Lennart Berglin

Transplantation of RPE in age-related macular degeneration: Observations in disciform lesions and dry RPE atrophy

Abstract• A study was carried out to investigate whether human RPE allografts are tolerated or rejected in the subretinal space and to determine the feasibility of RPE transplantation in subjects with age-related macular degeneration (AMD). • Methods: Patches of human fetal RPE (13–20 weeks of gestational age) were transplanted into the subretinal space of five patients after surgical removal of subfoveal fibrovascular membranes, and to four subjects with dry geographic atrophy. Suspensions of RPE cells were transplanted to four other patients with nonexudative AMD. Results were evaluated with clinical ophthalmological examination, SLO microperimetry and fluorescein angiography over 8–20 months. • Results: In disciform lesions, RPE transplants developed macular edema and fluorescein leakage concomitant with gradual reduction of visual acuity, implying host-graft rejection, over 1–6 months. In geographic atrophy, three of four transplants showed little change in shape and size after 12 months (one transplant was slowly rejected). In non-exudative AMD, RPE suspension transplants showed no evidence of rejection and were associated with the disappearance of drusen; visual acuity remained stable and SLO microperimetry confirmed retinal function over the transplanted area. • Conclusion: Human RPE allografts are not invariably rejected in the subretinal space without immunosuppression. The rejection rate is lower in nonexudative than in neovascular AMD. An intact blood-retinal barrier is likely to protect against rejection. It is technically feasible to transplant human RPE into the submacular space without adversely affecting visual function in nonexudative AMD over relatively long periods of time

Immunohistochemical characterization of surgically removed subfoveal fibrovascular membranes

Eighteen patients with age-related macular degeneration developed subfoveal membranes that were surgically removed and submitted for histopathological examination. Immunohistochemical techniques were performed, using a panel of monoclonal antibodies recognizing retinal pigment epithelial (RPE) cells, myofibroblasts, pericytes, endothelial cells, glial cells, smooth muscle cells and various types of macrophages. The PC10 antibody to proliferating cell nuclear antigen (PCNA) was applied as a marker of proliferating cells. The specimens displayed a core of neovascular stroma surrounded by a rim of more fibrous tissue. All specimens contained abundant RPE cells that in some cases appeared to envelop part of the membrane. Most cases had basal laminar deposits and thickened basement membrane material adjacent to the RPE cells suggestive of parts of Bruchs membrane. Often this Bruchlike membrane appeared at the surgical margin, forming a surgical cleavage plane. Chronic inflammatory cells were abundant, but polymorphonuclear leukocytes were notably absent. Nearly all specimens contained myofibroblasts and various types of macrophages. The presence of myofibroblasts suggests subretinal membrane contraction, which may induce new breaks and other pathology in RPE layer and Bruchs membrane.

Photoreceptor decay over time and apoptosis in experimental retinal detachment

Background: Data are scarce on the actual rate and mode of outer nuclear layer decay in retinal detachment (RD). We used an experimental rabbit model to assess the presence of apoptosis and rate of photoreceptor death following RD. This model included the creation of localized and stable retinal blebs, while controlling for any decline of retinal elevation over time.Methods: RD was produced in New Zealand white rabbits by injecting 0.05 ml of 15% sodium hyaluronate (Healon GV) under the neural retina using a microsurgical technique. Animals were killed at 1, 2, 4, 7, 14 and 29 days. Retinal tissue was processed for light and electron microscopy and for in situ end labeling of fragmented DNA using a modification of the TUNEL technique. Photoreceptor cell nuclei were counted in the RD areas of maximum retinal elevation of 28 eyes, and an additional 4 eyes were used for nick end labeling.Results: Positive DNA nick end labeling, ultrastructural features and absence of necrotic cells indicated apoptotic photoreceptor cell death. Also, there was a rapid, almost linear elimination of photoreceptor nuclei over time. At 14 days only half of the number of nuclei were discernible, while approximately one tenth remained after 29 days. There was a statistically significant, but minimal decline in RD height over the 4 weeks of study.Conclusion: Following experimental RD in rabbits, apoptotic cell death is associated with an almost linear elimination of photoreceptor cells over time. The use of highly viscous sodium hyaluronate in separating the neural retina from the retinal pigment epithelium allows the RD to maintain a nearly constant height over a period of 4 weeks.

Retinal detachment and degeneration in response to subretinal perfluorodecalin in rabbit eyes

Perfluorocarbon liquids, including perfluorodecalin (PFD), are useful intraoperative tools in complicated vitreoretinal surgery, such as for giant retinal tears, PVR and intraocular foreign bodies. Due to its high specific gravity (1.91 g/cm3) subretinal complications of PFD may occur. The consequences of subretinal PFD were studied in 23 albino rabbits (28 eyes). Using glass micropipettes (outer diameter of tip 100–120 qm), we injected 50–100 μl PFD subretinally via the vitreous space. The same volume of BSS was injected into 18 control eyes. Eyes were monitored by indirect ophthalmoscopy and examined by light and electron microscopy at 1, 2 and 3 days, and 1, 2, 4 and 12 weeks. Progressive retinal detachments with newly formed retinal breaks in the inferior quadrants developed in 26 of 28 eyes. As early as 1 day postoperatively, subretinal PFD induced loss of outer and inner segments. Local retinal necrosis occurred in 4 eyes 5–7 days after surgery. A marked vacuole formation in retinal layers and PFD emulsification were regularly seen. The control eyes healed spontaneously. Toxic, mechanical and barrier effects may have caused the retinal damage. We advocate that all PFD be removed from the eye at surgery.

