Impact of COVID-19 pandemic on the ocular surface

BACKGROUND There have been increased reports of dry eyes in the coronavirus disease 2019(COVID-19) pandemic era.AIM To analyze the differences in tear film properties from pre-and post-pandemic of the COVID-19 era.METHODS It was a retrospective comparative study.Patients were divided into three groups according to the data of multimodal ocular surface evaluation:(1) Group 1 if it was before Portugal lockdown decision(from August 2019 to March 2020);(2) Group 2 if it was after Portugal lockdown decision but without mask mandate(from April 2020 to October 2020);and(3) Group 3 if it was after Portugal lockdown but with mask mandate in health public highway(from November 2020 to April 2021).The following variables were analyzed:Lipid layer thickness,blink rate,Schirmer test,tear meniscus height,tear osmolarity,non-invasive break-up time,and loss area of the meibomian glands.RESULTS The study included 548 eyes of 274 patients,aged 18 years to 89 years,with a mean age of 66.15 ± 13.40 years at the time of multimodal ocular surface evaluation.Compared to group 1:(1) Mean lipid layer thickness was better in group 2(P = 0.001) and group 3(P < 0.001);(2) Schirmer test was similar in group 2(P = 0.576) and better in group 3(P = 0.002);(3) Tear osmolarity and loss area of the meibomian glands were worse in group 2(P = 0.031 and P < 0.001,respectively) and in group 3(both with P < 0.001);(4) Blink rate and tear meniscus height were similar in group 2(P = 0.821 and P = 0.370,respectively) and worse in group 3(P < 0.001 and P = 0.038,respectively);and(5) Non-invasive break-up time was worse in group 2(P = 0.030) and similar in group 3(P = 0.263).CONCLUSION Our study demonstrated that differences existed in tear film properties comparing data from the pre-and post-pandemic of the COVID-19 era.

The influence of the blood pressure on the venous cerebral flow measured by magnetic susceptibility (SWI) technique

Susceptibility Weighted Image (SWI) is a Magnetic Resonance Imaging (MRI) technique that combines high spatial resolution and sensitivity to magnetic susceptibility differences between tissues, it is extremely sensitive to venous blood due to its iron content of deoxyhemoglobin. The aim of this study was to evaluate the differences in the cerebral venous vasculature produced by the value’s variation of blood pressure. 20 subjects (10 hypertensive and 10 normotensive patients) underwent a MRI system with field strength of 1.5 T using a synergy head coil (7 channels). The obtained sequences were T1w, T2w-FLAIR, T2* and SWI. The value of Contrast-to-Noise Ratio (CNR) was assessed in MinIP (Minimum Intensity Projection) and Magnitude images, through drawing free hand ROIs in venous structures: Superior Sagittal Sinus (SSS) Internal Cerebral Vein (ICV) and Sinus Confluence (SC). The obtained values were presented in descriptive statistics-quartiles and extremes diagrams. The results were compared between groups. CNR shown higher values for normotensive group in MinIP (108.89 ± 6.907) to ICV;(238.73 ± 18.556) to SC and (239.384 ± 52.303) to SSS. These values are bigger than images from Hypertensive group about 46 au in average. Comparing the results of Magnitude and MinIP images, there were obtained lower CNR values for the hypertensive group. There were differences in the CNR values between both groups, being these values more expressive in the large vessels-SSS and SC. The SWI is a potential technique to evaluate and characterize the blood pressure variation in the studied vessels adding a physiological perspective to MRI and giving a new approach to the radiological vascular studies.