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Dive into the research topics where Rohit R. Lakhanpal is active.

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Featured researches published by Rohit R. Lakhanpal.


Retina-the Journal of Retinal and Vitreous Diseases | 2004

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

Mauricio Maia; Lukas Kellner; Eugene de Juan; Ricardo Luiz Smith; Michel Eid Farah; Eyal Margalit; Rohit R. Lakhanpal; Lynnea Grebe; Kah-Guan Au Eong; Mark S. Humayun

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.


Retina-the Journal of Retinal and Vitreous Diseases | 2004

Effects of intravitreal indocyanine green injection in rabbits.

Mauricio Maia; Eyal Margalit; Rohit R. Lakhanpal; Mark O. M. Tso; Rhonda Grebe; Gustavo Torres; Kah-Guan Au Eong; Michel Eid Farah; G.Y. Fujii; James D. Weiland; Eugene de Juan; Salvadori A. D’anna; Mark S. Humayun

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.


Current Opinion in Ophthalmology | 2003

Advances in the development of visual prostheses.

Rohit R. Lakhanpal; D. Yanai; James D. Weiland; G.Y. Fujii; Sean Caffey; Robert J. Greenberg; de Juan E; Mark S. Humayun

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.


Retina-the Journal of Retinal and Vitreous Diseases | 2004

Retinal pigment epithelial abnormalities after internal limiting membrane peeling guided by indocyanine green staining.

Mauricio Maia; Julia A. Haller; Dante J Pieramici; Eyal Margalit; de Juan E; Michel Eid Farah; Rohit R. Lakhanpal; Au Eong Kg; D. Guven; Mark S. Humayun

X-linked retinoschisis (XLRS) is a rare genetic disorder associated with stellate maculopathy in all affected patients and peripheral schisis in one-half of affected patients. 1 Although the pathophysiology of the disease remains largely unknown, histopathologic reports have focused on the breakdown of Müller cells and the schisis at the level of the nerve fiber layer in the periphery. 2 Optical coherence tomography is capable of high-resolution cross-sectional imaging in vivo. We used optical coherence tomography to examine the macular findings of two patients with XLRS.


Retina-the Journal of Retinal and Vitreous Diseases | 2004

Virtual vitreoretinal surgical simulator as a training tool.

Juliana V. Rossi; Verma D; G.Y. Fujii; Rohit R. Lakhanpal; Sue Lynn Wu; Mark S. Humayun; de Juan E

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.


Ophthalmic Surgery Lasers & Imaging | 2006

Optical coherence tomography of idiopathic juxtafoveolar telangiectasia.

Thomas A. Albini; Matthew S. Benz; Robert E. Coffee; Andrew C. Westfall; Rohit R. Lakhanpal; Alice R. McPherson; Eric R. Holz

BACKGROUND AND OBJECTIVE To document optical coherence tomography (OCT) findings in a series of eyes with group 2A idiopathic juxtafoveal telangiectasia. PATIENTS AND METHODS This study is a retrospective review of patient charts, OCT, fundus photography, and fluorescein angiography involving 23 eyes (12 patients). Mean retinal thickness in 9 macular areas was calculated and compared to previously published measurements from normal eyes. RESULTS OCT in 8 of 13 stage 3 eyes revealed foveal cysts without evidence of cystoid macular edema on fluorescein angiography or biomicroscopy, and 1 lamellar hole. In stage 3 eyes, mild retinal thickening was found in 7 of 9 macular areas (P < .05). CONCLUSIONS OCT commonly reveals foveal cysts in stage 3 idiopathic juxtafoveal telangiectasia. Consistent findings of associated mild macular thickening and lack of late petaloid hyperfluorescence on fluorescein angiography suggest that these cysts differ in pathophysiology from cystoid macular


Retina-the Journal of Retinal and Vitreous Diseases | 2006

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

Rohit R. Lakhanpal; Jorge A. Fortun; Brian T. Chan-Kai; Eric R. Holz

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.


Retina-the Journal of Retinal and Vitreous Diseases | 2006

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

Rohit R. Lakhanpal; Regina L. Sun; Thomas A. Albini; Eric R. Holz

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.


Retina-the Journal of Retinal and Vitreous Diseases | 2005

Transvitreal limited arteriovenous-crossing manipulation without vitrectomy for complicated branch retinal vein occlusion using 25-gauge instrumentation.

Rohit R. Lakhanpal; Michael Javaheri; Ruiz-Garcia H; de Juan E; Mark S. Humayun

Purpose: To evaluate a new technique, 25-gauge transvitreal limited arteriovenous-crossing manipulation without vitrectomy (LAM), for the treatment of branch retinal vein occlusion (BRVO) complicated by macular hemorrhage and/or macular edema recalcitrant to grid laser photocoagulation. Methods: Twelve eyes of 12 patients underwent LAM for BRVO performed by a single surgeon (M.S.H.) using the 25-gauge nitinol flexible-extendable blunt pick. The presence or absence of intraoperative reperfusion visualization, pre- and postoperative visual acuity, macular thickness as measured by optical coherence tomography, intraocular pressure, and lens status were evaluated. Results: Restoration of blood flow was noted in all patients and was based on intraoperative reestablishment of a red column of erythrocytes through the previously closed vessel. Mean visual acuity improved from 20/200 (logarithm of the minimal angle of resolution [LogMAR] ± SD, 1.00 ± 0.32) preoperatively to 20/70 (LogMAR ± SD, 0.56 ± 0.28) (P = 0.0003) at the final visit. Eleven (92%) of 12 eyes had ≥2 lines of visual improvement. Five eyes (45%) had final visual acuity of 20/50 or better. Mean macular thickness ± SD improved from 401.0 ± 73.2 to 178.7 ± 19.6 &mgr;m (P < 0.0001) at the final visit. No statistically significant difference was noted in cataract progression or intraocular pressure. Mean follow-up ± SD was 49.9 ± 19.6 weeks. All patients were observed for at least 12 weeks. Conclusion: LAM may achieve outcomes comparable with those of arteriovenous adventitial sheathotomy for complicated BRVO.


Retina-the Journal of Retinal and Vitreous Diseases | 2007

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

Michael Javaheri; G.Y. Fujii; Juliana V. Rossi; Carla Q. Panzan; D. Yanai; Rohit R. Lakhanpal; Mauricio Maia; Rahul N. Khurana; D. Guven; Eugene de Juan; Mark S. Humayun

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.

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Mark S. Humayun

University of Southern California

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Eric R. Holz

Baylor College of Medicine

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G.Y. Fujii

University of Southern California

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Michael Javaheri

University of Southern California

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Eugene de Juan

University of Southern California

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James D. Weiland

Johns Hopkins University School of Medicine

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Regina L. Sun

Baylor College of Medicine

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de Juan E

University of Southern California

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D. Yanai

University of Southern California

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