Optometry Compensation Study: Narrowing Down the Unexplained Gender Wage Gap in Optometry.

SIGNIFICANCE: Men earn at least 6.5% more than women in their first full-time jobs as optometrists. For current salaries, the gender wage gap is more than 13%. This study details the gender wage gap that remains after controlling for practice ownership, residency training, and employer-defined full-time work. PURPOSE: The purpose of this study was to measure the gender wage gap by region and practice type for full-time optometrists who did not complete a residency and do not own their practice. METHODS: Participants completed an online survey, providing data for their first and current optometry positions and demographic information. Respondents who reported full-time employment in the United States, not completing a residency, and not owning their practice were selected for further analysis by census region and practice type. In each category, the gender wage gap was calculated. RESULTS: In all regions and practice types, men were paid higher starting salaries than women. For current salaries, men were paid higher in almost all regions and practice types. The wage gap increased from starting salary to current salary, although not in all regions and practice types. CONCLUSIONS: When practice ownership, residency completion, and full-time work are controlled for, there remains a difference in the pay received by men and women in optometry. The salary data presented in this study may help optometrists narrow the wage gap.

Is the Helmholtz-Kohlrausch Effect More Robust in Women?

For gray or achromatic objects, brightness is a relatively simple transformation where very low luminance levels are perceived as black and higher levels are perceived as white. For chromatic objects, the transformation is more complex, depending on color purity as well. This influence of color purity on a color's perceived brightness is a well-established phenomenon known as the Helmholtz-Kohlrausch (H-K) effect. We investigated gender differences in the H-K effect by measuring brightness (via direct brightness matching [DBM]) and luminance (via heterochromatic flicker photometry [HFP]) at five wavelengths (450, 520, 560, 580, and 650 nm) perceived as blue, green, green-yellow, yellow, and red hues. We compared DBM/HFP ratios between 13 males and 18 females. Based on previous evidence of a female advantage in chromatic processes, we hypothesized that DBM/HFP ratios would be higher in female subjects. While HFP measures were essentially the same between male and female subjects, DBM measures and DBM/HFP ratios were significantly higher for female subjects than males. There were no significant effects of contraceptive use based on a post hoc comparison. We also derived simple models of brightness as a function of luminance and saturation, which further suggest gender dimorphism in the H-K effect.

The Dominant Eye: Dominant for Parvo- But Not for Magno-Biased Stimuli?

Eye dominance is often defined as a preference for the visual input of one eye to the other. Implicit in this definition is the dominant eye has better visual function. Several studies have investigated the effect of visual direction or defocus on ocular dominance, but there is less evidence connecting ocular dominance and monocular visual thresholds. We used the classic "hole in card" method to determine the dominant eye for 28 adult observers (11 males and 17 females). We then compared contrast thresholds between the dominant and non-dominant eyes using grating stimuli biased to be processed more strongly either by the magnocellular (MC) or parvocellular (PC) pathway. Using non-parametric mean rank tests, the dominant eye was more sensitive overall than the non-dominant eye to both stimuli (z = -2.54, p = 0.01). The dominant eye was also more sensitive to the PC-biased stimulus (z = -2.22, p = 0.03) but not the MC-biased stimulus (z = -1.16, p = 0.25). We discuss the clinical relevance of these results as well as the implications for parallel visual pathways.

Influence of macular pigment optical density spatial distribution on intraocular scatter / Influencia de la distribución espacial de la densidad óptica del pigmento macular sobre la dispersión intraocular

Purpose: This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). Methods: A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16º using a 1º stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1º, 3.3º, 10º and 16º diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. Results: Spatial mapping identified mean values for discrete MPOD [0.32 (s.d. = 0.08)], MPOD summed across central 1º [0.37 (s.d. = 0.11)], MPOD summed across central 3.3º [0.85 (s.d. = 0.20)], MPOD summed across central 10º [1.60 (s.d. = 0.35)] and MPOD summed across central 16º [1.78 (s.d. = 0.39)]. Mean intraocular scatter was 0.83 (s.d. = 0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1º were near significance. Conclusions: While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device (AU)

