Effects of Subretinal Injections of Indocyanine Green, Trypan Blue, and Glucose in Rabbit Eyes

Macular toxicity of vital dye after pars plana vitrectomy for idiopathic epiretinal membrane: A case report

Purpose

To describe the first reported case of outer retinal damage following the use of Membrane Blue Dual for epiretinal membrane (ERM) surgery.

Observations

A 74-year-old female underwent pars plana vitrectomy and ERM peeling assisted with Membrane Blue Dual for an idiopathic ERM. Postoperatively, the patient reported a decline in visual acuity with a central scotoma. Fundus examination revealed a well-defined retinal whitening in the peeling area which evolved into pigmentary changes as confirmed by fundus autofluorescence. Optical coherence tomography (OCT) showed loss of outer retinal layers and irregular mottling of the retinal pigment epithelium. Fundus and OCT appearance remained unchanged after 4 months and the central scotoma also persisted.

Conclusions and Importance

ERM surgery assisted with Membrane Blue Dual can induce major changes in retinal pigment epithelium and outer retinal layers. This adverse event which probably results from combined light and dye toxicity should be considered by all surgeons even though its occurrence is rare.

Comparative effects of commonly used intraocular dyes on the viability of human retina Müller cells

This study investigated the in vitro effect of various vital dyes in common clinical use on human Müller cell viability, and it compared the toxicity of these dyes using a cell culture model. Müller cells were exposed to a series of concentrations (1 %, 0.5 %, 0.25 %, and 0.125 % or 12.9 mM, 6.45 mM, 3.22 mM and 1.61 mM) of Indocyanine green (ICG) for 2, 24, 48, and 72 h. Similarly, groups of Müller cells were stained with "Heavy" brilliant blue G (HBBG), Trypan blue (TB) (0.15 %, or 1.56 mM), Membrane-blue-dual (MBD), and ICG (0.25 %, or 3.22 mM) or BBG (0.025 %, or 0.3 mM) with glucose (GS) (50 %, 66 % and 75 % or 2.78 M, 3.67 M and 4.17 M) for 30, 60, and 120 s. Cell viability was measured with the Cell Counting Kit-8 (CCK-8) and Lactate Dehydrogenase (LDH) release assays. We found that high stain concentration and long exposure time resulted in increased toxicity to Müller cells. Nevertheless, ICG seemed to be safe at the clinically relevant concentration of 0.25 % (3.22 mM) in the short time of exposure. TB was safer than both HBBG and MBD, especially HBBG. Hypertonic GS as a dilution was not safe for Müller cells, and the negative effect was more obvious in 0.025 % (0.3 mM) BBG than that in 0.25 % (3.22 mM) ICG. This is the first report to observe the cytotoxicity of commonly used stains in clinical on human Müller cells in vitro, and to provide some basis for further studies, including in vivo investigation.

Internal limiting membrane flap technique in macular hole surgery

Vitrectomy combined with internal limiting membrane (ILM) peeling is popular for the treatment of macular hole (MH). However, the improvements of MH closure rate and postoperative visual acuity are not satisfactory especially in large and refractory MHs. Currently, the ILM flap technique has gradually been applied for the treatment of MH and achieved high MH closure rate. The ILM flap technique has many variations, including the difference of the size, shape, number, and manner in which the flaps put on the MHs. The ILM flap technique also has some auxiliary means including perfluoro-n-octane (PFO), dye, autologous blood and adhesive viscoelastics. There is controversy about the effects between several technique variations of ILM flap, and it needs to be explored in the future.

Vital Dyes in Vitreomacular Surgery

Vital dyes contain complex molecules with chromophores that stain living tissues and have greatly enhanced identification and removal of transparent vitreoretinal tissues during surgery. Several "chromovitrectomy" dyes are frequently used by vitreoretinal specialists, including indocyanine green, trypan blue, brilliant blue G, and triamcinolone acetonide; other dyes are also under investigation. Trypan Blue was approved by the U.S. Food and Drug Administration (FDA) for epiretinal membrane removal, and preservative-free triamcinolone acetonide was approved by the FDA for intraocular use. However, currently available chromovitrectomy dyes have their limitations, and of particular concern for some of them is the possibility for acute and chronic toxicity to the neurosensory retina and retinal pigmented epithelium. The potentially irreversible acute toxicity and other limitations, such as lack of long-term safety profiles, highlight the need for further advancements. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:788-798.].

