Toxicity Of Manganese Ion Eye Drops To Ocular Surface And Anterior Segment Of Rabbits

PurposeTraumatic optic neuropathy is an important cause of permanent visual impairment in clinical. But at present clinical routine inspection can not confirm and assess the damage location and degree of traumatic optic neuropathy. It is recognized that MRI is the principal method to display optic nerve and organization after eyeball. MRI has been given more attention and widely used in the field of visual imaging since its introduction. However, due to the complex structure of the optic nerve and the influence of its surrounding structures, MRI examination of the optic nerve has great limitations.Similarly to Ca2+, Mn2+ can replace to observe the flow and relation of neuron, which has initial progress. The research in MEMRI examination of the optic nerve is followed increasely.In recent years, the method which observe visual pathway by use of MEMRI is discovered. An intravitreal injection of Mn2+ for MEMRI has been researched. Feasibility of the diagnosis and display diseases by topical administration of Mn2+ for MEMRI is being studied. But the toxicity of manganese ion eye drops to ocular surface and anterior segment has not been studied. This experiment has preliminary observation.Materials and Methods1 Experimental animals and groupingA total of 32 adult New Zealand White rabbits used, which were healthy,2-2.5 Kg, male or female, from experimental animal center of Henan province, were excluded eye disease by conventional slit lamp. All the use, breeding and execution of animals follow American Association for Research in Vision and Ophthalmology developed using standard. This research conformed to medical research ethics committee of the First Affiliated Hospital of Zhengzhou University. The rabbits were divided into four groups randomly. A, B and C group as experimental group. D group is the control group. The experimental groups were ramdonly selected as an experimental eyes and control group also determine the physiological saline eye by drawing. The right eyes in each group received different concentration of manganese ion eye drops treatment (1mol/L.0.5mol/L,0.25mol/L. and Omol/L, respectively). The fellow eyes served as internal controls.2 MethodsCorneal fluorescence staining, corneal specular microscope were used to evaluate the changes of epithelium layer, endothelial layer and the thickness of cornea after treatment at different time points (1 hour,2 hours.4 hours,6 hours,12 hours,24 hours.36 hours,2 days,3 days,5 days,7 days,14 days,21 days, and 28 days, respectively). The histological changes of conjunctiva, cornea, trabecular meshwork. and ciliary body were evaluated at 3 days,7 days,14 days,28 days after treatment.3 Statistical analysisUsing SAS 9.13 statistical software to analyze all the data. The prevalence of corneal fluorescence staining comparison of four groups used Frideman. Bonferroni between groups. The prevalence of endothelial layer and the thickness of cornea comparison of four groups used ANOVA of Repeated Measures. The significance level was P<0.05.Results1 The prevalence of eye ocular irritation in rabbits with different concentration of manganese ion eye dropsThe tests of different time points:Group A:6.0,7.0,8.0,8.0,9.0,11.0,8.0,6.0,5.0, 5.0,3.0,2.5,1.0,1.0; Group B:5.0,5.0,5.0,5.0,5.0,5.5,4.0,4.0,2.5,1.5,1.0,1.0,1.0,1.0; Group C:2.0,3.0,2.0,3.0,3.0,2.0,0,1.0,0,1.0,0,0,1.0,0; Group D:2.0,1.0,0,0,1.0,0,1-0,0, 0,1.0,0,0,1.0,0;(0-4 Non-irritant; 5-9 Mild irritant; 10-14 Moderate irritant; 15-20 Severe irritant)Group A had serious eye stimulation reaction, which was the most at 1d; Group B also had eye stimulation reaction, which was not serious.Group C had no eye stimulation reaction.2 The prevalence of Cornea Fluorescein Staining in rabbits with different concentration of manganese ion eye dropsThe tests of different time points:Group A:3.0(2.50,3.50),4.0 (3.50,4.50),4.0 (3.50,4.50),4.0 (3.50,4.50),4.0 (3.75,4.25),5.0 (4.25,4.75),4.0 (3.50,4.50),3.0 (2.50,3.50),2.5 (2.25,2.75),2.0 (1.50,2.50),2.0 (1.50,2.50),1.0 (0.50,2.50),0.5 (0.25,0.75),0 (0,0); Group B:2.0 (1.50,2.50),2.0 (1.50,2.50),2.5 (2.25,2.75),3.0 (2.50,3.50),3.0 (2.50,3.50),3.0 (2.50,3.50),2.5 (2.25,2.75),2.0 (1.75,2.25),1.0 (0.50,1.50),0.5 (0,1.00),0.5 (0.25,0.75),0 (0.25,0.75),0 (0,0),0 (0,0);Group