Lisch epithelial corneal dystrophy (LECD), also known as band-shaped and whorled microcystic dystrophy of the corneal epithelium, is a rare form of corneal dystrophy first described in 1992 by Lisch et al. In one study it was linked to chromosomal region Xp22.3, with as yet unknown candidate genes.

The main features of this disease are bilateral or unilateral gray band-shaped and feathery opacities. They sometimes take on a form of a whirlpool, repeating the known pattern of corneal epithelium renewal. Abrasion of the epithelium in 3 patients brought only temporary relief, with abnormal epithelium regrowth in several months.

Epithelial cells in the zones of opacity were shown to have diffuse cytoplasmic vacuoles with as yet unestablished content.

Onset occurs in the first decade, usually between ages 5 and 9. The disorder is progressive. Minute, gray, punctate opacities develop. Corneal sensitivity is usually reduced. Painful attacks with photophobia, foreign body sensations, and recurrent erosions occur in most patients. Macular corneal dystrophy is very common in Iceland and accounts for almost one-third of all corneal grafts performed there.

Thiel–Behnke dystrophy, or Corneal dystrophy of Bowman layer, type II, is a rare form of corneal dystrophy affecting the layer that supports corneal epithelium.

The dystrophy was first described in 1967 and initially suspected to denote the same entity as the earlier-described Reis-Bucklers dystrophy, but following a study in 1995 by Kuchle et al. the two look-alike dystrophies were deemed separate disorders.

The age of onset is in a child's infancy. Bilateral corneal opacification started in the second year of life and led to severe visual impairment. However, cornea surgery and replacement resulted in better vision.

Symptoms include a combination of spinocerebellar degeneration and corneal dystrophy. Mental retardation and slowly progressive cerebellar abnormalities were also diagnosed in patients. Other symptoms include corneal edema, thickening of Descemet membrane, and degenerative pannus. Abnormalities were found in muscle and sural nerves.

Hair growth on the head is noticeably less full than normal, and the hairs are very weak; the rest of the body shows normal hair.

The macular degeneration comes on slowly with deterioration of central vision, leading to a loss of reading ability. Those affected may otherwise develop in a completely healthy manner; life expectancy is normal.

Terrien marginal degeneration is a noninflammatory, unilateral or asymmetrically bilateral, slowly progressive thinning of the peripheral corneal stroma.

The cause of Terrien marginal degeneration is unknown, its prevalence is roughly equal between males and females, and it usually occurs in the second or third decade of life.

Symptoms of pterygium include persistent redness, inflammation, foreign body sensation, tearing, dry and itchy eyes. In advanced cases the pterygium can affect vision as it invades the cornea with the potential of obscuring the optical center of the cornea and inducing astigmatism and corneal scarring. Many patients do complain of the cosmetic appearance of the eye either with some of the symptoms above or as their major complaint.

The main pathological features in this dystrophy are mulberry-shaped gelatinous masses beneath the corneal epithelium. Patients suffer from photophobia, foreign body sensation in the cornea. The loss of vision is severe. The amyloid nodules have been found to contain lactoferrin, but the gene encoding lactoferrin is unaffected.

This form of corneal amyloidosis appears to be more frequent in Japan.

Macular corneal dystrophy, also known as Fehr corneal dystrophy named for German ophthalmologist Oskar Fehr (1871-1959), is a rare pathological condition affecting the stroma of cornea. The first signs are usually noticed in the first decade of life, and progress afterwards, with opacities developing in the cornea and attacks of pain. The condition was first described by Arthur Groenouw in 1890.

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 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.

Epithelial basement membrane dystrophy (EBMD), also known as map-dot-fingerprint dystrophy and Cogans's microcystic dystrophy, is a disorder of the eye that can cause pain and dryness.

It is sometimes included in the group of corneal dystrophies. It diverges from the formal definition of corneal dystrophy in being in most cases non-familial. It also has a fluctuating course, while for a typical corneal dystrophy the course is progressive. When it is considered part of this group, it is the most common type of corneal dystrophy.

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 elevates the corneal epithelium, eventually leading to corneal erosions that prompt attacks of ocular hyperemia, pain, and photophobia. These recurrent painful corneal epithelial erosions often begin as early as 1 year of age.

With time, the corneal changes progress into opacities in Bowman's membrane, which gradually becomes more irregular and more dense. Significant vision loss may occur. However, vascularization of the cornea is not present.

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.

Gelatinous drop-like corneal dystrophy, also known as amyloid corneal dystrophy, is a rare form of corneal dystrophy. The disease was described by Nakaizumi as early as 1914.

Pain is not typically present in pellucid marginal degeneration, and aside from vision loss, no symptoms accompany the condition. However, in rare cases, PMD may present with sudden onset vision loss and excruciating eye pain, which occurs if the thinning of the cornea leads to perforation. While PMD usually affects both eyes, some unilateral cases have been reported.

