Interior problems

Myopia

This condition, also called short sightedness, is where light is refracted by the eye but instead of reaching the retina, its focus point lies in front of this layer of cells. This causes the patient to have a normal view on objects that are close to the body.  However, when looking at objects further away, the images appear blurred.

Causes

In patients with myopia, the length of the eyeball is too long which causes the light waves to be focused in the vitreous humour instead of the retina. This can also be caused if the refractive power of the cornea is too high.

Treatment

Myopia is usually treated by means of corrective lenses, supplied by an eye care professional. They have a concave shape in order to reduce the excessive diopters of the eye, which extends the focal point so that it rests on the retina. The condition can also be corrected by surgery; however, this has many risks during the procedure and can also promote many side effects.

Myopia diagram courtesy of Wikimedia Commons. This image is in the public domain thus free of any copyright restrictions.

Hyperopia 

A condition exists which is anatomically the opposite of myopia, in that light waves do not focus on the retina, but on a point behind it. This means that although the sufferer can see clearly at short distances, at increasing distances, this ability is lost.

Causes

Hyperopia or long sightedness results either because the eyeball is too short in length, or because the lens cannot become thick enough. Both of these result in an insufficient degree of refractive power. Therefore, light waves do not meet on the retina and a blurry image is produced.

Treatment

As with myopia, the best treatment for hyperopia is corrective glasses. They differ in shape however, instead of being concave, they are convex. These have a positive dioptric value which causes light waves to focus closer than their normal range.

 Hyperopia diagram courtesy of Wikimedia Commons. This diagram is in the public domain thus free of any copyright restrictions.

Presbyopia

Presbyopia is a naturally occurring process whereby the eye exhibits a decrease in ability to focus on close objects with age.

Causes

Presbyopia is a natural process of aging; it isn’t genetic or environmental like other eye disorders such as hyperopia. It occurs due to the change in the properties of the proteins in the lens, which causes it to become less elastic and also harder in nature. The existence of a thicker lens causes a decreased ability to see things at close distances, similar to that experienced in myopia.

Treatment

Treatment for presbyopia is similar to the other eye disorders that we have encountered. They are also recommended to wear corrective eye glasses, however, in the form of bifocals. These are glasses which contain two different points of focus. The main section of the lens is for long distance, whereas, the smaller section is designed for close viewing.

Another type of lens is called progression addition lenses. These are very similar to bifocals, however, the divide between the two types of prescriptions is much less defined.

Glaucoma

Glaucoma is a condition which exists in many different subtypes; however, they can all be described as a type of optic neuropathy. It involves the loss of retinal ganglion cells in a characteristic pattern and also affects the optic nerve. If left untreated, it can lead to permanent damage of the optic nerve as well as visual field loss. This can ultimately lead to blindness. Glaucoma is known to be the second leading cause of blindness, affecting 1 in 200 people under fifty and 1 in 10 of people over eighty. 

 Glaucoma pictures courtesy of Wikimedia commons. These images are in the public domain thus free of any copyright restrictions. 

It can roughly be divided into two main categories:

·         Closed angle glaucoma appears suddenly, is often painful and visual loss occurs rapidly. This causes the patient to seek medical attention relatively fast which means they can be treated before any lasting damage sets in.

·         Open angle, or chronic glaucoma, tends to have a slower time period of onset. This means the patient may not realize they have visual loss until the disease has progressed significantly.

  Causes

·         A large cause of glaucoma is an increase in intraocular pressure.

·         People of an older age, a decreased corneal thickness or myopia have an increased risk of open angle glaucoma.

·         Conditions which restrict blood flow to the eye, for example, diabetic retinopathy, ocular trauma, central retinal vein occlusion etc. These and the prolonged use of steroids are known as ‘secondary glaucomas’.

Treatment

Intraocular pressure can be lowered with medication, usually eye drops. Poor compliance with medications and follow-up visits is a major reason for vision loss in glaucoma patients. Checkups are important because once the loss of vision has occurred, it can never be recovered.