Structural organization of choroidal colobomas of young and adult patients and mechanism of retinal detachment.
OBJECTIVE
In colobomatous eyes, the risk of retinal detachment increases with age. This study elucidates the anatomic conditions and pathologic process of retinal detachment associated with colobomas.


METHODS
The records, including histologic slides, of 14 children (1 day to 17 months old) and 7 adults (17 to 78 years old) with colobomas were examined.


RESULTS
In children, colobomas were associated with lethal malformations. The extracolobomatous inner retinal layers extended centrally, forming the intercalary membrane. Duplication of the outer retinal layers and a horizontal shift of Müllerian glia created a triangle and a locus minoris resistentiae adjacent to the laterally displaced pigment epithelium. Part of the locus was an incomplete layer of photoreceptors excluding Müllerian glia. In adults, atrophy of the intercalary membrane, manifested as central schisis, thinning of the neuroepithelium, and hole formation, was related to a paucity of blood vessels within and underneath the intercalary membrane and the size of colobomas. The margins featured blood vessels, pigment epithelial hypertrophy, and choroidal and scleral thickening in a compact, intertwined arrangement.


CONCLUSIONS
Glial atrophy, schisis, and hole formation in the intercalary membrane and separation of the locus minoris resistentiae from the pigment epithelium can disrupt barriers to fluid flow and set the stage for rhegmatogenous retinal detachment. That process is exacerbated by scleral ectasia, increasing vitreous traction at the margin, and retinovascular ischemia within the intercalary membrane. A vascularized, compact margin resembling a laser barrier, found predominantly in adults, may protect against retinal detachment.
Schubert
Hermann D
HD
Edward S. Harkness Eye Institute of New York Presbyterian Hospital in the City of New York, and the Department of Ophthalmology, College of Physicians and Surgeons of Columbia University, New York City, USA.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001284:Atrophy; D001808:Blood Vessels / Q000473:pathology; D002829:Choroid / Q000473:pathology; D003103:Coloboma / Q000150:complications* / Q000473:pathology; D005260:Female; D006801:Humans; D006984:Hypertrophy; D007223:Infant; D007231:Infant, Newborn; D007511:Ischemia / Q000150:complications; D008297:Male; D008875:Middle Aged; D009457:Neuroglia / Q000473:pathology; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D010857:Pigment Epithelium of Eye / Q000473:pathology; D012160:Retina / Q000473:pathology; D012163:Retinal Detachment / Q000209:etiology* / Q000517:prevention & control; D012167:Retinal Perforations / Q000150:complications / Q000209:etiology; D012171:Retinal Vessels; D012590:Sclera / Q000473:pathology; D014603:Uveal Diseases / Q000150:complications* / Q000473:pathology