Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

Lighting studies that take into account the age of the inhabitants of an area and are related to circadian light are difficult to find. This study aims to simplify a method to approximately compute the circadian light reaching the retina based on photopic illuminance reaching the corneal plane and considering the optical density of an aging crystalline lens. As an example of this proposed method, calculations were performed with both the D65 and A standard illuminants, showing how the spectral power distribution is modified by the optical density of the crystalline lens, mainly at short wavelengths. Due to these selective wavelength absorptions of the aged lens, a significant variation in the level of daylight equivalent melanopic illuminance (EDI) is present in the retina. With levels of 200 lux at the corneal plane, these variations ranged from 204 EDI lux to 178 EDI lux for the D65 standard illuminant, and from 99 EDI lux to 101 EDI lux for the A standard illuminant for observers aged 10 and 90, respectively. In this work, we aimed to simplify the greatest possible level of calculation of melanopic light, while describing simple protocols that are easy to translate into practice. Our results will allow researchers to carry out optimized lighting designs from both the photometric and circadian perspectives considering the optical density of an aging lens

Lighting-Induced Changes in Central and Peripheral Retinal Thickness and Shape after Short-Term Reading Tasks in Electronic Devices

Background: To assess retinal and optical changes associated with near vision reading for different lighting conditions in electronic screens. Methods: Twenty-four young healthy subjects participated in the study; an iPad and an Ebook were chosen as stimuli for 5 min of reading task with different lighting conditions. Central and peripheral retinal thicknesses in the macular ETDRS areas by optical coherence tomography were analyzed. Results: Significant differences were found between basal retinal thickness and retinal thickness after reading with iPad and high illumination, in the N6 (p = 0.021) and I6 (p = 0.049) areas, and low illumination (S3: p = 0.008, N3: p = 0.018, I3: p = 0.021, N6: p = 0.018 and I6: p = 0.020), being thinner after reading. The same trend was observed after reading with an Ebook and high lighting in the N3 (p = 0.037) and N6 (p = 0.028). For low lighting conditions, only retinal thinning was observed. After reading, retinal shape analysis revealed significant changes from computed basal eccentricity for high lighting conditions only. At the periphery, those differences in eccentricity values were statistically significant for both lighting conditions. Conclusions: Young people can recover visual quality after 5 min of reading tasks at different lighting levels on electronic devices, while peripheral retinal expansion remains altered, especially at low lighting levels

Cambios en la vascularización retiniana valorados mediante OCTA en pacientes diabéticos tipo 2 con retinopatía diabética

Significancia: El presente estudio es de interés ya que estudia los cambios microvasculares retinianos en pacientes diabéticos mediante angiografía por tomografía de coherencia óptica (OCTA). Una técnica nove- dosa y prometedora que permite detectar signos microvasculares tempranos en la diabetes mellitus (DM), incluso antes de que sean clínicamente evidentes. Propósito: Estudiar la vascularización retiniana en los plexos capilar superficial (PCS) y capilar profundo (PCP), así como la coriocapilar (CC) y el área de la zona avascular foveal (ZAF) mediante OCTA de barrido (DRI-Triton SS-OCT®, Topcon Corporation, Japan) en pacientes con diabetes mellitus tipo 2 (DM2), con reti- nopatía diabética (RD) moderada y sin edema macular diabético (EMD). Material y Métodos: La muestra estaba compuesta por un total de 88 ojos, de los cuales 54 pertenecientes al grupo DM2 con edades comprendidas entre 42 y 86 años, y 34 ojos pertenecientes al grupo control con edades de 47 a 83 años. Presentaban ametropías esféricas máximas de ±9,00 y ±3,00 D de astigmatismo, sin ninguna otra patología ocular. A todos los sujetos se les tomaron medidas con el autorrefractómetro, biometría ocular, agudeza visual (AV), presión intraocular (PIO) y OCTA en los plexos PCS, PCP y CC en los sectores central, superior, temporal, nasal e inferior, y también se midió el área de la ZAF en ambos plexos retinianos. Además de estas medidas se estudiaron las alteraciones anatómicas del grupo DM2 y se reco- gieron una serie de variables clínicas también en el grupo DM2, con datos tales como el tiempo de evolu- ción de la enfermedad y parámetros sobre el control metabólico de la DM. Se usaron test no paramétricos, concretamente el test de U de Mann-Whitney para muestras independientes para determinar la presencia o no de diferencias estadísticamente significativas (p<0,05) entre grupos. Resultados: Respecto al estudio de la densidad vascular mediante OCTA, el grupo de DM2 sí presentó resul- tados estadísticamente inferiores en el PCS frente al grupo control en las regiones Central, Superior y Nasal, y sin diferencias significativas en el PCP y en la CC. En el área de las ZAF se encontraron diferencias signifi- cativas, siendo la ZAF mayor en el grupo DM2 en el PCS (p<0,001), mientras que no se encontró diferencia en el PCP entre ambos grupos. En cuanto a la presencia de alteraciones anatómicas en los plexos retinianos, las más destacadas fueron la presencia de disrupción periférica en el PCS (83.30%), la presencia de microan- eurismas en el PCP (81.10%) y los cambios de flujo en el PCP (81.10%). Conclusiones: Los resultados del presente estudio muestran diferencias en la densidad vascular entre los dos grupos estudiados, siendo menor en el grupo DM2, y alcanzando diferencias estadísticamente sig- nificativas a nivel del PCS retiniano. Además, se encontró que la ZAF está aumentada en el grupo DM2 en ambos plexos retinianos, especialmente en el PCS. Los pacientes DM2 con RD moderada presentan alter- aciones anatómicas en el PCS, PCP y C

