Maurice B. Landers

The Use of Silicone Oil Following Failed Vitrectomy for Retinal Detachment with Advanced Proliferative Vitreoretinopathy

We have used silicone-oil injection in a consecutive series of 44 patients with retinal detachment and advanced proliferative vitreoretinopathy, all of whom had previously failed to reattach with vitrectomy, membrane peeling, and scleral buckling. After a minimal follow-up period of 6 months, complete anatomic retinal reattachment posterior to the encircling scleral buckle was obtained in 64% of these eyes. Ambulatory visual acuity (5/200 or better) was achieved in 57% of the anatomically successful cases. Silicone-oil removal was performed in 69% of the anatomically and visually successful eyes without recurrent retinal detachment. Because of the frequent and severe complications associated with the use of silicone oil, we recommend that silicone-oil injection be considered only when conventional vitreoretinal techniques have failed to achieve retinal reattachment.

Long-Term Results of Successful Vitrectomy With Silicone Oil for Advanced Proliferative Vitreoretinopathy

We have analyzed the six-month, one-year, and two-year follow-up examinations in 47 patients who had silicone oil injection in combination with revision of vitrectomy for intractable retinal detachment and advanced proliferative vitreoretinopathy. A visual acuity of 5/200 or better was attained in 22 eyes at six months (47%), 17 eyes at one year (36%), and 14 eyes at two years (30%). Of eyes that were completely attached posterior to the buckle at six months, 77% remained attached at two years. In those eyes that were attached at six months, corneal decompensation was the most frequent cause of a loss of vision between six months and two years. Silicone oil was removed in 22 eyes (47%).

Silicone oil in vitreoretinal surgery part 2: Results and complications

The surgical results and postoperative complications associated with silicone oil injection in the treatment of complicated retinal detachment were evaluated in a series of 164 eyes followed for a minimum of 6 months. The incidence of recurrent retinal detachment, corneal decompensation, cataract, glaucoma, and hypotony were noted to be high, and the final visual results were often disappointing. The avoidance and treatment of these complications are discussed, and removal of the silicone oil after sustained anatomic retinal reattachment has been attained is recommended. RETINA 5:198-205, 1985

Oxygenation and vasodilatation in relation to diabetic and other proliferative retinopathies.

The features of proliferative retinopathies are reviewed with reference to the vasodilatation that is a common stage in their pathogenesis. Vasodilatation in the retina is discussed in terms of a model in which vessel wall stretch in the retinal venules leads to leakage and proliferation. The beneficial effects of treatments such as panretinal photocoagulation and vitrectomy on the retinal hemodynamics are shown to agree with the hypothetical model.

Panretinal photocoagulation and retinal oxygenation.

Panretinal photocoagulation destroys some of the photoreceptors and thereby reduces the oxygen consumption in the outer retina and allows more O2 to flow from the choroid to the inner retina. Measurements of the preretinal oxygen tension were made in rhesus monkeys that had portions of their retinas photocoagulated. With the animal breathing one atmosphere O2, the oxygen tension over photocoagulated areas of retina was significantly higher than the PO2 over normal, untreated areas of retina. It is proposed that the therapeutic effect of panretinal photocoagulation in diabetic retinopathy lies in the oxygenation of the inner retina from the choroid.

In vivo O2 consumption in rhesus monkeys in light and dark.

The rate of oxygen consumption in retinas in vitro has been measured in a great number of species, but in vitro estimates have varied partly because the rate of O2 uptake depends heavily upon the composition of the buffered solution used to maintain the retina. The in vitro experiments on frog retinas show a greater O2 consumption in dark than in light conditions, and indicate marked differences in metabolism between light and dark conditions. A method was developed to estimate retinal oxygen consumption in vivo. We evaluated the oxygen consumption of the in vivo Rhesus monkey retina with an intraocular oxygen microelectrode. The intact monkey retina consumes more oxygen in darkness than in light.

Vitrectomy, lensectomy, and ocular oxygenation.

The effect of vitrectomy and lensectomy upon the anterior chamber oxygen tension of the cat eye was measured polarographically. After vitrectomy and lensectomy alone, a reduction of 12 mm Hg (35%) was observed and when retinal veins were also partially occluded, a reduction of 17 mm Hg (50%) was measured as compared with the normal oxygen tension (PO2) of 34 mm Hg. If vitrectomy and lensectomy allow aqueous to deliver oxygen from the anterior part of the eye to the retina, the poorer oxygenation of the iris and the improved oxygenation of the retina might explain both the development of rubeosis iridis and stabilization of proliferative diabetic retinopathy so commonly seen following vitrectomy.

Vitreous Hemorrhage after Intracranial Hemorrhage

Eight patients, aged 2 months to 55 years, developed vitreous hemorrhages as a result of subarachnoid or subdural bleeding. Subhyaloid hemorrhages were associated with, or preceded, hemorrhage into the vitreous cavity in four cases. Most vitreous hemorrhages cleared spontaneously, several months later, without major visual sequelae. In one patient, intravitreal blood persisted after 28 months. Vitreous hemorrhage can be a serious complication in patients surviving subarachnoid or subdural hemorrhages and, though uncommon, probably occurs with greater frequency than previously acknowledged. While vitrectomy may be a reasonable therapeutic approach in selected cases, in most instances vitreous hemorrhage following intracranial hemorrhage should be treated conservatively.

Temporary Keratoprosthesis for Use During Pars Plana Vitrectomy

We have developed a series of temporary keratoprostheses that permit closed pars plana vitrectomy in eyes with abnormal corneas. These devices are placed into a trephined opening in the cornea, and provide a clear, stable view of the intraocular contents. Immediately after vitrectomy, the keratoprosthesis is replaced with a corneal graft. We have used this technique successfully in four eyes with opaque or severely traumatized corneas.

Fibrinolytic-assisted Removal of Experimental Subretinal Hemorrhage within Seven Days Reduces Outer Retinal Degeneration

PURPOSE To better determine the surgical window for removing experimental subretinal hemorrhages in the cat model and to compare the histopathologic effect of such removal with the natural history of untreated subretinal hemorrhages. METHODS Twenty-three large experimental subretinal hemorrhages were created with a neodymium:YAG laser focused through a performed retinal bleb in a cohort of cats. Fourteen subretinal hemorrhages were observed without treatment, six were removed at 7 days through a micropipette after injecting 10 micrograms/ml of human recombinant tissue plasminogen activator (rt-PA) into the subretinal space, and three were removed through an access retinotomy without the use of rt-PA. The tissues from these eyes were examined with light and electron microscopy 14 to 28 days after creation of the subretinal hemorrhages. RESULTS Severe outer retinal degeneration was evident by day 14 in all of the untreated subretinal hemorrhages 3 disc diameters or greater in size. In contrast, the outer retinal architecture was better preserved in the eyes that underwent rt-PA-assisted removal of their subretinal hemorrhage that was 3 disc diameters or greater on day 7. In these eyes, mild abnormalities such as abnormally short and misaligned photoreceptor outer segments with vacuolization were present within the retina that was formerly located over the hemorrhage center. The eyes that underwent subretinal hemorrhage removal through an access retinotomy without rt-PA on day 7 had a low-lying retinal detachment and outer retinal degeneration. CONCLUSION Removing experimental subretinal hemorrhages within 7 days of their occurrence with the assistance of rt-PA and an ultramicrosurgical approach may reduce outer retinal degeneration in the cat model.