Visual task performance in blind humans with retinal prosthetic implants.

A prototype electronic retinal prosthesis has been tested in three subjects. The system features an implanted retinal stimulator and an external system for image acquisition, processing, and telemetry. The subjects in general performed better than chance on psychophysical tests involving object detection, object counting, object discrimination, and direction of movement.

Visual and electrical evoked response recorded from subdural electrodes implanted above the visual cortex in normal dogs under two methods of anesthesia.

Sensitive methods are required to record electrical evoked potentials over the visual cortex to evaluate the efficacy and safety of a retinal prosthesis before it can be implanted on the retinal surface of patients afflicted by outer retinal diseases. This study was designed to examine subdural electrodes as a mean to evaluate cortical evoked potentials in response to light and electrical stimulation of the retina in three dogs under two methods of anesthesia-halothane and propofol. Results showed that subdural electrodes could be stabilized over the visual cortex for several (3-5) months, and that they were 6.95 times more sensitive than subdermal electrodes in recording cortical visual evoked potentials (VEPs) and 4.31 times more sensitive in recording cortical electrical evoked potentials under both methods of anesthesia. The waveforms' shape changed for each electrode in the subdural array during 6/6 (100%) and 20/38 (52%) multi-channel recording sessions under halothane and propofol, respectively. This change could point to a cortical retinotopic organization versus hierarchical organization of different cortical areas for a given retinal stimulus. In summary, subdural electrodes show promising results for recording visual and electrical evoked responses (EERs) and thus for evaluation of the retinal prosthesis.

Effective nasal limited macular translocation.

PURPOSE: To describe a case of effective foveal displacement toward the optic disk (nasal limited macular translocation) in a patient with a large subfoveal choroidal neovascularization secondary to age-related macular degeneration. METHODS: Case report. RESULTS: A 77-year-old white man presented with decreased vision of 20/400 due to subfoveal predominantly occult CNV secondary to age-related macular degeneration in the left eye. The CNV, measuring 9 Macular Photocoagulation Study disk areas in size, was centered temporally relative to the fovea with a minimum desired translocation of 650 microm for nasal macular translocation. The patient underwent nasal LMT with punctate retinotomy and temporal chorioscleral infolding, followed by postoperative head-positioning on his right side. Effective LMT was achieved with a postoperative nasal foveal displacement of 1400 microm. The entire CNV was ablated with laser photocoagulation postoperatively. His vision improved to 20/40 6 months postoperatively. CONCLUSION: Nasal LMT is feasible and may be considered in patients with subfoveal CNV centered temporally relative to the fovea.

Transient formed visual hallucinations following macular translocation for subfoveal choroidal neovascularization secondary to age-related macular degeneration.

PURPOSE: To report the occurrence of transient formed visual hallucinations following macular translocation. METHODS: Two case reports. RESULTS: Two white women aged 84 and 83 years with bilateral age-related macular degeneration and unilateral subfoveal choroidal neovascularization underwent macular translocation with punctate retinotomy (limited macular translocation) and chorioscleral infolding in the eye with neovascularization. They complained of formed visual hallucinations which began within 24 hours following macular translocation and ceased 7 and 3 days postoperatively, respectively. Their symptoms occurred in the presence of normal cognition, orientation and insight, were not associated with other psychiatric symptoms, and were characteristic of Charles Bonnet syndrome (CBS). CONCLUSION: The temporary deliberate retinal detachment and/or poor vision following macular translocation may be associated with postoperative CBS, and this report extends the spectrum of conditions associated with CBS.

Macular translocation: unifying concepts, terminology, and classification.

PURPOSE: To describe some unifying concepts, terminology, and classification of macular translocation so as to facilitate communication within the scientific community. METHODS: A panel of ophthalmologists with expertise in macular translocation reviewed available data and developed some unifying concepts, terminology, and classification of macular translocation. RESULTS: Macular translocation may be defined as any surgery that has a primary goal of relocating the central neurosensory retina or fovea intraoperatively or postoperatively specifically for the management of macular disease. It may be classified according to the size of the retinotomy and, where applicable, the technique of chorioscleral shortening used. The direction of macular translocation is denoted by the movement of the neurosensory macula relative to the underlying tissues. Effective macular translocation may be defined as successful intraoperative or postoperative relocation of the fovea overlying a subfoveal lesion to an area outside the border of the lesion. The concepts of minimum desired translocation and median postoperative foveal displacement can give some useful idea of the likelihood of effective macular translocation before surgery. CONCLUSIONS: Use of a common standardized terminology for macular translocation will facilitate communication within the scientific community and enhance further research in this area. However, the definitions, terms, classification, and concepts concerning macular translocation are likely to continue to evolve as macular translocation undergoes further modifications and refinements.

