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Understanding the causes and consequences of wildfires in forests of the western United States requires integrated information about fire, climate changes, and human activity on multiple temporal scales. We use sedimentary charcoal accumulation rates to construct long-term variations in fire during the past 3,000 y in the American West and compare this record to independent fire-history data from historical records and fire scars. There has been a slight decline in burning over the past 3,000 y, with the lowest levels attained during the 20th century and during the Little Ice Age (LIA, ca. 1400-1700 CE [Common Era]). Prominent peaks in forest fires occurred during the Medieval Climate Anomaly (ca. 950-1250 CE) and during the 1800s. Analysis of climate reconstructions beginning from 500 CE and population data show that temperature and drought predict changes in biomass burning up to the late 1800s CE. Since the late 1800s , human activities and the ecological effects of recent high fire activity caused a large, abrupt decline in burning similar to the LIA fire decline. Consequently, there is now a forest "fire deficit" in the western United States attributable to the combined effects of human activities, ecological, and climate changes. Large fires in the late 20th and 21st century fires have begun to address the fire deficit, but it is continuing to grow.

We report 63 species of Curculionoidea that are new to New Brunswick (three species of Anthribidae, four species of Brentidae, three species of Dryophthoridae, three species of Brachyceridae, 50 species of Curculionidae). Among these are 27 species (two Anthribidae, two Brenthidae, one Brachyceridae, 22 Curculionidae) that are also newly recorded for the Maritime provinces, and one species, Plesiobaris disjuncta Casey (Curculionidae) that is newly recorded for Canada from New Brunswick and Quebec. Bagous planatus LeConte is reinstated to the faunal list of New Brunswick. Two species of Curculionidae are newly recorded from Nova Scotia and the Maritime provinces, and two others are reported for the first time for Prince Edward Island.

The goal of this study was to determine how enteric viruses persist within shellfish tissues. Several lines of novel evidence show that phagocytic blood cells (hemocytes) of Eastern oysters (Crassostrea virginica) play an important role in the retention of virus particles. Our results demonstrated an association of virus contamination with hemocytes but not with hemolymph. Live oysters contaminated overnight with hepatitis A virus (HAV) and murine norovirus (MNV) had 56% and 80% of extractable virus associated with hemocytes, respectively. Transfer of HAV-contaminated hemocytes to naïve (virus-free) oysters resulted in naïve oyster meat testing HAV positive for up to 3 weeks. Acid tolerance of HAV, MNV, poliovirus (PV), and feline calicivirus (FCV) correlated with the ability of each virus to persist within oysters. Using reverse transcription-PCR (RT-PCR) to evaluate persistence of these viruses in oysters, we showed that HAV persisted the longest (>21 days) and was most acid resistant, MNV and PV were less tolerant of acidic pH, persisting for up to 12 days and 1 day, respectively, and FCV did not persist (<1 day) within oysters and was not acid tolerant. This suggests that the ability of a virus to tolerate the acidic conditions typical of phagolysosomal vesicles within hemocytes plays a role in determining virus persistence in shellfish. Evaluating oyster and hemocyte homogenates and live contaminated oysters as a prelude to developing improved viral RNA extraction methods, we found that viruses were extracted more expediently from hemocytes than from whole shellfish tissues and gave similar RT-PCR detection sensitivities.

Purpose: To investigate the effect of intraocular straylight (IOS) on threshold measurements made by four types of perimetry: standard automated perimetry (SAP), frequency-doubling technology (FDT) perimetry, flicker-defined form (FDF) perimetry, and the Moorfields Motion Displacement Test (MDT)., Methods: Six healthy young (21-29 years) psychophysically experienced observers were tested five times with each perimeter, each time with one of five different white opacity filters (WOFs), to induce various levels of IOS. Each WOF gave rise to an increase in IOS, measured with a straylight meter, of between 10% and 200% from baseline and ranging in effect from normal ageing to significant cataract. The change in sensitivity from baseline was normalized, allowing comparison of standardized (z) scores (change divided by the standard deviation of normative values) for each instrument., Results: Average SAP, FDT, and FDF thresholds were significantly affected (P < 0.001) by moderate to large increases in IOS (50%-200%), whereas MDT remained largely unaffected over the same range of straylight levels., Conclusions: The Moorfields MDT shows greater resilience to the effects of additional straylight compared with SAP, FDT, or FDF.

