Toxicity of indocyanine green injected into the subretinal space: subretinal toxicity of indocyanine green

Closure of recalcitrant macular hole after choroidal neovascularization

Purpose:

To report the closure of a recalcitrant macular hole (MH) following the development of choroidal neovascularization.

Methods:

A 67-year-old female patient in this case report was diagnosed with a MH and operated twice, but anatomical closure of MH could not be achieved. The patient was followed up without further treatment, as she rejected any additional procedure.

Results:

Six months later, a lesion consistent with choroidal neovascularization appeared in the central macula, and the recalcitrant MH closed spontaneously. The MH defect remained closed in the following years.

Conclusion:

Besides being a new example of the presence of choroidal neovascularization after MH surgery, the most important aspect of this case report is to report the closure of a recalcitrant MH following the development of choroidal neovascularization.

Safety and efficacy of brilliant blue g250 (BBG) for lens capsular staining: a phase III physician-initiated multicenter clinical trial

PURPOSE

To evaluate the safety and efficacy of BBG (Brilliant Blue G250) for lens capsular staining during cataract surgery with continuous curvilinear capsulorhexis.

STUDY DESIGN

Prospective clinical study.

METHODS

This clinical trial enrolled 30 eyes of 30 patients who underwent cataract surgery with BBG (0.25 mg/mL Brilliant Blue G250) for capsular staining. Visualization of the lens capsule and the ease of capsulorhexis with BBG staining were evaluated in five grades (grade 0 to 4) by the Independent Data Monitoring Committee and the surgeons. The safety of BBG was also evaluated in terms of ocular and systemic tolerance for 7 days after surgery.

RESULTS

The use of BBG improved visualization of the lens capsule and complete capsulorhexis was performed in all patients. The major endpoint (Independent Data Monitoring Committee evaluation) showed that use of BBG improved visualization of the lens capsule and the ease of capsulorhexis (grades 2 to 4); the committee's grading results were similar to those of the surgeons. Frequent complications observed in more than two eyes were conjunctival injection, corneal edema and intraocular pressure elevation. No severe complications were observed in ocular and systemic evaluations.

CONCLUSION

BBG staining contributed to improved visualization of the lens capsule and aided in the completion of capsulorhexis during cataract surgery. The use of BBG for capsular staining also exhibited favorable safety results.

Efficacy of the Inverted Internal Limiting Membrane Flap Technique with Perfluorocarbon Liquid-Mediated Selective Staining for Large Macular Hole Repair

PURPOSE

The aim of the present study was to evaluate the efficacy of the inverted internal limiting membrane (ILM) flap technique that involved the use of a perfluorocarbon liquid (PFCL) bubble for the selective prevention of indocyanine green (ICG) staining of the parts of the inverted flap in contact with the retinal pigment epithelium for large macular hole (MH) closure.

MATERIALS AND METHODS

This retrospective, interventional, comparative study included 26 patients with idiopathic large MHs (minimum diameter, > 400 µm) who underwent vitrectomy using the inverted ILM flap technique with conventional ILM staining with ICG (n = 14, Group 1) or PFCL-mediated selective ILM staining with ICG (n = 12, Group 2). The hole closure rate, best-corrected visual acuity (BCVA), and optical coherence tomography findings were analyzed at baseline and 1, 3, and 6 months after surgery in both groups.

RESULTS

Hole closure was achieved in all the eyes. BCVA significantly improved after surgery in both groups (p < 0.001 for both groups), although Group 2 exhibited significantly better values at 3 and 6 months after surgery (p = 0.008 and 0.001 at 3 and 6 months, respectively). The sizes of ellipsoid zone defect significantly decreased after surgery in both groups (p < 0.001 relative to the baseline width in both groups), and it was significantly smaller in Group 2 than in Group 1 at 3 (p = 0.006) and 6 (p = 0.001) months after surgery.

CONCLUSIONS

The findings of this study suggest that recovery of the photoreceptor layers and, consequently, the postoperative VA are better with the inverted ILM flap technique employing PFCL-mediated selective ILM staining with ICG than with the technique employing conventional ILM staining with ICG methods for patients with large MHs.

The intraocular staining potential of anthocyanins and their retinal biocompatibility: a preclinical study

PURPOSE

To perform preclinical studies to determine the efficacy and safety of anthocyanins as stains for the internal limiting membrane (ILM) of the eye.

MATERIALS AND METHODS

Cyanidin (Cya), delphinidin (Del), luteolinidin (Lut), peonidin (Peo) and pelargonidin (Pel) were evaluated. These natural dyes were used to stain the lens capsule and ILM of pig eyes. The effects of these dyes on retinal cell viability was determined using a water-soluble tetrazolium salt assay, and oxidative stress was measured in vitro. Histopathology, in situ TUNEL labelling, transmission electronic microscopy (TEM), and electroretinography (ERG) were performed on rats following the intravitreal and subretinal injection of the neuroprotective dyes.

RESULTS

All anthocyanins stained the lens capsule and ILM of the pigs at a concentration of 1 mg/ml. Del, Lut and Peo were non-toxic and produced survival rates in the ARPE19 and RGC5 cells that were similar to those in control cells. We treated eyes with H₂O₂ and three dyes (Del, Lut, and Peo) to explore the possible neuroprotective effects and observed significantly higher survival rates in the ARPE19 cells treated with Del, Lut or Peo and the RGC5 cells treated with Lut or Peo than those in the control cells. Three dyes were intravitreally and subretinally injected into rats in vivo, and the histology showed mildly disorganized retinal cell layers. TUNEL staining and TEM examinations did not reveal additional toxic effects. Rat ERGs were not altered after intravitreal injections.

CONCLUSIONS

This preclinical study, Del, Lut, and Peo show potential as staining agents and warrant further investigation as vital dyes.

Visual Acuity after Vitrectomy and Epiretinal Membrane Peeling with or without Premacular Indocyanine Green Injection

PURPOSE

To compare postoperative visual acuity of eyes operated for an epiretinal membrane (ERM), with or without intraoperative intraocular indocyanine green (ICG) injection.

