Spectral absorption coefficient measured in situ in the North Sea with a marine radiometric spectrometer system.

A submersible marine radiometric spectrometer system, capable of simultaneous measurements of the in situ spectral and angular properties of the underwater oceanic light field, is used to determine spectral inherent optical properties of marine waters. The inversion methods used to convert the sampled light field measurements into estimates of spectral absorption are presented and sample results for three water types obtained during a cruise in the North Sea are given.

Can retinoscopy be used to screen infants for amblyopia? A longitudinal study of refraction in the first year of life.

One hundred normal babies were refracted by two observers in a double-masked study within 24 hours of delivery and 30 minutes after instillation of 1% cyclopentolate. The procedure was repeated at 6 weeks, 3 months, 6 months and 1 year. At birth agreement between the two refractionists to within 1 dioptre spherical equivalent was 82%, rising to 94% at 1 year. Astigmatism of greater than 1 dioptre increased from 10% at birth to 42% at 6 months but decreased to 15% at 1 year. Myopia was uncommon (4%) but 80% of eyes were hypermetropic more than +2 dioptres and 25% more than +4 dioptres at birth, although these percentages decreased to 5% and 3% at 1 year. Anisometropia of more than 1 dioptre between the two eyes was uncommon but in the two cases where it persisted in the presence of high hypermetropia, reversible amblyopia was encountered in both cases.

Visual assessment of infants: vernier targets for the Catford drum.

Targets comprising a horizontal black line 5' thick offset by 1' were printed on strips to stick to the drums of the Catford Visual Acuity Apparatus. The 'vernier' targets so produced corresponded to the different sizes of Snellen letters from 6/6 to 2/60 when presented at 50 cm. Twenty-five children between the ages of 3 and 12 years with known amblyopia (mostly strabismic) were tested in a double blind trial to compare the visibility of the vernier targets with subjective Snellen acuity. All vernier results, both for better and amblyopic eye, were within one line of Snellen acuity. One hundred and twenty normal preverbal infants with normal eyes under the age of 2 1/2 years were tested with the vernier strips. Normal infants under the age of 6 months recorded a vision of 6/60-2/60; normal infants aged 6 to 12 months recorded 6/24-6/36, and infants between the ages of 1 and 2 1/2 years recorded 6/12-6/18.