The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States (US) is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, 'dust-bowl-like' megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming. So far, it has been unclear whether or not such megadroughts occurred in the southwestern US, and, if so, with what regularity and intensity. Here we show that periods of aridity lasting centuries to millennia occurred in the southwestern US during mid-Pleistocene interglacials. Using molecular palaeotemperature proxies to reconstruct the mean annual temperature (MAT) in mid-Pleistocene lacustrine sediment from the Valles Caldera, New Mexico, we found that the driest conditions occurred during the warmest phases of interglacials, when the MAT was comparable to or higher than the modern MAT. A collapse of drought-tolerant C(4) plant communities during these warm, dry intervals indicates a significant reduction in summer precipitation, possibly in response to a poleward migration of the subtropical dry zone. Three MAT cycles ∼2 °C in amplitude occurred within Marine Isotope Stage (MIS) 11 and seem to correspond to the muted precessional cycles within this interglacial. In comparison with MIS 11, MIS 13 experienced higher precessional-cycle amplitudes, larger variations in MAT (4-6 °C) and a longer period of extended warmth, suggesting that local insolation variations were important to interglacial climatic variability in the southwestern US. Comparison of the early MIS 11 climate record with the Holocene record shows many similarities and implies that, in the absence of anthropogenic forcing, the region should be entering a cooler and wetter phase.

Purpose: Vanishing Optotype letters have a pseudo high-pass design so that the mean luminance of the target is the same as the background and the letters thus 'vanish' soon after the resolution threshold is reached. We wished to determine the variability of acuity measurements using these letters compared to conventional letters, and in particular how acuity is affected by the number of alternatives available to the subject., Methods: Acuity was measured using high contrast letters of both conventional and Vanishing Optotype design for three experienced normal subjects. Thresholds were determined for central vision in a forced choice paradigm for two alternatives (2AFC; AU and OQ), 4AFC (AQUO), 6AFC (QUANGO) and 26AFC (whole alphabet) using a QUEST procedure. Three measurements were made for each condition., Results: Threshold letter size was always larger for the Vanishing Optotypes than conventional letters, although the size of this difference (0.11-0.34 logMAR) depended on the number of alternatives and what they were. The effect of the number of AFC, and the individual letters employed, was smaller for the Vanishing Optotypes, implying that they are more equally legible than conventional optotypes. Variability was also lower for the Vanishing Optotype sets (0.01-0.03 logMAR) than the conventional letter sets (0.03-0.06)., Conclusions: The smaller effect of the number of letter alternatives, combined with more equal discriminability and lower threshold variability, implies that Vanishing Optotypes may be appropriate targets from which to design letter charts to measure small clinical changes in acuity., (© 2010 The College of Optometrists.)

The introduced plant Miconia calvescens (Melastomataceae) poses a grave threat to Hawaii's native ecosystems and biodiversity. One potential candidate for classical biological control is Cryptorhynchus melastomae (Coleoptera: Curculionidae: Cryptorhynchinae), a stem-boring weevil from Central and South America. This weevil feeds on M. calvescens in its native Costa Rica and has been successfully reared under greenhouse conditions. Comparison of its environmental conditions in Costa Rica with those in the Miconia infested areas of Hawaii indicates the latter is a suitable habitat for C. melastomae. C. melastomae has one or two generations per year. Adults feed on new stems, petioles, leaf buds, veins, and lamina, whereas larvae mine the stem until pupation. Adults appear to prefer saplings for oviposition and feeding. Under greenhouse conditions both adults and larvae can seriously damage and kill small M. calvescens. Preliminary host testing indicates that C. melastomae may be family specific on Melastomataceae. However, because Hawaii lacks native melastomes and has many other serious melastome weeds, a family specific insect may be suitable as a biocontrol agent in this case., (© 2010 Entomological Society of America)

