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

PRETREATED LYOPHILIZED HUMAN AMNIOTIC MEMBRANE GRAFT COVERING FOR RETINAL DETACHMENT WITH POSTERIOR RETINAL BREAKS ABOVE CHORIORETINAL ATROPHY IN PATHOLOGIC MYOPIA

PURPOSE

To compare the surgical results of vitrectomy with untreated or pretreated lyophilized human amniotic membrane grafts covering in treating retinal detachment related to posterior retinal breaks above chorioretinal atrophy in pathologic myopia.

METHODS

Nineteen patients with retinal detachment related to macular hole (MH) located above macular atrophy and/or posterior paravascular retinal breaks (PRBs) located above patchy chorioretinal atrophy in pathologic myopia were included. The eyes of these patients underwent vitrectomy with untreated lyophilized human amniotic membrane covering (n = 10) or perfluorocarbon liquid (PFCL)-assisted pretreated lyophilized human amniotic membrane covering (n = 9; grafts were pretreated in 0.125% indocyanine green and 50% hypertonic glucose solution for 15-20 minutes). The closure of the MH or PRBs, reattachment of the retina, and best-corrected visual acuity were measured postoperatively.

RESULTS

Postoperatively, graft dislocation or shift was only found in two eyes (20%) in the untreated group. The closure rate of the MH or PRBs was 80% (8/10) and 100% (9/9) in the untreated group and the pretreated group, respectively. The occurrence rate of excessive gliosis was 40% and 11% in the untreated group and the pretreated group, respectively. In both groups, best-corrected visual acuity was improved and the retinal reattachment rate was 100% at the final visit.

CONCLUSION

Perfluorocarbon liquid-assisted pretreated lyophilized human amniotic membrane graft covering was effective in treating retinal detachment related to MH and/or PRBs situated above macular atrophy or patchy chorioretinal atrophy in pathologic myopia. This technique appeared to reduce graft dislocation or shift, promote the closures of MHs/PRBs, and reduce the occurrence of gliosis.

Recent Advancements and Strategies for Overcoming the Blood-Brain Barrier Using Albumin-Based Drug Delivery Systems to Treat Brain Cancer, with a Focus on Glioblastoma

Glioblastoma multiforme (GBM) is a highly aggressive malignant tumor, and the most prevalent primary malignant tumor affecting the brain and central nervous system. Recent research indicates that the genetic profile of GBM makes it resistant to drugs and radiation. However, the main obstacle in treating GBM is transporting drugs through the blood-brain barrier (BBB). Albumin is a versatile biomaterial for the synthesis of nanoparticles. The efficiency of albumin-based delivery systems is determined by their ability to improve tumor targeting and accumulation. In this review, we will discuss the prevalence of human glioblastoma and the currently adopted treatment, as well as the structure and some essential functions of the BBB, to transport drugs through this barrier. We will also mention some aspects related to the blood-tumor brain barrier (BTBB) that lead to poor treatment efficacy. The properties and structure of serum albumin were highlighted, such as its role in targeting brain tumors, as well as the progress made until now regarding the techniques for obtaining albumin nanoparticles and their functionalization, in order to overcome the BBB and treat cancer, especially human glioblastoma. The albumin drug delivery nanosystems mentioned in this paper have improved properties and can overcome the BBB to target brain tumors.

Translational screening platform to evaluate chemotherapy in combination with focal therapy for retinoblastoma

Retinoblastoma is the most common pediatric eye cancer. It is currently treated with a limited number of drugs, adapted from other pediatric cancer treatments. Drug toxicity and relapse of the disease warrant new therapeutic strategies for these young patients. In this study, we developed a robust tumoroid-based platform to test chemotherapeutic agents in combination with focal therapy (thermotherapy) - a treatment option widely used in clinical practice - in accordance with clinically relevant trial protocols. The model consists of matrix-embedded tumoroids that retain retinoblastoma features and respond to repeated chemotherapeutic drug exposure similarly to advanced clinical cases. Moreover, the screening platform includes a diode laser (810 nm, 0.3 W) to selectively heat the tumoroids, combined with an on-line system to monitor the intratumoral and surrounding temperatures. This allows the reproduction of the clinical settings of thermotherapy and combined chemothermotherapy treatments. When testing the two main drugs currently used in clinics to treat retinoblastoma in our model, we observed results similar to those clinically obtained, validating the utility of the model. This screening platform is the first system to accurately reproduce clinically relevant treatment methods and should lead to the identification of more efficient drugs to treat retinoblastoma.

