The Use of Vital Dyes in Ocular Surgery

Snip conjunctivoplasty associated with methylene blue staining for treatment of postoperative conjunctival chemosis

Conjunctival chemosis usually undergoes spontaneous resolution; sometimes, it requires treatment. We present the case of a 43 years-old female patient who developed bilateral conjunctival chemosis following upper and lower blepharoplasty. Two months after the operation, patient underwent bilateral snip conjunctivoplasty with methylene blue demarcation of the chemotic conjunctiva.

Molecular and cellular imaging of the eye

The application of molecular and cellular imaging in ophthalmology has numerous benefits. It can enable the early detection and diagnosis of ocular diseases, facilitating timely intervention and improved patient outcomes. Molecular imaging techniques can help identify disease biomarkers, monitor disease progression, and evaluate treatment responses. Furthermore, these techniques allow researchers to gain insights into the pathogenesis of ocular diseases and develop novel therapeutic strategies. Molecular and cellular imaging can also allow basic research to elucidate the normal physiological processes occurring within the eye, such as cell signaling, tissue remodeling, and immune responses. By providing detailed visualization at the molecular and cellular level, these imaging techniques contribute to a comprehensive understanding of ocular biology. Current clinically available imaging often relies on confocal microscopy, multi-photon microscopy, PET (positron emission tomography) or SPECT (single-photon emission computed tomography) techniques, optical coherence tomography (OCT), and fluorescence imaging. Preclinical research focuses on the identification of novel molecular targets for various diseases. The aim is to discover specific biomarkers or molecular pathways associated with diseases, allowing for targeted imaging and precise disease characterization. In parallel, efforts are being made to develop sophisticated and multifunctional contrast agents that can selectively bind to these identified molecular targets. These contrast agents can enhance the imaging signal and improve the sensitivity and specificity of molecular imaging by carrying various imaging labels, including radionuclides for PET or SPECT, fluorescent dyes for optical imaging, or nanoparticles for multimodal imaging. Furthermore, advancements in technology and instrumentation are being pursued to enable multimodality molecular imaging. Integrating different imaging modalities, such as PET/MRI (magnetic resonance imaging) or PET/CT (computed tomography), allows for the complementary strengths of each modality to be combined, providing comprehensive molecular and anatomical information in a single examination. Recently, photoacoustic microscopy (PAM) has been explored as a novel imaging technology for visualization of different retinal diseases. PAM is a non-invasive, non-ionizing radiation, and hybrid imaging modality that combines the optical excitation of contrast agents with ultrasound detection. It offers a unique approach to imaging by providing both anatomical and functional information. Its ability to utilize molecularly targeted contrast agents holds great promise for molecular imaging applications in ophthalmology. In this review, we will summarize the application of multimodality molecular imaging for tracking chorioretinal angiogenesis along with the migration of stem cells after subretinal transplantation in vivo.

Advances in Vitreoretinal Surgery

Advances in vitreoretinal surgery provide greater safety, efficacy, and reliability in the management of the several vitreoretinal diseases that benefit from surgical treatment. The advances are divided into the following topics: scleral buckling using chandelier illumination guided by non-contact visualization systems; sclerotomy/valved trocar diameters; posterior vitrectomy systems and ergonomic vitrectomy probes; chromovitrectomy; vitreous substitutes; intraoperative visualization systems including three-dimensional technology, systems for intraoperative optical coherence tomography, new instrumentation in vitreoretinal surgery, anti-VEGF injection before vitrectomy and in eyes with proliferative diabetic retinopathy, and new surgical techniques; endoscopic surgery; the management of subretinal hemorrhages; gene therapy; alternative techniques for refractory macular hole; perspectives for stem cell therapy and the prevention of proliferative vitreoretinopathy; and, finally, the Port Delivery System. The main objective of this review is to update the reader on the latest changes in vitreoretinal surgery and to provide an understanding of how each has impacted the improvement of surgical outcomes.

Questions about Residual Cell Viability in Cryopreserved Human Amniotic Membrane and Its Impact on Clinical Applications

We questioned the relevance of evaluating residual cell viability in human amniotic membrane (hAM) after its cryopreservation since cell survival is controversial and its ability to act as a matrix (including the presence of growth factors and cytokines) appears to be most important for tissue regeneration purposes. We also discussed the usefulness of osteodifferentiating amniotic cells in whole hAM for bone repair applications. We have evidence that determining residual cell viability after cryopreservation and hAM osteodifferentiation is not justified.

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.

XEN Gel Staining with Trypan Blue: A Simple and Effective Technique to Improve Device Visualization during Implantation

The Xen Gel Stent (Allergan, Irvine, CA, USA) is a hydrophilic collagen-based gelatin tube of 6 mm in length which creates a channel of communication between the anterior chamber and the subconjunctival space allowing aqueous humor outflow. XEN is an ab interno, minimally invasive, glaucoma surgery device which has a better safety profile and offers a less invasive way of lowering intraocular pressure. Unfortunately, one of its weaknesses is that visualization of the implant during surgery is difficult, and this difficulty may be exacerbated, for instance, by a subconjunctival hemorrhage. The purpose of this paper is to describe a simple and effective technique for improving device visualization (XEN 45 μm) during the implantation. How to cite this article: Ramovecchi V, Franco F, Barbera GR. XEN Gel Staining with Trypan Blue: A Simple and Effective Technique to Improve Device Visualization during Implantation. J Curr Glaucoma Pract 2021;15(3):161-163.

Preoperative imaging optimized for epiretinal membrane surgery

Background

To compare imaging modalities for visualizing primary epiretinal membrane (ERM) with each other and with intraoperative digital images (IDI) after blue staining.