Purpose: The area of complete spatial summation (Ricco's area) is the largest stimulus size for which area × intensity is constant at threshold. The authors sought to investigate whether Ricco's area changes in early glaucoma to account for the decreased visual signal/noise ratio that may accompany retinal ganglion cell loss., Methods: Spatial summation functions were measured, and Ricco's area was determined at four 10° retinal locations in 24 patients with early glaucoma (total deviation at test locations, mean, -1.3 dB; range, +2 dB to -8 dB) and 26 age-similar healthy subjects under achromatic and S-cone isolation conditions. Achromatic grating resolution acuity was measured at the same locations to estimate functional ganglion cell density., Results: Ricco's area was enlarged in patients compared with controls for both achromatic (enlarged by: superior field, 0.57 log units, P < 0.01; inferior field, 0.72 log units, P < 0.01) and chromatic (enlarged by: superior field, 0.26 log units, P < 0.01; inferior field, 0.25 log units, P = 0.065) stimuli, with negligible vertical summation curve shifts along the intensity axis. Resolution acuity was significantly reduced in glaucoma patients in both hemifields (P < 0.001). There was a weak, but significant, relationship between Ricco's area and resolution acuity., Conclusions: Enlargement of Ricco's area completely compensates for reduced perimetric sensitivity in early glaucoma to maintain constant threshold at Ricco's area, suggesting an increase in signal pooling in response to ganglion cell loss. The rightward displacement of the spatial summation curve indicates that perimetric stimuli should be capable of modulating in size as well as/instead of contrast, which may boost the glaucoma signal within measurement noise.

Purpose: Previously, an association between the area of complete spatial summation (Ricco's area) and age under scotopic conditions had been found. The authors sought to determine whether Ricco's area is similarly associated with age under photopic achromatic and selective S-cone conditions in peripheral vision and whether any association relates to a loss of ganglion cell density as determined by measurements of peripheral grating resolution acuity., Methods: Achromatic spatial summation functions were plotted for 68 healthy subjects (aged 20-77 years) in four oblique meridians on a gray background field of 10 cd/m(2). Similar functions were generated for the S-cone pathway (isolated using Stiles' two-color threshold method) for the same locations. Ricco's area was determined using two-phase regression analysis. Achromatic peripheral grating resolution acuity was measured at the same locations using high-contrast Gabor stimuli, as an estimate of localized functional ganglion cell density., Results: There was a notable decrease in overall contrast sensitivity with age for all stimulus sizes. However, there was no evidence of age-related change in Ricco's area for either achromatic (superior field, r(2) = 0.05; inferior field, r(2) = 0.0007; all P > 0.05) or chromatic (superior field, r(2) = 0.01; inferior field, r(2) = 0.006; all P > 0.05) stimuli, despite a significant decrease in peripheral grating resolution acuity with age (superior field, r(2) = 0.15; inferior field, r(2) = 0.17; both P < 0.05)., Conclusions: An age-related decline in functional ganglion cell density is not accompanied by a significant change in Ricco's area for achromatic or chromatic stimuli.