A reliable criterion for the correct delimitation of the foveal avascular zone in diabetic patients

Background: Manual segmentation of the Foveal Avascular Zone (FAZ) has a high level of variability. Research into retinas needs coherent segmentation sets with low variability. Methods: Retinal optical coherence tomography angiography (OCTA) images from type-1 diabetes mellitus (DM1), type-2 diabetes mellitus (DM2) and healthy patients were included. Superficial (SCP) and deep (DCP) capillary plexus FAZs were manually segmented by different observers. After comparing the results, a new criterion was established to reduce variability in the segmentations. The FAZ area and acircularity were also studied. Results: The new segmentation criterion produces smaller areas (closer to the real FAZ) with lower variability than the different criteria of the explorers in both plexuses for the three groups. This was particularly noticeable for the DM2 group with damaged retinas. The acircularity values were also slightly reduced with the final criterion in all groups. The FAZ areas with lower values showed slightly higher acircularity values. We also have a consistent and coherent set of segmentations with which to continue our research. Conclusions: Manual segmentations of FAZ are generally carried out with little attention to the consistency of the measurements. A novel criterion for segmenting the FAZ allows segmentations made by different observers to be more similar

Capacidad diagnóstica del parámetro “Apertura de la Membrana de Bruch – Mínima Anchura del Anillo” en el glaucoma

El glaucoma es una neuropatía óptica progresiva caracterizada por cambios morfológicos de la papila y de la capa de fibras nerviosas de la retina. Además, asocia una pérdida de campo visual a medida que la enfermedad avanza, incluso pudiendo llegar a la ceguera en los casos más avanzados. Debido a que la neuropatía óptica glaucomatosa suele ser asintomática en sus fases iniciales, tiene suma importancia la prevención y el diagnóstico precoz de la enfermedad con el fin de evitar daños irreversibles en el nervio óptico. Una de las herramientas más utilizadas para evaluar la afectación del nervio óptico en el glaucoma de una manera objetiva es la Tomografía de Coherencia Óptica (OCT). En los últimos años se han producido avances en tecnología y en técnicas diagnósticas de la OCT que han hecho posible incorporar nuevos protocolos como el de la Apertura de la Membrana de Bruch - Mínima Anchura del Anillo (BMO-MRW). Este protocolo por ejemplo puede suponer una posible ventaja diagnóstica para papilas oblicuas o de tamaños inusuales frente al protocolo tradicional. Con este trabajo se pretende comparar la capacidad diagnóstica del protocolo BMO-MRW frente al protocolo tradicional de evaluación de capa de fibras nerviosas de la retina peripapilar en pacientes con glaucoma leve y sujetos sanos.<br /

Choroidal and Retinal Thicknesses in Type 2 Diabetes Mellitus with Moderate Diabetic Retinopathy Measured by Swept Source OCT

Background: To study choroidal thickness (CT) in type 2 diabetes mellitus (DM2) patients with moderate diabetic retinopathy (DR) and to correlate with changes in retinal thickness (RT) with swept-source OCT (SS-OCT) compared to healthy subjects. Methods: Fifty-four DM2 patients with moderate DR without diabetic macular edema (DME) and 73 age-matched healthy subjects were evaluated using SS-OCT to measure changes in total RT and CT in the nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid. Results: The mean age was 64.06 ± 11.98 years and 60.79 ± 8.62 years in the diabetic and control groups, respectively. Total RT showed statistically significant differences in the temporal inner area, with higher values in the DM2 group (p = 0.010). CT did not show differences between the groups. There was a significant negative correlation between RT and age in all of the outer ETDRS areas and a positive significant correlation in the central area for the DM2 group. There was also a negative significant correlation between CT and age in all of the ETDRS areas except for the inferior inner area. In the DM2 group, a negative correlation was observed between RT and CT in the central area (p = 0.039) and in both horizontal parafoveal areas (temporal inner, p = 0.028; nasal inner, p= 0.003). Conclusion: DM2 patients with moderate DR have no changes with regard to CT. Both CT and RT decreased with age in DM2, showing a negative correlation between these factors in the central and horizontal parafoveal areas of the ETDRS grid

Retinal Vascularization Abnormalities Studied by Optical Coherence Tomography Angiography (OCTA) in Type 2 Diabetic Patients with Moderate Diabetic Retinopathy

