Short-wavelength Sensitivity Research Articles

Short-Wavelength Sensitivity for Activating Effects of Light: An Ascent to the Arcane?

Short-Wavelength Sensitivity for Activating Effects of Light: An Ascent to the Arcane?

Cone visual pigments of aquatic mammals

It has long been hypothesized that the visual systems of animals are evolutionarily adapted to their visual environment. The entrance many millions of years ago of mammals into the sea gave these new aquatic mammals completely novel visual surroundings with respect to light availability and predominant wavelengths. This study examines the cone opsins of marine mammals, hypothesizing, based on previous studies [Fasick et al. (1998) and Levenson & Dizon (2003)], that the deep-dwelling marine mammals would not have color vision because the pressure to maintain color vision in the dark monochromatic ocean environment has been relaxed. Short-wavelength-sensitive (SWS) and long-wavelength-sensitive (LWS) cone opsin genes from two orders (Cetacea and Sirenia) and an additional suborder (Pinnipedia) of aquatic mammals were amplified from genomic DNA (for SWS) and cDNA (for LWS) by PCR, cloned, and sequenced. All animals studied from the order Cetacea have SWS pseudogenes, whereas a representative from the order Sirenia has an intact SWS gene, for which the corresponding mRNA was found in the retina. One of the pinnipeds studied (harp seal) has an SWS pseudogene, while another species (harbor seal) appeared to have an intact SWS gene. However, no SWS cone opsin mRNA was found in the harbor seal retina, suggesting a promoter or splice site mutation preventing transcription of the gene. The LWS opsins from the different species were expressed in mammalian cells and reconstituted with the 11-cis-retinal chromophore in order to determine maximal absorption wavelengths (lambda(max)) for each. The deeper dwelling Cetacean species had blue shifted lambda(max) values compared to shallower-dwelling aquatic species. Taken together, these findings support the hypothesis that in the monochromatic oceanic habitat, the pressure to maintain color vision has been relaxed and mutations are retained in the SWS genes, resulting in pseudogenes. Additionally, LWS opsins are retained in the retina and, in deeper-dwelling animals, are blue shifted in lambda(max).

Short-wavelength automated perimetry in patients with migraine

The aim was to investigate short-wavelength sensitivity deficits in patients with migraine. Fifteen migraine and 18 age-matched healthy volunteers with normal ophthalmologic examination participated in this study. Migraine characteristics were graded by the Migraine Disability Assessment Questionnaire (MIDAS). All participants underwent SWAP (short wavelength amplitude perimetry) testing using a Humphrey field analyzer; there was a 30-2 presentation pattern. Short wavelength amplitude perimetry parameters for mean deviation (MD; p<0.0001) and pattern standard deviation (PSD; p<0.0001) were significantly worse in the migraine group. In the migraine group 53.3%. of eyes had glaucoma hemi-field tests (GHT) outside normal limits and 10 of these had early glaucomatous visual field loss. Statistically significant correlations were found between frequency of migraine attacks and MD (p=0.02; r=0.56) and PSD (p=0.03; r=0.41) and also between the MIDAS score and MD (p=0.03; r=0.49) and PSD (p=0.04; r=0.51). In all migraine cases with early glaucomatous visual field defect a corresponding site of the head was predominantly involved in headache (p=0.03). Some patients with severe migraine have earlier defects on SWAP suggesting a common vascular insult of glaucoma and migraine, and all migraine cases with high MIDAS scores should be further evaluated for early glaucomatous visual field defects using SWAP.

