Very high frequency ultrasound analysis of a new phakic posterior chamber intraocular lens in situ.

PURPOSE: To use very high frequency ultrasound scanning for in situ analysis of a new phakic posterior chamber intraocular lens (No-Touch; International Visions Inc, Cincinnati, Ohio). METHODS: In this pilot study, very high frequency ultrasound (50 MHz) wide-angle (15 mm) full anterior segment scans were obtained in two patients who had undergone phakic posterior chamber intraocular lens implantation into legally blind eyes with normal anterior segment anatomy. RESULTS: Very high frequency ultrasound B-scan images delineated the phakic posterior chamber intraocular lens within the posterior chamber. The relations to the sulci were clearly imaged. Anatomic relations of the phakic posterior chamber intraocular lens optic and haptics were visualized in both static (light/dark) and kinetic (distance/accommodative) states. CONCLUSION: Very high frequency ultrasound wide-angle scanning provides a unique tool to noninvasively evaluate the eye preoperatively and the static and kinetic relations of this new refractive device within the posterior chamber.

The lack of an effect of intraocular steroids on irradiated fibroblasts in experimental proliferative vitreoretinopathy.

Contraction of intraocular membranes is an important event in the development of proliferative vitreoretinopathy (PVR). When sufficient numbers of cells are present in the vitreous cavity, the retina usually detaches as a result of the contractive force generated by these cells. Steroids reduce the occurrence of retinal detachments in rabbit models of PVR by inhibiting the proliferation of injected fibroblasts. In this study, we used non-proliferative, irradiated cells to determine a possible effect of steroids on preretinal membrane contraction in PVR. We found no clinical difference between steroid treated eyes and sham-treated control eyes. Surgical reduction of the contractile tissue and medical therapy to prevent reproliferation are necessary in order to treat PVR effectively.

The effect of triamcinolone acetonide on a refined experimental model of proliferative vitreoretinopathy.

Animal models of proliferative vitreoretinopathy in which the intact vitreous body is injected with large numbers of fibroblasts do not resemble the human situation. Using a refined rabbit model of proliferative vitreoretinopathy in which the vitreous is compressed and partially detached from the retinal surface and small amounts of tissue-cultured homologous fibroblasts (25,000) are scattered over the vascularized part of the retina, we reevaluated the effect of intravitreally injected triamcinolone acetonide. We found that 2 mg of the corticosteroid reduced the incidence of retinal detachments from 90% to 56%. The effect was less than in previous models with intact vitreous. Large doses of the corticosteroid had no additional effect on the reduction of retinal detachments, indicating an optimal dosage of 2 mg. The effect of the corticosteroid on neovascularization was considerable; with 8 mg it could almost be prevented (reduction from 74% to 8%).

Cryotherapy for retinoblastoma.

Cryotherapy was applied to 138 intraocular retinoblastoma tumors from 113 patients who were followed up for a mean of 40 months (four to 144 months). Overall, 70% of tumors were cured with cryotherapy and 93% of patients treated with cryotherapy survived. Twenty-one tumors were treated initially with cryotherapy alone, and 20 such tumors were cured. Twenty-seven new tumors appeared in eyes after radiation therapy and of these, 23 were cured with cryotherapy. Thirty-nine tumors were treated with cryotherapy after unsuccessful treatment with external beam irradiation, and 35 were cured with cryotherapy. Twenty-eight patients developed implantation seeds at the vitreous base after external beam irradiation but cryotherapy failed in each of these cases. There were few long-term ocular complications from cryotherapy despite intensive, heavy, and repeated cryotherapy. The limiting factor that determines success of cryotherapy is the size, elevation, and location of the tumor.