Eye Terms & Conditions Glossary

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You might have heard of the term LASIK eye surgery, but do you know what it means? What about Amblyopia or Esotropia? When researching anything about eye care, eye health, laser eye surgery, or sight loss you are confronted by a long list of vocabulary that you may, or may not, understand.

Here at Focus we decided to debunk and explain some of the terms in the eye care/eye health world:

Age-Related Macular Degeneration (AMD): Occurs when the small central portion of the retina, known as the macula, deteriorates. It gets the name ‘age-related’ macular degeneration as the disease tends to develop as a person ages. Find out more about AMD.

Amblyopia: Also known as ‘lazy eye’ it is a childhood condition where the vision in one eye does not develop properly. It usually affects one eye, and is a result of the brain and eye not working together.

Astigmatism: Causes blurred and distorted vision and occurs when the cornea isn’t the normal curved shape.

Bifocals: Lens with one segment for near vision and one segment for far vision. The term can apply to both eyeglass lenses and contact lenses

Binocular Vision: Both eyes work together to achieve proper focus, depth perception and range of vision.

Blepharitis: A common condition that causes inflammation of the eyelids, including the skin, lashes and meibomian glands. Blepharitis is often associated with a bacterial eye infection. Learn more about Blepharitis.

Cataract: Clouding of the natural lens of the eye. Symptoms include glare, blurred vision and a seeing a cloudy spot. Usually caused by ageing, exposure to the sun’s UV rays, smoking, steroid intake and diabetes.

Colour Blindness: Partial or total inability to distinguish specific colours. It is inherited and is more common in men than women. Read more about Colour Blindness, including symptoms and treatments, on our blog.

Cornea: The clear portion of the front surface of the eye that allows light to enter the eye for sight.

Diplopia (double vision): When two images of the same object are perceived by one or both eyes.

Dry Eye: Dry eye disease, or dry eye syndrome, occurs when the eye does not adequately produce tears, or, they evaporate too quickly. Symptoms include tenderness, redness, stinging, itching or burning of the eye. Read our article on Dry Eye Disease to learn more.

Esotropia (cross eyes): When one or both eyes point inward, so the eyes look ‘crossed’.

Exotropia (wall eyes): When one or both eyes point outward.

Floaters: A dark, grey spot or speck that passes across your field of vision and moves as you move your eye.

Glaucoma: The second leading cause of blindness. Glaucoma is a common condition where the optic nerve becomes damaged, which leads to progressive and irreversible sight loss.

Hyperopia (farsightedness): A person must exert a greater-than-normal focusing effort to see distant and near objects clearly.

Iris: The coloured part of the eye that surrounds the pupil and determines eye colour.

Lacrimal Gland: Is the tear gland. It is responsible for the continual supply of tear fluid that is wiped across the eye with every blink.

Laser-Assisted Sub-Epithelial Keratectomy/Laser Epithelial Keratomileusis (LASEK): Reshapes the cornea to correct abnormalities. The difference between LASEK and LASIK is that no flap is made in the cornea with LASEK, and it is mostly chosen when the patient is not eligible for LASIK due to anatomical reasons.

Laser-Assisted In-Situ Keratomileusis (LASIK): Is the most frequently performed laser eye surgery to correct myopia (short-sight), hyperopia (long-sight) and astigmatism. LASIK eye surgery creates a flap in the eye which changes the curvature of the cornea so that light entering the eye will be correctly focused on the retina at the back of the eye, resulting in a clear image. Learn more about LASEK and LASIK here.

Myopia (nearsightedness): A person can see near objects clearly but distant vision is blurred. The primary symptom of nearsightedness is squinting.

Oculus Dexter: the Latin term for “right eye”.

Oculus Sinister: the Latin term for “left eye”.

Oculus Uterque: the Latin term for “each eye”.

Opthalmologist: A medical doctor (MD) who specialises in the eye. They perform eye exams, treat disease, prescribe medication, and perform surgery.

Optic Nerve: The nerve that carries electrical impulses from the retina of the eye to the visual cortex in the brain.

Optometrist: Doctors of optometry (ODs) examine eyes for both vision and health problems. They also prescribe glasses and fit contact lenses.

Patching: Putting an eye-patch over the better eye when trying to improve vision because of amblyopia (lazy-eye).

Peripheral Vision: The outside edges of your visual field.

Photophobia: Discomfort from sun or other light, also known as light sensitivity.

Pupil: The round dark centre of the eye which opens and closes to regulate the amount of light the retina receives.

Retina: The light-sensing nerve tissue at the back of the eye.

Retinal Tear: A tear or split caused by a vitreous detachment. Symptoms include floaters and light flashes.

Stye: A small red bump on the edge of the eyelid caused by an infected gland. Learn more about Styes on our blog.

Trifocal: A lens design that has three focal areas. 1) a lens for close work and reading. 2) a lens for mid-distance viewing (arm’s length). 3) a lens for faraway viewing or driving.

20/20: The term “20/20” is a visual acuity measurement. Usually determined by a test of viewing distance and the ability to view letters. During the test, if you can only work out the bigger letters, at the set distance, your vision will be worse than 20/20  (e.g. 20/40, 20/60 etc.), and the smaller the letters you can work out from the same distance equals better than 20/20 vision (e.g. 20/15, 20/12, 20/10 etc.).

Visual Acuity: The sharpness of your vision. Visual acuity is measured by your ability to identify letters or numbers on a standardised eye chart from a specific viewing distance.

Visual Impairment: Visual impairment is a severe reduction in vision that cannot be corrected with standard glasses or contact lenses.




By: David

If you are interested in vision correction at Focus Clinic please call us on 0207 307 8250 and book a free consultation.

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21st Apr


‘If you are considering surgery just do it ‘

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Mr Samer Hamada
laser and lens eye surgery specialist
 Samar Hamada