Evaluation of S-cone Sensitivity in Reattached Macula Following Macula-Off Retinal Detachment Surgery

To investigate the recovery of short-wavelength sensitivity in patients who had undergone successful reattachment of a rhegmatogenous retinal detachment with macular involvement. Postoperative assessment of the visual acuity and the visual fields by standard achromatic automated perimetry (SAP), and short-wavelength automated perimetry (SWAP, Humphrey visual field analyzer; macula test pattern) was performed on 12 patients after the macula was reattached. The follow-up period was up to 12 months. The visual acuity and SAP sensitivity recovered rapidly after reattachment, with further moderate improvements up to 6 months after reattachment. The improvements stabilized by 9 to 12 months. The SWAP sensitivities improved more slowly than the visual acuity or SAP sensitivities, but they continued to improve even when visual acuity or SAP sensitivities had stabilized. We conclude that measurement of the sensitivities of the short-wavelength-sensitive cones (S-cones) with SWAP may be a sensitive method to evaluate the visual recovery of the reattached macula following macula-off retinal detachment.

Short-Wavelength Sensitivity of the Human Circadian System to Phase-Advancing Light

Short-Wavelength Sensitivity of the Human Circadian System to Phase-Advancing Light

Topical dorzolamide increases pericentral visual function in age‐related maculopathy: pilot study findings with short‐wavelength automated perimetry

Numerous studies have confirmed the enhancement of ocular circulation by carbonic anhydrase inhibitors (CAIs). Topical CAI treatment with dorzolamide averts the significant pericentral visual function loss accompanying retinal and choroidal vasoconstriction during acute hyperventilation-induced hypocapnia. This study was designed to discern whether dorzolamide might similarly enhance macular function in patients with age-related maculopathy (ARM). In a masked, placebo-controlled study, 40 patients with ARM and acuity > 20/50 were randomized to receive either dorzolamide or placebo for 12 weeks, thrice daily. After pre-study perimetric training, pericentral function (mean sensitivity) was quantified using Humphrey 10-2 short-wavelength automated perimetry (SWAP), before and after 12 weeks of topical therapy. Dorzolamide-treated eyes demonstrated a significant increase in mean sensitivity of + 1.55 dB (p = 0.04); placebo-treated eyes showed no significant change (+ 0.58 dB; p = 0.10). Given the non-significant increase of mean sensitivity in the placebo-treated group, fewer than 100 subjects per group would be required to afford > 70% power to yield a significant direct comparative difference between treatment and placebo in a prospective, randomized study of equally short duration. This study demonstrated a significant increase in short-wavelength sensitivity in ARM with dorzolamide and the lack thereof with placebo. These encouraging pilot study data suggest a potential role for topical CAIs in ARM patients, and establish objective parameters for prospective studies to further evaluate the effects of dorzolamide in ARM.

Changes in human short-wavelength-sensitive and achromatic resolution acuity with retinal eccentricity and meridian

Psychophysical measurements using achromatic grating resolution acuity in peripheral vision show a prominent retinal asymmetry in acuity which is consistent with predicted values based on available estimates of midget ganglion cell density. Recent studies have shown that peripheral grating resolution acuity values for short-wavelength-sensitive (SWS) isolating gratings in normal observers are closely related to predicted values based on the underlying small bistratified ganglion cell density. By measuring SWS resolution acuity at different locations across the visual field, we wished to see if any significant acuity asymmetry exists for the short-wavelength system. In addition to this, we wanted to compare SWS and achromatic resolution acuity at different retinal locations of equal eccentricity. SWS and achromatic grating resolution acuity was measured in two observers at a number of different retinal meridians of 10- and 25-deg eccentricity from the fovea, and out to 35-deg eccentricity along the horizontal meridian. Achromatic resolution acuity was higher than SWS resolution acuity at all locations. At 10-deg eccentricity there was slight radial asymmetry in SWS and achromatic acuity, both displaying highest acuity along the horizontal meridian. At 25-deg eccentricity, SWS and achromatic acuity showed significant asymmetry with acuity being higher in the nasal retina compared to the temporal retina and with higher acuity in the superior retina compared to the inferior retina. At 35-deg eccentricity, the acuity asymmetry along the horizontal meridian was maintained with acuity for both significantly higher in the nasal retina. The SWS acuity changes with eccentricity and meridian were qualitatively similar to that found for achromatic acuity at the majority of retinal locations. Like achromatic acuity, SWS acuity shows significant asymmetry at different retinal locations of equal eccentricity. This suggests that both the midget and small bistratified ganglion cell population density changes significantly with retinal location and eccentricity. SWS acuity appears to change in parallel with achromatic acuity for the majority of retinal locations measured, although the amount of nasotemporal asymmetry appears to be slightly less for the SWS system at 25- and 35-deg eccentricity.