Tolerance of human fetal retinal pigment epithelium xenografts in monkey retina

Abstract• Background: RPE transplantation offers the possibility of treating certain forms of retinal degeneration. Understanding how to optimize the surgical technique for performing RPE transplantation, especially in primates, is therefore of considerable interest. • Methods: Fifteen patch RPE transplants were performed in six monkeys. The transplant sites were examined at follow-up by ophthalmoscopy, biomicroscopy, fluorescein angiography and histology. Foveal and peripheral retinal transplants were compared. • Results: Human fetal RPE xenografts can survive without rejection for at least 6 months after transplantation in monkey retina. Such grafts form a basal lamina and make intimate contacts with the outer segments of the host. Both rods and cones retain a normal appearance when in contact with unrejected transplants. Rejection occurred in only 30% (3/10) of the peripheral but in 60% (3/5) of the foveal transplants. • Conclusions: Cultured human fetal RPE patch transplants can survive and maintain local photoreceptor integrity for relatively long periods of time in monkey subretinal space without immunosuppression. Rejection, when it occurs, is more frequent near the fovea.

Anatomic Alterations in Aging and Age-Related Diseases of the Eye

PURPOSE We described anatomic age-related changes in the human eye to determine potential areas of investigation that may lead to identifying eyes at risk for age-related disease. METHODS A descriptive review of anatomic changes in the eye related to aging was performed in the context of current areas of investigation. The review was performed specifically for differing anatomic ocular structures, including cornea, trabecular meshwork, lens, uveal tract, Bruchs membrane, retina, RPE, vitreous, sclera, and optic nerve. RESULTS Age-related changes occur in all ocular tissues. The cornea flattens and there is an attrition of endothelial cells. The shape of the trabecular meshwork changes and there is a loss of trabecular endothelium. The lens grows and becomes cataractous. The ciliary body becomes collagenized, there are choroidal vascular changes, and Bruchs membrane thickens. Retinal vessels become hyalinized and there is a loss of rods before cones in the macula. RPE morphometric changes occur with aging. The vitreous becomes liquefied and there is a loss of vitreous compartmentalization. The sclera becomes rigid and may become calcified. The optic nerve exhibits structural changes with age. CONCLUSIONS There are numerous anatomic age-related changes in the human eye. Current areas of investigation related to these changes include adaptive optics scanning laser ophthalmoscopy imaging of the RPE mosaic in the context of aging, and drug delivery devices that overcome age-related alterations to retinal and macular perfusion.

Limbal sub-Tenon's administration of retrobulbar anesthesia using a blunt irrigating cannula.

BACKGROUND AND OBJECTIVE To eliminate sharp needles when administering local anesthesia to the eye in order to reduce serious complications caused by needle perforation. PATIENTS AND METHODS After topical anesthesia, limbal conjunctival incision, and sub-Tenons dissection, a retrobulbar irrigation of an equal mixture of bupivacaine (5 mg/ml) and lidocaine (20 mg/ml) was given using a blunt cannula. RESULTS The technique was used in both vitreoretinal surgery (n = 70) and anterior segment surgery (n = 235) with good analgesic and akinetic effects. No serious adverse were noted. CONCLUSION This proved to be a safe and efficient technique that abandoned the use of sharp needles.

Ocular Perforation During Retrobulbar and Peribulbar Injections

BACKGROUND AND OBJECTIVE To determine the ocular perforations during retrobulbar and peribulbar injections. PATIENTS AND METHODS Twenty-five ocular perforations between 1976 and 1993 occurred after 13 retrobulbar and 12 peribulbar injections. Eighteen patients (72%) were women. Eighteen eyes were myopic (72%). Risk factors included high myopia in 11 cases (44%), use of Atkinson gaze in 21 cases (84%) and a sharp injection needle. RESULTS Deep position of the posterior pole was common. Perforation signs comprised vitreous hemorrhage in 25 eyes (100%), subretinal hemorrhage in 19 eyes (76%), retinal breaks along the inferior vascular arcade in 19 eyes (76%), and retinal detachment in 14 eyes (56%). Proliferative vitreoretinopathy developed in 11 eyes (44%). CONCLUSION Retinal detachment strongly correlated to poor visual outcome.

Healon® Yellow as a Surgical Tool in Maneuvering Intraocular Tissues

Tinted sodium hyaluronate (Healon Yellow) was used during posterior segment surgery mainly for the dissection of epiretinal membranes in cases of proliferative diabetic retinopathy and macular pucker. The yellow color facilitated injecting the viscoelastic substance under the membranes and simplified its removal at the end of surgery.

Sealing of retinal breaks with metal tacks: Evaluation of a new procedure in retinal re-attachment surgery

Abstract Metal retinal tacks were used in 18 patients with complicated retinal detachments, such as giant tears (3 cases), severe proliferative vitreoretinopathy (PVR) (7 eyes) and diabetic traction and rhegmatogenous detachment (8 cases). All eyes had undergone vitreous microsurgery, including excision or segmentation of epiretinal membranes, fluid‐air (SF6) or silicone oil exchange. Retinal breaks and the cut edges of retinotomies and retinectomies were successfully sealed by metal tacks. Retinal re‐attachment was achieved in 9 cases and partial re‐attachment in another 5 eyes (follow‐up 3–6 months). Retinal tears in diabetic macular detachment associated with extensive epiretinal fibro‐vascular membranes were also successfully sealed despite persisting traction. Our first experience indicates that the closing of retinal breaks with metal tacks is a major step forward in retinal re‐attachment surgery.