Biomedical subjects

Gildo Y Fujii

Publications and source records attributed to Gildo Y Fujii.

At least 19 recordsLinked to original sources

PubMed2007

A novel method to oxygenate intraocular irrigation fluids with an in-line oxygenator.

PURPOSE: We describe a novel method to oxygenate intraocular irrigation solutions involving an in-line oxygenator. METHODS: Either lactated Ringer (LR) solution or balanced salt solution (BSS) was oxygenated with the FE390 Stainless In-line Oxygenation Assembly (Beer, Beer, and More Beer, Concord, CA). After running a 100-mL of solution through the in-line oxygenator, oxygen saturation was measured with a dissolved oxygen meter. A control experiment involving the oxygenator without oxygen perfusion was performed. Paired t-tests were used to compare oxygen saturation changes before and after oxygenation. RESULTS: In comparison with the original BSS, there was an increase in oxygen saturation of 162 +/- 47% (n = 40; P < 0.05). Without oxygenation perfusion, there was only a 24 +/- 14% (n = 40) increase in oxygen levels in BSS, which was significantly lower than that in treated BSS (P < 0.05). In comparison with the original LR solution, there was an increase in oxygen saturation of 208 +/- 21% (n = 40; P < 0.05). Without oxygenation perfusion, there was only a 21 +/- 9% (n = 40) gain in oxygen saturation in the control LR solution, which was statistically lower as well (P < 0.05). CONCLUSION: The in-line oxygenator is an efficient tool for oxygenating BSS and LR solution. It represents a potential efficient and convenient method to oxygenate irrigating solutions for vitreoretinal surgeries.

Acetates↗

PubMed2007

Effect of oxygenated intraocular irrigation solutions on the electroretinogram after vitrectomy.

PURPOSE: To investigate the effect of oxygenated intraocular irrigating solutions on electroretinograms (ERGs) for postvitrectomy rabbits. METHODS: Eight groups of five rabbits each underwent pars plana vitrectomy on the right eye; the left eye of each rabbit served as control. The intraocular irrigating solutions were balanced salt solution (BSS), BSS-plus, BSS + oxygen (BSS + O2), BSS-plus + O2, and combinations of each with the addition of endoillumination (L). All animals were evaluated by single-flash scotopic electroretinography on the operated and nonoperated eyes before surgery and at 1 hour, 1 day, 1 week, and 1 month after surgery by an unmasked observer. The main outcome measures were dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios. The results for the different groups were compared by analysis of variance. RESULTS: Mean dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios +/- SD for BSS-plus and BSS-plus + O2 before surgery and 1 hour, 1 day, 1 week, and 1 month after surgery were 1.01 +/- 0.09, 0.50 +/- 0.11, 0.95 +/- 0.11, 0.97 +/- 0.11, and 0.99 +/- 0.08 and 0.98 +/- 0.08, 0.59 +/- 0.10, 0.92 +/- 0.06, 0.97 +/- 0.08, and 0.97 +/- 0.10, respectively. At both 1 hour and 1 day after surgery, rabbits treated with BSS-plus + O2 had an earlier b-wave return to baseline findings, but the differences were not statistically significant (P > 0.05). Mean dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios +/- SD for BSS and BSS + O2 before surgery and 1 hour, 1 day, 1 week, and 1 month after surgery were 1.02 +/- 0.10, 0.47 +/- 0.09, 0.77 +/- 0.07, 0.89 +/- 0.07, and 0.89 +/- 0.07 and 1.02 +/- 0.06, 0.62 +/- 0.16, 0.94 +/- 0.09, 0.97 +/- 0.08, and 0.96 +/- 0.06, respectively. One hour and 1 day after surgery, ERG readings for rabbits treated with BSS + O2 exhibited a statistically significantly earlier return of ERG voltage to baseline values compared with both BSS and BSS + L (P = 0.05 and P = 0.02, respectively). One day after surgery, rabbits treated with BSS alone had the lowest ERG ratios. One week and 1 month after surgery, for all solutions tested other than BSS, ERG values were within normal limits. CONCLUSION: The use of oxygenated solutions appears to affect ERG readings after pars plana vitrectomy. Further studies to evaluate the role of oxygenated solutions in different vitreoretinal surgical procedures are warranted.