METHODS

Retrospective study of 75 pseudophakic eyes with epiretinal membrane operated by vitrectomy-peeling. In 20 cases operated in 2001 and 2002 (Group 1), ICG diluted in 5% glucose solution was injected intraoperatively into the vitreous. In another group of 55 cases operated between 1996 and 1999 (Group 2), ICG was not used.

RESULTS

The mean visual acuity was 0.32(+1) and 0.32(+2) preoperatively, 0.4(+2) and 0.5 at 1 month, and 0.63 and 0.63(+2) on the final examination in Groups 1 and 2, respectively. Visual acuities were not significantly different between the two groups.

CONCLUSIONS

Premacular injection of ICG during vitrectomy to facilitate epiretinal membrane peeling did not appear to compromise postoperative improvement of visual acuity. However, its use is questioned since it did not yield better postoperative results and because potential toxic adverse reactions could not be excluded by this study.

LONG-TERM OUTCOMES OF 23-GAUGE PARS PLANA VITRECTOMY WITH INTERNAL LIMITING MEMBRANE PEELING AND GAS TAMPONADE FOR MYOPIC TRACTION MACULOPATHY: A Prospective Study

PURPOSE

To investigate the long-term safety and efficacy of microincisional 23-gauge pars plana vitrectomy with internal limiting membrane (ILM) peeling and gas tamponade in the treatment of myopic traction maculopathy.

METHODS

A prospective nonrandomized multicenter study was designed. Patients with myopic traction maculopathy without macular hole and retinal detachment were included in the study between January 2009 and May 2012. All patients underwent microincisional 23-gauge pars plana vitrectomy with ILM peeling and 12% C3F8 gas tamponade. In all cases, brilliant blue G staining of the ILM was performed. All patients were prospectively evaluated. The evolution of best-corrected visual acuity (BCVA) and macular thickness were recorded.

RESULTS

Myopic traction maculopathy resolved in 28 of the 30 patients (93%) included. Mean follow-up was 33.8 ± 13 months (range, 24-60 months). Mean time of myopic traction maculopathy resolution after surgery was 2.65 ± 1.4 months. At 1 month after surgery, one patient developed a macular hole and another one a rhegmatogenous retinal detachment. After 2 years, another patient developed a retinal detachment. Statistically significant improvements in macular thickness compared with baseline were found at all follow-up visits (P < 0.001, Student's t-test). At final visit, BCVA improved significantly compared with baseline (P = 0.044, Wilcoxon's test). However, a statistically significant improvement in visual acuity was achieved only in eyes with a preoperative Snellen visual acuity ≥ 20/63 (P = 0.027). In contrast, the final BCVA of eyes with worse preoperative visual acuity (<20/63) did not improve significantly (P = 0.41, Wilcoxon's test).

CONCLUSION

Microincisional 23-gauge pars plana vitrectomy with ILM peeling and gas tamponade is effective in the treatment of myopic traction maculopathy, with low postoperative complications. Globally, both BCVA and macular thickness improved significantly during the follow-up period. However, greater visual acuity improvements were only seen in eyes with preoperative BCVA equal to or better than 20/63 Snellen equivalent. Some concerns remain about the risk of macular hole formation after ILM peeling. Further studies are necessary to investigate this issue.

Comparison of the Effectiveness of Pars Plana Vitrectomy with and without Internal Limiting Membrane Peeling for Idiopathic Retinal Membrane Removal: A Meta-Analysis

We conducted a meta-analysis of published retrospective studies and compared the effectiveness of pars plana vitrectomy with and without internal limiting membrane (ILM) peeling for idiopathic epiretinal membrane (IERM). The results revealed that patients in the IERM+ILM peeling group had better BCVA after surgery within 12 months than those in IERM peeling group. But patients in the IERM peeling group showed better BCVA in the 18th month. More retrospective studies or randomized controlled trials are required to investigate and compare the long-term effect of IERM removal with and without ILM peeling.

Clinical outcomes of double staining and additional ILM peeling during ERM surgery

PURPOSE

To assess the clinical outcomes in idiopathic epiretinal membrane (ERM) patients after vitrectomy and ERM removal with or without additional indocyanine green (ICG)-assisted internal limiting membrane (ILM) peeling.

METHODS

The medical records of 43 patients with an idiopathic ERM that underwent vitrectomy and ERM removal between July 2007 and April 2010 were reviewed. The patients were divided into two groups: triamcinolone-assisted simple ERM peeling only (group A, n = 23) and triamcinolone-assisted ERM peeling followed by ICG staining and peeling of the remaining internal ILM (group B, n = 20).

RESULTS

No difference was found between the two groups in terms of visual acuity, macular thickness, P1 amplitude or implicit time on multifocal-electroretinogram (mfERG) at six and 12 months postoperatively. In group B, ICG staining after ERM peeling demonstrated that the ILM had been removed together with the ERM in 12 eyes (60%), and all 12 eyes showed punctate retinal hemorrhages during ERM peeling. There was no recurrence of an ERM in either group.

CONCLUSIONS

Additional procedures involving ICG staining and ILM peeling during ERM surgery do not appear to have an additive effect on the clinical outcomes in terms of visual acuity, retinal function based on mfERG, or recurrence rate.

