R C Arnold Optometrists and Contact lens Providers
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Glossary of Terms

The following are explanations of some of the terms used on this web site:

Who are the General Optical Council?

The G.O.C. exist to protect the public and promote good eye care. They achieve this by:

  • setting standards for optical education and training, performance and conduct.
  • approving qualifications leading to registration,
  • maintaining a register of individuals who are qualified and fit to practice, train or carry on business as optometrists and dispensing opticians,
  • investigating and acting where a registrant’s fitness to practice, train, or carry on business is impaired.

What does an optometrist do?

An optometrist examines eyes, tests sight and prescribes spectacles or contact lenses for those who need them. They also fit spectacles or contact lenses, give advice on visual problems and detect any ocular disease or abnormality, referring the patient to a medical practitioner if necessary. Optometrists may also share with a medical practitioner the care of patients who have chronic ophthalmic conditions. Once qualified, optometrists can undertake further training to specialise in certain eye treatment by therapeutic drugs.

What does a dispensing optician do?

A dispensing optician advises on, fits and supplies the most appropriate spectacles after taking account of each patient’s visual, lifestyle and vocational needs. Dispensing opticians also play an important role in advising and dispensing low vision aids to those who are partially sighted and in advising on and dispensing to children where appropriate. They are also able to fit and provide aftercare for contact lenses after undergoing further specialist training. On completion, practitioners are placed onto a specialty register. At Richard C Arnold we are proud to say that all of our dispensing opticians are registered to ensure that our customers always get the best eye care products for their needs.

What is AMD?

AMD (sometimes called ARMD) means 'age related macular degeneration' It is a major cause of visual impairment in older adults (>50 years). It is unclear what causes AMD. It becomes more likely as a person ages because, over time, the cells in the macula become damaged and worn out.

What is Astigmatism?

Astigmatism is a common condition and is usually present from birth. Two-thirds of people with short-sightedness also have significant astigmatism. Astigmatism occurs when the front part of the eye, the cornea, is not a regular symmetrical spherical shape. Instead, its shape is rather like that of the back of a spoon - longer in one direction than another. Because the cornea is an irregular shape, the eye can't focus light passing through it sharply on to the back of the eye or retina. Hence the lens to correct this condition needs to be stronger in one meridian (axis) of the lens compared to another.

What is the Cornea?

The cornea is the transparent front part of the eye that covers the iris and pupil and which allows light to enter the eye. Because of it's curvature, the cornea refracts light and provides approximately two-thirds of the eye's total optical power.

What is Diabetes?

Diabetes is where your body either doesn't make enough insulin or can't use its own insulin as well as it should. This causes sugars to build up in your blood and can result in serious health complications including heart disease, blindness and kidney failure.

What is Diabetic Retinopathy?

Diabetic Retinopathy is the term meaning the changes to the retina that can occur as a result of having diabetes, such as the growth of abnormal new blood vessels and fibrous tissue.

What does 'dilation' or 'to dilate the pupil' mean?

The pupil changes size depending upon the current light levels. In order to view the interior of the eye it is sometimes necessary to dilate the pupil which means to use eye drops which will cause the pupil to open out. This can result in discomfort (especially in bright conditions) until the effect of the drops has worn off and the pupil can again close down to the correct size given the current lighting conditions.

What is a Dioptre?

A dioptre, or diopter, is a unit of measurement of the optical power of a lens or curved mirror. In humans, the total optical power of the relaxed eye is approximately 60 dioptres.

What is Glaucoma?

Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed resulting in reduced vision. In most people this damage is due to an increased pressure inside the eye - a result of blockage of the circulation of aqueous, or its drainage. In other patients the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibres themselves

What is High Blood Pressure?

High Blood Pressure (or hypertension) means that the body's blood pressure is higher than normal for extended periods of time. This higher pressure puts extra strain on the heart and blood vessels and increases the risk of a heart attack or stroke. It can also result in damage to the retinal blood vessels resulting in seriously impaired vision. This damage is called Hypertensive Retinopathy

What is High Cholesterol?

High Cholesterol means that there are higher than normal levels of Cholesterol (a waxy fat like substance) in the bloodstream. This excess cholesterol may be deposited in arteries causing blockages resulting in a number of conditions including heart disease. It can also result in damage to the blood vessels of the retina.

What is Hyperopia?

Hyperopia, commonly known as long sightedness or far sightedness is where the eye is unable to focus on close objects, but can focus on distant objects.

Hypertensive Retinopathy

Hypertensive Retinopathy is the condition of damage to the retinal blood vessels due to high blood pressure. If untreated, this can result in head aches, damaged vision and eventually blindness.

What is Lazy Eye?

'Lazy eye' (known as amblyopia) is a decrease in vision on one or both eyes without any detectable physical reason and therefore cannot be corrected by wearing spectacles or contact lenses.

What is the Macula?

The macula is the small area in the retina that contains special cells that are especially sensitive to light. The macula enables people to see fine details clearly.

What is Macular Degeneration?

Macular Degeneration is damage to the macula which results in a loss of vision in the center of the visual field. See also AMD.

What is Myopia?

Myopia, commonly known as short sightedness or near sightedness is where the eye is unable to focus on distant objects, but can focus on close objects. People suffering from myopia are referred to as myopes.

What is an Ophthalmoscope?

An ophthalmoscope is a hand held instrument used to examine the internals of the eye.

What is Presbyopia?

Presbyopia describes the condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Presbyopia's exact mechanisms are not known with certainty, however, the research evidence most strongly supports a loss of elasticity of the crystalline lens inside the eye.This process starts in childhood, with the eye becoming less and less able to resolve objects near to. This only becomes a problem when the closest point for comfortable close vision is further away than your arms length! For more information, see our Presbyopia Advice page.

What is the Pupil?

The pupil is the black looking circular opening at the center of the eye which allows light to enter the eye. It varies in size depending upon the current light levels.

What is the Retina?

The retina is the light sensitive tissue that forms a lining at the back of the eye that converts images into electrical impulses which are sent to the brain.

What is Squint Eye?

A squint means a misalignment of the eyes which may result in other problems such as Lazy Eye.

What ia a Topographer

A Topographer can be a person who studies the shape of a surface. However, in the context of optometry, it is a machine used to measure the shape of the cornea or retina.