Acetates↗

PubMed2005

Fabrication, implantation, elution, and retrieval of a steroid-loaded polycaprolactone subretinal implant.

A subretinal drug delivery system was developed to overcome the limitations of current treatments for retinal disease. A rod-shaped implant was made by embedding the corticosteroid triamcinolone acetonide within a biodegradable polycaprolactone polymer matrix. The implant was fabricated by homogeneously mixing the polymer and drug in solvent. The mixture was then dried, melted, and extruded, and the prepared solid form was drawn into a filament. The rods were mechanically sectioned to a length of 2 mm with a diameter of up to 320 microm. The rods were successfully implanted into the subretinal space of six rabbits. No complications were observed during the 4-week follow-up period. Initial observations of the implantation and elution characteristics revealed that polycaprolactone is well tolerated by the retinal tissue and that the implant can elute steroid for a period of at least 4 weeks without eliciting inflammatory response or complications. In vitro drug elution rates of different polymer to drug ratios and geometries into a balanced salt solution/bovine serum albumin (1%) solution showed an early rapid-release phase and late first-order phase. Histology and device retrieval after implantation revealed minimal encapsulation and good preservation of cellular morphology during the follow-up period and a more fibrous polymer microstructure of the implant.

Absorbable Implants↗

PubMed2005

Outcomes of 140 consecutive cases of 25-gauge transconjunctival surgery for posterior segment disease.

PURPOSE: To evaluate the safety and efficacy of 25-gauge instrumentation for a variety of vitreoretinal conditions on previously nonvitrectomized eyes. DESIGN: Single-center, retrospective, interventional case series. PARTICIPANTS: One-hundred forty eyes of 140 patients were evaluated at the Doheny Retina Institute from July 2002 to July 2003. INTERVENTION: All patients underwent surgical procedures using the Millennium 25-gauge Transconjunctival Standard Vitrectomy system. Twenty eyes (14.3%) underwent procedures without vitrectomy. MAIN OUTCOME MEASURES: Postoperative visual acuity (VA), intraocular pressure, surgical time, postoperative inflammation, complications, and number of sutured sites. RESULTS: No intraoperative complications were noted. No cases required conversion to 20-gauge machines. Ten cases (7.1%) involved single-site sclerotomy suture placement due to bleb formation at the conclusion of the procedure, but 5 of these entry sites were enlarged to facilitate larger instrumentation for tissue manipulation. Median VA improved from 20/250 (logarithm of the minimum angle of resolution, 1.08+/-0.47) preoperatively to 20/60 (0.47+/-0.30) (P<0.0001) at final visit. Mean follow-up was 33.8+/-9.7 weeks, and all eyes were observed for a minimum of 12 weeks. Mean total surgical time was 17.4+/-6.9 minutes. Intraocular pressures remained stable throughout the postoperative course. Five eyes (3.8%) presented on day 1 with shallow choroidal detachments, but all resolved by day 7, and none required volume infusion during the postoperative period. All but one of these cases was within the first 50 procedures performed. No detectable inflammation was noted in any eyes by 4 weeks postoperatively. No case of retinal detachment or endophthalmitis was recorded. CONCLUSIONS: Transconjunctival surgery using 25-gauge instrumentation may hasten postoperative recovery by decreasing overall surgical time and postoperative inflammation. Procedures requiring minimal intraocular manipulation did not require sutures and, thus, may be better suited for this surgical modality.

Aged↗

PubMed2005

Rapid recurrence of geographic atrophy after full macular translocation for nonexudative age-related macular degeneration.

OBJECTIVE: To report the recurrence of geographic atrophy (GA) in a patient with nonexudative age-related macular degeneration (AMD) after full macular translocation. DESIGN: Observational case report. METHODS: Review of the clinical, photographic, and angiographic records of a patient with GA who underwent full macular translocation. MAIN OUTCOME MEASURES: Progression of GA. RESULTS: A 73-year-old man with GA secondary to nonexudative AMD underwent a macular translocation with 360 peripheral retinectomy (MT 360) in his left eye. On postoperative month 4, fundus photography showed subtle alterations of the pigment underneath the translocated foveal region. On postoperative month 9, the visual acuity worsened to preoperative levels and there was frank retinal pigment epithelium atrophy involving the new macular region. CONCLUSIONS: The rapid recurrence and development of GA in the translocated fovea after MT 360 raise new questions regarding the pathogenesis of GA. They also raise concerns regarding the use of MT 360 in the management of nonexudative AMD.

