Opsins are the pigments involved in photoreception. Other pigments, such as melanin, are used to shield the photoreceptor cells from light leaking in from the sides. The opsin protein group evolved long before the last common ancestor of animals, and has continued to diversify since.[2]

Keratoconus Special contact lenses can help this condition that changes the shape of your eye. You can submit a question on the Ask the Eye Doctor About Keratoconus page. Also read more about keratoconus on our Keratoconus FAQ and Intacs for Keratoconus pages.

Chalazion A swollen bump in the eyelid. Learn about causes and treatments.

Photophobia (Light Sensitivity) Sensitive to light? Many eye conditions can cause this problem.

Stye What causes styes in your eyelid — and how to prevent and treat them.

CMV Retinitis About 80 percent of adults have been exposed to the cytomegalovirus (CMV), but it mostly affects people with poor immune systems, such as AIDS patients.

However, in the compound eye, the resolution is related to the size of individual ommatidia and the distance between neighbouring ommatidia. Physically these cannot be reduced in size to achieve the acuity seen with single lensed eyes as in mammals. Compound eyes have a much lower acuity than vertebrate eyes.[40]

Macular Hole Suddenly blurry or distorted vision, especially in seniors and diabetics, may mean a macular hole.

Cataract Surgery It's the most common non-elective surgery in the United States. Recent innovations include laser-assisted cataract surgery. See also: Cataract Surgery Cost | Cataract Surgery Recovery | Choosing a Cataract Surgeon | Cataract Surgery Complications | Intraocular Lenses (IOLs) | Crystalens & Accommodating IOLs | Multifocal IOLs | Mixing Multifocal Lenses | IOLs for Presbyopia FAQ | Toric IOLs for Astigmatism | A Cataract Surgeon Undergoes Cataract Surgery

Many small organisms such as rotifers, copepods and flatworms use such organs, but these are too small to produce usable images.[1] Some larger organisms, such as scallops, also use reflector eyes. The scallop Pecten has up to 100 millimetre-scale reflector eyes fringing the edge of its shell. It detects moving objects as they pass successive lenses.[1]

Peripheral Vision Loss "Tunnel vision" can have various causes, including glaucoma.

Complex eyes can distinguish shapes and colours. The visual fields of many organisms, especially predators, involve large areas of binocular vision to improve depth perception. In other organisms, eyes are located so as to maximise the field of view, such as in rabbits and horses, which have monocular vision.

Corneal Abrasion (Scratched Eye) A scratched cornea is usually very painful. What to do if it happens to you.

Using your smartphone in bed in the dark can cause a temporary loss of vision, eye experts are warning.

Another view of the eye and the structures of the eye labeled

The connection between eyes and love is well-documented in poem and prose since time immemorial, the stuff of whimsical fairytales and heroic legends. But while beauty may be in the eye of the beholder, evidence increasingly suggests our brains are hardwired to both display and notice visual "clues" when it comes to a potential love interest.

There is at least one vertebrate, the spookfish, whose eyes include reflective optics for focusing of light. Each of the two eyes of a spookfish collects light from both above and below; the light coming from above is focused by a lens, while that coming from below, by a curved mirror composed of many layers of small reflective plates made of guanine crystals.[15]

Eye Injury: A Guide to Treatment Accidents cause many kinds of eye injuries, from corneal scratches to penetrating wounds. What to do for an eye emergency.

Acute incidence rates for nasal, eye, and throat irritation, and coughing and breathlessness were found to be associated with increased exposure levels of both exposure indices. Steeper exposure-response slopes were seen when short term exposure concentrations were used. Results from multivariate logistic regression analysis suggest that current smokers tended to be less sensitive to the exposure to airborne sodium borate dust.[61]

Eye and Vision News Breaking news about eye care and vision problems.

Fuchs' Corneal Dystrophy Causes loss of vision and clouding of the cornea due to degeneration of the corneal endothelium and corneal edema.

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Burning Eyes How to get relief from burning, stinging eyes.

Milia (Eyelid Cysts) - New! What causes those tiny eyelid cysts in babies and adults, and how they are treated.

But researchers at the University of Georgia have discovered that a simple technique that measures visual processing speed can more easily provide information about executive cognitive abilities.

Losing an Eye: Enucleation and Prosthetic Eye FAQ FAQ about eye removal surgery (enucleation) and glass eyes.

The gap between tissue layers naturally formed a bioconvex shape, an optimally ideal structure for a normal refractive index. Independently, a transparent layer and a nontransparent layer split forward from the lens: the cornea and iris. Separation of the forward layer again formed a humour, the aqueous humour. This increased refractive power and again eased circulatory problems. Formation of a nontransparent ring allowed more blood vessels, more circulation, and larger eye sizes.[33]

In addition, other measures are proper lid hygiene, avoidance of eye rubbing,[69] and proper use of personal products and medication. Eye make-up should be used with care.[70]

Eye and Vision Product News New eyewear and vision care products designed to improve your life.

Please keep in mind that these articles are for general education purposes only. If you suspect you have an eye condition or vision problem or you have injured your eye, see an eye doctor immediately.

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Have questions about an eye condition or vision problem? Browse our extensive list of doctor-written and doctor-reviewed articles for reliable, easy-to-understand information.

When it comes to eye color and attraction, green eyes are seen as most attractive, according to an AllAboutVision.com eye color poll of more than 70,000 people. But when it comes to matters of the heart, research suggests most people do not have an eye color preference. In fact, it appears "the look of love" is all about the pupils.

Blurry Vision Blurry vision has many causes, from fatigue and eyestrain to serious eye diseases such as glaucoma. A video helps explain blurry vision causes and treatments.

Executive cognitive abilities include shifting attention between different tasks, planning, organizing and problem solving.

Ocular Rosacea How to solve eye and eyelid irritation.

Macular Dystrophy Central vision loss can be associated with this inherited eye disease.

Eye, the international review of graphic design, is a quarterly printed magazine about graphic design and visual culture

The adjustment to close-range vision involves three processes to focus an image on the retina.

Lingering eye contact also is a strong indicator for a potential love match. A 2009 study published in Archives of Sexual Behavior found that a man who rated a woman as attractive held eye contact for an average of 8.2 seconds, which increased his chances of "love at first sight," researchers said. If a man's gaze was around 4 seconds, the research suggests he was less than impressed.

The eye is made up of three coats, enclosing three transparent structures. The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera. The middle layer, known as the vascular tunic or uvea, consists of the choroid, ciliary body, and iris. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels, which can be seen in an ophthalmoscope.