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Biomedical subjects

D L Mayer

Publications and source records attributed to D L Mayer.

6 recordsLinked to original sources
PubMed1992

Preferential looking--clinical lessons.

Preferential looking-based tests of acuity have been available for over a decade. The authors discuss their use in clinical practice, particularly in three groups in whom acuity could not be quantified by traditional means: normal infants, and young children who are either mentally retarded, or who have visual disorders. Preferential looking (PL) testing has increased our understanding of the natural history of visual pathway disorders and has revealed certain patterns of acuity development. Early acuity development may be normal, delayed, or stationary, while in later infancy and childhood the following abnormal patterns have been identified: asymptotic, parallel, catch-up, or regressing. While this information has introduced a degree of complexity hitherto unknown which, if misunderstood, can lead to test misinterpretation, it offers the clinician invaluable information to improve patient care, and may also offer clues to the fundamental mechanisms of visual development.

Child, Preschool↗
PubMed1991

Visual development of infants with severe ocular disorders.

Among 11 patients who presented as blind in early infancy, with Leber's congenital amaurosis (5 patients), optic nerve hypoplasia (4 patients), or macular colobomata (2 patients), 8 developed visually guided behavior and measurable grating acuity by age 5 to 46 months. All children with measurable grating acuity demonstrated visually guided mobility. Grating acuity was predictive of later visual performance in 10 of 11 patients by age 12 to 16 months. The best grating acuity attained by 7 months was 1.3 to 3.0 cycles/degrees (20/460 to 20/200) and 0.13 cycles/degrees (20/4700) by month 8. Two patients with Leber's congenital amaurosis and one with optic nerve hypoplasia remained blind. No clinical features existed to differentiate these three patients from the eight whose visual status improved. Posterior visual pathway maturation may underlie the improvement.

Child↗
PubMed1990

Modified Allen pictures to assess amblyopia in young children.

To produce a test of visual acuity for young children that is more sensitive to amblyopia than current preschool vision tests, the authors surrounded four Allen pictures with "crowding" bars. This modified Allen test was evaluated by measuring acuity of amblyopic children (n = 28) and children (n = 10) and adults (n = 5) with normal eyes. Mean acuities of amblyopic eyes for the modified pictures was 0.8 octaves or nearly three logMar Snellen lines poorer than for the isolated pictures. For nonamblyopic and normal eyes modified picture acuity averaged 0.1 to 0.4 octaves poorer than isolated picture acuity. Average acuities of amblyopic eyes (n = 22) for the modified pictures agreed with line letter acuities. These results suggest that the modified picture test induces contour interaction similar to that of line letter tests, and thus, is a more sensitive test of amblyopia in the preschool child than isolated symbols.

Adolescent↗
PubMed1978

Astigmatism and acuity in two primate infants.

The development of grating acuity was followed in two astigmatic primate infants, one a human being and one a pigtail macaque monkey. Both infants showed variations of acuity with grating orientation, predictable from the orientation and type of astigmatism present. Optical correction of the human infant during testing virtually eliminated the variation of acuity with orientation, suggesting that a neurally based meridional amblyopia had not yet been established.

Age Factors↗
PubMedDate not supplied

Assessment of vision and amblyopia by preferential looking tests after early surgery for unilateral congenital cataracts.

Preferential looking tests obtained over the first 3 years were used to evaluate the development of visual acuity of 21 patients who underwent surgery for unilateral congenital cataracts and fitting of contact lenses before age 6 months. Mean acuity of the aphakic eyes improved rapidly in the first year; however, between the end of the first year and the end of the third year there was no improvement in mean aphakic acuity. Consistent with this, the percentage of patients who were amblyopic by the criterion interocular difference in acuity (IOD) of 0.5 octaves (oct) or greater was 94% at the first test age near the onset of occlusion therapy, decreased to 72% at the end of year 1, and increased to 89% by the end of year 3. Variations in occlusion therapy appear to account for these results: mean hours of occlusion per day were 6.2 in year 1, 4.4 in year 2, and 2.7 hours in year 3. Furthermore, the IOD at age 1 year was negatively correlated with hours of occlusion in the first year and the IOD at age 3 years was negatively correlated with cumulated hours of occlusion over all 3 years. That is, the less the amount of occlusion therapy, the greater the IOD. The patients' ages at time of surgery did not account for any further variance in these results than that accounted for by occlusion therapy. This study demonstrates that PL acuity measurement can aid in monitoring the response to occlusion therapy of infants with deprivation amblyopia due to unilateral congenital cataracts.

Amblyopia↗