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Dark-Adaptation Functions in Molecularly Confirmed Achromatopsia and the Implications for Assessment in Retinal Therapy Trials
摘要： PURPOSE. To describe the dark-adaptation (DA) functions in subjects with molecularly proven achromatopsia (ACHM) using refined testing conditions with a view to guiding assessment in forthcoming gene therapy trials. METHODS. The DA functions of nine subjects with ACHM were measured and compared with those of normal observers. The size and retinal location of the stimuli used to measure DA sensitivities were varied in four distinct testing condition sets, and the effect of altering these parameters assessed. RESULTS. In three of the four testing condition sets, achromats had significantly higher mean final thresholds than normal observers, whereas in the fourth condition set they did not. A larger, more central stimulus revealed the greatest difference between the final DA thresholds of achromat and normal subjects, and also demonstrated the slowest rate of recovery among the achromat group. CONCLUSIONS. In this, the largest study of DA functions in molecularly proven ACHM to date, we have identified optimal testing conditions that accentuate the relative difference between achromats and normal observers. These findings can help optimize DA testing in future trials, as well as help resolve the dichotomy in the literature regarding the normality or otherwise of DA functions in ACHM. Furthermore, the shorter testing time and less intense adaptation light used in these experiments may prove advantageous for more readily and reliably probing scotopic function in retinal disease, and be particularly valuable in the frequent post therapeutic assessments required in the context of the marked photophobia in ACHM.
关键词： rod monochromatism,dark adaptation,achromatopsia,rod vision,gene therapy
更新于2025-09-23 15:22:29
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Characterization of Rod Function Phenotypes Across a Range of Age-Related Macular Degeneration Severities and Subretinal Drusenoid Deposits
摘要： PURPOSE. To examine spatial changes in rod-mediated function in relationship to local structural changes across the central retina in eyes with a spectrum of age-related macular degeneration (AMD) disease severity. METHODS. Participants were categorized into five AMD severity groups based on fundus features. Scotopic thresholds were measured at 14 loci spanning 6° to 18° along the vertical meridian from one eye of each of 42 participants (mean = 71.7 ± 9.9 years). Following a 30% bleach, dark adaptation was measured at eight loci (4° to 12°). Rod intercept time (RIT) was defined from the time to detect a ?3.1 log cd/m2 stimulus. RITslope was defined from the linear fit of RIT with decreasing retinal eccentricity. The presence of subretinal drusenoid deposits (SDD), ellipsoid (EZ) band disruption, and drusen at the test loci was evaluated using optical coherence tomography. RESULTS. Scotopic thresholds indicated greater rod function loss in the macula, which correlated with increasing AMD group severity. RITslope, which captures the spatial change in the rate of dark adaptation, increased with AMD severity (P < 0.0001). Three rod function phenotypes emerged: RF1, normal rod function; RF2, normal scotopic thresholds but slowed dark adaptation; and RF3, elevated scotopic thresholds with slowed dark adaptation. Dark adaptation was slowed at all loci with SDD or EZ band disruption, and at 32% of loci with no local structural changes. CONCLUSIONS. Three rod function phenotypes were defined from combined measurement of scotopic threshold and dark adaptation. Spatial changes in dark adaptation across the macula were captured with RITslope, which may be a useful outcome measure for functional studies of AMD.
