Plasma Metabolomic Profiles Associated with Three-Year Progression of Age-Related Macular Degeneration

Plasma metabolomic profiles have been shown to be associated with age-related macular degeneration (AMD) and its severity stages. However, all studies performed to date have been cross-sectional and have not assessed progression of AMD. This prospective, longitudinal, pilot study analyzes, for the first time, the association between plasma metabolomic profiles and progression of AMD over a 3-year period. At baseline and 3 years later, subjects with AMD (n = 108 eyes) and controls (n = 45 eyes) were imaged with color fundus photos for AMD staging and tested for retinal function with dark adaptation (DA). Fasting plasma samples were also collected for metabolomic profiling. AMD progression was considered present if AMD stage at 3 years was more advanced than at baseline (n = 26 eyes, 17%). Results showed that, of the metabolites measured at baseline, eight were associated with 3-year AMD progression (p < 0.01) and 19 (p < 0.01) with changes in DA. Additionally, changes in the levels (i.e., between 3 years and baseline) of 6 and 17 metabolites demonstrated significant associations (p < 0.01) with AMD progression and DA, respectively. In conclusion, plasma metabolomic profiles are associated with clinical and functional progression of AMD at 3 years. These findings contribute to our understanding of mechanisms of AMD progression and the identification of potential therapeutics for this blinding disease.

Application of Angio Optical Coherence Tomography and Flash Electroretinogram in the Study of Retinal Morphology and Function in High Myopia

Purpose: Using optical coherence tomography (OCTA) and flash electroretinography (F-ERG), we investigated changes to the retinal micromorphology and the overall function of the retina in eyes with different degrees of high myopia. Design: Case-control study. Participants: A total of 64 cases of 118 eyes with axial high myopia with diopters ranging from -−6.0 D to −15.0D were included in the study. The individuals were 18-40 years old.Methods: Subjects were divided into three groups according to the axial length (AL) of the eye and the spherical equivalent (SE)of the lens: the high myopia group (AL: ≤26 mm and SE: −6.0D to −9.0D) with 32 eyes, the ultra-high myopia group (AL: 26-28 mm and SE: -9.25D to -12.0D) with 43 eyes, and the extremely high myopia group (AL: ≥28 mm and SE: −12.25D to −15.0D) with 43 eyes. We used the OCTA measurements macular foveal retinal thickness (MRT), foveal avascular zone (FAZ), and superficial macular and deep retinal microvascular density, and the F-ERG measurements retinal dark-adaptation a-wave and b-wave, oscillation potential (OP) wave, light adaptation a-wave and b-wave, and 30-Hz flicker light amplitudes, which represent the functional state of the retina.Results: The differences in retinal thickness in the macular area between the three groups were only statistically significant within 1 mm of the fovea (P = 0.006). MRT was positively correlated with AL (r = 0.278, P = 0.002) and negatively correlated with SE (R = −0.200, P = 0.031). The difference in the FAZ area between the three groups was also statistically significant (P = 0.036), and FAZ was negatively correlated with AL (r = −0.377, p < 0.001) and positively correlated with SE (r = 0.192, P < 0.5). Both the superficial and deep blood flow density of the macular fovea were positively correlated with AL (p < 0.001). The superficial parafoveal blood flow density was negatively correlated with AL (r = −0.280, P = 0.002) but positively correlated with SE (R = 0.254, P = 0.006). The overall blood flow density of the deep retina, the parafoveal blood flow density, and the blood flow density around the fovea were negatively correlated with AL (p < 0.001) and positively correlated with myopic SE (p < 0.001). The dark-adaptation b-wave, maximum comprehensive response a-wave and b-wave, OP wave, bright-adaptation a-wave and b-wave, and 30-Hz flicker amplitudes of the retina were negatively correlated with AL and positively correlated with SE. The amplitudes of light adaptation a-wave and b-wave were[1] negatively correlated with the foveal avascular density (p < 0.001), and the average amplitude of the OP wave was positively correlated with the superficial retinal avascular density (p < 0.001).Conclusions: Before obvious pathological changes or central vision damage, the morphology and function of the macular area show subtle changes in patients with high myopia. As the degree of myopia increases and the axis of the eye increases, the activity of the cone cells in high myopia eyes decreases and the microvascular circulation in the inner retina and function of inner layer cells, such as non-proa cells, are affected. The changes of retinal dark adaptation are more sensitive than those of bright adaptation, which indicates that retinal rod cell damage may be earlier than cone cell damage in high myopia. Therefore, we believe that the combined use of OCTA and F-ERG can help in the early diagnosis and monitoring of patients at a high risk of myopia and to guide their clinical treatment.Because the p-value is clearly provided, the term “significantly” is not necessary (removed to reduce wordiness).

PSI Open Fluor CAM script for measuring qE component of NPQ in Chlorella vulgaris v1

This is a simple protocol that consists of 1) 10 minutes preillumination with far red light 2) 5 minutes of illumination with actinic light 3) 5 minutes of dark adaptation with far red light qE is calculated as the differe between NPQ_Lss and NPQ_D5 qE=NPQ_Lss-NPQ_D5 qI=NPQ_D5 Protocol to be used with FluorCAM 7.0 on a PSI Open FC 800-O/1010-S. Act 2 - are the white light LED arrays ADD2 - is the far red LED array Camera is placed at ~20 cm above the measured sample. Light intensity uniformity across the 96 well plate was measured according to manufacturer instructions. !Important - protocol only works under weak far red light. Intense far red will interfere with the fluorescence measurement.

