Retinal oxygen saturation is associated with HbA1c but not with short-term diabetes control, internal environment, smoking and mild retinopathy - ROXINEGLYD study.

PURPOSE: Purpose of this prospective uncontrolled single-centre pilot study was to find an association of retinal oxygen saturation (SatO2 ) with acid-base balance (ABB), carboxyhaemoglobin concentration, current plasma glucose concentration (PG), mean PG and PG variability over the last 72 hr, haemoglobin A1c (HbA1c), and other conditions. METHODS: Forty-one adults (17 men) with type 1 (N = 14) or type 2 (N = 27) diabetes mellitus, age 48.6 ± 13.5 years, diabetes duration 9 (0.1-36) years, BMI 29.4 ± 6.3 kg/m2 , and HbA1c 52 ± 12.7 mmol/mol completed the study. The 4-day study comprised two visits (Day l, Day 4) including 72 hr of continuous glucose monitoring (CGM) by iPro® 2 Professional CGM (Medtronic, MiniMed, Inc., Northridge, CA, USA). Retinal oximeter Oxymap T1 (Oxymap ehf., Reykjavik, Iceland) was used to assess SatO2 . RESULTS: Wilcoxon signed-rank test showed no SatO2 difference between eyes and visits. Spearman's correlation analysis revealed a significant correlation between arterial SatO2 and PG variability in type 2 diabetes mellitus, a positive correlation of venous SatO2 with HbA1c and with finger pulse oximetry. However, no correlation of SatO2 with ABB, carboxyhaemoglobin, current PG, mean PG over the 72 hr, age, diabetes duration, BMI, lipoproteinaemia, body temperature, systolic and diastolic blood pressure, heart rate, central retinal thickness and retinal nerve fibre layer thickness was found. CONCLUSION: This study confirmed the association of venous SatO2 with long-term but not with short-term diabetes control, ABB and other conditions. The increased SatO2 and questionable impact of PG variability on retinal SatO2 is a research challenge.

Age-related changes in the lateral lipid distribution in a human lens described by mass spectrometry imaging.

The lateral lipid distribution in eye lenses of three human donors were studied by matrix-assisted laser desorption ionization imaging mass spectrometry using a high mass resolution. By using exact mass measurements this study shows the relationship between the aging process and the number of lipids detected as well as between aging and the abundance of products derived from sphingomyelins by hydrolysis. Variable lipid composition was also observed in the nuclear, barrier, or cortex regions of the lens samples. This is the first study that suggests the distribution of lysolipids as a potential biomarker panel for the aging of human lens tissue.

The importance of angle kappa evaluation for implantation of diffractive multifocal intra-ocular lenses using pseudophakic eye model.

PURPOSE: To determine the critical value of the angle kappa in connection with a higher risk of photic phenomena for the AcrySof ReSTOR and Tecnis multifocal intra-ocular lens (MIOL) on a standardized pseudophakic eye model. To analyse the impact of biometric value changes on the critical angle kappa. METHODS: Geometrical optic rules applied to a suitable optical model of the pseudophakic eye were used to calculate the critical value of the angle kappa for the Tecnis and three types of the AcrySof ReSTOR MIOLs. The angle kappa was defined as critical if the incident ray passed through the first ring's edge area. The influence of different positive optical corneal power (K), effective lens position (ELP) and axial length (AL) on the critical angle kappa (κc) was investigated. The dependence of κc on one of the parameters was studied for standardized values of the remaining parameters. RESULTS: The highest value of the critical angle kappa was evaluated for the Tecnis MIOL. The increase in ELP and K caused an increase in κc under the given conditions. On the contrary, an increase in AL led to lower values of κc. CONCLUSION: We demonstrated the dependence of the critical angle kappa on the central part of the MIOL and on biometric parameters of the eye, especially on the effective lens position. According to these results, we conclude that shallow anterior chamber depth in connection with a higher angle kappa is an important risk factor for pronounced photic phenomena after implantation of a diffractive MIOL.