Congenital cataracts refers to a lens opacity present at birth. Congenital cataracts cover a broad spectrum of severity: whereas some lens opacities do not progress and are visually insignificant, others can produce profound visual impairment.

Congenital cataracts may be unilateral or bilateral. They can be classified by morphology, presumed or defined genetic cause, presence of specific metabolic disorders, or associated ocular anomalies or systemic findings.

Congenital cataracts occur in a variety of morphologic configurations, including lamellar, polar, sutural, coronary, cerulean, nuclear, capsular, complete, membranous.

Seeing rainbows around lights, especially at night, usually indicates swelling of the cornea. This may occur from a variety of causes which are discussed under Corneal Edema. Cataract can sometimes cause this also.

Colour vision is perceived mainly by the macula, which is the central vision portion of the retina. Thus any disorder affecting the macula may cause a disturbance in color vision. However, about 8% of males and 0.5% of females have some version of "colour blindness" from birth. Usually this is a genetically inherited trait, and is of the "red-green confusion" variety. The reds, browns, olives, and gold may be confused. Purple may be confused with blue, and pastel pinks, oranges, yellows, and greens look similar. Usually both eyes are affected equally.

There are many obscure macular retinal disorders that can lead to a loss of colour vision, and many of these syndromes are inherited as well. There may also be a problem with a generalized loss of vision with these problems as well. Other retinal problems can lead to a temporary disturbance of colour vision, such as Central serous chorioretinopathy, Macular Edema of different causes, and Macular Degeneration.

Certain types of cataract can gradually affect the colour vision, but this is usually not noticed until one cataract is removed. The cataract seems to filter out the colour blue, and everything seems more blue after cataract extraction. Optic nerve disorders such as Optic Neuritis can greatly affect colour vision, with colours seeming washed out during or after an episode.

The effects a coloboma has on the vision can be mild or more severe depending on the size and location of the gap. If, for example, only a small part of the iris is missing, vision may be normal, whereas if a large part of the retina or optic nerve is missing, vision may be poor and a large part of the visual field may be missing. This is more likely to cause problems with mobility if the lower visual field is absent. Other conditions can be associated with a coloboma. Sometimes, the eye may be reduced in size, a condition called microphthalmia. Glaucoma, nystagmus, scotoma, or strabismus may also occur.

Signs and symptoms vary depending on the type of cataract, though considerable overlap occurs. People with nuclear sclerotic or brunescent cataracts often notice a reduction of vision. Those with posterior subcapsular cataracts usually complain of glare as their major symptom.

The severity of cataract formation, assuming no other eye disease is present, is judged primarily by a visual acuity test. The appropriateness of surgery depends on a patient's particular functional and visual needs and other risk factors, all of which may vary widely.

Migraine headaches may be preceded by a visual "aura", lasting for 20 to 30 minutes, and then proceeding to the headache. Some people, however, experience the aura but do not have a headache. This visual aura can be very dramatic. Classically, a small blind spot appears in the central vision with a shimmering, zig-zag light inside of it. This enlarges, and moves to one side or the other of the vision, over a 20 to 30 minute period. When it is large, this crescent shaped blind spot containing this brightly flashing light can be difficult to ignore, and some people fear that they are having a stroke. In reality, it is generally a harmless phenomenon, except in people who subsequently get the headache of migraine. Since migraine originates in the brain, the visual effect typically involves the same side of vision in each eye, although it may seem more prominent in one eye or the other.

Some people get different variations of this phenomenon, with the central vision being involved, or with the visual effect similar to "heat rising off of a car". Some people describe a "kaleidoscope" effect, with pieces of the vision being missing. All of these variations are consistent with ophthalmic migraine.

With anterior lens luxation, the lens pushes into the iris or actually enters the anterior chamber of the eye. This can cause glaucoma, uveitis, or damage to the cornea. Uveitis (inflammation of the eye) causes the pupil to constrict (miosis) and trap the lens in the anterior chamber, leading to an obstruction of outflow of aqueous humour and subsequent increase in ocular pressure (glaucoma). Better prognosis is valued in lens replacement surgery (retained vision and normal intraocular pressure) when it is performed before the onset of secondary glaucoma. Glaucoma secondary to anterior lens luxation is less common in cats than dogs due to their naturally deeper anterior chamber and the liquification of the vitreous humour secondary to chronic inflammation. Anterior lens luxation is considered to be an ophthalmological emergency.