Objetivo: Este estudio evaluó la suma de las mediciones de la distribución espacial de la densidad óptica del pigmento macular (MPOD) y sus efectos sobre la dispersión intraocular, utilizando un dispositivo comercialmente disponible (C-Quant, Oculus, EEUU). Métodos: Se utilizó un fotómetro intermitente heterocromático personalizado (cHFP) para medir la distribución espacial de la MPOD a lo largo de los 16º centrales, utilizando un estímulo de 1º. La MPOD se calculó como medición discreta y como las sumas de las mediciones a lo largo de los diámetros centrales de 1º, 3,3º, 10º y 16º. Se calculó la dispersión intraocular como media de los cinco ensayos en los que se lograron mediciones de fiabilidad y repetibilidad utilizando el dispositivo C-Quant. Se construyeron mapas de distribución espacial de la MPOD, examinándose los efectos sobre la dispersión intraocular, tanto de los valores discretos como de la suma de valores. Resultados: El mapeado espacial identificó valores medios para la MPOD discreta [0,32 (DE = 0,08)], la suma de MPOD a lo largo de 1º central [0,37 (DE = 0,11)], la suma de MPOD a lo largo de 3,3◦ centrales [0,85 (DE = 0.20)], la suma de MPOD a lo largo de 10º centrales [1,60 (DE = 0,35)] y la suma de MPOD a lo largo de 16◦ centrales [1,78 (DE = 0,39)]. La dispersión intraocular media fue de 0,83 (DE = 0,16) unidades log. A pesar de producirse una tendencia consistente hacia una relación inversa entre MPOD y dispersión, dichas relaciones no fueron estadísticamente significativas. Las correlaciones entre los cuartiles superior e inferior de la MPOD dentro de 1º central fueron próximas a la significación estadística. Conclusiones: A pesar de producirse una tendencia general hacia la disminución de la dispersión intraocular con el incremento de la MPOD, consistente con una atenuación selectiva de la luz visible con longitud de onda corta, ni los valores discretos ni la suma de valores de la MPOD reflejaron una influencia significativa sobre la dispersión intraocular, según las mediciones realizadas con el dispositivo C-Quant (AU)

Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue.

Purpose: The purpose of this study was to determine whether subjects who wear short wavelength-blocking eyeglasses during computer tasks exhibit less visual fatigue and report fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses. Methods: A total of 36 healthy subjects (20 male; 16 female) was randomized to wearing no-block, low-blocking, or high-blocking eyeglasses while performing a 2-hour computer task. A masked grader measured critical flicker fusion frequency (CFF) as a metric of eye fatigue and evaluated symptoms of eye strain with a 15-item questionnaire before and after computer use. Results: We found that the change in CFF after the computer task was significantly more positive (i.e., less eye fatigue) in the high-block versus the no-block (P = 0.027) and low-block (P = 0.008) groups. Moreover, random assignment to the high-block group but not to the low-block group predicted a more positive change in CFF (i.e., less eye fatigue) following the computer task (adjusted ß = 2.310; P = 0.002). Additionally, subjects wearing high-blocking eyeglasses reported significantly less feeling pain around/inside the eye (P = 0.0063), less feeling that the eyes were heavy (P = 0.0189), and less feeling that the eyes were itchy (P = 0.0043) following the computer task, when compared to subjects not wearing high-blocking lenses. Conclusions: Our results support the hypothesis that short-wavelength light-blocking eyeglasses may reduce eye strain associated with computer use based on a physiologic correlate of eye fatigue and on subjects' reporting of symptoms typically associated with eye strain.

Influence of macular pigment optical density spatial distribution on intraocular scatter.

PURPOSE: This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). METHODS: A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16° using a 1° stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1°, 3.3°, 10° and 16° diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. RESULTS: Spatial mapping identified mean values for discrete MPOD [0.32 (s.d.=0.08)], MPOD summed across central 1° [0.37 (s.d.=0.11)], MPOD summed across central 3.3° [0.85 (s.d.=0.20)], MPOD summed across central 10° [1.60 (s.d.=0.35)] and MPOD summed across central 16° [1.78 (s.d.=0.39)]. Mean intraocular scatter was 0.83 (s.d.=0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1° were near significance. CONCLUSIONS: While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device.