关键词： age-related macular degeneration,RIT,SDD,scotopic thresholds,dark adaptation,rod intercept time,subretinal drusenoid deposits,AMD
更新于2025-09-23 15:22:29
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Determining Optimal Test Parameters for Assessing Dark Adaptation in People With Intermediate Age-Related Macular Degeneration
摘要： PURPOSE. The primary aim was to determine optimal test conditions for evaluating dark adaptation in intermediate age-related macular degeneration (iAMD) in order to minimize test time while maintaining diagnostic sensitivity. METHODS. People with AMD and age-similar controls were recruited (aged >55 years). Rod intercept time (RIT) was assessed after a 76%, 70%, and 65% rhodopsin bleach at 5° eccentricity and 76% and 70% bleach at 12°. Test order was randomized and a 30-minute washout period added between tests. Results were compared between control and iAMD groups and receiver operating characteristics (ROC) curves were constructed. RESULTS. A total of 26 participants with variable grades of macular health attended for two visits. There was a statistically significant difference in average RIT between the control and iAMD groups at 5° (median, IQR controls = 5.8 minutes, 3.8–7.5; iAMD = 20.6 minutes, 11.1–30.0; Mann-Whitney, P = 0.01) and at 12° (mean, controls: 4.54 minutes ± 2.12 SD, iAMD = 7.72 minutes ± 3.37 SD; independent samples t-test, P = 0.03) following a 76% bleach. Area under the ROC curves was 0.83 (confidence interval [CI]: 0.64–1.0) and 0.79 (CI: 0.59–0.99) for these two test conditions, respectively. Five participants (45%) in the iAMD group had RITs >20 minutes for 76% bleach at 5°, but none for any other test condition. CONCLUSIONS. Nearly half of the participants with iAMD produced unacceptably long recovery times (>20 minutes) using a 76% bleach at 5° eccentricity. The 76% bleach at 12° provided almost equivalent separation between AMD and controls but recovery was achieved within 20 minutes.
关键词： rod intercept time,age-related macular degeneration,dark adaptation
更新于2025-09-23 15:22:29
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The importance of dark adaptation for forensic examinations; an evaluation of the Crime-lite Eye?
摘要： Forensic practitioners are recommended to dark adapt their eyes prior to conducting evidential searches in the dark. The dark adaptation process remains poorly standardised across the discipline, with little quanti?ed regarding the bene?ts of such preparative steps. Herein, we report the ?ndings of a study that recruited 50 participants to assess the e?ectiveness of the Crime-lite Eye?, a darkness adaptation device developed to assist forensic practitioners both in the laboratory and in ?eld. Participants were tasked with searching for the ?uorescent signatures left by reaction of 1,8-diaza?uoren-9-one (DFO) with amino acids, in a manner akin to the ?uorogenic ?ngerprint treatment of porous evidence. Using an Epson Stylus Photo R265 inkjet printer, ink cartridges were ?lled with alanine solutions of various concentrations, allowing di?erent motifs to be printed onto copy paper and subsequently developed using DFO. Participants searched for this ‘evidence’ both with and without dark adapted vision. On average, participants were able to locate and correctly recognise 16% more evidence once dark adapted using the Crime-lite Eye?. The increase in evidence located by participants once dark adapted suggests that crime scene o?cers should be dark adapting in order to visualise as much as possible. The time taken to dark adapt, 10 min on average during this study, is not excessively long, and should not signi?cantly slow the investigation.
关键词： Fingerprints,Fluorescence,Dark adaptation,Crime scene,Evidence,Crime-lite Eye
更新于2025-09-23 15:21:01
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The Impact of LED Color Rendering on the Dark Adaptation of Human Eyes at Tunnel Entrances
摘要： The dark adaptation of drivers’ eyes at a tunnel entrance seriously affects traffic safety. This can be improved by the design of tunnel lighting. Light-Emitting Diode (LEDs) have been applied as a new type of luminaire in tunnel lighting in recent years, but at present, there are few studies on the influence of color rendering of LEDs on tunnel traffic safety, and there is no explicit indicator for the selection of appropriate color rendering parameters in tunnel lighting specifications, which has aroused researchers’ concern. In this article, several new color rendering evaluation indexes were compared, and as a result, it is considered that CRI2012 (a color difference-based color rendering index) is more suitable for evaluating the color rendering of LEDs used at tunnel entrances. The dark adaptation phenomenon was simulated in the laboratory. Four CRI2012s, three color temperatures and eight colored targets were used in the experiments. The results showed that yellow, silver and white can provide shorter reaction times, while red and brown lead to longer reaction times, which can provide a reference for the design of road and warning signs at tunnel entrances. The effect of target color on reaction time was greater than that of color rendering. Under most target colors, the higher the CRI2012, the shorter the reaction time. When designing the color rendering of the LEDs at a tunnel entrance, the value should thus be as large as possible (close to 100), and a lower color temperature value (about 2800 K) should be selected. This paper provides technical support for tunnel lighting design and a reference for tunnel lighting specifications, which is of significance to improve driving safety and avoid traffic accidents in highway tunnels.