Limited macular translocation for the management of subfoveal retinal pigment epithelial loss after submacular surgery.

PURPOSE: To report a case of subfoveal retinal pigment epithelial (retinal pigment epithelium) loss after submacular surgery managed successfully by limited macular translocation. METHODS: Case report. RESULTS: A 28-year-old woman presented with a visual acuity of 20/100 caused by subfoveal choroidal neovas-cularization secondary to ocular histoplasmosis syndrome. Submacular resection of the choroidal neovascularization was complicated by inadvertent retinal pigment epithelium loss from beneath the foveal center. She underwent limited macular translocation 5 days after the initial surgery and had successful displacement of the fovea to an area inferior to the retinal pigment epithelium defect. Her visual acuity was 20/60 4 months postoperatively. CONCLUSION: This report demonstrates the feasibility of using limited macular translocation for the management of eyes with central retinal pigment epithelium defect after submacular surgery and extends the clinical indications for limited macular translocation.

Initial experience of inferior limited macular translocation for subfoveal choroidal neovascularization resulting from causes other than age-related macular degeneration.

PURPOSE: To report our initial experience of inferior limited macular translocation in patients with subfoveal choroidal neovascularization resulting from causes other than age-related macular degeneration. METHODS: We conducted a retrospective study of 23 eyes of 22 patients with choroidal neovascularization involving the foveal center secondary to pathologic myopia (11 eyes), ocular histoplasmosis syndrome (four eyes), angioid streaks (four eyes), idiopathic neovascularization (three eyes), and multifocal choroiditis (one eye), in which the fovea was moved inferiorly by means of limited macular translocation surgery. The mean preoperative best-corrected visual acuity was 20/150, and in five of 23 eyes (21.7%) the visual acuity was 20/80 or better. The major outcome measures were preoperative and postoperative visual acuity, postoperative foveal displacement, and complications related to the surgery. RESULTS: The mean postoperative follow-up was 10.82 months (range, 6 to 18 months). Postoperative best-corrected visual acuity improved by 2 or more Snellen lines of visual acuity in 11 of 23 eyes (47.82%), remained within 1 line in seven of 23 eyes (30.43%), and worsened 2 or more lines of vision in five of 23 eyes (21.74%). The mean postoperative best-corrected visual acuity was 20/100, and in 12 of the 23 eyes (52.17%) the visual acuity achieved was 20/80 or better. Retinal detachment was the most frequent complication and occurred in six eyes (26%). CONCLUSIONS: Our initial experience with limited macular translocation shows that this treatment modality offers the potential to improve visual function in some eyes with subfoveal choroidal neovascularization secondary to myopia, ocular histoplasmosis syndrome, angioid streaks, idiopathic neovascularization, and multifocal choroiditis. Although longer and more complete follow-up is needed, the results of this initial series warrant further studies to define the precise role of macular translocation in the management of these conditions.

Complications associated with limited macular translocation.

PURPOSE: To report the ocular complications associated with the limited macular translocation procedure. METHODS: Retrospective review of 153 consecutive eyes of 151 patients that had the limited macular translocation procedure for subfoveal choroidal neovascularization between April 1996 and February 1999. The major study variables investigated included the incidence of specific ocular complications and their impact on visual acuity at 3 months after the surgery. In addition, baseline patient characteristics and operative factors were evaluated to determine whether they were significant risk factors for the development of an ocular complication. The existence of a surgical procedure learning process was investigated. RESULTS: One hundred forty-one (92.15%) of 153 eyes achieved at least 3-month follow-up. At least one complication occurred in 53 of 153 eyes (34.6%) and in 51 of these 53 eyes (96. 22%) the complications occurred before 3 months of postoperative follow-up. The intraoperative and postoperative complications included retinal detachment (17.4%), retinal breaks (13.4%), macular holes (7.8%), macular fold (4.6%), and intraocular hemorrhage (vitreous, subretinal, or choroidal; 9.2%). Eyes that developed retinal detachment, subretinal hemorrhage, and macular fold had significantly more loss of visual acuity than eyes without each of these complications (P =.0001, P =.038, and P =.027, respectively). The presence of predominantly classic choroidal neovascularization, the occurrence of an intraoperative retinal break, any intraocular hemorrhage, or macular fold formation were significantly associated with retinal detachment (P =.021, P =.025, P =.013, and P =.014, respectively). The incidence of any complication, retinal detachment, and hemorrhage significantly decreased during the study period, suggesting a learning process (P =.03, P =.006, P =.027, respectively). CONCLUSIONS: A variety of ocular complications can occur during or after limited macular translocation, and some are associated with reduced postoperative visual acuity. Improved surgical techniques and experience may significantly reduce the incidence of these complications.

