Ectropion in dogs usually involves the lower eyelid. Often the condition has no symptoms, but tearing and conjunctivitis may be seen. Breeds associated with ectropion include the Cocker Spaniel, the Saint Bernard, the Bloodhound, the Clumber Spaniel, and the Basset Hound. It can also result from trauma or nerve damage. Treatment (surgery) is recommended only if there is chronic conjunctivitis or if there is corneal damage. A small part of the affected lid is removed and then the lid is sewn back together.

Epiphora is an overflow of tears onto the face. A clinical sign or condition that constitutes insufficient tear film drainage from the eyes in that tears will drain down the face rather than through the nasolacrimal system.

Ectropion is a medical condition in which the lower eyelid turns outwards. It is one of the notable aspects of newborns exhibiting congenital Harlequin-type ichthyosis, but ectropion can occur due to any weakening of tissue of the lower eyelid. The condition can be repaired surgically. Ectropion is also found in dogs as a genetic disorder in certain breeds.

Causes of epiphora are any that cause either overproduction of tears or decreased drainage of tears, resulting in tearing onto the cheek. This can be due to ocular irritation and inflammation (including trichiasis and entropion) or an obstructed tear outflow tract which is divided according to its anatomical location (i.e. ectropion, punctal, canalicular or nasolacrimal duct obstruction). The latter is often due to aging (a spontaneous process), conjunctivochalasis, infection (i.e. dacryocystitis), rhinitis, and in neonates or infants, failure of the nasolacrimal duct to open. Another cause could be poor reconstruction of the nasolacrimal duct system after trauma to the area. Cause of trauma could be facial fractures (including nasoethmoid fractures or maxillary Le Fort fractures), and soft tissue trauma involving the nose and/or the eyelid.

This condition is often frustrating or irritating. A systematic review studying the usage of punctal plugs for treatment of dry eye reported a few cases of epiphora among participants.

In addition to small palpebral fissures, features include epicanthus inversus (fold curving in the mediolateral direction, inferior to the inner canthus), low nasal bridge, ptosis of the eyelids and telecanthus.

Blepharophimosis syndrome is an autosomal dominant characterized by blepharophimosis (horizontal shortening of the palpebral fissures), ptosis (upper eyelid drooping, usually with the characteristics of congenital ptosis), epicanthus inversus (skin folds by the nasal bridge, more prominent lower than upper lid), and telecanthus (widening of the distance between the medial orbital walls). This syndrome is caused by mutations in the FOXL2 gene, either with premature ovarian failure (BPES type I) or without (BPES type II). It may also be associated with lop ears, ectropion, hypoplasia of superior orbital rims, and hypertelorism.

Blepharochalasis results from recurrent bouts of painless eyelid swelling, each lasting for several days. This is thought to be a form of localized angioedema, or rapid accumulation of fluid in the tissues. Recurrent episodes lead to thin and atrophic skin. Damage to the levator palpebrae superioris muscle causes ptosis, or drooping of the eyelid, when the muscle can no longer hold the eyelid up.

Dermatochalasis is sometimes confused with blepharochalasis, but these are two different conditions.

It is a characterized by a breakdown or damage of the epithelium of the cornea in a pinpoint pattern, which can be seen with examination with a slit-lamp. Patients may present with non-specific symptoms such as red eye, tearing, foreign body sensation, photophobia and burning.

Blepharitis is characterized by chronic inflammation of the eyelid, usually at the base of the eyelashes. Symptoms include inflammation, irritation, itchiness, a burning sensation, excessive tearing, and crusting and sticking of eyelids. Additional symptoms may include visual impairment such as photophobia and blurred vision. Symptoms are generally worse in the mornings and patients may experience exacerbation and several remissions if left untreated. It is typically caused by bacterial infection or blockage of the meibomian oil glands. Diseases and conditions that may lead to blepharitis include: rosacea, herpes simplex dermatitis, varicella-zoster dermatitis, molluscum contagiosum, allergic dermatitis, contact dermatitis, seborrheic dermatitis, staphylococcal dermatitis, demodicosis (Demodex), and parasitic infections ("e.g.", Demodex and Phthiriasis palpebrarum).

The parasite, "Demodex folliculorum" ("D. folliculorum"), causes blepharitis when the parasite is present in excessive numbers within the dermis of the eyelids. These parasites can live for approximately 15 days. The parasites (both adult and eggs) live on the hair follicle, inhabiting the sebaceous and apocrine gland of the human lid. Direct contact allows this pathogen to spread. Factors that allow this pathogen to multiply include hypervascular tissue, poor hygienic conditions, and immune deficiency. In treating Blepharitis caused by "D. folliculorum", mechanical cleaning and proper hygiene are important towards decreasing the parasites numbers.

Associated Symptoms:

- Watery eyes - due to excessive tearing.

- Red eyes - due to dilated blood vessels on the sclera.

- Swollen eyelids - due to inflammation.

- Crusting at the eyelid margins/base of the eyelashes/medial canthus, generally worse on waking - due to excessive bacterial buildup along the lid margins.

