"important to note that refractive surgery is not compatible with everyone, and rarely people may find that eyewear is still needed after surgery. Recent developments also include procedures that can change eye color from brown to blue. A cataract is an opacification or cloudiness of the eye's crystalline lens due to aging, disease, or trauma that typically prevents light from forming a clear image on the retina. If visual loss is significant, surgical removal of the lens may be warranted, with lost optical power usually replaced with a plastic intraocular lens (IOL). Owing to the high prevalence of cataracts, cataract"
"due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol. The underlying mechanism involves accumulation of clumps of protein or yellow-brown pigment in the lens that reduces transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination. Prevention includes wearing sunglasses and not smoking. Early on the symptoms may be improved with glasses. If this does not help, surgery to remove the cloudy lens and replace it with an artificial lens is"
"Cloud iridescence Cloud iridescence or irisation is a colorful optical phenomenon that occurs in a cloud and appears in the general proximity of the Sun or Moon. The colors resemble those seen in soap bubbles and oil on a water surface. It is a type of photometeor. This fairly common phenomenon is most often observed in altocumulus, cirrocumulus, lenticular, and cirrus clouds. They sometimes appear as bands parallel to the edge of the clouds. Iridescence is also seen in the much rarer polar stratospheric clouds, also called nacreous clouds. The colors are usually pastel, but can be very vivid or"
"Lenticonus Lenticonus (/len·ti·co·nus/ (len″tĭ-ko´nus)) [lens + L. conus, cone] is a rare congenital anomaly of the eye characterized by a conical protrusion on the crystalline lens capsule and the underlying cortex. It can reach a diameter of 2 to 7 mm. The conus may occur anteriorly or posteriorly. If the bulging is spherical, instead of conical, the condition is referred to as ""lentiglobus"". It produces a decrease in visual acuity and irregular refraction that cannot be corrected by either spectacle or contact lenses. Biomicroscopically ""lenticonus"" is characterized by a transparent, localized, sharply demarcated conical projection of the lens capsule and"
"glaucoma, though not simple conjunctivitis. A ciliary flush is a ring of red or violet spreading out from around the cornea of the eye. The cornea is required to be transparent to transmit light to the retina. Because of injury, infection or inflammation, an area of opacity may develop which can be seen with a penlight or ophthalmoscope. In rare instances, this opacity is congenital. In some, there is a family history of corneal growth disorders which may be progressive with age. Much more commonly, misuse of contact lenses may be a precipitating factor. Whichever, it is always potentially serious"
"in the eye (uveitis). The collagen fibres of the vitreous are held apart by electrical charges. With aging, these charges tend to reduce, and the fibres may clump together. Similarly, the gel may liquefy, a condition known as synaeresis, allowing cells and other organic clusters to float freely within the vitreous humour. These allow floaters which are perceived in the visual field as spots or fibrous strands. Floaters are generally harmless, but the sudden onset of recurring floaters may signify a posterior vitreous detachment or other diseases of the eye. Posterior vitreous detachment: Once liquid vitreous enters the sub-hyaloid space"
"small as and as large as have been observed. The cloudy outer edge of the eye is called the ""eyewall"". The eyewall typically expands outward with height, resembling an arena football stadium; this phenomenon is sometimes referred to as the ""stadium effect"". The eyewall is where the greatest wind speeds are found, air rises most rapidly, clouds reach to their highest altitude, and precipitation is the heaviest. The heaviest wind damage occurs where a tropical cyclone's eyewall passes over land. In a weaker storm, the eye may be obscured by the central dense overcast, which is the upper-level cirrus shield"
"Periorbital puffiness Periorbital puffiness, also known as ""puffy eyes"", or swelling around the eyes, is the appearance of swelling in the tissues around the eyes, called the orbits. It is almost exclusively caused by fluid buildup around the eyes, or periorbital edema. Minor puffiness usually detectable below the eyes only (although at times they could be present all around) is often called eye bags. Such transient puffiness is distinct from the age related and gradual increase in the size of the fat pad lying below the lower eyelids (suborbicularis oculi fat – ""SOOF"") which can also be colloquially referred to"
"on a daily basis. In children, early diagnosis and treatment of impaired visual system function is an important factor in ensuring that key social, academic and speech/language developmental milestones are met. Cataract is clouding of the lens, which in turn affects vision. Although it may be accompanied by yellowing, clouding and yellowing can occur separately. This is typically a result of ageing, disease, or drug use. Presbyopia is a visual condition that causes farsightedness. The eye's lens becomes too inflexible to accommodate to normal reading distance, focus tending to remain fixed at long distance. Glaucoma is a type of blindness"