Macular pigment spatial distribution effects on glare disability / Efectos de la distribución espacial del pigmento macular en el nivel de discapacidad por deslumbramiento

Purpose: This project explored the relationship of the macular pigment optical density (MPOD) spatial profile with measures of glare disability (GD) across the macula. Methods: A novel device was used to measure MPOD across the central 16° of retina along four radii using customized heterochromatic flicker photometry (cHFP)at eccentricities of 0°, 2°, 4°, 6° and 8°. MPOD was measured as discrete and integrated values at all measured retinal loci. GD was calculated as a difference in contrast sensitivity (CS) between no glare and glare conditions using identical stimuli presented at the same eccentricities. GD was defined as [(CSNo Glare−CSGlare)/CSNo Glare] in order to isolate the glare attenuation effects of MPOD by controlling for CS variability among the subject sample. Correlations of the discrete and integrated MPOD with GD were compared. Results: The cHFP identified reliable MPOD spatial distribution maps demonstrating a 1st-order exponential decay as a function of increasing eccentricity. There was a significant negative correlation between both measures of foveal MPOD and GD using 6cycles per degree (cpd) and 9cpd stimuli. Significant correlations were found between corresponding parafoveal MPOD measures and GD at 2 and 4° of eccentricity using 9cpd stimuli with greater MPOD associated with less glare disability. Conclusions: These results are consistent with the glare attenuation effects of MP at higher spatial frequencies and support the hypothesis that discrete and integrated measures of MPOD have similar correlations with glare attenuation effects across the macula. Additionally, peak foveal MPOD appears to influence GD across the macula (AU)

Objetivo: Este estudio analizó el perfil espacial de la relación entre la densidad óptica del pigmento macular (MPOD) y las mediciones de deslumbramiento (glare) discapacitante (GD) a lo largo de la mácula. Métodos: Se utilizó un nuevo dispositivo para medir la MPOD a lo largo de los 16 grados centrales de la retina, distribuidos en 4 radios, utilizando un fotómetro intermitente heterocromático personalizado (cHFP) a excentricidades de 0, 2, 4, 6 y 8 grados. Se midió la MPOD como valores discretos e integrados, en todas las localizaciones retinianas medidas. Se calculó el GD como diferencia de sensibilidad al contraste (CS) entre las condiciones sin y con deslumbramiento, utilizando estímulos iguales, presentados en las mismas excentricidades. El GD se definió como [(CSNo Glare - CSGlare)/CSNo Glare] a fin de aislar los efectos de la MPOD en la atenuación del deslumbramiento mediante el control de la variabilidad de CS en la muestra de sujetos. Se compararon las mediciones de la MPOD discreta e integrada con GD. Resultados: El cHFP identificó unos mapas de distribución espacial fiables de la MPOD, que demostraron un deterioro exponencial de 1er orden, como función del incremento de la excentricidad. Se produjo una importante correlación negativa entre las mediciones de la MPOD foveal y el GD, utilizando estímulos de 6 ciclos por grado (cpd) y 9cpd. Se hallaron correlaciones significativas entre las mediciones correspondientes de la MPOD parafoveal y el GD a 2 y 4 grados de excentricidad, utilizando estímulos de 9cpd, siendo menor la discapacidad por deslumbramiento a mayor MPOD. Conclusiones: Estos resultados son consistentes con los efectos de del pigmento macular en la atenuación del deslumbramiento discapacitante para frecuencias espaciales altas, apoyando la hipótesis relativa a que las mediciones discretas e integradas de la MPOD tienen correlaciones similares con los efectos de atenuación del deslumbramiento a través de la mácula. Además, el pico foveal de MOPD parece influir en el GD macular (AU)

Comparison of retinal image evaluation techniques in novice clinicians.

