Purpose  The aim of this study was to investigate the effect of intravitreal injection of D-alpha-aminoadipic acid (D-α-AAA) on refractive state and retinal dopamine in guinea pig deprived eyes.
Methods  Four-week-old pigmented guinea pigs were randomly assigned to five groups: normal control, DL-α-AAA group, deprived group, deprived plus DL-α-AAA group and deprived plus saline group. Form deprivation was induced with translucent eye shields on the right eye, and lasted for fourteen days. 8μg DL-α-AAA was injected into the vitreous chamber of deprived eyes. The corneal radius of curvature, refraction and axial length were measured in all animals. Subsequently, retinal dopamine content was evaluated by the high-performance liquid chromatography with electrochemical detection.
Results  Fourteen days of eye occlusion caused the form-deprived eyes to elongate and become myopic, and the content of dopamine to decrease. Intravitreal injection of D-α-AAA could inhibit the myopic shift (from -4.25±0.95 D to -1.48±0.40 D, P<0.01) and the increase of axial length (from 9.63±0.07 mm to 8.69±0.05 mm, P<0.01) due to goggles occluding. Morever, exogenous D-α-AAA significantly raised the retinal dopamine content in the deprived eyes. Administration of D-α-AAA to the unoccluded animals had no effect on its ocular refraction and retinal dopamine content.
Conclusions  Intravitreal injection of D-α-AAA was effectively able to suppress the development of form deprivation myopia, which may be associated with the change of retinal dopamine in guinea pigs.