Implant-Based Breast Reconstruction after Risk-Reducing Mastectomy in BRCA Mutation Carriers: A Single-Center Retrospective Study

Women with BRCA gene mutations have a higher lifetime risk of developing breast cancer. Furthermore, cancer is usually diagnosed at a younger age compared to the wild-type counterpart. Strategies for risk management include intensive surveillance or risk-reducing mastectomy. The latter provides a significant reduction of the risk of developing breast cancer, simultaneously ensuring a natural breast appearance due to the preservation of the skin envelope and the nipple-areola complex. Implant-based breast reconstruction is the most common technique after risk-reducing surgery and can be achieved with either a submuscular or a prepectoral approach, in one or multiple stages. This study analyzes the outcomes of the different reconstructive techniques through a retrospective review on 46 breasts of a consecutive, single-center case series. Data analysis was carried out with EpiInfo version 7.2. Results of this study show no significant differences in postoperative complications between two-stage tissue expander/implant reconstruction and direct-to-implant (DTI) reconstruction, with DTI having superior aesthetic outcomes, especially in the prepectoral subgroup. In our experience, the DTI prepectoral approach has proven to be a safe and less time-consuming alternative to the submuscular two-stage technique, providing a pleasant reconstructed breast and overcoming the drawbacks of subpectoral implant placement.

Indocyanine Green Aided Schlemm Canal Identification During Gonioscopic Assisted Transluminal Trabeculotomy

Performing procedures like gonioscopic assisted transluminal trabeculotomy in eyes with congenital glaucoma may be difficult many a times due to difficult visualization of angle structures. Inaccurate identification of the angle landmark may lead to various inadvertent surgical complications. Hence, there is a need for techniques to improve visualization of surgical landmarks during these procedures. In this study, 0.2% indocyanine green was used to stain the trabecular meshwork before the surgeon proceeded with gonioscopic assisted transluminal trabeculotomy. It yielded excellent differentiation of the trabecular meshwork by imparting a bright green hue. This led to successful identification of the site of incision and subsequent 360 degrees cannulation of Schlemm canal in 5/5 cases. Indocyanine green aided Schlemm canal identification is helpful in children with congenital glaucoma undergoing angle surgeries, especially in eyes with poor structure differentiation.

ICG-mediated photodisruption of the inner limiting membrane enhances retinal drug delivery

Many groundbreaking therapies for the treatment of blindness require delivery of biologics or cells to the inner retina by intravitreal injection. Unfortunately, the advancement of these therapies is greatly hampered by delivery difficulties where obstruction of the therapeutics at the inner limiting membrane (ILM) represents the dominant bottleneck. In this proof-of-principle study, we explore an innovative light-based approach to locally ablate the ILM in a minimally invasive and highly controlled manner, thus making the ILM more permeable for therapeutics. More specifically, we demonstrate that pulsed laser irradiation of ILM-bound indocyanine green (ICG), a clinically applied ILM dye, results in the formation of vapor nanobubbles which can disrupt the bovine ILM as well as the extraordinary thick human ILM. We have observed that this photodisruption allows for highly successful retinal delivery of model nanoparticles which are otherwise blocked by the intact ILM. Strikingly, this treatment is furthermore able of enhancing the efficacy of mRNA-loaded lipid nanoparticles within the bovine retina by a factor of 5. In conclusion, this study provides evidence for a light-based approach to overcome the ILM which has the potential to improve the efficacy of all retinal therapies hampered by this delivery barrier.

