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The term coloboma is derived from the Greek word “Koloboma,” which means “hole.” Coloboma of lens is usually unilateral, but in some cases bilateral and double coloboma may be present. The zonules may be mal-developed, which may be due either to typically incomplete closure of the optic vesicle, or to persistent remnants of fibrovascular sheath of the lens interfering with development of zonules.
Coloboma may occur as an isolated defect or as a feature of a variety of single-gene disorders, chromosomal syndromes or malformation syndromes. Although not classically associated with Marfan syndrome, colobomas have been described in several reports of Marfan syndrome, typically involving the lens and rarely involving other ocular structures. A lens coloboma is not a true coloboma; it is just a zonular absence that causes a defect in the lens equator and, hence, a more spherical lens.
These cases require adequate preoperative workup in the form of posterior segment examination and calculation of the corrective IOL power, as these cases may be associated with colobomas of the macula and optic disc. The IOL power calculation in such cases is often guided by the patient’s refraction and by measuring the distance to the patient’s preferred fixation. Patients often present with poor vision resulting from peripheral lenticular astigmatism and glare. Get the whole story