Cellular-scale evaluation of induced photoreceptor degeneration in the living primate eye

Progress is needed in developing animal models of photoreceptor degeneration and evaluating such models with longitudinal, noninvasive techniques. We employ confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT) and high-resolution retinal imaging to noninvasively observe the retina of non-human primates with induced photoreceptor degeneration. Photoreceptors were imaged at the single-cell scale in three modalities of adaptive optics scanning light ophthalmoscopy: traditional confocal reflectance, indicative of waveguiding; a non-confocal offset aperture technique visualizing scattered light; and two-photon excited fluorescence, the time-varying signal of which, at 730 nm excitation, is representative of visual cycle function. Assessment of photoreceptor structure and function using these imaging modalities revealed a reduction in retinoid production in cone photoreceptor outer segments while inner segments appeared to remain present. Histology of one retina confirmed loss of outer segments and the presence of intact inner segments. This unique combination of imaging modalities can provide essential, clinically-relevant information on both the structural integrity and function of photoreceptors to not only validate models of photoreceptor degeneration but potentially evaluate the efficacy of future cell and gene-based therapies for vision restoration.

Photochemical degradation of trypan blue

Purpose

To investigate the photochemical degradation of trypan blue (TB) and to identify decomposition products.

Methods

Defined solution samples of TB and a mixture with lutein/zeaxanthin were exposed to blue light. Thermal degradation processes were ruled out using controls not subjected to irradiation. All samples were analyzed using optical microscopy, UV/Vis spectroscopy, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and nuclear magnetic resonance (NMR) spectrometry. Degradation kinetics were determined based on changes in absorbance; intermediates were identified by analyzing mass differences of characteristic fragment ion peaks within the fragmentation patterns, and assignments were verified by NMR.

Results

TB demonstrated a photochemical degradation, which can be triggered by lutein/zeaxanthin. Intermediates vary depending on the presence of lutein/zeaxanthin. The self-sensitized photodegradation of TB occurs under generation of dimethyl sulfate and presumed formation of phenol. In contrast, within the presence of lutein/zeaxanthin the decomposition of TB indicates the formation of methoxyamine and sulfonyl arin. Thermal degradation processes were not observed.

Conclusions

TB demonstrated a photodegradation that may be triggered by lutein/zeaxanthin and results in the formation of cytotoxic decomposition products. Our findings contribute to understand degradation mechanisms of TB and may elucidate previous clinical and experimental observations of cellular toxicity after TB application.

Modified technique of internal limiting membrane staining in idiopathic macular hole surgery

PURPOSE

To describe a new method of ILM staining with TB under perfluorocarbon in cases of full thickness idiopathic macular hole using the inverted ILM flap technique.

METHODS

This study was a prospective interventional case series that included 42 eyes of 42 patients who had full thickness idiopathic macular hole with a minimum diameter more than 400 µm. Patients consecutively underwent vitrectomy with inverted ILM flap technique using the modified ILM staining method.

RESULTS

Anatomic success was achieved in 40 patients (95.2%). The other two patients had flat-open macular holes with bare RPE (foveal defect of neurosensory retina). Among the 40 eyes with closed holes, 25 eyes were of the U-type closure (normal foveal contour) and 15 eyes were of the V-type closure (steep foveal contour). These 40 eyes remained closed during the 6 months follow-up period.

CONCLUSION

The modified technique of ILM staining using TB under PFCL is safe and effective in cases of idiopathic macular hole combined with the inverted ILM flap technique.

Clinically undetected retinal breaks causing retinal detachment: A review of options for management

The successful detection of retinal breaks is a critical step in rhegmatogenous retinal detachment surgery in order to prevent persistent/recurrent retinal detachments. Not all retinal breaks causing retinal detachments are obvious. Retinal breaks may be obscured by opacities that are either anterior segment related, lens related, or posterior segment related. Rules to identify breaks based on subretinal fluid configuration are more difficult to apply in pseudophakic, aphakic, and scleral buckle encircled eyes-and in eyes with repeat detachments and those with proliferative vitreoretinopathy. Exudative detachments exhibit characteristic features and must be ruled out. A thorough clinical examination preoperatively is important even if a vitrectomy is planned. We review the incidence and causes of undetected breaks, along with preoperative/clinical issues that may hinder break detection. We review the literature with respect to investigative approaches and techniques that are available to the vitreoretinal surgeon when primary breaks remain clinically undetected during the preoperative examination. We broadly divide the surgical approaches into ones where the surgeon utilizes techniques to pursue actively a search for breaks versus adopting a purely speculative approach. Advantages and disadvantages of various techniques are appraised. Intuitively one might argue that an encircling scleral buckle combined with vitrectomy would give higher single operation success than pars plana vitrectomy alone because "undetected" retinal breaks would be addressed by a 360° plombage. We could not confirm this concept. Newer techniques, such as pars plana vitrectomy augmented with dye extrusion or endoscopic-assisted pars plana vitrectomy, show encouraging results. Technological advances such as intraoperative optical coherence tomography will also help to broaden the vitreoretinal surgeon's armamentarium. At this time, there is no gold standard in terms of the recommended approach, and this is reflected in the many options that are available for management. The surgeon must consider the benefits versus the risk of their preferred approach.

