Many elderly patients have eye-drops prescribed. We have examined the abilities in eye drop application of 43 consecutive outpatients aged 75 years or more who completed a questionnaire and demonstrated their technique in eye-drop application. Less than one-third of patients applied drops themselves, the rest relying on others; one-third of this group lived alone. The majority of patients experienced some difficulty with the application of their drops and it was estimated that half of those who usually applied their own treatment were unlikely to succeed in instilling a drop into the conjunctival sac. Few patients had been prescribed aids or appliances to improve their eye-drop application technique.

PURPOSE. To investigate the longitudinal change in horizontal and vertical ocular alignment in normal and prism-reared infant monkeys during the critical developmental period. METHODS. Ocular alignment was measured using Hirschberg photographic methods in 6 infant monkeys reared under prism-viewing from day 1 after birth to 4 months, and 2 monkeys reared with normal visual experience. Photographs were acquired twice a week for the first 6 months of life and analyzed to identify pupil center and the first Purkinje image from which eye positions and strabismus angle were calculated. RESULTS. At 3 weeks after birth, prism monkeys presented with significant horizontal ocular misalignment. A gradual change in alignment was seen in all prism-reared monkeys stabilizing at approximately 11 weeks, at which time 5 monkeys were exotropic (mean, 16°XT; range, 13°-24°) and 1 monkey was esotropic (5°ET). A reduction in ocular misalignment was observed after exposure to normal visual environment at 16 weeks, but at 34 weeks of age, that is, 18 weeks after removal of prisms, prism-reared monkeys displayed a mean horizontal strabismus of 7°XT (range, 2°ET to 20°XT), which was still significantly different from normal monkeys. CONCLUSIONS. Prism-rearing disrupts binocular fusion mechanisms, and horizontal and vertical strabismus is seen to develop as early as 3 weeks of age in monkey models, equivalent to approximately 3 months in humans. The time course of change in alignment overlaps with disruption in various visual sensory functions, suggesting a causal temporal link between sensory and motor mechanisms for alignment.