"reduce eye puffiness and to maintain clear, moist skin. Periorbital puffiness Periorbital puffiness, also known as ""puffy eyes"", or swelling around the eyes, is the appearance of swelling in the tissues around the eyes, called the orbits. It is almost exclusively caused by fluid buildup around the eyes, or periorbital edema. Minor puffiness usually detectable below the eyes only (although at times they could be present all around) is often called eye bags. Such transient puffiness is distinct from the age related and gradual increase in the size of the fat pad lying below the lower eyelids (suborbicularis oculi fat"
"and involves the central or 'nuclear' part of the lens. This eventually becomes hard, or 'sclerotic', due to condensation on the lens nucleus and the deposition of brown pigment within the lens. In its advanced stages it is called a brunescent cataract. In early stages, an increase in sclerosis cause an increase in refractive index of the lens. This causes a myopic shift (lenticular shift) that decreases hyperopia and enables presbyopic patients to see at near without reading glasses. This is only tempororary and is called second sight. Cortical cataracts are due to the lens cortex (outer layer) becoming opaque."
"the geometric center of the storm. The eye may be clear or have spotty low clouds (a ""clear eye""), it may be filled with low- and mid-level clouds (a ""filled eye""), or it may be obscured by the central dense overcast. There is, however, very little wind and rain, especially near the center. This is in stark contrast to conditions in the eyewall, which contains the storm's strongest winds. Due to the mechanics of a tropical cyclone, the eye and the air directly above it are warmer than their surroundings. While normally quite symmetric, eyes can be oblong and irregular,"
"the eyeball, in whichever way the eyeball is oriented; the supine position (looking up or lying back) tends to concentrate them near the fovea, which is the center of gaze, while the textureless and evenly lit sky forms an ideal background against which to view them. The brightness of the daytime sky also causes the eyes' pupils to contract, reducing the aperture, which makes floaters less blurry and easier to see. Floaters present at birth usually remain lifelong, while those that appear later may disappear within weeks or months. They are not uncommon, and do not cause serious problems for"
"due to the effects of localized processes, such as thunderstorm activity and horizontal flow instabilities. In the vertical direction, winds are strongest near the surface and decay with height within the troposphere. At the center of a mature tropical cyclone, air sinks rather than rises. For a sufficiently strong storm, air may sink over a layer deep enough to suppress cloud formation, thereby creating a clear ""eye"". Weather in the eye is normally calm and free of clouds, although the sea may be extremely violent. The eye is normally circular in shape, and is typically in diameter, though eyes as"
"Keratoconus Keratoconus (KC) is a disorder of the eye which results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea. While the cause is unknown, it is believed to occur due to a combination of genetic, environmental, and hormonal factors. About seven percent of those affected have a family history of the condition. Proposed environmental factors include rubbing the eyes and allergies. The underlying mechanism involves changes of the cornea"
"colours other than silver or blue, because of iridescence caused by the uniform size of the water droplets produced. Noctilucent clouds may be seen by observers at a latitude of 50° to 65°. They seldom occur at lower latitudes (although there have been sightings as far south as Paris, Utah, Italy, Turkey and Spain), and closer to the poles it does not get dark enough for the clouds to become visible. They occur during summer, from mid-May to mid-August in the northern hemisphere and between mid-November and mid-February in the southern hemisphere. They are very faint and tenuous, and may"
"epithelium to become elevated, which leads to corneal opacities. The corneal erosions may prompt attacks of redness and swelling in the eye (ocular hyperemia), eye pain, and photophobia. Significant vision loss may occur. Reis-Bücklers dystrophy is diagnosed by clinical history physical examination of the eye. Labs and imaging studies are not necessary. Treatment may include a complete or partial corneal transplant, or photorefractive keratectomy. Patients with Reis-Bücklers dystrophy develop a reticular pattern of cloudiness in the cornea. This cloudiness, or opacity, usually appears in both eyes (bilaterally) in the upper cornea by 4 or 5 years of age. The opacity"
"arid places. Disordered hyperuniformity Disordered hyperuniformity is a type of liquid which has crystal properties. It greatly suppresses variations in the density of particles, like a crystal, and the particles have the same physical properties in all directions at shorter distances, like a liquid. It was discovered in the eyes of chickens. This is thought to be the case because chicken eyes cannot support the ordered, complex system best for eyesight. This may eventually be used for self-organizing colloids or optics with the ability to transmit light with crystal efficiency while still retaining liquid flexibility. Unique optical properties have been"
"length of the liquid diverges). As the density fluctuations become of a size comparable to the wavelength of light, the light is scattered and causes the normally transparent liquid to appear cloudy. Tellingly, the opalescence does not diminish as one gets closer to the critical point, where the largest fluctuations can reach even centimetre proportions, confirming the physical relevance of smaller fluctuations. In 1908 the Polish physicist Marian Smoluchowski became the first to ascribe the phenomenon of critical opalescence to large density fluctuations. In 1910 Albert Einstein showed that the link between critical opalescence and Rayleigh scattering is quantitative ."
