Megalocornea and microcornea
Last reviewed: 23.04.2024
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Since different tissues of the anterior segment of the eyeball are exposed to the same effects, congenital corneal pathology is often combined with pathological changes in the iris and / or glaucoma.
Despite the specific clinical manifestations of the disease for each individual structure, in all cases there are common features. Possible genetic predetermination of the emergence of isolated lesions of the anterior segment or a combination of anomalies in the development of the organ of vision with general pathology. Developmental disorders also occur as a result of toxic damage (including fetal alcohol syndrome).
[Megalocornea
Megalocornea is defined as a condition in which the horizontal diameter of the cornea exceeds 13 mm and does not tend to further increase. Intraocular pressure is within normal limits. The structure and thickness of the cornea, as a rule, are not changed. Other manifestations of this bilateral syndrome may include arcus juvenilis, mosaic dystrophy of the cornea, pigment dispersion, cataract and lens subluxation. The overwhelming type of refraction is low-grade myopia and astigmatism, as well as emmetropia. In most cases, the development of visual functions does not deviate from the norm. Most often, the disorder has an X-linked form of inheritance; the pathological gene is localized on the long arm of the X chromosome in the region of Xql2-q26. There are reports of autosomal recessive and autosomal dominant type of inheritance.
Perhaps a combination of megalocornea with such common diseases as:
- ichthyosis and congenital poikiloderma;
- Aarskog syndrome (Aarskog) is an X-linked recessive disorder characterized by low growth, hypertelorism, antimonogloidal incision of the eyes, change in the shape of the scrotum, and syndactyly;
- Marfan syndrome;
- a syndrome of mental retardation with megalocornea - mental retardation, low growth, ataxia and convulsions;
- Knine syndrome (Kneist);
- diabetes insipidus.
Concomitant pathology of the organ of vision:
- ectopia of the lens and pupil - a condition with an autosomal recessive type of inheritance, characterized by the presence of a perching pupillary membrane, a lens shift back, cataracts, myopia and an increased risk of detachment of the retina;
- congenital miosis;
- Rieger's syndrome;
- albinism;
- Weill-Marche-sani syndrome;
- Cruson's syndrome;
- Marshall-Smith syndrome (Marshall-Smith) - developmental delay, mental retardation and dysmorphia;
- dwarfism syndrome - low growth, loose joints, delayed development of the organ of vision and teeth, Rieger anomaly.
Microcornea
Microcornea is a rare condition in which the diameter of the cornea does not exceed 10 mm, while the parameters of the anterior segment of the eyeball are usually reduced, with the dimensions of the posterior segment unchanged.
Microcornea may accompany opacity and vascularization of the cornea, dysgenesis of the anterior segment, cataracts, congenital aphakia, coloboma, persistent vitreous hyperplasia (PGST), retinal dysplasia, as well as ipsilateral malformations of the face.