Differential autophagic effects of vital dyes in retinal pigment epithelial ARPE-19 and photoreceptor 661W cells

Indocyanine green (ICG) and brilliant blue G (BBG) are commonly used vital dyes to remove internal limiting membrane (ILM) in vitreoretinal surgery. The vital dyes have shown cytotoxic effects in ocular cells. Autophagy is a stress responsive pathway for either protecting cells or promoting cell death. However, the role of autophagy in ocular cells in response to the vital dyes remains unknown. In this study, we found that ICG and BBG reduced cell viability in both human retinal pigment epithelial ARPE-19 and mouse photoreceptor 661W cells. ICG and BBG induced lipidated GFP-LC3-II and LC3-II in ARPE-19 and 661W cells. Combination treatment with the autophagy inhibitor chloroquine indicated that ICG and BBG reduced autophagic flux in ARPE-19 cells, whereas the vital dyes induced autophagic flux in 661W cells. Moreover, genetic and pharmacological ablation of autophagy enhanced vital dyes-induced cytotoxicity in ocular cells. Dietary supplements, including resveratrol, lutein, and CoQ10, induced autophagy and diminished the cytotoxic effects of ICG and BBG in ocular cells. These results suggest that autophagy may protect ARPE-19 and 661W cells from vital dyes-induced damage.

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.

Two-Step Reactivation of Dormant Cones in Retinitis Pigmentosa

Most retinitis pigmentosa (RP) mutations arise in rod photoreceptor genes, leading to diminished peripheral and nighttime vision. Using a pig model of autosomal-dominant RP, we show glucose becomes sequestered in the retinal pigment epithelium (RPE) and, thus, is not transported to photoreceptors. The resulting starvation for glucose metabolites impairs synthesis of cone visual pigment-rich outer segments (OSs), and then their mitochondrial-rich inner segments dissociate. Loss of these functional structures diminishes cone-dependent high-resolution central vision, which is utilized for most daily tasks. By transplanting wild-type rods, to restore glucose transport, or directly replacing glucose in the subretinal space, to bypass its retention in the RPE, we can regenerate cone functional structures, reactivating the dormant cells. Beyond providing metabolic building blocks for cone functional structures, we show glucose induces thioredoxin-interacting protein (Txnip) to regulate Akt signaling, thereby shunting metabolites toward aerobic glucose metabolism and regenerating cone OS synthesis.

Lutein and zeaxanthin toxicity with and without brilliant blue in rabbits

PURPOSE

To evaluate the safety profile of solutions containing lutein and zeaxanthin alone or associated with brilliant blue (BB).

METHODS

Twenty-eight New Zealand rabbits were used to evaluate 4 concentrations of the various dye solutions: 0.5% lutein/zeaxanthin; 0.5% lutein/zeaxanthin associated with 0.0125% BB; 0.3% lutein/zeaxanthin associated with 0.025% BB; and 0.25% lutein/zeaxanthin associated with 0.05% BB. The pHs of the dye solutions ranged from 6.5 to 7.2 and the osmolarities from 280 to 320 mOsm/mL. Each rabbit had 0.1 mL of one of the dyeing solutions injected into the vitreous cavity of the right eye, while balanced salt solution (BSS) was injected into the left eye as the control. Scotopic electroretinography responses were recorded in all eyes at different time points. The animals were sacrificed at 1 and 7 days after injection; the eyes were analyzed by light and transmission electron microscopy.

RESULTS

No significant (P>0.05) differences were seen in the a- and b-wave amplitudes among groups at any given point in time. Light and electron microscopy findings showed no significant abnormalities either, and were similar to the histological findings after intravitreal BSS injection.

CONCLUSIONS

Lutein and zeaxanthin alone or in association with BB showed a good safety profile in this experimental model.

The concentration-dependent effects of indocyanine green on retinal function in the electrophysiological ex vivo model of isolated perfused vertebrate retina

BACKGROUND

Dye solutions such as indocyanine green (ICG) are used for the staining of intraocular structures. The aim of the presented study was to investigate the effects of ICG on bovine retinal function using different concentrations of ICG.

METHODS

Bovine retina preparations were perfused with a standard solution and the electroretinogram was recorded. The nutrient solution was substituted by an ICG solution at varying concentrations for 45 min. Afterwards the preparations were reperfused with standard solution for at least 85 min.

RESULTS

Significant reductions in b-wave amplitude were found for concentrations of 0.0025% (p = 0.0099) and 0.025% (p = 0.0378). For the concentration of 0.025%, the b-wave amplitude remained significantly decreased (p = 0.0082) after the observation period, but a full recovery of the b-wave was observed for the concentration of 0.0025% (p = 0.1917).

CONCLUSION

Intraocular application of sufficient ICG concentrations for internal limiting membrane staining seems not possible without interfering with retinal function.

