Pinguecula
A pinguecula is often referred to as a fatty degeneration of the conjunctival tissue, but it may also reflect deposits of lipids from serous exudate.
The fine, nearly transparent collagen fibers of the conjunctiva degenerate and are replaced by thicker, yellowish, more durable fibers and sometimes calcium crystals.
This causes the elevated, yellow and sometimes whitish glistening area located near the cornea.
There is no effect on vision by a pinguecula, which can appear after only a brief exposure to damaging irritation, such as excessive dryness or sun (ultraviolet radiation).
The tissue damage increases with continued exposure.
It might take only a day or two to notice a new pinguecula but weeks or months for it to resolve.
Removing the source of irritation and providing artificial lubricating drops may shrink and eliminate pingueculae in their early stages;
however, long-standing pingueculae do not respond well to treatment and may be permanent.
Pinguculae may indicate vitamin A deficiency.
Example of Pinguecula:
© Image from Photo Library of Jon Miles
Pterygium
A pterygium, although produced in a similar way as a pinguecula, often has inflammed blood vessels infusing into it. A pterygium does not emerge from a pinguecula.
Unlike a simple pinguecula, a pterygium often is progressive and will involve the cornea if left unchecked. It is triangular in shape, with the base of the triangle located in the conjunctiva and the apex of the triangle encroaching onto the cornea.
With corneal involvement, even if arrested surgically, a pterygium can affect vision by warping the surface of the cornea and inducing astigmatism, and/or by actually growing over in front of the pupil and obstructing the entering light.
Removing the source of irritation and providing artificial lubricating drops may slow down or halt the growth of pterygia;
however, sometimes surgical intervention is necessary to prevent a further decrease in vision.
Example of Pterygium:
© Image from Photo Library of Jon Miles
Bitot Spots
Bitot spots are superficial, irregularly-shaped, foamy gray or white patches that appear on the conjunctiva,
the membrane that covers most of the eyeball.
Bitot spots are one of the oldest recorded medical conditions.
The ancient Egyptians treated this condition with animal liver more than 3500 years ago.
Composed of accumulation of keratinized epithelial debris and secretions,
Bitot spots develop into a condition called xerophthalmia if not treated.
Bitot spots are usually accompanied by night blindness.
Eye ulcers develop and the cornea turns to mush (melts) if Bitot spots are not treated.
This can result in irreversible blindness.
This is an example of an ocular manifestation of a systemic disease.
Bitot spots are most likely due to severe vitamin A deficiency.
Bitot spots are also known to occur in people with fat and vitamin malabsorption.
Total blindness caused by tissue death due to a severe vitamin A deficiency cannot be treated.
Example of Bitot Spots:
Dry Eye (Xerophthalmia)
Xerophthalmia is extreme dryness and thickening of the conjunctiva, often resulting from a deficiency of vitamin A.
Reported incidence of xerophthalmia is rapidly increasing.
Xerophthalmia can be associated with systemic diseases such as Sjögren' s syndrome, systemic lupus erythematosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, and hypothyroidism; and deficiency of vitamin A.
Xerophthalmia results from inadequate function of the lacrimal glands which produce tears.
When xerophthalmia is due to vitamin A deficiency, the condition begins with night blindness and conjunctival xerosis (dryness of the eye membranes)
and progresses to corneal xerosis (dryness of the cornea), and, in the late stages,
to keratomalacia (softening of the cornea).
Vitamin A deficiency (with xerophthalmia) is associated with malnutrition and diahrrea and is the major cause of blindness in children.
Example of Xerophthalmia:
Abnormal Vascular Topography
Studies of the vessel configuration in the bulbar conjunctiva have shown that abnormal vessel topography is an indicator of various cardiovascular diseases.
Example of Vessel Coiling:
© Image from Photo Library of Jon Miles