PMD is characterized by bilateral thinning (ectasia) in the inferior and peripheral region of the cornea. The distribution of the degeneration is crescent or arcuate shaped. The cornea just above the region of thinning is of normal thickness, and may protrude anteriorly, which creates an irregular astigmatism. This is described as a "beer belly" appearance since the greatest protrusion occurs below the horizontal midline (unlike keratoconus). Normally, PMD does not present with vascularization of the cornea, scarring, or any deposits of lipid.

Corneal-cerebellar syndrome (also known as Der Kaloustian-Jarudi-Khoury syndrome) is an autosomally resessive disease that was first described in 1985. Three cases are known: all are sisters in the same family.

Patients may complain of severe problems with dry eyes, or with visual obscurations. It can also be asymptomatic, and only discovered because of subtle lines and marks seen during an eye exam.

EBMD is a bilateral anterior corneal dystrophy characterized by grayish epithelial fingerprint lines, geographic map-like lines, and dots (or microcysts) on slit-lamp examination. Findings are variable and can change with time. While the disorder is usually asymptomatic, up to 10% of patients may have recurrent corneal erosions, usually beginning after age 30; conversely, 50% of patients presenting with idiopathic recurrent erosions have evidence of this dystrophy.

It is also called "arcus adiposus", "arcus juvenilis" (when it occurs in younger individuals), "arcus lipoides corneae" or "arcus cornealis"; sometimes a "gerontoxon".

Pellucid marginal degeneration (PMD), is a degenerative corneal condition, often confused with keratoconus. It is typically characterized by a clear, bilateral thinning (ectasia) in the inferior and peripheral region of the cornea, although some cases affect only one eye. The cause of the disease remains unclear.

The term "pellucid marginal degeneration" was first coined in 1957 by the ophthalmologist Schalaeppi. The word "pellucid" means clear, indicating that the corneas retain clarity in pellucid marginal degeneration.

Hypotrichosis with juvenile macular dystrophy (HJMD or CDH3) is an extremely rare congenital disease characterized by sparse hair growth (hypotrichosis) from birth and progressive macular corneal dystrophy.

Corneal ectatic disorders or corneal ectasia are a group of uncommon, noninflammatory, eye disorders characterised by bilateral thinning of the central, paracentral, or peripheral cornea.

- Keratoconus, a progressive, noninflammatory, bilateral, asymmetric disease, characterized by paraxial stromal thinning and weakening that leads to corneal surface distortion.

- Keratoglobus, a rare noninflammatory corneal thinning disorder, characterised by generalised thinning and globular protrusion of the cornea.

- Pellucid marginal degeneration, a bilateral, noninflammatory disorder, characterized by a peripheral band of thinning of the inferior cornea.

- Posterior keratoconus, a rare condition, usually congenital, which causes a nonprogressive thinning of the inner surface of the cornea, while the curvature of the anterior surface remains normal. Usually only a single eye is affected.

- Post-LASIK ectasia, a complication of LASIK eye surgery.

- Terrien's marginal degeneration, a painless, noninflammatory, unilateral or asymmetrically bilateral, slowly progressive thinning of the peripheral corneal stroma.

Dental features:

- small teeth in males

- pointed (screwdriver shaped or conical) incisors (sometimes called Hutchinson teeth)

- incisors with an irregulal incisal edge

- canines: enlarged and globular; may be dome or bud shaped with trilobed edge

- premolars and molars: small, round and globular; may have supernumary lobes (mulberry or lotus flower shape)

- widely separated teeth (diastemma)

- hypoplastic enamel

- dental agenesis

- presence of mesiodents (median incisor behind normal upper incisors)

- pulp chamber anomalies

Facial features:

- anteverted pinnae

- long face

- prominent nasal bridge and nose

- prognathism occasionally

Ophthalmic features:

- bilateral congenital nuclear opacities (100%)

- severe amblyopia

- nystagmus (93%)

- strabismus (43%)

- microcornea (96%)

- congenital glaucoma

- scleral staphylomas

- retinal cystoid degeneration

- microphthalmia

These lead to severe visual impairment in affected males.

Other:

- The fourth metacarpal may be shortened

30% of patients also have some degree of intellectual impairment: of these 80% are mildly to moderately affected: the other 20% may have developmental delays and behavior problems.

Carrier females display milder variable symptoms of disease. Ocular signs are present in 90% of heterozygous females. These are typically lens opacities often involving the posterior Y sutures. More rarely dental anomalies and the characteristic facial features may also occur.

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.

To clarify whether Thiel–Behnke corneal dystrophy is a separate entity from Reis-Bucklers corneal dystrophy, Kuchle et al. (1995) examined 28 corneal specimens with a clinically suspected diagnosis of corneal dystrophy of the Bowman layer by light and electron microscopy and reviewed the literature and concluded that 2 distinct autosomal dominant corneal dystrophy of Bowman layer (CBD) exist and proposed the designation CDB type I (geographic or 'true' Reis-Bucklers dystrophy) and CDB type II (honeycomb-shaped or Thiel–Behnke dystrophy). Visual loss is significantly greater in CDB I, and recurrences after corneal transplantation seem to be earlier and more extensive in CDB I.

Spectacles or RGP contact lenses can be used to manage the astigmatism. when the condition worsens, surgical correction may be required.