An Insight into Optical Terms (Glossary)

Understanding these terms can help you communicate more effectively with your independent optometrist and make informed decisions about your eye health. Regular eye exams and proper eye care are essential for maintaining good vision and overall eye health. 

Amblyopia Often known as “lazy eye,” a condition where vision in one eye does not develop properly during childhood. Treatment may include glasses, patching the stronger eye, or eye exercises. 

Astigmatism A common vision condition caused by an irregularly shaped cornea or lens that leads to blurred or distorted vision at all distances. Corrected with glasses, contact lenses, or surgery. 

Bifocals Eyeglasses with two distinct optical powers – typically for near and distance vision. They are used to correct presbyopia in addition to other refractive errors. 

Cataract A clouding of the eye’s natural lens, leading to a decrease in vision. Cataracts can be removed surgically, with the clouded lens replaced by an artificial one. 

Conjunctivitis Also known as “pink eye,” an inflammation of the conjunctiva, the clear tissue covering the white part of the eye and the inside of the eyelids. It can be caused by infections, allergies, or irritants. 

Cornea The clear, dome-shaped front surface of the eye that covers the iris and pupil. It plays a key role in focusing your vision. 

Diopter A unit of measurement for the optical power of lenses. It indicates the degree of correction needed for nearsightedness, farsightedness, ` or astigmatism. 

Emmetropia The term for an eye that has no refractive error when the eye is at rest and can focus parallel rays of light onto the retina. 

Floaters Small specks or clouds moving in your field of vision. They are caused by tiny clumps of gel or cells inside the vitreous, the clear jelly-like fluid inside the eye. 

Fovea A small depression in the retina where visual acuity is highest. The centre of the field of vision is focused in this region, where retinal cones are particularly concentrated. 

Glaucoma A group of eye conditions that damage the optic nerve, often due to high intraocular pressure. Without treatment, it can lead to blindness. 

Hyperopia Also known as farsightedness, a condition where distant objects may be seen more clearly than close ones. Corrected with glasses or contact lenses. 

Iris The coloured part of the eye that controls the size of the pupil and thus the amount of light that enters the eye. 

Keratitis An inflammation of the cornea. It can be caused by infection, injury, or wearing contact lenses too long.

LASIK Laser-Assisted In Situ Keratomileusis, a popular refractive surgery to correct vision problems like myopia, hyperopia, andastigmatism by reshaping the cornea. 

Macula The central part of the retina, responsible for detailed central vision. Damage to the macula can lead to central vision loss. 

Multifocal Lenses are specially designed eyeglass lenses that contain multiple prescriptions within a single lens. These lenses allow the wearer to see clearly at different distances—typically close up, intermediate, and far away—without needing to switch between different pairs of glasses. 

Myopia Also known as nearsightedness, a condition where close objects are seen clearly, but distant objects are blurry. Corrected with glasses, contact lenses, or refractive surgery. 

Nystagmus Involuntary, rapid, and repetitive movement of the eyes. It can affect vision and depth perception. 

Optic Nerve The nerve that transmits visual information from the retina to the brain. 

Presbyopia The age-related loss of the eye’s ability to focus on close objects. Commonly corrected with reading glasses, bifocals or multifocal lenses. 

Pupil The black circular opening in the centre of the iris that regulates the amount of light entering the eye. 

Retina The light-sensitive layer at the back of the eye that converts light into electrical signals, which are sent to the brain. 

Strabismus A condition where the eyes do not properly align with each other when looking at an object. It can cause double vision and affect depth perception. 

Tonometry A test that measures the pressure inside the eye (intraocular pressure) to check for glaucoma. 

Visual Acuity The clarity or sharpness of vision, often measured using a Snellen chart. 

Vitreous The clear, gel-like substance that fills the space between the lens and the retina in the eye.