关键词： color rendering,dark adaptation,tunnel entrance,tunnel lighting,traffic safety
更新于2025-09-16 10:30:52
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Slowed Dark Adaptation in Early AMD: Dual Stimulus Reveals Scotopic and Photopic Abnormalities
摘要： The recovery of visual sensitivity after a photobleach in early AMD is slowed in rods but cones also may be abnormal. The purpose of this article was to test different stimulus locations to investigate cone function and its relation to rod abnormalities. Stimuli were presented at two locations, 3.08 and 5.58, in the inferior visual field. Post photobleach dark adaptation (DA) curves from 50 early-AMD patients were compared with those from 15 healthy controls of similar age. Curves were characterized in terms of four parameters: ct, cone threshold; a, the transition point from cone to rod function; S2, the slope of the second rod-mediated component; and b, the transition from the second to the third rod-mediated component. There were strong location effects for the healthy group and the AMD group. Cone threshold was higher for the outer compared with the inner stimulus (P ? 0.001), S2 was steeper for outer compared with inner (P < 0.001), a was shorter for outer (P ? 0.004), and b was shorter for outer than inner (P ? 0.002). The high variance in the patient data, particularly for a and b, explained the absence of a group*location interaction in the statistics. The data provide a novel perspective on abnormal cone- and rod-sensitivity recovery in early dry AMD. The comparison of pairs of DA curves from different locations highlights the involvement of cones in the underlying pathology of AMD. Dynamic measures of visual function are particularly sensitive to early AMD.
关键词： cones,dual location,rods,dark adaptation
更新于2025-09-11 14:15:04
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Light-Induced Thickening of Photoreceptor Outer Segment Layer Detected by Ultra-High Resolution OCT Imaging
摘要： PURPOSE. We examined if light induces changes in the retinal structure that can be observed using optical coherence tomography (OCT). METHODS. Normal C57BL/6J mice (age 3–6 months) adapted to either room light (15 minutes to ~5 hours, 50–500 lux) or darkness (overnight) were imaged using a Bioptigen UHR-OCT system. Confocal histologic images were obtained from mice killed under light- or dark-adapted conditions. RESULTS. The OCT image of eyes adapted to room light exhibited signi?cant increases (6.1 6 0.8 lm, n ? 13) in total retina thickness compared to the same eyes after overnight dark adaptation. These light-adapted retinal thickness changes occurred mainly in the outer retina, with the development of a hypore?ective band between the RPE and photoreceptor-tip layers. Histologic analysis revealed a light-evoked elongation between the outer limiting membrane and Bruch’s membrane from 45.8 6 1.7 lm in the dark (n ? 5) to 52.1 6 3.7 lm (n ? 5) in the light. Light-adapted retinas showed an increase of actin staining in RPE apical microvilli at the same location as the hypore?ective band observed in OCT images. Elongation of the outer retina could be detected even with brief light exposures, increasing 2.1 6 0.3 lm after 15 minutes (n ? 9), and 4.1 6 1.0 lm after 2 hours (n ? 6). Conversely, dark-adaptation caused outer retinal shortening of 1.4 6 0.4 lm (n ? 7) and 3.0 6 0.5 lm (n ? 8) after 15 minutes and 2 hours, respectively. CONCLUSIONS. Light-adaption induces an increase in the thickness of the outer retina and the appearance of a hypore?ective band in the OCT image. This is consistent with previous reports of light-induced ?uid accumulation in the subretinal space.
