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Refraction and axial eye dimensions, evaluated by ultrasound measurements, were investigated in 101 pre-term infants and 25 full-term controls. Gestational ages in the pre-term group ranged from 25 to 34 weeks, birth weights from 728 to 2480 g. All were seen in the eye clinic due to risk of developing retinopathy of prematurity. Age at examination was 36-54 weeks (gestational/conceptional) in the pre-terms and 37.3-50 weeks in the term infants. Adjusted to a 40 weeks axial length value (based on an assumed average eye elongation of 0.14 mm per week) the term-values were similar, 17.02 and 17.03 mm in the two groups. Within the premature group, however, the 40-week adjusted axial lengths were shorter, the shorter the gestational age. The study demonstrated more foetal anterior segment proportions, with flatter anterior chambers and thicker, more spheroid lenses in the preterm infants. Probably this explains the early preponderance of myopia in that group, at feature eventually to disappear, and not to be confused with myopia of prematurity. As compared to the full-terms a correlational disturbance by pre-term delivery was further indicated by the absence of the usual correlation between axial length and refractive value.

Visual evoked potentials (VEPs) were studied in a patient who developed visual impairment during ethambutol treatment. The ERG and the flash VEP were normal at the time of maximal visual loss, whereas pattern reversal VEPs 2 and 5 months after onset revealed evidence of severe bilateral optic nerve involvement, especially affecting macular fibres. Seven months after onset paramacular PNP complexes with a late positivity (scotomatous response) were recorded after pattern reversal and half-field stimulation, suggesting involvement of fibres subserving central vision. At the time when visual acuity was normal there was still electrophysiological evidence of a mild involvement of the anterior visual pathway. The papillomacular bundle seems to be especially involved in ethambutol eye toxicity.