Diabetic retinopathy (DR) is the most severe and frequent retinal vascular disease that causes significant visual loss on a global scale. The purpose of our study was to evaluate retinal vascularization in the superficial capillary plexus (SCP), the deep capillary plexus (DCP) and the choriocapillaris (CC) and changes in the foveal avascular zone (FAZ) by optical tomography angiography (OCTA) in patients with type 2 diabetes mellitus (DM2) with moderate DR but without diabetic macular oedema (DME). Fifty-four eyes of DM2 with moderate DR (level 43 in the ETDRS scale) and without DME and 73 age-matched healthy eyes were evaluated using OCTA with swept-source (SS)-OCT to measure microvascularization changes in SCP, DCP, CC and the FAZ. The mean ages were 64.06 ± 11.98 and 60.79 ± 8.62 years in the DM2 and control groups, respectively. Visual acuity (VA) was lower in the DM2 patients (p = 0.001), OCTA showed changes in the SCP with a significant diminution in the vascular density and the FAZ area was significantly higher compared to healthy controls, with p &lt; 0.001 at the SCP level. The most prevalent anatomical alterations were peripheral disruption in the SCP (83.3%), microaneurysms (MA) in the SCP and in the DCP (79.6% and 79.6%, respectively) and flow changes in the DCP (81.5%). A significant positive correlation was observed between the DM2 duration and the FAZ area in the SCP (0.304 with p = 0.025). A significant negative correlation was also found between age and CC central perfusion (p &lt; 0.001). In summary, a decrease in the vascular density in DM2 patients with moderate DR without DME was observed, especially at the retinal SPC level. Furthermore, it was found that the FAZ was increased in the DM2 group in both retinal plexuses and was greater in the SCP group

Lighting-Induced Changes in Central and Peripheral Retinal Thickness and Shape after Short-Term Reading Tasks in Electronic Devices

Background: To assess retinal and optical changes associated with near vision reading for different lighting conditions in electronic screens. Methods: Twenty-four young healthy subjects participated in the study; an iPad and an Ebook were chosen as stimuli for 5 min of reading task with different lighting conditions. Central and peripheral retinal thicknesses in the macular ETDRS areas by optical coherence tomography were analyzed. Results: Significant differences were found between basal retinal thickness and retinal thickness after reading with iPad and high illumination, in the N6 (p = 0.021) and I6 (p = 0.049) areas, and low illumination (S3: p = 0.008, N3: p = 0.018, I3: p = 0.021, N6: p = 0.018 and I6: p = 0.020), being thinner after reading. The same trend was observed after reading with an Ebook and high lighting in the N3 (p = 0.037) and N6 (p = 0.028). For low lighting conditions, only retinal thinning was observed. After reading, retinal shape analysis revealed significant changes from computed basal eccentricity for high lighting conditions only. At the periphery, those differences in eccentricity values were statistically significant for both lighting conditions. Conclusions: Young people can recover visual quality after 5 min of reading tasks at different lighting levels on electronic devices, while peripheral retinal expansion remains altered, especially at low lighting levels

Changes in Inner Retina Thickness and Macular Sensitivity in Patients with Type 2 Diabetes with Moderate Diabetic Retinopathy

The increase in diabetic retinopathy (DR) prevalence demonstrates the need for the determination of biomarkers for assessing disease development to obtain an early diagnosis and stop its progression. We aimed to analyse total retinal (RT) and inner retinal layer (IRL) thicknesses in type 2 diabetes mellitus (DM2) patients and correlate these results with retinal sensitivity using swept-source OCT (SS-OCT) and microperimetry. For this purpose, a total of 54 DM2 subjects with moderate diabetic retinopathy (DR) with no signs of diabetic macular oedema (DME) and 73 age-matched healthy individuals were assessed using SS-OCT to quantify retinal thickness in the nine macular areas of the ETDRS grid. Retinal sensitivity was measured via microperimetry with a Macular Integrity Assessment Device (MAIA). The mean ages were 64.06 ± 11.98 years for the DM2 group and 60.79 ± 8.62 years for the control group. DM2 patients presented lower visual acuity (p p = 0.01). The retinal nerve fibre layer (RNFL) was significantly lower in the outer nasal area (50.38 ± 8.20 μm vs. 45.17 ± 11.25 μm, p = 0.005) in ganglion cells and inner plexiform layers (GCL+) in DM2. A positive correlation between the LDL-C and RNFL and a negative correlation between HDL-C levels and the inner temporal and central RNFL thickness were detected. The central (p = 0.021) and inner nasal (p = 0.01) areas were negatively correlated between the RNFL and MAIA, while GCL++ was positively correlated with the outer inferior (p = 0.015) and outer nasal areas (p = 0.024). Retinal sensitivity and macular RNFL thickness decrease in DM2 patients with moderate DR with no DME, and this study enables an accurate approach to this disease with personalised assessment based on the DR course or stage. Thus, GCL+ and GCL++ thinning may support ganglion cell loss before the RNFL is affected