Biomedical subjects

D B Elliott

Publications and source records attributed to D B Elliott.

58 records · Page 4Linked to original sources

PubMed1988

The use of accurate visual acuity measurements in clinical anti-cataract formulation trials.

A standardized visual acuity technique is presented for use in anti-cataract drug trials. Ferris Logmar charts were used in repeatability studies of vision, visual acuity and pinhole visual acuity measurements for twenty normal subjects (mean (+/- SD) age 64 +/- 6.3 years). Visual acuity measurements were shown to be the most repeatable and thought to be the most suitable for monitoring cataract progression. Repeated visual acuity measurements were made on 29 cataractous eyes of 15 subjects (mean (+/- SD) age 67.8 +/- 7.2 years). A Logmar score change of 0.1 (one line) was shown to be a statistically significant change. This value can be used in statistical analyses of drug efficacy. The normal data gives a mean Logmar visual acuity of 1.15 (Snellen equivalent 6/5). This indicates the inadequacy of using 6/6 as a norm value for visual acuity, even for older patients. As the possibility of reversal of cataract theoretically exists in the early stages of cortical and capsular cataracts, patients with small amounts of these types of cataract are ideal patients for anti-cataract formulation trials. The normal visual acuity results indicate that the inclusion criteria for clinical trials can include patients with cataracts with visual acuity as good as 6/6.

Aged↗

PubMed1987

Contrast sensitivity decline with ageing: a neural or optical phenomenon?

Previous studies of contrast sensitivity changes with age have produced conflicting results. Most recent reports indicate that, with increasing age, contrast sensitivity at medium and high spatial frequencies decreases. Whether this is caused by reduced retinal illumination due to senile pupillary miosis and increased lens absorption, by the greater light scatter of the aged eye or by retinal and neural cell loss and degeneration is also in doubt. We measured the contrast sensitivity functions of 16 young (mean age 21.5 +/- 2.7 years) and 16 older (mean age 72 +/- 4.3 years) subjects with normal healthy eyes, using a modified Rodenstock retinometer and a monitor-based computer system. The former method bypasses the effects of the optical media to measure the contrast sensitivity function of the retinal and neural system alone, while the latter measures the contrast sensitivity function of the whole visual system, including media. The results show the older group to have significantly lower contrast sensitivity at medium (4 c deg-1, p less than 0.1) and high (10.6 c deg-1, p less than 0.001; 16.5 c deg-1, p less than 0.001) spatial frequencies. They also suggest that this is due primarily to retinal and neural changes with age, with optical factors having a slight effect at the highest spatial frequency only.

Adult↗

PubMedDate not supplied

Changes in macular function throughout adulthood.

Recent reports suggest that the neural system is the principal cause of loss of visual function with age and that senile lenticular and pupillary changes are of minor importance. In order to investigate this neural deterioration further we measured Logmar visual acuity and photostress recovery time (PSRT) in 61 subjects over an age range of 19 to 78 years. The magnitude of the PSRT reflects the efficiency with which the visual system recovers from exposure to a glare source and is principally dependent upon the integrity of the photoreceptors and the retinal pigment epithelium. The results indicate that macular function declines significantly throughout adulthood.

Adult↗

PubMedDate not supplied

Visual function one year after excimer laser photorefractive keratectomy.

BACKGROUND: The purpose of this study is to investigate retrospectively the visual function of eyes 1 year after photorefractive keratectomy. METHODS: Visual function was assessed in 34 eyes of 22 patients who had undergone excimer laser surgery (Summit Excimed UV200). The mean time after surgery was 12.3 months. Twenty eyes of 20 age-matched normal subjects served as controls. The following tests were used: high and low contrast logMAR visual acuity, Pelli-Robson contrast sensitivity, and straylightmeter scores at 3.5 degrees and 10 degrees. RESULTS: There was a significant difference between scores obtained for the photorefractive keratectomy population and the control (p < .001, ANOVA). Fifty-six percent (18/32) of the excimer treated eyes fell outside the 95% confidence limits of the normal data in at least one test of visual function; 22% (7/32) fell outside in at least 3 out of 5 tests. CONCLUSIONS: Some eyes showed reduced visual function 1 year after excimer surgery compared to age-matched normal controls. These deficits can only be detected fully when psychophysical tests in addition to visual acuity are employed.

Adult↗