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Rohit R Lakhanpal

Publications and source records attributed to Rohit R Lakhanpal.

At least 19 recordsLinked to original sources
PubMed2007

Conjunctival epithelium in pars plana vitrectomy specimens.

PURPOSE: To review histopathology of vitrectomy specimens obtained during routine pars plana vitrectomy (PPV) for evidence of inadvertent introduction of conjunctival epithelium into the vitreous cavity during PPV. METHODS: Retrospective review of all vitreous specimens obtained from PPV over a 3-year period during which vitreous samples were routinely submitted from routine and diagnostic PPV. Patient charts and operative reports were reviewed, with particular attention to history of postoperative endophthalmitis, and the use of transconjunctival PPV. RESULTS: A total of 650 specimens were obtained over a 3-year period. Three specimens with conjunctival epithelium were identified. None of these cases resulted in endophthalmitis. Two of these three cases used transconjunctival techniques. In one case all three sclerotomies were made using transconjunctival techniques. CONCLUSIONS: The presence of conjunctiva in the vitreous aspirate from completely transconjunctival PPV indicates that conjunctival epithelium can be inadvertently introduced into the vitreous cavity during PPV. Although none of these cases resulted in endophthalmitis, special care to sterilize the conjunctiva before the creation of transconjunctival sclerotomies is warranted.

Aged↗
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↗
PubMed2007

Long-term retinal toxicity of intravitreal commercially available preserved triamcinolone acetonide (Kenalog) in rabbit eyes.

PURPOSE: To investigate whether intravitreal Kenalog (IVTK; Bristol Meyers Squibb Company, Princeton, NJ) produces histologic or electroretinographic changes in the rabbit retina up to 3 months after injection. METHODS: Ten Dutch-belted rabbits were injected with 4 mg/0.1 mL Kenalog in one eye and 0.1 mL physiologic salt solution (PSS) in the fellow eye. Simultaneous bilateral dark-adapted electroretinography was performed 2 weeks and 12 weeks after injection in 10 and 6 rabbits, respectively. Saturated a-wave amplitude, maximal scotopic b-wave amplitude, and individual a-wave and b-wave amplitudes of IVTK-injected and control eyes were compared at 2 and 12 weeks after injection. Light microscopy was performed on both eyes of three animals 3 months after injection. Immunohistochemistry was performed with antibodies recognizing vimentin and human alveolar macrophage (HAM)-56, markers of glial cells and macrophages, respectively. RESULTS: No significant difference was observed in the saturated a-wave or maximal scotopic b-wave amplitudes between the PSS-injected eyes and the IVTK-injected eyes at 2 weeks (P = 0.95 and P = 0.56, respectively) and 12 weeks (P = 0.82 and P = 0.17) after injection. Light microscopy and immunohistochemistry disclosed only rare macrophages in the vitreous of IVTK-injected eyes. Retinal layers, retinal pigment epithelium, and choriocapillaris in treatment and control eyes were unremarkable. CONCLUSIONS: No demonstrable electroretinographic or histologic changes occurred to suggest immediate or delayed widespread retinal toxicity of IVTK.

Animals↗
PubMed2006

Short-term course of intraocular pressure after intravitreal injection of triamcinolone acetonide.