Dynamic increase in extracellular ATP accelerates photoreceptor cell apoptosis via ligation of P2RX7 in subretinal hemorrhage

Photoreceptor degeneration is the most critical cause of visual impairment in age-related macular degeneration (AMD). In neovascular form of AMD, severe photoreceptor loss develops with subretinal hemorrhage due to choroidal neovascularization (CNV), growth of abnormal blood vessels from choroidal circulation. However, the detailed mechanisms of this process remain elusive. Here we demonstrate that neovascular AMD with subretinal hemorrhage accompanies a significant increase in extracellular ATP, and that extracellular ATP initiates neurodegenerative processes through specific ligation of Purinergic receptor P2X, ligand-gated ion channel, 7 (P2RX7; P2X7 receptor). Increased extracellular ATP levels were found in the vitreous samples of AMD patients with subretinal hemorrhage compared to control vitreous samples. Extravascular blood induced a massive release of ATP and photoreceptor cell apoptosis in co-culture with primary retinal cells. Photoreceptor cell apoptosis accompanied mitochondrial apoptotic pathways, namely activation of caspase-9 and translocation of apoptosis-inducing factor (AIF) from mitochondria to nuclei, as well as TUNEL-detectable DNA fragmentation. These hallmarks of photoreceptor cell apoptosis were prevented by brilliant blue G (BBG), a selective P2RX7 antagonist, which is an approved adjuvant in ocular surgery. Finally, in a mouse model of subretinal hemorrhage, photoreceptor cells degenerated through BBG-inhibitable apoptosis, suggesting that ligation of P2RX7 by extracellular ATP may accelerate photoreceptor cell apoptosis in AMD with subretinal hemorrhage. Our results indicate a novel mechanism that could involve neuronal cell death not only in AMD but also in hemorrhagic disorders in the CNS and encourage the potential application of BBG as a neuroprotective therapy.

Two-step surgery for retinal detachment caused by myopic macular hole

Purpose

To report the results of a two-step operation for treating retinal detachments caused by macular holes in high-myopic patients.

Methods

In the first part of the operation, pars plana vitrectomy, air–fluid exchange, and silicone oil injection were performed. At 4–6 months after the first operation, the second part of the operation was performed. This involved silicone oil removal and internal limiting membrane peeling under the aid of triamcinolone acetonide with or without gas tamponade.

Results

Four eyes (four patients) underwent surgery with this technique. All retinas were attached at the time of the second operation, when internal limiting membrane peeling could be performed easily and safely. The retina remained attached in all four eyes (100%) during 24–32 months of follow-up after the second operation.

Conclusion

Favorable surgical results were obtained with the two-step operation in the treatment of retinal detachments resulting from myopic macular holes.

Occult choroidal neovascularization after successful macular hole surgery treated with ranibizumab

PURPOSE

To report on a case that developed an atypical form of occult choroidal neovascularization (CNV) after successful macular hole surgery.

METHODS

Visual acuity change, color fundus photographs, fluorescein and indocyanine green angiograms, and optical coherence tomography results were compared throughout the follow-up duration.

PATIENTS

A 64-year-old woman with a macular hole in the right eye and drusen in both eyes underwent pars plana vitrectomy, internal limiting membrane peeling, and gas tamponade. One month after the operation she developed occult CNV, in which pigment epithelial detachment and fine retinal pigment epithelial (RPE) layer wrinkles were observed under the completely sealed macular hole. After 3-monthly intravitreal injections of ranibizumab, the lesion did not change significantly.

CONCLUSION

CNV can develop after otherwise successful macular hole surgery, especially in patients with pre-existing aging changes in the macula, such as drusen. Care should be taken in such patients, to prevent the development of CNV after macular hole surgery.

Unanticipated vision loss after pars plana vitrectomy

Although advances in vitreoretinal surgical techniques and technology have helped to minimize the risks associated with surgical manipulation of the retina, retinal pigment epithelium, and optic nerve, unanticipated or unexplained visual loss still occurs. We review causes of vision loss encountered after pars plana vitrectomy, including retinal toxicities, vascular events, and optic neuropathies, and we suggest strategies to limit or prevent them.

Toxicity profiles of subretinal indocyanine green, Brilliant Blue G, and triamcinolone acetonide: a comparative study

BACKGROUND

This study introduces a novel porcine model to examine the histopathological and electrophysiological consequences of retinotoxicity exerted by dyes commonly used for internal limiting membrane (ILM) staining.

METHODS

Indocyanine green (ICG) 0.5 mg/ml, Brilliant Blue G (BBG) 0.25 mg/ml and triamcinolone acetonide (TA) 13 mg/ml was injected subretinally in 12 vitrectomized pig eyes. At 6 weeks, retinas were examined by multifocal electroretinography (mfERG), ophthalmoscopy, fluorescein angiograpy, histopathology, and apoptosis assay.

RESULTS

mfERG responses were significantly lower in ICG-injected eyes than in healthy fellow eyes (p = 0.039). The ratio between injected eyes and healthy fellow eyes was lower in the ICG group than in the BBG (p = 0.009) and TA group (p = 0.025). No difference between BBG and TA existed. All retinas were reattached, and fluorescein angiographies showed a window defect corresponding to the injected areas but no blood-retina barrier break-down. Histopathology confirmed damage to the outer retina after ICG, but not after BBG and TA. No apoptosis was found at 6 weeks.

CONCLUSIONS

Subretinal ICG induces histological and functional damage to the retina, suggesting that ICG should be used with caution in macular hole surgery, where subretinal migration can occur. In contrast, BBG and TA appear safe after subretinal injection.

Use of autologous whole blood during internal limiting membrane peeling and macular hole surgery is protective for indocyanine green toxicity

OBJECTIVE

To compare indocyanine green (ICG)-assisted internal limiting membrane (ILM) peeling with and without autologous whole blood (WB) protection during macular hole repair surgery.

MATERIAL AND METHODS

We retrospectively reviewed 50 eyes with an idiopathic macular hole. Group 1 contained 22 eyes that underwent ILM peeling with WB protection and group 2 contained 28 eyes that underwent ILM peeling without WB. Anatomic and visual results were compared.

RESULTS

After surgery, macular hole closure was achieved in 96% of the group 1 eyes and in 93% of the group 2 eyes. The preoperative mean best-corrected visual acuity (BCVA) was logarithm of the minimum angle of resolution (logMAR) 0.95 in group 1 and logMAR 0.89 in group 2 (p = .544). The postoperative mean BCVA was logMAR 0.57 in group 1 and logMAR 0.92 in group 2 (p = .017).

CONCLUSION

Macular hole surgery protected with WB facilitates improved visual recovery in ICG-assisted ILM peeling.

