Squamous cell carcinoma of eye tissues is one of the most frequent neoplasms of cattle.

Conjunctival Squamous Cell Carcinoma (Conjunctival SCC) and corneal intraepithelial neoplasia comprise what are called Ocular Surface Squamous Cell Neoplasias. SCC is the most common malignancy of the conjunctiva in the US, with a yearly incidence of 1-2.8 per 100,000. Risk factors for the disease are exposure to sun (specifically occupational), exposure to UVB, and light-colored skin. Other risk factors include radiation, smoking, HPV, arsenic, and exposure to polycyclic hydrocarbons.

Conjunctival SCC is often asymptomatic at first, but it can present with the presence of a growth, red eye, pain, itching, burning, tearing, sensitivity to light, double vision, and decreased vision.

Spread of conjunctival SCC can occur in 1-21% of cases, with the first site of spread being the regional lymph nodes. Mortality for conjunctival SCC ranges from 0-8%.

Diagnosis is often made by biopsy, as well as CT (in the case of invasive SCC).

Treatment of Conjunctival SCC is usually surgical excision followed by cryotherapy. After this procedure, Conjunctival SCC can recur 8-40% of the time. Radiation treatment, topical Mitomycin C, and removal of the contents of the orbit, or exenteration, are other methods of treatment. Close follow-up is recommended, because the average time to recurrence is 8–22 months.

Ciliary Body Melanoma is a type of cancer arising from the coloured part (uvea) of the eye.

About 12% of uveal melanoma arise from the ciliary body.

It occurs most commonly in the sixth decade.

- External signs include dilated episcleral blood vessels ("sentinel vessels"). Extraocular erosion may produce a dark mass beneath the conjunctiva.

- Pressure on the lens by the enlarging tumor can cause astigmatism, sublaxtion of the lens and formation of a localised lens opacity.

- The tumor can erode forward through the iris root and mimic an iris melanoma.

- Retinal detachment can be rarely caused by posterior extension of the tumor.

- Anterior uveitis is an uncommon presentation and occurs due to tumor necrosis.

- Cirumferentially growing tumors carry a bad prognosis as they are diagnosed late.

- At times the tumor is detected as an incidental finding during routine examination.

The tumour is usually diagnosed by clinical examination with a slit-lamp utilising a triple mirror contact lens. Ultrasonography and fine needle aspiration biopsy (FNAB) are also sometimes helpful in confirming the diagnosis.

Hereditary benign intraepithelial dyskeratosis is a rare autosomal dominant disease of the conjunctiva and the oral mucosa caused by a duplication of chromosome 4q35. In the mouth it appears similar to white sponge nevus, with painless, diffuse, folded and spongy white plaques. In the eye it appears as gelatinous plaques on bulbar perilimbal conjunctiva.

Pyogenic granuloma (also known as a "eruptive hemangioma", "granulation tissue-type hemangioma", "granuloma gravidarum", "lobular capillary hemangioma", "pregnancy tumor", and "tumor of pregnancy") is a vascular lesion that occurs on both mucosa and skin, and appears as an overgrowth of tissue due to irritation, physical trauma, or hormonal factors. It is often found to involve the gums, the skin and nasal septum, and has also been found far from the head such as in the thigh.

Juvenile xanthogranuloma (JXG) is a form of histiocytosis, classified as "non-Langerhans cell histiocytosis", or more specifically, "type 2".

It is a rare skin disorder that primarily affects children under one year of age but can also be found in older children and adults. It was first described in 1905 by Adamson. In 5% to 17% of people, the disorder is present at birth, but the median age of onset is two years. JXG is a benign idiopathic cutaneous granulomatous tumor and the most common form of non-Langerhans cell histiocytosis (non-LHC). The lesions appear as orange-red macules or papules and are usually located on the face, neck, and upper trunk. They may also appear at the groin, scrotum, penis, clitoris, toenail, palms, soles, lips, lungs, bone, heart, and gastrointestinal tract more rarely. JXG usually manifests with multiple lesions on the head and neck in cases with children under six months of age. The condition usually resolves spontaneously over one to five years. A biopsy of the lesion is critical to confirm the diagnosis.