OBJECTIVE: To describe the natural history of intraocular pressure (IOP) within the first 30 minutes after intravitreal injection of triamcinolone acetonide (TA). DESIGN: Prospective, interventional, consecutive case series. PARTICIPANTS: Thirty-eight consecutive patients who met inclusion and exclusion criteria and underwent intravitreal injection of 0.1 ml (4 mg) of TA were studied. METHODS: Intraocular pressure was measured by Goldmann applanation tonometry at baseline; immediately after injection; and at 2, 5, 10, 20, and 30 minutes after injection. MAIN OUTCOME MEASURES: Intraocular pressure measurements at baseline; immediately after intravitreal injection; and 2, 5, 10, 20, and 30 minutes after injection, and percentage of patients with IOP < or = 24 mmHg at 30 minutes. RESULTS: Patients who did not experience vitreous reflux (30/38 [78.9%]) at the site of injection had a significant initial elevation of IOP that rapidly normalized. Patients who experienced vitreous reflux (8/38 [21.1%]) at the site of injection had either no change in IOP or a small drop in IOP that rapidly normalized. The IOP measured in millimeters of mercury immediately after injection (45.9 [no reflux], 12.6 [reflux]), 2 minutes after injection (39.9 [no reflux], 13.5 [reflux]), 5 minutes after injection (33.3 [no reflux], 13.8 [reflux]), 10 minutes after injection (26.4 [no reflux], 15.1 [reflux]), and 20 minutes after injection (21.8 [no reflux], 15.0 [reflux]) showed a statistically significant difference between the 2 groups. The difference in IOP between the 2 groups was not significant at baseline or 30 minutes after injection. At 30 minutes, 90% (95% confidence interval, 85.8%-95.2%) of patients without vitreous reflux had an IOP < 24 mmHg. CONCLUSIONS: Patients undergoing intravitreal injection of TA with no vitreous reflux have a risk of short-term elevation of IOP that rapidly normalizes over 30 minutes. In patients with vitreous reflux after the injection, the IOP declines immediately after injection and rapidly normalizes over 10 minutes.

Aged↗
PubMed2006

Lens clarity after 3-port lens-sparing vitrectomy in stage 4A and 4B retinal detachments secondary to retinopathy of prematurity.

OBJECTIVE: To assess lens clarity after 3-port lens-sparing vitrectomy for stages 4A and 4B tractional retinal detachment secondary to retinopathy of prematurity. METHODS: In a retrospective, interventional, consecutive clinical case series, 108 eyes of 102 patients who underwent lens-sparing vitrectomy for stages 4A and 4B tractional retinal detachment from February 1, 1998, through January 31, 2004, were reviewed. All procedures and follow-up examinations were performed by a single surgeon. Lens clarity was assessed at the final follow-up examination. RESULTS: Of the 108 eyes reviewed, 102 (94.4%) maintained clear lenses at the final follow-up examination, which ranged from 6 to 48 months (mean, 32 months) after the procedure. Thirty-two eyes had stage 4A detachments and 76 eyes had stage 4B. CONCLUSIONS: Three-port lens-sparing vitrectomy may be performed with relatively low risk of cataract formation during the early postoperative period. Maintenance of a clear crystalline lens during the critical period of visual development may lead to better functional outcomes.

Female↗
PubMed2006

Visual outcomes after 3-port lens-sparing vitrectomy in stage 4 retinopathy of prematurity.

OBJECTIVE: To assess the visual acuity of eyes successfully treated with 3-port lens-sparing vitrectomy for stage 4 retinopathy of prematurity. METHODS: Of 102 consecutive eyes achieving at least posterior pole reattachment, 30 eyes of 26 patients were tested by Teller or Allen acuity measurements and were subsequently converted to logarithm of the minimum angle of resolution (logMAR). Visual outcomes were also examined as either favorable or unfavorable (Snellen equivalent >20/200). RESULTS: Seventy-two eyes were not tested because of either inability to perform testing (age or neurologic sequelae related to prematurity) or loss of follow-up. Of those tested, mean +/- SD logMAR visual acuity for the stage 4A and stage 4B groups was 0.51 +/- 0.09 (Snellen approximate 20/62) and 1.03 +/- 0.19 (Snellen approximate 20/200), respectively (odds ratio, 0.39; 95% confidence interval, 0.24-0.64; P = .001). Of those eyes assessed by Teller measurements, 10 of 10 stage 4A eyes and 3 (37.5%) of 8 stage 4B eyes had favorable outcomes; among eyes assessed with Allen measurements, 4 of 4 stage 4A eyes and 0 of 8 stage 4B eyes had favorable outcomes. CONCLUSIONS: The majority of eyes were not tested. Among eyes tested after successful 3-port lens-sparing vitrectomy, some eyes treated prior to macular detachment may be associated with a more favorable outcome and improved maintenance of functional visual acuity.

Female↗
PubMed2006

Lensectomy and vitrectomy with and without intravitreal triamcinolone acetonide for vascularly active stage 5 retinal detachments in retinopathy of prematurity.