Progressive atrophy of retinal pigment epithelium after trypan-blue-assisted ILM peeling for macular hole surgery

We report a case of progressive atrophy of the retinal pigment epithelium (RPE) after trypan-blue-assisted peeling of internal limiting membrane (ILM) for macular hole surgery. A 68-year-old Caucasian female underwent a 20-g pars plana vitrectomy for a chronic stage-3 macular hole. The ILM was stained with 0.06% trypan blue (VisionBlue™, DORC Netherlands) for 2 min after fluid air exchange. Dye was reapplied for another 2 min due to poor staining. The ILM was completely removed around the macular hole with forceps. RPE atrophy was noticed at the edge of the hole 1 month after surgery. It progressively increased in intensity and enlarged over 2 years. Her final visual acuity was counting fingers, significantly worse compared to her presenting visual acuity of 20/200. Progressive atrophy of RPE in our patient was most likely due to the toxicity of trypan blue. Reapplication of the dye may increase the likelihood of toxicity.

A preliminary study of Heavy Brilliant Blue G for internal limiting membrane staining in macular hole surgery

Context:

Surgical outcomes of vitrectomy for idiopathic macular hole using a “heavy” Brilliant Blue G (HBBG) solution for staining and removal of the internal limiting membrane (ILM).

Settings and Design:

Prospective interventional case series conducted in a tertiary eye care hospital.

Materials and Methods:

Nineteen patients (20 eyes) with idiopathic macular hole were enrolled to undergo vitrectomy with ILM peeling using HBBG. BBG dye was made heavy by mixing with 10% dextrose normal saline (DNS) solution in 2:1 ratio. The adequacy of ILM staining was noted intraoperatively. The closure rates of macular hole and visual improvement were recorded. Patients were followed up postoperatively on day 1, week 1, and subsequently at 1, 3, and 6 months, and every 6th month thereafter.

Statistical Analysis:

Wilcoxon signed-rank test was used; P < 0.05 was considered significant.

Results:

Preoperative best-corrected visual acuity (BCVA) ranged from 20/1000 to 20/63 (median: 20/100). Intraoperatively, the ILM stained very well in all eyes, and was easily removed. All macular holes closed postoperatively. The mean follow-up was 6.15 ± 2 months (range: 4-10; median: 6 months). Final BCVA ranged from 20/20 to 20/80 (median: 20/40), amounting to a significant visual improvement (P = 0.0001). BCVA improved by 1-8 Snellen lines in 19 eyes (95%); 16 eyes (80%) improved by ≥2 lines; 13 eyes (65%) achieved a final BCVA of 20/40 or better.

Conclusions:

Addition of 10% DNS to BBG dye allowed good ILM staining with less dye during macular hole surgery, and provided excellent anatomic and visual outcomes.

Effect of vital dyes on retinal pigmented epithelial cell viability and apoptosis: implications for chromovitrectomy

PURPOSE

To investigate the in vitro effect of vital dyes on toxicity and apoptosis in a human retinal pigment epithelial cell line.

METHODS

ARPE-19 cells were exposed to brilliant blue (BBG), Evans Blue (EB), bromophenol blue (BroB), indocyanine green (ICG), infracyanine green (IfCG), light green (LG), fast green (FG), indigo carmine (IC) and Congo red (CR). Balanced salt solution was used as the control. Five different concentrations and 2 exposure times were tested. Cell viability was determined by the MTS (1-solution methyl thiazolyl tetrazolium) assay and apoptosis by Bax expression on Western blot.

RESULTS

All dyes significantly reduced cell viability after 3 min of exposure at all concentrations (p < 0.01), except for BBG that was safe at concentrations up to 0.25 mg/ml and CR up to 0.05 mg/ml, while LG was safe at all concentrations. Toxicity was higher after 30 min of exposure. Expression of Bax was upregulated after all dye exposures, except BBG; ICG had the highest Bax expression (p < 0.01).

CONCLUSIONS

Overall the safest dye was BBG followed by LG, IfCG, FG, CR, IC, BroB, EB and ICG. ICG was toxic at all concentrations and exposure times tested. Moreover, BBG was the only dye that did not induce apoptosis in ARPE-19 cells.

Staining properties of brilliant blue depending on different incubation times and solvents in humans

PURPOSE

Intravitreous injection of vital dyes, e.g. brilliant blue (BBG), promotes better visualization of the internal limiting membrane (ILM). This paper investigates the staining properties of BBG depending on different incubation times and 2 types of solvents--5% glucose (GL) or saline solution--in a prospective study in patients.

METHODS

This paper investigates various aspects of BBG in various methods. An interventional prospective study was conducted in patients to examine the binding properties of the blue dye diluted in either saline or 5% GL to epiretinal membranes (ERMs) and ILMs. Forty-nine consecutive patients older than 18 years scheduled for macular ERM, vitreomacular traction and macular hole surgeries were prospectively recruited. The primary outcomes of this study were the degree of ILM and ERM staining. The secondary outcomes of the study were the need of reinjection of BBG or any other dye, the ability of BBG to stain the vitreous, and frequency of complications. The staining of the ILM and ERM were graded as no staining, little, moderate or strong staining.

