Intraocular use of hydrogel tissue adhesive in rabbit eyes.

PURPOSE: To evaluate the safety and efficacy of newly developed hydrogel glue to treat rhegmatogenous retinal detachments in in vitro and in vivo studies. METHODS: In the in vitro study, the solid hydrogel glue was soaked in a balanced salt solution (BSS). The pH was measured periodically, and the dissolution time was recorded. In the in vivo study in six albino rabbits, 0.1 ml of hydrogel glue was injected into the right vitreous cavity, and 0.1 ml BSS was injected into the left vitreous, as the control. Clinical, electroretinography (ERG) and histological examinations were performed. Retinal detachment with a retinal hole was created in 12 albino rabbits after vitrectomy. After fluid-air exchange, the hydrogel glue was applied to the hole in nine rabbits; three other rabbits were used as controls. Clinical and histological examinations were performed. RESULTS: The pH ranged from 6.65 to 8.14. The glue remained solid in BSS for 7 weeks. The glue injection did not induce inflammation. There was no significant difference between the study and control eyes in the ERG amplitude or the implicit times of the a and b waves. No significant histological abnormality was detected. The retina was reattached with glue in three of nine eyes. The histological examination showed glue under the retina. CONCLUSIONS: Hydrogel glue, which seemed to be minimally toxic to the eye, can be used to patch retinal breaks. However, methods to mix a small amount of each solution completely and a more effective intraocular delivery system for the glue are needed.

[Evaluation of cases of polypoidal choroidal vasculopathy showing classic choroidal neovascularization in their natural course].

BACKGROUND: Some cases of polypoidal choroidal vasculopathy (PCV) in their natural course develop into classic choroidal neovascularization(CNV) as shown by fluorescein angiography (FA) findings. SUBJECTS AND METHOD: We evaluated 8 eyes of 8 PCV patients showing classic CNV by FA findings, using indocyanine green angiography (IA) and optical coherence tomography(OCT). RESULT: All patients showed subretinal grayish exudates, which were considered fibrinous. Five cases were recognized as true subretinal CNV according to IA and OCT findings. The other 3 patients showed polypoidal dilatation with vascular networks by IA, and a moderately reflective mass considered fibrinous over the polypoidal elevation of retinal pigment epithelium (RPE) by OCT. CONCLUSION: Both true CNV and PCV with fibrin are present in PCV patients showing classic CNV. It requires care to determine proper treatment.

[Optical coherence tomographic findings of the retinal pigment epithelium tear in macular area preserving good visual acuity].

PURPOSE: It has been reported that the visual outcome of retinal pigment epithelial tear (RPE tear) in the fovea is worse than that of RPE tear sparing the fovea. We report optical coherence tomography (OCT) findings of 3 cases with RPE tear in the fovea who preserved good visual acuity. PATIENTS: All patients had serous retinal pigment epithelial detachment involving the macula. The RPE was torn and rolled RPE was observed in the fovea. In OCT findings, a fovea was observed on the RPE flap, and visual acuity was preserved after RPE tear repair. CONCLUSION: We considered that preservation of good visual acuity was due to the presence of a fovea on the RPE flap. We could precisely analyze the location of the fovea and RPE tear using OCT.

Quantitative evaluation of ischemia-reperfusion injury by optical coherence tomography in the rat retina.

PURPOSE: To determine whether optical coherence tomography (OCT) can detect early retinal changes after ischemia-reperfusion injury in rats. METHODS: The intraocular pressure (IOP) was elevated to induce retinal ischemia in brown Norway rats. After 90 min of ischemia, the IOP was reduced, and after reperfusion of 1, 2, 4, or 7 days, OCT was performed. After the OCT examination, the eyes were enucleated and histological sections were made. RESULTS: The OCT-determined mean retinal thickness was 168 +/- 16.9 microm in the untreated control group, and 177 +/- 2.16, 170 +/- 7.55, 159 +/- 5.34, and 140 +/- 5.56 microm on days 1, 2, 4, and 7, respectively, in the ischemia-reperfusion group. The histologically determined retinal thicknesses correlated with those obtained by tomographic images, but the histologic thicknesses were 9.5% to 18.5% thinner than those obtained by OCT. Fixation and dehydration of the histological specimens most likely caused tissue shrinkage. CONCLUSIONS: OCT can detect retinal changes quantitatively after ischemia-reperfusion injury, and the retinal thicknesses obtained from OCT images are probably a better measure of the true retinal thickness than those measured on histological sections.

Hydrogel tissue adhesive for sealing corneal incisions.

The purpose of the study was to assess the efficacy of a newly developed hydrogel tissue adhesive for sealing corneal incisions in ex vivo rabbit eyes. Simple through-and-through central linear corneal incisions measuring 1-5 mm were created in enucleated rabbit eyes. As controls, the leaking pressures were measured immediately after the incisions had been made. Afterwards, the incisions were sealed with hydrogel adhesive in group 1 and with a single 10-0 nylon suture in group 2. The leaking pressure of each incision was measured after the wounds had been sealed in both groups. The leaking pressures of the controls and the sealed incisions were compared for statistical significance using the Wilcoxon signed rank test. The difference between the leaking pressures before and after sealing the incisions in groups 1 and 2 were compared using the Mann-Whitney rank sum test. The leaking pressures were significantly higher after sealing in both groups 1 and 2 compared to the controls for all incision sizes. The differences in the leaking pressures before and after adhesive application were higher than before and after suturing in all incision sizes. The differences were all statistically significant except for the 1-mm incisions. We conclude that the hydrogel glue has the potential to be used for sealing corneal incisions measuring up to 5 mm.