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First Author: J.Alió SPAIN
Co Author(s): A. Abbouda P. Peña-Garcia
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Several studies described the effect of aging on anterior chamber, crystalline lens shape and volume modification. The lens thickness increases of 18 to 20 ?m every year. This means that after 20 years, the anterior pole of the crystalline lens has moved forward by 400 ?m. The current study was performed to investigate the change in anterior chamber in patients implanted with ZB5M0 in relation to the age and crystalline rise during the follow up.
Patients were evaluated using AS-OCT. The measurements were evaluated using the refractive tools provided by the manufacturer: distance between the anterior surface of the center of the PIOL and the corneal endothelium, distance between the posterior surface of the center of the PIOL and the anterior surface of the crystalline lens and distances between the edges (nasal and temporal side) of the PIOL and the corneal endothelium. Three anterior segment parameters, including horizontal anterior chamber width (ACW, measured from the recesses of the iridocorneal angle on each side of the eyes optical axis),anterior chamber depth (ACD, measured from the central anterior corneal epithelium to the anterior crystalline lens capsule) and CLR (crystalline lens rise measured by the anteroposterior distance between the anterior face of the crystalline lens and the recess-to-recess line).
Significative association was found between crystalline rise and age at the end of follow up.( Spearman ? = 0.47; p<0.02). Linear regression analysis showed a positive correlation between crystalline rise and age. (r2=0.22; p<0.02). Anterior chamber depth showed a negative correlation with the age (? -0.28, p<0.19). Linear regression evidenced a negative association. (r2=0.079;p<0.19). The distance between PIOL-endothelium also had a negative correlation with the age (? -0.14, p<0.56) and weak negative trend was evidenced by linear regression. (r2=0.02;p<0.56). A positive correlation was found with time of PIOLS implanted and ECL. ( ?= 0.6; p<0.006) also the linear regression showed a significance correlation between these variables.(r2=0.36; p<0.006). Linear regression evidenced a negative association between the amount of ECL and anterior chamber depth. (r2=0.19 ;p<0.05), crystalline size(r2=0.05 ;p<0.1) and endothelial-PIOL distance(r2=0.16 ;p<0.08). The variables which showed a significance difference between two groups of age (9 eyes in the group of 40-50 year old and 14 eyes >50) were the crystalline rise (p<0.01) and the distance between endothelial and PIOLs nasal edge (p< 0.01) .According to refractive status before surgery.( 16 eyes ?20 ? and 7 eyes ?21?).Significant difference was found between PIOL-endothelium temporal edge and crystalline rise. (p<0.02).
The effect of the aging reduce the distance between the PIOLs and the tissue of the eye and could predispose a patient to corneal endothelial cell loss or cataract. A strong and significant correlation was found between ACD and the number of EC at the end of the follow up (r=0.627, p=0.001). This correlation shows that the amount of EC at the end is higher in eyes whose AC is deeper. This association is just known, ACD is an important measurement to take before the PIOLs implantation because if its deep can prevent ECL. The spherical equivalent previous to the PIOL implantation is strongly related with the value of the ACD at the end of the follow up (r=0.650, p=0.002). Cataract formation was more frequent in high myopic patients, the higher is the myopia at the beginning the lower is the ACD at the end of follow up. A significant correlation was found between ACD and time of PIOL implantation (r=-0.478, p<0.021). So, the longer the time of implantation, higher is the risk of cataract and the lower is the ACD. The ECC showed strong and significant correlations with two variables: preoperative spherical equivalent (r= 0.692, p=0.001), and time of implantation (TI), (r=0.671, p<0.001).The predictive model show that, , the PIOL model analyzed will have to be explanted before 30 years of implantation because the ECC would be less than 600 cells/mm2 in patients with a preoperative SE of -25D or before 40 years in patients with SE of -20D. Furthemore the safety zone of 1.5 mm between endothelium and the lens will not be respected after 20 years of implantation in patients with a preoperative SE of -20D or after 15 years in patients with a SE of-25D.