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Contrast Sensitivity Versus Visual Acuity in Retinal Disease

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Contrast Sensitivity Versus Visual Acuity in Retinal Disease Br J Ophthalmol: first published as 10.1136/bjo.70.7.553 on 1 July 1986. Downloaded from British Journal of Ophthalmology, 1986, 70, 553-559 Contrast sensitivity versus visual acuity in retinal disease MICHAEL F MARMOR From the Division of Ophthalmology, Stanford University, and the Ophthalmology Section, Veterans Administration Medical Center, Palo Alto, CA, USA SUMMARY A large group of individuals with retinal disease were tested prospectively for contrast sensitivity by means of Arden gratings. A subgroup of 19 were also tested with the Nicolet automated television system. Individuals with macular or peripheral dystrophy showed a general reduction in contrast sensitivity as visual acuity decreased. The loss of contrast sensitivity was more prominent for high spatial frequencies (6.4 cycles per degree) than for low ones (0-2 cycles per degree). Similar results were obtained for patients with achromatopsia and congenital stationary night blindness. Patients with functional complaints, but no organic basis for decreased acuity, showed greater scatter in their test scores. The Nicolet results showed somewhat smoother curves, but were no more specific in separating normality from abnormality. Contrast sensitivity testing was not specific for the retinal disease entities considered, but may be useful in recording a degree of retinal damage and a degree of functional visual disability. Contrast sensitivity appeared to be reduced whenever acuity was reduced, so that a distinction could be made between patients having a loss of contrast beyond the expectations for their level of acuity and those in whom a loss of contrast simply corroborates the reduction of acuity. http://bjo.bmj.com/ Snellen visual acuity testing is a relatively crude index gratings on a large group of patients and on a of visual function, in so far as it measures resolution subgroup with the Nicolet television system. only with high contrast targets, since objects in the real world exhibit varying degrees of contrast and a Material and methods varying content of spatial frequencies. There has been considerable interest in recent years in develop- Over a two-year period all patients referred for on September 24, 2021 by guest. Protected copyright. ing practical clinical tests for contrast sensitivity. clinical visual electrophysiological testing at the Several systems are now commercially available, Stanford University Medical Center were given the including a set of printed plates,'2 a computerised Arden grating test. All testing was performed by a television system,3 and a set of posters.4 Reports have single examiner, who followed the technique of appeared showing that contrast sensitivity deficits out Arden et al."2 Each grating was covered with a sheet of proportion to visual acuity may be found in of grey paper that was slowly removed, exposing patients with retinal or optic nerve disease.2"'' There progressively higher levels of contrast. The six verti- have been no large series published, however, to cal sinusoidal gratings (numbered 2-7) have spatial show the incidence of contrast sensitivity defects in frequencies of 0-2, 0-4, 0-8, 1-6, 3-2, and 6-4 cycles macular or retinal disease, or to show whether the per degree (cpd) respectively. Marginal numbers pattern of loss has diagnostic or prognostic value. range from 0 at the low contrast end to 20 at the high There is also little information on what levels of contrast end; a score of 25 is assigned arbitrarily if the contrast deficit to expect simply on the basis of subject is unable to perceive the grating. decreased acuity. The present study shows the result For a period of three months we had use of an of prospective contrast sensitivity testing with Arden Optronix 2000 contrast sensitivity test system, Correspondence to Michael F Marmor, MD, Division of Ophthal- courtesy of Nicolet Instrument Company. We pro- mology, Stanford University Medical Center, Stanford, CA 94305, grammed this system to mimic the Arden test pro- USA. tocol: gratings of 0-5, 1.5, 3.0, and 5 71 cpd were 553 Br J Ophthalmol: first published as 10.1136/bjo.70.7.553 on 1 July 1986. Downloaded from 554 Michael FMarmor presented MACULAR DYSTROPHY by the 'method of increasing contrast', 150 which requires the observer to push a button when the grating first becomes visible. The pattern was presented four times at each spatial frequency. 130 _ We have tabulated data from subjects who fit into several major diagnostic categories. 