PURPOSE: To determine the anatomical success rate of lensectomy and vitrectomy with and without intravitreal triamcinolone acetonide (TA) for vascularly active stage 5 tractional retinal detachments due to retinopathy of prematurity (ROP). METHODS: In a retrospective, interventional, single-surgeon, consecutive case series, the records of 21 eyes of 21 patients presenting with stage 5 retinal detachment secondary to ROP who underwent primary pars plicata vitrectomy with lensectomy from February 1998 to January 2004 were evaluated. All eyes were vascularly active at the time of surgery. Eleven eyes underwent the surgical procedure without TA (group 1), and 10 eyes received TA at the end of the procedure (group 2). The main outcome measure, retinal reattachment, was reviewed at the final follow-up visit, which ranged from 6 months to 42 months (mean, 28 months) after surgery. RESULTS: None (0/11) of the eyes in group 1 maintained attachment, while 6 (60%) of 10 eyes in group 2 maintained at least posterior pole reattachment at the final visit. None of the group 2 eyes exhibited plus disease during follow-up. None of the eyes in either group exhibited signs of increased intraocular pressure after surgery. All six eyes that maintained posterior pole reattachment were able to fix and follow light at the last follow-up visit. CONCLUSIONS: Vascularly active stage 5 ROP detachments portend a poor progress. The use of TA as a postoperative adjunct may improve the likelihood of retinal reattachment in select cases.

Birth Weight↗
PubMed2006

Anatomical success rate after primary three-port lens-sparing vitrectomy in stage 5 retinopathy of prematurity.

PURPOSE: To assess the anatomical success rate after three-port lens-sparing vitrectomy (LSV) in stage 5 (total) retinal detachments secondary to retinopathy of prematurity. METHODS: In a retrospective, interventional, single-surgeon, consecutive case series, the records of 33 eyes of 21 patients presenting with stage 5 retinal detachment secondary to retinopathy of prematurity who underwent primary three-port LSV from February 1998 to January 2004 were evaluated. Twenty-one eyes (63.6%) had open anteriorly-open posteriorly and 12 (36.4%) had open anteriorly-narrow posteriorly in terms of anatomical configuration. The main outcome measure, retinal reattachment, was reviewed at final follow-up visits, which ranged from 6 months to 48 months (mean, 32 months) after LSV. RESULTS: Fifteen eyes (45.5%) maintained attachment and 18 eyes (54.5%) remained detached at the final visit. Open anteriorly-open posteriorly configuration eyes had a statistically significant higher anatomical success rate than eyes with an open anteriorly-narrow posteriorly configuration (P<0.001). CONCLUSIONS: Three-port LSV may achieve anatomical success in stage 5 retinopathy of prematurity-related detachments. The open anteriorly-open posteriorly configuration portends a better prognosis; thus, surgery should be performed before closure of the posterior retina into a funnel configuration, if possible.

Birth Weight↗
PubMed2006

Retinal prostheses for the blind.

INTRODUCTION: Using artificial means to treat extreme vision impairment has come closer to reality during the past few decades. The goal of this research has been to create an implantable medical device that provides useful vision for those patients who are left with no alternatives. Analogous to the cochlear implants for some forms of hearing loss, these devices could restore useful vision by converting visual information into patterns of electrical stimulation that excite the remaining viable inner retinal neurons in patients with retinitis pigmentosa or age-related macular degeneration. METHODS: Data for this review were selected through a comprehensive literature search. RESULTS: Advances in microtechnology have facilitated the development of a variety of prostheses that can be implanted in the visual cortex, around the optic nerve, or in the eye. Some of these approaches have shown the promise of providing useful visual input to patients with visual impairments. CONCLUSION: While the development of various retinal prostheses have shown promise in limited clinical trials, there are distinct advantages and disadvantages for each type of prosthesis. This review will focus primarily on the Epiretinal Intraocular Retinal Prosthesis, studied by our group, but will also briefly review other modalities: the subretinal prosthesis, cortical prosthesis, and optic nerve prosthesis.