- Eyelid sticking - due to crusting along the eyelid margin.

- Eyelid itching - due to the irritation from inflammation and epidermis scaling of the eyelid.

- Flaking of skin on eyelids - due to tear film suppressed by clog meibomian glands.

- Gritty/burning sensation in the eye, or foreign-body sensation - due to crusting from bacteria and clogged oil glands

- Frequent blinking - due to impaired tear film from clogged oil glands unable to keep tears from evaporating.

- Light sensitivity/photophobia

- Misdirected eyelashes that grow abnormally - due to permanent damage to the eyelid margin

- Eyelash loss - due to excessive buildup of bacteria along the base of the eyelashes.

- Infection of the eyelash follicle/sebaceous gland (hordeolum)

- Debris in the tear film, seen under magnification (improved contrast with use of fluorescein drops)

Chronic blepharitis may result in damage of varying severity and, in the worst cases, may have a negative effect on vision. This can be resolved with a proper eyeglass prescription. Long-term untreated blepharitis can lead to eyelid scarring, excess tearing, difficulty wearing contact lenses, development of a stye (an infection near the base of the eyelashes, resulting in a painful lump on the edge of the eyelid) or a chalazion (a blockage/bacteria infection in a small oil glands at the margin of the eyelid, just behind the eyelashes, leading to a red, swollen eyelid), chronic pink eye (conjunctivitis), keratitis, and corneal ulcer or irritation. The lids may become red and may have ulcerate, non-healing areas that may lead to bleeding. Blepharitis can also cause blurred vision due to a poor tear film. Tears may be frothy or bubbly, which can contribute to mild scarring along the eyelids. Symptoms and signs of blepharitis are often erroneously ascribed by the patient as "recurrent conjunctivitis".

Staphylococcal blepharitis and Posterior blepharitis or "rosacea-associated" blepharitis Symptoms

Symptoms include a foreign body sensation, matting of the lashes, and burning. Collarette around eyelashes, a ring-like formation around the lash shaft, can be observed. Other symptoms include loss of eyelashes or broken eyelashes. The condition can sometimes lead to a chalazion or a stye. Chronic bacterial blepharitis may also lead to ectropion. Posterior blepharitis or "rosacea-associated" blepharitis is manifested by a broad spectrum of symptoms involving the lids including inflammation and plugging of the meibomian orifices and production of abnormal secretion upon pressure over the glands.

Punctate epithelial erosions is a pathology affecting the cornea. It is also known as punctate erosive keratopathy or superficial punctate keratitis.

Floppy eyelid syndrome is a disease whose most prominent features often include floppy upper eyelids that can be easily everted, as well as papillary conjunctivitis. It is often associated with patients with high body mass index and obstructive sleep apnea.

Floppy eyelid syndrome is thought to revolve around the upregulation of elastin-degrading enzymes, as well as mechanical factors. These can cause instability of the eyelid scaffold, resulting in the malposition of the eyelid.

Blepharitis ( ) is one of the most common ocular conditions characterized by inflammation, scaling, reddening, and crusting of the eyelid. This condition may also cause burning, itching, or a grainy sensation when introducing foreign objects or substances to the eye. Although blepharitis is not sight-threatening, it can lead to permanent alterations of the eyelid margin. The overall etiology is a result of bacteria and inflammation from congested meibomian oil glands at the base of each eyelash. Other conditions may give rise to blepharitis, whether they be infectious or noninfectious, including, but not limited to, bacterial infections or allergies.

Different variations of blepharitis can be classified as seborrheic, staphylococcal, mixed, posterior or meibomitis, or parasitic. In a survey of US ophthalmologists and optometrists, 37% to 47% of patients seen by those surveyed had signs of blepharitis, which can affect all ages and ethnic groups. One single-center study of 90 patients with chronic blepharitis found that the average age of patients was 50 years old.

Exophoria is particularly common in infancy and childhood, and increases with age.

Newborns with harlequin-type ichthyosis present with thick, fissured armor-plate hyperkeratosis. Sufferers feature severe cranial and facial deformities. The ears may be very poorly developed or absent entirely, as may the nose. The eyelids may be everted (ectropion), which leaves the eyes and the area around them very susceptible to infection. Babies with this condition often bleed during birth. The lips are pulled back by the dry skin (eclabium). Joints are sometimes lacking in movement, and may be below the normal size. Hypoplasia is sometimes found in the fingers. Polydactyly has also been found on occasion. In addition, the fish mouth appearance, mouth breathing, and xerostomia place affected individuals at extremely high risk for developing rampant dental decay.

Patients with this condition are extremely sensitive to changes in temperature due to their hard cracked skin, which prevents normal heat loss. Respiration is also restricted by the skin, which impedes the chest wall from expanding and drawing in enough air. This can lead to hypoventilation and respiratory failure. Patients are often dehydrated, as their plated skin is not well suited to retaining water.

