Objective To analyze the effects of tyrosinase on choroidal and retinal thickness and blood flow changes in guinea pigs,and to explore the role of tyrosinase in the development and progression of myopia.Methods A total of 30 three-week-old male tri-colored guinea pigs and 10 albino guinea pigs were selected and divided into four groups:control group(tri-colored hyperopic guinea pigs,with no intervention),albino group(albino myopic guinea pigs,with no inter-vention),myopia group(tri-colored myopic guinea pigs,with no intervention),and injection group[tri-colored hyperopic guinea pigs,injected with tyrosinase inhibitor(6 250 μg·L-1),100 μL per day].The experiment lasted for 4 weeks.The refractive status and axial length(AL)of the guinea pigs in each group were measured,along with ocular biometric param-eters related to axial length[anterior chamber depth,aqueous humor depth(AQD),central corneal thickness,lens diame-ter,vitreous chamber depth(VCD)].Optical coherence tomography was used to measure the retinal thickness,choroidal thickness(ChT),and choroidal blood perfusion(ChBP)in different regions of the guinea pigs.The tyrosinase activity in the vitreous and retina of guinea pigs in each group was measured.The expression levels of neurotransmitters in the vitre-ous and retina of guinea pigs in each group were detected.Results The differences in refractive status between the albi-no group and the control group at 0,2,and 4 weeks of the experiment were statistically significant(F=8.972,P＜0.05).At the 4th week of the experiment,the refractive status of the injection group was lower than that of the control group,and the AL was greater than that of the control group,with statistically significant differences(both P＜0.05).Further analysis of AL-related biometric parameters revealed that only AQD and VCD were associated with the changes in AL of guinea pigs in each group.At the 0th week of the experiment,the average retinal thickness of the control group was greater than that of the albino group,with a statistically significant difference(t=-9.007,P＜0.000 1).Moreover,the differences in reti-nal thickness in the outer retina across different directions and time points were statistically significant(all P＜0.05).The differences in retinal thickness between the control and albino groups were mainly concentrated in the outer retina.The ChT of the albino group was less than that of the control group,with a significant difference between groups(F=4.809,P=0.030).The ChBP of the control group was significantly higher than that of the albino group at 0,2,and 4 weeks of the experiment(all P＜0.05).At the 4th week of the experiment,the tyrosinase activity in the vitreous of the injection,albi-no,and myopia groups was lower than that of the control group,with statistically significant differences(all P＜0.05).The differences in neurotransmitters between the albino and control groups were mainly concentrated in the vitreous.In the retina,the ornithine level in the myopia group was higher than that in the albino and control groups,and the tryptophan levels in the myopia and control groups were higher than that in the albino group,with statistically significant differences(all P＜0.05).Conclusion Tyrosinase plays a crucial role in the development of myopia,regulating the development of refractive status by influencing the physiological properties of the retina and choroid.