Internal limiting membrane peeling in macular hole surgery

Since the era when macular hole was considered untreatable, macular hole surgery has come a long way to being one of the most successful surgeries. Internal limiting membrane (ILM) peeling has been an essential step of macular hole surgery since the establishment of the role of ILM in the aetiopathogenesis and progression of macular hole. However, the novel technique was not all virtuous. It had some vices which were not evident immediately. With the advent of spectral domain optical coherence tomography, short- and long-term effects of ILM peeling on macular structures were known; and with microperimetry, its effect on the function of macula could be evaluated. The technique has evolved with time from total peeling to inverted flap to just temporal peeling and temporal flap in an attempt to mitigate its adverse effects and to improve its surgical outcome. ILM abrasion technique and Ocriplasmin may eliminate the need of ILM peeling in selected cases, but they have their own limitations. We here discuss the role of ILM in the pathogenesis of macular hole, the benefits and adverse effects of ILM peeling, and the various modifications of the procedure, to then explore the alternatives.

Analysis of Factors Affecting 5-ALA Fluorescence Intensity in Visualizing Glial Tumor Cells-Literature Review

Glial tumors are one of the most common lesions of the central nervous system. Despite the implementation of appropriate treatment, the prognosis is not successful. As shown in the literature, maximal tumor resection is a key element in improving therapeutic outcome. One of the methods to achieve it is the use of fluorescent intraoperative navigation with 5-aminolevulinic acid. Unfortunately, often the level of fluorescence emitted is not satisfactory, resulting in difficulties in the course of surgery. This article summarizes currently available knowledge regarding differences in the level of emitted fluorescence. It may depend on both the histological type and the genetic profile of the tumor, which is reflected in the activity and expression of enzymes involved in the intracellular metabolism of fluorescent dyes, such as PBGD, FECH, UROS, and ALAS. The transport of 5-aminolevulinic acid and its metabolites across the blood–brain barrier and cell membranes mediated by transporters, such as ABCB6 and ABCG2, is also important. Accompanying therapies, such as antiepileptic drugs or steroids, also have an impact on light emission by tumor cells. Accurate determination of the factors influencing the fluorescence of 5-aminolevulinic acid-treated cells may contribute to the improvement of fluorescence navigation in patients with highly malignant gliomas.

Indocyanine Green Fluorescence-Guided Sentinel Node Biopsy in Breast Cancer Within a North African Population: A Retrospective Study

Objective

Radio isotopes and blue dyes alone or in combination are the most commonly used tracer agents in sentinel node (SN) biopsy for early breast cancer. Recent studies have found fluorescence method using indocyanine green (ICG) as a promising technology with fewer disadvantages.

Materials and Methods

Retrospective analysis of our database that included patients with clinically node-negative breast cancer scheduled for breast surgery and SN biopsy between 2016 and January 2021. Patients who underwent detection using fluorescence-ICG were included in this study.

Results

A total of 47 patients were included. Median age was 50 (range: 24-78) years. Mean tumor size was 3.4 ± 1.5 cm. All patients received ICG injection and 11 received a combination of ICG and blue dye. Forty-five successful SN identifications with ICG were performed and 99 nodes retrieved. Eleven procedures were undertaken after initial systemic therapy. Twenty-four patients had at least one positive SN for malignancy. Mean follow up was 29.2 months and no axillary recurrence was noted during the study period.

Conclusion

ICG appears to be a feasible and accurate method for SN biopsy with high identification rate. This is the first study of ICG in sentinel node biopsy in a North African population.

OUTER RETINAL INJURY SECONDARY TO MEMBRANE PEELING WITH INTERNAL LIMITING MEMBRANE FORCEPS

PURPOSE

To present a case of visually significant retinal injury due to internal limiting membrane (ILM) peeling using ILM forceps alone.

METHODS

Case report.

RESULTS

A 60-year-old woman who underwent ILM peeling for an epiretinal membrane presented with linear central scotomata. Peeling had been initiated and performed with ILM forceps alone, without the use of other surgical instruments. Fundus examination and spectral domain optical coherence tomography imaging confirmed the presence of several discrete areas of inner and outer retinal injury in the macula, which corresponded to her scotomata.

