To assess full-field electroretinogram findings in long-term type 1 diabetes patients without diabetic retinopathy. Prospective study including 46 eyes of 23 patients with type 1 diabetes and 46 age-matched healthy eyes evaluated by the RETI-port/scan21 and the portable system RETeval following ISCEV guidelines. The average duration of diabetes was 28.88 ± 8.04 years. In scotopic conditions, using the RETI-port/scan21, diabetic patients showed an increase in b-wave implicit time (IT) (p = 0.017) with the lowest stimuli; a diminished b-wave amplitude (p = 0.005) in the mixed response, an increased IT (p = 0.004) with the high-intensity stimuli and an OP2 increased IT (p = 0.008) and decreased amplitude (p = 0.002). Under photopic conditions, b-wave amplitude was lower (p < 0.001) and 30-Hz flicker response was diminished (p = 0.021). Using the RETeval, in scotopic conditions, diabetic patients showed a reduction in the rod b-wave amplitude (p = 0.009), an increase in a-wave IT with the 280 Td.s stimulus (p = 0.005). OP2 had an increased IT and diminished amplitude (p = 0.003 and p = 0.002 respectively). 16 Td.s flicker showed an increased IT (p = 0.008) and diminished amplitude (p = 0.048). Despite variations in values between both systems, nearly all results displayed positive correlations. Long-term type 1 diabetes patients without diabetic retinopathy exhibit alterations in scotopic conditions, as evidenced by both conventional and portable electroretinogram devices. These findings suggest a modified retinal function, particularly in rod-driven pathways, even in the absence of vascular signs.

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 < 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 < 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.

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 < 0.001) and a thicker RT (260.70 ± 19.22 μm in the control group vs. 271.90 ± 37.61 μm in the DM2 group, 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.

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.

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.

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.