ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01169.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A more scientific method than the Snellen chart for determining visual acuity is imperative for research studies and is desirable in many clinical situations. The psychometric method using the constant contour interaction S‐chart of Flom has been regarded as an accurate and reliable visual acuity measure and has been used widely for research purposes. This paper compares visual acuity measured by the S‐chart with that measured by the Snellen and Bailey‐Lovie charts. The results indicate that the Baily‐Lovie chart is a valid, reliable and rapid method of measuring threshold visual acuity for research p

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01170.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A set of near Bailey‐Lovie logMAR letter charts that varied in contrast from 0.40 dB (C = 0.95) to 58.0 dB (C=0.001) were used to measure the middle and high spatial frequency range of the contrast sensitivity function (CSF) of 15 subjects with age‐related maculopathy (ARM) and 15 age‐matched normal subjects. The letter charts were shown to have good test‐retest reliability. Compared with measures made using CRT generated square wave gratings of variable contrast and spatial frequency they were also shown to provide a valid measure of CSF in the mid to high spatial frequency range. The 20.0 dB letter chart alone was shown to be a good screening device for macular disease. The letter charts do not provide a measure of the peak of the CSF and a supplementary test of contrast sensitivity is needed to quantify contrast sensitivity at a low spatial frequency. Three measures are proposed as necessary to document foveal visual capability of patients with macular disease: distance logMAR visual acuity to measure high spatial frequency resolution, visual acuity with letter charts of 20 dB contrast to assess mid spatial frequency resolution; and contrast sensitivity for the detection of an edge to estimate contrast sensitivity for larger

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01171.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Ever since it was first reported that the contrast sensitivity for low spatial frequency sinusoidal gratings falls off with a slope approximating unity it has been suggested that this may represent gradient detection by a single spatial filter tuned to higher spatial frequencies. We have further investigated this possibility using aperiodic as well as periodic stimuli. Experiments are presented that involve manipulations of luminance, field size and spatial adaptation, and the results are consistent with a multiple filter model accounting for the detection of low spatial frequency (0.2‐2 c/deg) periodic and aperiodic stimul

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01172.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A longitudinal study of stereoacuity levels of 859 children at 7 years, 811 children at 9 years and 796 children at 11 years was conducted using the TNO random dot stereotest. The prevalence of defective stereoscopic vision was found to be between 2.1 and 3.2 per cent. A further 10–16 per cent of children had only moderate stereoacuity levels when compared with their peers. The stereoacuity levels achieved by most of the children improved with age, but the rand order correlations for the stereoacuity levels between ages 7 and 9, and ages 9 and 11, were small. Defective stereopsis and poor stereoacuity levels were clearly associated with manifest strabismus and problems of visual acuity, and if failure to pass the quantitative plates was a cut‐off point for screening purposes most of the children with visual problems would have been identif

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01173.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The data for this paper were collected during a two‐year study of the elderly in the market town of Melton Mowbray. The data show that typically, persons aged 75 years and older have poor uncorrected vision (6/36 Snellen acuity), but good corrected acuity, 73.8 per cent gaining 6/12 binocular Snellen acuity or better. Over 88 per cent were able to read N8 typesize or better, under test conditions. Those with low uncorrected vision were the most likely to possess spectacle

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01174.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The data for this paper were collected during a two‐year study of the elderly in the market town of Melton Mowbray. The randomly selected subjects, aged 76 years of age and older, were found to be on average + 1.33 D hypermetropic and the average cylinder power was 0.82 D. The mean refractive error was found to be + 1.5 D with 0.5 negative cylinder at between 85 and 90 degrees. Of all the subjects, 30 per cent had significant anisometropi

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

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

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01176.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

This paper reviews recent developments in the field of progressive addition spectacle lenses and variable focus lens systems design. The study is a sequel to the previous analytical work of von Rohr (1916), Graham (1942), and Bennett (1970). A brief history of the work documented by the aforementioned authors is presented. Comparative assessment is undertaken of the most recent patents of progressive addition and variables focus spectacle lenses. A largely verbal description is employed because patent literature is often devoid of mathematical models.

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01177.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Time‐of‐day variations were studied both in tonic accomodation and in tonic vergence. Thirty‐six male volunteers were measured once in the morning and at one other time on the same day. The mean baseline value of tonic accomodation was 2.02 D. Time‐of‐day variations were found, with a late evening measure being + 0.6 D greater than the morning value. No independent time‐of‐day fluctuations were found in tonic vergence. Post‐hoc analysis, however, showed that tonic vergence tended to shift in the same direction as an individual's tonic accommodation during the afternoon. During the evening, tonic vergences tended to shift oppositely to toni

ISSN:0275-5408    

DOI:10.1111/j.1475-1313.1988.tb01178.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY