Glossary of Optical
Terminology

PRO-LENSES.com helps you understand the meanings of words and terms associated with vision and eye care

Accommodation

This is the adjustment of the optics of the eye to see objects at different distances. It worsens with age.

Astigmatism

A vision defect manifested by a blurry vision of objects up close and far away. It is most often inherited, but can also be caused by an eye injury. The curvature of the cornea of a person affected by astigmatism is imperfect, which means it takes an oval shape instead of a round one. This defect can be corrected with toric contact lenses. 

Blinking

Fast eyelid movement when closing and opening eyelids. The eyelid, rubbing against the eyeball, moistens its surface with tears that have a bactericidal effect and clean the surface of the eye from deposits.

Cataract

Congenital or degenerative eye disease. This is a clouding of the normally clear lens of the eye. It leads to blurred vision.

Chalazion

Chronic inflammation of the Meibomian gland.

Colour blindness

This is an inherited disease that males most often suffer from, it is characterised by colour recognition disorders.

Corneal abrasion

Corneal damage due to a scratch, abrasion or UV rays.

Eyeball

Eye as a whole. It is egg-shaped with a diameter of about 2.5 cm.

Exophthalmos

Unnatural bulging of the eyeball relative to the edge of the eye socket.

Field of view

A spatial image, area seen by the non-moving eye.

Glaucoma

This is damage to the optic nerve, gradually leading to deterioration and loss of vision.

Hyperopia

A condition of the eye in which the light rays entering the eye focus behind the retina. It is caused by too short eyeball, manifesting itself in worse vision at close range. It causes symptoms of fatigue, headaches and watery eyes.

Iris

One of the elements of the eye, the colored disc constituting the anterior part of the uvea, the center contains a pupil.

Lens of the eye

The lens of the eye is located behind the iris and the pupil of the eye. It is responsible for focusing light rays on the retina.

Macula lutea

A spot located on the retina of the eye with the highest vision resolution related with the highest density of cones.

Myopia

A defect of vision manifested by a blurred vision of objects distant from us. It usually develops in childhood and adolescence, it is often hereditary. The image is created before instead of on the retina of the eye.

Photodermatosis

Hypersensitivity to ultraviolet radiation.

Photophobia

Hypersensitivity, intolerance of light.

Presbyopia

This is a natural process caused by the ageing of the lens in the eye, which affects people with both hyperopia and myopia. It is often observed after 40 years of age. It is characterized by deterioration of vision at close distances.

Pupil

The hole in front of the lens of the eye, its task is to be responsible for the amount of light falling on the retina.

Retina

Nervous tissue capable of remembering images reaching the eye. It is composed of several layers of nerve cells that are connected to the brain by the optic nerve.

Scotomas

Partial visual field deficiencies, manifested as blurred grey or black spots.

Sclera

A thick white protective layer that forms the white of the eyeball, it surrounds the eye from the side of the orbital cavity. It protects the eye.

Stigmatism

Absence of visual defect.

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