C:1.0(0.75,1.25),1.0(0.50,1.50),1.0(0.50,1.50),1.0(0.50,1.50),1.0(0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),0 (0.25,0.75),1.0(1,1),0.5(0.25,0.75),0.5(0.25,0.75); GroupD:1.0(1.25,1.75),1.0 (1.25,1.75),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),1.0 (0.50,1.50),0.5 (0.50,1.50),1.0 (0.25,0.75),0 (0,0),0.5 (0.25,0.75)At 2h-7d, four groups had statistical significance(p<0.05);at 14d-28d, four groups had no statistical significance(p>0.05).3 The prevalence of corneal endothelial cell density and morphology in rabbits with different concentration of manganese ion eye dropsThe tests of different time points:Group A:(2779.8±171.7)/mm~2, (2696.3±184.9)/mm~2.(2933.5±133.9)/mm~2.(2932.9±135.8)/mm~2,(2 785.8±176.6)/mm~2, (2891.6±204.8)/mm~2.(2883.8±118.4)/mm~2, (2937.6±189.3) /mm~2, (2792.1±257.4)/mm~2. (2781.3±233.9)/mm~2, (2750.1±258.6)/mm~2, (2946.9±166.8)/mm~2, (2904.6± 108.7)/mm~2,(2811.8±109.3)/mm~2; Group B:(2 872.6±198.4)/mm~2, (2840.9±119.7)/mm~2, (2927.3±297.0)/mm~2. (2921.7±225.8) /mm~2, (2772.6±179.9)/mm~2, (2862.7±198.7)/mm~2. (2846.2±124.5)/mm~2, (2 810.6±85.7)/mm~2,(2846.2±124.5)/mm~2.(2749.9±142.3)/mm~2,(2726.2±155.8) /mm~2,(2834.9±186.2)/mm~2,(2894.8±231.5)/mm~2, (2845.2±126.7)/mm~2;Group C:(2696.9±139.8)/mm~2, (2707.6±119.7)/mm~2, (2 919.4±127.9)/mm~2,(2 956.3±133.3)/mm~2, (2802.2±113.3)/mm~2, (2872.9±142.2)/mm~2, (2867.3±126.9) /mm~2, (2870.4±179.5)/mm~2, (2792.6±202.6)/mm~2, (2812.1±169.7)/mm~2, (2771.9±198.7)/mm~2, (2905.3±125.0)/mm~2, (2871.3±93.6)/mm~2. (2832.8±74.9) /mm~2; Group D:(2825.3±205.2)/mm~2,(2779.8±139.4)/mm~2,(2878.7±219.7) /mm~2,(2886.1±174.7)/mm~2,(2783.9±205.9)/mm~2,(2885.6±135.6)/mm~2,(2 781.4±122.6)/mm~2. (2840.9±149.4)/mm~2,(2827.9±250.5)/mm~2,(2783.5±165.9) /mm~2,(2727.6±138.6)/mm~2,(2820.0±189.8)/mm~2, (2836.4±108.9)/mm~2, (2858.7±97.5)/mm~2.Four groups had no statistical significance(p>0.05). It had no obvious change in corneal endothelial cell morphology.4 The prevalence of corneal thickness in rabbits with different concentration of manganese ion eye dropsThe tests of different time points:Group A:(0.329±0.011)mm,(0.328±0.007) mm,(0.333±0.005)mm,(0.333±0.004)mm,(0.398±0.005)mm,(0.403±0.007) mm,(0.380±0.008)mm,(0.381±0.009)mm,(0.345±0.018)mm,(0.330±0.005) mm,(0.332±0.018)mm,(0.321±0.007)mm,(0.319±0.006)mm,(0.317±0.004) mm; Group B:(0.328±0.010)mm,(0.328±0.007)mm,(0.326±0.010)mm, (0.327±0.009)mm,(0.348±0.009)mm,(0.330±0.009)mm,(0.329±0.009)mm, (0.325±0.009) mm, (0.322±0.009) mm, (0.322±0.005) mm, (0.322±0.004) mm, (0.325±0.010) mm, (0.318±0.007) mm, (0.318±0.008) mm; Group C: (0.318±0.004) mm, (0.319±0.005) mm, (0.319±0.004) mm, (0.322±0.006) mm, (0.320±0.004) mm, (0.321±0.004) mm, (0.321±0.004) mm, (0.323±0.004) mm, (0.322±0.003) mm, (0.321±0.004) mm, (0.322±0.002) mm, (0.320±0.003) mm, (0.320±0.003) mm, (0.321±0.003) mm; Group D:(0.319±0.004) mm, (0.319±0.005) mm, (0.320±0.004) mm, (0.323±0.006) mm, (0.321±0.004) mm, (0.321±0.004) mm, (0.322±0.004) mm, (0.323±0.004) mm, (0.322±0.003) mm, (0.321±0.003) mm, (0.322±0.002) mm, (0.320±0.002) mm, (0.320±0.002) mm, (0.321±0.002) mm.Corneal thickness increased at early stage in group A and group B(p<0.05). Corneal thickness had no obviously change in group C(p>0.05).5 The prevalence of histopathology of conjunctiva, cornea, trabecular meshwork, ciliary body in rabbits with different concentration of manganese ion eye dropsGroup A at 3d:Tissue edema, hemangiectasis, inflammatory cell infiltration were observed in conjunctiva. Cornea edema, cells of stratum basale bigger; inflammatory cells infiltration in trabecular meshwork and ciliary body.7d:it was similar to 3d, but not serious.14d,28d:it were normal in conjunctiva, cornea, trabecular meshwork and ciliary body. Group B at 3d:Tissue edema, hemangiectasis, inflammatory cell infiltration were observed in conjunctiva, it were normal in cornea, trabecular meshwork and ciliary body.7d,14d,28d:it were normal in conjunctiva, cornea, trabecular meshwork and ciliary body. Group C at 3d,7d,14d and 28d:it were normal in conjunctiva, cornea, trabecular meshwork and ciliary body.ConclusionsThe toxicity of lmol/L and 0.5mol/L manganese ion eye drops to ocular surface and anterior segment is serious and it is unacceptable to human. But the toxicity of 0.25mol/L manganese ion eye drops to ocular surface and anterior segment is not obvious. It is likely to be used to visual pathway tracer.