Acoustostimulated expansion of the short-wavelength sensitivity range of AlGaAs/GaAs Solar cells

The effect of ultrasonic waves on the spectral sensitivity of solar energy converters based on AlGaAs/GaAs heterostructures has been studied. Ultrasonic treatment of a zinc-doped graded-gap AlxGa1−xAs film leads to the formation of a surface layer sensitive to electromagnetic radiation in the wavelength range λ < 0.551 μm. It is established that this layer is formed as a result of the acoustostimulated inward diffusion of zinc from the surface to the bulk of the graded-gap layer. The observed expansion of the short-wavelength sensitivity range and an increase in the efficiency of nonequilibrium charge carrier collection in AlGaAs/GaAs solar cells are due to improvement of the crystal defect structure and the dopant redistribution under the action of ultrasound.

How well does color perimetry isolate responses from individual cone mechanisms?

Over the past two decades there has been renewed interest in the use of color perimetry as a means of detecting early functional defects resulting from glaucomatous optic neuropathy and other forms of ophthalmic and neurologic pathology. The most popular form of color perimetry employs a colored background that selectively desensitizes two of the cone mechanisms, while the wavelength of the test target is selected to favor detection by the remaining, relatively unadapted, cone mechanism. While there are data to support the assertion that blue on yellow perimetry adequately isolates the short wavelength sensitive (SWS) cone mechanism, the only estimates of isolation of the other two cone mechanisms are for the region of the visual field corresponding to the fovea. The purpose of this experiment was thus to determine the amount of cone mechanism isolation that is afforded by automated perimetry when using yellow, blue, and magenta adapting backgrounds. To estimate cone mechanism isolation, we determined spectral sensitivity for a range of narrow-band stimuli using a standard 30-2 program on a modified Humphrey perimeter. Targets were presented against three different backgrounds of different luminance; yellow at 2.1 log cd.m-2, magenta at 1.3 log cd.m-2, and blue at 1 log cd.m-2. Sensitivity values for each background at each stimulus position were plotted as a function of wavelength, normalized, and then fitted with cone sensitivity templates to determine the relative sensitivity of the three cone mechanisms. The maximum relative isolation of an individual cone mechanism was achieved with a yellow background, where there was an average relative isolation of 0.94 for the SWS cone mechanism; the blue background provided a relative isolation of 0.89 for the long wavelength sensitive (LWS) cone mechanism. The magenta background proved poor at isolating the medium wavelength sensitive (MWS) cone mechanism, where a relative isolation of only 0.51 was obtained. Although color perimetry is capable of isolating individual cone mechanisms, the magnitude of isolation in normal observers may be small under certain circumstances. Therefore, when the technique is used to examine pathologic states, it may be necessary to employ at least two target wavelengths to determine the cone mechanism that is performing target detection. Furthermore, we suggest that MWS cone mechanism isolation may be improved through the combination of the so-called silent substitution technique with that of selective adaptation.

Peripheral resolution for achromatic and SWS gratings in early to moderate glaucoma and the implications for selective ganglion cell density loss.

