Abstract
Abstract: :
Purpose: To induce form deprivation myopia in fish and investigate the role of the lens in refractive error development. Methods: Tilapia (Oreochromis niloticus), about 4 months old and from 26 to 63grams were divided into three groups. Translucent goggles were directly sutured over the right eye for 4 weeks to induce form deprivation myopia while the left eye served as an untreated contralateral control. Refractive state was measured by retinoscopy. Ocular dimensions were determined from frozen sections and with ultrasound biomicroscopy, while a scanning laser system was used to determine the optical quality of excised lenses. Results: All the deprived fish eyes developed significant amounts of myopia ranging from –3.75 to 26.25 diopters (D), with the average amounting to 10.27±1.14 D, after four weeks of form deprivation treatment. Eye dimension measurements show that the vitreous and anterior chambers of the treated eye are significantly longer axially than those of the contralateral eyes. No significant change in optical quality was found between lenses of the myopic and non–myopic eyes. The fish recovered completely from the myopia five days after the goggle was removed. Conclusions: Form deprivation myopia can be induced in lower vertebrates which are capable of lifelong growth and thus the visual environment is an important factor controlling ocular development in lower vertebrates as well as in higher ones and eye development is not strictly genetically determined. This study also indicates that lens growth and optical development is independent from the refractive development of the whole eye.
Keywords: myopia • refractive error development