'Normals' were 110 1I 16 persons aged 10-33 with 20/20 acuity, no symp- * SW" toms, and no evidence of ocular disease; most of them were unaffected family members of patients 90 _ h*" | S *0_ with disease. Patients with 'macular dystrophy' (n= some 50), aged 6-76, included with Stargardt's SCORES disease, Best's vitelliform dystrophy, and patients 700air ; * * * ~TOTAL with unclassified bilateral maculopathy that could not 900~~~3* .8 be ascribed to infectious, degenerative, or other L)~50 ~ ~ 3 secondary causes. Patients with 'diffuse dystrophy' (n=61, ages 6-66) include those with retinitis pig- ,,2050 _-t* mentosa and its variants, as well as unclassified conditions in which there was bilateral diffuse retinal damage noted by ERG or fundus examination, and 15 - _ e 0 0 no evidence for an acquired aetiology. Specifically * excluded from this group are carriers of X-linked lo so * m LT 2 retinitis pigmentosa, individuals with mild or 'de- limited' forms of retinitis pigmentosa," and patients < 10 - _* PLATE NO. 2- with predominantly cone or central dystrophies. S 0 Patients with achromatopsia (n=6, ages 10-34) and II I IllI 25 0-00. -a- congenital stationary night blindness (n=7, ages r-*-* emj.-Itqft-o .JB -w- -*--I 8-47) were classified on the basis of ERGs that showed an absence of cone or rod function respec- tively, and had histories and physical findings consis- 20 tent with stationary congenital disease. Patients with *0 0 0 S. U 'functional complaints' (n= 19, ages 8-66) had visual * *.. S U http://bjo.bmj.com/ symptoms that could not be substantiated * * S by physical 15 [_ U e * 0 findings. * " PLATE NO. 7 Snellen visual acuities were tested with a conven- tional clinical projection system using the subjects' 4. I best known correction. However, many of the sub- 10 l . jects were referred for . only electrophysiological 15 20 30 50 70 100 200 400 CF testing, and the accuracy of their refraction was not VISUAL ACUITY (20/...) on September 24, 2021 by guest. Protected copyright. confirmed. Fig. 1 Ardengratingscoresfrom eyes with macular dystrophy. The data areplotted against a logarithmic scale of Results visualacuity. Top: Total scores. Middle: Scores on plate number2 (0.2 cpd). Bottom: Scores on plate number 7 (6-4 Arden grating scores for normal subjects (one eye cpd). only) with 20/20 vision were close to Arden's values. ' The total score (sum of all six gratings) averaged The middle and bottom parts of Fig. 2 show scores 65 0±6-8 (standard deviation). Despite the manual from the coarsest (0-2 cpd) and finest (6.4 cpd) technique for unmasking the gratings, Arden scores gratings respectively. All of the eyes with macular were remarkably consistent. Four patients with stable dystrophy could perceive the coarse grating, but a disease had repeat testing at intervals between 7 and significant number of eyes could not appreciate the 21 months, and their total scores did not vary more finest grating (scores of 25) even though acuity was than 10%. excellent. Fig. 1 shows data from all eyes with macular Similar results were obtained from patients with dystrophy. The total Arden grating scores (top) diffuse dystrophies (Fig. 2). generally increased as visual acuity decreased, Fig. 3 shows the results from patients with achro- although a wide range oftotal scores are evident even matopsia and congenital stationary night blindness among those eyes with good acuity (20/40 or better). (CSNB), both non-progressive disorders of retinal Br J Ophthalmol: first published as 10.1136/bjo.70.7.553 on 1 July 1986. Downloaded from Contrast sensitivity versus visual acuity in retinal disease 555 DIFFUSE DYSTROPHY * CNSB oACHROMATOPSIA 150r - . *- 150 so 130 F- 0: 130 8 0 8 0 110 110 0 00 :}: } 90 [ 0 90_ 0 *.S* 0~~~~~* 0 0 * 0 70 7Q- g 1 TOTAL SCORES 50 5020_ TOTAL SCORES _ I I @0~~~~~~~~~ 25 0 0~~~~~~~~~~~ 0 X 20 LLJLU 15 _ 0 LU c: S cc 0 *_ * * co 2 2) 2 * 0 U 0 S *0 0 OD * "-lS *W * 0 w 15 cc 10 0 _ 0 1 * PLATE NO. 2 0 ""-m < m e m 10 U 25 0 oO *~ 0 * * PLATE NO. 2 I s I 20 25 http://bjo.bmj.com/ I a m- . * 15 20 _ 25 0 e S * PLATE NO. 7 10 _ 15 _ I I I I ml - 15 20 30 50 70 100 200 400 CF VISUAL ACUITY (20/...) on September 24, 2021 by guest. Protected copyright. U U * PLATE NO.7 _ 10 Fig. 3 Arden gratingscoresfor eyes with achromatopsia * S (0) and congenitalstationary night blindness (0), presented lI lI as in Fig. 1. 15 20 30 50 70 100 200 400 CF VISUAL ACUITY (20/ ... to increase as visual acuity decreased (with the Fig. 2 Arden gratingscoresfrom eyes with diffuse exception of two questionably low scores in a patient dystrophy, presented as in Fig. 1. who tested at 20/70 acuity), but the scatter was more pronounced and less predictable for each individual function. The total scores generally correlated with grating. the levels of acuity in these subjects. All subjects Fig. 5 compares results obtained with Arden perceived the coarsest grating, but those with reduced gratings with those obtained with the Nicolet unit at acuity could not perceive the finest one.
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