Blood-assisted internal limiting membrane peeling for macular hole repair

PURPOSE

To evaluate the efficacy of autologous heparinized whole blood in assisting internal limiting membrane (ILM) peeling by coating the ILM for macular hole (MH) repair.

DESIGN

Prospective, interventional case series.

PARTICIPANTS

Twenty-nine patients (32 eyes) who underwent blood-assisted ILM peeling for MH repair.

METHODS

Patients in whom stage 2-4 idiopathic MHs had developed and who desired surgery were enrolled in this study. After core vitrectomy, autologous heparinized whole blood was applied to cover the macula and to coat the surface of the macular area in the fluid-filled vitreous cavity. The redundant blood was removed and only a very thin film of blood was left on the macular area. The blood-coated ILM was removed by forceps in a circular fashion. To confirm the removed membrane was the ILM, the first 10 specimens were examined by electron microscopy (EM).

MAIN OUTCOME MEASURES

The MH closure rate, the interval mean visual acuity (before and after surgery), retinal changes, and the EM results of the ILM specimens.

RESULTS

All 32 eyes in 29 patients completed 12 months of follow-up. The ILM were coated by autologous heparinized whole blood, removed without difficulty, and confirmed by EM. The whole blood highlighted the contrast of the coated and noncoated areas during the ILM peeling procedure. The MHs were closed in all surgical eyes with a single surgery (100%). Compared with study entry, the mean logMAR best-corrected visual acuity 12 months after surgery improved significantly (1.02 and 0.53, respectively; P<0.001). At 12 months of follow-up, 31 eyes (96.9%) had stable or improved vision. No toxic fundus changes were observed during follow-up.

CONCLUSIONS

Autologous heparinized whole blood coated the ILM and facilitated visibility during ILM peeling. Autologous heparinized whole blood is a cost-effective and useful tool for assisting MH surgery.

Vital staining with indocyanine green: a review of the clinical and experimental studies relating to safety

Indocyanine green (ICG) is extremely effective when used as a vital stain during macular hole surgery. By staining the internal limiting membrane, ICG facilitates removal of this delicate and sometimes hard to visualize structure. There is, however, considerable debate regarding its safety. This review considers the clinical and experimental studies of ICG and a related agent, infracyanine green. Some clinical papers show visual field defects, reduced visual acuity, and persistence of ICG at the macula and optic nerve. Other clinical studies fail to demonstrate toxicity. The experimental studies are also conflicting, but there are emerging trends. These suggest that surgeons who continue to use ICG should use concentrations not greater than 0.05 mg/ml, in fluid-filled eyes, with short exposure times, iso-osmolar solutions, and avoid proximal or prolonged endoillumination of stained tissue. A smaller number of studies suggest that infracyanine green produces similar staining to ICG, and may possibly be safer, but there are too few well-designed studies to reach a conclusion. Although the use of ICG continues, on the balance of evidence, this review suggests that it is has the potential to produce subtle visual damage.

Iatrogenic retinal traumas in ophthalmic surgery

BACKGROUND

To describe the main retinal iatrogenic traumas possibly related to ophthalmic surgery and the precautions to be adopted to avoid them.

METHODS

The article reviews the main peer-reviewed literature concerning retinal injuries caused by surgically related maneuvers. Safety measures alleged to inhibit any possible iatrogenic damage are also evaluated.

RESULTS

Photochemical damage of the retina, retinal complications after strabismus surgery, retinal complications related to local anesthesia for ophthalmic surgery, retinal damage during cataract surgery and retinal damage during vitreoretinal surgery are the most common iatrogenic retinal injuries. Their incidence is related to risk factors peculiar to each condition.

CONCLUSIONS

Ophthalmic surgeons are aware that there are a number of circumstances in which several undesirable retinal iatrogenic injuries might occur, sometimes with serious consequences. This is why surgeons should take every precaution at each surgical step to avoid any possible retinal iatrogenic damage.

Mechanisms of intravitreal toxicity of indocyanine green dye: implications for chromovitrectomy

PURPOSE

Indocyanine green (ICG) dye was shown to improve the visualization of preretinal tissues during chromovitrectomy. However, controversy arose regarding the safety of intravitreal ICG application, because worse functional outcomes and a higher incidence of retinal pigment epithelium (RPE) changes and visual field defects were reported. The mechanisms of ICG-related toxicity and their relevance for chromovitrectomy are reviewed.

METHODS

A literature search was performed from 1998 through 2005 for relevant information related to the mechanisms of intravitreal ICG toxicity. Animal and clinical data on intravitreal ICG-related toxicity were collected to clarify the mechanisms of the risk of intravitreal ICG injection.

RESULTS

Over 80 controversial in vitro, ex vivo, and in vivo animal investigations as well as clinical reports on intravitreal ICG staining were found in the literature. The main postulated mechanisms of intravitreal ICG-related toxicity were as follows: biochemical direct injury to the ganglion cells/neuroretinal cells, RPE cells, and superficial retinal vessels; apoptosis and gene expression alterations to either RPE cells or neuroretinal cells; osmolarity effect of ICG solution on the vitreoretinal interface; light-induced injury; and mechanical cleavage effect to the internal limiting membrane/inner retina. Whereas the exact mechanism of intravitreal ICG-related damage remains yet to be determined, most animal experiments proposed that ICG dye has a dose-dependent toxic effect on retinal tissue. This hypothesis was supported by clinical data, because better functional outcomes were obtained when low dye concentrations and short incubation times were reported.

CONCLUSIONS

Much evidence supports that ICG dye has a dose-dependent toxic effect on the retina. Therefore, the following recommendations to minimize toxic effects on the retina are proposed: dye injection in concentrations as low as possible; avoidance of repeated ICG injections onto bare retina; dye injection far from the macular hole to prevent direct dye contact with the RPE; short incubation time of ICG in the vitreous cavity to diminish the concentration in contact with the retinal tissue; and the light pipe kept far from the retina throughout the whole surgical procedure.

