Biomechanical Properties of the Cornea Using a Dynamic Scheimpflug Analyzer in Healthy Eyes

PURPOSE: To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. MATERIALS AND METHODS: In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. RESULTS: This study included 217 eyes of 118 participants (20–81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20–44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased Corvis-IOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20–44 years, and over 44 years). CONCLUSION: We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.

Zinc plasmático, cobre sérico y zinc y cobre eritrocitarios en adultos sanos de Buenos Aires / Plasmatic zinc, serum copper and erythrocyte zinc and copper levels in healthy adult people living in Buenos Aires

Se estudiaron adultos, clínicamente sanos, 21 varones (V) y 19 mujeres (M), de: edad (años): V: 48±14 (28-78); M: 41±14 (23-66); Índice de masa corporal (kg/m²): V: 26,7±2,3 (23,1-31,9); M: 22,2±3,5 (19,3-29,6). Se realizó una encuesta nutricional y se extrajo sangre en ayunas. Se realizaron las determinaciones de rutina del laboratorio clínico. Se determinó zinc en plasma (ZnPl), cobre en suero (CuS); en eritrocitos: Zinc (ZnGR) y cobre (CuGR), por espectrometría de absorción atómica. La totalidad de los V y M presentaron ingestas adecuadas de energía, proteínas, Zn y Cu. Los resultados expresados como: promedio ± desvío estándar y rangos fueron: ZnPl (μg/dL): V: 93±27 (49-161); M: 79±28 (42-157); ZnGR (μg/dL): V: 1.380±210 (1.110-2.010); M: 1.350±130 (1.090-1.520); CuS (μg/dL): V: 89±20 (40- 122); M: 93±28 (45-157). CuGR (μg/dL): V: 59±12 (37-78); M: 63±19 (30- 110). No se evidenciaron diferencias significativas entre V y M. Los resultados para la población estudiada fueron, percentilos 5 y 95, respectivamente: ZnPl: 49 a 131 μg/dL; ZnGR: 1.130 a 1.610 μg/dL; Zn/Hb: 34,4 a 47,5 μg/g; CuS: 45 a 124 μg/dL; CuGR: 36 a 78 μg/dL. Los valores de ZnPl y CuS se encuadraron dentro de los rangos de valores de referencia internacionales, sin diferencias significativas de acuerdo con el género.

Two groups of adult healthy people were studied: 21 males (M) and 19 females (F). Mean age (ys) was: M: 48±14 (28-78); F: 41±14 (23-66); body mass index (Kg/m²) was: M: 26.7±2.3 (23.1-31.9); F: 22.2±3.5 (19.3-29.6). A nutritional survey was recorded and mean daily intake of energy, protein, Zinc (Zn) and Copper (Cu) were calculated. Fasting blood samples were obtained in order to determine Hemoglobin (Hb), plasmatic Zn (PlZn), serum Cu (SCu), erythrocyte Zn (EZn) and erythrocyte Cu (ECu) levels. Zn and Cu were determined by AAS. Results were: mean±SD and ranges: PlZn (μg/dL): M: 93±27 (49-161); F: 79±28 (42-157); EZn (μg/dL): M: 1380±210 (1110-2010); F: 1350±130 (1090-1520); SCu (μg/dL): M: 89±20 (40-122); F: 93±28 (45-157). ECu (μg/dL): M: 59±12 (37-78); F: 63±19 (30-110). All individuals presented adequate intake of energy, protein, Zn and Cu. There were no significant differences between M and F for PlZn, EZn, Zn/Hb ratio, SCu and ECu. The results for the adult healthy population in Argentina, and which were in accordance with the international published values were: (percentiles 5 y 95, respectively): PlZn: 49 - 131 μg/dL; EZn: 1130 - 1610 μg/dL; Zn/Hb: 34,4 - 47,5 μg/g; SCu: 45 - 124 μg/dL; ECu: 36 - 78 μg/dL.