RESULTS

There was no correlation between age (p = 0.32) or gender (p = 0.33) in the staining affinity of BBG to either the ILM or ERM. BBG may be an appropriate staining agent for the ILM in the majority (82%) of surgeries; however, in approximately half of the cases (45%) surgeons considered BBG not enough for ERM coloring and visualization. There is a tendency of BBG to stain the ILM better when saline solution is used compared to GL 5%; however, this was not statistically significant (p = 0.64). There was no difference in the staining efficacy of BBG to the ERMs by either solution (p = 0.70), despite the low staining affinity.

CONCLUSION

BBG became the state-of-the-art dye for ILM identification. Differences in staining properties may imply that BBG should not be considered as first-line stain for ERM surgery. BBG is effective in ILM staining in over 80% of macular hole surgeries.

Assessment of retinal function before and after idiopathic macular hole surgery

PURPOSE

To evaluate preoperative and postoperative retinal function in patients who underwent macular surgery for idiopathic macular hole.

DESIGN

Prospective, comparative, interventional case series.

METHODS

Thirty eyes of 30 patients with idiopathic macular hole were included in the study. Patients underwent pars plana vitrectomy and peeling of the internal limiting membrane (ILM). ILM visualization was improved in 15 patients by using triamcinolone acetonide and in the remaining 15 patients by using infracyanine green dye. Spectral-domain optical coherence tomography examination was performed to document macular hole closure. Retinal function was assessed preoperatively and postoperatively over a period of 12 months by best-corrected visual acuity (BCVA) measurement (ETDRS chart), MP-1 microperimetry, and focal electroretinogram recording (fERG). Focal electroretinograms were recorded in response to a sinusoidally modulated (41 Hz), uniform field presented to the macular (18 degrees) and foveal (2.25 degrees) region.

RESULTS

Macular hole closure was achieved in all patients in both groups. At 12 months, visual acuity improved in both groups (P < .001), and there were no statistically significant differences between groups. Mean macular sensitivity within the central 2 and 8 degrees increased in both groups, and there were no statistically significant differences between groups at any follow-up. In the triamcinolone acetonide group, 12 months after surgery the amplitude of the fERG's first harmonic (1F) increased both in the macular region (P < .001) and in the foveal region (P < .05). In the infracyanine green group, at 12 months the amplitude of the first harmonic (1F) decreased in both areas. The decrease was significant in the macular region (P < .05) and not significant in the foveal region (P = .095).

CONCLUSION

Vitrectomy and ILM peeling assisted with either triamcinolone acetonide or infracyanine green staining improves visual acuity and mean macular sensitivity at 12 months in patients affected by idiopathic macular hole. However, triamcinolone acetonide staining is associated with an increase of fERG's first harmonic amplitude in the foveal and macular region, whereas in the case of infracyanine green staining it seems to decrease after surgery. The reduction of the amplitude of fERG's first harmonic suggests that infracyanine green may have a late toxic effect on photoreceptor cells.

Retinal pigmented epithelial cells cytotoxicity and apoptosis through activation of the mitochondrial intrinsic pathway: role of indocyanine green, brilliant blue and implications for chromovitrectomy

Purpose

To investigate the in vitro effect of four vital dyes on toxicity and apoptosis in a human retinal pigment epithelial (RPE) cell line.

Methods

ARPE-19 cells were exposed to brilliant blue (BriB), methyl blue (MetB), acid violet (AcV) and indocyanine green (ICG). Balanced salt solution was used as control. Five different concentrations of each dye (1, 0.5, 0.25, 0.05 and 0.005 mg/mL) and two exposure times (3 and 30 min) were tested. Cell viability was determined by cell count and MTS assay and cell toxicity by LDH assay. Real-time PCR and Western blotting were used to access the apoptosis process.

Results

ICG significantly reduced cell viability after 3 minutes of exposure at all concentrations (p<0.01). BriB was safe at concentrations up to 0.25 mg/mL and MetB at concentrations up to 0.5 mg/mL, while AcV was safe up to 0.05 mg/ml, after 3 minutes of exposure. Toxicity was higher, when the cells were treated for 30 minutes. Expression of Bax, cytochrome c and caspase-9 was upregulated at the mRNA and protein level after ICG exposure, while Bcl-2 was downregulated. AcV and MetB were similar to control. However, BriB resulted in upregulation of Bcl-2, an antiapoptotic protein.

Conclusions

The safest dye used on RPE cells was MetB followed by BriB and AcV. ICG was toxic at all concentrations and exposure times tested. Moreover, ICG was the only dye that induced apoptosis in ARPE-19 cells. BriB significantly increased Bcl-2 protein levels, which might protect against the apoptosis process.