PREVENTING THE DEPOSITION OF TRIAMCINOLONE IN MACULAR HOLE BY USE OF WHOLE BLOOD IN TRIAMCINOLONE-ASSISTED MEMBRANE PEELING

PURPOSE

To prevent triamcinolone acetonide (TA) deposition in the macular hole by use of whole blood during TA-assisted internal limiting membrane (ILM) peeling.

METHODS

The prospective, interventional case series study included 18 consecutive idiopathic macular holes (18 patients) that underwent TA-assisted internal limiting membrane (ILM) peeling for macular hole treatment. After core vitrectomy, autologous whole blood was applied to cover the macular hole. Pre-prepared TA solution was gently injected onto the macular area. Residual TA particles were removed after ILM peeling. Closure rate of macular hole, preoperative and postoperative median visual acuity, and retinal changes were evaluated.

RESULTS

Autologous whole blood prevented the deposition of TA particles in the macular hole. The ILM could be recognized after TA-assisted visualization for removal. Average follow-up time was 8.6 months. The hole was closed with one surgery in 17 eyes (94%); visual acuity improved in 15 eyes (83%). Preoperative median best-corrected visual acuity was 20/100 (range = 20/400-20/50). Postoperative median best-corrected visual acuity was 20/40 (range = counting fingers-20/20).

CONCLUSIONS

Whole blood can prevent TA particle deposition in the macular hole. Potential toxicity of TA on retinal pigment epithelium and retina also may be reduced.

Biocompatibility of brilliant blue G in a rat model of subretinal injection

PURPOSE

To evaluate the toxicity of brilliant blue G (BBG) compared with those of indocyanine green (ICG) and trypan blue (TB) in a rat model of subretinal injection.

METHODS

Retinal detachment was produced by subretinal injection of the dyes. The biocompatibility of BBG (0.25 mg/mL) was evaluated over 2 months and 2 weeks by ophthalmic examinations. The eyes were enucleated and analyzed by light, fluorescence, as well as transmission electron microscopy. Apoptotic cell death was detected by TdT-dUTP terminal nick-end labeling. The results were compared with those for ICG (5 mg/mL) and TB (1 mg/mL).

RESULTS

ICG caused retinal degeneration and retinal pigment epithelial (RPE) cell atrophy 2 weeks after subretinal injection. Apoptotic cell death was detected in the inner and outer nuclear layers and the RPE layer, especially the photoreceptors. TB caused less retinal degeneration, mainly in the area detached by the subretinal injection. BBG had no detectable toxic effects after 2 months and 2 weeks. Apoptotic cell death was detected in the ICG and TB groups, mainly in the photoreceptors.

CONCLUSIONS

Subretinal injection of the dyes caused retinal cell degeneration at lower concentrations than those reported for intravitreous injection. However, subretinal injection of BBG at 0.25 mg/mL appeared to provide satisfactory biocompatibility.

ANATOMICAL AND VISUAL OUTCOMES OF IDIOPATHIC MACULAR HOLE SURGERY WITH INTERNAL LIMITING MEMBRANE REMOVAL USING LOW-CONCENTRATION INDOCYANINE GREEN

PURPOSE

To report the anatomical, visual, and optical coherence tomography (OCT) results of using a brief application of a low concentration of indocyanine green (ICG) to assist the removal of internal limiting membrane (ILM) during idiopathic macular hole repair.

METHODS

Retrospective, interventional, noncomparative case series of 59 eyes of 57 patients with stage 2, 3, or 4 idiopathic macular holes who underwent pars plana vitrectomy with removal of ILM assisted by a brief (<30 seconds) intravitreal application of 0.125% (1.25 mg/mL) ICG.

RESULTS

The median follow-up period was 13 months (range, 2-40 months). Anatomical closure of the macular hole was achieved in 58 eyes (98%) with a single surgery. Visual acuity improved from a preoperative mean of 20/100 to 20/60 postoperatively (P < 0.0001). Twenty-nine eyes (49%) had postoperative visual acuity of 20/50 or better. Visual acuity improved by > or =2 lines in 43 eyes (73%) and between 0 and 2 lines in 13 eyes (22%) and decreased in 3 eyes (5%). Postoperative OCT showed closure of macular hole with normal foveal depression in 49 (89%) of 55 eyes.

CONCLUSION

A brief application of ICG at a low concentration appears to provide a safe and effective way of assisting ILM peeling during idiopathic macular hole surgery.

Vergleich des ILM-Peelings mit und ohne Einsatz von Indozyaningrün

BACKGROUND

Pars plana vitrectomy with internal limiting membrane (ILM) peeling is the best known therapy for idiopathic macular holes. Indocyanine green (ICG) is useful for staining the ILM, although there is a dose related toxic effect on the inner retinal layers. We compared outcome results with and without the use of ICG.

METHOD

Data from 61 patients with idiopathic macular holes, who underwent macular hole surgery were analyzed retrospectively. ICG was used on 36 eyes while for 25 eyes it was not used. After calculating logMAR, differences in visual acuity between both groups were analyzed for significance using the Mann-Whitney-U-Test.

RESULTS

The logMAR for the entire group was 0.71+/-0.30 (20/100) preoperatively, after 1 month 0.71+/-0.36 (20/100), after 3 months 0.57+/-0.26 (20/80), after 6 months 0.54+/-0.38 (20/66) and after 12 months 0.36+/-0.32 (20/50). There were no significant differences between groups.

CONCLUSION

There seem to be no significant differences in the development of visual acuity and the occlusion rate between patients treated with or without the use of ICG.

