Vol.18 Eye disease

Illness in the eyes alters Vision. What are eye diseases? Here we will discuss some common eye diseases that we often hear about.

 

1. Glaucoma

Glaucoma is the most common cause of blindness in Japan (*1). This disease damages the optic nerve and reduces the field of vision.
This disease is caused by high intraocular pressure, which increases eye hardness, pressing on the optic nerve and leading to the condition. However, even if the intraocular pressure is normal, the optic nerve may not be able to withstand intraocular pressure, resulting in the disease. In addition, another type of glaucoma that occurs suddenly (angle closure glaucoma) requires attention.

2. Cataract 　

Cataracts are conditions in which the eye’s lens becomes cloudy. This can have several causes, including birth or trauma; however, in most cases, the lens becomes less transparent as it ages. In Japan, more than 800,000 people are affected (*2). Cataract surgery, which replaces cloudy lenses with artificial ones (intraocular lenses), is widely used in Japan; however, in some countries, cataract surgery is not widely used, making cataracts the leading cause of blindness.

3. Retinal detachment

The retina consists of 10 layers of transparent membranes. Retinal detachment occurs when the retina separates from the middle layers, thereby limiting the area of vision. The initial symptom is the appearance of floating black spots, known as “floaters.”

As the disease progresses, the area of vision narrows, and when it extends to the macula, the central part of the eye’s fundus, vision recovery may be impossible.

4. Diabetic retinopathy

Diabetes mellitus is a lifestyle-related disease and a well-known complication of DR. This complication occurs when the small blood vessels in the retina gradually become clogged, bleed, or sustain damaged. When the blood vessels carrying nutrients fail, new blood vessels (neovessels) form in the retina. Neovascular vessels are imperfect, fragile, and prone to hemorrhage. If hemorrhage occurs and blood flows out into the vitreous body, light from the outside has a difficult time passing through, resulting in vision loss.

5. Age-related macular degeneration (ARMD)

This disease damages the retinal macula, causing vision loss. This disease occurs with age, particularly in elderly individuals. There are two types of age-related macular degeneration: atrophic, in which the macula deteriorates, and exudative, in which new blood vessels (neovascular vessels) grow from the choroid, the outer part of the retina, toward the retina.
New blood vessels break, and blood and other substances leak, causing damage to the macula.

 

*1 References: Current status of visual impairment in Japan (2005 survey, Kimihiro Nakae et al.)
*2 References: Patient survey (FY 2014, Ministry of Health, Labour and Welfare)

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