To investigate whether there is significant selective reduction in short-wavelength-sensitive (SWS) ganglion cell density in early to moderate glaucoma. Peripheral achromatic resolution acuity (an indirect measure of the underlying midget ganglion cell density) and peripheral chromatic resolution acuity under conditions of blue cone isolation (an indirect measure of the underlying small bistratified ganglion cell density) were measured at 13 degrees eccentricity in four oblique meridians in 15 eyes (mean age, 64.6 +/- 9.6 years) with early to moderate glaucoma. The results from the subjects with glaucoma were compared with those in a group of 17 age-matched normal eyes (mean age, 62.5 +/- 6.6 years). Mean achromatic resolution acuity across the four locations was significantly lower in the subjects with glaucoma than in the normal subjects (2.92 vs. 4.01 cyc/deg). Mean chromatic resolution acuity across the four locations was also significantly lower in the subjects with glaucoma than the normal subjects (0.78 vs. 0.99 cyc/deg). There was no selective loss of mean SWS acuity in the subjects with glaucoma. Individual location analysis revealed that the chromatic-achromatic resolution ratio was not significantly different in the subjects with glaucoma who had early glaucomatous damage when compared with the normal subjects. The chromatic-achromatic resolution ratio was lower than normal at certain locations in certain individuals with early glaucoma. The results indicate that there is no evidence of significant selective reduction in global SWS ganglion cell density in early to moderate glaucoma. However, there may be selective loss of SWS ganglion cell density at individual locations in individual eyes.

Regeneration of ultraviolet-sensitive cones in the retinal cone mosaic of thyroxin-challenged post-juvenile rainbow trout (Oncorhynchus mykiss).

Previous studies in our laboratory have examined the loss of ultraviolet-sensitive (UVS) cones and UV sensitivity. This study looks at the question of regeneration of UVS cones and its topographic distribution, along with several other measures of the cone mosaic. Topography of the cone mosaic in rainbow trout smolts (post-metamorphic juveniles) was examined under normal growth conditions and during an exogenous thyroid hormone (TH) challenge. Growth of trout retina was studied over six weeks. Retinas sampled at 0, 3 and 6 weeks were embedded in EPON resin, and thick (1 micro m) tangential sections were stained with Richardson's stain. Sites representing central ventral, ventral, temporal, dorsal and nasal retina were sampled. Variables measured were cone densities, mean double cone diameter and mean spacing between cones of the same type. These same variables were compared with those of fish that were challenged with L-thyroxin (T4), and regeneration of UVS cones was assessed. Principal components of the correlation matrix of all photoreceptor measurements were analysed using analysis of variance. Here, we show several interesting effects of thyroxin exposure on post-metamorphic rainbow trout: (1) controls at week 0 have a high density of UVS cones in the temporal and dorsal sampling regions and a high density of blue (short-wavelength)-sensitive (SWS) and double cones across all regions sampled; (2) both control and TH-treated fish had less abundant, larger and less tightly packed SWS and double cones and a lower density of UVS cones in the temporal and dorsal sampling regions three and six weeks into the experiment compared with the starting condition at week 0; (3) fish treated with TH had a higher UVS cone density in the nasal and ventral sampling regions and there were higher densities of SWS and double cones in the central ventral, temporal and ventral regions, but lower densities in the nasal sampling regions, relative to the controls. The regeneration of UVS cones into the ventral retinal hemisphere in post-juvenile salmonids has important implications for visually guided behavior.

The cone visual pigments of an Australian marsupial, the tammar wallaby (Macropus eugenii): sequence, spectral tuning, and evolution.

