Eye Defects
One of the greatest gifts for us humans is the power of vision. It is through which we experience the colourful world around us, enjoy its beauty, and be aware of probable threats. Without this ability, life would be thrown into dark uncertainty. But it is not only the unavailability of vision that concerns us but also experiencing only a fraction of it. Eye Defects are not as uncommon as we might think. We may be unaware of what the slight trouble in our vision can lead us to.
Myopia
Myopia, also called near-sightedness, is a condition in which the light rays from distant objects converge too soon and are brought to focus before reaching the retina. It is caused by the cornea or lens that is too convex or an eyeball of too great depth. This defect is corrected by wearing a concave lens, which causes parallel rays of light to diverge before they converge and focus on the retina.
Hypermetropia
It is also known as long-sightedness. In this condition, nearby objects appear blurred because the rays of light from near objects do not converge soon enough and are brought to focus behind the retina. It is caused by the flattened condition of the lens or cornea, or the eyeball is shorter than normal. It is corrected by using a convex lens that focuses the light rays at a shorter distance.
Astigmatism
Astigmatism is a more complicated condition in which the curvature of the cornea or the lens is irregular, causing horizontal and vertical rays to be focussed at two different points on the retina. It is corrected by using cylindrical glasses.
Presbyopia
This condition is due to the loss of flexibility of the lens located in the eye. It creates difficulty in focussing on the near object. This condition can easily be corrected by using a convex lens.
Cataract
It is a condition in which the lens becomes opaque either due to aging or some disease and leads to blindness. The only cure for cataract is the removal of the defective lens and wearing suitable glasses to substitute the removed lens or by replacing the defective lens with a normal lens from a donor.
The cornea may also become opaque. This is a serious condition and is corrected by grafting a new cornea.
Glaucoma
Over-production of vitreous humour (It is a clear, colourless fluid that fills the space between the lens and the retina of our eye) increases pressure on the delicate retina and crushes its delicate cells, causing blindness.
This condition can also happen due to the increased pressure of aqueous humour in the anterior chamber because of the blocking of its drainage. This condition of increases intraocular pressure is called glaucoma.
Night Blindness
The inability to see in dim or diffused light is called night blindness. It is because of the failure of visual purple (rhodopsin) pigment by the rod cells. The formation of rhodopsin requires Vitamin-A. Deficiency of Vitamin A causes this Eye Defects.
Colour Blindness
The inability to distinguish various colours is called colour blindness, such as a failure to distinguish red and green colours. It is usually a hereditary disorder that means genes are inherited from biological parents. Colour blindness is found to be more common in males as compared to females.
Squint
It occurs when the two eyes are not correctly attached in the eye orbits but converges more, leading to “cross eyes.” In the opposite condition, the eyes diverge outwards, leading to a “wide eye.” Both conditions may be corrected by surgical operation and Squint Eye Exercise.
Detachment of Retina
In this defect, the retina detaches from the choroid, and fluid accumulates between these layers, causing distorted vision and blindness in the corresponding field of vision.