The spatial variation in central retinal function determined from mfERG was compared to co-localised measurements of cone density in two normal subjects. Individual cone cells in the parafoveal region of the retina were identified from 1 degrees x1 degrees images of the photoreceptor mosaic using a modified Heidelberg retina tomograph (HRT). The variation in cone density compared well with previous histology and retinal imaging studies and was strongly linearly correlated (r=0.98, p<0.001) with mfERG amplitude within the central retina. Retinal function determined from mfERG amplitude appears to directly reflect the density of the cone cells in this region., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Purpose: To compare directly the robustness of standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), frequency-doubling perimetry (FDP), and grating-resolution perimetry (GRP) stimuli to different degrees of intraocular stray light induced by commercially available opacity-containing filters., Methods: Five white opacity filters of increasing density were used to simulate the typical forward light scatter and stray light values associated with age-related lens opacification and significant cataract. The individually induced intraocular stray light value for each filter was quantified with a stray light meter and plotted against individual perimetric thresholds for the right eyes of three normally sighted trained observers for SAP, SWAP, FDP, and GRP., Results: All tests were significantly but differently affected by increasing stray light. Overall average declines over a 1 log unit change in the stray light values were as follows: SAP, 4.85 dB; SWAP, 9.03 dB; FDP, 4.29 dB; and GRP, 1.36 dB. Standardized (z) scores were calculated after normalization to the spread of the normative data values for each instrument. These indicated that the standardized changes from baseline over the range of the five filters per log stray light unit were as follows: SAP, 2.177; SWAP, 1.96; FDP, 1.277; and GRP, 1.04., Conclusions: The increased stray light values induced by cataract-simulating filters has a significant effect on all tests. However, GRP, which is known to be limited by retinal sampling rather than contrast, remains the most robust of the tests to the effects of intraocular stray light. The degree to which the normative "sensitivity" range for different types of perimetry might incorporate a component caused by individual differences in intraocular stray light is discussed and requires further research.

Aims: To investigate relationships between retinal morphology and retinal function in patients with retinitis pigmentosa (RP) using optical coherence tomography (OCT) and multifocal electroretinography (mfERG)., Methods: In all, 14 patients with RP who had visual acuities of 0.2 logMAR or better and Humphrey central fields of 10 degrees or larger participated in the study along with 16 normal control subjects. The amplitudes and timings of the mfERG responses were compared with spatially corresponding measures of retinal layer thickness from OCT within the macula region (central 12 degrees )., Results: Eyes with RP showed thinning of the photoreceptor retinal (PR) layer and thickening of mid-inner retinal (MIR) layers beyond the fovea. mfERG amplitude was reduced in all regions, whereas mfERG timing was only significantly delayed at a retinal eccentricity of 6-12 degrees and was otherwise preserved within the foveal and parafoveal retina (0-6 degrees). PR layer thickness was correlated with mfERG amplitude across the macula region. mfERG timing was correlated with the total change in retinal thickness (combined PR thinning and MIR thickening) at an eccentricity of 6-12 degrees., Conclusions: The relationship between mfERG timing and retinal thickness in RP is dependent on the retinal eccentricity. Preserved timing in the central retina (0-6 degrees ), despite significant disruption to retinal laminar structure, could be suggestive of inner retinal remodelling or functional redundancy. Cone system activity derived from mfERG amplitude appears to be related to the thickness of the photoreceptor layer in the macula region.

Weber contrast, DeltaL/L, is a widely used contrast metric for aperiodic stimuli. Zele, Cao & Pokorny [Zele, A. J., Cao, D., & Pokorny, J. (2007). Threshold units: A correct metric for reaction time? Vision Research, 47, 608-611] found that neither Weber contrast nor its transform to detection-threshold units equates human reaction times in response to luminance increments and decrements under selective rod stimulation. Here we show that their rod reaction times are equated when plotted against the spatial luminance ratio between the stimulus and its background (L(max)/L(min), the larger and smaller of background and stimulus luminances). Similarly, reaction times to parafoveal S-cone selective increments and decrements from our previous studies [Murzac, A. (2004). A comparative study of the temporal characteristics of processing of S-cone incremental and decremental signals. PhD thesis, New Bulgarian University, Sofia, Murzac, A., & Vassilev, A. (2004). Reaction time to S-cone increments and decrements. In: 7th European conference on visual perception, Budapest, August 22-26. Perception, 33, 180 (Abstract).], are better described by the spatial luminance ratio than by Weber contrast. We assume that the type of stimulus detection by temporal (successive) luminance discrimination, by spatial (simultaneous) luminance discrimination or by both [Sperling, G., & Sondhi, M. M. (1968). Model for visual luminance discrimination and flicker detection. Journal of the Optical Society of America, 58, 1133-1145.] determines the appropriateness of one or other contrast metric for reaction time.

