Internal eye wall resection in the management of uveal melanoma

Twenty patients with presumed uveal melanoma underwent internal eye wall resection. It was the primary procedure in 13 patients who had tumours within 2 disc diameters of the optic nerve head and was combined with external resection in the remainder. Malignant melanoma was confirmed histologically in 15 patients; the diagnosis was a benign tumour in the other 5. The length of follow-up ranged from 2 to 37 (mean 19) months. In all cases the retina was completely attached at the time of last examination. The visual acuity ranged from 20/40 to hand movements; nine patients had an acuity of 20/400 or better. At the time of writing no metastatic disease or local recurrence had developed in any of the 15 patients in whom malignant melanoma was diagnosed.     

Trans-scleral application of a semiconductor diode laser

We used a diode laser with an output power of 1 W through a fiberoptic light pipe (200 microns diameter) to deliver laser energy through the sclera of pigmented rabbits. Ciliary body destruction occurred with energy levels of 300-400 mW and exposure time of 0.5 sec. Retinal photocoagulation was achieved with energy levels of 200-500 mW in 0.5 sec. Histologic examination of acute lesions demonstrated thermal destruction of ciliary body processes and retina. Chorioretinal scar formation was observed clinically and histologically within 2-3 weeks. Our data indicate that the transscleral diode laser may be used for destruction of the ciliary body processes or peripheral retinal coagulation in pigmented eyes.     

Syphilitic gummatous iridocyclitis

We present a rare case of gummatous syphilitic iridocyclitis. The differential diagnosis, clinical characteristics, and treatment of this ocular disease are discussed.     

Intraocular acyclovir levels after subconjunctival and topical administration.

Substantial levels of acyclovir were detected in the aqueous and vitreous of New Zealand rabbits at various time intervals following subconjunctival injection. Intravitreal penetration of acyclovir after topical application was poor.     

Acute retinal necrosis

Five patients with the acute stages of acute retinal necrosis underwent vitrectomy, with acyclovir in the infusion fluid, and the placement of a 360 degrees scleral buckle after intravenous therapy with acyclovir. Anatomic reattachment was achieved in all patients, and improvement over preoperative visual acuity was obtained in four. Recommendations for the treatment of acute retinal necrosis include a high index of suspicion in healthy patients with retinitis, early diagnosis, early intravenous therapy with acyclovir, early pars plana vitrectomy with the use of intravitreal acyclovir in the infusion fluid, and a 360 degrees scleral buckling procedure.     

Comparative study of three fluorescent dyes for angiography: sodium fluorescein, carboxyfluorescein, and calcein

To compare the characteristics of carboxyfluorescein (CF) and calcein (Calc) with those of sodium fluorescein (Naf), the only fluorescent dye currently in clinical use, we performed angiography in rabbits and primates using these three dyes. The circulation decay time of all dyes was longer in primates than in rabbits. In primates, CF and Calc had longer decay times than Naf. Calc produced the greatest contrast between the choroidal and retinal vasculature. Tissue staining and dye leakage into the vitreous immediately after retinal photocoagulation were minimal with Calc, moderate with CF, and marked with Naf. The limited leakage and longer circulation time of Calc may permit simultaneous angiography and photocoagulation therapy without obscuring the fundus view with leaking dye from the photocoagulated structure.     

Intravitreal liposome-encapsulated gentamicin in a rabbit model. Prolonged therapeutic levels

The authors investigated the effect of liposome encapsulation on the pharmacokinetics of gentamicin after intravitreal injection in albino rabbits, using immunofluorescent assay. Gentamicin was encapsulated into liposomes of phosphatidylcholine, phosphatidic acid, and alpha-tocopherol. The final liposomal suspension contained gentamicin, 10 mg/ml, 95% encapsulated. One eye of each rabbit received an intravitreal injection (100 mg gentamicin per 0.1 ml) of either liposome-encapsulated gentamicin (LEG) or gentamicin in phosphate-buffered saline (Gs). Equilibrium dialysis separated free from encapsulated drug in vitreous samples. The peak free drug concentration was significantly less (P less than .01, unpaired t-test) with LEG than with Gs. Concentrations of free and total gentamicin were significantly greater (P less than .05) with LEG than with Gs at 24, 72, 120, and 192 hr. LEG gave a twofold increase in area under the drug concentration time curve for total drug, and a 1.5-fold increase for free drug when compared to Gs.     

Effects of an erbium:YAG laser on ocular structures

We evaluated the effects of the erbium:YAG laser (2.9 m wavelength) on ocular structures. Energy was successfully transmitted through a fiberoptic bundle for intraocular and extraocular applications. The wavelength was strongly absorbed by ocular tissues, producing ablations with minimal thermal damage. Our results indicated that the erbium: YAG laser may have potential uses as a photoablative tool to reshape the corneal surface and as a surgical knife.