Naoko Yonemura

Effect of infusion air pressure on visual field defects after macular hole surgery.

PURPOSE A defect in the visual field is one of the serious complications of macular hole surgery. We investigated the relationship between the occurrence of visual field defect and the location of infusion cannula and air pressure during fluid-air exchange. METHODS We studied 100 eyes from 90 patients with macular holes. All patients underwent preoperative and postoperative visual field testing. Vitreous surgery was performed in a standard three-port fashion, with surgically induced posterior vitreous detachment, fluid-air exchange, and sulfur hexafluoride gas injection. We analyzed differences in surgical methods in three groups. In group A, the infusion cannula was placed inferotemporally, and the air pressure was set at 50 mm Hg. In group B, the infusion cannula was placed inferonasally, and the air pressure was set at 50 mm Hg. In group C, the infusion cannula was placed inferotemporally, and the air pressure was set at 30 mm Hg. RESULTS Eighteen eyes (18%) showed visual field defects after vitrectomy. The defect was always located contralateral to the infusion cannula. There was no statistically significant difference in the incidence of visual field defects in groups A and B. Decreased air pressure reduced the occurrence of visual field defects significantly (24% in group A versus 4% in group C, P = .011). CONCLUSIONS The location of the visual field defect correlated with the location of the infusion cannula. The incidence of this visual field defect was influenced strongly by the infusion air pressure. The visual field defect may be caused by the mechanical damage of air infusion.

Neuroprotective effects of interleukin-6 on NMDA-induced rat retinal damage.

This study shows that interleukin-6 (IL-6) combined with soluble interleukin-6 receptors (sIL-6R) modulates N-methyl-D-aspartate (NMDA)-induced retinal damage. Eyes pretreated with a combined injection of IL-6 and sIL-6R had NMDA administered into the vitreous cavity. Morphometric analysis and retrograde labeling analysis found that pretreatment with either IL-6 or sIL-6R alone did not bring about any neuroprotective effect. However, pretreatment with a combined administration of IL-6 and sIL-6R induced a significant neuroprotective effect against NMDA-induced retinal damage. Apoptotic changes in the retina were assessed by the TUNEL method. The results indicated that pretreatment with IL-6 combined with sIL-6R prevents NMDA-induced apoptosis. Western blotting studies demonstrated upregulation of gp130 expression in the NMDA-injected retina. Present studies suggest that IL-6 combined with sIL-6R provides a neuroprotective effect on NMDA-induced retinal damage.

Fundus changes corresponding to Visual field defects after vitrectomy for macular hole

OBJECTIVE Visual field defects are one of the complications of macular hole surgery, and mechanical retinal damage induced by infusion air is a proposed causative factor of this complication. In this study, we examined the fundus to see whether the changes observed corresponded to postoperative visual field defects. DESIGN Observational case series. PARTICIPANTS Seventeen eyes of 17 patients who had postoperative visual field defects after vitrectomy for idiopathic macular hole were examined. METHODS The fundus was examined by ophthalmoscopy and by fluorescein and indocyanine green angiography. MAIN OUTCOME MEASURES Fundus changes corresponding to postoperative visual field defects. RESULTS In eight eyes, detectable fundus changes were observed, including regional mottling and degeneration of the retinal pigment epithelium, filling delay of the choroidal circulation, subretinal fibrosis, and epiretinal membrane formation. These findings corresponded exactly to the visual field defects observed. Although the visual field defects had been detected shortly after surgery, fundus changes were detected, on average, more than 8 months after surgery. CONCLUSIONS Fundus changes become apparent after surgery, and they are progressive. Therefore, it is important to examine eyes with visual field defects for a follow-up period of several years.

Species Differences of Serum Albumins: III. Analysis of Structural Characteristics and Ligand Binding Properties During N-B Transitions

AbstractPurpose. The aim of this study was to investigate the characteristics of the structural transitions and changes in ligand binding properties of different albumins during the pH-dependent structural transition, often referred to as the N-B transition. Methods. Structural transitions were evaluated by means of spectrometry, differential scanning calorimetry and chemical modification. In addition, ligand binding properties were investigated using typical site-specific bound drugs (warfarin, phenylbutazone, ibuprofen and diazepam). Results. Conformational changes, including N-B transition, clearly occurred in albumins from all species used in this study. The conformational stabilities of all the albumins were clearly lost in the weakly alkaline pH range. This was probably the result of the destruction of salt bridges between domain I and domain III in the albumin molecule. In addition, the profiles of the ANS-induced fluorescence were different and could be classified into two patterns, suggesting that hydrophobic pockets in the albumin molecules were different for the different species. The data suggest that the amino acid residues responsible for the transitions were some of the His residues located in domain I. Further, the ligand binding properties of the albumins were slightly different but statistically significant. Conclusions. The overall mechanisms of the N-B transition may be similar for all the albumins, but its impact is considerably different among the species in terms of both structural characteristics and ligand binding properties. Furthermore, the transitions appear to be multi-step transitions.

Plasmin-assisted vitrectomy for management of proliferative membrane in proliferative diabetic retinopathy: a pilot study.

Purpose: To demonstrate the feasibility of autologous plasmin for treatment of proliferative diabetic retinopathy. Methods: The study examined prospectively six patients with bilateral proliferative diabetic retinopathy. Comparisons of the surgical time and the incidence of retinal tears were made between the eyes treated with autologous plasmin and their respective opposite eyes, which were treated without plasmin. Results: All eyes treated with autologous plasmin required significantly less surgical time (68 versus 89 minutes, P = 0.04, paired t-test). In the plasmin group, no additional surgical procedures for removing the proliferative membrane were needed, including membrane delamination or segmentation. Moreover, with plasmin pretreatment, there were no retinal tears, which was in contrast to the control group, where three eyes with retinal tears were observed. There was no significant difference found between the two groups for final visual outcomes. Conclusion: Autologous plasmin may be beneficial in the surgical management of proliferative diabetic retinopathy.

New infusion cannula for prevention of retinal damage by infusion air during vitrectomy.

Purpose Postoperative visual field defects are sometimes found after macular hole surgery. We have previously shown that damage to the retina by air infusion from an infusion cannula is a causative factor. To minimize such damage, we modified the infusion cannula and examined its effects experimentally. Methods An infusion cannula with a closed tip and openings on four sides was created. Experimentally, a vitrectomy was performed in rabbit eyes using this new infusion cannula or a conventional cannula. After fluid–air exchange at an air pressure of 40 mmHg, eyes were removed and processed for histologic examination. The areas of the retinal damage caused by air infusion were evaluated. Results The area of retinal damage created by the new cannula was reduced significantly when compared with damage from conventional cannula use. Conclusion This new cannula, designed for the purpose of scattering the air infusion, can reduce retinal damage, which leads to less frequent postoperative visual field defects.

Retinal tear located beneath the detached internal limiting membrane associated with ruptured macroaneurysm.

BACKGROUND Rupture of retinal arterial macroaneurysm has a variety of fundus features. We report a case of ruptured retinal arterial macroaneurysm appearing concomitantly with a retinal tear located beneath the detached internal limiting membrane (ILM) that was apparent during vitrectomy. METHODS Vitrectomy with ILM peeling was performed on a 50-year-old man for sub-ILM hemorrhage and subretinal hemorrhage caused by ruptured macroaneurysm. RESULTS After ILM peeling, a retinal tear was found within the detached ILM. The sub-retinal hemorrhage was aspirated from the retinal tear. The retina was finally reattached. CONCLUSIONS Extensive sub-ILM hemorrhage may cause retinal tear. Careful intraoperative examination and treatment are needed.