Effect of chromatic filters on visual performance in individuals with mild traumatic brain injury (mTBI): A pilot study / Efecto de los filtros cromáticos en la función visual de sujetos con lesión cerebral traumática leve (mTBI): Estudio Piloto

Purpose: Spectral filters have been used clinically in patients with mild traumatic brain injury (mTBI). However, they have not been formally assessed using objective techniques in this population. Thus, the aim of the present pilot study was to determine the effect of spectral filters on reading performance and visuo-cortical responsivity in adults with mTBI. Methods: 12 adults with mTBI/concussion were tested. All reported photosensitivity and reading problems. They were compared to 12 visually-normal, asymptomatic adults. There were several test conditions: three luminance-matched control filters (gray neutral density, blue, and red), the patient-selected ‘precision tint lens’ that provided the most comfort and clarity of text using the Intuitive Colorimeter System, and baseline without any filters. The Visagraph was used to assess reading eye movements and reading speed objectively with each filter. In addition, both the amplitude and latency of the visual-evoked potential (VEP) were assessed with the same filters. Results: There were few significant group differences in either the reading-related parameters or VEP latency for any of the test filter conditions. Subjective improvements were noted in most with mTBI (11/12). Conclusions: The majority of patients with mTBI chose a tinted filter that resulted in increased visual comfort. While significant findings based on the objective testing were found for some conditions, the subjective results suggest that precision tints should be considered as an adjunctive treatment in patients with mTBI and photosensitivity (AU)

Objetivo: Los filtros espectrales han sido utilizados clínicamente en pacientes con lesión cerebral traumática leve (mTBI). Sin embargo, no han sido evaluados formalmente utilizando técnicas objetivas en esta población. Por tanto, el objetivo del presente estudio piloto fue el de determinar el efecto de dichos filtros sobre el rendimiento lector y la respuesta visual-cortical en adultos con mTBI. Métodos: Se realizaron pruebas a doce adultos con mTBI/conmoción. Todos ellos reportaron fotosensibilidad y problemas lectores. Se realizó una comparación con adultos asintomáticos y con visión normal. Las pruebas se llevaron a cabo bajo diversas situaciones: uso de tres filtros de control con equivalencia de luminosidad (gris con densidad neutra, azul, y rojo), ‘lentes tintadas de precisión’, seleccionadas por el paciente, que aportaban mayor confort y claridad de texto utilizando un sistema colorimétrico intuitivo, y valores basales sin utilizar ningún filtro. Se utilizó el Visagraph para evaluar los movimientos oculares durante la lectura y la velocidad lectora de manera objetiva con cada filtro. Además, se evaluaron tanto la amplitud como la latencia de los potenciales evocados visuales (VEP) con los mismos filtros. Resultados: Se produjeron pocas diferencias grupales significativas, tanto en relación a los parámetros relacionados con la lectura como a la latencia de los VEP, en cualquiera de las situaciones de prueba de los filtros. Se notaron mejoras subjetivas en la mayoría de sujetos con mTBI (11/12). Conclusiones: La mayoría de los pacientes con mTBI eligieron un filtro coloreado que incrementó su confort visual. Aunque se detectaron hallazgos significativos basados en las pruebas objetivas para algunas situaciones, los resultados subjetivos sugieren que deben considerarse las lentes tintadas de precisión como tratamiento adyuvante en los pacientes con mTBI y fotosensibilidad (AU)

Effect of chromatic filters on visual performance in individuals with mild traumatic brain injury (mTBI): A pilot study.

PURPOSE: Spectral filters have been used clinically in patients with mild traumatic brain injury (mTBI). However, they have not been formally assessed using objective techniques in this population. Thus, the aim of the present pilot study was to determine the effect of spectral filters on reading performance and visuo-cortical responsivity in adults with mTBI. METHODS: 12 adults with mTBI/concussion were tested. All reported photosensitivity and reading problems. They were compared to 12 visually-normal, asymptomatic adults. There were several test conditions: three luminance-matched control filters (gray neutral density, blue, and red), the patient-selected 'precision tint lens' that provided the most comfort and clarity of text using the Intuitive Colorimeter System, and baseline without any filters. The Visagraph was used to assess reading eye movements and reading speed objectively with each filter. In addition, both the amplitude and latency of the visual-evoked potential (VEP) were assessed with the same filters. RESULTS: There were few significant group differences in either the reading-related parameters or VEP latency for any of the test filter conditions. Subjective improvements were noted in most with mTBI (11/12). CONCLUSIONS: The majority of patients with mTBI chose a tinted filter that resulted in increased visual comfort. While significant findings based on the objective testing were found for some conditions, the subjective results suggest that precision tints should be considered as an adjunctive treatment in patients with mTBI and photosensitivity.

The effect of spectral filters on VEP and alpha-wave responses / Efecto de los filtros espectrales sobre el PVE y las respuestas de las ondas alfa

Purpose: Spectral filters are used to treat light sensitivity in individuals with traumatic brain injury (TBI); however, the effect of these filters on normal visual function has not been elucidated. Thus, the current study aimed to determine the effect of spectral filters on objectively-measured visual-evoked potential (VEP) and alpha-wave responses in the visually-normal population. Methods: The full-field (15°H×17°V), pattern-reversal VEP (20′ check size, mean luminance 52cd/m2) was administered to 20 visually-normal individuals. They were tested with four Intuitive-Colorimeter-derived, broad-band, spectral filters (i.e., gray/neutral density, blue, yellow, and red), which produced similar luminance values for the test stimulus. The VEP N75 and P100 latencies, and VEP amplitude, were recorded. Power spectrum analysis was used to derive the respective powers at each frequency, and peak frequency, for the selected 9-11Hz components of the alpha band. Results: Both N75 and P100 latencies increased with the addition of each filter when compared to baseline. Additionally, each filter numerically reduced intra-session amplitude variability relative to baseline. There were no significant effects on either the mean VEP amplitude or alpha wave parameters. Conclusions: The Intuitive Colorimeter filters significantly increased both N75 and P100 latencies, an effect which is primarily attributable (∼75%) to luminance, and in some cases, specific spectral effects (e.g., blue and red). VEP amplitude and alpha power were not significantly affected. These findings provide an important reference to which either amplitude or power changes in light-sensitive, younger clinical groups can be compared (AU)