Methods

The records of consecutive patients operated for primary ERM over a 12-month period were retrospectively reviewed. Preoperative imaging included color fundus photography (CFP), En Face spectral-domain optical coherence tomography (OCT), 45° infrared- (IR) and blue-reflectance (BR) scanning laser ophthalmoscopy. All images were qualitatively analyzed and scored from 0–4 according to the ability to visualize ERM details (0 = no visible ERM or vessel contraction, 1 = vessel contraction, 2 = retinal folds, 3 = ERM limits, 4 = elevated ERM edge). The preoperative ERM morphology was then compared to that seen on the IDI acquired after 1-min blue dye staining when available.

Results

Seventy eyes were included. The highest score for ERM visualization was obtained on BR and En Face OCT. A score of 3 or 4 was obtained in 68.5%, 62.1%, 17.9% and 13.6% of cases on En Face OCT, BR, CFP and IR images, respectively. IDI were available for 20 eyes, and showed a similar ERM morphology compared to preoperative images in most cases: a negative staining pattern corresponded to a plaque on En face OCT in 91% of eyes. However, IDI failed to show the ERM edges in 37.5% of cases.

Conclusion

ERM morphology was better visualized preoperatively by BR and En Face OCT, in a similar way to the IDI after staining. Future intraoperative visualization systems could integrate both imaging modalities overlaid with the IDI for guiding ERM removal instead of staining.

Role of Vital Dyes in Chromovitrectomy

ABSTRACT

Chromovitrectomy, the intraocular application of dyes to assist visualization of preretinal tissues during vitreoretinal surgery, was introduced to avoid ocular complications related to internal limiting membrane peeling, inadequate removal of the vitreous, and incomplete removal of epiretinal membranes. Since 2000, chromovitrectomy has become a popular approach among vitreoretinal specialists. The first vital dye used in chromovitrectomy, indocyanine green, facilitated identification of the fine and transparent internal limiting membrane. Following indocyanine green, trypan blue was introduced to identify epiretinal membranes, and triamcinolone acetonide stained the vitreous well. Recently, additional natural dyes such as lutein and anthocyanin from the açaí fruit have been proposed for intraocular application during vitrectomy. The main goal of this review was to study the role of vital stains in chromovitrectomy and report the latest findings in the literature.

The effects of vıtal dyes on mechanıcal propertıes of the human anterıor lens capsule

Purpose:

The purpose of this study was to evaluate the mechanical effects of vital dyes on the anterior lens capsule via the nanoindentation method.

Methods:

Twenty anterior lens capsules of 20 different patients were dissected into four equal fragments. Each fragment was stained separately with dyes for intraocular surgeries, such as trypan blue 0.06% (TB), brilliant blue 0.025% (BB), and indocyanine green 0.05% (ICG), for 1 min. The remaining fragment was assessed as an untreated control group. The alterations on the mechanical characteristics of the anterior lens capsule were evaluated using a nanoindentation testing device with Oliver–Pharr and Martens hardness methods.

Results:

The mean values of elasticity were 7.842 ± 0.55 GPa for capsules fragments stained with TB (P < 0.05), 8.407 ± 0.82 GPa for capsules fragments stained with BB (P < 0.05), 8.557 ± 0.60 GPa for ICG (P < 0.05), and 6.09 ± 0.57 GPa for the untreated control group. The mean values of stiffness were 299.7 ± 47 MPa for TB (P < 0.05), 317.9 ± 34 MPa for BB (P < 0.05), 331.8 ± 48 MPa for ICG (P < 0.05), and 229.85 ± 44 MPa for the untreated control group. The elasticity of the capsules statistically decreased in comparison to the control group, and the capsule stiffness showed a statistically significant increase in comparison to the untreated controls.

Conclusion:

The mechanical characteristics of the human anterior lens capsule were affected in association with the alterations in the elasticity and stiffness properties of the capsule as a result of exposure to three different dyes.

New Brilliant Blue G Derivative as Pharmacological Tool in Retinal Surgery

Our study was aimed at assessing the retinal binding of a new synthetic Brilliant Blue G (BBG) derivative (pure benzyl-Brilliant Blue G; PBB) ophthalmic formulation, to improve vitreoretinal surgery procedure. Protein affinity of the new molecule was evaluated in vitro (cell-free assay) and in silico. Furthermore, an ex vivo model of vitreoretinal surgery was developed by using porcine eyes to assess the pharmacological profile of PBB, compared to commercial formulations based on BBG and methyl-BBG (Me-BBG). PBB showed a higher affinity for proteins (p < 0.05), compared to BBG and Me-BBG. In vitro and in silico studies demonstrated that the high selectivity of PBB could be related to high lipophilicity and binding affinity to fibronectin, the main component of the retinal internal limiting membrane (ILM). The PBB staining capabilities were evaluated in porcine eyes in comparison with BBG and Me-BBG. Forty microliters of each formulation were slowly placed over the retinal surface and removed after 30 s. After that, ILM peeling was carried out, and the retina collected. BBG, Me-BBG, and PBB quantification in ILM and retina tissues was carried out by HPLC analysis. PBB levels in the ILM were significantly (p < 0.05) higher compared to BBG and Me-BBG formulations. On the contrary, PBB showed a much lower (p < 0.05) distribution in retina (52 ng/mg tissue) compared to BBG and Me-BBG, in particular PBB levels were significantly (p < 0.05) lower. Therefore, the new synthetic Brilliant Blue derivative (PBB) showed a great ILM selectivity in comparison to underneath retinal layers. In conclusion, these findings had high translational impact with a tangible improving in ex vivo model of retinal surgery, suggesting a future use during surgical practice.

Determination of trypan blue efficacy in the mitigation of ex vivo canine PCO formation

PURPOSE

To determine whether trypan blue (TB) reduces canine lens epithelial cell (LEC) or corneal endothelial cell (CEC) viability in vitro; if cell death is noted, to subsequently evaluate the molecular mechanism.