Effects of light exposure, pH, osmolarity, and solvent on the retinal pigment epithelial toxicity of vital dyes

PURPOSE

To investigate the in vitro effect of pH, osmolarity, solvent, and light interaction on currently used and novel dyes to minimize dye-related retinal toxicity.

DESIGN

Laboratory investigation.

METHODS

Retinal pigment epithelium (RPE) human cells (ARPE-19) were exposed for 10 minutes to different pH solutions (4, 5, 6, 7, 7.5, 8, and 9) and glucose solutions (2.5%, 5.0%, 10%, 20%, 40%, and 50%) with osmolarity from 142 to 2530 mOsm, with and without 0.5 mg/mL trypan blue. R28 cells were also incubated with glucose (150, 310, and 1000 mOsm) and mannitol used as an osmotic control agent in both experiments. Dye-light interaction was assessed by incubating ARPE-19 for 10 minutes with trypan blue, brilliant blue, bromophenol blue, fast green, light green, or indigo carmine (0.05 mg/mL diluted in balanced saline solution) in the presence of high-brightness xenon and mercury vapor light sources.

RESULTS

Solutions with nonphysiologic pH, below 7 and above 7.5, proved to be remarkably toxic to RPE cells with or without trypan blue. Also, all glucose solutions were deleterious to RPE (P < .001) even in iso-osmolar range. No harmful effect was found with mannitol solutions. Among the dyes tested, only light green and fast green were toxic to ARPE-19 (P < .001). Light exposure did not increase RPE toxicity either with xenon light or mercury vapor lamp.

CONCLUSIONS

Solutions containing glucose as a dye solvent or nonphysiologic pH should be used with care in surgical situations where the RPE is exposed. Light exposure under present assay conditions did not increase the RPE toxicity.

The structural effect of intravitreal Brilliant blue G and Indocyanine green in rats eyes

PURPOSE

To compare the potential retinal toxicity of two commercially Brilliant blue G dyes (Brilliant Peel and Ocublue Plus) and Indocyanine green (ICG) at usual clinical concentration.

METHODS

Brilliant Peel 0.025% (n=9), Ocublue Plus 0.025% (n=9), and ICG 0.05% (n=9) were injected intravitreally into Sprague-Dawley rat left eyes with balanced salt solution injected in the contralateral eyes as control. Evaluation of the effect of the dyes on retinal architecture was done by histological analysis of neurosensory retinal thickness and retinal ganglion cell (RGC) counts 7 days after intravitreal injection. Paired t-test was done to detect the presence of biologically significant thinning in neurosensory retina and five retinal layers for each dye (paired t-tests). One-way ANOVA and Tukey's Honestly Significant Difference test were used to assess whether different dyes caused significant thinning in mean neurosensory retinal thickness and reduction of mean RGC density.

RESULTS

Eyes treated with ICG had significantly thinner mean total neurosensory retinal thickness compared with the control eyes (P-value=0.01), followed by those treated with Ocublue Plus (P-value=0.03). Brilliant Peel did not cause significant thinning in any of the five retinal layers (all P-values>0.05). No significant difference in mean thinning of the total retinal thickness was detected between dyes (P-value=0.11). The mean thickness of the photoreceptor outer segment and outer plexiform layers were significantly reduced in ICG-injected eyes when compared with the control eyes (P-value=0.02). No significant difference in mean thinning between the three dyes was detected at all five retinal layers using one-way ANOVA (all P-values>0.35). RGC density was significantly reduced for ICG (P-value=0.01) but only marginally for Ocublue Plus (P-value=0.05). No significant reduction in RGC density was observed for Brilliant Peel (P-value=0.2).

CONCLUSION

Intravitreal Brilliant Peel is safe to rats retina. The retinal thinning and reduction in RGC density induced by Ocublue Plus requires further studies to determine the safety profile of this product. Potential retinal toxicity is seen with ICG 0.05%.

Indocyanine green-assisted internal limiting membrane peeling in macular hole surgery: a meta-analysis

Background

The opinion of application of indocyanine green (ICG) in the macular hole surgery was contradictory. Here we conducted a meta-analysis to evaluate the effect of in internal limiting membrane (ILM) peeling for macular hole surgery.

Methods and Findings

We searched electronic databases for comparative studies published before July 2012 of ILM peeling with and without ICG. Twenty-two studies including 1585 eyes were included. Visual acuity (VA) improvement, including the postoperative rate of ≥20/40 VA gained (OR, 0.65; 95% CI, 0.43 to 0.97; P = 0.033) and increased LogMAR (WMD, −0.09; 95% CI, −0.16 to −0.02; P = 0.011), was less in the ICG group. The risk of visual field defects was greater in the ICG group than in the non-ICG group. There was no significant difference in the rate of anatomical outcomes between ILM peeling procedures performed with and without ICG. RPE changes and other postoperative complications were not significantly different between the ICG and non-ICG groups. An additional analysis showed that the VA improvement of the ICG group was less than the non-ICG group only within the first year of follow up. A subgroup analysis showed that the rate of VA improvement was lower in the ICG group than in other adjuncts group. A higher rate of secondary closure and less VA improvement were observed in a high proportion (>0.1%) of the ICG group. A sensitivity analysis after the randomized-controlled trials were excluded from the meta-analysis demonstrated no differences compared with the overall results.