Aged↗

PubMed2004

Retinal vein cannulation with prolonged infusion of tissue plasminogen activator (t-PA) for the treatment of experimental retinal vein occlusion in dogs.

PURPOSE: To evaluate the feasibility, safety, and efficacy of local thrombolytic agents directly injected into occluded retinal veins in an experimental animal model. DESIGN: Experimental animal study. METHODS: This experimental study was performed in two phases. In phase 1, 15 enucleated porcine eyes and 8 in vivo canine eyes were used for the development of the instrumentation and surgical technique required for retinal vein cannulation with prolonged intravascular infusion. In phase 2 of this study, experimental branch retinal vein occlusion was photo-chemically created using an intravenous injection of rose bengal followed by diode laser photocoagulation in eight eyes of eight dogs. Four eyes were treated by retinal vein cannulation and an injection of tissue plasminogen activator (t-PA) using a specifically designed microcatheter, while the remaining four eyes were untreated (control group). The total amount of t-PA injected intravenously ranged from 400 to 1000 mug, infused over a period ranging from 25 to 45 minutes with a mean pressure of 40 psi, resulting in a mean injection flow rate of 0.05 ml/min. The dogs underwent clinical examination, fluorescein angiography, and histologic examination. Main outcome measures were: Achievement of prolonged intravascular infusion of t-PA, changes in fundus appearance, fluorescein angiography, and histology. RESULTS: A microcatheter instrument and a surgical technique for retinal vein cannulation with prolonged intravascular infusion were developed. Cannulation and t-PA infusion for a period of at least 30 minutes was achieved in all four treated eyes with experimental branch retinal vein occlusion. No complications were recorded in all treated eyes. One week and 1 month postoperatively, treated eyes exhibited marked decreases in retinal hemorrhages, retinal vein dilation, and tortuosity, whereas nontreated eyes exhibited persistence of these findings. Fluorescein angiography demonstrated improved circulatory flow in treated relative to nontreated eyes. Histologic analysis confirmed the presence of thrombi in nontreated eyes only. CONCLUSIONS: Retinal vein cannulation with prolonged intravascular injection of t-PA is feasible and safe, and this may offer a new treatment option for retinal vein occlusion.

Animals↗

PubMed2004

Limited macular translocation: a clinicopathologic case report.

OBJECTIVE: To illustrate the histopathologic findings in a patient who underwent limited macular translocation. DESIGN: Observational case report. METHODS: The patient underwent limited macular translocation for subfoveal choroidal neovascularization resulting from age-related macular degeneration. Thirty-one months after surgery, the patient had died and both eyes were obtained at autopsy. Serial sections through both maculas were obtained. Immunohistochemistry of the foveas with C10C10 and hCAR/LUMIf antibodies for rods and cones, respectively, was performed. MAIN OUTCOME MEASURES: Histopathologic changes in the operated eye as compared with the fellow eye. RESULTS: There was no morphologic difference in the subfoveal retinal pigment epithelium, Bruch's membrane, or choriocapillaris, but there was a decreased cone density in the translocated fovea as compared with the fellow eye. CONCLUSIONS: In this patient, the fovea was translocated without causing apparent change in the underlying retinal pigment epithelium, Bruch's membrane, or choriocapillaris. Although there may be some photoreceptor loss, the excellent visual recovery suggests that the retinal pigment epithelium underlying the translocated fovea is functionally adequate.

Aged↗

PubMed2004

Macular translocation in patients with recurrent subfoveal choroidal neovascularization after laser photocoagulation for nonsubfoveal choroidal neovascularization.

