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Background
The establishment of chronic ocular hypertension is a basis for the research of glaucoma.Previous laser photocoagulation method to establish ocular hypertension model showed obvious fluctuation of intraocular pressure (IOP) and complications and need repeatedly photocoagulation.Improvement of modeling method is of important significance for glaucoma.
Objective
This study was to establish chronic ocular hypertension rat models by transgoniscope laser photocoagulation to trabecular meshwork and to compare this method with previous translimbal laser photocoagulation.
Methods
Thirty-six 8 to 12-week-old clean grade Fischer344 rats were collected and divided into normal control group, translimbal laser photocoagulation group and transgoniscope laser photocoagulation group, 12 rats for each group.Five hundred and thirty-two nm YAG laser was used to photocoagulate trabecular meshwork translimbally in the right eyes of rats in the translimbal laser photocoagulation group, with the laser power 440-500 mW and spots 40-60, and the photocoagulation was perfored transgoniscopely in the right eyes of rats in the transgoniscope laser photocoagulation group, with the laser power 800-850 mW and spots 100-120.IOP was measured by using Tonolab tonometer in all the rats after modeling.The rats were sacrificed 3 weeks after modeling and retinas were isolated, the Tuj-1 positive retinal ganglion cells (RGCs) were counted by immunofluorescence technology.The use and care of the animals followed the Statement of ARVO.
Results
The successful rate of establishement of models was 75% in the translimbal laser photocoagulation group and 100% in the transgoniscope laser photocoagulation group.The mean IOP was (11.0±1.3), (23.4±12.6) and (25.3±4.9)mmHg, and the peak IOP was (12.3±1.0), (50.5±7.3) and (44.3±12.3)mmHg in the normal control group, transgoniscope laser photocoagulation group and translimbal laser photocoagulation group, respectively, with significant differences among the groups (F=25.496, 80.762, both at P<0.001), and the mean IOP was significantly higher in the transgoniscope laser photocoagulation group and translimbal laser photocoagulation group than that in the normal control group (all at P<0.001), and no significant differences in the mean and peak IOP between transgoniscope laser photocoagulation group and translimbal laser photocoagulation group (P=1.000, P=0.195). The numbers of Tuj-1 positive RGCs in the retinas were (2 048.2±148.5), (645.2±177.1) and (1 223.7±148.6)/mm2 in the normal control group, transgoniscope laser photocoagulation group and translimbal laser photocoagulation group, showing a significant difference among the groups (F=98.767, P<0.001). The number of Tuj-1 positive RGCs was considerably reduced in the transgoniscope laser photocoagulation group and translimbal laser photocoagulation group compared with the normal control group and the number of Tuj-1 postive RGCs was low in the translimbal laser photocoagulation group compared with the transgoniscope laser photocoagulation group (all at P<0.001).
Conclusions
Transgoniscope laser photocoagulation targeting trabecular meshwork can induce chronic ocular hypertension and RGCs losing.However, its pattern is different from translimbal laser photocoagulation.Transgoniscope laser photocoagulation has a higher successful rate of chronic ocular hypertention than that of translimbal laser photocoagulation.