autosomal dominant

Bilateral congenital cataracts are usually present together with upward-slanting and narrowed lid fissures.  The upper eyelids appear abnormally thick and epicanthus is common.  Nothing is known about the location or morphology of the lens opacities.

Lens opacification is the only ocular sign of this disorder.  These may be congenital and nuclear in location but this is variable.  Pulverulent and ‘sunflower’ light-diffracting opacities have also been described and are likely responsible for the glare that many patients experience.  In some patients cataracts may not be diagnosed until adult life.  Ferritin levels in surgically removed lenses are 1,500 times higher than controls and histochemical studies demonstrate that the crystalline lens opacities consist of intracellular L-ferritin.

The ocular phenotype has not been well defined in this condition since few families have been reported.  Microphthalmia is present in some patients.  The corneas may be small and there is often some conjunctival growth over the limbus.

The retinal features consist of lacunar depigmentation of the RPE and in some cases resemble the lesions of congenital toxoplasmosis.  Eighty to 90 per cent of patients have areas of atrophic and dysplastic-appearing lesions of the retina and choroid with vascular attenuation.  The edges of lacunae may have patchy hyperpigmentation.  These lesions are usually static but may show mild progression.  Visual acuity is generally stable or only mildly progressive.  However, other patients have a severe reduction in acuity.  ERG responses are reduced.

Optic disc dysplasia is the ocular hallmark of this disease.  The nerve head often has the appearance of the ‘morning glory’ anomaly but some authors describe this as a coloboma or an optic pit.  Iris colobomas do not occur and only two patients have been reported with retinal colobomas.  There may be severe visual impairment due to the dysplastic optic nerves, but macular and retinal malformations may also contribute.  Other patients have near normal vision. The central retinal vessels are anomalous or even absent with the multiple smaller vessels exiting from the periphery of the disc.  The retina and fovea have been described as hypoplastic and have pigmentary changes. There is often a superonasal visual field defect.  Retrobulbar optic nerve cysts, high myopia, and posterior staphylomas have been noted in a few patients.  As in most autosomal dominant disorders, there is considerable clinical variability.

Bilateral lens opacities may be both nuclear and zonular.  The embryonic and fetal nuclei are usually involved and diffuse cortical opacities may also be seen in some patients.  The involved area is therefore larger than the somewhat similar Coppock-like cataract (604307) which is limited to the embryonic nucleus.  The lens opacities may be seen at birth or in early childhood and usually progress. There is considerable clinical variation in the degree and distribution of the usual dust-like opacities which may also be lamellar in distribution with a clear peripheral cortex and minimal nuclear involvement.  Microcornea has also been reported.  In mild cases the lens opacities are primarily clustered along the Y sutures resembling congenital zonular cataracts with sutural opacities (600881).

Three unrelated patients with mutations in GJA8 and total sclerocornea have been reported.  Two of these patients in addition had small abnormal lenses while the third had cataracts and micropthalmia.  Two of the three also develped glaucoma by one year of age.

The nature and morphology of the lens opacities in an adult have been studied by light and scanning electron microscopy.  They are located in the embryonic and fetal nuclei and appear "puffy" with lens fiber irregulaties and entanglement in adjacent areas.