Two siblings of normal intelligence, belonging to a nonconsanguineous marriage, had their conditions diagnosed as mucopolysaccharidosis (MPS) type IV—the so-called Morquio syndrome. Despite corneal cloudiness, no other ophthalmological abnormalities or complaints emerged, the visual acuity, fields, and color vision being normal. The electroretinogram, recorded during dark adaptation, pointed to slight photopic impairment, and its amplitudes were normal in the one and supernormal in the other case. The psychophysical dark adaptation also indicates some scotopic impairment. In view of the normal electrooculogram, the scotopic deficiency should be located in the inner retina. Conduction in the optic pathways and the information processing in the striate cortex examined by the visual evoked potential were normal. No ophthalmological and electrophysiological deficiencies have been found in other members of the family, including the carrier.
Abraham FA, Yatziv S, Russell A, Auerbach E. A Family With Two Siblings Affected by Morquio Syndrome (MPS IV): Electrophysiological and Psychophysical Findings in the Visual System. Arch Ophthalmol. 1974;91(4):265–269. doi:https://doi.org/10.1001/archopht.1974.03900060275005
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