METHODS

Cellular viability was determined using a lactate dehydrogenase (LDH) assay. In TB-treated LECs, caspase 3/7 activity was assessed to evaluate apoptosis; autophagy was evaluated using immunoblotting against LC3 and p62. To evaluate the effects of TB on ex vivo posterior capsule opacification (PCO), following mock cataract surgery, lens capsules were treated with TB and subsequently maintained in culture to determine LEC migration and proliferation.

RESULTS

Following acute exposure, TB did not significantly reduce LEC or CEC viability at any of the concentrations tested. Increased caspase 3/7 activity was found in LEC cultures treated with TB for an extended period of time; no change in LC3 or p62 expression was noted. Ex vivo PCO formation was not significantly altered by TB treatment.

CONCLUSIONS

Acute exposure to TB did not reduce LEC or CEC viability, and only longer exposure to TB was able to initiate apoptosis. Treatment with intraocular TB at the time of cataract surgery is likely safe to the CECs but will not prevent PCO formation.

A new dye based on anthocyanins from the acai fruit (Euterpe oleracea) for chromovitrectomy in humans: clinical trial results

PURPOSE

To test the applicability of the acai dye at a 25% concentration for identifying the posterior hyaloids and internal limiting membranes (ILMs) during pars plana vitrectomy (PPV) in human eyes with macular holes (MHs).

METHODS

This study included 25 patients with chronic idiopathic MHs. The exclusion criteria included glaucoma, previous significant ocular conditions, and previous ocular surgeries except uncomplicated cataract. Ten surgeons performed 23-gauge four-port PPV, phacoemulsification, posterior hyaloid detachment, ILM peeling guided by dye staining, and perfluoropropane injection. The patients remained prone for 5 days postoperatively. The patients were evaluated postoperatively after 1, 30, and 180 days. The surgeons completed a questionnaire regarding the dye's staining abilities.

RESULTS

The posterior hyaloids and ILMs stained purple in all eyes. The final best-corrected visual acuity improved significantly (p < 0.001) from preoperatively (1.37 ± 0.29) to 180 days postoperatively (1.05 ± 0.43). The MHs closed in 76% of eyes.

CONCLUSION

The acai dye at a 25% concentration identified posterior hyaloids and ILMs during PPVs in humans. Dye toxicity was unlikely.

Evaluation of Patent Blue as the Vital Dye in an Animal Model of Descemet Membrane Endothelial Keratoplasty

PURPOSE

To evaluate the safety and feasibility of patent blue (PB) as the vital dye in Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Bovine corneal endothelial cells were incubated with different concentrations (0.02%-2.5%) of PB. The cell viability, which was assessed by Cell Counting Kit-8 assay, was compared with that of untreated control and 0.06% to 0.4% trypan blue. The dyes were also used for graft preparation and implantation in the porcine eye model to evaluate stain quality, dye retention, and the feasibility of using PB in DMEK surgery.

RESULTS

No obvious increase in cytotoxicity was detected for 0.06% to 0.4% trypan blue and PB at concentrations up to 1.0%, but the cell viability after incubating with 1.5% to 2.5% PB was significantly reduced. PB at 0.5% to 1.0% generated good staining quality that can be used to facilitate graft implantation. Although the staining quality of 0.5% to 1.0% PB faded to an intermediate level after a 30-minute wash in phosphate-buffered saline, dye retention persisted for up to 24 hours.

CONCLUSIONS

PB at 0.5% to 1.0% is biocompatible and can stain the graft sufficiently, making it an alternative for DMEK surgery.

Cataracts

An estimated 95 million people worldwide are affected by cataract. Cataract still remains the leading cause of blindness in middle-income and low-income countries. With the advancement of surgical technology and techniques, cataract surgery has evolved to small-incisional surgery with rapid visual recovery, good visual outcomes, and minimal complications in most patients. With the development of advanced technology in intraocular lenses, the combined treatment of cataract and astigmatism or presbyopia, or both, is possible. Paediatric cataracts have a different pathogenesis, surgical concerns, and postoperative clinical course from those of age-related cataracts, and the visual outcome is multifactorial and dependent on postoperative visual rehabilitation. New developments in cataract surgery will continue to improve the visual, anatomical, and patient-reported outcomes. Future work should focus on promoting the accessibility and quality of cataract surgery in developing countries.

Impact of Vital Dyes on Cell Viability and Transduction Efficiency of AAV Vectors Used in Retinal Gene Therapy Surgery: An In Vitro and In Vivo Analysis

Purpose

Treatment of inherited retinal degenerations using adeno-associated viral (AAV) vectors involves delivery by subretinal injection. In the latter stages, alteration of normal anatomy may cause difficulty in visualizing the retinotomy, retinal detachment extension, and vector diffusion. Vital dyes may be useful surgical adjuncts, but their safety and impact on AAV transduction are largely unknown.

Methods

The effects of Sodium Fluorescein (SF), Membrane Blue (MB), and Membrane Blue Dual (DB) at a range of dilutions were assessed on human embryonic kidney cells in vitro using an AAV2-green fluorescent protein (GFP) reporter at different multiplicities of infection. Flow cytometry analysis was performed to assess both cell viability and transduction efficiency. The effect on quantitative (q)PCR titer was determined. Balanced salt solution (BSS) or dilute DB (1:5 in BSS) were delivered subretinally into left/right eyes of C57BL/6J mice (n = 12). Retinal structure and function were analyzed by optical coherence tomography, autofluorescence, dark-and light-adapted full-field electroretinography.

Results

DB and MB were not toxic at any concentration tested, SF only when undiluted. The presence of dyes did not adversely affect the genomic titer. DB even increased the values, due to presence of surfactant in the formulation. AAV2-GFP transduction efficiency was not reduced by the dyes. No structural and functional toxic effects were observed following subretinal delivery of DB.

Conclusions

Only undiluted SF affected cell viability. No effects on qPCR titer and transduction efficiency were observed. DB does not appear toxic when delivered subretinally and improves titer accuracy. DB may therefore be a safe and helpful adjunct during gene therapy surgery.

