| PrefaceMyopia is one kind of the most common eye disease, Which may induce irreversible lesion . The prevention of myopia is of worldwide attention. In the passed 200 years, many hypotheses have been posed about the mechanism of myopia genesis . Recently, the form deprivation theory was set up , based on the fact that axial myopia will occur when there is no clear image on retina during development stage. In this experiment , the myopia models were made in young cats by eyelid suture , and the refractive state , axial length , the histological change in the sclera and retina of these cat eyes were studies to investigate the pathological factors in myopia progress.Materials1. AnimalHealth cat 15 ,4-5 weeks old . Randomly divided in 2 groups , 10 in experimental group, 5 in control group, 5 cats right eyes were sutured ,5 cat's left eyes were sutured, the untreated eyes served asself - control.2. Agent and EquipmentKetamine, Atropine, Experiment animal table , operation equipment , retinoscope caliber, digital display calliper, A/B ultrasound machine (Allergan Humphery,853).Methods1.4-5 weeks old cat(1) exam refractive state.(2) exam axial length with A -mode ultrasound. (3 ) suture the eyelid of experimental group cat.2. 12 -13 weeks old cat (8 weeks after eyelid suture) (1 ) remove the suture , exam the refractive state and axial length of experimental group and control group.(2) suture the eyelid of experimental group again.3.18 -19 weeks old cat {14 weeks after eyelid suture)(1) same as (1) in 2.(2) remove the eye balls of all the cats, exam the pathological change of retina and sclera under light microscope.Results1. Change in refractive state and axial length ( AL) All the young cats (4-5 weeks old ) are hypermetropia, the mean refractive state is +2.52 0.40D, the mean AL is 11.98 0. 33mm,no difference in both eyes. At 12 -13 weeks ,the both eyes of control group and the controlled eye in experimental group were emme-tropia, the refractive state is +0.51 0. 34D, the mean AL is 15.14 0.22mm, At 18-19 weeks ,the eyes were mild myopia, the refractive state is - 0. 43 0. 33D, AL is 16. 79 0. 23mm. The sutured eyes of experimental group were myopia, 14 weeks after eyelid suture, the refractive state is -2. 45 0. 33D, AL is 18. 95 0. 27mm, the difference was significant ( P <0. 001) .2. The pathological change in the posterior pole of cat ball. At 14 weeks after form deprivation, the posterior sclera was thinner ,the sclera collagen fiber arrangement was disturbed. The number of nucleus of retina nuclear layer is less , the size of cell body of ganglion cell is smaller , cellular Nissl body is less or disappeared . The cone and rod were edema, cellular structure unclear.DiscussionTo make the myopia models in young animal by form deprivation was observed first in 1977 by neurophysiologist Wiesel and Raviola. People try to explain the mechanism of genesis and development of myopia. In this study , the myopia was made on young cat by form deprivation, the refractive state, axial length and histological change in posterior eyeball were examed to investigate the mechanism of pathological myopia.Cats are vertebrate animal with binocular vision , similar to human ,and so is the development stage of cat eye . So the cats were chose as experimental animal in this study. This group young cats are hypermetropia at 4 - 5 weeks old , while becoming emmetropia as developing. The sutured eyes in experiment group were myopia obviously. The difference with control group was significant ( P < 0.001) ,andincreased with the time of form deprivation. At 4 to 12 week , the AL increased most rapidly, at 12 to 19 week, the increase in AL slowed down. In experiment group , after form deprivation , the AL increased rapidly and result in obvious axial myopia.In our study , at 14 weeks after form deprivation , the solera was thinner , arrangement of sclera collagen fiber disturbed . The change in myopic sclera was thought due to the over...
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