Retinal fundus evaluation is learned through experience and training. This study aimed to determine the image presentation characteristics and the accompanying evaluation techniques, which led to the most accurate and efficient retinal pathology detection method. Phase I included 25 novice clinicians asked to evaluate 14 different pathologies using spatial versus temporal image presentations. Phase II included 25 different novice clinicians asked to evaluate five different simulated pathologies at three different pixel sizes presented in both spatial and temporal image presentations. Accuracy and speed of recognition were evaluated between the spatial and temporal presentations of the same simulated pathology. In phase l, subjects were significantly faster at simulated pathology detection using a temporal presentation with a 95% accuracy rate versus a spatial presentation with a 79% accuracy rate. In phase II, subjects demonstrated significant differences in speed of detection using the temporal technique at all 3 pixel number sizes with the greatest difference in detection times shown at the smallest retinal defects. Accuracy and speed of recognition in simulated pathology assessment were improved in a temporal presentation and the greatest improvements were demonstrated at the smallest pixel numbers.

Macular pigment spatial distribution effects on glare disability.

PURPOSE: This project explored the relationship of the macular pigment optical density (MPOD) spatial profile with measures of glare disability (GD) across the macula. METHODS: A novel device was used to measure MPOD across the central 16° of retina along four radii using customized heterochromatic flicker photometry (cHFP)at eccentricities of 0°, 2°, 4°, 6° and 8°. MPOD was measured as discrete and integrated values at all measured retinal loci. GD was calculated as a difference in contrast sensitivity (CS) between no glare and glare conditions using identical stimuli presented at the same eccentricities. GD was defined as [(CSNo Glare-CSGlare)/CSNo Glare] in order to isolate the glare attenuation effects of MPOD by controlling for CS variability among the subject sample. Correlations of the discrete and integrated MPOD with GD were compared. RESULTS: The cHFP identified reliable MPOD spatial distribution maps demonstrating a 1st-order exponential decay as a function of increasing eccentricity. There was a significant negative correlation between both measures of foveal MPOD and GD using 6 cycles per degree (cpd) and 9 cpd stimuli. Significant correlations were found between corresponding parafoveal MPOD measures and GD at 2 and 4° of eccentricity using 9 cpd stimuli with greater MPOD associated with less glare disability. CONCLUSIONS: These results are consistent with the glare attenuation effects of MP at higher spatial frequencies and support the hypothesis that discrete and integrated measures of MPOD have similar correlations with glare attenuation effects across the macula. Additionally, peak foveal MPOD appears to influence GD across the macula.

A comparison of the short-term settling of three scleral lens designs.

PURPOSE: Scleral gas-permeable lenses are rapidly gaining international popularity. Unlike corneal gas-permeable lenses, scleral lenses are fitted to the bulbar conjunctiva and settle into the tissue after insertion. To date, we are unaware of any studies examining the settling behavior of three varying scleral lens designs. The purpose of this study was to quantify the mean total settling and mean rates of settling for three scleral lens designs: Onefit P&A (Blanchard Contact Lens, Inc), Mini Scleral Design (msd) (Blanchard Contact Lens, Inc), and Jupiter (Visionary Optics). METHODS: A randomized, repeated-measures study of Onefit P&A, msd, and Jupiter was performed. Subjects were fitted from a trial lens set, according to the manufacturer's guidelines. After insertion, lens settling was measured at 0 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours. Statistical analyses were performed using analysis of variance and two-stage, nonlinear regression analyses of settling over time. RESULTS: On average, the Onefit P&A, msd, and Jupiter lenses settled a total of 113.7, 133.7, and 88.1 µm, respectively. Although the rates of settling were not linear, analysis of variance revealed a significant difference in the average settling rates (p < 0.05) among the groups. Tukey analyses revealed a significant difference in the settling rates for msd and Jupiter comparison (p < 0.05). Nonlinear regression analyses predicted that the lenses settled to about 80% of the final estimated values for the Onefit P&A lens, 90% for msd, and 99% for the Jupiter, after 8 hours. CONCLUSION: We concluded that the amount of settling varied significantly among the three lens designs. Settling rates were greatest shortly after insertion. Larger lenses were estimated to be settled by 8 hours. Based on the results of this short-term study, careful consideration to the settling patterns of individual scleral lens designs should be given.

