Biomedical subjects
Publications and source records attributed to R A Schachar.
To understand the mechanism and cause of accommodation and presbyopia, the sclera in the region of the ciliary body of presbyopic patients was expanded. The amplitude of accommodation was increased in all presbyopic patients. A unique hypothesis of accommodation based on increased zonular tension is presented, which when applied clinically, results in a treatment for presbyopia.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In the past two years, 216 implantations have been performed with a minimum of a three-month follow-up; visual acuity was better than 20/40 in 89% of cases.
Explore the source record for details and available documents.
The illusion generated by a "pincushion grid" is not predicted from the two-dimensional Fourier transform of the grid. This implies that the visual system may not perform two-dimensional Fourier transforms of observed patterns.
Intact bovine lenses have been studied using the polarized Raman spectroscopic technique. A brief theoretical and experimental review of Raman spectroscopy is presented. From the dependence of the Raman depolarization ratio on the propagation direction of the incident radiation we have determined that the uniaxial qualities of the lens result from microscopic anisotropy and have established the quantitative positional correlation of specific chemical bonds with respect to the lens optic axis. In particular, the hydrogen bonded linear CONH groups of the antiparallel beta-pleated sheet are preferentially oriented in directions orthogonal to the lens optic axis. The Raman spectra of intact lenses do not exhibit bands at positions characteristic of either the alpha-helix or the random coil protein structure. The antiparallel beta-pleated sheet protein microstructure and the lens fiber cross-sectional macrostructure exhibit a remarkable similarity. This similarity may be causal and is consistent with the protein concentration of the lens, the birefringent properties observed by both Lenhard and Brewster, the CONH bond angle distribution with respect to the optic axis, and the lens anatomy. It is suggested that cortical cataracts are caused by fluctuations in protein orientational order.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.