Author Affiliations: Departments of Ophthalmology and Neuroscience, University of Minnesota, Minneapolis.
Birth defects affect the health and development of children, particularly because concomitant lifelong disabilities can ensue. Anophthalmia and microphthalmia, birth defects that are important causes of childhood blindness, have a national prevalence of 1.87 per 10 000 live births, and an estimated 780 cases occur annually in the United States.1 Clinical care for patients with congenital anophthalmia and severe microphthalmia frequently requires surgical reconstruction to restore orbital size and placement of orbital implants,2 which are secured by their attachment to the extraocular muscles (EOMs). Thus, if the EOMs are functional, orbital implants can provide movement of and a more natural appearance for the prosthesis. In the study by Bohnsack et al3 in this issue of the Archives, the magnetic resonance imaging results of 3 patients demonstrate the spectrum of the morphologic characteristics of EOMs observed in patients with anophthalmia and severe microphthalmia. These results range from an essentially normal configuration (despite the near absence of the globe) to undetectable muscle tissue. The reason for these significant differences is not understood and cannot be predicted based on the ultimate phenotype of the EOMs. Bohnsack et al3 investigated the potential basis for these differences by comparing the timing of eye loss with the formation of the EOMs, using molecular biological and classical embryologic tools in zebrafish and chick embryos. Although this approach may seem unconventional, combining the clinical observation of variable formation of the EOMs in patients with anophthalmia with a basic-science experimental approach directed at answering questions raised by the observations proved to be quite powerful.
McLoon LK. What Experimental Embryology Can Teach Us About the Development of the Extraocular Muscles in AnophthalmiaAt the Interface of Basic and Clinical Sciences. Arch Ophthalmol. 2011;129(8):1077-1079. doi:10.1001/archophthalmol.2011.187