Diffuse Low Dose532nm Laser Eye Injury

Objective:To establish effective, controllable, simple and good repeatable animal modelof diffuse low dose532nm laser eye injury. Observe the biological effects, thedose-effect relationship, and investigate the possible molecular mechanism.Methods:Using532nm laser and a homemade apparatus, experimental animal wasdivided into immediately after laser damage,1D,3D,5D,7d and14d groups. Usefundus photography, FFA and Electroretinogram， HE, electron microscopyexamination. Apoptosis were observed by TUNEL. Use immunohistochemistryand real-time quantitative RT-PCR to observe the mRNA expression of theneurotrophic factor receptor TrkA, TrkB, TrkC and P75NTR after laser exposure.Result:1. The fundus photography and fundus fluorescein angiography showed noabnormality after the laser irradiation in this animal model.2. Electroretinogram show that along with the increase of exposure time,0.01rod response of b wave decreased significantly (P<0.05);0.3max response a, bwave decreased (P<0.05); OPS showed no obvious change (P>0.05)，while0.3cone response a, b wave were obviously reduce (P<0.05).3. HE showed that the thickness of the control group ONL has no obviouschange (P>0.05)，while the thickness of each experimental group ONL becomesthinner (P<0.05).4. Electron microscopy showed the outer segment disc membrane structuredisorder, fragmentation and vacuolization. The nuclei arranged in disorder, nuclearshrinkage, dissolution, vacuolar degeneration, apoptosis bodies appeared.5. TUNEL positive cells staining cells appeared in the outer nuclear layer oflaser irradiation of1d;3d,5d,7d and14d. The apoptosis index gets upward. There was significant difference compared with the normal control group (P <0.05), sobetween each of the two groups (P <0.05).6. TrkA, TrkB, TrkC and P75NTR all expressed in control group. Theexpression of TrkA and TrkB was no significant differences in every layer of retinaafter laser injury，while the expression of TrkC and P75NTR was significantlyincreased, especially in the ganglion cell layer, the inner segments ofphotoreceptors and retinal pigment epithelial. Real-time quantitative RT-PCRshowed retinal P75NTR expression was significantly increased after laser injury.The expression of TrkA, TrkB in the retina was no significant difference in eachtime point while the expression of TrkC continued to increase with the irradiationtime prolonged.Conclusion:1. This study establish an effective, controllable, simple and good repeatableanimal model of diffuse low dose532nm laser eye injury.2. Diffuse532nm laser irradiation at low power density and low energycontinuous for2weeks, with the frequency of one hour each time, two times a day,can not cause visible damage in the fundus.3. Prompt diagnosis of laser blinding weapons injury and estimation ofprognosis, electroretinogram examination should be listed as an importantexamination.4. As the exposure time prolonged, the retinal photoreceptor cell layerthinning was aggravated, apoptosis is the mechanism of retinal light damage modelof photoreceptor cell death, and the outer nuclear layer of retina cell apoptosis isthe most obvious.5. P75NTR plays a promoting role in out nuclear layer’s apoptosis. TrkC asan important endogenous neurotrophic factor receptor antagonist P75NTR,irradiated with laser retinal damage process play a role in photoreceptor apoptosis,protecting the retinal morphology and structure.