Vitreoretinal membrane shrinkage or contraction secondary to the proliferation of primarily retinal pigment epithelial cells and glial cells, particularly fibrous astrocytes, followed by membrane formation. The formation of fibrillar collagen and cellular proliferation appear to be the basis for the contractile properties of the epiretinal and vitreous membranes.

Marshall syndrome (MRSHS) is characterized by midfacial hypoplasia, cleft palate, ocular anomalies including high myopia and cataracts, sensorineural hearing loss, short stature with spondyloepiphyseal dysplasia, and arthropathy. In contrast to Stickler syndrome type II, it has less severe eye findings but striking ocular hypertelorism, more pronounced maxillary hypoplasia, and ectodermal abnormalities (summary by Shanske et al., 1997 and Ala-Kokko and Shanske, 2009).

Osteoporosis-pseudoglioma syndrome (OPPG) is an autosomal recessive disorder characterized by severe osteoporosis and visual disturbance from childhood. Juvenile onset of osteoporosis manifests as long-bone fractures, vertebral compression fractures, kyphoscoliosis, deformity of extremities, and short stature. Congenital or early-onset visual disturbances arise from ophthalmologic problems including retinal detachment and microphthalmia (summary by Narumi et al., 2010).

Wagner vitreoretinopathy (WGVRP) is a rare vitreoretinal degeneration inherited as an autosomal dominant trait, first described in a large Swiss pedigree (Wagner, 1938) and subsequently identified in other families. Penetrance in Wagner syndrome is complete, and the disease manifests in childhood or adolescence with a progressive course. Affected individuals usually present with an 'empty' vitreous cavity with fibrillary condensation or avascular strands and veils. Additional features, which are variable and age-dependent, include chorioretinal atrophy with loss of the retinal pigment epithelium (RPE), lattice degeneration of the retina, complicated cataracts, mild myopia, and peripheral traction retinal detachment. Rod and cone electroretinography shows reduced b-wave amplitude and correlates with severe chorioretinal pathology. It is believed that liquefaction of vitreous initiates a degenerative cascade that results in the complex eye phenotype of Wagner syndrome (summary by Kloeckener-Gruissem et al., 2006). Patients with additional ocular features such as progressive nyctalopia (night blindness), visual field constriction, and chorioretinal atrophy, with loss of RPE and choriocapillaries on fluorescein angiography and rod-cone abnormalities on electroretinography, were initially believed to have a distinct clinical entity, which was designated 'erosive vitreoretinopathy' (ERVR). Extraocular abnormalities are not present in patients diagnosed with Wagner or erosive vitreoretinopathy (summary by Mukhopadhyay et al., 2006).

Hereditary human retinal degenerative diseases usually affect the mature photoreceptor topography by reducing the number of cells through apoptosis, resulting in loss of visual function. Only one inherited retinal disease, the enhanced S-cone syndrome (ESCS), manifests a gain in function of photoreceptors. ESCS is an autosomal recessive retinopathy in which patients have increased sensitivity to blue light; perception of blue light is mediated by what is normally the least populous cone photoreceptor subtype, the S (short wavelength, blue) cones. People with ESCS also suffer visual loss, with night blindness occurring from early in life, varying degrees of L (long, red)- and M (middle, green)-cone vision, and retinal degeneration. The pattern of retinal dysfunction is a constant among ESCS patients, but the degree of clinically evident retinal degeneration can vary from minimal to severe. The latter condition is known as Goldmann-Favre syndrome. The altered ratio of S- to L/M-cone photoreceptor sensitivity in ESCS may be due to abnormal cone cell fate determination during retinal development (summary by Haider et al., 2000). Goldmann-Favre syndrome is characterized by a liquefied vitreous body with preretinal band-shaped structures (veil), macular changes in the form of retinoschisis or edema and pigmentary degeneration of the retina with hemeralopia and extinguished electroretinogram. Cataract is a complication. The disorder is to be distinguished from X-linked retinoschisis (312700) and from autosomal dominant hyaloideoretinal degeneration (143200).

Pigmented paravenous chorioretinal atrophy is a stationary disease of the ocular fundus in which bone corpuscle pigmentation is seen in a paravenous distribution. Patients are usually asymptomatic; diagnosis is based on the characteristic fundus appearance. Most cases have been reported in males (summary by Traboulsi and Maumenee, 1986).

Stickler syndrome is a connective tissue disorder that can include ocular findings of myopia, cataract, and retinal detachment; hearing loss that is both conductive and sensorineural; midfacial underdevelopment and cleft palate (either alone or as part of the Pierre Robin sequence); and early-onset degenerative joint disease. Variable phenotypic expression of Stickler syndrome occurs both within and among families; interfamilial variability is in part explained by locus and allelic heterogeneity.

Spondyloepiphyseal dysplasia congenita (SEDC) is an autosomal dominant chondrodysplasia characterized by disproportionate short stature (short trunk), abnormal epiphyses, and flattened vertebral bodies. Skeletal features are manifested at birth and evolve with time. Other features include myopia and/or retinal degeneration with retinal detachment and cleft palate (summary by Anderson et al., 1990).

Stickler syndrome is a connective tissue disorder that can include ocular findings of myopia, cataract, and retinal detachment; hearing loss that is both conductive and sensorineural; midfacial underdevelopment and cleft palate (either alone or as part of the Pierre Robin sequence); and early-onset degenerative joint disease. Variable phenotypic expression of Stickler syndrome occurs both within and among families; interfamilial variability is in part explained by locus and allelic heterogeneity.

Knobloch syndrome-1 (KNO1) is an autosomal recessive developmental disorder primarily characterized by typical eye abnormalities, including high myopia, cataracts, dislocated lens, vitreoretinal degeneration, and retinal detachment, with occipital skull defects, which can range from occipital encephalocele to occult cutis aplasia (summary by Aldahmesh et al., 2011). Genetic Heterogeneity of Knobloch Syndrome KNO2 (618458) is caused by mutation in the PAK2 gene (605022) on chromosome 3q29.

Knobloch syndrome-2 (KNO2) is characterized by severe vitreoretinal degeneration associated with occipital skull defects, ranging from mild encephalocele to abnormally pigmented hair. Developmental delay may be mild or severe (Antonarakis et al., 2022). For a general phenotypic description and discussion of genetic heterogeneity of Knobloch syndrome, see KNO1 (267750).