PURPOSE: To report visual outcomes and to examine surgical factors affecting outcomes in patients undergoing macular translocation for recurrent subfoveal choroidal neovascularization after laser photocoagulation for nonsubfoveal choroidal neovascularization. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: A consecutive series of 31 eyes of 29 patients who underwent macular translocation for recurrent subfoveal choroidal neovascularization after laser photocoagulation for nonsubfoveal choroidal neovascularization. INTERVENTION: Inferior macular translocation with punctate retinotomy performed by a single surgeon. OUTCOME MEASURES: Surgical and visual outcomes at 3 and 6 months after surgery and complications data are reported. Associations between surgical factors and visual outcomes were analyzed statistically. RESULTS: Effective translocation was achieved in 77.4% of eyes. At 6 months, 54% of eyes achieved visual acuity (VA) better than 20/100, and 46% of eyes gained the equivalent of > or =2 Early Treatment Diabetic Retinopathy Study lines of vision. No association between size of recurrent choroidal neovascularization and visual outcome was identified. Eyes with a larger scar size experienced lower VA at 3 and 6 months, but scar size was not associated with change in VA at 3 and 6 months. Subretinal dissection during surgery to detach the macula was required in 8 of 31 eyes and was associated with a significantly increased incidence of peripheral retinal breaks. However, there was no difference in either VA or change in VA in eyes with and without subretinal dissection. Retinal detachment (RD) occurred in 6 of 31 eyes. No significant difference in the RD rate was observed between groups with or without subretinal dissection (P = 0.30). CONCLUSION: Our pilot data suggest that macular translocation can result in favorable surgical outcomes in patients with recurrent subfoveal choroidal neovascularization after laser photocoagulation for nonsubfoveal choroidal neovascularization. Use of subretinal dissection intraoperatively in these patients does not seem to affect visual outcome adversely, but may be associated with increased risk of peripheral retinal breaks.

Adult↗

PubMed2004

Effects of intravitreal indocyanine green injection in rabbits.

PURPOSE: To report the clinical, electrophysiologic, and histologic findings of different concentrations of indocyanine green (ICG) injected into the vitreous cavity of rabbit eyes. METHODS: Forty-two rabbits underwent intravitreal injection of 0.1 mL of ICG in three different concentrations: 0.5 mg/mL (250 mOsm), 5 mg/mL (270 mOsm), and 25 mg/mL (170 mOsm). Fellow eyes were injected with 0.1 mL of balanced salt solution. Biomicroscopy, ophthalmoscopy, electroretinography, fluorescein angiography, and histologic evaluation were performed. RESULTS: Eyes injected with 0.5 mg/mL of ICG showed b-wave latency delay on the first day after injection. Eyes injected with 5 mg/mL of ICG showed b-wave latency delay and decreased b-wave amplitude on the first and seventh days after injection; delayed a-wave latency on the first day after injection was also observed. Eyes injected with 25 mg/mL of ICG showed b- and a-wave amplitude and latency abnormalities during the entire follow-up. Direct correlation of increasing retinal edema proportional to the progressively increasing ICG concentrations was shown on histologic evaluation. CONCLUSION: Intravitreal ICG injection in rabbit eyes may impair retinal function and morphology proportional to the progressively increasing ICG dosages.

Animals↗

PubMed2004

Virtual vitreoretinal surgical simulator as a training tool.

OBJECTIVE: To demonstrate the feasibility and potential applicability of a virtual reality simulator for vitreoretinal surgery as a training and/or assessment tool. METHODS: The subjects of this study included medical students, ophthalmologic residents, and trained vitreoretinal surgeons. There were three study groups. Group I comprised 22 subjects who performed a navigation task. The time to complete the task was recorded. The relationship between the completion time, experience, and stereopsis was evaluated. Group II included 6 subjects who consecutively performed the navigation task to evaluate their learning curve. Group III included 16 subjects who performed the membrane peeling task. The number of retinal contacts and the completion time were recorded. The relationship between experience and stereopsis with the number of contacts and the completion time were evaluated. RESULTS: The average completion time in Group I for students, residents, and trained surgeons was 121.6, 92.5, and 70.6 seconds. There was a significant difference between students and trained surgeons (P = 0.004). In Group II, there was a significant decrease in the completion time with training (P = 0.001). In Group III, the average completion time for students, residents, and trained surgeons was 197, 144, and 118.2 seconds; the respective number of retinal contacts was 14, 8, and 3. There was a significant difference between students and residents (P = 0.05) and between residents and trained surgeons (P = 0.003) for the average completion time in Group III. There was a significant difference between students and trained surgeons (P = 0.003) for the number of contacts per average time and between students and residents (P = 0.05). There was a significant inverse correlation between stereopsis vision score and completion time in Group I and number of contacts per average time (P = 0.0004 and P = 0.01, respectively). CONCLUSIONS: This study demonstrates potential applications of a vitreoretinal surgical simulator as a training and skills assessment tool for novice, inexperienced, and trained surgeons. A simulator can be used to teach specific techniques and train surgeons.