Ocular JXG manifests in up to 10% of people with JXG and may affect their vision. The presence of JXG in the eye can cause spontaneous hyphema, secondary glaucoma or even blindness. It is most often seen in the iris but may be found on the eyelid, corneoscleral limbus, conjunctiva, orbit, retina, choroid, disc, or optic nerve. Of patients with ocular JXG, 92% are younger than the age of two. Although cutaneous JXG usually disappear spontaneously, ocular lesions rarely improve spontaneously and require treatment. Treatments that have been used include surgical excision, intralesional steroid injection, cryotherapy, and low dose radiotherapy. In the case of a resistant or reoccurring lesion, chemotherapy has been used as a treatment. Ocular JXG is usually unilateral and presents with a tumor, a red eye with signs of uveitis, unilateral glaucoma, spontaneous hyphema or heterochromia iridis. Diagnosing and treating the patient as early as possible contributes to the most positive visual outcome.

Histiocytic disorders like JXG are identified by the cells that make them up. Immunohistochemical analysis is used to discern the immunoreactivity to certain antibodies in these analyses. JXG is a non-LHC disorder which is a varied group of disorders defined by the accumulation of histiocytes that do not meet criteria to be diagnosed as Langerhans cells. JXG is not metastatic and may be present with lipid deposits. JXG is often accompanied with other disorders such as neurofibromatosis type one and juvenile chronic myelogenous leukemia. Juvenile variety xantogranuloma can be distinguished from xanthoma by the spread of the lesion and the lack of lipid abnormalities. Other similar diagnoses include molluscum contagiosum, hemangioma and neurofibroma.

The appearance of pyogenic granuloma is usually a color ranging from red/pink to purple, and can be smooth or lobulated. Younger lesions are more likely to be red because of the high number of blood vessels. Older lesions begin to change into a pink color. Size commonly ranges from a few millimeters to centimeters, though smaller or larger lesions may occur. A pyogenic granuloma can be painful, especially if located in an area of the body where it is constantly disturbed. Pyogenic granulomas can grow rapidly and will often bleed profusely with little or no trauma. They may exude an oil like substance, causing the surface to be damp. This is especially true if the granuloma is located on the scalp.

Pyogenic granulomas may be seen at any age, and are more common in females than males. In pregnant women, lesions may occur in the first trimester with an increasing incidence up until the seventh month, and are often seen on the gums. Epulis granulomatosum is a variant of pyogenic granuloma that forms only on gingiva, and is often seen forming in a recent extraction socket. Pyogenic granulomas appear on the gingiva in 75% of cases, more often in the maxillary than mandibular jaw. Anterior areas are more often affected than posterior areas. It can also be found on the lips, tongue, and inner cheek. Poor oral hygiene or trauma are usually precipitating factors.

One study has suggested a correlation between pyogenic granulomas and Bartonella seropositivity. However, this association has been questioned by others. The microscopic appearance of a pyogenic granuloma consists of highly vascular granulation tissue. Inflammation is present. The lesion may have a fibrous character if it is older, and the surface may have ulcerations. Pyogenic granulomas rarely occur in the conjunctiva, cornea or connective tissue of the eye following minor local trauma. Grossly these mass lesions resemble those occurring at more common sites. The relationship of these lesion to lobular capillary hemangiomas of skin and oropharyngeal mucosa commonly referred to as pyogenic granuloma is uncertain.

Cardiac myxomas can be difficult to manage surgically because of recurrence within the heart, often far away from the site of the initial tumor.

The exact cause is unknown, but it is associated with excessive exposure to wind, sunlight, or sand. Therefore, it is more likely to occur in populations that inhabit the areas near the equator, as well as windy locations. In addition, pterygia are twice as likely to occur in men than women.

A pterygium is a pinkish, triangular tissue growth on the cornea of the eye. It typically starts on the cornea near the nose. It may slowly grow but rarely grows so large that the pupil is covered. Often both eyes are involved.

The cause is unclear. It appears to be partly related to long term exposure to UV light and dust. Genetic factors also appear to be involved. It is a benign growth. Other conditions that can look similar include a pinguecula, tumor, or Terrien's marginal corneal degeneration.

Prevention may include wearing sunglasses and a hat if in an area with strong sunlight. Among those with the condition, an eye lubricant can help with symptoms. Surgical removal is typically only recommended if the ability to see is affected. Following surgery a pterygium may recur in around half of cases.

The frequency of the condition varies from 1% to 33% in various regions of the world. It occurs more commonly among males than females and in people who live closer to the equator. The condition becomes more common with age. The condition has been described since at least 1000 BC.

Actinic elastosis, also known as solar elastosis, is an accumulation of abnormal elastin (elastic tissue) in the dermis of the skin, or in the conjunctiva of the eye, which occurs as a result of the cumulative effects of prolonged and excessive sun exposure, a process known as photoaging.

