Francis A. Young

THE TRANSMISSION OF REFRACTIVE ERRORS WITHIN ESKIMO FAMILIES

ABSTRACT A study was carried out on volunteer Eskimo families at Barrow, Alaska. The total population consisted of 508 subjects with complete information including a clinical examination as well as refractions with and without cycloplegics. Correlations between refractive errors of parents and children as well as between siblings are determined on 41 family units comprising 197 subjects. The correlations between parents and children were not significantly different from zero, whereas the correlations between siblings were high and significant. These results were interpreted to suggest that there is no major hereditary component involved in development of myopic refractions among the offspring while there is a strong environmental component operating to create the sibling correlations. These interpretations are supported by the fact that there is virtually no myopia among the grandparents or parents but approximately 58% of the offspring are myopic.

The effects of pilocarpine and neostigmine on the blood flow through the anterior uvea in monkeys. A study with radioactively labelled microspheres

15 μm microspheres labelled with 85Sr were used to determine the rate of blood flow through the various parts of the eye in monkeys. Pilocarpine or neostigmine had been applied on the cornea of one eye while the other eye served as control. Both pilocarpine and neostigmine increased blood flow through the iris, the ciliary processes and the ciliary muscle by 100–200%, while the blood flow through the choroid and the retina was unchanged. Atropine, but not hexamethonium, abolished the effect of neostigmine. The results suggest that the increase in blood flow is mediated through vascular muscarinic receptors.

Bifocal Control Of Myopia

&NA; Forty‐three native American bifocal wearers grouped by yearly age levels from 9 to 15 with a mixed group of 6 to 8 year olds are matched on beginning age, sex, beginning refractive error and ending age with 83 Native American control subjects. Similarly 226 Caucasian bifocal wearers are matched on the same criteria against 192 control subjects. Although the comparisons are made on each age group, the average annual rate of progression for the bifocal Native American subjects is ‐0.12 and ‐0.10 diopters in the right and left eyes respectively against a comparable rate of progression of ‐0.38 and ‐0.36 diopters for the control subjects. These differences are significant but not as significant as those found on the Caucasian subjects of ‐0.02 and ‐0.03 diopters right and left eyes against ‐0.53 and ‐0.52 diopters for the controls.

THE DISTRIBUTION OF REFRACTIVE ERRORS IN MONKEYS.

The refractive errors of 1000 rhesus monkeys ( Macaca mulatta ) and 100 pig-tailed monkeys ( Macaca nemestrina ) were determined by retinoscopy while the animals were under phencyclidine hydrochloride (Sernyl or Sernylan) anesthesia and cyclopentolate hydrochloride (Cyclogyl) cycloplegic. The rhesus population contained 642 females and 358 males and ranged in age from 8 months to 20 years. The pig-tailed monkeys comprised 69 females and 31 males ranging in age from 12 months to 15 years. Approximately one-third of each group were laboratory-born, with known ages. The ages of the other animals were estimated through the use of regression equations based on the age-weight relationship in the laboratory-born monkeys. Three hundred of the rhesus monkeys had been in captivity for less than 10 weeks. The refractive errors were analyzed and plotted by species, sex, age and by wild and laboratory groups. The mean and median refractive errors were found to be significantly more hypermetropic in the rhesus monkeys and among the younger age groups and wild animals and more myopic in the pig-tailed monkeys and among the older age groups and laboratory animals. The females showed a higher per cent of myopia in the 1- to 3-year-old groups, over all, and in the groups with myopia in excess of 6 diopters. The distribution of refractive errors in monkeys was compared with two distributions of refractive errors in humans. The monkey distribution fell midway between the human distributions and was similar in all essential characteristics.

Refractive errors, reading performance, and school achievement among Eskimo children.

ABSTRACT The relationship between refractive errors and various measures of reading and school achievement on the entire school population of Eskimo children at Barrow, Alaska, are presented. Comparisons are made with the Caucasian population of school children at Pullman, Washington.

values, Personality, Physical Characteristics, and Refractive Error*

&NA; A questionnaire containing: (a) a questionnaire of physical characteristics associated with psychosomatic symptoms, (b) questions to determine the presence of myopia or hypermetropia but not the amount of error, (c) a shortened version of the Gough Adjective Check List, and (d) the Heist and Yonge Omnibus Personality Inventory were administered to 782 introductory psychology students attending Washington State University. This group consisted of 297 self‐identified myopes (117 males, 180 females), 439 emmetropes (207 males, 232 females), and 46 hypermetropes (15 males, 31 females). Results indicated that myopes and nonmyopes differed from one another with respect to their value systems, personality, and physical characteristics as assessed by the components of the questionnaire. Differences in these characteristics were consistently found by all assessment techniques to exist most often between myopes and hypermetropes and between emmetropes and hypermetropes rather than between myopes and emmetropes. In general myopes exhibited a personality pattern of introversion, whereas hypermetropes maintained a pattern described as extroverted.

The psychological differentiation of male myopes and nonmyopes.

&NA; A comparison of 140 male myopes and 118 male nonmyopes of the entering class of Virginia Military Institute cadets in 1968 demonstrated that there are a number of Strong Vocational Interest Inventory test items which will clearly differentiate myopes from nonmyopes so that it is possible to identify 76% of the individuals falling into either class on the basis of a stepwise discriminant analysis based almost entirely on the Strong Vocational Interest Blank. The items which discriminate in favor of the myopes are essentially those which require academic achievement and individual creative performance, whereas the items which are in favor of the nonmyopes are those which require business and selling skills as well as outdoor types of activities. Further, the myopes are significantly more likely to achieve officer status and win more academic awards than the nonmyopes.

Comparison of cycloplegic and non-cycloplegic refractions of Eskimos.

&NA; A cycloplegic and non‐cycloplegic refraction was obtained on 946 eyes of 213 male subjects and 291 female Eskimos between 6 and 88 years old. When the results obtained are compared with those obtained on white subjects by Bannon, good agreement is found between the two studies in the case of the hypermetropic subjects but relatively poor agreement is found for the myopic subjects. Bannon found approximately 38% of his myopic cases showing less myopia under cycloplegia whereas the present study found 75% of the myopia subjects showing less myopia under cycloplegia. The Barrow population shows an exceptionally high proportion of myopes in the age group between 11 and 26 with approximately 60% being myopic with a high degree of myopia. It is possible that these Eskimo subjects are in such a strong spasm of accommodation that it is not possible to reduce the spasm by means of any type of fogging technique. Thus, when the subjects are put under cycloplegia, there will be a considerable decrease in the amount of myopia resulting from a reduction of the spasm.

THE INHERITANCE OF OCULAR COMPONENTS

&NA; This paper represents the analysis of the components of refraction across seventy‐one Eskimo families consisting of thirty, first generation or grandparents, forty‐one, second generation or parents and 258 generic children. Both husbands and wives are included in the first and second generations. The results indicate that the initial size and component relationships within the one‐two year old eye are probably inherited along with high hypermetropia and corneal power in older children and adults. There is no evidence that any of the other components are inherited.

Four years of annual studies of chimpanzee vision.

&NA; Four annual studies of the visual ocular components of approximately 40 male and 40 female chimpanzees are summarized and discussed. In general, ocular changes over the five‐year span are similar to those found in human subjects under similar conditions except for changes in the corneas, which show changes not usually found in humans. Approximately a third of the subjects show increased axial lengths and myopia. Females show higher levels of myopia than males.