The Effect of Amniotic Membrane on Adhesion after Strabismus Surgery in Rabbits

PURPOSE: Amniotic membrane has been used as an effective graft intraabdominally to prevent postoperative adhesion formation. We evaluated whether amniotic membrane would be effective in preventing adhesion after strabismus surgery in the rabbits. METHODS: After bilateral recessions of superior rectus(SR) were performed on 10 rabbits, iatrogenic bleeding was induced by scratching the surface of SR with a blade. For the experimental group, the SR was enveloped with folded, epithelial side-out, human amniotic membrane in the right eyes of all rabbits, while the left SR was left in each rabbit to act as a control. At two weeks postoperatively, both eyes were enucleated after being sacrificed. Masson's trichrome staining was performed and the degree of fibrous proliferation and inflammation were evaluated and scored grade 0 to 3. RESULTS: The degree of fibrosis was observed to be lower in the experimental group than in the control group (1.67:2.33). However, there was no statistical significance(p>0.05). Also, there was no statistical significance in the degree of inflammation between experimental and control groups(p>0.05). CONCLUSIONS: The amniotic membrane showed no significant effect of prevention of adhesion after strabismus surgery in the rabbit model.

Delayed Absorption of Subretinal Fluid after Scleral Buckling Procedure for Rhegmatogenous Retinal Detachment

Delayed absorption of subretinal fluid[SRF]occurs not so infrequently after scleral buckling for rhegmatogenous retinal detachment and needs to be differenciated from the condition caused by incomplete closure of retinal break or by proliferative vitreoretinopathy.The purpose of this study was to identify perioperative factors associated with delayed absorption of SRF after scleral buckling.Eighty-four consecutive cases of rhegmatogenous retinal detachment had undergone scleral buckling and been followed for more than 3 months.The duration was shorter than 7 days in early reattachment group[group A, n=65]and the duration was the same as 7 days or longer in delayed absorption group[group B, n=19].Perioperative demographic and ocular factors were analysed.Old age, inferior retinal detachment, operculated tear and proliferative vitreoretinopathy were more prevalent in group B than in group A[p<0.05]. Subretinal gliotic band, demarcation line and subretinal precipitate were detected in group B.Our results suggest that the hypofunction of retinal pigment epithelium and the vitreous traction may play a role in delayed absorption of SRF.

Effect of Oxygen on Photoreceptor Degeneration in Retinal Degeneration Mice

There is still no effective treatment for retinal degenerative diseases, in which the loss of photoreceptor cells causes visual loss and eventually blindness. Despite the current studies show that intraocular injection of basic fibrobalst growth factor rescues damaged and dystrophic rat photoreceptor in transgenic animal, there is a few evidence that endogenous neurotrophic factor promotes photorecptor cell survival in retina. In the present study, retinal degeneration (rd)neonate mice were exposed to hyperoixa for 5 days, and then were returned to room air, which was presumed to cause relative hypoxia of nonperfused retina, producing a neovascular response. Using this model, we investigated the effect of relative hypoxia on degenerative process in rd mice. As a control, rd neonate mice were remained at room air from birth. At the postnatal 10, 12, 14, 16, 18 and 21 days, the ratio of total retinal thickness and outer nuclear layer (ONL)thickness, and neovascularization of experimental right eyes were compared with those of control. Extent of vascularization of experimental left eyes was compared with that of left eyes in control group. In rd mice, extraretinal neovascularization was observed in 62%of 93 eyes of the experimental group exposed to hyperoxia. Extent of vascularization in experimental group was smaller than that of in control. There was an oxygen-induced modulation of rates of death in experimental group, where-as the death of photoreceptor progressed in control group. In experimental group, the ratio of total retinal thickness and ONL thickness was higher than that of in control group at 18 and 21 days of age. These results suggest that the relative hypoxia in the rd mice may have rescue effect on photoreceptor in rd mice.

The Clinical Results of Limbal Conjunctival Autograft Transplantation with Intraoperative Mitomycin C Application for Recurrent Pterygia

The recurrence is common problem to treat pterygium. Many surgical procedures were adopted to reduce the recurrence rate. We evaluated the surgical results of limbal conjunctival autograft transplantation (LCAT) accompanying application of 0.02% mitomycin C intraoperatively in 10 patients (10 eyes) who had a recurrent pterygium. There were 7 eyes with first recurrence and 3eyes with second recurrence. Mean age of the patients was 57.4 years, and mean follow-up period was 9.3 months. After a pterygium was excised, a sponge soaked in a solution of mitomycin C 0.02% was applied to the sclera at the site of the surgical bed for 2 minutes, then superior temporal limbal tissue was taken with conjunctival flap and transplanted to the excised area. None of all cases recurred for follow-up period and donor conjunctival site was well reepithelialized. In concluion, LCAT accompanying application of 0.02% mitomycin C intraoperatively was effective and safe method for recurrent pterygium.