Eye Health

Glaucoma - an Overview of Causes, Types and Treatment

Written by
Dr. David J Mathew
and medically reviewed by iCliniq medical review team.

Published on Nov 09, 2016 and last reviewed on Sep 07, 2018   -  3 min read

Abstract

Abstract

Most people know glaucoma as a disease associated with high intraocular pressure that is pressure in the eye. I have explained in detail about glaucoma, its causes, types, symptoms, investigations and treatment in detail in this article.

Glaucoma - an Overview of Causes, Types and Treatment

Glaucoma is an optic neuropathy, which is a disease of the optic nerve that generally progresses over time. The optic nerve connects the eye to the brain. The optic nerve damage due to glaucoma is evident in the optic nerve head, the place where the optic nerve is connected to the back of the eye. Due to the optic nerve damage, there are changes in the visual field of the patient. The major modifiable risk factor in glaucoma is the intraocular pressure (IOP).

What Causes Glaucoma?

The fluid inside the eye is called aqueous humor or aqueous. This fluid (99% water) is produced by the ciliary body in the eye. Most of the drainage of the aqueous occurs through a structure known as the trabecular meshwork. Mechanical or functional block of trabecular meshwork leads to impaired drainage and resulting in increased pressure inside the eye.

Types of Glaucoma:

Based on whether a good portion of the drainage site is visible on examination or not, glaucoma is categorized into open angle glaucoma (visible) and angle closure glaucoma (not visible). The ophthalmologist performs a test called gonioscopy to view the angle of the front part of the eye. The trabecular meshwork is one of the structures that make up the angle.

Risk Factors of Glaucoma:

  1. Intraocular pressure is directly proportional to the risk of developing glaucoma.
  2. Family history: The people with first degree relatives having primary open angle glaucoma are at a higher risk.
  3. Age and ethnicity: More in elderly and black individuals.
  4. Others: Myopia and diabetes mellitus.

Symptoms of Glaucoma:

Most patients with glaucoma do not have any symptoms until it is too advanced. As a result, many patients are diagnosed with glaucoma during an eye check up incidentally. Patients gradually lose their visual field till they are able to see only through a small island of vision. This is usually late in the course of the disease.

However, some patients who develop a sudden rise in IOP can have severe pain, headache, blurring of vision, colored halos, nausea and vomiting. This usually occurs in an acute angle closure attack when the patient suddenly develops closure of the angle leading to impaired aqueous drainage.

How Will the Ophthalmologist Examine?

Apart from the routine procedures, the IOP is checked using an applanation tonometer. This is done with a device attached to the slit lamp, the machine with which an ophthalmologist examines the eye. Gonioscopy is done using a lens suited for the purpose to visualize the angle of the eye. For both the above tests, a topical anesthetic medication is instilled to numb the eye.

The optic nerve head is examined using a lens to check for the characteristic changes of glaucoma. The area surrounding the optic disc is assessed to see if there are any obvious retinal nerve fiber layer defects. The optic nerve head assessment may require your pupils to be dilated using a dilating drop.

If there is a suspicion or if there is an evident glaucoma, then further tests may be done. These tests can be done to assess the level of damage to the optic nerve as well as the functional damage (loss of visual field).

  1. Visual field analysis using perimetry (Humphrey or Octopus or Goldmann).
  2. Optical coherence tomography can be used to assess the optic nerve head and the retinal nerve fiber layer.
  3. Heidelberg retinal tomography gives a detailed analysis of the optic nerve head.

All these tests can be done periodically to assess the progression of the disease.

Treatment:

1. Medical Treatment:

There are many eye drops, which decrease the production of aqueous or increase the drainage of aqueous from the eye, thus resulting in reduced IOP. As these usually give the desired decrease in IOP, they are usually preferred as the first line treatment.

2. Surgical Treatment:

If the IOP is too high to be reduced with medicines alone or if maximal medical therapy does not result in the desired decrease in IOP, surgical management is opted for. A trabeculectomy is usually performed to reduce IOP. There are many newer techniques and implants that can also result in reduced IOP.

3. Laser Treatment:

Argon or selective laser trabeculoplasty is aimed at the trabecular meshwork to increase the outflow of aqueous. This can be done only for some types of glaucoma. A peripheral iridotomy (burning a small hole in the iris) using laser is done in patients who are at the risk of developing angle closure glaucoma.

Going for regular follow up visit is of paramount importance. It is wise to stick to the dates of follow up visits as advised by the treating ophthalmologist. This is necessary to assess the reduction in IOP as well as progression of optic nerve head changes. A negligent attitude in patients with glaucoma can prove to be costly. Adherence to treatment and follow up schedule should be emphasized enough.

To know more about glaucoma consult a glaucoma specialist online --> https://www.icliniq.com/ask-a-doctor-online/eye-care-ophthalmologist/glaucoma

Last reviewed at:
07 Sep 2018  -  3 min read

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