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Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms

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Sensitivities in Older Eyes with Good Acuity: Cross-Sectional Norms Sensitivities in Older Eyes With Good Acuity: Cross-Sectional Norms Alvin Eisner,*f Susan A. Fleming,*! Michael L. Kleins and W. Manning Mauldinf We measured several indices of foveal visual function for a large group of people aged 60 and older. The data reported in this paper are from individuals who had good acuity in each eye and met a number of other criteria for good ocular health. For each index, we described the rate of cross-sectional change with age using linear regression statistics. We found age-related change for eyes having 20/20 or better acuity to exist for several different indices. Sensitivity mediated by the blue-sensitive cones decreased with age, as expected. However, the rate of decrease was faster for females than for males. At least part of the difference was associated with different rates of lenticular change. Absolute sensitivity at long wavelengths also decreased with age, but at the same rate for each sex. Rayleigh color matches changed with age in a manner consistent with underlying age-related decreases of effective foveal cone photopigment density. However, not all indices showed age-dependent changes. For instance, the time constant describing the rate of photopic dark adaptation did not appear to change with age. Invest Ophthalmol Vis Sci 28:1824-1831, 1987 Human visual function changes with age. Cross- criteria for good ocular health in each eye. In particu- sectional age-related changes have been reported for lar, we have tested people having good acuity in each Snellen acuity,1 spatial2"4 and temporal4 contrast sen- eye. Macular change that can be observed fundu- sitivity, short-term adaptational dynamics,5-6 sensitiv- scopically is limited to the presence of drusen and/or ity at absolute threshold,7-8 color discrimination910 pigmentary change. and many other functions. However, few studies doc- The functional tests that we chose to use were umenting age-related functional change have tested among those likely to be especially sensitive to the many individuals older than age 60. Typically, only integrity of both the retinal pigment epithelium enough older individuals are tested to demonstrate (RPE) itself and the RPE/photoreceptor interface. that young and old people differ statistically for a We measured blue-sensitive ("S") cone mediated sen- given visual function." Thus, age-related functional sitivities, rates of photopic dark adaptation, and Ray- changes within the older age group remain largely leigh color matches. We measured S cone sensitivities unknown. For this reason, we have measured several because, in accordance with Kollner's rule, S cones different kinds of foveal sensitivity in a large popula- may be especially vulnerable to retinal insult, particu- tion of people aged 60 and older. larly at the level of the RPE.12 We calculated time By measuring different kinds of sensitivity in a constants of photopic dark adaptation rates because large older population, we have attempted to estab- those rates depend on the rate of photopigment re- lish sets of cross-sectional norms. Because many peo- generation,13 which in turn depends on the health of ple older than age 60 have ocular pathology, we have the RPE.1415 In calculating time constants, we mea- tested only people meeting a number of necessary sured absolute threshold at long wavelengths, where preretinal absorption is minimal.1617 We measured Rayleigh color matches for both small and large fields because Rayleigh matches depend on the ratio of L to From the *Neurological Sciences Institute and the tDepartment M cone quantum absorption, which varies systemati- of Ophthalmology, Good Samaritan Hospital and Medical Center, 1819 Portland, Oregon, and the ^Department of Ophthalmology, Ore- cally with retinal locus. In measuring color gon Health Sciences University, Portland, Oregon. matches, we also obtained an index of red/green color Supported by National Institutes of Health grant EY-05047 and discrimination. by the Oregon Lions Sight and Hearing Foundation. In the following paper20 we show that most of these Submitted for publication: November 4, 1986. Reprint requests: Alvin Eisner, PhD, Neurological Sciences Insti- functional indices can be affected by RPE compro- tute, Good Samaritan Hospital and Medical Center, 1120 N. W. mise which has not yet caused acuity to decrease to 20th Avenue, Portland, OR 97209. worse than 20/20. 