"edges or in semi-transparent clouds, while newly forming clouds produce the brightest and most colorful iridescence. When the particles in a thin cloud are very similar in size over a large extent, the iridescence takes on the structured form of a corona, a bright circular disk around the Sun or Moon surrounded by one or more colored rings. Cloud iridescence Cloud iridescence or irisation is a colorful optical phenomenon that occurs in a cloud and appears in the general proximity of the Sun or Moon. The colors resemble those seen in soap bubbles and oil on a water surface. It"
"They occur when changes in the fluid contained in the periphery of the lens causes fissuring. When these cataracts are viewed through an ophthalmoscope, or other magnification system, the appearance is similar to white spokes of a wheel. Symptoms often include problems with glare and light scatter at night. Posterior subcapsular cataracts are cloudy at the back of the lens adjacent to the capsule (or bag) in which the lens sits. Because light becomes more focused toward the back of the lens, they can cause disproportionate symptoms for their size. An immature cataract has some transparent protein, but with a"
"Lagophthalmos Lagophthalmos is the inability to close the eyelids completely. Blinking covers the eye with a thin layer of tear fluid, thereby promoting a moist environment necessary for the cells of the exterior part of the eye. The tears also flush out foreign bodies and wash them away. This is crucial to maintain lubrication and proper eye health. If this process is impaired, as in lagophthalmos, the eye can suffer abrasions and infections. Lagopthalmos leads to corneal drying and ulceration. Lagophthalmos can arise from a malfunction of the facial nerve. Lagopthalmos can also occur in comatose patients having a decrease"
"Reis–Bucklers corneal dystrophy Reis-Bücklers corneal dystrophy, also known as corneal dystrophy of Bowman layer, type I, is a rare, corneal dystrophy of unknown cause, in which the Bowman's layer of the cornea undergoes disintegration. The disorder is inherited in an autosomal dominant fashion, and is associated with mutations in the gene TGFB1. Reis-Bücklers dystrophy causes a cloudiness in the corneas of both eyes, which may occur as early as 1 year of age, but usually develops by 4 to 5 years of age. It is usually evident within the first decade of life. This cloudiness, or opacity, causes the corneal"
"in the 60s, was the character 'the man with no eyes' from the movie ""Cool Hand Luke"". Mirrored sunglasses Mirrored sunglasses are sunglasses with a reflective optical coating (called a mirror coating or flash coating) on the outside of the lenses to make them appear like small mirrors. The lenses typically give the wearer's vision a brown or grey tint. The mirror coating decreases the amount of light passing through the tinted lens by a further 10–60%, making it especially useful for conditions of sand, water, snow, and higher altitudes. Mirrored sunglasses are one-way mirrors. The color of the mirror"
"Dry eye syndrome Dry eye syndrome (DES), also known as keratoconjunctivitis sicca (KCS), is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge, and easily fatigued eyes. Blurred vision may also occur. The symptoms can range from mild and occasional to severe and continuous. Scarring of the cornea may occur in some cases without treatment. Dry eye occurs when either the eye does not produce enough tears or when the tears evaporate too quickly. This can result from contact lens use, meibomian gland dysfunction, allergies, pregnancy, Sjögren's syndrome, vitamin A deficiency, LASIK surgery, and certain medications"
"Cataract A cataract is a clouding of the lens in the eye which leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. Cataracts cause half of all cases of blindness and 33% of visual impairment worldwide. Cataracts are most commonly due to aging but may also occur"
