Sclerocornea

While the exact historical origins of its documentation are unclear, studies on sclerocornea has long been recognized in ophthalmology as a rare but significant anomaly going as far back as the 1960's.

The condition usually affects both eyes and it does not worsen overtime, the symptoms and severity are present from birth and generally remain stable.

[1] As a result and depending on the variety, the patient may have poor vision from birth and in some cases problems with eye movement, such as nystagmus or strabismus.

[4] The exact cause of Sclerocornea is not fully understood, but it is believed to involve genetics and developmental factors during fetus development.

[1] There are findings suggesting that a genetic locus at chromosome 22q11.2 plays a crucial role in the formation and development of the eye during the early stages of embryonic growth.

The condition is thought to occur because the neural crest cells don't move or develop correctly between the 7th and 10th week of pregnancy.

[6] The main problem affected in sclerocornea occurs in the cornea, which doesn’t develop correctly and starts to look more like the white part of the eye (the sclera).

There are also studies coming out stating that a mutation or deletions in the gene RAD21 might be causing the bad development of neural crest cells.

[8] Diagnosis typically involves a pediatric ophthalmologist after a basic outpatient examination and might require a geneticist for counseling if an inherited form is suspected.

[11] Primary treatment for Sclerocornea is Penetrating keratoplasty (PK), it is only considered for severe cases although success rates are variable due to risks like graft rejection and glaucoma.

[13] Non surgical options include refractive correction, such as glasses or contacts if possible or optical iridotomy, this can be considered for milder cases.

In patients with partial sclerocornea, optical correction, with glasses, should be performed early in order to avoid amblyopia due to high hyperopia.

Anatomy of the human eye
Phenotypic appearance in patients with sclerocornea, aphakia, and microphthalmia.
Vertebrate eye development (human eye). (A) During early vertebrate development, the eye field is established at the boundary between the telencephalon (brown) and the diencephalon (green). (B) Optic vesicles bilaterally protrude from either side of the forebrain approaching the thickened surface ectoderm (lens placodes). (C) The interaction between the optic vesicle and the lens placode of the surface ectoderm results in optic vesicle invagination, optic cup formation and lens placode evagination (lens pit). Simultaneously, the optic fissure is formed along the inferonasal aspect of the optic cup, which surrounds the hyaloid artery. (D) Continued evagination of surface ectoderm leads to the formation of an independent lens vesicle.
Penetrating keratoplasty. The goal is improve the vision or if not, restore the integrity of the ocular globe
Slit lamp exam
(C) Peters anomaly shows central corneal opacification (black arrows) reflecting the abnormal separation of the lens vesicle from the surface ectoderm looking similar to scleracornea
RAD21 has many roles including DNA damage repair, transcription regulation, DNA replication, and centrosome biogenesis, etc. Diseases rise when mutations in RAD21 disrupt its function (in green).