If you develop yellow eyes, you should have blood tests to see if you have this condition and associated liver problems. As you would expect, this condition is when a normally white sclera has a somewhat blue color. Blue sclera is caused by a congenitally thinner-than-normal sclera or a thinning of the sclera from disease, which allows the color of the underlying choroidal tissue to show through it.
Congenital and hereditary diseases associated with blue sclera include osteogenesis imperfecta brittle bone disease and Marfan's syndrome a connective tissue disorder.
The Retina: Where Vision Begins
Acquired diseases such as iron deficiency anemia also can be associated with blue sclera. This is inflammation of the episclera that lies atop the sclera and under the conjunctiva. Episcleritis is relatively common and tends to be benign and self-limiting. It has two forms: The cause of most cases of episcleritis is unknown, but a significant minority up to 36 percent of people who get the eye condition have an associated systemic disorder — such as rheumatoid arthritis, ulcerative colitis, lupus, rosacea, gout and others.
Certain eye infections also may be associated with episcleritis.
Most episodes of episcleritis will resolve on their own within two to three weeks. Oral pain medication and refrigerated artificial tears may be recommended if discomfort is a problem. This is inflammation of both the episclera and the underlying sclera itself. Scleritis is a more serious and typically more painful red eye than episcleritis. Up to 50 percent of cases of scleritis involve an underlying systemic disease, such as rheumatoid arthritis. Generally, the onset of scleritis is gradual, and most patients develop severe, piercing eye pain over several days.
This pain tends to worsen with eye movements. In most cases, the inflammation begins in one area and spreads until the entire sclera is involved. Scleritis can cause permanent damage to the eye and vision loss.
Sclera Function
Frequent complications include inflammation of the cornea keratitis , uveitis , cataract and glaucoma. Scleritis typically is treated with oral non-steroidal anti-inflammatory drugs NSAIDs and corticosteroids. In some cases, immunomodulatory therapy may also be prescribed. Scleritis may remain active for several months or even years before going into long-term remission. A scleral buckle is not a condition of the sclera — it's the name of a surgical procedure used to repair or prevent a detached retina.
In the scleral buckle procedure, a band of silicone, rubber or semi-hard plastic is generally placed around the mid- to posterior sclera and sutured in place. This band pushes in, or "buckles," the sclera inward, toward the detached or torn retina, allowing the loose retinal tissue to rest against the inner wall of the eye.
The retinal surgeon then uses either extreme cold cryopexy or a specific band of focused light laser photocoagulation to seal the retinal tissue against the wall of the eyeball, repairing the torn or detached retina. Heiting has more than 25 years of experience as an eye care provider, health educator and consultant to the eyewear industry. His special interests include contact lenses, nutrition and preventive vision care.
What you need to know Color blindness test Visual acuity: Two years ago, Jordan finally found one. A doctor living in northern England, referred to only as cDa29 in the literature, is the first tetrachromat known to science. She is almost surely not the last.
Sclera | White of the Eye - Definition and Detailed Illustration
The first hint that tetrachromats might exist came in a paper on color blindness. Dutch scientist HL de Vries was studying the eyes of color-blind men, who, along with two normal cones, possess a mutant cone that is less sensitive to either green or red, making it difficult for them to distinguish the two colors. He tested their vision by having them perform a basic matching task.
Twiddling the dials on a lab instrument back and forth, the men had to mix red and green light so that the result, to their eyes, matched a standard shade of yellow. To compensate for their difficulty in discerning hues, color-blind men need to add more green or red than normal trichromats to make a match. Out of curiosity, De Vries tested the daughters of one subject and observed that even though they were not color-blind—they seemed to distinguish red and green as well as anyone—they needed more red in their test light than normal people to make the match precise.
Pondering the situation, De Vries thought he saw an explanation. Color blindness ran in families, affecting men but not women. While color-blind men had two normal cones and one mutant cone, De Vries knew that the mothers and daughters of color-blind men had the mutant cone and three normal cones—a total of four separate cones in their eyes.
He suspected the extra cone could be why the women perceived color differently—not because they saw less than most people but because they saw more.
Sclera: The White Of The Eye
He speculated that such women might be using the fourth cone to distinguish more colors than a trichromat, but he buried this insight on the last page of the paper. De Vries never wrote about four-coned women again.
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Mollon and Jordan realized that since color blindness is common, four-coned women must be as well. Jordan estimates they make up as many as 12 percent of women.
To find if tetrachromats were hidden in this group, the researchers sought out the mothers of color-blind sons and had them take matching tests similar to the one used by De Vries, but with a twist. If they were true tetrachromats, they would never be able to make a satisfactory match, because they would be able to sense color gradations beyond those available on the test.
Mollon and Jordan found that women with four cones could consistently make a match on the tests. Jordan began to have doubts. Perhaps the fourth cone was not active.
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Perhaps super-vision was not real. In Jordan, now at Newcastle, returned to testing using a new method. Sitting in a dark room, peering into a lab device, women saw three colored circles flash before their eyes. To a trichromat, they all looked the same. To a tetrachromat, though, one would stand out. That circle was not a pure color but a subtle mixture of red and green light randomly generated by a computer. Only a tetrachromat would be able to perceive the difference, thanks to the extra shades made visible by her fourth cone.
Jordan gave the test to 25 women who all had a fourth cone.