Central serous chorioretinopathy produces macular pigment profile changes.

PURPOSE: Macular pigment (MP) is the collective name for three isomeric carotenoids: lutein, zeaxanthin, and meso-zeaxanthin. Macular pigment density is greatest in the central retina, peaking at the fovea and falling to negligible levels at 7 degrees of eccentricity from the fovea. Several studies have documented the interocular symmetry of MP optical density (MPOD) spatial distribution. The ongoing University of Missouri-St. Louis study uses a novel, customized heterochromatic flicker photometer to map the spatial distribution of MPOD up to 8 degrees of eccentricity relative to the fovea. Here, we report the MPOD measurements in a subject with resolved central serous chorioretinopathy (CSC) in the right eye. CASE REPORT: Two subjects performed the full MPOD spatial mapping. The test subject (WK) had a history of central serous CSC of the right eye. The control subject (CP) had an unremarkable ocular health history. Comprehensive exams were performed on each subject including Cirrus optical coherence tomography imaging and fundus photographs. Subject CP showed highly symmetric interocular MPOD profiles at the fovea and 2, 4, and 6 degrees of eccentricity. Subject WK showed interocular asymmetry at the fovea and at 2 degrees with relative symmetry at 4 and 6 degrees. A paired sample t test identified nonsignificant interocular values for subject CP and statistically significant differences of at 2 degrees for subject WK. CONCLUSIONS: We hypothesize that subject WK's interocular MPOD spatial distribution asymmetry resulted from his history of resolved CSC. This asymmetry is statistically significant at 2 degrees of retinal eccentricity and corresponds to the extent of retinal pigment epithelium changes observed on the fundus photographs. These findings suggest that MP and retinal pigment epithelium changes after a CSC episode are comparable in the area of the retina affected. These disruptions may also be measureable in other macular conditions in which the sensory retina is affected (e.g., cystoid macular edema and clinically significant macular edema).

Near-vision acuity levels and performance on neuropsychological assessments used in occupational therapy.

We investigated how induced blur affects performance on the Trail Making Test and Digit Symbol Test routinely used in occupational therapy cognitive evaluations. The study used a factorial design with both age (young and old adults) and simulated blur levels of near visual acuity (20/50 and 20/100) manipulated between participants. A sample of 124 healthy, community-living adults was used in the final analysis. Significant differences (p<.05) were found in performance for young participants between 20/50 and 20/100 blur level as well as between 20/20 and 20/100 blur level for the Digit Symbol Test. Scores for old participants decreased as a function of blur but were not significant. This study illustrates that cognitive evaluations used throughout the lifespan may require the appropriate visual acuity level to maximize performance. Occupational therapists' understanding of client factors and their effect on performance is fundamental to the client evaluation process.

Driver contrast sensitivity and reaction times as measured through a salt-covered windshield.

BACKGROUND: The objective of this study was to use contrast sensitivity measurements to determine the effect of windshield salt film on driver vision. This effect simulates road salt spray that dries in place on a vehicle windshield during winter driving conditions. METHODS: Ten emmetropic subjects were tested to assess contrast sensitivity functions through windshields that were clear compared with the same stimuli as viewed through windshields coated with salt film. Achromatic stimuli were generated by a VisionWorks system and were presented at 4 spatial frequencies (0.5, 3, 10, and 20 cycles per degree). RESULTS: A significant reduction in contrast sensitivity through the salt film was found at all spatial frequencies. In addition, reaction time to detect the stimuli was also found to be increased significantly at 2 of the 4 spatial frequencies through the saline-covered windshield. CONCLUSION: The results of this study indicate that windshield salt film reduces the ability to detect high and low contrast objects in a simulated driving environment as well as increases the subjects' reaction times.

Evaluation of the new web-based "Colour Assessment and Diagnosis" test.