Studies on marsupial color vision have been limited to very few species. There is evidence from behavioral, electroretinographic (ERG), and microspectrophotometric (MSP) measurements for the existence of both dichromatic and trichromatic color vision. No studies have yet investigated the molecular mechanisms of spectral tuning in the visual pigments of marsupials. Our study is the first to determine the mRNA sequence, infer the amino acid sequence, and determine, by in vitro expression, the spectra of the cone opsins of a marsupial, the tammar wallaby (Macropus eugenii). This yielded some information on mechanisms and evolution of spectral tuning of these pigments. The tammar wallaby retina contains only short-wavelength sensitive (SWS) and middle-wavelength sensitive (MWS) pigment mRNAs. This predicts dichromatic color vision, which is consistent with conclusions from previous behavioral studies ( Hemmi 1999). We found that the wallaby has a SWS1 class pigment of 346 amino acids. Sequence comparison with eutherian SWS pigments predicts that this SWS1 pigment absorbs maximally (lambdamax) at 424 nm and, therefore, is a blue rather than a UV pigment. This (lambdamax) is close to that of the in vitro-expressed wallaby SWS pigment (lambdamax of 420 +/- 2 nm) and to that determined behaviorally (420 nm). The difference from the mouse UV pigment (lambdamax of 359 nm) is largely accounted for by the F86Y substitution, in agreement with in vitro results comparing a variety of other SWS pigments. This suggests that spectral tuning employing F86Y substitution most likely arose independently in the marsupials and ungulates as a result of convergent evolution. An apparently different mechanism of spectral tuning of the SWS1 pigments, involving five amino acid positions, evolved in primates. The wallaby MWS pigment has 363 amino acids. Species comparisons at positions critical to spectral tuning predict a lambdamax near 530 nm, which is close to that of the in vitro-expressed pigment (529 +/- 1 nm), but quite different from the value of 539 nm determined by microspectrophotometry. Introns interrupt the coding sequences of the wallaby, mouse, and human MWS pigment sequences at the same corresponding nucleotide positions. However, the length of introns varies widely among these species.

Short-wavelength automated perimetry in patients with diabetes mellitus without macular edema.

The short-wavelength-sensitive (SWS) cone-mediated sensitivity is a sensitive indicator of functional changes of the macula in diabetic maculopathy. This study was performed to investigate whether functional losses of the macula are detectable in patients without a significant macular edema. In 45 patients with diabetes mellitus with clear optical media and no macular edema, conventional white-on-white perimetry (WWP) and short-wavelength automated perimetry (SWAP) were performed in the central 10-deg field. Fifty-eight healthy subjects ranging in age from 16 to 62 years served as controls. The two groups did not differ in age. Variance analysis (ANOVA) revealed significantly lower sensitivity in patients with diabetes than in controls. SWAP thresholds were significantly more greatly reduced by diabetes than those of WWP (ANOVA interaction: P=0.003). Post-hoc testing revealed a sensitivity reduction of 2.8 dB ( P=0.0003) in patients with diabetes for SWAP versus 0.46 for WWP ( P=0.15). Subgroup analysis revealed that mean thresholds of SWAP and WWP predominantly were reduced in patients with advanced disease. In patients with no retinopathy, sensitivity was not affected at all. SWS sensitivity may be affected in patients with diabetic retinopathy without clinically significant macular edema. Sensitivity loss was pronounced with increasing severity of retinopathy, reflecting the global status of the eye.

Topographies of retinal cone photoreceptors in two Australian marsupials.

Microspectrophotometry indicates the presence of at least three cone visual pigments in two Australian marsupials, the fat-tailed dunnart (Sminthopsis crassicaudata) and honey possum (Tarsipes rostratus). Here we have examined the distribution of cone types using antisera, JH455 and JH492, that recognize short-wavelength-sensitive (SWS) and medium-to-long-wavelength-sensitive (M/LWS) cone opsins, respectively. SWS cones were concentrated in dorso-temporal retina in the dunnart with a shallow decreasing gradient extending to the periphery (2300-1500/mm2). In the honey possum, SWS cones showed a uniform distribution (2700/mm2), except for a slight increase in a narrow peripheral band (3100/mm2). In both species, M/LWS cones dominated and their distributions were similar to those of retinal ganglion cells: a horizontal streak in the dunnart (31,000-21,000/mm2) and a shallow mid-ventral to peripheral gradient in the honey possum (37,000-26,000/mm2). A low number of cones remained unlabeled when the antisera were combined revealing further minority cone population(s). We discuss cone distributions in relation to visual capabilities and requirements of the species.