Electric Stimulation Therapy↗
PubMed2005

Macular hole in cat scratch disease.

PURPOSE: To report the development of a macular hole as a complication of cat scratch disease. DESIGN: Case report. METHODS: A 10-year-old girl was seen with unilateral neuroretinitis from serologically confirmed cat scratch disease. Twelve days later, she developed a macular hole in the involved eye. Fundus photography and optical coherence tomography (OCT) were obtained at presentation and after the development of a macular hole. RESULTS: Fundus photography and OCT on presentation revealed a nasal neurosensory detachment and multiple inflammatory foci throughout the macula, including a subfoveal lesion. Fundus photography and OCT 12 days later revealed the development of a partial posterior vitreous detachment and a full thickness macular hole. CONCLUSIONS: Macular hole should be included among posterior segment complications of cat scratch disease. In this case, the macular hole was associated with partial vitreous detachment and a preexisting subfoveal lesion, likely representing an inflammatory focus.

Antibodies, Bacterial↗
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

Anatomic success rate after 3-port lens-sparing vitrectomy in stage 4A or 4B retinopathy of prematurity.

PURPOSE: To assess the anatomic success rate after 3-port lens-sparing vitrectomy (LSV) in stage 4A and 4B tractional retinal detachments (TRDs) due to retinopathy of prematurity (ROP). DESIGN: A chart review and data evaluation of 108 eyes of 102 consecutive patients presenting with stage 4A (32 eyes) or 4B (76 eyes) TRDs that underwent primary LSV from February 1998 to January 2004 were performed. INTERVENTION: Three-port LSV was performed on all eyes by the same surgeon (ERH). MAIN OUTCOME MEASURES: Retinal reattachment status was reviewed at final follow-up visit, which ranged from 6 to 48 months (mean, 32 months) after LSV. RESULTS: Ninety-two of 108 (85.2%) eyes were reattached after a single LSV and 102 of 108 (94.4%) eyes ultimately achieved at least partial posterior pole reattachment at the final follow-up visit. All 4A eyes achieved complete reattachment and 70 of 76 (92.1%) 4B eyes achieved partial or complete reattachment. Reversal or complete arrest of dragging of the macula was noted in all eyes that maintained partial or complete reattachment (94.4%). Six (5.6%) 4B eyes remained detached despite additional vitreoretinal procedures; 4 (66.7%) of these had intraoperative retinal tears. CONCLUSIONS: Eighty-five percent of eyes with 4A and 4B TRDs secondary to ROP were completely reattached with a single 3-port LSV procedure and nearly 95% were ultimately at least partially reattached at the posterior pole by the final follow-up visit. The development of retinal tears intraoperatively portended a poor prognosis for reattachment.

Disease Progression↗
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

Effects of indocyanine green injection on the retinal surface and into the subretinal space in rabbits.

PURPOSE: To evaluate the effects of indocyanine green (ICG) injection on the retinal surface and into the subretinal space of rabbit eyes. METHODS: Twenty-two Dutch-belted rabbits underwent two-port vitrectomy followed by injection of ICG (5 mg/mL) on the retinal surface and into the subretinal space. Balanced salt solution (BSS) was also injected subretinally. The locations where ICG was delivered (both epiretinal and subretinal) were exposed to light from an endoilluminator for 7 minutes. The animals were examined at 1, 7, and 14 days after surgery. The eyes were studied by fluorescein angiography as well as light and electron microscopy. RESULTS: No damage was observed after epiretinal ICG injection, but subretinal ICG injection resulted in damage to the outer nuclear layer, photoreceptor inner and outer segments, and retinal pigment epithelium. This damage was more severe with longer follow-up. Control experiments without ICG, in which balanced salt solution was injected into the subretinal space or light was delivered on the epiretinal surface, demonstrated only damage to the photoreceptor outer segments. CONCLUSION: Subretinal delivery of ICG (5 mg/mL) in rabbits induces retinal pigment epithelium, photoreceptor inner and outer segment, and outer nuclear layer damage. These mechanisms of damage may explain the retinal pigment epithelium changes that are sometimes seen after ICG-assisted internal limiting membrane peeling in humans.

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

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↗