PURPOSE: The purpose of the study was to determine the sensitivity, specificity, and repeatability of the web-based Colour Assessment and Diagnosis (CAD) test in comparison to current tests of color vision. METHODS: Thirty color normals and 30 color deficients, identified and diagnosed by the Nagel anomaloscope, were tested. The results of the CAD test were compared with standard tests like Nagel anomaloscope, Ishihara (concise version, 2001), Hardy, Rand and Rittler (HRR; 4 ed) pseudoisochromatic test, and the Farnsworth Munsell 100 (FM-100) hue test. RESULTS: Using the Nagel anomaloscope as the "gold standard," the sensitivity with the CAD test was 93.33%, Ishihara 96%, HRR 100%, and the FM-100 hue 100%. The specificity was 100% with CAD and the Ishihara color plates, whereas it was 33% with the HRR and 83% with the FM-100 hue test. The concurrent validity of the CAD test for color normals was 93.75%. The concurrent validity of CAD test for color deficiency was 100%. Thus, anyone failing the CAD test has a color defect. The coefficient of agreement for the Nagel anomaloscope and the CAD test was 0.93, with Ishihara it was 0.96, with the HRR it was 0.33, and with FM-100 hue it was 0.83. CONCLUSION: These results showed that the CAD test is a valid test for identifying congenital red-green color deficiency. Further testing is required in a larger population of anomalous trichromats.

Limits of learning enhancements with nicotine in old male rats.

Findings with young adult humans and animal models suggest that nicotine may serve both neuroprotective and cognition enhancing roles in old animals. A pair of experiments was conducted to examine drug-induced modification of the cholinergic nicotinic receptor subtype on rates of learning by young and aged rats. In experiment I males (4-7 months or 20-25 months old) were administered nicotine (0.0, 0.3 or 0.7 mg/kg injected s.c. daily) and tested in both a T-maze non-spatial discrimination paradigm and a hole board spatial task. Nicotine failed to improve acquisition by young animals on either task. Nicotine also failed to improve non-spatial learning by old animals. However, both dosages of nicotine improved performance by the old males in the spatial paradigm. In experiment II, a 5-choice serial discrimination paradigm designed to better evaluate visual attention and spatial working memory in aging was used. Groups of old male rats were administered nicotine or mecamylamine (2 or 8 mg/kg), an antagonist of the nicotinic cholinergic receptor. Results were that the 0.3 mg nicotine group learned the task fastest and achieved the highest learning asymptote. Both learning rates and final levels of performance were worst in the 8 mg mecamylamine group. However, the 2 mg mecamylamine rats were the equals of the control group and both reached a higher asymptote than the 0.7 mg nicotine group. These data suggest that healthy old animals can accrue benefits from nicotinic activation but that the benefits are complex, being limited to certain dosages and to specific cognitive skills.

Luminous efficiency and the measurement of daytime displays, signals, and visors.

PURPOSE: Measurements concerning the usability or safety of optical equipment are based on assumptions regarding luminous efficiency. The current luminous efficiency functions are derived from human sensitivity experiments taken at low light levels compared with the outdoor daytime environment. The amount of error induced by extrapolating from low light level data to high light level applications is not known. We sought to determine whether standard luminous efficiency curves CIE V(lambda) and CIE Heterochromatic Brightness Matching are appropriate for measuring day-use optical equipment such as display phosphors, lasers, LEDs, and laser eye protection, which are becoming more common in aviation. METHODS: Flicker photometry and successive heterochromatic brightness matching were used to measure changes in luminance efficiency functions with increasing levels (1, 10, 100, and 1000 fL) of light adaptation. RESULTS: Luminous efficiency was found to depend on both the method and the reference intensity with which the measurements were taken. For heterochromatic brightness matching, luminous efficiency increased for longer wavelengths as reference intensity increased. Peak luminous efficiency shifted from approximately 540 nm to greater than 600 nm with increasing intensity. Peak luminous efficiency was constant for flicker photometry across all intensities, but the function narrowed slightly at 100 fL. CONCLUSION: Luminous efficiency curves measured at high reference intensities are substantially different from the standard luminous efficiency functions. Caution should be used when measuring spectrally narrow and bright sources such as lasers and LEDs with a V(lambda) corrected photometer because the measured luminance may correlate poorly with perceived brightness.