Translational Relevance

This paper might be of interest to the retinal gene therapy community: it is a “bench to bedside” research paper about the potential use of dyes as a surgical adjunct during the gene therapy surgery. We have tested the potential toxicity and impact on transduction efficiency in an in vitro and in vivo model.

Chandelier Illumination for Descemet Membrane Endothelial Keratoplasty

PURPOSE

To describe a simple technique that uses posterior chandelier illumination during Descemet membrane endothelial keratoplasty in cases of severe bullous keratopathy (BK).

METHODS

Five eyes of 4 patients with advanced BK undergoing Descemet membrane endothelial keratoplasty were retrospectively analyzed. The pupil of the host eye was not treated with mydriatic or miotic agents. The chandelier illuminator was inserted transconjunctivally into the vitreous cavity from the pars plana.

RESULTS

In all eyes, BK was secondary to laser iridotomy, which was performed for prevention or treatment of angle closure glaucoma. The implanted graft was clearly confirmed in the anterior chamber using activated chandelier illumination. The graft was immediately attached to the host cornea, with eventual healing of BK in all eyes. No complication involving insertion or removal of the 25-gauge trocar and the chandelier illuminator was observed. No vision-threatening complication was observed in any of the 5 eyes.

CONCLUSIONS

The chandelier illuminator provided good visibility of the anterior chamber and enhanced the safety of surgery by preventing formation of an inverted graft.

Microvascular changes after vitrectomy with internal limiting membrane peeling: an optical coherence tomography angiography study

PURPOSE

To evaluate superficial capillary plexus (SCP) changes occurring after internal limiting membrane (ILM) peeling for the treatment of idiopathic epiretinal membrane (ERM).

METHODS

A total of 15 eyes of 15 patients affected by idiopathic ERM (eight males and seven females; mean age 59.8 ± 9.6 years) were enrolled in the study. Patients were treated with pars plana vitrectomy followed by ERM and ILM peeling. Subjects were evaluated at baseline and at the week-1 and month-1 follow-up visits. At each visit, patients were evaluated with a complete ophthalmologic evaluation, which included imaging with optical coherence tomography angiography.

RESULTS

Overall, the SCP vessel density was 43.0 ± 3.0% at baseline and was stable throughout the follow-up (40.0 ± 4.0% at week-1 and 41.0 ± 4.0% at month-1 follow-up visits; p = 0.087 and p = 0.426, respectively). Nevertheless, the SCP vessel density was reduced at week-1 visit in both the superior and inferior sectors. In these sectors, the superficial vessel density was still reduced at the month-1 follow-up visit.

CONCLUSIONS

We observed a reduction in the SCP vessel density occurring after pars plana vitrectomy with ILM peeling. The reduction is referred to those areas where other changes (e.g., swelling of the arcuate nerve fiber layer) have been already described. In theory, superficial vessel density modifications may be due to the direct surgical trauma to the inner retina, where the superficial plexus is contained, during the ILM grasping.

Use of Brilliant Blue G in Descemet's Membrane Endothelial Keratoplasty

Vital staining of the endothelial graft is essential during Descemet's membrane endothelial keratoplasty (DMEK) to ensure surgical success. DMEK surgeons worldwide commonly use trypan blue (TB) to this end. However, TB may exert toxic effects on both the cornea and retina. Recently, Brilliant Blue G (BBG) has become recognized as an alternative stain for use during vitreoretinal surgery; BBG is associated with lower levels of toxicity. We retrospectively analyzed the utility of BBG staining during DMEK. We used 0.1% (w/v) BBG to stain the DMEK grafts of 12 patients. We evaluated the best spectacle-corrected visual acuity (BSCVA), central corneal thickness (CCT), and endothelial cell density (ECD) before and 3 and 6 months after surgery. BBG was effective in terms of graft visualization during DMEK. The BSCVA (log  MAR) improved from 0.99 ± 0.57 to 0.01 ± 0.07 (p < 0.05). The CCT decreased from 720.3 ± 58.1 μm preoperatively to 511.5 ± 50.6 μm at 6 months postoperatively (p = 0.0001). The ECD decreased from 2,754 ± 296 cells/mm² to 1,708 ± 426 cells/mm² at 6 months postoperatively (p < 0.001). The ECD loss was 37.9 ± 16.3%. The outcomes using BBG were comparable to those of earlier reports that employed TB; thus, BBG may be a viable alternative to TB.

Retinal Toxicity of Acai Fruit (Euterpe Oleracea) Dye Concentrations in Rabbits: Basic Principles of a New Dye for Chromovitrectomy in Humans

PURPOSE

Evaluate toxicity of acai fruit (Euterpe oleracea) dye concentrations in a rabbit model.

METHODS

Rabbits were injected intravitreously with 10%, 25%, and 35% acai dye concentrations. Control eyes received balanced salt solution (BSS). Electroretinogram (ERG), fundus imaging, fluorescein angiography (FA), optical coherence tomography (OCT), and light and transmission electron microscopy (LM/TEM) were performed.

RESULTS

Fundus imaging showed increased vitreous opacity with increased dye concentrations. FA and OCT showed normality with all concentrations. Comparisons between BSS and dye concentrations were analyzed using Kruskal-Wallis and Mood's median test (p < 0.05). At 24 h, ERGs showed reduced amplitudes from baseline in all eyes. Median b-wave amplitudes nonsignificantly decreased and latency increased with 10% and 25%; findings were significant (p < 0.05) for 35%. LM and TEM showed no abnormalities for 10% and 25%. With 35%, TEM showed ganglion cell edema at 24 h that resolved after 7 days. Vacuolization, multilamellar bodies, and nerve bundle damage occurred at 24 h/7 days in the inner nuclear layer. Mitochondrial cristae disruption occurred in the inner photoreceptor segment at 24 h that decreased by 7 days.

