Motoaki Doi

Contribution of nitric oxide-producing cells in normal and diabetic rat retina.

PurposeTo examine the immunohistochemical localization of l-arginine and l-citrulline and determine where and how nitric oxide (NO) is produced in the normal and streptozotocin (STZ)-induced diabetic rat retinas.MethodsNO is produced when l-arginine is changed to l-citrulline by NO synthase (NOS). In normal and STZ-induced diabetic rats, using an immunohistochemical method, we examined the retinal distribution of l-arginine and l-citrulline after intracardiac perfusion. We studied the distribution of NOS after immersed fixation and analyzed the number of neuronal NOS (nNOS)-positive neurons.ResultsWe observed l-arginine localization in the internal limiting membrane (ILM), the ganglion cell layer (GCL), and the inner nuclear layer (INL). l-Arginine immunoreactivity in the diabetic rat retinas was found in the inner plexiform layer (IPL), as well as in the normal retina. l-Citrulline immunoreactivity in the normal and diabetic retinas was observed in the ILM, the GCL, the IPL, and the INL. nNOS staining in the normal and diabetic rat retinas was observed in the GCL, the IPL and the INL. The number of nNOS-positive amacrine cells was less in the diabetic rat retinas.ConclusionNO might be produced in the GCL and amacrine cells, which show immunoreactivity to l-arginine, l-citrulline, and nNOS. In the early stage of diabetic retinopathy in STZ rat retinas, diabetes disturbed the function of the nNOS-positive amacrine cells and reduced NO production via nNOS. Jpn J Ophthalmol 2005;49:363–370

Immunohistochemical Localization of Amino Acids in the Diabetic Retina of Goto-Kakizaki Rats

The Goto-Kakizaki (GK) rat is a spontaneous model of non-insulin-dependent diabetes mellitus without obesity and diabetic retinopathy. We examined the retinal distribution of L-glutamate, gamma aminobutyric acid (GABA), glycine, and L-aspartate as neurotransmitters in the GK rat retina, using an immunohistochemical method with high-affinity antibodies. The retinal structures in the GK rats were the same as the controls. However, in the GK rats, immunoreactivity of L-glutamate and GABA was observed in the Müller and photoreceptor cells in addition to the immunoreactivity in normal rats. There was no change in glycine distribution between GK rats and controls. In the GK rats, L-aspartate accumulated in the inner segment of the photoreceptor cells in addition to the normal distribution. We consider that these immunoreactivity patterns in the GK rat retina might be induced by ischemia associated with diabetes mellitus.

Histopathologic abnormalities in rabbit retina after intravitreous injection of expansive gases and air.

Purpose: To evaluate histopathologic retinal changes in rabbit eyes after injection of pure perfluoropropane (C3F8) gas, pure sulfur hexafluoride (SF6) gas, or air into the vitreous cavity. Methods: Air, C3F8 gas, or SF6 gas (0.4 mL each) were injected into rabbit vitreous cavities. Two, 4, and 6 weeks later, light and electron microscopic examinations were conducted, and the immunohistochemical localization of glutamate in the retina was studied. Noninjected eyes served as controls. Results: At all time points, thinning or disappearance of the outer plexiform layer in the superior retina in eyes that received C3F8 gas was found; the inferior retina was the same as in controls. In eyes that received SF6 gas or air, light and electron microscopy showed that the superior and inferior retina were the same as in controls at all time points. Immunohistochemical examination showed abnormal glutamate distribution of the superior retina in eyes injected with C3F8 gas, SF6 gas, or air. However, glutamate distribution was the same as in controls in the inferior retina in eyes injected with C3F8 gas, SF6 gas, or air. Conclusions: Retinal tamponade using intraocular gases induces histopathologic retinal changes in the superior retina of the rabbit eye, where the gases are in continuous contact with the eye.

Extrusion and fragmentation of hydrogel exoplant 11 years after scleral buckling surgery

MAI or MIRAgel is a hydrogel developed as a scleral buckling material. We identified upper lid masses and a limitation of supraduction in the left eye of a patient who was associated with extrusion and fragmentation of the MIRAgel episcleral exoplant 11 years after scleral buckling surgery. The material could not be removed completely because of fragmentation. Fragmentation and extrusion of MIRAgel may be rare, but periodic long-term follow-up examinations should be performed after this product has been used.

Central retinal vein occlusion during remission of ulcerative colitis.

