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Biomedical subjects

H Obstfeld

Publications and source records attributed to H Obstfeld.

8 recordsLinked to original sources
PubMed1991

Weight of edged spectacle lenses.

Uncut spectacle lenses of various powers and materials were edged to three different eye shapes and three box eye sizes. Their weights were measured. This demonstrated that the eye shape has very little effect on the weight of edged lenses and that there is very little difference in weight for neighbouring eye sizes. The density of the lens material is of major importance, but other characteristics also influence the edged lens weight.

Eyeglasses↗
PubMed1989

Crystalline lens accommodation and anterior chamber depth.

Using paraxial equations, the change in dioptric power of the crystalline lens required to image objects at given distances from the eye, on the retina, is calculated. This shows that the depth of the anterior chamber affects crystalline lens accommodation more than other variables. The relationship between anterior chamber depth and presbyopia, and a possible geographical aspect, are discussed.

Accommodation, Ocular↗
PubMed1989

Anthropometry for children's spectacle frames.

Facial measurements of 154 Caucasian children aged 5-14 were taken, to provide statistical information for spectacle frame manufacturers. The main differences compared with adult measurements were in the following dimensions: temple width, head width, bridge height, projection, splay angle and front to bend. The range of the 'distance between rims' measurement of adults, was similar to that of children. A number of differences between this group and a small group of Afro-Caribbean children was encountered.

Adolescent↗
PubMed1986

The effect of prismatic spectacle and contact lens corrections on ocular rotation.

The effect of prismatic spectacle corrections on ocular rotation for different object distances is determined and evaluated. The same principles are applied for a correction fitted on the eye, that is, a contact lens correction. The latter must be considered as a thick lens system. The effects of different types of prismatic contact lenses on ocular rotation are considered. Assuming the contact lens to remain stationary and the eye behind the lens to rotate, it is shown that the theoretical effect on ocular rotation of prismatic contact lenses is practically equal to their prismatic effect in air. The effect for high-powered contact lenses is discussed.

Contact Lenses↗