Conclusions

This meta-analysis demonstrated that there is no evidence of clinical superiority in outcomes for ICG-assisted ILM peeling procedure over the non-ICG one. The toxicity of ICG should be considered when choosing the various staining methods.

Use of lutein and zeaxanthin alone or combined with Brilliant Blue to identify intraocular structures intraoperatively

PURPOSE

To determine whether a natural dye solution based on lutein and zeaxanthin alone or combined with Brilliant Blue stains and facilitates peeling of intraocular membranes in human eyes.

METHODS

In this study of 60 cadaveric eyes, open-sky vitrectomy including posterior hyaloid detachment was performed. Different lutein and zeaxanthin concentrations (0.01-20%) were tested alone or combined with different Brilliant Blue concentrations (0.0125-0.025%) in the corneal endothelium, corneal epithelium, anterior and posterior capsule, vitreous cavity through the macula including the posterior hyaloid, and internal limiting membrane. The various dye solutions were in contact with the intraocular membranes for <1 minute and then were removed by mechanical aspiration or membrane peeling initiated and completed with intraocular forceps. The specimens were examined by light and electron transmission microscopy.

RESULTS

Contact between lutein and zeaxanthin and the retinal, lens, and vitreous surface resulted in orange and greenish staining of the intraocular membranes, which facilitated surgical steps in all eyes. Lutein and zeaxanthin alone was useful for vitreous identification and lutein and zeaxanthin combined with Brilliant Blue had strong affinity for internal limiting membrane and anterior capsule. Light microscopy confirmed internal limiting membrane removal in all eyes tested. No dye solutions remained in the eyes after the membrane removal.

CONCLUSION

A natural dye solution based on lutein and zeaxanthin alone or combined with Brilliant Blue efficiently stained the anterior capsule, vitreous, and internal limiting membrane in human cadaveric eyes and may be a useful tool for vitreoretinal or cataract surgery.

In vivo, in vitro toxicity and in vitro angiogenic inhibition of sunitinib malate

PURPOSE

To evaluate the in vivo and in vitro toxicity of sunitinib malate, a multikinase inhibitor molecule.

DESIGN

Experimental, Prospective, Controlled.

METHODS

Human retinal pigment epithelial (ARPE-19) and human umbilical vein endothelialcells (HUVECS) were used in a culture toxicity test and exposed to different concentrations of sunitinib malate for 18 hours. The HUVECs also were cultured to evaluate the angiogenesis inhibitory effect of sunitinib malate. Fundus photography and angiographic, electrophysiologic, and histopathologic evaluations with light and electron microscopy were performed in two groups of five rabbits each that received different intravitreal concentrations of the drug. Each rabbit received 0.1 ml of sunitinib malate in the right eye (one group with 12.5 mg/ml, the other group with 25 mg/ml); all animals received 0.1 ml of physiologic saline solution in the left eye. After sacrifice, the eyes were enucleated and fixed with modified Karnovsky solution.

RESULTS

No toxicity related to sunitinib malate was observed using an in vitro model with the 12.5 and 25 mg/ml solutions in HUVEC and ARPE cell cultures. No toxicity was observed in the in vivo model with 12.5 mg/ml, but light microscopy showed that the 25 mg/ml solution damaged the photoreceptors layer. No functional changes in the electroretinogram were observed in any group.

CONCLUSIONS

Sunitinib malate 12.5 mg/ml caused no toxicity in in vivo and in vitro models, but the 25 mg/ml concentration caused retinal changes suggesting toxicity in the in vivo model. Further research with the drug is needed in models of ocular neovascularization.

A comparison of brilliant blue G, trypan blue, and indocyanine green dyes to assist internal limiting membrane peeling during macular hole surgery

PURPOSE

To compare surgical outcomes with three dyes, brilliant blue G (BBG), trypan blue (TB) and indocyanine green (ICG), used to facilitate internal limiting membrane peeling during macular hole surgery.

METHODS

This comparative, interventional cases series consisted of 50 eyes of 50 patients with senile idiopathic macular holes, who underwent vitrectomy with internal limiting membrane peeling using BBG (n = 15), TB (n = 20), or ICG (n = 15). The cases involving use of BBG and TB were enrolled prospectively and concurrently, and the cases using ICG were selected through chart reviews. We compared the intraoperative surgical facilitation with the 3 dyes and the surgical outcomes in terms of macular hole closure and visual improvement at 6 months.

