Evaluation of aqueous-deficient and evaporative dry eye cases with confocal microscopy.

INTRODUCTION: Dry eye disease (DED) is an important health problem affecting hundreds of millions of people worldwide. In vivo confocal microscopy (IVCM) is a non-invasive imaging tool that can visualize ocular surface diseases. In this study, we aimed to evaluate corneal structures and inflammatory cells with IVCM in DED patients. MATERIAL AND METHODS: The patients were divided into three subgroups: group 1, consisting of 22 patients with aqueous tear insufficiency; group 2, consisting of 21 patients with evaporative type DED; and group 3, consisting of 20 healthy patients. Imaging was performed with IVCM. The corneal epithelium, nerves, stroma, endothelial and inflammatory cells were compared between groups. RESULTS: There was a significant decrease in corneal epithelial cell density in cases with DED, and there was a significant increase in corneal basal epithelial cell density in the aqueous-deficient type. Keratocyte density was significantly increased in the aqueous-deficient type. A significant decrease in the number and density of sub-basal nerves was found in aqueous-deficient cases, and an increase was found in neural pilling and folding. Dendritic cell density, size, number and area were significantly increased in the aqueous-deficient type. There was also decreased corneal endothelial cell density in DED. CONCLUSION: We evaluated pathological changes in DED on the corneal surface by IVCM. This methodology is valuable in terms of objectively evaluating how the corneal surface is affected in accordance with disease severity and in predicting poor response to treatment.

Can expected pCO2 be calculated by pCO2=HCO3+15 formula in central venous blood gas samples?

OBJECTIVE: In mixed acid-base disorders, it is essential to identify the dominant disorder, either metabolic or respiratory. The calculation of expected partial carbondioxide (pCO2) value obtained from arterial blood gas sample can give a clue to the physician about the main disorder. There are several formulas to calculate the expected pCO2 which are not practical to use and require an arterial blood gas sample. The aim of this study is to investigate whether expected pCO2 could be calculated with a simple formula by adding 15 to the bicarbonate (HCO3) value obtained from a central venous blood gas sample. PATIENTS AND METHODS: 50 (42.7%) female and 67 (57.3%) male patients aged 18 years and older, hospitalized in the Intensive Care Unit (ICU) between January 2022 and June 2022, whose arterial and central venous blood gas samples were drawn at the same time, were included in this study. Expected pCO2 values were calculated with both Winter's (pCO2 = 1.5 × HCO3 + 8) and simple (pCO2 = HCO3 + 15) formulas from the data obtained from arterial and jugular central venous blood gas samples. RESULTS: A statistically significant strong positive correlation was identified between arterial and venous expected pCO2 values, which were calculated by using both Winter's and simple formulas [Pearson's correlation coefficient (r) = 1, p<0.001]. CONCLUSIONS: In ICU patients, (pCO2 = HCO3 + 15) formula can be used to calculate expected pCO2 in central venous blood gas samples to identify the primary disorder as metabolic or respiratory in mixed acid-base disorders.

Quantitative OCT angiography of the retina and choroid in non-ocular sarcoidosis.

OBJECTIVE: The aim of the study was to evaluate retinal and choroidal microvascular morphological changes in non-ocular sarcoidosis (NOS) patients using optical coherence tomography angiography (OCTA) and compare the results to age- and gender-matched healthy individuals. PATIENTS AND METHODS: This study included 37 NOS patients (group 1, 37 right eyes) referred to the Ophthalmology Department between 2019 and 2021, as well as 31 healthy individuals (group 2, 31 right eyes). Non-ocular sarcoidosis was defined as sarcoidosis confirmed by a positive lung X-ray and biopsy without ocular manifestation. All participants underwent a comprehensive ophthalmic examination. The SPECTRALIS® OCT was used for both fundus photography and macular analysis. All OCTA procedures were performed in the Angio Retina mode (6.0x6.0 mm) to assess retinal and choroidal microvascular morphology. RESULTS: Groups 1 and 2 had mean ages of 46.41±12.52 and 47.55±13.81 years, respectively (p=0.482). Group 1 had significantly increased superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel densities (VDs) in whole (p=0.059, 0.016), parafoveal (p=0.051, 0.015), and perifoveal (p=0.060, 0.010) regions relative to group 2. Group 1 was also associated with increased foveal avascular zone (FAZ) area (p=0.196), FAZ circumference (p=0.262), and foveal VD in 300 µm wide regions surrounding FAZ (p=0.003) relative to group 2. The outer retinal (p=0.712) and choriocapillaris (p=0.684) flows did not differ significantly between the two groups. CONCLUSIONS: Quantitative OCTA analysis revealed a higher tendency for retinal and choroidal microvascular morphological changes in NOS patients, demonstrating the potential of this novel, non-invasive imaging technology, which may provide sensitive and reliable results without using contrast materials.