Molecular contrast optical coherence tomography: A pump-probe scheme using indocyanine green as a contrast agent

The use of indocyanine green (ICG), a U.S. Food and Drug Administration approved dye, in a pump-probe scheme for molecular contrast optical coherence tomography (MCOCT) is proposed and demonstrated for the first time. In the proposed pump-probe scheme, an optical coherence tomography (OCT) scan of the sample containing ICG is first acquired. High fluence illumination (approximately 190 kJ/cm2) is then used to permanently photobleach the ICG molecules--resulting in a permanent alteration of the overall absorption of the ICG. A second OCT scan is next acquired. The difference of the two OCT scans is used to determine the depth resolved distribution of ICG within a sample. To characterize the extent of photobleaching in different ICG solutions, we determine the cumulative probability of photobleaching, phi(B,cum), defined as the ratio of the total photobleached ICG molecules to the total photons absorbed by the ground state molecules. An empirical study of ICG photobleaching dynamics shows that phi(B,cum) decreases with fluence as well as with increasing dye concentration. The quantity phi(B,cum) is useful for estimating the extent of photobleaching in an ICG sample (MCOCT contrast) for a given fluence of the pump illumination. The paper also demonstrates ICG-based MCOCT imaging in tissue phantoms as well as within stage 54 Xenopus laevis.

Modified technique for safer indocyanine-green-assisted peeling of the internal limiting membrane during vitrectomy for macular hole repair

BACKGROUND

During macular hole surgery, indocyanine green (ICG) has access to the subretinal space and can lead to toxic and phototoxic damage of the retinal pigment epithelium (RPE). To reduce its toxicity and to avoid contact between ICG and the RPE, we have developed a modified technique by using autologous whole blood.

METHODS

Thirty-one eyes underwent vitrectomy for idiopathic macular hole repair. Autologous whole blood (0.1 ml) was injected into the buffered saline solution (BSS)-filled vitreous cavity over the posterior pole and aspirated with a flute cannula. A small clot remained covering the macular hole. The internal limiting membrane (ILM) was stained by using 0.05% ICG solution. The ICG was dissolved in 5% glucose to obtain an iso-osmotic solution. This ICG was injected into the BSS-filled vitreous cavity over the posterior pole and removed after 10 s. The ILM was peeled and a long-acting gas tamponade applied. Pre- and postoperative best-corrected visual acuity and optical coherence tomography (OCT) findings are reported.

RESULTS

Macular hole closure was achieved in 30 of 31 eyes (97%). The mean preoperative logMAR acuity was 0.99 (range: 0.4 to 2.0). Mean postoperative logMAR acuity was 0.496 (range: 0.0 to 1.0). The average improvement in vision was 0.66 logMAR units (range: 1.5 to 0.0). No postoperative RPE alterations were observed biomicroscopically or on OCT.

CONCLUSION

This surgical technique leads to favorable anatomic and functional results. ICG toxicity is reduced by modifying osmolarity, concentration and contact time and by injecting ICG under BSS. Autologous whole blood acts as a mechanical barrier and prevents ICG from entering in the subretinal space.

Retinal ganglion cells toxicity caused by photosensitising effects of intravitreal indocyanine green with illumination in rat eyes

AIM

To investigate the effects of indocyanine green (ICG) with or without illumination on rat retinal ganglion cells (RGC) and retinal morphology.

METHODS

Intravitreal injections of 1.0 mg/ml ICG solution were performed in rat eyes with or without subsequent illumination for 5 minutes. Eyes in the control group had intravitreal injections of balanced salt solution with illumination. Retrograde labelling of RGC with 6% Fluoro-Gold was performed 1 month later and RGC densities were compared between the three groups. Light microscopy with measurements of outer nuclear layer (ONL) and inner nuclear layer (INL) thicknesses were also performed and compared.

RESULTS

Eyes with ICG without illumination showed insignificant reduction in RGC density compared with the control group (p = 0.28), whereas a significant decrease in RGC density was found in eyes that had ICG injection with illumination (p = 0.036). A significant increase in ONL thickness was also observed in the ICG with illumination treated eyes compared with the ICG without illumination and the control groups (p<0.001). No significant difference in INL thickness was observed between the three groups.

CONCLUSIONS

Intravitreal injection of 0.1 mg/ml ICG in rat eyes followed by illumination resulted in photosensitising toxicity to RGC. Lower ICG concentration or illumination level should be considered when performing ICG assisted macular surgery.

The effects of indocyanine green and endoillumination on rabbit retina: an electroretinographic and histological study

AIM

To evaluate the functional and morphological retinal toxicity associated with intravitreal injection of indocyanine green (ICG) dye in rabbit eyes during vitrectomy with endoillumination.

METHODS

20 eyes of 10 New Zealand pigmented rabbits were used in the study. All eyes underwent pars plana vitrectomy and removal of posterior vitreous cortex under endoillumination. In one eye of each rabbit, intravitreal injection of 0.1 ml of 2.5 mg/ml ICG was applied for 30 seconds followed by 10 minutes of endoillumination. The control eye had endoillumination only without ICG injection. Dark adapted and light adapted electroretinograms (ERGs) were performed before the surgery and 1 week after surgery for serial comparisons. Rabbits were killed 1 week after surgery and eyes were enucleated for histological examination.

RESULTS

Serial ERG comparisons showed significant reduction in the light adapted a-wave amplitude (p = 0.037) and significant delays in the dark adapted and light adapted b-wave latencies (p = 0.020 and p = 0.038, respectively) in the ICG treated eyes. Histological examinations demonstrated loss of photoreceptor outer segments with focal absence of photoreceptors in some areas in the ICG injected eyes.

CONCLUSIONS

Vitrectomy followed by intravitreal injection of 2.5 mg/ml ICG for 30 seconds with endoillumination may result in retinal toxicity causing functional and morphological retinal damages in rabbit eyes. The lowest concentration of ICG should be used if necessary for intraocular use to prevent potential retinal toxicity.

Intravitreal Staining of the Internal Limiting Membrane Using Indocyanine Green in the Treatment of Macular Holes

Surgical management of macular holes consists of pars plana vitrectomy, removal of the posterior hyaloid facia, and peeling of the epiretinal membranes (ERM). Additionally, removal of the internal limiting membrane (ILM) may enable an increase in the anatomic and functional success rates. However, recognition of fine ILM is difficult thus increasing the time that the macula is exposed to intraoperative light. Staining the ILM with indocyanine green (ICG) dye during vitrectomy facilitates recognition of the ILM and assures that all adjacent ERM are removed. Therefore, ICG-assisted ILM peeling has gained worldwide popularity among vitreoretinal surgeons. However, there are some concerns about the intravitreal ICG application. Reports in the literature described a variety of application techniques using different concentrations. The postoperative outcomes were controversial reporting heterogeneous anatomical and functional outcomes after ICG application, as well as descriptions of adverse effects related to the dye. We discuss the indications, techniques, surgical results, and complications after intravitreal ICG injection for the treatment of macular holes.