Phase advancing human circadian rhythms with short wavelength light

The photoreceptor(s) responsible for photoresetting of the human circadian system have not been identified. The aim of the present study was to assess the ability of short wavelength light to alter the timing of circadian rhythms. Eleven male subjects were studied in 15 4-day trials with a single 4 h light pulse administered on day 3, immediately after habitual wake time. The magnitude of the phase shifts in the melatonin acrophase and offset were similar after white (4300 μW/cm 2) and short wavelength (28 μW/cm 2) light exposure even though the white light pulse contained 185-fold more photons than the short wavelength light. This finding suggests short wavelength sensitivity of the photoreceptors mediating synchronization of human circadian rhythms.

Complex distribution of avian color vision systems revealed by sequencing the SWS1 opsin from total DNA.

To gain insights into the evolution and ecology of visually acute animals such as birds, biologists often need to understand how these animals perceive colors. This poses a problem, since the human eye is of a different design than that of most other animals. The standard solution is to examine the spectral sensitivity properties of animal retinas through microspectophotometry-a procedure that is rather complicated and therefore only has allowed examinations of a limited number of species to date. We have developed a faster and simpler molecular method, which can be used to estimate the color sensitivities of a bird by sequencing a part of the gene coding for the ultraviolet or violet absorbing opsin in the avian retina. With our method, there is no need to sacrifice the animal, and it thereby facilitates large screenings, including rare and endangered species beyond the reach of microspectrophotometry. Color vision in birds may be categorized into two classes: one with a short-wavelength sensitivity biased toward violet (VS) and the other biased toward ultraviolet (UVS). Using our method on 45 species from 35 families, we demonstrate that the distribution of avian color vision is more complex than has previously been shown. Our data support VS as the ancestral state in birds and show that UVS has evolved independently at least four times. We found species with the UVS type of color vision in the orders Psittaciformes and Passeriformes, in agreement with previous findings. However, species within the families Corvidae and Tyrannidae did not share this character with other passeriforms. We also found UVS type species within the Laridae and Struthionidae families. Raptors (Accipitridae and Falconidae) are of the violet type, giving them a vision system different from their passeriform prey. Intriguing effects on the evolution of color signals can be expected from interactions between predators and prey. Such interactions may explain the presence of UVS in Laridae and Passeriformes.

Genetic evidence for the ancestral loss of short-wavelength-sensitive cone pigments in mysticete and odontocete cetaceans.

All mammals ancestrally possessed two types of cone pigments, an arrangement that persists in nearly all contemporary species. However, the absence of one of these cone types, the short-wavelength-sensitive (SWS) cone, has recently been established in several delphinoid cetacean species, indicating that the loss of this pigment type may be widespread among cetaceans. To evaluate the functional condition of SWS cones in cetaceans, partial SWS cone-opsin gene sequences were obtained from nuclear DNA for 16 species representing 12 out of the 14 extant mysticete (baleen) and odontocete (toothed) families. For all these species one or more mutations were identified that indicate that their SWS cone-opsin genes are pseudogenes and thus do not code for functional visual pigment proteins. Parsimonious interpretation of the distribution of some of these mis-sense mutations indicates that the conversion of cetacean SWS coneopsin genes to pseudogenes probably occurred before the divergences of the mysticete and odontocete suborders. Thus, in the absence of dramatic homoplasy, all modern cetaceans lack functional SWS cone visual pigments and, by extension, the visual capacities that such pigments typically support.

