The child's vision and its measurement. Comparative results of different tests of visual acuity in children as a function of age

The authors describe a new test for determining the visual acuity in pre-school children. It is a picture-test which is composed by pictures of animals of varying sizes, the child being asked to name them in turn. The six pictures (duck, rabbit, cock, elephant, fish, and butterfly) with an homogeneous density, can be utilized according to several manners-appariement or verbal expression--and several distances: 2,50 m or 5 m. That test gave good results on children aged from three years upwards, however the performances could be increased by prectising exercises.     

Repeatability of the phenol-red thread and tear thinning time tests for tear film function

Reliable tear function tests are required both in clinical practice and for research. Between-sessions repeatability of the phenol-red thread and tear thinning time tests was assessed for 17 young normal Caucasian subjects on two consecutive days. A single phenol-red thread result and the mean of three tear thinning times were recorded on each day. The minimum phenol-red thread result was 11 mm, and the 68 per cent and 95 per cent confidence intervals for repeatability were ± 5 mm and ± 10 mm, respectively. We propose diagnostic criteria of less than 11 mm for low tear secretion and less than 16 mm for a borderline result, based on the 68 per cent confidence interval. A level of measurement effect on repeatability of tear thinning time was present (Spearman's rho = 0.79, p = 0.002), with longer times showing greater variability: this relationship was eliminated by logarithmic data transformation. The tear thinning time test was not sufficiently reliable for clinical use; for a result of 15 seconds, there was 95 per cent confidence that subsequent times would lie between 57 and three seconds. We recommend further investigation into the use of log scales for tear stability tests.     

Accommodation dynamics as a function of age

Experiments are described in which the dynamic accommodation response to a stimulus whose vergence was varying sinusoidally with time between 1.33 and 2.38 D was measured as a function of frequency for 19 subjects, with ages distributed between 18 and 49 years. Response to abrupt stimulus change between the same levels was also measured. The results showed that at any age, for the sinusoidal stimuli, gain fell with frequency and phase lag increased: at fixed frequency, gain fell with age and phase lag increased. Neither reaction nor response times for step stimuli changed with age. Analysis of the sinusoidal data suggests the possible existence of a cut-off frequency of about 2 Hz, which varies little with age and above which the system cannot respond. The phase data is compatible with the existence of a frequency-independent time delay, which increases with age from about 0.17 s at 20 years to 0.48 s at 40 years. The results are discussed in terms of current knowledge of the factors contributing to the development of presbyopia.     

Residual hydrogen peroxide as a function of platinum disc age.

Recently there has been considerable attention given to the possible deleterious effects of residual hydrogen peroxide on both the cornea and the crystalline lens of the eye. We measured residual hydrogen peroxide levels of the AOSept disinfection system at regular intervals over a 4 month period. By 1 month the residual hydrogen peroxide level was 21 ppm +/- 9.4 (mean +/- standard deviation); at the end of 2 months it was 36 ppm +/- 17.6. At 3 months, when disc replacement is recommended, the residual hydrogen peroxide level was 43 ppm +/- 4.7 (range: 17-98 ppm). At 4 months the residual hydrogen peroxide level rose to a mean of 48 ppm +/- 18.2. The increase in measured residual hydrogen peroxide between month 1 and each successive month was found to be statistically significant. However, these levels failed to induce an increase in symptomatology or slit lamp findings. As determined by scanning electron microscopy there was an erosion of the platinum coating with time that appeared to coincide with the measured residual peroxide level. Cultures of randomly selected platinum discs at the end of 4 months failed to reveal more than isolated positive findings of Staphylococcus epidermidis. While an increase in residual peroxide with time may lead to greater disinfecting capabilities of this system, the possibility of corneal damage as a direct result of high peroxide levels is of concern.     

