2020–2021 BCSC Basic and Clinical Science Course™
8 External Disease and Cornea
Chapter 8: Systemic Disorders With Corneal and Other Anterior Segment Manifestations
Skeletal and Connective Tissue Disorders
Many musculoskeletal and connective tissue diseases affect the cornea. The corneal manifestations of these diseases are outlined in Table 8-5.
Ehlers-Danlos syndrome (EDS), a heterogeneous group of diseases, is characterized by hyperextensibility of joints and skin, tendency to bruise easily, and formation of “cigarette paper” scars.
There are more than 20 known types of EDS, which are classified as autosomal dominant, autosomal recessive, or X-linked recessive. Multiple genetic loci have been identified. Specific defects occur in collagen type I and III synthesis; lysyl hydroxylase deficiency may occur as well.
Table 8-5 Skeletal and Connective Tissue Disorders of Interest to the Ophthalmologist
Ehlers-Danlos syndrome type VI (EDS VI), or the ocular–scoliotic type, is autosomal recessive and associated with only moderate joint and skin extensibility, brittle cornea easily ruptured upon minor trauma, blue sclera, keratoconus and keratoglobus, and severe scoliosis. Type VIA shows lysyl hydroxylase deficiency, but type VIB shows normal production of lysyl hydroxylase.
Traditionally, clinical diagnosis of EDS VI is confirmed by an insufficiency of hydroxylysine on analysis of hydrolyzed dermis and/or reduced enzyme activity in cultured skin fibroblasts. However, the diagnosis can also be confirmed by an altered urinary ratio of lysyl pyridinoline to hydroxylysyl pyridinoline, which is characteristic of EDS VI.
Recognition of EDS VI is essential. In addition, the clinician must be aware of the syndrome’s association with mitral valve prolapse, spontaneous bowel rupture, and strabismus surgery complications, as well as the potential to confuse the brittle cornea with injury due to child abuse. Use of patch grafts for repair of corneoscleral ruptures has been successful. Genetic counseling should be considered.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.