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Show ,. Clin. Neuro-ophthalmol. 5: 281-282, 1985 ~ 1985 Raven Press, New York Neuro-anatomical Feature Photo The Pop Eye Phenomenon: An Extreme Form of the Oculodigital Phenomenon AHMAD M. MANSOUR, M.D. ROBERT D. REINECKE, M.D.t Leberl reported an interesting observation that children with congenital retinal degeneration may press and rub their fingers against their eyes. Franceschetti2.3 encountered this finding in other forms of congenital blindness (espedally congenital cataract) and gave it the name of oculodigital phenomenon. An extreme form was encountered in this 4year old boy with bilateral choristoma of the cornea and conjunctiva (Fig. 1). He had proptosed his eyeballs since the age of 8 months. This peculiar voluntary luxation of the eyes can be called the pop eye phenomenon. It is seen in some animals with retractor bulbi muscles and in deep-sea fishes with stalked eyes.4- 6 The oculodigital sign is explained on the basis of generation of phosphenes. Pressing on the eyeball creates entoptic phenomena in the form of luminous patterns (phosphenes),7 which result hom direct stimulation of the retina. In the pop eye phenomenon, traction on the optic nerve by luxation of the globe amplifies the deep-pressure phosphenes generated by the retina and creates new entoptic patterns. From the American University of Beirut Medical Center (A.M.M.), Lebanon, and Wills Eye Hospital (R.D.R.), Phil· adelphia, PA, U.S.A. Writt for rtprints to: A. Mansour, M.D., 502 E. Melbourne Ave, Silver Spring, MD 20901, U.S.A. December 1985 Figure 1. Bilateral severe proptosis of eyeballs in a boy with choristomatous growth over the epibulbar area. The fingers are deeply inserted into the superior orbital roofs. Both orbits appear shallow by computed tomographic scan. Shallow orbits could explain the proptosis of the eyeballs in patients with the oculodigital phenomenon. 281 The Pop Eye Phenomenon References 1. Leber, T.: Die Krankheiten der Netzhaut und des Sehnerven. Handb. Augenheilk. Cefe Saemisch 5: 633, 1877. Cited in Beard, c., et aI., eds. Congenita/ anomalies of the eye. St. Louis: C.V. Mosby, 1968; p. 453. 2. Franceschetti, A.: Rubeole pendant la grossesse et cataracte congenitale chez I'enfant, accompagnee du phenomene digito-oculaire. Ophtha/m% gica 114: 332-339, 1947. 3. Roy, F. H.: Ocular autostimulation. Am. ,. Ophtha/mo/. 63: 1776-1777, 1967. 282 4. Duke Elder, S.: System of ophthalmology, Vol 1. London: H. Kimpton, 1958: 495-497. 5. Whitnall, S. E.: An instance of the retractor bulbi muscle in man. J. Anat. Physiol. 46: 36-40, 1911. 6. Munz, F., and McFarland, W.: Evolutionary adaptations of fishes to photic environment. In Crescitelli, F., ed. The visual system in vertebrates. Handbook of sensory physiology, Vol 7. Berlin: Springer-Verlag, 1977: 128, part 5. 7. Tyler, C. W.: Some new entoptic phenomena. Vis. Res. 18: 1633-1639, 1978. Journal of Clinical Neuro-ophthalmology |