Adult↗

PubMed2003

Limited macular translocation for the management of subfoveal choroidal neovascularization after photodynamic therapy.

PURPOSE: To report our initial experience of limited macular translocation in patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration following photodynamic therapy with verteporfin. DESIGN: Interventional case series. METHODS: Retrospective review of four eyes of four consecutive patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration who underwent effective limited macular translocation following photodynamic therapy. The mean logarithm of minimal angle of resolution preoperative best-corrected visual acuity was 20/190 (range, 20/150 to 20/200), and in all eyes the visual acuity was 20/150 or worse. The major outcome measures were postoperative visual acuity and complications related to the surgery. RESULTS: The mean postoperative follow-up was 6.75 months (range, 6-8 months). Postoperative best-corrected visual acuity improved by 2 or more Snellen lines of visual acuity in three of four eyes (75%) and remained within 1 line in one of four eyes (25%). The mean postoperative best-corrected visual acuity was 20/100 (range, 20/40 to 20/150), and in two of the four eyes (50%) the visual acuity achieved was 20/100 or better. No complication was observed. CONCLUSIONS: Limited macular translocation may be a viable option in patients who have previously undergone photodynamic therapy.

Aged↗

PubMed2003

Characteristics of visual loss by scanning laser ophthalmoscope microperimetry in eyes with subfoveal choroidal neovascularization secondary to age-related macular degeneration.

PURPOSE: To evaluate the effects of subfoveal choroidal neovascularization secondary to age-related macular degeneration on functional parameters obtained by scanning laser ophthalmoscope microperimetry. DESIGN: Retrospective observational case series and cross-sectional study. METHODS: At the Doheny Retina Institute and Wilmer Eye Institute a consecutive series of 179 eyes of 175 patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration was studied. The onset of visual symptoms, best-corrected visual acuity, fluorescein angiography, evaluation of fundus microperimetry and fixation pattern using the Rodenstock scanning laser ophthalmoscope were obtained for each patient. The main outcome measures were central retinal sensitivity and fixation pattern (fixation location and fixation stability) in eyes with subfoveal choroidal neovascularization and their relationship to the length of disease, type and characteristics of choroidal neovascularization, and visual acuity. RESULTS: Of 179 eyes, 135 (75%) had central fixation, 27 (15%) had poor central fixation, and 17 (9%) had predominantly eccentric fixation. Seventy-six eyes (42%) had stable fixation, 70 eyes (39%) had relatively unstable fixation, and 33 eyes (18%) had unstable fixation. In 50 eyes (28%) a dense central scotoma was noted. Eighty-nine of 100 eyes (89%) with length of symptoms of less than 3 months had predominantly central fixation and 58 (58%) had stable fixation; 14 of 34 eyes (41%) with length of symptoms of more than 6 months had predominantly central fixation, and 5 eyes (15%) had stable fixation. In 15 eyes of patients who elected not to receive treatment, successive scanning laser ophthalmoscope microperimetry were obtained over time (follow-up of 18 months after onset of symptoms). Three months or less after the onset of symptoms, 13 eyes (87.7%) had predominantly central fixation and 9 eyes (60%) had stable fixation. More than 3 months and 6 months or less after the onset of symptoms, 10 eyes (66.7%) had predominantly central fixation and 7 eyes (46.7%) had stable fixation. This trend was further demonstrated in eyes more than 6 months after the onset of symptoms. CONCLUSIONS: We conclude that the sequence of events leading to visual function deterioration appears to involve an initial mild decrease in central retinal sensitivity and visual acuity followed by progressive fixation instability and, ultimately, development of an absolute central scotoma with totally eccentric fixation. Increased length of disease is associated with worse fixation pattern and retinal sensitivity deterioration as assessed by scanning laser ophthalmoscope microperimetry. A better understanding of the characteristics of visual loss assessed by fixation pattern evaluation and microperimetry in age-related macular degeneration may help optimize timing, patient selection, and treatment options in eyes with this condition.