Clinical evaluation of the use of indocyanine green for peeling the internal limiting membrane in macular hole surgery

BACKGROUND

To evaluate the role of indocyanine green (infracyanine) in macular hole surgery.

METHODS

A retrospective review of 38 consecutive eyes with macular hole, operated on with internal limiting membrane peeling (ILM), using or not using infracyanine (ICG), diluted in glucose 5% and filtered. Anatomical and functional results were analysed in each group, using visual field testing, fluorescein fundus angiography and particularly blue filter fundus photographs for the detection of retinal pigment epithelial changes and lesions of optic nerve fibres layer.

RESULTS

Fifteen eyes underwent surgery without ICG and 23 eyes with ICG. The mean period of follow-up was 10 months. The duration of surgery was significantly lower in the group with ICG than without (P < 0.001). Overall, 84% of the holes closed without difference between both groups. The improvement in vision at 1, 6 and 12 months was similar in both groups. Fewer defects in the optic nerve fibres layer were observed in the group with ICG than without (P = 0.02). Staining with ICG revealed the presence of an associated epiretinal membrane in 61% of eyes, whereas it was clinically visible in only 17.5% before surgery.

CONCLUSION

Using ICG for ILM peeling produced similar visual results to those obtained without ICG. It reduced significantly the duration of surgery and the trauma to the optic nerve fibres layer, without increasing the risk of retinal pigment epithelial damage. However, in the light of recent reports about the possible toxicity of ICG, its use should be restricted in clinical practice to difficult cases.

Prevention of Indocyanine Green Toxicity on Retinal Pigment Epithelium with Whole Blood in Stain-Assisted Macular Hole Surgery

PURPOSE

To examine whether whole blood prevents indocyanine green (ICG) toxicity on in vitro retinal pigment epithelium (RPE) and prevents RPE staining in ICG-assisted macular hole (MH) surgery.

DESIGN

In vitro study and prospective case series.

PARTICIPANTS

In vitro study and 20 patients who underwent ICG-assisted MH surgery (20 eyes).

METHODS

In the in vitro study, cultured human RPE cells were covered with balanced saline solution (BSS), heparinized whole blood, plasma, or packed red blood cells, then exposed to various concentrations of ICG. One cohort was incubated in the dark; the other cohort was exposed to light. Indocyanine green toxicity was evaluated by mitochondrial dehydrogenase assay. In the clinical study, a prospective noncomparative review of 20 consecutive patients (20 eyes) with stage 3 to stage 4 MH who underwent surgery with ICG to stain the internal limiting membrane (ILM) was performed. Indocyanine green solution (0.5 mg/ml) was used to stain the ILM after autologous whole blood covered the macular hole area. Postoperative staining of ICG on RPE was detected by an infrared-sensitive camera.

MAIN OUTCOME MEASURES

Cultured human RPE cell viability, macular hole closure rate, median visual acuity preoperatively and postoperatively, postoperative ICG staining, and retinal changes.

RESULTS

Cultured human RPE cells covered by whole blood or plasma showed no decrease of mitochondrial dehydrogenase even in 5.0 mg/ml concentration of ICG for 20 minutes with or without light exposure. Conversely, those exposed to ICG and covered with BSS demonstrated a significant decrease of mitochondrial dehydrogenase after incubation in 5, 2.5, and 1.0 mg/ml for 20 minutes in the dark and in 5 to 0.05 mg/ml with light. Clinically, no postoperative staining on RPE was detected. No atrophic RPE changes or other retinal changes were observed in the previous MH area that was covered by autologous whole blood in all 20 eyes on average follow-up of 10.6 months. The hole closed in 19 eyes (95%) on first surgery. Visual acuity improved in 17 eyes (85%) on most recent follow-up.

CONCLUSIONS

Whole blood prevents ICG toxicity in RPE cell culture and prevents staining of RPE in surgery of MH when the ILM is stained with ICG.

STAINING OF THE INTERNAL LIMITING MEMBRANE WITH INTRAVITREAL TRIAMCINOLONE ACETONIDE

PURPOSE

To evaluate the use of triamcinolone acetonide to stain the internal limiting membrane (ILM) during vitreoretinal surgery.

METHODS

A prospective clinical interventional case series study was performed, including 16 patients who underwent pars plana vitrectomy. Seven patients had proliferative diabetic retinopathy with macular edema. Seven patients had epiretinal membranes. One patient had a retinal detachment with a cystoid macular edema and proliferative vitreoretinopathy. One patient had a pseudophakic cystoid macular edema. After vitrectomy, 2 mL triamcinolone acetonide suspension was injected into the vitreous cavity. The ILM was peeled, as it was evidenced by the particles of triamcinolone that adhered to its surface. The ultrastructure of tissue harvested during surgery was analyzed using transmission electron microscopy in selected cases to confirm the presence or absence of ILM.

RESULTS

After the injection of triamcinolone, the visualization of the vitreous base and hyaloid was excellent in all patients. The particles of triamcinolone deposited on the retinal surface enabled the ILM to be stained. Once removed, the ILM was clearly distinguishable, floating in the vitreous cavity with particles of triamcinolone adhering to its surface. Ultrastructural analysis of tissue collected during vitrectomy confirmed that the removed tissue represented ILM.

CONCLUSION

We observed that triamcinolone acetonide can be useful in staining the internal limiting membrane, thus greatly facilitating the retinal ILM peeling. The absence of particles of triamcinolone on the underlying retina enables the area where the ILM has already been removed to be identified.

