Résumé
·AIM:To study the pathogenesis of transient intraocular pressure ( IOP ) after laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser.· METHODS: Totally 42 healthy rabbits ( 84 eyes ) provided by the Animal Experimental Center of our hospital were selected, including 18 female rabbits, 24 male rabbits, average weight 2. 24±0. 31kg, and they were randomly divided into 6 groups, 7 rats in each group (14 eyes) . We observed the change of intraocular pressure after laser iridectomy surgery at 20min, 2, 6, 18, 24h and the nitric oxide ( NO ) , malondialdehyde ( MDA ) , superoxide dismutase ( SOD) , 6-keto-prostaglandin ( 6-keto-PGF1α) and nitric oxide synthase ( NOS) content in aqueous.· RESULTS: There was no significant difference in intraocular pressure, NO, NOS, SOD, MAD and 6-keto-PGF1α before operation ( P > 0. 05 ). The intraocular pressure increased after operation, and the difference was statistically significant (P<0. 05) at 20min, 2 and 6h after operation, and decreased at 18h after operation, 24h after operation (P>0. 05). The levels of NO, NOS and SOD in the aqueous humor of the two groups decreased 20min, 2 and 6h after the operation (P<0. 05), while increased after 6h, increased more at 18 and 24h. The difference with control group was no more significant (P>0. 05). The levels of MDA and 6-keto-prostaglandin in the aqueous humor increased after the operation, and the difference was statistically significant at 20min, 2 and 6h after operation (P<0. 05), while decreased at 18 and 24h and the difference with control group was not significant ( P>0. 05).· CONCLUSION: The increase of transient intraocular pressure after laser iridectomy may relate to the increase of malondialdehyde, 6-keto-prostaglandin content and the decrease of superoxide dismutase and nitric oxide in the aqueous humor after operation.
Résumé
We compared the effects of diode laser (DL) irradiation of the iris with those of argon laser (AL). Histopathologic examination of laser-induced lesion, measurements of aqueous flare and prostaglandin (PG) E2 were performed. DL was applied in one eye of each animal and the fellow eye received ALwith the same parameters in 49 pigmented rabbits. At 1 hour after irradiation, the mean flare count was higher in the DL-treated eyes than in AL-treated eyes(p0.05). On histopathologic examinations, iris defect by DL was wider and shallower than that by AL. The extent of coagulation of the iris tissue was more extensive in the DL-irradiated iris. Our results suggest that the DL irradiation may be more harmful to the blood-aqueous barrier and iris tissue than AL. Further development of the laser equipment or the treatment regimen for diode laser iridotomy may be necessary.
Sujets)
Animaux , Lapins , Humeur aqueuse , Argon , Barrière hématoaqueuse , Pression intraoculaire , Iris , Lasers à semiconducteurRésumé
Recently iridectomy using an argon or Nd-YAG laser to treat narrow angle glaucoma has become popular, and is now the procedure of choice over the standard surgical technique. However, the shock wave of the Nd-YAG laser causes hemorrhage in almost all cases and the high energy level of the Nd-YAG laser, which is required for iridectomy, causes injury to the lens and cornea. Furthermore, there is a tendency toward closure of the iridectomy site after argon laser application. We performed iridectomies by a combined application of argon and Nd-YAG lasers in pigmented rabbits to improve iris bleeding, iridectomy patency, and lens and corneal damage. The iridectomy patency and the lens and corneal damage were examined with a scanning electron microscope. The rabbits that underwent laser iridectomies with only the Nd-YAG laser were used as a control group. Based on the results, it can be concluded that laser iridectomy by a combined application of argon and Nd-YAG lasers results in a lower rate of bleeding, a higher rate of patency, and less damage to the lens and cornea as compared with iridectomy performed by Nd-YAG laser only.