CONCLUSION

This is a case of visually significant retinal injury due to ILM peeling that was performed with ILM forceps alone. Improper peeling technique can transmit injurious forces to the retina. Surgeons must be mindful of the biomechanical forces involved in ILM peeling to minimize traction on the retina.

Long-Term Outcomes of Macular Hole Repair with Triamcinolone Acetonide Visualization

Purpose

To evaluate the long-term anatomic and visual outcomes of macular hole (MH) repair utilizing triamcinolone acetonide (TA) visualization of the internal limiting membrane (ILM) treated at a tertiary care retina practice.

Methods

Retrospective chart review of eyes undergoing MH repair with ILM peel utilizing TA visualization followed by gas tamponade and facedown positioning between 2014 and 2020. Pre- and post-operative visual acuity (VA), IOP, and anatomic closure based on optical coherence tomography were documented.

Results

Seventy-eight eyes were followed for 2.3±0.2 years after primary repair with anatomic closure in 73 (94%) eyes at their final visit and excluding eyes with pathologic myopia, 97%, and for stage 2 and small MHs, 100%. In all eyes, VA significantly improved from 0.97±0.04 (Snellen: 20/187) to 0.66±0.06 (20/91) logMAR (p < 0.0001). There were 16 eyes with 4 years of follow-up, 10 (63%) eyes achieving a VA ≥20/30 at that follow-up visit. Stage 2 and 3 MHs had significantly greater improvements in VA than Stage 4 MHs, −0.46 ± 0.06 versus −0.11 ± 0.11 logMAR (p = 0.021). Of the 13 (17%) eyes with recurrent MHs, 6 (46%) had pathologic myopia and 8 (61.5%) had associated cystoid macular edema. Cataract progression was reported in 52 (96%) phakic eyes and 2 eyes required Ahmed valve placement for management of pre-existing glaucoma.

Conclusion

Long-term results of MH repair with TA for ILM visualization demonstrate that it is safe and effective. Visual acuity continued to improve throughout the follow-up. Pre-existing glaucoma may progress and recurrence is associated with pathologic myopia and macular edema.

Characteristics of Fluorescent Intraoperative Dyes Helpful in Gross Total Resection of High-Grade Gliomas-A Systematic Review

Background: A very important aspect in the treatment of high-grade glioma is gross total resection to reduce the risk of tumor recurrence. One of the methods to facilitate this task is intraoperative fluorescence navigation. The aim of the study was to compare the dyes used in this technique fluorescent intraoperative navigation in terms of the mechanism of action and influence on the treatment of patients. Methods: The review was carried out on the basis of articles found in PubMed, Google Scholar, and BMC search engines, as well as those identified by searched bibliographies and suggested by experts during the preparation of the article. The database analysis was performed for the following phrases: "glioma", "glioblastoma", "ALA", "5ALA", "5-ALA", "aminolevulinic acid", "levulinic acid", "fluorescein", "ICG", "indocyanine green", and "fluorescence navigation". Results: After analyzing 913 citations identified on the basis of the search criteria, we included 36 studies in the review. On the basis of the analyzed articles, we found that 5-aminolevulinic acid and fluorescein are highly effective in improving the percentage of gross total resection achieved in high-grade glioma surgery. At the same time, the limitations resulting from the use of these methods are marked-higher costs of the procedure and the need to have neurosurgical microscope in combination with a special light filter in the case of 5-aminolevulinic acid (5-ALA), and low specificity for neoplastic cells and the dependence on the degree of damage to the blood-brain barrier in the intensity of fluorescence in the case of fluorescein. The use of indocyanine green in the visualization of glioma cells is relatively unknown, but some researchers have suggested its utility and the benefits of using it simultaneously with other dyes. Conclusion: The use of intraoperative fluorescence navigation with the use of 5-aminolevulinic acid and fluorescein allows the range of high-grade glioma resection to be increased.