Effect of indocyanine green on the growth and viability of cultured human retinal pigment epithelial cells

The aim of this study was to evaluate the effects of indocyanine green (ICG), which is a fluorescent dye recently used for staining during manipulation of the internal limiting membrane (ILM) in surgery, on cultured human retinal pigment epithelial (HRPE) cells. Different concentrations, up to 0.25% (weight/volume), of ICG were added to the culture medium, which contained the cultured human RPE cells. Then the cell-growth curve and cell viability were assayed with a direct cell count and MTS cell proliferation kit, respectively. Two (2) models of experimentations, a dose-response group and a short-term application group, were designed. We obtained data for IC(50) values for 24-, 48-, and 72-hour ICG treatments, which were 0.062%, 0.041%, and 0.035%, respectively. This implies that the longer the culture duration, the lower the concentration of ICG, which can inhibit the HRPE cells. In the group of 3-day sequential incubations with ICG treatment, a 0.01% concentration significantly inhibited HRPE growth. In addition, HRPE cells were damaged immediately after ICG treatment, and the damage was ICG dose-related. In the sequential 3-day incubation, compared to the control group, the surviving HRPE cells of each treated group had the same growth rate. In conclusion, ICG has a relatively toxic effect on cultured HRPE cells, even in much lower concentrations than clinical nondilution status (0.25%). Since an ICG toxic effect on HRPE cells was found in our study (in vitro), we highly recommend staining the ILM with as low a concentration of ICG as possible, and washing out the residual intravitreal ICG as thoroughly as possible after finishing the peeling of the ILM.

Long-term follow-up of indocyanine green–assisted peeling of the retinal internal limiting membrane during vitrectomy surgery for idiopathic macular hole repair

OBJECTIVE

To determine the long-term efficacy of indocyanine green (ICG)-assisted retinal internal limiting membrane (ILM) peeling during macular hole repair.

DESIGN

Retrospective, interventional, noncomparative case series.

PARTICIPANTS

One hundred twenty-one eyes of 114 patients with stage 2, 3, or 4 idiopathic macular holes that underwent ICG-assisted macular hole repair during the period of August 1999 to January 2003.

INTERVENTION

All eyes underwent a pars plana vitrectomy, including peeling of the posterior cortical hyaloid when necessary. Indocyanine green dye (0.5%) was instilled over the macula, and after removal of the ICG, the retinal ILM was peeled. Medium- to long-acting gas tamponade was used in all cases, and all patients were asked to position themselves facedown for 1 to 2 weeks.

MAIN OUTCOME MEASURES

Long-term postoperative anatomic results, visual acuity (VA), and complications.

RESULTS

Patients were observed postoperatively for an average of 26 months (range, 12-53). Anatomic closure of the macular hole was achieved in 118 eyes (98%) with a single surgery. Reoperation was successful at closing 2 of the 3 macular holes that did not close initially. One macular hole reopened 16 months after the original surgery, and the patient has not yet undergone further surgery. Visual acuity improved by > or =2 lines in 116 eyes (96%). Mean visual improvement after surgery was 6 lines (range, 0-14), and 96 eyes (79%) achieved a final VA of 20/50 or better. There were no intraoperative or postoperative complications attributed to the use of ICG.

CONCLUSIONS

Long-term follow-up of patients who underwent ICG-assisted ILM peeling for idiopathic macular hole repair demonstrates excellent anatomic and visual results.

Functional and anatomic results of macular hole surgery complicated by massive indocyanine green subretinal migration

PURPOSE

To report the functional and anatomic results of macular hole (MH) surgery complicated by massive subretinal migration of indocyanine green (ICG) dye.

DESIGN

Interventional case report.

METHODS

We performed standard pars plana vitrectomy surgery for a stage 3, senile idiopathic MH. After posterior vitreous detachment and vitreous removal, we instilled 2 ml of ICG (0.5%, 270 mOsm); the surgery was complicated by diffuse subretinal migration of the ICG dye but peeling of the internal limiting membrane (ILM) was performed (despite the obvious difficulties from the low contrast between the green-stained ILM overlying a green-stained subretinal space) and the rest of the procedure was completed with a final injection of 16% C3F8.

RESULTS

Post-surgical optical coherence tomography confirmed the anatomic closure of the MH. Digital photography with the excitation and barrier filters for ICG showed a striking autofluorescence along the inferior vascular arcade, which remained intense 7 months after surgery. Despite the massive subretinal migration of ICG, visual acuity (VA) improved to 20/30.

CONCLUSIONS

This is the first report of VA recovery despite massive subretinal migration of ICG dye during MH surgery. Subretinal migration of ICG dye may be a potential complication during MH surgery; this should alert the surgeon to limit its use, despite the possible absence of clinically apparent toxic effects.

Outcomes of macular hole surgery: implications for surgical management and clinical governance

PURPOSE

The optimal method and timing of the surgical treatment for idiopathic macular holes remains unknown. The aim of this retrospective study was to identify factors associated with anatomical and visual success in macular hole surgery.

METHODS

Case records of 55 patients undergoing macular hole surgery at three units in the 2-year period up to July 2002 were reviewed to identify factors associated with anatomical and visual success. The following potential prognosticators were evaluated: patient age, hole stage, hole latency prior to surgery, preoperative acuity, simultaneous phacoemulsification, and intraocular lens implantation, internal limiting membrane peeling with and/or without indocyanine green, and postoperative posturing.

RESULTS

The duration of preoperative symptoms, indocyanine green-assisted internal limiting membrane peeling, hole stage, and better preoperative visual acuity were associated with both anatomical success and regaining a postoperative visual acuity of 6/12 or better.

DISCUSSION

The closure rate in patients undergoing surgery within 1 year of onset was 94.0%, and in those waiting 1 year or more it was 47.4%. Clinical governance and quality issues should dictate that NHS macular hole surgery is available to all within 1 year of onset. This study showed no adverse effect of ICG dye retinal staining. The results support the use of a 'patient-friendly' approach of simultaneous cataract surgery with no prone postoperative posturing.