Biomedical subjects

J A M Jennings

Publications and source records attributed to J A M Jennings.

4 recordsLinked to original sources

PubMed2006

Longitudinal changes in peripheral refraction with age.

The changes in the patterns of refraction (skiagrams) over the central +/-35 degrees of the horizontal field of 3 originally near-emmetropic eyes of 2 subjects were determined over a time interval of 26 years. The subjects were aged 32 and 40 years at the time of the first measurements. The central refractions shifted in the expected hyperopic direction, while the radial and tangential image fields in the periphery became more myopic. These longitudinal results agree with recent transverse studies, provided that allowance is made for the change in central refraction: the reported loss with age in peripheral visual performance does not seem to be attributable to markedly increased peripheral astigmatism.

Adult↗

PubMed2005

Distance vergence adaptation is abnormal in subjects with convergence insufficiency.

It is well known that in convergence insufficiency (CI) prism adaptation is reduced in response to base-out (BO) prisms at near. There have also been some suggestions in the literature that adaptation is reduced at other distances as well. The present data show that in CI adaptation is not only reduced in response to BO at near, but also in response to base-in (BI) at near and for both BI and BO at distance. This raises the interesting question whether distance adaptation becomes reduced because of reduced near adaptation or whether these subjects have a generally reduced horizontal adaptation mechanism.

Adaptation, Ocular↗

PubMed2005

Increasing the proportion of binocular vision makes horizontal prism adaptation complete.

In previous phoria adaptation experiments on normal subjects adaptation tends to reach only approximately 2/3 of the prism-induced phoria while clinical experience indicates that prism adaptation is usually complete. The present data show that increasing the proportion of binocular experience through the phoria-inducing prism allows adaptation to become complete. Longer periods of binocular vision give a better indication of vergence adaptation function. This is particularly important in experiments where normal and abnormal adaptive abilities are being compared.

Adaptation, Ocular↗

PubMed2005

Horizontal and vertical prism adaptation are different mechanisms.

As part of a study on subjects with convergence insufficiency (CI), their vertical and horizontal vergence adaptation was assessed and compared with age matched controls in order to investigate whether the horizontal adaptation system can be regarded as being independent of the vertical adaptation system. Using a flashed Maddox rod technique horizontal vergence adaptation was found to be reduced in CI subjects whereas no difference could be found in vertical adaptation. These results confirm that the vertical and horizontal adaptation systems can be treated as independent mechanisms.

Adaptation, Ocular↗