Investigative ophthalmology & visual science
-
Invest. Ophthalmol. Vis. Sci. · Aug 2010
Use of single-vision distance spectacles improves landing control during step descent in well-adapted multifocal lens-wearers.
Epidemiologic research has shown that multifocal spectacle wearers (bifocal and progressive addition lenses [PALs]) are more than twice as likely to fall than are nonmultifocal spectacle wearers, with this risk further increasing when negotiating stairs. The present study investigated whether step and stair descent safety is improved by using single-vision distance lenses. ⋯ Use of single-vision distance spectacles led to improvements in landing control, consistent with individuals' being more certain regarding the precise height of the lower floor level. This enhanced control was attributed to having a view of the foot, step edge, and immediate floor area that was not blurred, magnified, or doubled and that did not suffer from image jump or peripheral distortions. These findings provide further evidence that use of single-vision distance lenses in everyday locomotion may be advantageous for elderly multifocal wearers who have a high risk of falling.
-
Invest. Ophthalmol. Vis. Sci. · Aug 2010
ABCA4 and ROM1: implications for modification of the PRPH2-associated macular dystrophy phenotype.
To identify the causative mutation leading to autosomal dominant macular dystrophy, cone dystrophy, and cone-rod dystrophy in a five-generation family and to explain the high intrafamilial phenotypic variation by identifying possible modifier genes. ⋯ Features of a PRPH2-associated phenotype might be modulated by additional mutations in other genes (in this family ABCA4 and/or ROM1) accounting for intrafamilial variability and resulting in a cumulative effect worsening the phenotype. Families showing a variable macular dystrophy phenotype caused by mutations in PRPH2 should be tested for additional mutations in ABCA4 and ROM1, as they may alter the progression of the PRPH2 phenotype. This testing will influence genetic counseling, as patients with additional mutations may be confronted with a faster progression of visual loss.
-
Invest. Ophthalmol. Vis. Sci. · Aug 2010
Cold-sensitive corneal afferents respond to a variety of ocular stimuli central to tear production: implications for dry eye disease.
To investigate the response characteristics of the corneal afferents that detect ocular conditions critical to the activation of the "afferent limb" of the lacrimation reflex. ⋯ These results demonstrate that innocuous "cold" cornea thermoreceptors are activated by drying of the ocular surface and hyperosmotic solutions, conditions that are consistent with a role in tear production. The authors hypothesize that the dysfunction of these corneal afferents and the lacrimation reflex pathway they activate lead to some forms of dry eye disease.