BACKGROUND Retinal vascular disease is a rare complication of ulcerative colitis. CASE We report a patient who developed unilateral nonischemic central retinal vein occlusion (CRVO) (papillophlebitis) without any other retinal vascular disease during remission of ulcerative colitis. OBSERVATIONS The best-corrected visual acuities were 1.5 OD and 0.7 OS. Dilated and tortuous retinal veins and retinal bleeding were seen in the left eye. Macular edema and leakage from the papilla and the retinal veins of the left eye were evident on fluorescein angiography. After increased dosage of systemic prednisolone was prescribed, the retinal vascular changes resulting from CRVO (papillophlebitis) in the left eye gradually abated. CONCLUSIONS Retinal vascular diseases should be monitored during both remission and activation of intestinal symptoms of ulcerative colitis.

A Case of Uveitis Associated With Idiopathic Retroperitoneal Fibrosis

We treated a patient with nongranulomatous panuveitis associated with idiopathic retroperitoneal fibrosis who had symptoms of abdominal pain, severe fever, leg edema, and blurred vision. A high C-reactive protein level, a high erythrocyte sedimentation rate, anemia, and abnormalities of the immune system were seen. Retrograde pyelography disclosed persistent ureteral obstruction. A computed tomographic scan and magnetic resonance imaging showed a dense plaque of fibrous tissue around the kidney and hydronephrosis. Biopsy disclosed fibrosis infiltrated with lymphocytes, plasma cells, histiocytes, and eosinophils. A moderate degree of cellular inflammation in the anterior chamber and cystoid macular edema were present at ocular examination. We believe idiopathic retroperitoneal fibrosis to be a new cause of uveitis of suspected autoimmune origin.

Retinal pigment epithelial tear and extensive exudative retinal detachment following blunt trauma

Abstract Background: A peripheral retinal pigment epithelial tear and an extensive exudative retinal detachment caused by choroidal leakage from the denuded Bruch’s membrane are extremely rare. A peripheral retinal pigment epithelial tear has not been reported in an eye with retinochoroidal folds after blunt ocular trauma. Methods: Case report. Results: The course of a large nasal peripheral retinal pigment epithelial tear that occurred after blunt ocular trauma in a patient with retinochoroidal folds was followed. The inferior retinal detachment caused by leakage from the denuded Bruch’s membrane following the development of the tear gradually worsened. Initial treatment with cryotherapy was ineffective, but the retinal detachment eventually resolved after the patient underwent sclerectomy and sclerostomy. Conclusion: A large peripheral retinal pigment epithelial tear can occur in patients with retinochoroidal folds following blunt ocular trauma, and extensive retinal detachment can be induced. Sclerectomy and sclerostomy can be beneficial in patients with an extensive exudative retinal detachment caused by choroidal leakage from the denuded Bruch’s membrane.

Histopathologic retinal changes with intravitreous fluorosilicone oil in rabbit eyes.

Background: Fluorosilicone oil (FSiO, 1,000‐10,000 centistokes), which has a higher density (1.29 g/cm3) than vitreous gel, is useful as an operative tool and a tamponade for the inferior retina during difficult retinal detachment surgery. The occurrence of histopathologic retinal changes after injection of FSiO into the vitreous cavity is controversial. Methods: Retinas obtained from 18 rabbits were evaluated histopathologically within 8 weeks of injection into the vitreous cavity of purified FSiO or balanced salt solution as control in phakic eyes. The histopathologic retinal changes caused by FSiO were compared with those of previously reported high‐density hydrophobic vitreous substitutes, such as silicone‐fluorosilicone copolymer oil (SiFO) and perfluorocarbon liquids. Results: By light and electron microscopy, all retinas injected with FSiO were the same as control retinas within 2 weeks of the injection, but the outer plexiform layer disappeared from the inferior retina 4 weeks after injection. The receptor cell nuclei migrated to the photoreceptor layer in the inferior retina 8 weeks after injection. However, no preretinal membrane, including foam cells, was found in any eye injected with FSiO. Conclusion: FSiO may be useful as a temporary vitreous substitute in difficult inferior retinal detachments. RETINA 20:532‐536, 2000

Effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography in the perfused cat eye.

The effects of the β1-selective adrenergic antagonist betaxolol on electroretinography (ERG) were studied in the isolated and arterially perfused cat eye. Betaxolol increased the perfusion flow rate, significantly at the administrations of more than 50μM concentrations and induced a dose-related, reversible increase in the amplitudes of both the a-wave and b-wave of ERG. These results suggest that the calcium-channel blocking mechanism of betaxolol has a beneficial influence on ocular blood flow and retinal electrical activity in response to light. As it is known that ERG is a good indicator of the functional integrity of the retina, this indicates that betaxolol could be an ideal drug for treating glaucoma in which ischemia is involved to some extent.