Short-wavelength acuity: optical factors affecting detection and resolution of blue–yellow sinusoidal gratings in foveal and peripheral vision

Previous studies have indicated that peripheral achromatic grating resolution is limited by the sampling density of the neural array (sampling limited), and largely unaffected by large amounts of optical defocus and significant changes in luminance. Under certain conditions, peripheral short-wavelength sensitive (SWS) grating acuity is also sampling limited. We wished to determine how the sampling-limited nature of SWS-driven grating resolution was affected by changing optical defocus and stimulus luminance. Using SWS-cone isolation techniques, detection and resolution acuity were measured for sinusoidal gratings under varying levels of stimulus mean luminance and optical defocus in the fovea and at 20° eccentricity. From 1.4 down to 0.3 cd/m 2 peripheral detection acuity was superior to resolution acuity, accompanied by observations of aliasing: there was little change in resolution performance throughout this range. For defocus up to 3–4 dioptres, peripheral detection acuity was superior to resolution but fell steadily: resolution performance remained flat throughout the same range. Unlike achromatic acuity, foveal resolution performance displayed some robustness to defocus but to a lesser degree than the periphery. Peripheral SWS-driven resolution remains sampling limited for large changes in stimulus luminance and optical defocus, and should thus be useful as a clinical test of SWS-driven ganglion cell density.

Changes in short‐wavelength resolution acuity with age and defocus in the periphery: implications for relative ganglion cell loss

Purpose: Resolution acuity is known to be sampling limited for achromatic gratings in peripheral vision. In addition, peripheral achromatic resolution is unaffected by defocus up to 3 D. We have also shown resolution for Short Wavelength Sensitive (SWS) system isolating gratings to be sampling limited in both the fovea and periphery. This means that measurements of peripheral resolution with either stimulus can potentially be used to estimate the density of the corresponding underlying retinal ganglion cell population. We wished to examine the effect of optical defocus on detection and resolution acuity for this stimulus and also determine how peripheral resolution declined with age for both the achromatic and SWS system.Methods: We measured detection and resolution for SWS‐isolating gratings in the fovea and at 20° eccentricity for optical defocus between 0 and 4 D. In addition we measured resolution acuity for both achromatic and SWS‐isolating gratings at 13° in four retinal locations in 50 normal subjects ranging in age from 12 to 70 years. Measurements of lens density (age‐related yellowing) were also made in subjects over 60 years of age.Results: Detection acuity was initially higher than resolution accompanied by observations of aliasing. Detection acuity declined steadily with defocus but SWS resolution acuity showed no decline until 1 D in the fovea and 3 D at 20°. Resolution acuity was higher for achromatic gratings than SWS‐isolating gratings at all ages and neither displayed any decline in performance until around 55 years. After this both declined in a parallel fashion at a rate of 10% per decade. The individual ratio of SWS/achromatic resolution (0.25) showed no correlation with increasing lens density.Conclusions: As resolution for both short‐wavelength and achromatic gratings is robust to optical attenuation and declines in a parallel fashion after 55 years there appears to be no selective loss of SWS‐driven ganglion cell density relative to achromatic density with age.

The contrast sensitivity function for detection and resolution of blue-on-yellow gratings in foveal and peripheral vision.

Previous studies using polychromatic gratings have shown that the peripheral grating contrast sensitivity function is significantly different when the task is resolution rather than detection. Specifically, in the middle frequency range, while resolution acuity drops suddenly to zero, detection performance continues up to much higher frequencies, accompanied by observations of aliasing. We wanted to determine if the same holds true for blue-cone isolating gratings in either foveal or peripheral vision. Contrast sensitivity function (CSFs) were measured at the fovea and 20 degrees eccentricity in the temporal retina under conditions of short-wavelength-sensitive (SWS)-cone pathway isolation using a two-alternative forced choice paradigm. The detection and resolution CSF were identical at the low frequency end but at higher frequencies resolution sensitivity falls abruptly while contrast detection remained possible till higher frequencies [cut-off frequencies: fovea detection 6.0 cycles (degree)(-1), resolution 4.6 cycles (degree)(-1); periphery detection 1.6 cycles (degree)(-1), resolution 1.05 cycles (degree)(-1)]. Aliasing was observable when spatial frequency exceeded the resolution limit. Medium/high contrast blue-cone-mediated resolution acuity is sampling limited in both the fovea and periphery. Previous studies of blue-cone contrast sensitivity which employed a detection task do not reflect the true resolution limit.