Biomedical subjects
Publications and source records attributed to R R Hirons.
The prosthesis required for a child with a transverse deficiency whilst a simple version of that appropriate for the adult follows the same principles. The child with a longitudinal deficiency may require an extension, or orthoprosthesis and this may be combined with surgical reconstruction. The principles, technique of measurement and fabrication methods using both traditional and modern composites are described.
Eighteen adults with night vision complaints showed significantly increased/final rod thresholds as compared to their age- and sex-matched controls. Vitamin A and zinc levels did not differ between the two groups. Vitamin A supplementation of three subjects produced changes in final rod thresholds and serum vitamin A levels. These changes did not produce subjective improvements in night vision.
The oculocardiac reflex (OCR), which may result from traction or pressure on the globe, orbital contents, or extra ocular muscles, has been associated with cardiac arrests during ocular surgery. The pathways for this reflex have been established and several preventive methods including retrobulbar block and intravenous injection of atropine have been developed. These procedures, combined with recent advances in anesthesia, may have reduced the occurrence of fatal cardiac arrests caused by the elicitation of the reflex during ocular surgery, however, for numerous reasons, the reflex remains of optometric interest.
Previous work, conducted under laboratory conditions, has shown that biofeedback using infrared eye position monitoring can be used to successfully treat strabismus. For the present study, seven matched pairs of strabismic patients were selected. One member of each pair received biofeedback enhanced vision therapy while the other member received traditional vision therapy. Cover test data obtained during each training session showed an advantage in using biofeedback enhanced training in several but not all cases. It is suggested that the optimum use of biofeedback may be prior to traditional training rather than integrated with it.
To examine the reliability of VER data, responses were obtained from 9 normal subjects. For steady state and transient displays, 7 consecutive VERs were obtained using 10, 25, 50, 75 and 100 ensemble averaged 384 ms activity samples each. Data from the 7 VERs were averaged by considering the first 3, the first 5, and all 7 VERs. For each display, maximum reliability was obtained by averaging at least 5 VERs with each consisting of 50 or more ensemble averaged samples. The steady state display produced more reliable data than did the transient display, but when each display system was used in a refraction format, the transient display produced refractions with narrower uncertainty ranges.