Ultrafast, Ultrasensitive Detection and Imaging of Single Cardiac Troponin-T Molecules

The fluorescence-based methods of single-molecule optical detection have opened up unprecedented possibilities for imaging, monitoring, and sensing at a single-molecule level. However, single-molecule detection methods are very slow, making them practically inapplicable. In this paper, we show how to overcome this key limitation using the expanded laser spot, laser excitation in a nonfluorescent spectral window of biomolecules, and more binding fluorescent molecules on a biomolecule that increases the detection volume and the number of collected photons. We demonstrate advantages of the developed approach unreachable by any other technique using detection of single cardiac troponin-T molecules: (i) 1000-fold faster than by known approaches, (ii) real-time imaging of single troponin-T molecules dissolved in human blood serum, (iii) measurement of troponin-T concentration with a clinically important sensitivity of about 1 pg/mL. The developed approach can be used for ultrafast, ultrasensitive detection, monitoring, and real-time imaging of other biomolecules as well as of larger objects including pathogenic viruses and bacteria.

Pre-operative predicting factor in visual outcome after macular hole surgery

Objective:

To determine the effectiveness of macular hole index (MHI) as a predicting factor of visual outcome after full thickness macular hole surgery.

Methods:

This quasi-experimental study was conducted at LRBT Free Base Eye Hospital, Karachi from January 2018 to March 2019. Total 45 eyes of 45 patients with full thickness macular hole (FTMH) underwent preoperative Best Corrected Visual Acuity (BCVA) assessment with logMar chart and Optical Coherence Tomography (OCT) scanning, with measurement of base diameter and macular hole height. Values were calculated for the macular hole index (MHI), which was taken as the predictive factor. All patients had undergone 25⁺G trans-conjunctival three ports pars plana vitrectomy, internal limiting membrane peeling, and endo-tamponade of C₃F₈(14%). The final visual outcome of all the patients was noted.

Results:

Forty-five patients were included for the study, out of which 10 (22.2%) were male and 35 (77.7%) were female. Age ranged from 45-70 years (mean age 57.20±6.47 years). The mean pre-operative visual acuity was 2.46±1.15 logMar and was 3.88±2.00 logMar, post-operatively. Moreover, 27(60.0%) out of 45 patients achieved BCVA (gain of 2 lines of the logMar chart). The average macular hole index was 1.55±0.50 and out of 45, 25 patients had MHI ≥0.5. It was found that patients with macular hole index ≥0.50 showed clinically significant improvement in BCVA in comparison to those who have macular hole index <0.50.

Conclusion:

Macular hole index can be used to predict functional success in macular hole surgery.

Near-Infrared-Guided Pulmonary Segmentectomy After Endobronchial Indocyanine Green Injection

BACKGROUND

The aim of this study is to prospectively determine the feasibility and safety of near-infrared fluorescence-guided pulmonary segmentectomy after endobronchial indocyanine green (ICG) injection using virtual bronchoscopy.

METHODS

Fifteen patients who underwent pulmonary segmentectomy were prospectively enrolled. Using preoperative computed tomography datasets a bronchial road map was created to determine the bronchus for ICG injection. Immediately after intubation ICG was injected into the target bronchi using an ultrathin bronchoscope. During the operation a near-infrared thoracoscope was used to detect ICG fluorescence and determine the intersegmental plane. The assessment points were (1) whether the ICG demarcation lines corresponded to the intersegmental lines expected from the pulmonary veins, (2) whether it was possible for the planned segmentectomy to be completed by electrocautery and 1 or fewer uses of an automated suturing device according to the demarcation plane, (3) whether any surgical complications occurred intraoperatively or (4) in the 1 month after surgery, and (5) whether the target lesion was removed completely with sufficient surgical margin to evaluate the feasibility and safety of this procedure.

RESULTS

In 13 cases (87%) a segmentectomy was completed in the planned way with sufficient surgical margins. The failure in 2 cases was due to a technical issue in the bronchial injection. No complications developed intraoperatively. Recurrent air leakage occurred in 1 case. No procedure-related adverse event was noted postoperatively.

