Evaluation of retinal damage induced by air/fluid exchange using a trypan blue inclusion test in rabbits.

PURPOSE: To investigate whether retina damaged in the process of air/fluid exchange could be visualized in situ using trypan blue staining. METHODS: Vitrectomy and air/fluid exchange with continuous air infusion for various periods of time was performed in adult pigmented rabbits, followed by injection of 0.4% trypan blue solution into the vitreous cavity. Retinal staining was evaluated intraoperatively under the operating microscope and by light microscopy after enucleation. RESULTS: Intraoperative examination showed localized trypan blue staining of areas of the retina opposite the infusion cannula. Light microscopy of the same areas revealed intranuclear trypan blue inclusion in the retina. CONCLUSION: Trypan blue staining allows for the immediate in situ evaluation of damage to the retina associated with air/fluid exchange and continuous air infusion in rabbit eyes.

Ultrasound biomicroscopy for examination of the sclerotomy site in eyes with proliferative diabetic retinopathy after vitrectomy.

PURPOSE: We evaluated the capability of ultrasound biomicroscopy (UBM) to predict fibrovascular proliferation at sclerotomy sites in eyes with postoperative vitreous hemorrhage due to proliferative diabetic retinopathy (PDR). METHODS: Ultrasound biomicroscopy was used for examining the sclerotomy sites in 13 eyes of 11 patients with PDR experiencing postoperative vitreous hemorrhage (PDR group). Thirty-nine sclerotomy sites (all entry sites of each eye) were examined before reoperation, and the UBM images were compared with findings obtained during revision of the vitrectomy. Thirteen eyes of 13 patients undergoing vitrectomy for nondiabetic diseases were used as controls and examined after vitrectomy. RESULTS: The UBM images were classified into the following four categories: A, tent; B, spheroid; C, trapezoid; and N, none. The findings were distributed as follows in the PDR group: category A, 18%; B, 5%; C, 56%; and N, 21 %; and as follows in the control group: category A, 28%; B, 5%; C, 5%; and N, 62%. In the PDR group, 11 of 12 sclerotomy sites disclosing fibrovascular proliferation possessed the trapezoidal image. Mean length of trapezoidal base was 2.49+/-0.97 mm and 1.51+/-0.75 mm in the groups with and without fibrovascular proliferation, respectively (P<0.01). The average relative reflectivity of the trapezoidal image against the sclera was 0.501+/-0.169 in the fibrovascular proliferation group and 0.891+/-0.183 in the fibrous ingrowth group (P<0.01). CONCLUSION: Ultrasound biomicroscopy is useful in detecting fibrovascular proliferation at sclerotomy sites because a large and low-reflecting trapezoidal UBM image is highly correlated to its presence.

Orbital high resolution magnetic resonance imaging with fast spin echo in the acute stage of Leber's hereditary optic neuropathy.

Some evidence suggests that the primary locus of the lesion in Leber's hereditary optic neuropathy (LHON) may be intraocular rather than retrobulbar. To clarify this issue, the condition of the retrobulbar portion of the optic nerve was evaluated in patients with the acute stage of LHON. High resolution MRI with fast spin echo sequences of the optic nerve complex in the orbit was carried out. Five patients with acute stage LHON were compared with seven patients with acute stage optic neuritis. On T2 weighted fast spin echo MRI, signal changes did not appear in the retrobulbar optic nerve complex in acute stage LHON. By comparison, patients with optic neuritis showed pronounced high signals in the optic nerve. Subsequent orbital MRI in the atrophic stages of the same patients with LHON showed an increase in signal intensity in the optic nerve toward the orbital apex in both eyes. The present results support the hypothesis that a primary lesion in LHON may be intraocular.

High-resolution magnetic resonance imaging of the intraorbital optic nerve and subarachnoid space in patients with papilledema and optic atrophy.

OBJECTIVE: To evaluate the orbital portion of the optic nerve and the subarachnoid space using fast spin-echo magnetic resonance imaging in normal subjects and in patients with papilledema or optic atrophy. DESIGN: Measurements of the optic nerve complex on coronal images were made using high-resolution magnetic resonance imaging with fast spin-echo sequences. PATIENTS: Twenty-one patients, including 5 patients with papilledema due to congenital hydrocephalus, intracranial tumors, or meningitis, as well as 16 patients with optic atrophy, were studied. Sixteen healthy volunteers served as controls. MAIN OUTCOME MEASURES: The longitudinal diameter of the optic nerve, the longitudinal outer diameter of the subarachnoid space, the diameter ratio, and the area of the subarachnoid space were determined. RESULTS: In normal subjects, the ring-shaped area of high signal intensity that represented the subarachnoid space was widest behind the globe, then narrowed toward the orbital apex. In patients with papilledema, the area of the subarachnoid space was markedly dilated, the optic nerve was compressed, and the nerve sheath was widened, resulting in a small diameter ratio compared with that of controls. Patients with pallor of the temporal aspect of the optic disc appeared to exhibit dilation of the subarachnoid space; the size of the optic nerve was decreased more than that of the nerve sheath, resulting in a small diameter ratio compared with controls. Patients with complete pallor of the disc, however, exhibited hyperintense optic nerve complexes without a ring-shaped appearance toward the orbital apex. CONCLUSION: Fast spin-echo magnetic resonance imaging appears useful for objectively evaluating the optic nerve and surrounding subarachnoid space in patients with papilledema and optic atrophy.

[Rapidly progressive outer retinal necrosis in a patient with acquired immunodeficiency syndrome].

We report a case of rapidly progressive varicella zoster virus retinitis, which is distinct from acute retinal necrosis syndrome. The patient was a 52-year-old male and suffered acquired immunodeficiency syndrome. Two months after the varicella zoster dermatitis in the distribution of the first division of the left trigeminal nerve, pseudodendritic keratitis and iridocyclitis were observed in the left eye. After 5 weeks, multifocal and patchy white exudates were observed in the peripheral deeper layer of the retina in the left eye, but retinal vasculitis in the exudative lesions was slight. Despite systemic administration of acyclovir, white exudates progressed confluently from the periphery to the post pole of the retina and reached the macula in 10 weeks. Eight weeks after the observation of lesions in the left eye, we found the same lesions in the right eye. After the white exudative lesions disappeared, the retina became atrophic and the retinal vessels were narrowed, but no retinal detachment was observed. Recently, Foster and associates described the rapidly progressive outer retinal necrosis as a new entity of varicella zoster virus retinitis in AIDS patients. We think our case was very similar to the rapidly progressive outer retinal necrosis. This case shows that we must carefully follow up the rapidly progressive outer retinal necrosis in the AIDS patients with a varicella zoster dermatitis.