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)

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.

Clinical imaging of macular pigment optical density and spatial distribution.

Clinical research continues to provide an increasing number of studies that reveal an association between macular pigment optical density (MPOD) and both visual function and ocular health. As a result, there is a growing need for repeatable, accurate measures of MPOD that can describe peak optical density as well as spatial distribution. Measurement of MPOD in a research setting has an established history encompassing a number of both objective and subjective techniques. Transition of these techniques to a clinical setting has produced an array of commercial devices using three primary methods: heterochromatic flicker photometry, fundus autofluorescence and fundus reflectometry. The inherent differences among the techniques create difficulty in making direct comparisons between MPOD measurement devices. Understanding the limitations of each technique is critical in the clinical interpretation of MPOD results. Here, both the objective and subjective methods of MPOD measurement are reviewed with emphasis on the commercially available devices used in clinical settings.

Modified Photodynamic Therapy Treatment of Central Serous Chorioretinopathy.

PURPOSE: Central serous chorioretinopathy (CSC) is a condition characterized by serous detachment of the neurosensory retina at the level of the retinal pigmented epithelium (RPE) as a result of leakage from the choriocapillaris. The pathophysiology of CSC is not completely understood rendering treatment and management decisions more complex. When an observational approach and topical medical therapy are unsuccessful, a surgical intervention may be necessary. Here, we examine the role of modified photodynamic therapy (PDT) in recurrent CSC with multiple points of RPE leakage. CASE REPORT: A 37-year-old male patient presented a case of recurrent CSC in the left eye. After an initial presentation of a large area of submacular fluid, near complete resolution was seen in 8 weeks using a topical NSAID protocol and close monitoring. Two weeks later, a second serous neurosensory detachment larger than the first occurred. The recurrent CSC was successfully treated with focal grid laser photocoagulation and modified PDT resulting in complete resolution and return of visual function 4 months after the initial presentation. CONCLUSIONS: CSC is a multifactorial condition with the potential to severely impair daily visual function. Spectral domain optical coherence tomography retinal imaging has provided a remarkable tool in the diagnosis and monitoring of CSC. The addition of FA and ICG can create a highly precise picture of the subretinal fluid. Although most patients will spontaneously resolve, a subset of patients may benefit from medical therapy including topical nepafenac 0.1%. A smaller subset will require surgical intervention. Modified PDT with ICG-guided laser photocoagulation has a growing body of evidence as an effective treatment for recurrent CSC. Modified PDT may be the best course of action for chronic, non-resolving RPE leakage for both paramacular and foveal leaks leading to minimization of adverse visual effects.

Diagnosis and management of blepharitis: an optometrist's perspective.

Blepharitis is a condition characterized by inflammation of the eyelid margin and is a common cause of discomfort and irritation among people of all ages, ethnicity, and sex. In general, blepharitis is not a sight-threatening condition, but if left untreated has the potential to cause keratopathy, corneal neovascularization and ulceration, and permanent alterations in eyelid morphology. Historically, blepharitis has been categorized according to multiple structural classifications, including anatomic location, duration, and etiology. The substantial overlap of symptoms and signs from the differing structural classifications has led to initial misdiagnoses, clinical underreporting, and variability in treatment of blepharitis. The multifactorial nature is still not fully appreciated but infection and inflammation have been identified as the primary contributors. Ongoing clinical research continues the pursuit for a treatment panacea; however, long-term management of the underlying causes of blepharitis remains the best clinical approach. Here, we will attempt to review the existing literature as it pertains to clinical management of blepharitis and address a stepwise approach to diagnosis, treatment, and management.

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.

Macular pigment optical density spatial distribution measured in a subject with oculocutaneous albinism.

PURPOSE: Previous studies of macular pigment optical density (MPOD) distribution in individuals with oculocutaneous albinism (OCA) have primarily used objective measurement techniques including fundus reflectometry and autofluorescence. We report here on a subject with OCA and their corresponding MPOD distribution assessed through heterochromatic flicker photometry (HFP). METHODS: A subject with a history of OCA presented with an ocular history including strabismus surgery of the LE with persistent amblyopia and mild, latent nystagmus. Best corrected visual acuity was 20/25- RE and 20/40- LE. Spectral domain optical coherence tomography (SD-OCT) and fundus photography were also obtained. Evaluation of MPOD spatial distribution up to 8 degrees eccentricity from the fovea was performed using HFP. RESULTS: SD-OCT indicated a persistence of multiple inner retinal layers within the foveal region in the RE and LE including symmetric foveal thickening consistent with foveal hypoplasia. Fundus photography showed mild retinal pigmented epithelial (RPE) hypopigmentation and a poorly demarcated macula. OriginPro 9 was used to plot MPOD spatial distribution of the subject and a 33-subject sample. The OCA subject demonstrated a foveal MPOD of 0.10 with undetectable levels at 6 degrees eccentricity. The study sample showed a mean foveal MPOD of 0.34 and mean 6 degree eccentricity values of 0.03. CONCLUSIONS: Consistent with previous macular pigment (MP) studies of OCA, overall MPOD is reduced in our subject. Mild phenotypic expression of OCA with high functional visual acuity may represent a Henle fiber layer amenable to additional MP deposition. Further study of MP supplementation in OCA patients is warranted.

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).