"such as the Amazon Rainforest and some others are almost always clear such as the Sahara Desert. Cloud cover Cloud cover (also known as cloudiness, cloudage, or cloud amount) refers to the fraction of the sky obscured by clouds when observed from a particular location. Okta is the usual unit of measurement of the cloud cover. The cloud cover is correlated to the sunshine duration as the least cloudy locales are the sunniest ones while the cloudiest areas are the least sunny places. The global cloud cover averages around 0.68 when analyzing clouds with optical depth larger than 0.1. This"
"fact, visible only because they do not remain perfectly fixed within the eye. Although the blood vessels of the eye also obstruct light, they are invisible under normal circumstances because they are fixed in location relative to the retina, and the brain ""tunes out"" stabilized images due to neural adaptation. This stabilization is often interrupted by floaters, especially when they tend to remain visible. Floaters are particularly noticeable when looking at a blank surface or an open monochromatic space, such as blue sky. Despite the name ""floaters"", many of these specks have a tendency to sink toward the bottom of"
"Sclerocornea Sclerocornea is a congenital anomaly of the eye in which the cornea blends with sclera, having no clear-cut boundary. The extent of the resulting opacity varies from peripheral to total (""sclerocornea totalis""). The severe form is thought to be inherited in an autosomal recessive manner, but there may be another, milder form that is expressed in a dominant fashion. In some cases the patients also have abnormalities beyond the eye (systemic), such as limb deformities and craniofacial and genitourinary defects. According to one tissue analysis performed after corneal transplantation, the sulfation pattern of keratan sulfate proteoglycans in the affected"
"was to remove clouded vitreous humor—usually containing blood. The success of these first procedures led to the development of techniques and instruments to remove clouding and also to peel scar tissue off the light sensitive lining of the eye—the retina—membranectomy, to provide space for materials injected in the eye to reattach the retina such as gases or liquid silicone, and to increase the efficacy of other surgical steps such as scleral buckle. The development of new instruments and surgical strategies through the 1970s and 1980s was spearheaded by surgeon/engineer Steve Charles, M.D. More recent advances have included smaller and more"
"pathogenesis is unknown. The condition is symptomless and untreatable.It appears as a beautiful shower of golden rain in ophthalmoscopic examination. Synchysis scintillans Synchysis scintillans is a degenerative condition of the eye resulting in liquefied vitreous humor and the accumulation of cholesterol crystals within the vitreous. It is also known as cholesterolosis bulbi. The vitreous liquifies in a process known as syneresis. Synchysis scintillans appears as small white floaters that freely move in the posterior part of the eye, giving a snow globe effect. It is most commonly seen in eyes that have suffered from a degenerative disease and are end-stage."
"Metamorphopsia Metamorphopsia is a type of distorted vision in which a grid of straight lines appears wavy and parts of the grid may appear blank. People can first notice they suffer with the condition when looking at mini-blinds in their home. It is mainly associated with macular degeneration, particularly age-related macular degeneration with choroidal neovascularization. Other conditions that can present with complaints of metamorphopsia include pathological myopia, presumed ocular histoplasmosis syndrome, choroidal rupture and multifocal choroiditis. Dry (nonexudative, > 80%)—deposition of yellowish extracellular material in and between bruch membrane and retinal pigment epithelium (“drusen”) with gradual loss in vision. Wet"
"as the ""aquula"" (Latin, ""a little stream"", dim. of ""aqua"", ""water"") or ""crystalline lens"". The lens is part of the anterior segment of the human eye. In front of the lens is the iris, which regulates the amount of light entering into the eye. The lens is suspended in place by the suspensory ligament of the lens, a ring of fibrous tissue that attaches to the lens at its equator and connects it to the ciliary body. Posterior to the lens is the vitreous body, which, along with the aqueous humor on the anterior surface, bathes the lens. The lens"