It is widely accepted, based on data from the last few decades and on model simulations, that anthropogenic climate change will cause increased fire activity. However, less attention has been paid to the relationship between abrupt climate changes and heightened fire activity in the paleorecord. We use 35 charcoal and pollen records to assess how fire regimes in North America changed during the last glacial-interglacial transition (15 to 10 ka), a time of large and rapid climate changes. We also test the hypothesis that a comet impact initiated continental-scale wildfires at 12.9 ka; the data do not support this idea, nor are continent-wide fires indicated at any time during deglaciation. There are, however, clear links between large climate changes and fire activity. Biomass burning gradually increased from the glacial period to the beginning of the Younger Dryas. Although there are changes in biomass burning during the Younger Dryas, there is no systematic trend. There is a further increase in biomass burning after the Younger Dryas. Intervals of rapid climate change at 13.9, 13.2, and 11.7 ka are marked by large increases in fire activity. The timing of changes in fire is not coincident with changes in human population density or the timing of the extinction of the megafauna. Although these factors could have contributed to fire-regime changes at individual sites or at specific times, the charcoal data indicate an important role for climate, and particularly rapid climate change, in determining broad-scale levels of fire activity.

To determine the age-related change in the peripheral short-wavelength-sensitive (SWS) grating contrast sensitivity function (CSF), cut-off spatial frequency (acuity) and contrast sensitivity for both a detection and resolution task were measured at 8 degrees eccentricity under conditions of SWS-cone isolation for 51 subjects (19-72 years). The acuity for both the detection and resolution task declined with age, the detection acuity being significantly higher than the resolution acuity at all ages (p<.01). The CSF for both detection and resolution shifted towards lower spatial frequencies with increasing age. The contrast sensitivity for detection remained higher than that for resolution for all ages at the highest spatial frequencies. The age-related loss in the SWS resolution CSF at high spatial frequency probably reflects a loss occurring at the ganglion cells level.

We investigated relationships between retinal structure using optical coherence tomography (OCT) and retinal function using peripheral resolution acuity and multifocal electroretinograms (mfERG) in 56 subjects with a range of refractive errors (+0.50 to -15.00 D). Retinal thinning occurred in moderate and high myopia which appeared to be primarily due to reduced thickness of the middle to inner retina (MIR) (outer plexiform layer to the nerve fiber layer). MIR thickness was correlated with reduced spatial resolution and delayed mfERG timing in the peripheral retina. The findings suggest the structure and function of the post-receptor retina is susceptible to disruption in moderately and highly myopic eyes.

We measured resolution acuity separately for gratings with positive (+S) and negative (-S) S-cone contrast at different eccentricities in the temporal retina to determine if the resolution performance is limited by a single bipolar opponent mechanism. Gratings were modulated from an achromatic background in either the 90 or 270 deg direction in DKL space. Two additional directions were tested to examine the effects of increased lens yellowing and macular pigment absence in the periphery. The gratings used slow temporally rising hue (co-sinusoidal step) to aid selective S-cone ON or OFF stimulation. Resolution acuity was measured using different luminance ratios of the grating bars with the background around the equiluminant point. The data displayed a plateau where the acuity was minimal and mediated by the sparse S-cone pathway, with observer performance rising on either side. The acuity at the minimum was consistently higher for +S gratings than -S gratings beyond 10 deg eccentricity. Above the resolution limit, an aliased pattern was detected for both types of gratings, indicating that the resolution acuity was limited by the density of postreceptoral neurons. The results suggest that the resolution of gratings with opposite S-cone contrast polarity is limited by separate and rectified mechanisms of different distribution.

Ice loss to the sea currently accounts for virtually all of the sea-level rise that is not attributable to ocean warming, and about 60% of the ice loss is from glaciers and ice caps rather than from the two ice sheets. The contribution of these smaller glaciers has accelerated over the past decade, in part due to marked thinning and retreat of marine-terminating glaciers associated with a dynamic instability that is generally not considered in mass-balance and climate modeling. This acceleration of glacier melt may cause 0.1 to 0.25 meter of additional sea-level rise by 2100.