CONCLUSIONS

Near-infrared-guided pulmonary segmentectomy with endobronchial ICG injection using virtual bronchoscopy was safe and feasible, and minor technical revision can make this procedure more reliable.

Comparison of Individual Retinal Layer Thicknesses after Epiretinal Membrane Surgery with or without Internal Limiting Membrane Peeling

Purpose

To compare changes in the retinal layer thickness and visual outcomes in patients undergoing epiretinal membrane (ERM) surgery with or without internal limiting membrane (ILM) peeling.

Methods

Seventy-six eyes of 76 patients who underwent ERM surgery from January 2013 to March 2015 at the Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea, were analyzed. While ERM removal with ILM peeling was performed in ILM peeling (P) group (n=39), ILM peeling was not performed in non-ILM peeling (NP) group (n=37). Retinal layer segmentation was performed using optical coherence tomography images. Individual retinal layer thicknesses before and at 6 months after ERM surgery were compared. The postoperative best-corrected visual acuity (BCVA) was also compared.

Results

In the P group, the thicknesses of retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) were significantly reduced. In the NP group, significant decreases in the RNFL, GCL, IPL, inner nuclear layer, and outer plexiform layer were observed. The P group manifested a greater mean postoperative GCL (35.56 ± 1.53 µm vs 29.86 ± 2.16 µm; p=0.033) and less loss of GCL (−10.26 ± 1.91 µm vs −19.86 ± 2.74 µm; p=0.004) compared to the NP group. No statistically significant differences were observed when comparing the changes in BCVA.

Conclusions

This study demonstrates that ILM peeling for ERM surgery may result in better preservation of GCL compared to no ILM peeling.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Visual and anatomical outcome of macular hole surgery at a tertiary healthcare facility

Objective:

To assess visual and anatomical outcome of full thickness macular hole (FTMH) surgery with ILM peeling using brilliant blue G dye.

Methods:

Thirty patients who had clinically evident macular hole were selected. Pre-operative Optical Coherence Tomography (OCT) was done. In all cases vitrectomy was performed via 23guage 3 ports pars plana (3PPV) vitrectomy system and Brilliant blue G dye, 0.5ml dye was injected over macula which resulted in light blue stain of ILM and peeling was performed around hole in circular motion and after gas fluid exchange gas tamponade with SF6 was done. Final visual and anatomical outcome was measured as postoperative BCVA and postoperative OCT at three months respectively. Descriptive statistics were computed. Paired t-test was applied. P value≤0.05 were considered as significant.

Results:

There were 12 male and 18 female patients. The mean age was 57.40±4.76 years. The mean size of macular hole was 452.20±242.33μm. The mean duration of symptoms was 16.73±13.49 weeks. Mean pre operative BCVA was 1.30±0.73 log MAR and post operative was 0.51±0.23 log MAR. Mean increased BCVA was found to be 0.22±0.13 log MAR. Primary closure of hole was achieved in 29(96.7%). Significant mean difference was found in pre operative and post operative BCVA.

Conclusion:

Brilliant blue G exhibits sufficient staining qualities and safety profile to peel ILM in the management of full thickness macular hole with significant visual and anatomical improvement.

PARS PLANA VITRECTOMY FOR DIABETIC MACULAR EDEMA: A Systematic Review, Meta-Analysis, and Synthesis of Safety Literature

PURPOSE

To assess the risk and benefit of pars plana vitrectomy for diabetic macular edema.

METHODS

The authors conducted a systematic literature review using PubMed, EMBASE, Web of Science, and Cochrane Central Database of Controlled Trials until September 2014. The population was patients with diabetic macular edema, intervention vitrectomy, comparator macular laser or observation, and efficacy outcome visual acuity and central retinal thickness. Safety outcomes were intraoperative and postoperative surgical complications. The efficacy meta-analysis included only randomized controlled trials. The safety analysis included prospective, retrospective, controlled, and uncontrolled studies.