Optical coherence tomography angiography application to pigmented iris: Could a new index quantify blood flow?

Purpose: To assess the blood flow and vascular visibility of irises in relation to pigmentation and pupil size, using an anterior segment optical coherence tomography angiography (OCTA). Materials and methods: This is a cross-sectional study. OCTA images were acquired in the nasal and temporal quadrants from a cohort of 30 healthy subjects in photopic (miosis) and scotopic (mydriasis) conditions. Patients were divided according to iris color (less pigmented: group L vs more pigmented: group D). Vascular parameters (vessel density (VD), vessel length density (VLD), fractal dimension (FD)) were applied and compared among groups L and D, location and different pupil status. A novel vascular index called Luminance Index (LI) was developed and applied in order to quantify vascular flow and evaluate its variation in photopic and scotopic conditions. Multivariable analyses were performed to evaluate possible predictors of VD and LI. Results: No differences were found for all vascular measurements (VD, VDL, FD, LI) between nasal and temporal quadrants. All vascular measurements were higher in group L than in group D ( p < 0.05), except for LI and FD in photopic condition. In group L, all vascular parameters increased ( p < 0.001) after dark adaptation. In group D, only LI increased after dark adaptation ( p < 0.001). Pigmentation and iris thickness were significantly associated with VD in scotopic and photopic conditions, and with LI only in scotopic condition. Conclusions: Pigmentation still remains a major issue for vascular visibility. Quantitative and qualitative vascular changes follow pupil size variation. LI could be a new surrogate to quantify blood flow.

Prevalence of electronegative electroretinograms in a healthy adult cohort

ObjectiveAn electronegative electroretinogram (ERG) can indicate important ocular or systemic disease. This study explored the prevalence of electronegative responses to dark-adapted stimuli in a largely healthy cohort.Methods and Analysis211 participants recruited from the TwinsUK cohort underwent ERG testing incorporating international standard (International Society for Clinical Electrophysiology of Vision (ISCEV)) protocols and additional stimuli. Responses were recorded using conductive fibre electrodes, following pupil dilation and 20 min dark adaptation. Responses analysed were to the ISCEV standard and strong flashes (3.0 and 10 cd/m2 s), and to additional white flashes (0.67–67 cd/m2 s). A-wave and b-wave amplitudes were extracted; b:a ratios were calculated and proportions of eyes with ratios<1 were noted.ResultsMean (SD) age was 62.4 (11.4) years (median, 64.3; range 23–86 years). 93% were female. Mean (SD) b:a ratios for right and left eyes, respectively, were 1.86 (0.33) and 1.81 (0.29) for the standard flash, and 1.62 (0.25) and 1.58 (0.23) for the stronger flash; average b:a ratio was lower for the stronger flash (p<0.0001). No waveforms were electronegative. For additional flashes, b:a ratio decreased with increasing flash strength. No electronegative waveforms were seen except in three eyes (0.7%) for the strongest flash; in some cases, drift in the waveform may have artefactually reduced the b:a ratio.ConclusionFor standard dark-adapted stimuli, no participants had electronegative waveforms. The findings support the notion that electronegative waveforms (in response to standard flash strengths) are unusual, and should prompt further investigation.

Assessment of factual measurement times for chlorophyll-a fluorescence in rubber (Hevea brasiliensis) clones

Cahyo AN, Murti RH, Putra ETS, Nuringtyas TR, Fabre D, Montoro P. 2021. Assessment of factual measurement times for chlorophyll-a fluorescence in rubber (Hevea brasiliensis) clones. Biodiversitas 22: 3470-3477. Chlorophyll-a fluorescence is widely used to determine the stress tolerance levels of some plant species. Measurement of chlorophyll-a fluorescence is accurate if the duration of dark adaptation is well defined and optimal Fv/Fm (maximum quantum yield of primary photochemistry/photosynthesis) is achieved. Leaf clips are usually used to darken the leaf prior to measurement. This procedure takes time and limits the use of chlorophyll-a fluorescence parameter in high-throughput screening of genetic populations. This study aimed to determine the most suitable time for the chlorophyll-a fluorescence measurement. This study was carried out on several rubbers (Hevea brasiliensis Müll. Arg.) clones and consisted of two steps. The first step was conducting the measurements at five different times at night: at 7.30, 8.00, 8.30, 9.00, and 9.30 p.m. The second step was conducting the measurements at daytime, which consisted of two factors. The first factor was the measurement time, which was divided into two categories: 7.30 a.m. and 1.30 p.m. The second factor was the duration of dark adaptation using leaf clips, which consisted of nine levels: 0, 15, 30, 45, 60, 75, 90, 105, and 120 min. Additional treatment (measurement at 9.00 p.m. without using leaf clips to darken the leaf) was used as a control. This study revealed that a dark adaptation time of two hours after the sunset was long enough for the rubber leaves chlorophyll-a fluorescence transient to be measured without using leaf clips for the dark adaptation. If the measurement is conducted by 7.30 a.m., the clone RRIM 600, GT1, and SP 217 required 15 min of dark adaptation, whereas clone PB 260 required 60 min of dark adaptation. Furthermore, measurement of chlorophyll-a fluorescence in the afternoon is not recommended due to the potentially high microclimate fluctuation.