Psychophysical studies of monkey vision. I. Macaque luminosity and color vision tests

Macaque monkeys and normal human observers were tested on the same apparatus for the presence of a Purkinje shift, and for spectral sensitivity under scotopic and photopic conditions. The flicker fusion point for different lights was used as a measure of visual sensitivity in these tests and the testing procedure was a four-alternative forced choice. The results show that macaque monkeys and normal human observers show a rod-cone break at the same flicker frequency, and are very similar in both relative and absolute scotopic and photopic sensitivity.Macaque monkeys, normal human observers and color-defective human observers were also tested under identical conditions in several measures of color vision.     

Ocular component data in schoolchildren as a function of age and gender.

PURPOSE: To describe the refractive error and ocular components of a large group of school-aged children as a function of age and gender. METHODS: In this report, we describe the refractive error and ocular components of 2583 school-aged children (49.3% girls, overall mean [+/-SD] age 10.0 +/- 2.3). Measurement methods included cycloplegic autorefraction, autokeratometry, videophakometry, and A-scan ultrasonography. For statistical comparisons across gender and age, a critical point of alpha = 0.005 was used to assess significance because of the large sample size and the large number of comparisons made. RESULTS: Of these 2583 children, 10.1% were myopic (-0.75 D or more myopia in both meridians), and 8.6% were hyperopic (+1.25 D or more hyperopia in both meridians). As would be expected, there was a significant effect of age on refractive error (spherical equivalent, p < 0.0001), toward less hyperopia/more myopia. There was no significant difference in the average refractive error between girls and boys (p = 0.0192). Girls had steeper corneas than boys (0.74 D steeper in the vertical meridian and 0.63 D steeper in the horizontal meridian, p < 0.0001). There were no significant differences in corneal power with age (p = 0.16). Both older age and male gender were significantly associated with deeper anterior chambers (p < 0.0001 for both). The crystalline lens showed significant thinning with age (p < 0.0001), however, there was no significant difference in the lens thickness between girls and boys (p = 0.66). Both Gullstrand lens power and calculated lens power showed significant effects of age and gender (p < 0.0001 for both). Girls, on average, had Gullstrand lens powers that were 0.28 D steeper and calculated lens powers that were 0.80 D more powerful than boys. Axial length also showed significant effects of age and gender (p < 0.0001 for both). Girls' eyes were, on average, 0.32 mm shorter than those of boys. CONCLUSIONS: These cross-sectional data show a general pattern of ocular growth, no change in corneal power, and crystalline lens thinning and flattening between the ages of 6 and 14 years. Girls tended to have steeper corneas, stronger crystalline lenses, and shorter eyes compared with boys.     

Comparison of the standard and Adams desaturated D-15 tests with congenital colour vision deficiencies

The Adams desaturated D-15 was designed to be administered to patients with acquired colour vision defects by simply reducing the chroma of the Munsell colours by 2 for each cap in the test. In this study, the performance of the Adams desat D-15 in the assessment of congenital colour vision deficiencies is evaluated. The standard D-15 and Adams desat D-15 tests were administered to 75 congenital red-green colour deficient subjects who had been diagnosed on the basis of their performance on the Nagel anomaloscope Mark 1. The results were analysed in terms of the directions, extent and specificity of errors and compared with the diagnosis on the Nagel anomaloscope. Of the 13 colour-deficient subjects who made no errors on the standard D-15, 1 failed the Adams desat D-15 and 2 made single crossings. No colour-deficient subject who failed the standard D-15 made anything less than a simple inversion of adjacent caps on the Adams desat D-15. The Adams desat D-15 did not perform as well as the standard D-15 in identification of the type of defect in dichromats. On the basis of these data, it is predicted that about 5% of dichromats will be mis-classified by the Adams desat D-15 whilst under 0.1% will be mis-classified by the standard D-15. However, with the anomalous trichomats, more crossings were made on the Adams desat D-15, particularly by the milder anomals, and a diagnosis was possible in more cases. Where a diagnosis was possible, it was also correct more often with the Adams desat D-15.(ABSTRACT TRUNCATED AT 250 WORDS)     

Contrast sensitivity function as a diagnostic tool in low vision

In this case report, a patient's visual loss associated with both cataract and senile macular degeneration is described. The contrast sensitivity function (CSF) as well as Retinometer and Visometer findings indicate that the additional visual loss over a year's time was lenticular, rather than retinal, in origin.     