CONCLUSION

Ten and twenty-five percent concentrations were safe and may improve identification of the posterior hyaloid and internal limiting membrane during chromovitrectomy in humans.

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.

COMPARATIVE EVALUATION OF SEQUENTIAL INTRAOPERATIVE USE OF WHOLE BLOOD FOLLOWED BY BRILLIANT BLUE VERSUS CONVENTIONAL BRILLIANT BLUE STAINING OF INTERNAL LIMITING MEMBRANE IN MACULAR HOLE SURGERY

PURPOSE

To compare the structural and functional outcome of use of autologous heparinized whole blood before staining internal limiting membrane with brilliant blue (BB) versus conventional BB-assisted macular hole surgery.

METHODS

Sixty eyes of 60 patients were randomly divided equally in Group A (BB staining using whole blood) and Group B (conventional BB staining). Clinical assessment and spectral domain optical coherence tomography was done at baseline and 3 weeks, 6 weeks, 16 weeks, and 6 months postoperatively.

RESULTS

Group A eyes had a significantly higher best-corrected visual acuity as compared with Group B postoperatively (P < 0.001, <0.001, 0.004, 0.04 at 3, 6, 16 weeks, and 6 months). Inner segment/outer segment junction continuity was noted in greater number of eyes in Group A compared with Group B (P = 0.02, 0.002, 0.003, and 0.03 at 3, 6, 16 weeks, and 6 months). Eyes in Group A had significantly higher outer foveal thickness at 3 weeks (P = 0.001) and 6 weeks (P < 0.001) compared with Group B.

CONCLUSION

Use of whole blood before staining internal limiting membrane with BB causes earlier and better visual rehabilitation postoperatively, which could be attributed to earlier photoreceptor regeneration as evidenced by inner segment/outer segment junction continuity and increase in outer foveal thickness.

XEN Gel Stent Early Failure-dye-enhanced Ab-externo Revision

The XEN gel stent is an ab-interno minimally invasive glaucoma surgery device that reduces intraocular pressure by creating a subconjunctival drainage pathway. XEN intents to provide a safer and less invasive mean of lowering intraocular pressure. As with any new device, there is still some lack of experience and knowledge concerning efficacy, technique, and complications. We report a novel surgical approach for early bleb failure after XEN implantation.

How to cite this article

Ferreira NP, Pinto JM, Teixeira F, Pinto LA. XEN Gel Stent Early Failure-dye-enhanced Ab-externo Revision. J Curr Glaucoma Pract 2018;12(3):139-141.

Osmolarity and spectrophotometric property of brilliant blue green define the degree of toxicity on retinal pigment epithelial cells exposed to surgical endoilluminator

Objective

To evaluate the effect of varying concentrations of brilliant blue green (BBG) and their different biochemical characteristics on retinal pigment epithelial (RPE) cells under xenon light source illumination at varying distances to identify safe parameters for intraoperative use.

Methods

Human retinal RPE cells (ARPE-19) were exposed to two concentrations (0.25 and 0.50 mg/mL) of BBG and illuminated with a xenon surgical illuminator at varying distances (10 and 25 mm), intensity levels, and time intervals (1, 5, and 15 minutes). Additionally, the effect of osmolarity was examined by diluting BBG in different concentrations of glucose. Cytotoxicity of BBG and osmolarity effects on cell viability were evaluated using a WST-1 assay. Light absorption and emission characteristic of BBG in different solvents were measured using a plate reader at different wavelengths. Lastly, the activity of caspase-3 was also studied.

Results

Cell viability of ARPE-19 cells was 77.4%±12.7%, 78.7%±17.0%, and 65.0%±19.7% at 1, 5, and 15 minutes to exposure of high illumination xenon light at 10 mm (P<0.05) compared to controls. At both distances of illumination (10 and 25 mm), similar cell viabilities were seen between 1 and 5 minutes of exposure. However, there was a decline in viability when the illumination was carried out to 15 minutes in all groups (P<0.05). There was no significant reduction in cell viability in presence or absence of xenon light in different osmolar solutions concentrations of glucose (P>0.05). Maximal light absorption of BBG was noted between 540 and 680 nm. Activated caspase-3 level was not significant in both the concentrations of BBG (P>0.05).

Conclusion

Our findings suggest that BBG at 0.25 mg/mL during vitreoretinal surgery is safe and not toxic to RPE cells up to 5 minutes under focal high illumination (10 mm) and up to 15 minutes under medium diffuse illumination (25 mm). BBG was safe to be mixed with isotonic glucose solution at the concentration range of 2.5%–10%, regardless of the illumination status.

Effects of intracameral brilliant blue on the corneal endothelium of swine: in vitro study

Abstract: The aim was to investigate the ultrastructural changes in the corneal endothelium of pigs induced by intracameral 0.05% brilliant blue. Twenty swine corneas were separated into two groups, the right eye bulbs (control group) and the left eye bulbs (experimental group) of the same animal. All the eye bulbs were evaluated with specular microscopy. The cornea of the right eye bulbs was excised and in the left eye bulbs 0.2ml of 0.05% brilliant blue vital dye (OPTH-blue±) was injected into the anterior chamber, where it remained for one minute. Then the anterior chamber was cleaned with a balanced salt solution injection and the cornea was excised too. All the corneas were evaluated by scanning electron microscopy to evaluate the changes on the endothelium caused by the brilliant blue dye. There were no significant differences between the right corneal endothelium cells and the left corneal endothelium cells with scanning electron microscopy after intracameral use of 0.05% brilliant blue dye. The 0.05% brilliant blue dye concentration did not cause deleterious effects for the swine corneal endothelium after intracameral use and can be a choice for safe staining of the anterior capsule of the lens in cataract surgery.