Hypertension is a medical condition commonly seen in the outpatient setting. Primary care providers should be aware that asymptomatic hypertension, despite the degree of elevation, is rarely an emergency. Based on consensus guidelines from the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure and the lack of any evidence showing harm, extreme blood pressure elevations do not need acute treatment. This article provides evidence for the argument that hypertension is rarely an emergency at all; even patients who have exceedingly high blood pressure can be treated as outpatients.

Purpose: To separately investigate the impact of simulated age-related lens yellowing, transparency loss and refractive error on measurements of macular pigment (MP) using resonance Raman spectroscopy., Methods: Two healthy young subjects with clear media underwent Raman spectroscopy under the following conditions: age-related lens yellowing was simulated using seven broad-band yellow filters with transmittance at 488 nm ranging from 0.54 to 0.90; cataract was simulated using five white filters of increasing opacity (scatter filters), the transmittance of which ranged from 0.42 to 0.86, each of which reduced peak contrast sensitivity by approximately 0.1 log units over the previous filter. Refractive error up to +6.25 D was achieved using soft contact lenses., Results: The Raman signal declined steadily to an average value of 43% of the starting value with the densest yellow filter in place. The white scatter filters produced a progressive linear reduction in signal resulting in almost complete signal loss with the densest filter. Refractive error resulted in an initial slight improvement in Raman count up to a value of +2.00 D followed by a decline thereafter., Conclusions: These results imply that lens yellowing and increasing scatter has an influence on the Raman signal and suggest that studies using this technology to estimate MP levels in older populations should carefully account for the status of the lens.

Aim: To investigate whether two methods of measuring macular pigment-namely, heterochromatic flicker photometry (HFP) and resonance Raman spectroscopy (RRS)--yield comparable data., Methods: Macular pigment was measured using HFP and RRS in the right eye of 107 participants aged 20-79 years. Correlations between methods were sought and regression models generated. RRS was recorded as Raman counts and HFP as macular pigment optical density (MPOD). The average of the top three of five Raman counts was compared with MPOD obtained at 0.5 degrees eccentricity, and an integrated measure (spatial profile; MPODsp) computed from four stimulus sizes on HFP., Results: The coefficient of variation was 12.0% for MPODsp and 13.5% for Raman counts. MPODsp exhibited significant correlations with Raman counts (r = 0.260, p = 0.012), whereas MPOD at 0.5 degrees did not correlate significantly (r = 0.163, p = 0.118). MPODsp was not significantly correlated with age (p = 0.062), whereas MPOD at 0.5 degrees was positively correlated (p = 0.011). Raman counts showed a significant decrease with age (p = 0.002) and were significantly lower when pupil size was smaller (p = 0.015)., Conclusions: Despite a statistically significant correlation, the correlations were weak, with those in excess of 90% of the variance between MPODsp and Raman counts remaining unexplained, meriting further research.