Lens subluxation is also seen in dogs and is characterized by a partial displacement of the lens. It can be recognized by trembling of the iris (iridodonesis) or lens (phacodonesis) and the presence of an aphakic crescent (an area of the pupil where the lens is absent). Other signs of lens subluxation include mild conjunctival redness, vitreous humour degeneration, prolapse of the vitreous into the anterior chamber, and an increase or decrease of anterior chamber depth. Removal of the lens before it completely luxates into the anterior chamber may prevent secondary glaucoma. A nonsurgical alternative involves the use of a miotic to constrict the pupil and prevent the lens from luxating into the anterior chamber.

A rhegmatogenous retinal detachment is commonly preceded by a posterior vitreous detachment which gives rise to these symptoms:

- flashes of light (photopsia) – very brief in the extreme peripheral (outside of center) part of vision

- a sudden dramatic increase in the number of floaters

- a ring of floaters or hairs just to the temporal (skull) side of the central vision

Although most posterior vitreous detachments do not progress to retinal detachments, those that do produce the following symptoms:

- a dense shadow that starts in the peripheral vision and slowly progresses towards the central vision

- the impression that a veil or curtain was drawn over the field of vision

- straight lines (scale, edge of the wall, road, etc.) that suddenly appear curved (positive Amsler grid test)

- central visual loss

In the event of an appearance of sudden flashes of light or floaters, an eye doctor needs to be consulted immediately. A shower of floaters or any loss of vision, too, is a medical emergency.

Other ocular malformations that include coloboma or are related to it:

- CHARGE syndrome, a term that came into use as an acronym for the set of unusual congenital features seen in a number of newborn children. The letters stand for: coloboma of the eye, heart defects, atresia of the nasal choanae, retardation of growth and/or development, genital and/or urinary abnormalities, and ear abnormalities and deafness. Although these features are no longer used in making a diagnosis, the name has remained.

- Cat eye syndrome, caused by the short arm (p) and a small section of the long arm (q) of human chromosome 22 being present three (trisomic) or four times (tetrasomic) instead of the usual two times. The term "cat eye" was coined because of the particular appearance of the vertical colobomas in the eyes of some patients.

- Patau syndrome (trisomy 13), a chromosomal abnormality that can cause a number of deformities, some of which include structural eye defects, including microphthalmia, Peters anomaly, cataract, iris and/or fundus coloboma, retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia.

- Treacher Collins syndrome, autosomal dominant syndrome caused by mutation of "TCOF1". Coloboma is part of a set of characteristic facies that features craniofacial malformations, such as downslanting eyes, ear anomalies, or hypoplasia of zygomatic bone and jaw (micrognathia).

Open-angle glaucoma is painless and does not have acute attacks, thus the lack of clear symptoms make screening via regular eye check-ups important. The only signs are gradually progressive visual field loss, and optic nerve changes (increased cup-to-disc ratio on fundoscopic examination).

About 10% of people with closed angles present with acute angle closure characterized by sudden ocular pain, seeing halos around lights, red eye, very high intraocular pressure (>30 mmHg), nausea and vomiting, suddenly decreased vision, and a fixed, mid-dilated pupil. It is also associated with an oval pupil in some cases. Acute angle closure is an emergency.

Opaque specks may occur in the lens in glaucoma, known as glaukomflecken.

Refractive errors such as hyperopia and Anisometropia may be associated abnormalities found in patients with vertical strabismus.

The vertical miscoordination between the two eyes may lead to

- Strabismic amblyopia, (due to deprivation / suppression of the deviating eye)

- cosmetic defect (most noticed by parents of a young child and in photographs)

- Face turn, depending on presence of binocular vision in a particular gaze

- diplopia or double vision - more seen in adults (maturity / plasticity of neural pathways) and suppression mechanisms of the brain in sorting out the images from the two eyes.

- cyclotropia, a cyclotorsional deviation of the eyes (rotation around the visual axis), particularly when the root cause is an oblique muscle paresis causing the hypertropia.

Hypertropia is a condition of misalignment of the eyes (strabismus), whereby the visual axis of one eye is higher than the fellow fixating eye.

