoma can be prevented by treating chronic illnesses that might contribute to the development of glaucoma. For instance, ensuring good glycemic control in diabetes can help prevent development of glaucoma. Timely management and treatment of other eye conditions can prevent secondary glaucoma (Lusthaus & Goldberg, 2019). People who experience any eye symptoms should seek prompt medical attention because as earlier said, the disease is symptomless in most cases, and timely diagnosis can help in averting it.
Treatment of Glaucoma
Glaucoma can be managed medically or through surgical intervention. The whole idea of treatment is to ensure proper drainage of the aqueous humor in a bid to reduce the intra-ocular pressure. Some of the drugs used in the treatment of glaucoma fall in the following classes:
Prostaglandins- the hormones help increase the drainage of the aqueous humor through the trabecular system. This helps to get rid of the excess fluid from the eye leading to a decrease in intraocular pressure (Goldberg & Goldman, 2018).
Beta- adrenergic antagonists- these drugs reduce the secretion of the aqueous humor from the ciliary body. The process helps to prevent accumulation of excess humor in the eye thus effectively preventing the development of glaucoma (Goldberg & Goldman, 2018). The drugs have been the gold standard for medical management of glaucoma for some time now. Examples of these drugs include timolol, and levobunolol.
Carbonic anhydrase inhibitors- the drugs reduce the rate of formation of the aqueous humor. The process contributes to less aqueous humor being secreted and thus prevents the development of glaucoma. Examples of these drugs include acetazolamide, and methazolamide (Goldberg & Goldman, 2018).
Osmotic agents are used to provide immediate relief of symptoms especially in cases of acute closed angle glaucoma and in situations where the pressure remains high despite being treated with various medications. Medications include mannitol. The disease can also be managed surgically to improve drainage. Example of surgical treatment is by laser therapy. It involves making a hole in the angle of the eye to enlarge the drainage channel, which results in better drainage of the fluid (Goldberg & Goldman, 2018). Trabeculotomy is a surgical procedure used to clear clogged vessels and create a new drainage pathway of the aqueous humor. Ultimately, this leads to improved flow of the aqueous fluid thus preventing glaucoma development.
References
Goldberg, I. & Goldman, N. (2018). Fighting Glaucoma: An Action Handbook. New York, NY: Kugler Publications
Imrie, C. & Tatham, A. J. (2016). Glaucoma: the patient’s perspective. British Journal of General Practice , 66 (646): e371-e373. DOI: https://doi.org/10.3399/bjgp16X685165
Lusthaus, J. & Goldberg, I. (2019). Current management of glaucoma. Med J Aust ; 210 (4): doi: 10.5694/mja2.50020