Objetivo: Los filtros espectrales se utilizan para tratar la sensibilidad a la luz en individuos con lesión cerebral traumática (TBI); sin embargo, no se ha esclarecido el efecto de estos filtros sobre la función visual normal. Por ello, el estudio actual trató de determinar el efecto de los filtros espectrales sobre el potencial evocado visual (PVE) y las respuestas de las ondas alfa, medido objetivamente en la población con visión normal. Métodos: Se aplicó un PVE de campo completo (15°H×17°V), y patrón invertido (tamaño de estímulo de 20’, y luminancia media de 52cd/m2) a veinte individuos con visión normal. Se realizó la prueba utilizando cuatro filtros espectrales de banda ancha, derivados del Colorímetro Intuitivo (densidad gris/neutra, azul, amarillo y rojo), que produjeron unos valores de luminancia similares para los estímulos de la prueba. Se registraron las latencias N75 y P100, y la amplitud del PVE. Se utilizó el análisis del espectro de potencia para calcular las respectivas potencias en cada frecuencia, así como la frecuencia máxima, para los componentes seleccionados de 9-11Hz de la banda alfa. Resultados: Ambas latencias N75 y P100 se incrementaron con la incorporación de cada filtro, en comparación a la línea basal. Además, cada filtro redujo numéricamente la variabilidad de la amplitud intra-sesión, en relación a la línea basal. No se produjeron efectos significativos sobre la amplitud del PVE medio o los parámetros de la onda alfa. Conclusiones: Los filtros del Colorímetro Intuitivo redujeron considerablemente las latencias N75 y P100, un efecto que es principalmente atribuible a la luminancia (∼75%), y en algunos casos a los efectos espectrales específicos (es decir, el azul y el rojo). La amplitud del PVE y la potencia alfa no se vieron significativamente afectados. Estos hallazgos aportan una importante referencia para poder comparar tanto los cambios de amplitud como de potencia en los grupos clínicos de personas más jóvenes, con sensibilidad a la luz (AU)

The effect of spectral filters on VEP and alpha-wave responses.

PURPOSE: Spectral filters are used to treat light sensitivity in individuals with traumatic brain injury (TBI); however, the effect of these filters on normal visual function has not been elucidated. Thus, the current study aimed to determine the effect of spectral filters on objectively-measured visual-evoked potential (VEP) and alpha-wave responses in the visually-normal population. METHODS: The full-field (15°H×17°V), pattern-reversal VEP (20' check size, mean luminance 52cd/m(2)) was administered to 20 visually-normal individuals. They were tested with four Intuitive-Colorimeter-derived, broad-band, spectral filters (i.e., gray/neutral density, blue, yellow, and red), which produced similar luminance values for the test stimulus. The VEP N75 and P100 latencies, and VEP amplitude, were recorded. Power spectrum analysis was used to derive the respective powers at each frequency, and peak frequency, for the selected 9-11Hz components of the alpha band. RESULTS: Both N75 and P100 latencies increased with the addition of each filter when compared to baseline. Additionally, each filter numerically reduced intra-session amplitude variability relative to baseline. There were no significant effects on either the mean VEP amplitude or alpha wave parameters. CONCLUSIONS: The Intuitive Colorimeter filters significantly increased both N75 and P100 latencies, an effect which is primarily attributable (∼75%) to luminance, and in some cases, specific spectral effects (e.g., blue and red). VEP amplitude and alpha power were not significantly affected. These findings provide an important reference to which either amplitude or power changes in light-sensitive, younger clinical groups can be compared.

Effect of luminance on the visually-evoked potential in visually-normal individuals and in mTBI/concussion.

PURPOSE: To assess quantitatively the effect of luminance on VEP amplitude and latency in visually-normals (VN) and patients with mild traumatic brain injury (mTBI). METHODS: VN individuals (n = 20) and those with mTBI (n = 19) participated. Those with mTBI were assessed 1-10 years post-injury (mean = 4.97 years), with the exception of one subject. Pattern VEP testing was employed using the DIOPSYS™ NOVA-TR system, with a 74 cd m-2 baseline luminance. Luminance levels were reduced with five different neutral density (ND) filters (0.5, 1.0, 1.5, 2.0 and 2.5) and compared to the baseline response. All testing was performed under binocular-viewing conditions with full refractive correction in place. RESULTS: In both groups, mean VEP amplitude reduced with decrease in luminance (p < 0.05). At each luminance level, the mean VEP amplitude was significantly lower in mTBI than in the VN population (p < 0.05). In both groups, the mean VEP latency increased progressively with reduction in luminance (p < 0.05), with it being significantly higher in mTBI than in the VN population (p < 0.05). CONCLUSIONS: High luminance levels produced an optimal VEP response in both populations. VEP amplitude was robust, whereas latency progressively increased in both groups as luminance decreased. The latency increase with decreased luminance was significantly larger in those with mTBI, thus suggesting that latency can be used to differentiate reliably between VN individuals and those with mTBI.