A pinguecula is one of the differential diagnoses for a limbal nodule. It may have an increased prevalence in Gaucher's disease.

Primary lymphedema is a form of lymphedema which is not directly attributable to another medical condition.

It can be divided into three forms, depending upon age of onset: congenital lymphedema, lymphedema praecox, and lymphedema tarda.

Congenital lymphedema presents at birth. Lymphedema praecox presents from ages 1 to 35. This type of lymphedema accounts for 77–94% of all cases of primary lymphedema. Lymphedema tarda presents after age 35. This type of lymphedema usually develops as a result of a developmental abnormality being precipitated by some insult such as trauma, illness, or physical immobility. Compared to secondary lymphedema, primary lymphedema is more likely to involve the face, conjunctiva, and genitalia in association with any limbs involved.

It can be familial.

An ectopic cilia is a special type of distichia. It is usually found in younger dogs. Commonly affected breeds include Poodles, Golden Retrievers, and Shih Tzus. The eyelash exits through the conjunctiva of the eyelid facing toward the eye, usually at the middle of the upper eyelid. It can cause intense pain and corneal ulcers. Treatment is surgery or cryotherapy.

Bitot's spots are the buildup of keratin located superficially in the conjunctiva, which are oval, triangular or irregular in shape. These spots are a sign of vitamin A deficiency and are associated with conjunctival xerosis. In 1863, Pierre Bitot (1822-1888), a French physician, first described these spots.

In ancient Egypt, this was treated with animal liver, which is where vitamin A is stored.

Histopathological findings from affected humans indicate that wound healing is impaired due to a deficiency in plasmin-mediated extracellular fibrinolysis. Episodes may be triggered by minor trauma, eye surgery, or by systemic events such as infections or antifibrinolytic therapy. Histology shows amorphous subepithelial deposits of eosinophilic material consisting predominantly of fibrin.

Actinic elastosis usually appears as thickened, dry, wrinkled skin. Several clinical variants have been recorded. One of the most readily identifiable is the thickened, deeply fissured skin seen on the back of the chronically sun-exposed neck, known as cutis rhomboidalis nuchae. These features are a part of the constellation of changes that are seen in photoaged skin.

Carney complex and its subsets LAMB syndrome and NAME syndrome are autosomal dominant conditions comprising myxomas of the heart and skin, hyperpigmentation of the skin (lentiginosis), and endocrine overactivity. It is distinct from Carney's triad. Approximately 7% of all cardiac myxomas are associated with Carney complex.

A pinguecula is a common type of conjunctival degeneration in the eye.

Ligneous conjunctivitis is a rare form of chronic conjunctivitis characterized by recurrent, fibrin-rich pseudomembranous lesions of wood-like consistency that develop mainly on the underside of the eyelid (tarsal conjunctiva). It is generally a systemic disease which may involve the periodontal tissue, the upper and lower respiratory tract, kidneys, middle ear, and female genitalia. It can be sight-threatening, and death can occasionally occur from pulmonary involvement.

It has been speculated that ligneous conjunctivitis may be a manifestation of IgG4-related disease (IgG4-RD) involving the conjunctiva.

Chronic conjunctivitis (e.g. trachoma) and aging factor are two causes of conjunctival concretion, which will make the conjunctiva cellular degeneration to produce an epithelial inclusion cyst, filled with epithelial cells and keratin debris. After calcification, the conjunctival cyst hardens and forms a conjunctival concretion. Congenital conjunctival concretion condition is also more common.

Concretion in the palpebral conjunctiva, is called conjunctival concretion, that is a (or a cluster) small, hard, yellowish-white calcified matter, superficially buried beneath the palpebral conjunctiva. Most of concretions in the eye form in the palpebral conjunctiva, which is a clear membrane to surround the inside of the eyelid. Less can be located in the cornea and retina.

A distichia is an eyelash that arises from an abnormal spot on the eyelid. This abnormality, attributed to a genetic mutation, is known to affect dogs and humans. Distichiae (the abnormal eyelash) usually exit from the duct of the meibomian gland at the eyelid margin. They are usually multiple and sometimes more than one arises from a duct. They can affect either the upper or lower eyelid and are usually bilateral. The lower eyelids of dogs usually have no eyelashes.

Distichiae usually cause no symptoms because the lashes are soft, but they can irritate the eye and cause tearing, squinting, inflammation, and corneal ulcers and scarring. Treatment options include manual removal, electrolysis, electrocautery, cryotherapy, and surgery.

Episcleritis is a common disease, and its exact prevalence and incidence are unknown. It typically affects young adults, and may be more common in women.