1824 Downloaded from iovs.arvojournals.org on 09/27/2021 No. 11 SENSITIVITIES IN HEALTHY OLDER EYES / Eisner er ol. 1825 Materials and Methods fundus photographs were taken of the macula. These photographs are evaluated in the following paper.20 Criteria For Subject Eligibility Written informed consent was obtained from all sub- Individuals of age 60 or older were eligible for in- jects. clusion into the study if they met the following set of criteria: Numbers of Subjects a) best corrected acuity of no worse than 20/30 in A total of 122 subjects with 20/20 or better best either eye (however data are reported only for eyes corrected acuity in at least one eye were tested; 53 having 20/20 or better best corrected acuity; see females and 27 males in their sixties, 29 females and 8 "Statistical Considerations" below). males in their seventies, and 2 females and 3 males in b) intraocular pressure < 22 mm Hg in each eye. their eighties. Sixteen of these individuals had 20/20 c) no history or evidence of glaucoma, macular or better acuity in one eye and 20/25 acuity in the lesions, uveitis, diabetes, or ocular surgery. other. Five of these individuals had 20/20 or better d) no abnormal macular changes other than mac- acuity in one eye and 20/30 in the other. Out of 86 ular drusen or pigmentary changes. females, 25 took unspecified doses of estrogen. Eigh- e) no myopia > 5 diopters. teen of these 25 were in their sixties, six were in their f) not taking digitalis or chloroquine derivatives.21 seventies, and one was in her eighties. g) no congenital color blindness or color anomaly. Visual Function Testing Subject Recruitment Instrumentation: Two apparatuses were used for testing. Subjects were recruited from the following sources: through a newspaper article in which volunteers aged All threshold measurements were obtained using a 60 or older having normal vision were requested, by two channel Maxwellian view testing device having word of mouth from those who had already been an exit pupil of 1.23 mm. For each subject, the stop tested, from a retirement home for active living, which defined the test field was translated along the through recruitment letters at doctors' offices, at a optical path to the position which corresponded to hospital health fair, from among individuals accom- the subject's "mideye" spherically equivalent correc- panying someone else to the Eye Clinic, through ad- tion. (We define the mideye value for a given index as vertisements in newsletters for senior citizens, and the average of that index's values over a subject's two from patients attending the Eye Clinic for routine eyes.) Subjects positioned themselves by placing their examination. The sources are listed in order of de- brow and cheekbone against an eyepiece so that an creasing frequency. Subjects were paid $ 10 for partic- adapting field or an annular fixation aid appeared ipating in the study. maximally bright. For about 80% of the subjects tested, a chin rest was available. Subjects responded with a buzzer when the test spot appeared to reach Subject Screening criterion. Upon arriving at the Eye Clinic, potential subjects Rayleigh matches (primaries of peak wavelengths had histories taken by one of two certified ophthal- 546 nm, 588 nm and 649 nm with half height band- mic technicians. These same technicians then mea- widths of about 10 nm) were made on a free viewing sured potential subjects' distance Snellen acuities in anomaloscope in deutan mode with the field at opti- each eye separately by using a standard projection cal infinity. The proportion of 546 nm (G) and 649 system. If subjects read at least half the letters on the nm (R) light was controlled by varying the linear po- 20/20 line correctly using their own glasses, then they sition of a stage that carried two interference filters were not refracted. If potential subjects had poorer and a neutral density filter. The stage could be trans- acuity on initial testing, then they were manifest re- lated in a plane adjacent to a fixed square aperture fracted to their best corrected acuity. The acuities through which passed collimated light. The linear reported in this paper are defined using the criteria of position of the stage depended upon the setting of a at least half the letters on a line correct. Following micrometer, thus allowing adjustment of R/G ratios acuity testing, potential subjects were examined by a reliably and precisely to within about ±0.0005 log screening ophthalmologist (usually WMM). The unit. The luminance of the 588 nm (Y) light was fundus was viewed using a direct ophthalmoscope controlled using a neutral density wedge. The R/G with the pupil undilated. After psychophysical test- mixture and Y matching lights were directed into ing, the pupil was dilated and stereoscopic color separate integrating spheres, thereby producing uni- Downloaded from iovs.arvojournals.org on 09/27/2021 1826 INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE / November 1987 Vol. 28 formly illuminated fields. A mirror at 45° to the two upon a 1000 td, 480 nm background. The 20 Hz integrating sphere exit ports and an adjacent field flicker sensitivities were obtained following the S stop holder together served to produce bipartite fields cone sensitivities. Since 440 nm and 490 nm excite L of up to 6.5° diameter. Subjects viewed the bipartite and M cones in nearly equal proportion,24 S cones fields through a 200 mm focal length achromat lens.
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