Comparative Evaluation of Retinal Nerve Fiber Layer Thickness After Conventional Brilliant Blue Assisted Internal Limiting Membrane Peeling Versus Brilliant Blue Selective Staining Using Whole Blood in Macular Hole Surgery

BACKGROUND AND OBJECTIVE

To evaluate retinal nerve fiber layer (RNFL) thickness after conventional brilliant blue (BB) assisted macular hole (MH) surgery versus BB selective staining using whole blood (WB) in MH surgery.

PATIENTS AND METHODS

Sixty eyes with stage 4 idiopathic MH with a clear media were randomly divided into two equal groups. Group A eyes underwent sequential intraoperative use of autologous heparinized WB followed by BB dye for staining internal limiting membrane, whereas eyes in group B were subjected to conventional BB staining. Clinical examination and spectral-domain optical coherence tomography was done preoperatively and postoperatively up to 6 months.

RESULTS

Mean global RNFL thickness and mean temporal RNFL thickness decreased in both groups postoperatively, but the reduction in RNFL thickness in group B was greater than group A at all postoperative visits (P < .05).

CONCLUSION

BB toxicity may be responsible for reduction of RNFL thickness and WB appears to protect RNFL against dye toxicity. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:436-442.].

Toluidine Blue 0.05% Vital Staining for the Diagnosis of Ocular Surface Squamous Neoplasia in Kenya

IMPORTANCE

Clinical features are unreliable for distinguishing ocular surface squamous neoplasia (OSSN) from benign conjunctival lesions.

OBJECTIVE

To evaluate the adverse effects, accuracy, and interobserver variation of toluidine blue 0.05% vital staining in distinguishing OSSN, confirmed by histopathology, from other conjunctival lesions.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study in Kenya from July 2012 through July 2014 of 419 adults with suspicious conjunctival lesions. Pregnant and breastfeeding women were excluded.

EXPOSURES

Comprehensive ophthalmic slitlamp examination was conducted. Vital staining with toluidine blue 0.05% aqueous solution was performed before surgery. Initial safety testing was conducted on large tumors scheduled for exenteration looking for corneal toxicity on histology before testing smaller tumors. We asked about pain or discomfort after staining and evaluated the cornea at the slitlamp for epithelial defects. Lesions were photographed before and after staining.

MAIN OUTCOMES AND MEASURES

Diagnosis was confirmed by histopathology. Six examiners assessed photographs from a subset of 100 consecutive participants for staining and made a diagnosis of OSSN vs non-OSSN. Staining was compared with histopathology to estimate sensitivity, specificity, and predictive values. Adverse effects were enumerated. Interobserver agreement was estimated using the κ statistic.

RESULTS

A total of 143 of 419 participants (34%) had OSSN by histopathology. The median age of all participants was 37 years (interquartile range, 32-45 years) and 278 (66%) were female. A total of 322 of the 419 participants had positive staining while 2 of 419 were equivocal. There was no histological evidence of corneal toxicity. Mild discomfort was reported by 88 (21%) and mild superficial punctate keratopathy seen in 7 (1.7%). For detecting OSSN, toluidine blue had a sensitivity of 92% (95% CI, 87%-96%), specificity of 31% (95% CI, 25%-36%), positive predictive value of 41% (95% CI, 35%-46%), and negative predictive value of 88% (95% CI, 80%-94%). Interobserver agreement was substantial for staining (κ = 0.76) and moderate for diagnosis (κ = 0.40).

CONCLUSIONS AND RELEVANCE

With the high sensitivity and low specificity for OSSN compared with histopathology among patients with conjunctival lesions, toluidine blue 0.05% vital staining is a good screening tool. However, it is not a good diagnostic tool owing to a high frequency of false-positives. The high negative predictive value suggests that a negative staining result indicates that OSSN is relatively unlikely.

Preoperative and intraoperative prognostic factors of epiretinal membranes using chromovitrectomy and internal limiting membrane peeling

BACKGROUND AND OBJECTIVE

To evaluate the preoperative and intraoperative findings as prognostic indicators of functional and anatomic results of idiopathic epiretinal membrane (ERM) surgery.

PATIENTS AND METHODS

Vitrectomies included ERM and internal limiting membrane (ILM) removal with vital dyes. Best corrected visual acuity (BCVA), optical coherence tomography (OCT), fluorescein angiography, and autofluorescence were performed at baseline and postoperatively. Intraoperative ILM status after ERM removal was also evaluated.

RESULTS

Thirty-one eyes were monitored for a mean of 16.78 months. BCVA and central foveal thickness (CFT) improved significantly (P < .001) from baseline at 3 and 12 months. Preoperative hyperautofluorescence was associated with greater CFT reduction (P < .005). ILM status after ERM peeling did not influence visual recovery but was associated with anatomical results as measured by OCT.

CONCLUSION

Preoperative poor initial BCVA and RPE defects by FAF may not be bad prognostic factors. Preoperative hyperautofluorescence was associated with greater CFT reduction. Intraoperative classification of ILM status after ERM and ILM staining/peeling was reported and may be useful for future studies, though it was not associated neither with preoperative nor postoperative BCVA.

Luminescence-based Imaging Approaches in the Field of Interventional Molecular Imaging

Luminescence imaging-based guidance technologies are increasingly gaining interest within surgical and radiologic disciplines. Their promise to help visualize molecular features of disease in real time and with microscopic detail is considered desirable. Integrating luminescence imaging with three-dimensional radiologic- and/or nuclear medicine-based preinterventional imaging may overcome limitations such as the limited tissue penetration of luminescence signals. At the same time, the beneficial features of luminescence imaging may be used to complement the routinely used radiologic- and nuclear medicine-based modalities. To fully exploit this integrated concept, and to relate the largely experimental luminesce-based guidance approaches into perspective with routine imaging approaches, it is essential to understand the advantages and limitations of this relatively new modality. By providing an overview of the available luminescence technologies and the various clinically evaluated exogenous luminescent tracers (fluorescent, hybrid, and theranostic tracers), this review attempts to place luminescence-based interventional molecular imaging technologies into perspective to the available radiologic- and/or nuclear medicine-based imaging technologies. At the same time, the transition from anatomic to physiologic and even molecular interventional luminescence imaging is illustrated.

