The unconscious ability to assess the distance you are away from an object or two or more distant objects are away from each other. Requires the use of two eyes working together.
D (Depth Perception to Dry Eye)
All diabetics, regardless of age, should have regular eye examinations and monitor their blood sugar level to prevent a number of complications such as cataracts or increased optic nerve damage in the case of glaucoma. There may also be a weakening of the retinal blood vessels (diabetic retinopathy) causing them to leak leading to reduced nourishment of the retina or scarring resulting in cloudy or even loss of vision if left untreated.
The scattering of the rays of light as it passes through a substance such as water glass or plastic or strikes an object.
An optical unit of power. When preceeded by a plus sign indicates that the patient is longsighted and that the rays of light passing through the lens will converge on a point of focus.The wearer when unaided can see distance but not near. A minus sign indicates being shortsighted which is opposite to the above with the rays diverging as it passes through. One dioptre is equal to one metre of focal length while two dioptres is only half a metre.
Double vision. Caused when the muscles of each eye are not working together leading to two seperate images of a single object instead of one superimposed each upon the other.
An often hereditary condition where the top eyelid unconrollably sags due to a malfunction of the lid muscle. Requires surgical intervention. See blepharoplasty and blepharospasm.
Small yellow or white deposits on the head of the optic nerve or the retina. A common early indication of age related macular degeneration. Drusen (plural) on its own does not indicate that the condition is either present or a certainty rather that the eye is at risk.
Not only caused by the lack of tear production by lacrimal gland (tear gland) but also by its composition. Most common in the elderly. Symptons consist of irritation and redness as well as excessive tearing. Aggravated by air conditioning, smoke, dry climates and wind.