Aged↗

PubMed2003

Visual perception in a blind subject with a chronic microelectronic retinal prosthesis.

A retinal prosthesis was permanently implanted in the eye of a completely blind test subject. This report details the results from the first 10 weeks of testing with the implant subject. The implanted device included an extraocular case to hold electronics, an intraocular electrode array (platinum disks, 4 x 4 arrangement) designed to interface with the retina, and a cable to connect the electronics case to the electrode array. The subject was able to see perceptions of light (spots) on all 16 electrodes of the array. In addition, the subject was able to use a camera to detect the presence or absence of ambient light, to detect motion, and to recognize simple shapes.

Aged↗

PubMed2003

Force comparison of air currents produced by a standard and modified infusion cannula.

OBJECTIVE: To develop and characterize an infusion cannula that reduces the intraocular jet forces created during fluid-air exchange. METHODS: A new infusion cannula was manufactured by adding a baffle 1.0 mm perpendicular to the distal opening of a 20-gauge infusion. The forces generated by the modified and standard cannulas were measured at a constant air infusion pressure of 50 mmHg by using a force sensor coupled to a schematic eye with eight radial positions from 0 degrees to 180 degrees along the circumference. Five different orientations relative to the baffle support of the modified cannula were evaluated at each position to assess the turbulent flow. RESULTS: The standard cannula produced a maximum force of 0.14 mmHg at 180 degrees from the sensor. The modified cannula generated a maximum pressure of 0.017 mmHg at 67.5 degrees from the sensor. Overall, the force from the modified cannula was an order of magnitude less than the standard infusion cannula (P < 0.01). CONCLUSIONS: The modifications of the new infusion cannula are passive with respect to its surgical performance. However, the additional baffle transforms laminar air currents into turbulent ones and allows dispersion of the jet forces, which should reduce barotrauma and desiccation of the retina during fluid-air exchange.

Biomechanical Phenomena↗

PubMed2003

Angiographic characteristics in patients undergoing macular translocation for subfoveal choroidal neovascularization secondary to age-related macular degeneration.

PURPOSE: To review in a standardized fashion pre- and postoperative fluorescein angiographic characteristics in patients undergoing limited macular translocation (LMT) with scleral imbrication to treat subfoveal choroidal neovascularization (SFCNV) secondary to age-related macular degeneration (AMD). The current study was undertaken to assess any potential effects of the translocation procedure on altering the angiographic characteristics of SFCNV before laser photocoagulation. METHODS: A consecutive series of patients undergoing LMT for AMD was identified retrospectively. The pre- and postoperative fluorescein angiograms were reviewed in a masked fashion. Angiographic characteristics evaluated included pre- and postoperative lesion components, stability of lesion, and the amount of retinal translocation obtained. RESULTS: Eighty-eight patients (90 eyes) had angiograms of adequate quality to permit evaluation. Time between the preoperative and the prelaser angiogram ranged from 2 to 84 days (median 7.5 days). Neovascular complexes remained unchanged or decreased in size in 79% of patients. There was no statistically significant difference in lesion size between the pre- and postoperative periods (P = 0.34). Retinal movement ranged from 160 microm to 3,320 microm (median 960 microm), with 61% of cases undergoing effective translocation (i.e., the fovea was moved away from the neovascular complex). None of the lesion components or demographic factors evaluated affected the amount of translocation obtained. Larger lesions were more likely to remain subfoveal following translocation (P = 0.004). CONCLUSION: The size and lesion characteristics appear relatively stable following translocation. Amount of retinal movement is not associated with angiographic lesion characteristics. Only size was associated with achievement of desired translocation in the final model, with large lesions being less likely to achieve desired translocation. In our study group, the amount of retinal translocation was variable with 61% of cases undergoing effective translocation.

Adult↗

PubMed2003

Advances in the development of visual prostheses.