Hypotropia is the similar condition, focus being on the eye with the visual axis lower than the fellow fixating eye.

Dissociated Vertical Deviation is a special type of hypertropia leading to slow upward drift of one or rarely both eyes, usually when the patient is inattentive.

There is another retinal disease in Briards known as hereditary retinal dysplasia. These dogs are night blind from birth, and day vision varies. Puppies affected often have nystagmus. It is also known as lipid retinopathy.

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 are the cause of half of blindness and 33% of visual impairment worldwide.

Cataracts are most commonly due to aging but may also occur 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. Either clumps of protein or yellow-brown pigment may be deposited in the lens reducing the 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 the only effective treatment. Surgery is needed only if the cataracts are causing problems and generally results in an improved quality of life. Cataract surgery is not readily available in many countries, which is especially true for women, those living in rural areas, and those who do not know how to read.

About 20 million people are blind due to cataracts. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. Blindness from cataracts occurs in about 10 to 40 per 100,000 children in the developing world, and 1 to 4 per 100,000 children in the developed world. Cataracts become more common with age. More than half the people in the United States had cataracts by the age of 80.

Secondary glaucoma (H40.3-H40.6)

- Inflammatory glaucoma

- Phacogenic glaucoma

- Glaucoma secondary to intraocular hemorrhage

- Traumatic glaucoma

- Neovascular glaucoma (see below for more details)

- Drug-induced glaucoma

- Glaucoma of miscellaneous origin

Neovascular glaucoma, an uncommon type of glaucoma, is difficult or nearly impossible to treat, and is often caused by proliferative diabetic retinopathy (PDR) or central retinal vein occlusion (CRVO). It may also be triggered by other conditions that result in ischemia of the retina or ciliary body. Individuals with poor blood flow to the eye are highly at risk for this condition.

Neovascular glaucoma results when new, abnormal vessels begin developing in the angle of the eye that begin blocking the drainage. Patients with such condition begin to rapidly lose their eyesight. Sometimes, the disease appears very rapidly, especially after cataract surgery procedures. A new treatment for this disease, as first reported by Kahook and colleagues, involves the use of a novel group of medications known as anti-VEGF agents. These injectable medications can lead to a dramatic decrease in new vessel formation and, if injected early enough in the disease process, may lead to normalization of intraocular pressure. Currently, there are no high-quality controlled trials demonstrating a beneficial effect of anti-VEGF treatments in lowering IOP in people with neovascular glaucoma.

Toxic glaucoma is open angle glaucoma with an unexplained significant rise of intraocular pressure following unknown pathogenesis. Intraocular pressure can sometimes reach . It characteristically manifests as ciliary body inflammation and massive trabecular oedema that sometimes extends to Schlemm's canal. This condition is differentiated from malignant glaucoma by the presence of a deep and clear anterior chamber and a lack of aqueous misdirection. Also, the corneal appearance is not as hazy. A reduction in visual acuity can occur followed neuroretinal breakdown.

Associated factors include inflammation, drugs, trauma and intraocular surgery, including cataract surgery and vitrectomy procedures. Gede Pardianto (2005) reported on four patients who had toxic glaucoma. One of them underwent phacoemulsification with small particle nucleus drops. Some cases can be resolved with some medication, vitrectomy procedures or trabeculectomy. Valving procedures can give some relief, but further research is required.

Zonular cataract and nystagmus, also referred as Nystagmus with congenital zonular cataract is a rare congenital disease associated with Nystagmus and zonular cataract of the eye.

It has been suggested that the disease follows a x-linked pattern of inheritance though studies done on this particular disease are few.

This condition is usually unilateral, and its symptoms vary from none to mild blurring and discomfort. Signs include diffuse iris atrophy and small white keratic precipitates (deposits on the inner surface of the cornea), cells presenting in the anterior chamber as well as the anterior vitreous. Glaucoma and cataract occur frequently.

Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's vitreous humour, which is normally transparent. At a young age, the vitreous is

transparent, but as one ages, imperfections gradually develop. The common type of floater, which is present in most persons' eyes, is due to degenerative changes of the vitreous humour. The perception of floaters is known as "myodesopsia", or less commonly as "myodaeopsia", "myiodeopsia", or "myiodesopsia". They are also called "Muscae volitantes" (Latin: "flying flies"), or "mouches volantes" (from the French). Floaters are visible because of the shadows they cast on the retina or refraction of the light that passes through them, and can appear alone or together with several others in one's visual field. They may appear as spots, threads, or fragments of cobwebs, which float slowly before the observer's eyes. As these objects exist within the eye itself, they are not optical illusions but are entoptic phenomena. They are not to be confused with visual snow, although these two conditions may co-exist.

