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Q. Gao, Q. Liu, P. Ma, X. Zhong, J. Ge; Effects of Directly Intravitreal Dopamine Injections on Development of Lid–Suture Induced Myopia in Rabbits . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1987.
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Purpose: Dopamine stores and release have been shown to be reduced in form deprived myopia (FDM) in a wide range of species, ranging from chickens to primates. FDM can be prevented by treatment with dopamine agonists, such as apomorphine, and, paradoxically, by the dopaminergic neurotoxin, 6–hydroxy dopamine. We have used dopamine itself in an attempt to suppress the development of FDM in a rabbit model. Methods: Fifty–two of seven–day–old neonatal rabbits were divided into 3 groups (A,B, C) and they were monocularly deprived (MD) of pattern vision by suturation of right eyelids after natural eye opening. In group A(n=20), no drug was used, while in group B and C, the rabbits received a series of intravitreal injections of dopamine at dose of 1µg/µL (n=16) or saline vehicle (n=16) with MD, respectively. The right eyes of group C were employed as control. Anterior chamber depth (ACD), lenticular thickness (LT), vitreous chamber length(VCL) and axial length (AL) of each eye were determined by A–scan ultrasonography at the end of the 8– week deprivation period. The ratio VCL/AL was calculated and pathological changes were also observed. Results: VCL,AL and VCL/AL of right eyes in group A and C were 7.9±0.6 mm,15.4±0.6 mm, 0.52±0.03; 7.3±0.5 mm, 15.1±0.7 mm, 0.49±0.02 , respectively. Those of the contralateral control eyes were 7.2±0.8 mm,14.5±0.7 mm,0.48±0.02;6.8±0.4 mm,14.6±0.6 mm,0.46±0.02. VCL, AL and VCL/AL but not ACD and LT of right eyes showed a significant difference in group A and C ( P< 0.001). However, there were not significant difference in group B. Significant reductions in the mean scleral collagen fibril diameters and the number of RPE cells were apparent in right eyes as compared with the contralateral control eyes in all three groups, although the change is smaller in group B. Conclusions: Form deprivation by suturing eyelids is an effective technique to induce myopic shift in the rabbit as a model of myopic development. Longer vitreous chamber, higher VCL/AL, thinner scleral fibrils and decreased RPE cells were found to be associated with myopic growth and dopamine can partially retards the myopic development in sutured eyes
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