Histological Stains: A Literature Review and Case Study

The history of histology indicates that there have been significant changes in the techniques used for histological staining through chemical, molecular biology assays and immunological techniques, collectively referred to as histochemistry. Early histologists used the readily available chemicals to prepare tissues for microscopic studies; these laboratory chemicals were potassium dichromate, alcohol and the mercuric chloride to harden cellular tissues. Staining techniques used were carmine, silver nitrate, Giemsa, Trichrome Stains, Gram Stain and Hematoxylin among others. The purpose of this research was to assess past and current literature reviews, as well as case studies, with the aim of informing ways in which histological stains have been improved in the modern age. Results from the literature review has indicated that there has been an improvement in histopathology and histotechnology in stains used. There has been a rising need for efficient, accurate and less complex staining procedures. Many stain procedures are still in use today, and many others have been replaced with new immunostaining, molecular, non-culture and other advanced staining techniques. Some staining methods have been abandoned because the chemicals required have been medically proven to be toxic. The case studies indicated that in modern histology a combination of different stain techniques are used to enhance the effectiveness of the staining process. Currently, improved histological stains, have been modified and combined with other stains to improve their effectiveness.

Vitreomacular traction syndrome: postoperative functional and anatomic outcomes

BACKGROUND AND OBJECTIVE

To analyze a variety of vitreomacular traction (VMT) morphologies to establish a major classification that better reflects the preoperative predictive factors of postoperative visual and anatomic outcomes.

PATIENTS AND METHODS

Thirty-six eyes submitted to vitrectomy surgery were categorized with a VMT pattern (V- or J-shaped) and diameter (focal < 1,500 µm or broad > 1,500 µm) based on optical coherence tomography.

RESULTS

The researchers compared different classifications of VMT. Despite similar postoperative best corrected visual acuity (BCVA) values (P = .393), cases with focal VMT had greater visual improvement (P = .027) because the preoperative BCVA was significantly lower in the focal group (P = .007). However, the BCVA improvements did not differ between the groups regarding the classic VMT morphologic patterns (P = .235).

CONCLUSION

Postoperative outcomes and macular disorders are closely related to VMT size. The adhesion diameter (focal or broad VMT) and not the classic VMT morphologic pattern (V- or J-shaped) may better predict the postoperative anatomic and functional outcomes.

Indocyanine green assisted removal of orbital lacrimal duct cysts in children

Aim. To report on the use of indocyanine green (ICG) during surgical removal of pediatric orbital lacrimal duct cysts. Method. We conducted a retrospective review of our cases of surgical excision of orbital lacrimal duct cysts using intraoperative injection of indocyanine green (ICG), which was used following inadvertent cyst rupture and volume loss. The dye allowed complete cyst visualization and complete excision despite volume loss or cyst rupture. Results. The study included 6 children (3 boys, mean age of 4.2 ± 0.84 years, range 3–5 years). Mean follow-up period was 9.3 months. All cysts were located in the inferonasal quadrant of the orbit (4 in the right side). In all cases, ICG was injected into the cyst at the time of surgery following unintentional cyst rupture. After the dye injection, it was easy to identify the borders of the cyst, permitting complete cyst removal, without any intra- or postoperative complications. Pathological examination revealed that all cysts were of lacrimal duct origin. Conclusion. Intraoperative injection of ICG into orbital cysts in children can aid surgeons in identifying cyst borders following inadvertent rupture, allowing complete removal.

Dye solutions based on lutein and zeaxanthin: in vitro and in vivo analysis of ocular toxicity profiles

PURPOSE

To study the safety profile of Lutein/Zeaxanthin(L/Z)-based natural dye solutions in in vitro and in vivo models.

MATERIAL AND METHODS

In vitro cytotoxicity and cellular growth experiments were carried out on ARPE-19 and human corneal epithelial (HCE) cell lines using different L/Z-based dye solutions, either alone or in association with brilliant blue (BB) or trypan blue (TB). Light and transmission electron microscopy studies were performed seven days after intravitreal injection of dye solutions in rabbits. Electroretinogram (ERG) recordings were taken at baseline and before histopathology.

RESULTS

In vitro cytotoxicity assays demonstrated that the different L/Z-based solutions (from 0.3 to 2%), either alone or in association with BB (0.025%) or TB (0.04%), did not significantly alter mitochondrial activity (≤15%) in the cell lines tested. In addition, in vitro cell growth was inhibited by up to 60% depending on the dye solution, and in direct proportion to the concentration assayed. There was no evidence of structural alterations in the neurosensory retina, retinal pigment epithelium (RPE), or choriocapillaris-choroidal complex. b-Wave ERG records showed no significant differences (±15.2%) in comparison with baseline.

CONCLUSIONS

L/Z-based dye solutions demonstrated a safe profile in in vitro and in vivo models, and may be a useful tool for staining intraocular structures.

Lutein: a new dye for chromovitrectomy

PURPOSE

To evaluate the feasibility, advantages, and safety of a novel lutein-based dye for improving identification and removal of the vitreous, internal limiting membrane, and epiretinal membrane during chromovitrectomy in humans.

METHODS

We prospectively evaluated 12 eyes that underwent pars plana vitrectomy using the dye in patients with macular hole, epiretinal membrane, or proliferative diabetic retinopathy/tractional diabetic macular edema. One surgeon performed standard chromovitrectomy and completed a postoperative questionnaire to compare the staining with that of the available dyes. The peeled membranes were evaluated histologically. Follow-up examinations were performed on postoperative Days 1, 7, 30, 90 and 180; best-corrected visual acuity, optical coherence tomography, fluorescein angiography, autofluorescence, and visual fields were performed.