Cervical ectropion can be associated with excessive but non-purulent vaginal discharge due to the increased surface area of columnar epithelium containing mucus-secreting glands. It may also give rise to post-coital bleeding, as fine blood vessels present within the columnar epithelium are easily traumatised.

Exophoria is a form of heterophoria in which there is a tendency of the eyes to deviate outward. During examination, when the eyes are dissociated, the visual axes will appear to diverge away from one another.

The axis deviation in exophoria is usually mild compared with that of exotropia.

In mechanical anisocoria, this is the result of damage to the iris dilator muscle, which may be caused by trauma, angle-closure glaucoma, surgery such as cataract removal, or uveitis (inflammation of the eye). Slit lamp examination is often used as a diagnostic aid: damage to the dilator muscle is indicated by anisocoria when light intensity is lowered.Anisocoria refers to a common eye condition in which the two pupils differ in size.

This type of failure of eruption takes place when the affected tooth is ankylosed to the bone around it. This is different than primary failure of eruption where the affected tooth/teeth were not ankylosed. In mechanical failure of eruption, affected tooth has partial or complete loss of PDL in a panoramic radiograph and teeth distal to affected tooth do not have this condition. On a percussion test, a tooth with mechanical failure of eruption will have a dull metallic sound.

Superior limbic keratoconjunctivitis is an ocular disease characterized by episodes of recurrent inflammation of the superior cornea and limbus, as well as of the superior tarsal and bulbar conjunctiva.

Even though the pathophysiology remains unclear, it is thought that mechanical trauma from tight upper lids or loose redundant conjunctiva could lead to the disruption of normal epithelium. This mechanical hypothesis is supported by the increased lid apposition of exophthalmic thyroid patients, who are known to have an increased incidence of superior limbic keratoconjunctivitis.

Patients present with red eye, burning, tearing, foreign body sensation, mild photophobia. Inflammation and thickening of the conjunctiva is observed, especially at the limbus.Lubrication is an effective treatment for this pathology.

There have been many syndromes which have been identified to be related to failure of eruption of teeth. These syndromes are Cleidocranial dyspalsia, Osteoporosis, Rutherford syndrome, GAPO syndrome and Osteoglophonic dysplasia.

Harlequin-type ichthyosis is a genetic disorder which results in thickened skin over nearly the entire body at birth. The skin forms large, diamond-shaped plates that are separated by deep cracks. They affect the shape of the eyelids, nose, mouth, and ears, and limit movement of the arms and legs. Restricted movement of the chest can lead to breathing difficulties. These plates fall off over weeks. Other complications can include premature birth, infection, problems with body temperature, and dehydration.

Harlequin-type ichthyosis is due to mutations of the "ABCA12" genes. It is inherited from a person's parents in an autosomal recessive manner. Diagnosis is often based on appearance at birth and confirmed by genetic testing. Before birth amniocentesis or ultrasound may support the diagnosis.

There is no cure. Early in life constant supportive care is typically required. Treatments may include moisturizing cream, antibiotics, etretinate, or retinoids. It affects about 1 per 300,000 births. Both sexes are affected equally commonly. Long term problems are common. Death in the first month is relatively common. The condition was first documented in 1750.

Anisocoria is a common condition, defined by a difference of 0.4 mm or more between the sizes of the pupils of the eyes.

Anisocoria has various causes:

- Physiological anisocoria: About 20% of normal people have a slight difference in pupil size which is known as physiological anisocoria. In this condition, the difference between pupils is usually less than 1 mm.

- Horner's syndrome

- Mechanical anisocoria: Occasionally previous trauma, eye surgery, or inflammation (uveitis, angle closure glaucoma) can lead to adhesions between the iris and the lens.

- Adie tonic pupil: Tonic pupil is usually an isolated benign entity, presenting in young women. It may be associated with loss of deep tendon reflex (Adie's syndrome). Tonic pupil is characterized by delayed dilation of iris especially after near stimulus, segmental iris constriction, and sensitivity of pupil to a weak solution of pilocarpine.

- Oculomotor nerve palsy: Ischemia, intracranial aneurysm, demyelinating diseases (e.g., multiple sclerosis), head trauma, and brain tumors are the most common causes of oculomotor nerve palsy in adults. In ischemic lesions of the oculomotor nerve, pupillary function is usually spared whereas in compressive lesions the pupil is involved.

- Pharmacological agents with anticholinergic or sympathomimetic properties will cause anisocoria, particularly if instilled in one eye. Some examples of pharmacological agents which may affect the pupils include pilocarpine, cocaine, tropicamide, MDMA, dextromethorphan, and ergolines. Alkaloids present in plants of the genera "Brugmansia" and "Datura", such as scopolamine, may also induce anisocoria.

- Migraines

Anisocoria is a condition characterized by an unequal size of the eyes' pupils. Affecting 20% of the population, it can be an entirely harmless condition or a symptom of more serious medical problems.

Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria.

Causes include:

- Refractive errors

- Divergence insufficiency

- Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.

Unlike esotropia, fusion is possible and therefore diplopia is uncommon.