Abstract
Abstract: :
Purpose: To study whether the light on premature eyes is a key factor of myopia, we investigated ocular growth and refractive error development in neonatal mice with lighting before natural eye opening. Methods: 280 C57BL/6J mice were used and divided into five groups: (1) group 1, the right eyelids were separated by operation at postnatal day 4, 6, 8, 10 ,11, and 12 , respectively, (2) group 2, to research the correlation between ROP and refractive error, the mice from ROP model were underwent the same processes as group 1, (3) group 3, mice accepted the same operation as group 1, but were raised in dark, (4) group 4, mice with eyelids opened raised in dark after natural eye opening, (5) group 5,age–matched untreated mice as control. The refraction of animals was checked at the day of natural eye opening and other scheduled time. Then, eyes were enucleated, eyeball weight, lens weight, ocular axial dimensions, and lens thickness were measured. Results: Although the right eye of mouse in group1 developed significant myopia compared with the left eye, the degree of relative myopia was –0.77±0.09 D, –7.12±0.14 D, –6.35±0.11 D, –5.40±0.11 D, –4.91±0.09 D, and –3.81±0.21 D, respectively at P4, P6, P8, P10, P11, and P12, they all recovered to normal under the normal light environment. Myopia in group 3 was not found. However, myopia in group 4 occured and still existed through adulthood. The animals which eyelids were opened at P11 in ROP model group also had relative myopia and the degree was –8.25±0.17 D, which was obviously higher than that of the animal with the same age in group 1 (t=75.181, P<0.01). Compared with the control eye, the right eye was significantly smaller, for example, the difference of both eye weight, lens weight, and axial dimensions measured at P14 from the animals which eyelids were separated at P4 were 0.44±0.07 mg (P<0.01), 0.09±0.03 mg(P<0.05), and 0.06±0.01 mm (P<0.05), respectively. But there was no change in lens thickness (P>0.05). Conclusions: Lighting stimulation in advance induced non–axial and reversible myopia. The earlier the mouse accepted lighting, the higher the degree of myopia was and also took longer time to recover. The myopia was much severer in mice with eyelids opened in advance and ROP. According to these animal models, lighting may be a key factor to myopia of premature infants and ROP may promote the form and development of myopia of premature infants.
Keywords: myopia • refractive error development • retinopathy of prematurity