The carbon kinetic isotope effects (KIEs) of the reactions of several light non-methane hydrocarbons (NMHC) with Cl atoms were determined at room temperature and ambient pressure. All measured KIEs, defined as the ratio of the Cl reaction rate constants of the light isotopologue over that of the heavy isotopologue (Clk12/Clk13) are greater than unity or normal KIEs. For simplicity, measured KIEs are reported in per mil according to Clepsilon=(Clk12/Clk13 -1)x1000 per thousand unless noted otherwise. The following average KIEs were obtained (all in per thousand): 10.73+/-0.20 (ethane), 6.44+/-0.14 (propane), 6.18+/-0.18 (methylpropane), 3.94+/-0.01 (n-butane), 1.79+/-0.42 (methylbutane), 3.22+/-0.17 (n-pentane), 2.02+/-0.40 (n-hexane), 2.06+/-0.19 (n-heptane), 1.54+/-0.15 (n-octane), 3.04+/-0.09 (cyclopentane), 2.30+/-0.09 (cyclohexane), and 2.56+/-0.25 (methylcyclopentane). Measurements of the 12C/13C KIEs for the Cl atom reactions of the C2-C8 n-alkanes were also made at 348 K, and no significant temperature dependence was observed. To our knowledge, these 12C/13C KIE measurements for alkanes+Cl reactions are the first of their kind. Simultaneous to the KIE measurement, the rate constant for the reaction of each alkane with Cl atoms was measured using a relative rate method. Our measurements agree with published values within+/-20%. The measured rate constant for methylcyclopentane, for which no literature value is available, is (2.83+/-0.11)x10-10 cm3 molecule-1 s-1, 1sigma standard error. The Clepsilon values presented here for the C2-C8 alkanes are an order of magnitude smaller than reported methane Clepsilon values (Geophys. Res. Lett., 2000, 27, 1715), in contrast to reported OHepsilon values for methane (J. Geophys. Res. (Atmos.), 2001, 106, 23, 127) and C2-C8 alkanes (J. Phys. Chem. A, 2004, 108, 11537), which are all smaller than 10 per thousand. This has important implications for atmospheric modeling of saturated NMHC stable carbon isotope ratios. 13C-structure reactivity relationship values (13C-SRR) for alkane-Cl reactions have been determined and are similar to previously reported values for alkane-OH reactions.

Purpose: To examine the relationship between short-wavelength-sensitive (SWS) resolution acuity and epidemiologically defined stages of early age-related maculopathy (ARM)., Methods: Subjects consisted of 88 adults aged 51 to 87 years. Psychophysical testing was undertaken in only one eye of each subject (the study eye). All study eyes had a LogMAR acuity of 0.30 (20/40 Snellen) or better. SWS and achromatic grating resolution acuity were measured at 6 degrees eccentricity from the fovea. Stereoscopic color fundus photographs centered on the macula were taken on both eyes of each subject and were graded using the Wisconsin Age-Related Maculopathy Grading System (WARMGS). After grading, features of ARM were combined to assign a severity stage from 0 to 5 using the methods described by the Rotterdam Eye Study. Relationships between visual function, study eye ARM stage, and fellow eye status were examined with the use of standard statistical analysis., Results: Although SWS resolution acuity was significantly reduced in eyes classified as having any ARM compared with eyes classified as having no ARM (P = 0.002), there was no relationship between the severity of functional deficits and the morphologic severity from stage 1 to stage 4. On reassigning subject eyes to a revised severity staging (stage 0, stages 1 to 4 combined, and stage 5), SWS acuity was significantly different among these three groups (P < 0.001). No significant relationship was found between achromatic resolution acuity and ARM staging. The status of the fellow eye (advanced macular degeneration present or absent) was not significantly related to visual function in the study eye., Conclusions: Significant functional deficits in SWS resolution acuity were found in eyes with ARM features, but the severity of functional loss did not correlate well with the currently accepted method of assigning a morphologic severity stage. Longitudinal studies may reveal further information on the relationships between functional deficits, ARM status, disease progression, and outcome.

Short-wavelength-sensitive (SWS) resolution acuity has been reported to be limited by the density of the responding ganglion cells for people without appreciable age-related lenticular change. This study measured the robustness of SWS-cone acuity and contrast sensitivity (CS) to simulated lens yellowing and opacification. Resolution acuity at 8 deg eccentricity proved robust to significant amounts of yellowing and remained lower than detection acuity, indicating that the resolution continued to be limited by ganglion cell density. Both the detection and resolution CS functions were affected by simulated lens yellowing, except for resolution close to the CS cut-off. For simulated opacification, only dense opacity significantly affected performance. SWS resolution acuity and CS close to the resolution limit are resistant to moderate simulated age-related lens changes and continue to be mediated by the density of the responding ganglion cells, indicating important clinical potential to measure SWS neural losses of vision in older subjects.