Aphakia is the absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, far sightedness (hyperopia), and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.

Babies are rarely born with aphakia. Occurrence most often results from surgery to remove congenital cataract (clouding of the eye's lens, which can block light from entering the eye and focusing clearly). Congenital cataracts usually develop as a result of infection of the fetus or genetic reasons. It is often difficult to identify the exact cause of these cataracts, especially if only one eye is affected.

People with aphakia have relatively small pupils and their pupils dilate to a lesser degree.

When this occurs there is a characteristic pattern of symptoms:

- Flashes of light (photopsia)

- A sudden dramatic increase in the number of floaters

- A ring of floaters or hairs just to the temporal side of the central vision

As a posterior vitreous detachment proceeds, adherent vitreous membrane may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes that can look like a perfect circle.

If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Retinal vessels may tear in association with a retinal tear, or occasionally without the retina being torn.

Eye floaters are suspended in the vitreous humour, the thick fluid or gel that fills the eye. The vitreous humour, or vitreous body, is a jelly-like, transparent substance that fills a majority of the eye. It lies within the vitreous chamber behind the lens, and is one of the four optical components of the eye. Thus, floaters follow the rapid motions of the eye, while drifting slowly within the fluid. When they are first noticed, the natural reaction is to attempt to look directly at them. However, attempting to shift one's gaze toward them can be difficult as floaters follow the motion of the eye, remaining to the side of the direction of gaze. Floaters are, in 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 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 most persons; they represent one of the most common presentations to hospital eye services. A survey of optometrists in 2002 suggested that an average of 14 patients per month per optometrist presented with symptoms of floaters in the UK. However, floaters are more than a nuisance and a distraction to those with severe cases, especially if the spots seem to constantly drift through the field of vision. The shapes are shadows projected onto the retina by tiny structures of protein or other cell debris discarded over the years and trapped in the vitreous humour. Floaters can even be seen when the eyes are closed on especially bright days, when sufficient light penetrates the eyelids to cast the shadows. It is not, however, only elderly persons who are troubled by floaters; they can also become a problem to younger people, especially if they are myopic. They are also common after cataract operations or after trauma.

Floaters are able to catch and refract light in ways that somewhat blur vision temporarily until the floater moves to a different area. Often they trick persons who are troubled by floaters into thinking they see something out of the corner of their eye that really is not there. Most persons come to terms with the problem, after a time, and learn to ignore their floaters. For persons with severe floaters it is nearly impossible to completely ignore the large masses that constantly stay within almost direct view.

Floaters have been reported in patients as young as 3. Floaters in teenage patients and young adults are usually harder to treat. For persons in this age group, the floater that is seen usually looks like a kind of translucent worm/web/cell. Very little is known about this region, and it only becomes distinct after the vitreous humour detaches from the retina at later stages of life. Due to their microscopic size they cannot be seen by doctors. They only appear as big as they do because of their proximity to the retina. This type of floater is still described occasionally in people in their 30s and very rarely occurs in people in their 40s.

Leukocoria (also leukokoria or white pupillary reflex) is an abnormal white reflection from the retina of the eye. Leukocoria resembles eyeshine, but leukocoria can occur in humans and other animals that lack eyeshine because their retina lacks a "tapetum lucidum".

Leukocoria is a medical sign for a number of conditions, including Coats disease, congenital cataract, corneal scarring, melanoma of the ciliary body, Norrie disease, ocular toxocariasis, persistence of the tunica vasculosa lentis (PFV/PHPV), retinoblastoma, and retrolental fibroplasia.

Because of the potentially life-threatening nature of retinoblastoma, a cancer, that condition is usually considered in the evaluation of leukocoria. In some rare cases (1%) the leukocoria is caused by Coats' disease (leaking retinal vessels).

Acorea or fibrous occlusion of the pupil, microphthalmia and cataracts are present in both eyes. Microcornea and iridocorneal dysgenesis also occur. The retina and optic disc are normal.