Subepithelial mucinous corneal dystrophy (SMCD) is a rare form of corneal dystrophy. It was first described in 1993 by Feder et al. Anterior to Bowman layer, deposits of glycosaminoglycan were detected and identified as chondroitin-4-sulfate and dermatan sulfate.

Blepharochalasis is idiopathic in most cases, i.e., the cause is unknown. Systemic conditions linked to blepharochalasis are renal agenesis, vertebral abnormalities, and congenital heart disease.

The cause of the rare condition of tumoral calcinosis is not entirely understood. It is generally characterized by large, globular calcifications near joints.

It is encountered more commonly in younger rather than older individuals.

The majority of patients with neurocutaneous melanosis are asymptomatic and therefore have a good prognosis with few complications. Most are not diagnosed, so definitive data in not available. For symptomatic patients, the prognosis is far worse. In patients without the presence of melanoma, more than 50% die within 3 years of displaying symptoms. While those with malignancy have a mortality rate of 77% with most patients displaying symptoms before the age of 2.

The presence of a Dandy-Walker malformation along with neurocutaneous melanosis, as occurs in 10% of symptomatic patients, further deteriorates prognosis. The median survival time for these patients is 6.5 months after becoming symptomatic.

The cornea, an avascular tissue, is among the most densely innervated structures of the human body. Corneal nerves are responsible for maintaining the anatomical and functional integrity of the cornea, conveying tactile, temperature and pain sensations, playing a role in the blink reflex, in wound healing and in the production and secretion of tears.

Most corneal nerve fibres are sensory in origin and are derived from the ophthalmic branch of the trigeminal nerve. Congenital or acquired ocular and systemic diseases can determine a lesion at different levels of the trigeminal nerve, which can lead to a reduction (hypoesthesia) or loss (anesthesia) of sensitivity of the cornea.

The most common causes of loss of corneal sensitivity are viral infections (herpes simplex and herpes zoster ophthalmicus), chemical burns, physical injuries, corneal surgery, neurosurgery, chronic use of topical medications, or chronic use of contact lenses.

Possible causes also include systemic diseases such as diabetes, multiple sclerosis or leprosy.

Other, albeit less frequent, potential causes of the disease are: intracranial space-occupying lesions such as neuroma, meningioma and aneurysms, which may compress the trigeminal nerve and reduce corneal sensitivity.

Conversely, congenital conditions that may lead to this disorder are very rare.

Brown atrophy of the heart is atrophy of the heart muscle (or myocardium) commonly found in the elderly. It is described as brown because fibers become pigmented by intracellular lipofuscin deposits (mostly around the cell nucleus) a type of lipochrome granule.

It has no known effect on function, and is described as being expected or normal in aging.

Other types of brown atrophy include brown atrophy of neuronia and brown atrophy of the liver.

Cornea verticillata, also called Fleischer vortex, vortex keratopathy or whorl keratopathy, is a condition characterised by corneal deposits at the level of the basal epithelium forming a faint golden-brown whorl pattern. It is seen in Fabry disease or in case of prolonged amiodarone intake.

Patients are normal at birth and the syndrome manifests during childhood and puberty. The enchondromas affect the extremities and their distribution is asymmetrical. The most common sites of enchondromas are the metacarpal bones and phalanges of the hands. The feet are less commonly afflicted.

Disfigurations of the extremities are a result. Pathological fractures can arise in affected metaphyses and diaphyses of the long bones and are common (26%).

The risk for sarcomatous degeneration of enchondromas, hemangiomas, or lymphangiomas is 15-30% in the setting of Maffucci syndrome. Maffucci syndrome is associated with a higher risk of CNS, pancreatic, and ovarian malignancies. Multiple enchondromas may present in 3 disorders: Ollier disease, Maffucci syndrome, and metachondromatosis. It is important to make the distinction between these diseases, particularly Ollier disease and Maffucci syndrome. Ollier disease is more common than Maffucci syndrome, and presents with multiple enchondromas often in a unilateral distribution. However, hemangiomas and lymphangiomas are not seen in Ollier disease. Metachondromatosis demonstrates autosomal-dominant transmission and presents with both multiple osteochondromas and enchondromas.

Metastatic calcification involves a systemic calcium excess imbalance, which can be caused by hypercalcemia, kidney failure, milk-alkali syndrome, lack or excess of other minerals, or other causes.

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

In Ollier disease isolated enchondromas are present without the presence of hemangiomas.

Focal proliferative nephritis is a type of glomerulonephritis seen in 20% to 35% of cases of lupus nephritis, classified as type III. As the name suggests, lesions are seen in less than half of the glomeruli. Typically, one or two foci within an otherwise normal glomerulus show swelling and proliferation of endothelial and mesangial cells, infiltration by neutrophils, and/or fibrinoid deposits with capillary thrombi. Focal glomerulonephritis is usually associated with only mild microscopic hematuria and proteinuria; a transition to a more diffuse form of renal involvement is associated with more severe disease.

Fleischer rings are pigmented rings in the peripheral cornea, resulting from iron deposition in basal epithelial cells, in the form of hemosiderin. They are usually yellowish to dark-brown, and may be complete or broken.

They are named for Bruno Fleischer.

Fleischer rings are indicative of keratoconus, a degenerative corneal condition that causes the cornea to thin and change to a conic shape.

