Meet Libby. Corneal Dysgenesis, Degeneration, and Dystrophies Definitions. Dr. Victor Malinovsky

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Meet Libby Corneal Dysgenesis, Degeneration, and Dystrophies 2006 Dr.

disorder that results in a congenital malformation of the cornea & anterior

into three categories: developmental arrest, abnormal differentiation or a

elements of corneal tissue are converted into some abnormal substance,

causes deterioration and sometimes impairs function: no family history or

definite underlying cause, tendency to develop near the periphery, in advanced

asymmetric Secondary degeneration or keratopathy are less common, of known

1 Meet Libby Corneal Dysgenesis, Degeneration, and Dystrophies 2006 Dr. Victor Malinovsky Definitions Dysgenesis: (congenital anomalies) A development disorder that results in a congenital malformation of the cornea & anterior segment, the etiology can be genetic, infectious, traumatic, or toxic: fall into three categories: developmental arrest, abnormal differentiation or a combination of the two Degeneration: A disease process in which chemical elements of corneal tissue are converted into some abnormal substance, representing a change in the corneal tissue to a less functional active form, causes deterioration and sometimes impairs function: no family history or genetic predisposition Primary or evolutional degeneration are common with no definite underlying cause, tendency to develop near the periphery, in advanced age, without early loss of vision, may be unilateral or bilateral, often asymmetric Secondary degeneration or keratopathy are less common, of known cause, such as general metabolic disturbance, previous injury, or inflammation, can be accompanied by neovascularization 1

Dystrophy Developmental, symmetric, and frequently hereditary changes occurring in original corneal tissue because of faulty nutrition, unrelated to other systemic or local diseases Starts in center

2 Dystrophy Developmental, symmetric, and frequently hereditary changes occurring in original corneal tissue because of faulty nutrition, unrelated to other systemic or local diseases Starts in center of relatively young persons, with early and progressive visual impairment, non-inflammatory, avascular and bilateral Dysgenesis Abnormalities of size and curvature Cryptophthalmos: rare condition in which the lids fail to form and absence of cornea (undergo metaplasia into skin) Cornea plana (flat cornea- 38 D or less) Rare, bilateral condition Usually seen in association with sclerocornea, microcornea, microphthalmos Diffuse opacities of stroma, shallow anterior chamber, congenital cataracts, coloboma of iris, ectopica lentis, retinal and macular/aplasia, blue sclera, and predisposition to angle closure glaucoma Inherited (dominant or recessive trait) Microcornea A cornea with a diameter of less than 10 mm The anterior chamber is shallow Eye may be otherwise normal or be microphthalmos (entire eye small and malformed), cornea is clear Associated ocular abnormalities: cornea plana, glaucoma (congenital or later, closed or open angle), coloboma, leukoma, congenital cataract, corectopia, microphakia, optic nerve hypoplasia Systemic associations: fetal alcohol rubella syndrome and Ehlers-Danlos syndrome (hypermobile joints and hyperextensibility of skin), many others Autosomal dominant or recessive 2

Megalocornea Enlargement of the cornea beyond 13 mm in horizontal diameter with a clear cornea in adult or 12mm or

$no treatment except for refractive errors (high myopia and astigmatism) The condition must be distinguished from$ glaucoma, cataracts Associated with systemic syndromes ie.

glaucoma, cataracts Associated with systemic syndromes ie.

few years of life, rare, more often males Ocular signs are diffuse corneal edema, increased intraocular pressure,

3 Megalocornea Enlargement of the cornea beyond 13 mm in horizontal diameter with a clear cornea in adult or 12mm or more in a newborn This rare condition is usually bilateral, sexlinked (90% are males), non-progressive, and requires no treatment except for refractive errors (high myopia and astigmatism) The condition must be distinguished from corneal enlargement due to congenital glaucoma Cornea is clear, deep chamber, high myopia, prone to ectopia lentis, glaucoma, cataracts Associated with systemic syndromes ie. Marfan syndrome Congenital glaucoma May occur at birth, may develop early in newborn period, or may develop by first few years of life, rare, more often males Ocular signs are diffuse corneal edema, increased intraocular pressure, glaucomatous cupping, increased corneal diameter, rupture of Descemet s membrane (Haab straie) and buphthalmos, blue sclera, often bilateral Impaired aqueous outflow, due maldevelopement of angle 3

Ocular symptoms are photophobia, tearing, and blepharospasms Differential

$refractive errors often occur Keratoglobus A rare bilateral globular$ configuration of the cornea which can resemble keratoconus with exception

configuration of the cornea which can resemble keratoconus with exception

periphery, onset at birth Decreased vision from myopia and astigmatism,

4 Ocular symptoms are photophobia, tearing, and blepharospasms Differential diagnosis: forceps injury, corneal endothelial dystrophy, interstitial keratitis, and congenital rubella syndrome Myopic and astigmatic refractive errors often occur Keratoglobus A rare bilateral globular configuration of the cornea which can resemble keratoconus with exception that the cornea is diffusely, uniformly thinned, particularly in periphery, onset at birth Decreased vision from myopia and astigmatism, difficult management Rupture of the globe can occur easily and patients must be cautioned to avoid trauma 4

Anterior Segment or Iridocorneal Dysgenesis: a spectrum of overlapping, rare, congenital malformations involving the cornea, iris, or filtration angle, and lens that appear to be related to abnormal

mesenchyme is probably derived from the abnormal neural crest development not mesoderm ASD represents abnormal migration or differentiation of the secondary mesenchyme Posterior Embryotoxin

5 Anterior Segment or Iridocorneal Dysgenesis: a spectrum of overlapping, rare, congenital malformations involving the cornea, iris, or filtration angle, and lens that appear to be related to abnormal development of the mesenchyme forming the anterior segment of the eye These abnormalities were previously referred to as mesodermal dysgenesis or anterior chamber cleavage syndrome Embryonic mesenchyme is probably derived from the abnormal neural crest development not mesoderm ASD represents abnormal migration or differentiation of the secondary mesenchyme Posterior Embryotoxin Thickened, prominent, curved, centrally displaced anterior border ring of Schwalbe s ring A circumferential, white, collagenous, irregular ridge or band about 0.5 to 2 mm central to the limbus, located peripherally on the posterior surface of the cornea, at the juncture of the DM and the TM, occurring in about 15% of normal eyes Seen temporally & nasally more often May form a complete ring studded with pigment clumps or occasionally dislocated from the cornea and hangs in the angle 5

Glaucoma Glaucoma is a complication which has only recently been confirmed as a feature of

1.2.4 OPHTHALMOLOGICAL ABNORMALITIES Ocular abnormalities are well documented in patients with NPS 6 62 81 95. 1.2.4.1 Glaucoma Glaucoma is a complication which has only recently been confirmed as a feature