Limited inferior macular translocation for the treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration.

PURPOSE: To review a series of patients with age-related macular degeneration undergoing limited macular translocation for the treatment of subfoveal choroidal neovascularization, to determine short-term visual acuity outcomes, to measure amounts of attainable retinal movement, and to identify prognostic factors. METHODS: A retrospective review was conducted on a consecutive series of patients undergoing inferior limited macular translocation with scleral imbrication for the treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration. The main outcome measures investigated were distance of macular translocation, visual acuity at 3 and 6 months after surgery, change in visual acuity from baseline, and the development of intraoperative and postoperative complications. Univariate and multivariate analyses of a number of potential prognostic factors were undertaken. RESULTS: Macular translocation was achieved in all 102 eyes (101 patients) included in this study. The range of movement varied from 200 to 2,800 microm with a median movement of 1, 200 microm. Nearly 33% of the study group achieved a visual acuity better than 20/100 at 3 months, and 49% achieved this vision at 6 months. At 3 and 6 months, 37% and 48% of the study group, respectively, experienced 2 or more lines of improvement on visual acuity testing, and by 6 months 16% experienced greater than 6 lines of visual improvement. Good baseline vision, achieving the desired amount of macular translocation, a greater amount of macular translocation, and recurrent choroidal neovascularization at baseline were associated with better visual acuities at 3 and 6 months. Poor preoperative vision and the development of complications were associated with worse vision at 3 and 6 months. CONCLUSIONS: Limited macular translocation is a technically feasible procedure that can lead to significant visual improvement and good visual acuity in some patients presenting with subfoveal choroidal neovascularization associated with age-related macular degeneration. A randomized prospective clinical trial of this surgical technique is warranted.

Bioadhesives for intraocular use.

BACKGROUND/PURPOSE: A safe, effective adhesive could be useful in the management of retinal holes or tears and selected complicated retinal detachments, as well as for attaching a small electronic device (retinal prosthesis) to the retina. In this study, we examined nine commercially available compounds for their suitability as intraocular adhesives. METHODS: The following materials were studied: commercial fibrin sealant, autologous fibrin, Cell-Tak, three photocurable glues, and three different polyethylene glycol hydrogels. An electronic strain gauge measured the adherence forces between different glues and the retina. The stability of hydrogels at body temperature and the impermeability of the hydrogel adhesive to dextran blue were examined. Long-term biocompatibility testing of the most promising glues in terms of adhesive force, consistency, and short-term safety (hydrogels) were done in rabbits. Funduscopy, electroretinogram, and histology of the retina were performed. RESULTS: Hydrogels had 2 to 39 times more adhesive force (measured in mN) than the other glues tested. They liquefied at body temperature after 3 days to a few months. Hydrogels were impermeable to dextran blue. One type of hydrogel proved to be nontoxic to the retina. CONCLUSIONS: Hydrogels proved to be superior for intraocular use in terms of consistency, adhesiveness, stability, impermeability, and safety.

Limited macular translocation for neovascular maculopathy.

Subfoveal choroidal neovascularization presents one of the most difficult challenges to vision. No treatment option has yet solved the problem of subretinal hemorrhage and fibrovascular scarring causing permanent photoreceptor degeneration and loss. Limited macular translocation provides a surgical approach to this challenge by moving the fovea onto an adjacent area of relatively normal subretinal space and pigment epithelium in a selected group of patients. The choroidal neovascularization, thus, becomes extrafoveal or juxtafoveal and can be treated with focal laser photocoagulation. This article describes the current technique of limited macular translocation and reviews early results. The procedure offers selected patients a chance to retain useful central vision. About 40% of patients at 6 months are able to read and drive (visual acuity >20/100). Complications including retinal detachment, hemorrhage, and macular folds have decreased with experience. Limited macular translocation is a promising approach to neovascular maculopathy, but needs ongoing careful evaluation.