Cornea plana is clinically characterized by reduced corneal curvature leading in most cases to hyperopia, hazy corneal limbus, and arcus lipoides at an early age. CNA1, an autosomal dominant form of the disorder, is mild (summary by Tahvanainen et al., 1996). Genetic Heterogeneity of Cornea Plana Also see CNA2 (217300), an autosomal recessive form of the disorder, which is severe and frequently associated with additional ocular manifestations.

Cornea plana is clinically characterized by reduced corneal curvature leading in most cases to hyperopia, hazy corneal limbus, and arcus lipoides at an early age. CNA2 is a severe form of the disorder, which is frequently associated with additional ocular manifestations (summary by Tahvanainen et al., 1996). For discussion of genetic heterogeneity of CNA, see CNA1 (121400).

A rare genetic eye disease with characteristics of microcornea, coloboma of the iris and the optic disc, axial enlargement of the globe, staphyloma and severe myopia. Additional manifestations are mild cornea plana, iridocorneal angle abnormalities with elevation of intraocular pressure and shallow anterior chamber depth. Variable expressivity of the phenotype has been described, including unilateral or bilateral involvement or variable extent of coloboma among other features.

Brittle cornea syndrome (BCS) is characterized by blue sclerae, corneal rupture after minor trauma, keratoconus or keratoglobus, hyperelasticity of the skin, and hypermobility of the joints (Al-Hussain et al., 2004). It is classified as a form of Ehlers-Danlos syndrome (Malfait et al., 2017). For a discussion of genetic heterogeneity of brittle cornea syndrome, see BCS1 (229200).

Loeys-Dietz syndrome (LDS) is characterized by vascular findings (cerebral, thoracic, and abdominal arterial aneurysms and/or dissections), skeletal manifestations (pectus excavatum or pectus carinatum, scoliosis, joint laxity, arachnodactyly, talipes equinovarus, cervical spine malformation and/or instability), craniofacial features (widely spaced eyes, strabismus, bifid uvula / cleft palate, and craniosynostosis that can involve any sutures), and cutaneous findings (velvety and translucent skin, easy bruising, and dystrophic scars). Individuals with LDS are predisposed to widespread and aggressive arterial aneurysms and pregnancy-related complications including uterine rupture and death. Individuals with LDS can show a strong predisposition for allergic/inflammatory disease including asthma, eczema, and reactions to food or environmental allergens. There is also an increased incidence of gastrointestinal inflammation including eosinophilic esophagitis and gastritis or inflammatory bowel disease. Wide variation in the distribution and severity of clinical features can be seen in individuals with LDS, even among affected individuals within a family who have the same pathogenic variant.

Visual impairment and progressive phthisis bulbi is characterized by poor vision at birth, with development of bilateral phthisis by adulthood (Ansar et al., 2018).