Hyperbaric oxygen treatment for experimental intraocular hypertension in rats: An electroretinogram detection

BACKGROUND: Hyperbaric oxygen (HBO) is used for treating glaucoma, and affirmative curative effect has been obtained. HBO can sensitively reflect the obviously heightened b wave of electroretinogram (ERG) of injured tissue. OBJECTIVE: To observe the effect of HBO treatment on retinal function of rats with acute experimental intraocular hypertension with ERG. DESIGN: Randomized controlled experiment. SETTING: Department of Ophthalmology, Third Xiangya Hospital, Central South University; Department of Hyperbaric Oxygen, Xiangya Hospital, Central South University; Department of Anatomy, Xiangya Hospital, Central South University. MATERIALS: Eighteen adult healthy Wistar rats, of either gender, weighing from 150 to 250 g, were provided by the Animal Room of Central South University. Type YLCO. 5/ⅠA baby hyperbaric oxygen chamber, type LMS-2A two-channel physiological recorder, type BG-1 retina exposure system, Jiangwan type Ⅰstereotaxis instrument. METHODS: This experiment was carried out in the Central South University between March and September 2006. Eighteen healthy Wistar rats were made into models of acute experimental intraocular hypertension. Then, they were divided into two groups: model group and HBO treatment group, with 9 in each group. Following 7 days of HBO treatment, the rats in HBO treatment group were placed in Type YLCO. 5/ⅠA baby hyperbaric oxygen chamber, which was pressurized with pure oxygen( volume fraction 0.825±0.025).The treatment pressure was 0.2 MPa. The rats in HBO treatment group daily inhaled HBO for 80 minutes within 7 days; Rats in the model group were untouched. The performance of eyes was observed under the status of intraocular hypertension. ERG was recorded before, during and 7 days after modeling, meanwhile, the recovery rate of b wave from ERG was calculated. Recovery rate of b wave from ERG=(amplitude of b wave 7 days after modeling/ amplitude of b wave before modeling)×100%. MAIN OUTCOME MEASURES: ① Performance of eyes under the status of intraocular hypertension. ② Recovery rate of b wave of ERG. RESULTS: All the 18 rats were involved in the final analysis. ① Performance of eyes under the status of intraocular hypertension.: When intraocular pressure increased until b wave of ERG disappeared, two eyes of rats with corneal opacity, dilated pupils, pale iris and stiffened eyeballs were found. ② Recovery rate of b wave of ERG in the HBO treatment group was significantly higher than that in the model group [(60.04± 19.33)% vs. (41.85±13.20)%,t =3.298,P < 0.01]. CONCLUSION: HBO treatment can obviously promote the recovery of retinal function following acute intraocular hypertension.