Repeatability of visual acuity testing using a psychometric function

Purpose

To evaluate the repeatability of a new method of measurement of visual acuity by use of a psychometric function.

Methods

The visual acuity of 15 healthy adults was measured by use of a psychometric function (PFVA) and by use of a conventional method using a decimal visual acuity chart (DeVA). We performed two tests. To evaluate intra-rater reliability, a tester measured the visual acuity three times for each subject, and the intraclass correlation coefficients, ICC (1,1), were calculated for PFVA and DeVA. Next, to evaluate inter-rater reliability, three testers measured the visual acuity for one subject, and the ICC (2,1) were calculated for PFVA and DeVA. The PFVA and DeVA of five subjects with ocular diseases were also measured.

Results

In the evaluation of intra-rater reliability, the ICC (1,1) of the DeVA was 0.83 and the ICC (1,1) of the PFVA was 0.95. In the evaluation of inter-rater reliability, the ICC (2,1) of the DeVA was 0.88 and the ICC (2,1) of the PFVA was 0.93. In both tests the standard deviations of the PFVA were significantly lower than those of the DeVA. For four of the five subjects with ocular diseases, the PFVA was significantly improved by treatment.

Conclusion

The repeatability of our method is better than that of the conventional method using a decimal visual acuity chart.     

Infant vision screening predicts failures on motor and cognitive tests up to school age

In a population-based infant vision screening programme, 5295 infants were screened and those with significant refractive errors were followed up. To assess the relationship between the development of vision and other domains, we report a longitudinal study comparing infants with significant hyperopia, identified at age 9 months ('hyperopes') with infants with normal refractions ('controls'). Children are included who completed at each age a broad set of visual, cognitive, motor and language measures taken over a series of follow-up visits up to age 5.5 years. Hyperopes performed significantly worse than controls on the Atkinson Battery of Child Development for Examining Functional Vision at 14 months and 3.5 years and the Henderson Movement Assessment Battery for Children at 3.5 and 5.5 years. The Griffiths Child Development Scales, MacArthur Communicative Development Inventory and British Picture Vocabulary Scales showed no significant differences. Exclusion of those infants who became amblyopic and strabismic did not substantially alter these results, suggesting that the differences between groups were not a consequence of these disorders. These results indicate that early hyperopia is associated with a range of developmental deficits that persist at least to age 5.5 years. These effects are concentrated in visuocognitive and visuomotor domains rather than the linguistic domain.     

Macular electroretinogram as a function of age of subjects

Macular and paramacular electroretinograms in response to two adjacent checks (6 deg/side), alternating at constant mean luminance, were recorded in 34 normal subjects ranging in age from 16 to 74 years. The macular electroretinogram declines progressively in amplitude with age (R = –0.42; P = 0.013). The amplitude ratio between macular and paramacular responses tends to be independent of age (R = -0.21; P = 0.22).Age-related changes in the macular electroretinogram shown in our study are consistent with previous anatomical and functional studies, which indicate a deterioration of photoreceptors beyond 20 years of age. These results suggest a possible use of this technique for future studies on macular degeneration.     

Incorporation of glutamic acid into soluble protein as a function of age.

The incorporation of U-14C glutamic acid into soluble bovine and human lens protein fractions has been studied as a function of age. Culture technique and DEAE cellulose fractionation has been used. In bovine lenses the incorporation of glutamic acid into alpha and gamma crystallins decreased with age whereas in the beta crystallin group the specific activities remained constant. All protein fractions of the human lenses showed a gradual reduction of the incorporation of the radioactive amino acid between 40 and 74 years of age. The highest specific activity was found to correspond to Spector's HL protein and its existence is confirmed throughout the whole human life-span.     

