Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545213
Title: The effect of intraocular scattered light on the contrast sensitivity function
Author: Griffiths, Stella N.
ISNI:       0000 0001 3520 7384
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1986
Availability of Full Text:
Access from EThOS:
Access from Institution:
Abstract:
Intraocular light scatter is high in certain subject groups eg the elderly, due to increased optical media turbidity, which scatters and attenuates light travelling towards the retina. This causes reduced retinal contrast especially in the presence of glare light. Such subjects have depressed Contrast Sensitivity Functions (CSF). Currently available clinical tests do not effectively reflect this visual disability. Intraocular light scatter may be quantified by measuring the CSF with and without glare light and calculating Light Scatter Factors (LSF). To record the CSF on clinically available equipment (Nicolet CS2000), several psychophysical measurement techniques were investigated, and the 60 sec Method of Increasing Contrast was selected as the most appropriate. It was hypothesised that intraocular light scatter due to particles of different dimensions could be identified by glare sources at wide (30°) and narrow (3.5°) angles. CSFs andLSFs were determined for: (i) Subjects in young, intermediate and old age groups. (ii) Subjects during recovery from large amounts of induced corneal oedema. (iii) A clinical sample of contact lens (CL) wearers with a group of matched controls. The CSF was attenuated at all measured spatial frequencies with the intermediate and old group compared to the young group. High LSF values were found only in the old group (over 60 years). It was concluded that CSF attenuation in the intermediate group was due to reduced pupil size, media absorption and/or neural factors. In the old group, the additional factor was high intraocular light scatter levels of lenticular origin. The rate of reduction of the LSF for the 3.5° glare angle was steeper than that for the 30° angle, following induced corneal oedema. This supported the hypothesis, as it was anticipated that epithelial oedema would recover more rapidly than stromal oedema. CSFs and LSFs were markedly abnormal in the CL wearers. The analytical details and the value of these investigative techniques in contact lens research are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.545213  DOI: Not available
Keywords: Optometry
Share: