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Biomedical subjects

R A Weale

Publications and source records attributed to R A Weale.

139 records · Page 8Linked to original sources
PubMedDate not supplied

Presbyopia - a maverick of human aging.

The aim of this study was to examine the extent to which the age-related variations of properties of the human lens may be able to account for presbyopia. Dimensionless linear regressions were calculated for age-related biological functions with special reference to ocular and lenticular ones. Their intercepts on the x-(age-)axis are compared, and their distribution is analyzed. An analysis was made of the effect of the growth of the lens on the relation between its shape and the proximal zonular anchorages on the one hand and the age-related variation of the angle between the zonule and the equatorial plane of the lens. The lens is not unusual in seeming to have evolved in support of a life-span of about 120 years. Presbyopia, however, fails to fit into the general picture and this is hypothesized to result from lenticular growth and a combination of factors which are not all governed by senescence. The potential involvement of the root of the iris throws an interesting light on the apparently worldwide variation of the condition.

Journal Article↗
PubMedDate not supplied

On the age-related prevalence of anisometropia.

Data on the prevalence of non-amblyopic anisometropia amongst adults throughout the world were tabulated and plotted as a function of age. The global picture reveals a systematic rise in the prevalence of anisometropia with age, the fitted linear regression having a significant positive slope of 1% (p < 0.0005) for every 7 years. The distribution may embrace a juvenile rise and a later, post-presbyopic one, perhaps due to neuro-senescence.

Adolescent↗
PubMedDate not supplied

Ethnic variability of the vasculature of the optic disc in normal and in glaucomatous eyes.

PURPOSE: Although disc pallor is associated with glaucoma, the structural macro-anatomy of the disc vasculature has received little attention, and possible ethnic differences have not been considered. Accordingly we studied the distribution of blood vessels crossing the rim of the optic disc. METHODS: Thirty normal controls, and 50 glaucomatous cases with a unilaterally impaired visual field were studied. The sample populations included white Caucasian, and African and Afro/Caribbean volunteers. A b/w photographic method of imaging the blood vessels crossing the rim of the optic disc was used, the illuminant being green. The prints used in the analysis had been masked during their exposure to enhance contrast. The numbers of vessels, grouped into large (approximately 60nm), medium (approximately 30nm), and small (approximately 10nm) lumina, were counted, the disc images being divided radially into eight equal sectors. RESULTS: While the large vessels crossed the rim mainly along the vertical, the small ones did so mainly in the horizontal. The distribution of the medium vessels was unpolarized but their crossings predominated on the nasal side. The vessel patterns differed significantly between the two ethnic groups as regards both number and distribution along the rim of the disc, the smaller vessels being more numerous in Caucasian eyes (p approximately 0.02). Rim crossings by vessels were smaller in glaucomatous eyes in both ethnic groups. In normal eyes there was a statistically significant age-related decline in the number of small vessels after the age of 20 years. CONCLUSIONS: There exists a statistically significant inverse relation between the number of capillaries crossing the disc rim and the vertical cup/disc ratio. Caucasian rims show the larger number of capillaries crossing.

Adolescent↗