Abstract
Abstract: :
Background: Our clinical observation reveales that myopia tends to appear or accelerate during the years of childhood and/or puberty when the growth hormone (GH) is secreted at its highest level. Purpose: In order to establish a possible connection between myopia and GH , we evaluated the effect of GH on the axial elongation of the eye globe in laboratory rats. Methods: A group of 24 albino Wistar rats, at the age of 21 days, half males and half females, were included in the presented study. Twelve rats were treated with hGH (Biotechnology Ltd,Israel) by intraperitoneal injection of 1mg/Kg for 6 consecutive days.A second group of twelve rats was identically injected with 1ml/Kg of 0,9% N/S solution, and used as the control group.An every day measurement of the body weight,axial lenght of the skull,posterior limb lenght and equatorial diameter of the eyes were measured. At two terms animals were sacrificed by a lethal dose of pentobarbital and the eyes were enuclated for axial lenght measurement.Five rats of each group were sacrificed at 16 days following the injections and the remainig seven rats in each group were sacrificed at 36 days following the injections. Results: At the 36 days term, we found a signifficant difference in the axial lenght of the eyes between the GH injected rats and the saline injected rats. Mean axial lenght in the GH group : 0.6245+/–0.0079 cm Mean axial lenght in saline group : 0.5932+/– 0.0149 cm P= 0.0031, Wilcoxon ranksum test. We did not find any signifficant difference between the groups as regarding to other evaluated parameters, as mentioned in the methods. Conclusions: Systemic GH administration in laboratory rats,which mimic the increased secretion of GH in childhooh and puberty, induced axial elongation of the eye globes in rats. Thereby, we may suppose that GH may be one of the mediators for the appearance and progression of myopia in humans.
Keywords: myopia • growth factors/growth factor receptors • refractive error development