关键词： optical coherence tomography,subretinal space,retinal pigment epithelium,light/dark adaptation,outer segments
更新于2025-09-10 09:29:36
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Remote Ischemia Influences the Responsiveness of the Retina: Observations in the Rat
摘要： Remote ischemic preconditioning (RIP) has been found to be protective of heart and brain against ischemic injury. We have tested the effects of RIP on retinal function using the electroretinogram. METHODS. Ischemia remote from the retina was induced in one hindlimb, using a pressure cuff applied for between 5 and 10 minutes. A temperature probe on the footpad con?rmed blockage of the circulation. To test the impact of RIP on retinal function, we recorded the dark-adapted ?ash electroretinogram (ERG) in four groups (n ? 5 per group) of Sprague-Dawley rats (sham, 5-minute, 10-minute, and 2 3 5-minute ischemia). Heart rate, breath rate, and peripheral oxygen saturation were monitored using infrared pulse oximetry. RESULTS. RIP increased both the a- and b-waves by up to 14%, more markedly after the longer periods (10 minutes or 2 3 5 minutes) of ischemia. The effect was tested up to 30 minutes after ischemia and retested at 1 week and 1 month. RIP did not appear to accelerate the initial stages of recovery from photopigment bleach. Systemic oxygen saturation, heart rate, and respiration did not vary consistently during or after remote ischemia. CONCLUSIONS. The effect of RIP on the ERG is a novel ?nding. Possible mechanisms of this effect are discussed and related to the idea of neuroprotection and to fundamentals of the electroretinogram.
关键词： remote ischemic preconditioning,ATP-sensitive potassium channel,dark adaptation,adenosine,electroretinogram,retina
更新于2025-09-09 09:28:46
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The Effects of Diabetic Retinopathy and Pan-Retinal Photocoagulation on Photoreceptor Cell Function as Assessed by Dark Adaptometry
摘要： The pathophysiology of vision loss in persons with diabetic retinopathy (DR) is complex and incompletely defined. We hypothesized that retinal pigment epithelium (RPE) and rod and cone photoreceptor dysfunction, as measured by dark adaptometry, would increase with severity of DR, and that pan-retinal photocoagulation (PRP) would exacerbate this dysfunction. Dark adaptation (DA) was measured in subjects with diabetes mellitus and healthy controls. Dark adaptation was measured at 58 superior to the fovea following a flash bleach, and the data were analyzed to yield cone and rod sensitivity curves. Retinal layer thicknesses were quantified using spectral-domain optical coherence tomography (OCT). The sample consisted of 23 controls and 73 diabetic subjects. Subjects with moderate nonproliferative diabetic retinopathy (NPDR) exhibited significant impairment of rod recovery rate compared with control subjects (P ? 0.04). Cone sensitivity was impaired in subjects with proliferative diabetic retinopathy (PDR) (type 1 diabetes mellitus [T1DM]: P ? 0.0047; type 2 diabetes mellitus [T2DM]: P < 0.001). Subjects with untreated PDR compared with subjects treated with PRP exhibited similar rod recovery rates and cone sensitivities. Thinner RPE as assessed by OCT was associated with slower rod recovery and lower cone sensitivity, and thinner photoreceptor inner segment/outer segment layer was associated with lower cone sensitivity. The results suggest that RPE and photoreceptor cell dysfunction, as assessed by cone sensitivity level and rod- and RPE-mediated dark adaptation, progresses with worsening DR, and rod recovery dysfunction occurs earlier than cone dysfunction. Function was preserved following PRP. The findings suggest multiple defects in retinoid function and provide potential points to improve visual function in persons with PDR.
关键词： pan-retinal photocoagulation,dark adaptation,diabetic retinopathy
更新于2025-09-09 09:28:46
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Macular Pigment and Visual Performance in Low-Light Conditions
摘要： By reducing rod intrusion and improving efficiency of neural signaling throughout the visual system, macular pigment (MP) could improve many aspects of visual performance in low-light level conditions. Our study examined this possibility for a variety of visual performance parameters, including spatial resolution, dark adaptation kinetics, and color detection.
关键词： light/dark adaptation,macular pigment,lutein,visual acuity,visual performance
更新于2025-09-04 15:30:14