RESULTS

The 3 groups were similar in mean age, sex distribution, preoperative best-corrected visual acuity, and duration of follow-up (P = 0.957, 0.974, 0.939, and 0.5524, respectively). Of the 3 dyes, BBG appeared to provide greatest intraoperative facilitation: most convenient to use and remove, and similar to ICG in terms of internal limiting membrane staining. Six months postoperatively, macular hole closed in 100%, 95%, and 86% eyes (P = 0.48) and visual improvement occurred in 80%, 85%, and 33% eyes (P = 0.005) in BBG, TB, and ICG groups, respectively. The BBG and TB groups also had a better final best-corrected visual acuity than ICG group (P = 0.05) and smaller percentage of visual decline (5% and 6.7% vs. 40% respectively; P = 0.049).

CONCLUSION

Brilliant blue G was comparable with TB in optimizing visual and functional outcomes, while it was similar to ICG in ease of internal limiting membrane peeling.

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.

Functional and structural effect of intravitreal indocyanine green, triamcinolone acetonide, trypan blue, and brilliant blue g on rat retina

PURPOSE

The purpose of this study was to evaluate the functional and structural damage of the retina after intravitreal injections of four different dyes in the rat.

METHODS

Rats were injected intravitreally with indocyanine green (ICG), trypan blue, triamcinolone acetonide, or brilliant blue G in the right eye. The other eye was injected with saline and served as a control. Simultaneous bilateral electroretinograms were recorded before injection and 7 and 28 days after injection. Histology and immunohistochemistry analyses with antibodies recognizing glial fibrillary acidic protein and protein kinase C were performed 28 days after the initial injection on both eyes.

RESULTS

Seven days after dye injection, the electroretinogram response of the treated eyes was altered in each group. At 1 month, eyes injected with triamcinolone acetonide, trypan blue, or brilliant blue G fully recovered, whereas eyes treated with ICG had A-wave and B-wave reduction of 65% and 63%, respectively. The inner nuclear layer thickness was statistically decreased in the ICG group (P = 0.003) but not with other dyes. Protein kinase C staining was decreased in the ICG group only, but no abnormal qualitative staining was found with either glial fibrillary acidic protein or protein kinase C antibodies with any dye.

CONCLUSION

Among the four tested dyes, only ICG led to functional and structural retinal damage.

Subretinal migration of trypan blue during macular hole and epiretinal membrane peel: an observational case series. Is there a safer method?

PURPOSE

To report the inadvertent subretinal migration and effect of trypan blue (TB) during staining of the epiretinal membrane (ERM) for macular pucker, and internal limiting membrane during macular hole (MH) surgery, and to suggest alternative safe methods of injecting TB.

METHODS

Three cases in which TB migrated to the subretinal space were followed up on day 1, day 7, day 21, and at 3 months following the initial operation. Two of the cases were operated for MH and one patient had ERM peel. Colour fundus and optical coherence tomography (OCT) were performed on day 1 and on each subsequent visit.

RESULTS

In both cases of MH the hole was closed postoperatively. The patient with ERM had the membrane peeled successfully as documented by OCT. Clinically, all patients demonstrated chorioretinal atrophy in the area of TB migration. There was thinning of the retina as noted by OCT.

CONCLUSION

It is difficult to prove whether the chorioretinal atrophy was caused by the subretinal TB or by the accidental forceful dye injection, but subretinal TB and contact of TB with the retinal pigment epithelium should be avoided, and precautions should be taken during intravitreal injection. We suggest a more controlled method of dye injection in such cases using the flute needle rather than the syringe technique that is conventionally used.

Dyes in ocular surgery: principles for use in chromovitrectomy

PURPOSE

To present the current state-of-the-art information regarding the properties, indications, surgical techniques, and toxic effects of current and past applications of vital dyes in chromovitrectomy.

DESIGN

Critical analysis and surgical perspective of the literature and recent studies.

METHODS

Review, interpretation, and commentary regarding the most relevant experimental as well as clinical studies including the authors' clinical and laboratory research.

RESULTS

There is a consensus that the application of vital dyes facilitates the delicate removal of intraocular membranes during vitreoretinal surgery. Controversy still remains around various issues, mainly potential toxicity and safety. There is room for further investigation of novel and specific vital dyes. Dyes such as Evans blue and light green may stain the internal limiting membrane very well, whereas fast green and indigo carmine may be very safe to the retina. However, comparing the staining and toxicity data has revealed that Bromophenol blue and Brilliant blue may be even better novel agents. The dyes currently used for different steps in chromovitrectomy are: triamcinolone acetonide for vitreous identification; indocyanine green, infracyanine green, and Brilliant blue for internal limiting membrane identification; and Trypan blue for epiretinal membrane identification.

CONCLUSIONS

Clear-cut safety profiles for the different dyes in chromovitrectomy have not yet been established, and current state-of-the-art staining-assisted procedures should be performed using concentrations and volumes as low as possible.

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.