Correcting lens system for perimetry.

A lens system to correct for both refractive error and perimeter test distance is frequently needed for accurate perimetry. Patients often lack appropriate near vision corrections and full aperture trial case lenses, when they are available, barely cover the central 30 degrees and hence frequently produce lens rim artefacts. A special system of correction lenses has been developed for perimetry which overcomes these problems. This system is head mounted, being based upon the Essilor presbyopia demonstration set, and is suitable for use with most perimeters.

Facial characteristics in children with Down's syndrome and spectacle fitting.

Significant refractive error is very common among children with Down's syndrome so the requirement for spectacles for this group is high. The aim of this study was to measure the facial characteristics of children with Down's syndrome and to compare them with two previous studies which have aided the design of children's spectacle frames. The study was carried out in two schools in South Wales, measuring 20 children between the ages of 3.6 and 14.4 years. The results show that between the ages of 7 and 14 years, facial characteristics of children with Down's syndrome do not change with age and rarely coincide with those of other children, either of a similar age or younger. Thus children with Down's syndrome cannot be fitted satisfactorily with conventional children's frames, and it would be desirable for a specially designed range of frames to be made available.

Sensitivity of the cornea after exposure to ultraviolet light.

Corneal sensitivity was measured before and after exposure to an electric welding arc. The ultraviolet radiation produced in the exposed eye a rapid and large decrease in corneal sensitivity with an equally rapid recovery, all occurring within 4 h. The other eye serving as a control retained the same sensitivity throughout the same period of time.