Objective To analyze the effects of tyrosinase on choroidal and retinal thickness and blood flow changes in guinea pigs,and to explore the role of tyrosinase in the development and progression of myopia.Methods A total of 30 three-week-old male tri-colored guinea pigs and 10 albino guinea pigs were selected and divided into four groups:control group(tri-colored hyperopic guinea pigs,with no intervention),albino group(albino myopic guinea pigs,with no inter-vention),myopia group(tri-colored myopic guinea pigs,with no intervention),and injection group[tri-colored hyperopic guinea pigs,injected with tyrosinase inhibitor(6 250 μg·L-1),100 μL per day].The experiment lasted for 4 weeks.The refractive status and axial length(AL)of the guinea pigs in each group were measured,along with ocular biometric param-eters related to axial length[anterior chamber depth,aqueous humor depth(AQD),central corneal thickness,lens diame-ter,vitreous chamber depth(VCD)].Optical coherence tomography was used to measure the retinal thickness,choroidal thickness(ChT),and choroidal blood perfusion(ChBP)in different regions of the guinea pigs.The tyrosinase activity in the vitreous and retina of guinea pigs in each group was measured.The expression levels of neurotransmitters in the vitre-ous and retina of guinea pigs in each group were detected.Results The differences in refractive status between the albi-no group and the control group at 0,2,and 4 weeks of the experiment were statistically significant(F=8.972,P＜0.05).At the 4th week of the experiment,the refractive status of the injection group was lower than that of the control group,and the AL was greater than that of the control group,with statistically significant differences(both P＜0.05).Further analysis of AL-related biometric parameters revealed that only AQD and VCD were associated with the changes in AL of guinea pigs in each group.At the 0th week of the experiment,the average retinal thickness of the control group was greater than that of the albino group,with a statistically significant difference(t=-9.007,P＜0.000 1).Moreover,the differences in reti-nal thickness in the outer retina across different directions and time points were statistically significant(all P＜0.05).The differences in retinal thickness between the control and albino groups were mainly concentrated in the outer retina.The ChT of the albino group was less than that of the control group,with a significant difference between groups(F=4.809,P=0.030).The ChBP of the control group was significantly higher than that of the albino group at 0,2,and 4 weeks of the experiment(all P＜0.05).At the 4th week of the experiment,the tyrosinase activity in the vitreous of the injection,albi-no,and myopia groups was lower than that of the control group,with statistically significant differences(all P＜0.05).The differences in neurotransmitters between the albino and control groups were mainly concentrated in the vitreous.In the retina,the ornithine level in the myopia group was higher than that in the albino and control groups,and the tryptophan levels in the myopia and control groups were higher than that in the albino group,with statistically significant differences(all P＜0.05).Conclusion Tyrosinase plays a crucial role in the development of myopia,regulating the development of refractive status by influencing the physiological properties of the retina and choroid.

Retinal metabolism includes material metabolism and energetic metabolism.Retina is one of the most energy-consuming nerve tissue in human body and mainly relies on glycolysis for energy production, which is similar to very fast-growing tumor tissue.This process is known as Warburg effect.Warburg effect is of great significance, which is demonstrated that glucose is metabolized via glycolysis in a more rapid approach in comparison with oxidative phosphorylation pathway.In addition, glucose also supplies neoplastic tissue with carbon source or metabolic intermediates due to biosynthesis.The produced energy of retina is a summation of different retinal cells and tissue, such as photoreceptors, retinal pigment epithelium (RPE), Müller cells and retinal capillary endothelial cells etc.To understand the underlying mechanism contributing to Warburg effect and provide insight into metabolic coupling between neuron and glia is of important significance.Since key glycolysis enzymes (HK2, PFKFB3 and PKM2) take a pivotal role in controlling retinal cell proliferation and neovascularization, bioenergetic strategy targeting these enzymes suggests new idea in the treatment of retinal diseases where energy failure is part of the pathogenesis.Investigating underlying mechanism of retinal energy metabolism can provide new ideas for the treatment of age-related macular degeneration (AMD) and other diseases related to disordered retinal energy metabolism.The Warburg effect of retinal energetic metabolism and its regulatory mechanism were reviewed in this article.

Objective To evaluate the changes of the waveform of the photopic negative response in flash-electroretinogram, visual acuity and central retinal thickness in the treatment of intravitreal injections of bevacizumub. Design Retrospective self-comparative case series. Partidpants 8 subjects (9 eyes) with exudative age-related macular degeneration and 3 subjects (3eyes) with proliferative diabetic retinopathy. Method Evaluation protocol included examinations of the Early Treatment Diabetic Retinopathy study visual acu-ity, visual field, intraocular pressure, fundus fluorescein angiography, optical coherence tomography and flash-electroretinogram. Intravit-real injections of bevacizumab, 1.25 mg (0.05ml), were given under an operating microscope and aseptic conditions. All the subjects were followed-up one month later. Main outcome Measure The amplitudes of PhNR, visual acuity and central retinal thickness. Re-sult At 1 months, the mean amplitudes of PhNR and mean visual acuity in all cases had no obvious change (n=12, P>0.05).The central retinal thickness reduced obviously (n=12, P<0.05), but it was neither significantly correlated with PhNR (r=0.294, P=0.145) nor with visual acuity(r=-0.358, P=0.073). Conclusion The single intravitreal injection of bevacizumab is showed promising in absorption of in-traretinal edema and subretinal fluid in patients with exudative age-related macular degeneration and proliferative diabetic retinopathy, but the changes of visual function (including PhNR) might need further investigation. (Ophthalmol CHN, 2009, 18: 243-246)