RESULTS

The green dye was deposited on the posterior pole because of its higher density than balanced saline solution; vigorous dye flushing into the vitreous cavity was unnecessary. The dye stained the posterior hyaloid/vitreous base by deposition onto the vitreous; brilliant blue stained the internal limiting membrane. The epiretinal membrane was poorly stained. The best-corrected visual acuity improved in all eyes without clinical toxicity or toxicity on images/visual fields. Histology showed effective removal of the internal limiting membrane and epiretinal membrane in all eyes.

CONCLUSION

The new dye improved intraoperative identification of the internal limiting membrane and the posterior hyaloid/vitreous base during chromovitrectomy.

Gingiva laser welding: preliminary study on an ex vivo porcine model

OBJECTIVE

The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding.

MATERIALS AND METHODS

Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera.

RESULTS

In the laser welding groups, the best tensile strength (p<0.05) was yielded by the 9% ICG saline solution (117 mM) at 4.5 W, 10 Hz, and a fluence of 31.3 kJ/cm(2). The apposition strength revealed no statistically significant difference (p<0.05) between the sutured and the laser welded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 μm at the upper surface.

CONCLUSIONS

The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.

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.

Storage and qualification of viable intact human amniotic graft and technology transfer to a tissue bank

Human amniotic membrane (hAM) is known to have good potential to help the regeneration of tissue. It has been used for over 100 years in many medical disciplines because of its properties, namely a scaffold containing stem cells and growth factors, with low immunogenicity and anti-microbial, anti-inflammatory, anti-fibrotic and analgesic properties. In order to use this "boosted membrane" as an advanced therapeutic medicinal product for bone repair, we aimed to observe the influence of tissue culture and/or cryopreservation on cell viability and tissue structure, and secondly, to adapt to a tissue bank, identify easy processes to store hAM containing viable cells and to verify the quality of the graft before its release for use. To this end, we tested different published culture or cryopreservation storage conditions and cell viability assays. Tissue structure was evaluated by Giemsa staining and was compared to histological analysis. Preliminary results show no dramatic decrease in cell viability in cultured hAM as compared to cryopreserved hAM, but tissue structure alterations were observed with both storage conditions. Histological and immunohistochemical data highlight that tissue damage was associated with significantly modified protein expression, which could lead to a possible loss of differentiation potential. Finally, we report that trypan blue and Giemsa staining could constitute controls that are "materially and easily transferable" to a tissue bank.

The Expansion of RPE Atrophy after the Inverted ILM Flap Technique for a Chronic Large Macular Hole

Purpose

To report a case of the expansion of submacular retinal pigment epithelium (RPE) atrophy after using the inverted internal limiting membrane (ILM) flap technique for a persisting, large, stage IV macular hole (MH).

Case Report

A 79-year-old woman presented with a chronic large MH that remained open despite pars plana vitrectomy (PPV). The surgery was performed twice for the MH closure 14 years earlier. ILM peeling was not performed during the previous surgeries. The best-corrected visual acuity (BCVA) with the Landolt ring chart was 0.08 at her visit. The minimum MH diameter was 1,240 μm. Inverted ILM flap technique with 20% SF6 gas tamponade was performed for the MH closure. For the inverted ILM flap technique, 25-gauge PPV and ILM staining with indocyanine green were used. The ILM was peeled off for 2 disc diameters around the MH, but the ILM was not removed completely. The ILM was then inverted and covered the MH.

Results

One month after surgery, the MH was closed, accompanied by glial cell proliferation spreading from the inverted ILM flap (as reported before). On the other hand, the area of the submacular RPE atrophy, which was already observed 1 week after surgery, gradually increased in size. BCVA improved to 0.3 six months after the surgery.

Conclusions

The inverted ILM flap technique may be promising even for persisting large MH which were not closed in previous surgeries, but long-term observation is needed because the detailed behavior of the inverted ILM and the Müller cells after surgery is not yet known.

Indocyanine green concentrations used in chromovitrectomy cause a reversible functional alteration in the outer blood-retinal barrier

PURPOSE

To assess tight junction integrity in cultured human foetal retinal pigment epithelium (RPE) after exposure to clinically relevant indocyanine green (ICG) concentrations.

METHODS

Human foetal RPE was cultured with the Hu & Bok method. The apical compartments of well-differentiated cultures were exposed to 0.125, 0.05 and 0.025 mg/ml ICG with or without 10-min illumination. Vehicle and trypsin/EDTA or EDTA alone served as controls. Three minutes was chosen to mimic surgical exposure time, while 3 h was used for toxicity assays, with subsequent wash out. Cell-cell junctions were studied before and after exposure by phase contrast microscopy and immunofluorescence (ZO-1). Blood-retinal barrier function was measured through transepithelial electrical resistance (TER).

RESULTS

At 6-8 weeks postconfluence, RPE had grown into pigmented hexagonal monolayers with stable TER (435-1227 Ω*cm(2) ). After 3 min ICG exposure, cell morphology remained unchanged, with patchy cell-cell dissociation in positive controls. A continuous ZO-1 signal was detected in ICG groups, whereas trypsin controls showed patchy loss of the tight junction stain. TER had dropped at 1.5 h after 3 min exposure to 22.8 ± 3.1%, compared with 10.2 ± 3.9% in positive controls. Surgical light illumination did not affect TER. After 3 h exposure to 0.05 mg/ml ICG, TER decreased to 58.1 ± 8.3%, while vehicle controls maintained similar levels as prior to exposure (92.7 ± 2.4%). TER recovered in all ICG groups to prior levels within 3 days.

CONCLUSION

Indocyanine green (ICG) exposure induced a transient decrease in transepithelial electrical resistance, despite unaltered tight junction structure.