Schnyder crystalline corneal dystrophy (SCD) is a rare form of corneal dystrophy. It is caused by heterozygous mutations in UBIAD1 gene. Cells in the cornea accumulate cholesterol and phosopholipid deposits leading to the opacity, in severe cases requiring corneal transplants. Abnormal cholesterol metabolism has been noted in other cell types of affected patients (skin fibroblasts) suggesting that this may be a systemic disorder with clinical manifestations limited to the cornea.

Conjunctival suffusion is an eye finding occurring early in Weil’s disease, which is caused by "Leptospira interrogans". Conjunctival suffusion is characterized by redness of the conjunctiva that resembles conjunctivitis, but it does not involve inflammatory exudates. Swelling of the conjunctiva (chemosis) is seen along the corners of the eye (palpebral fissures).

About 30 percent of patients with Weil's disease develop conjunctival suffusion. When it does occur, it develops towards the end of the early phase of the illness. Even in severe cases, the suffusion occurs in the first phase of the illness.

Conjunctival suffusion may also occur in patients with a Hantavirus infection. In a 1994 study of 17 patients with Hantavirus infections, 3 had conjunctival suffusion.

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

Some confusion exists between Fleischer rings and Kayser-Fleischer rings. Kayser-Fleischer rings are caused by copper deposits, and are indicative of Wilson's disease, whereas Fleischer rings are caused by iron deposits. One example of a medical condition that can present with Fleischer rings is Keratoconus.

Lattice corneal dystrophy type, also known as Biber-Haab-Dimmer dystrophy, is a rare form of corneal dystrophy. It has no systemic manifestations, unlike the other type of the dystrophy, Lattice corneal dystrophy type II. Lattice corneal dystrophy was first described by Swiss ophthalmologist Hugo Biber in 1890.

Lattice dystrophy gets its name from an accumulation of amyloid deposits, or abnormal protein fibers, throughout the middle and anterior stroma.

In case of corneal erosion, a doctor may prescribe eye drops and ointments to reduce the friction on the eroded cornea. In some cases, an eye patch may be used to immobilize the eyelids. With effective care, these erosions usually heal within three to seven days, although occasional sensations of pain may occur for the next six-to-eight weeks. As patients with LCD suffer with dry eyes as a result of erosion, a new technique involving the insertion of punctal plugs (both upper and lower) can reduce the amount of drops used a day, aiding ocular stability.

By about age 40, some people with lattice dystrophy will have scarring under the epithelium, resulting in a haze on the cornea that can greatly obscure vision. In this case, a corneal transplantation may be needed. There have been many cases in which teenage patients have had the procedure, which accounts for the change in severity of the condition from person to person.

Although people with lattice dystrophy have an excellent chance for a successful corneal transplantation, the disease may also arise in the donor cornea in as little as three years. In one study, about half of the transplant patients with lattice dystrophy had a recurrence of the disease between two and 26 years after the operation. Of these, 15 percent required a second corneal transplant. Early lattice and recurrent lattice arising in the donor cornea responds well to treatment with the excimer laser.

Phototherapeutic keratectomy (PTK) using [Excimer laser] can restore and preserve useful visual function for a significant period of time in patients with anterior corneal dystrophies.

Neurotrophic keratitis (NK) is a degenerative disease of the cornea caused by damage of the trigeminal nerve, which results in impairment of corneal sensitivity, spontaneous corneal epithelium breakdown, poor corneal healing and development of corneal ulceration, melting and perforation.

Neurotrophic keratitis is classified as a rare disease, with an estimated prevalence of less than 5 in 10,000 people in Europe. It has been recorded that on average, 6% of herpetic keratitis cases may evolve to this disease, with a peak of 12.8% of cases of keratitis due to herpes zoster virus.

The diagnosis, and particularly the treatment of neurotrophic keratitis are the most complex and challenging aspects of this disease, as a satisfactory therapeutic approach is not yet available.

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.

It results from cholesterol deposits in or hyalinosis of the corneal stroma, and may be associated with ocular defects or with familial hyperlipidemia. It is common in the apparently healthy middle aged and elderly; a prospective cohort study of 12,745 Danes followed up for a mean of 22 years found that it had no clinical value as a predictor of cardiovascular disease.

It can be a sign of disturbance in lipid metabolism, an indicator of conditions such as hypercholesterolemia, hyperlipoproteinemia or hyperlipidemia.

Unilateral arcus is a sign of decreased blood flow to the unaffected eye, due to carotid artery disease or ocular hypotony.

People over the age of 60 may present with a ring-shaped, grayish-white deposit of phospholipid and cholesterol near the peripheral edge of the cornea.

Younger people with the same abnormality at the edge of the cornea would be termed arcus juvenilis.

Several aetiologies are suggested, and any combination of these may be present in any given case.

- Vitamin deficiency (A, B or C)

- Viral infection

- Bacterial infection

- "Leptospira

- "Streptococcus

- "Brucella

- Parasitic infection

- Strongyle

- "Onchocerca cervicalis"

- Autoimmune disease

The disease has been suggested to be primarily autoimmune in nature, being a delayed hypersensitivity reaction to any of the above agents.

Membranoproliferative glomerulonephritis ("MPGN"), also known as mesangiocapillary glomerulonephritis, is a type of glomerulonephritis caused by deposits in the kidney glomerular mesangium and basement membrane (GBM) thickening, activating complement and damaging the glomeruli.

MPGN accounts for approximately 4% of primary renal causes of nephrotic syndrome in children and 7% in adults.

It should not be confused with membranous glomerulonephritis, a condition in which the basement membrane is thickened, but the mesangium is not.