Visual prostheses are based on neuronal electrical stimulation at different locations along the visual pathway (ie, cortical, optic nerve, epiretinal, subretinal). In terms of retinal prostheses, advances in microtechnology have allowed for the development of sophisticated, high-density integrated circuit devices that may be implanted either in the subretinal or epiretinal space. Analogous to the cochlear implants for some forms of deafness, these devices could restore useful vision by converting visual information into patterns of electrical stimulation that would excite the remaining spared inner retinal neurons in patients with diseases such as retinitis pigmentosa and age-related macular degeneration. The different types of implants and recent results are discussed, but special emphasis is given to retinal implants.

Electric Stimulation↗

PubMed2003

The value of preoperative tests in the selection of blind patients for a permanent microelectronic implant.

PURPOSE: To determine the best candidates (ie, those requiring lowest current levels delivered to the retina to elicit visual perceptions) for long-term implantation of a microelectronic retinal implant through a series of preoperative visual, psychophysical, and electrophysiological tests. METHODS: This study protocol was granted an investigational device exemption by the Food and Drug Administration and was approved by the institutional review board at the University of Southern California. After informed consent was obtained, all subjects underwent the following preoperative tests: dark-adapted bright flash and 30-Hz flicker electroretinograms, electrical evoked responses (EERs) using a Burian-Allen corneal electrode to stimulate the globe, and psychophysical tests to evaluate the light and electrically elicited visual perceptions. Intraocular stimulation (IOS) of the retina was performed by an array of electrodes positioned on the internal limiting lamina. RESULTS: Lower vision correlated with less sensitive psychophysical responses (P<.0001). Lower vision and less sensitive psychophysical tests correlated with higher EER values for stimulus pulse widths of 2 ms (P<.0008) and 4 ms (P<.0002). Lower IOS currents correlated with more sensitive psychophysical responses (P<.02) and lower EER values at 4 ms (P<.04). CONCLUSIONS: Preoperative testing, especially psychophysical and electrophysiological tests to assess light and electrically driven visual responses, can help in evaluating patients for suitability for receiving a permanent microelectronic retinal implant. Further study is warranted.

Blindness↗

PubMed2002

Inferior limited macular translocation for subfoveal choroidal neovascularization secondary to age-related macular degeneration: 1-year visual outcome and recurrence report.

PURPOSE: To report the 1-year visual outcomes and incidence of persistent and recurrent choroidal neovascularization (CNV) after limited macular translocation (LMT) for subfoveal CNV in patients with age-related macular degeneration (ARMD). DESIGN: Interventional case series. METHODS: Retrospective review of 102 consecutive eyes of 101 patients that had the inferior limited macular translocation procedure for subfoveal choroidal neovascularization secondary to ARMD. The outcome measures were visual acuity at 12 months after surgery, change in visual acuity from baseline, the proportion of eyes with moderate (3 or more lines) or severe (6 or more lines) visual acuity loss, and cumulative incidence of persistent or recurrent CNV and its impact on visual acuity. Cumulative incidence was estimated using Kaplan-Meier survival analysis methods. Association between persistence and recurrence of CNV and the Snellen visual acuity recorded at each follow-up visit was evaluated using the Wilcoxon rank-sum test. RESULTS: Eighty-six (84.3%) of 102 eyes completed the 1-year follow-up. By 12 months postoperatively, 35 (40.7%) of the 86 eyes achieved visual acuity of 20/100 or better while 34 (39.5%) of the 86 eyes experienced 2 or more Snellen lines of visual improvement. In the 52 eyes with effective translocation and complete laser photocoagulation of the CNV complex with sparing of the sensory fovea, the estimated incidence of recurrence was 34.6% at 12 months (95% confidence interval of 21%-48%). Sixty-five percent of the recurrences were subfoveal and caused a decrease in visual acuity. There was a trend toward worse median change in visual acuity in eyes with persistent or recurrent CNV. CONCLUSIONS: Limited macular translocation for the treatment of subfoveal CNV secondary to ARMD is associated with improvement in visual acuity in approximately 39.5% of eyes and enables complete laser photocoagulation of the neovascular complex with sparing of the sensory macula in approximately 60.4% of eyes that complete 1 year follow-up. Persistence and recurrence of CNV are common after LMT and are important causes of vision loss. Further studies are warranted to more precisely evaluate the risks and benefits of LMT in ARMD.

Choroidal Neovascularization↗