Repeatability of the C‐100 colour vision test

Background: The C‐100 colour vision test has been shown to have a high validity for diagnosing the type of red‐green colour vision defect, however, there is little information on the repeatability of the test. This study examines the repeatability of the C‐100 in classifying the colour vision defect as either protan or deutan. Methods: The C‐100 was administered on two occasions to 58 subjects with congenital red‐green colour vision defects: The sessions were separated by a minimum period of 10 days. Results: The repeatability of the C‐100 was high with a kappa coefficient of agreement for diagnosis of 0.96. The few discrepancies were misclassifying protans as deutans. Conclusion: The C‐100 is a highly repeatable test in terms of separating protans from deutans. However, if a discrepancy occurs, it is more likely to be a protan misclassified as a deutan rather than vice versa.     

Quantitative scoring of panel tests for assessment of colour vision in age related maculopathy

Using the Farnsworth dichotomous D15 test and the Farnsworth-Munsell 100-hue test, Bowman compared the colour discrimination of subjects having age related maculopathy to that of age matched normals. In this paper a quantitative assessment of Bowman's results was obtained using the colour difference vector analysis of Vingrys and King-Smith. The assessment indicates that there is selective blue-yellow loss in age related maculopathy and that the FM 100-hue test is more useful than the D15 test in distinguishing between normal subjects and those with early age related maculopathy. We suggest that the vector method of analysis is particularly useful in clinical trials and in monitoring changes of colour vision over time.     

Monochromatic aberrations as a function of age, from childhood to advanced age

PURPOSE: To describe monochromatic optical aberrations of the eye as a function of age. METHODS: One hundred fourteen subjects with a spherical equivalent within +/-3.50 D from emmetropia, corrected visual acuity of 20/40 or better, and normal findings in an ophthalmic examination were enrolled. The mean age was 43.2 +/- 24.5 years (range, 5.7-82.3). Monochromatic optical aberrations were measured with a Hartmann-Shack wavefront sensor after pharmacological dilation and cycloplegia. RESULTS: For a 5-mm pupil and for third- to seventh-, third-, fourth-, and fifth- to seventh-order aberrations, as well as for coma and spherical aberrations, the root mean square (RMS) error as a function of age was modeled by a second-order polynomial regression. It decreased progressively through childhood, adolescence, and early adulthood; reached a minimum level during the fourth decade of life, then increased progressively with age, to age 82. For a 5-mm pupil, the mean modulation transfer function (MTF) was reduced in both the child-teenage (5-20 years; n = 29) and the elderly (61-82 years; n = 37) groups versus the middle-aged adult group (41-60 years; n = 24; P < 0.05). In young adults (21-40 years; n = 23) and elderly subjects, the MTF curves were very close and almost superimposed at spatial frequencies higher than 38 cyc/deg. CONCLUSIONS: Aberrations of the whole eye were objectively measured from early childhood to an advanced age, and the relationship between monochromatic aberrations and age has been shown to fit a quadratic model. The results suggest that the definition of emmetropization should be broadened to include the reduction of higher order aberrations.     

The foveal point spread function as a determinant for detail vision

A point spread function, chosen to link contrast sensitivity and stimulus dimensions, can be obtained from measured thresholds by assuming small-signal-linearity and peak detection for the visual system. To that end a special case of summation of subthreshold signals (perturbation) is used, taking specific measures against the effect of sensitivity drift. The basic assumptions are tested simultaneously and confirmed. Other provisional assumptions like radial symmetry and homogeneity were evaluated along a horizontal and a vertical meridian through the fovea. In the fovea no deviation from radial symmetry was found. The effect of inhomogeneity within the central fovea. seems to be too small to cause a significant change in the point spread function. The validity for predicting thresholds of stimuli exposing larger areas is tested. Annuli with varying radii show no significant aberration if probability summation is taken into account. Predicted disk thresholds, however, show a large discrepancy with experiment for radii larger than 2 min arc. A possible extension of the model with multiple-detection units having tuned sizes is evaluated.