RESULTS

Five studies were eligible for the efficacy meta-analysis (n = 127 eyes) and 40 for the safety analysis (n = 1,562 eyes). Combining follow-up intervals from 6 to 12 months, the meta-analysis found a nonsignificant 2 letter visual acuity difference favoring vitrectomy, and a significant 102 μm greater reduction in central retinal thickness favoring vitrectomy, but a post hoc subgroup analysis found that a 6-month central retinal thickness benefit reversed by 12 months. The most frequent complications were retinal break (7.1%), elevated intraocular pressure (5.2%), epiretinal membrane (3.3%), and vitreous hemorrhage (2.4%). Cataract developed in 68.6% of 121 phakic eyes.

CONCLUSION

Vitrectomy produces structural and functional improvements in select eyes with diabetic macular edema, but the visual gains are not significantly better than with laser or observation. No major safety concerns were identified.

Macular hole surgery: an analysis of risk factors for the anatomical and functional outcomes with a special emphasis on the experience of the surgeon

Purpose

The aim of this study was to evaluate risk factors for the anatomical and functional outcomes of macular hole (MH) surgery with special emphasis on the experience of the surgeon.

Methods

A total of 225 surgeries on idiopathic MHs (IMHs) performed by 6 surgeons with a mean follow-up period of 20.5 months were reviewed in this retrospective study. Outcome parameters focused on IMH closure, complications and visual acuity improvement. The results of MH surgeries performed by experienced surgeons were compared to those of surgeons in training.

Results

The average MH size was 381 µm (standard deviation [SD]=168). Brilliant blue G (BBG) for internal limiting membrane (ILM) staining was used in 109 (48%) eyes and indocyanine green (ICG) in 116 (52%) eyes. As endotamponade, 20% SF6 was used in 38 (17%) cases, 16% C2F6 in 33 (15%) cases and 16% C3F8 in 154 (68%) cases. IMH closure was achieved in 194 eyes (86%). Mean preoperative visual acuity was 0.84 logarithm of the minimum angle of resolution (log MAR; SD=0.29, range: 0.3–1.5); surgery led to a mean improvement of 0.40 (SD=0.37) log MAR. Although the MH closure rate was the same using BBG or ICG for ILM peeling, visual acuity improvement was better in eyes peeled with BBG compared to eyes peeled with ICG (log MAR: BBG: 0.38 [95% CI: 0.32, 0.44] vs ICG: 0.48 [95% CI: 0.42, 0.54], P=0.029). Surgeons with previous experience in vitreoretinal surgery of ≥6 years achieved better visual outcomes compared to surgeons with 0–3 years of experience, regardless of the MH size, preoperative visual acuity, time to follow-up or dye used for ILM peeling (0–3 years [0.27, Δlog MAR] vs ≥6 years [0.43, Δlog MAR], P=0.009).

Conclusion

Our results indicate that vitrectomy with ILM peeling performed by non-experienced surgeons is a safe procedure leading to good anatomical and functional results. Very experienced surgeons may achieve even better functional outcomes.

Noninvasive Assessment of Elimination and Retention using CT-FMT and Kinetic Whole-body Modeling

Fluorescence-mediated tomography (FMT) is a quantitative three-dimensional imaging technique for preclinical research applications. The combination with micro-computed tomography (µCT) enables improved reconstruction and analysis. The aim of this study is to assess the potential of µCT-FMT and kinetic modeling to determine elimination and retention of typical model drugs and drug delivery systems.

We selected four fluorescent probes with different but well-known biodistribution and elimination routes: Indocyanine green (ICG), hydroxyapatite-binding OsteoSense (OS), biodegradable nanogels (NG) and microbubbles (MB). µCT-FMT scans were performed in twenty BALB/c nude mice (5 per group) at 0.25, 2, 4, 8, 24, 48 and 72 h after intravenous injection. Longitudinal organ curves were determined using interactive organ segmentation software and a pharmacokinetic whole-body model was implemented and applied to compute physiological parameters describing elimination and retention.

ICG demonstrated high initial hepatic uptake which decreased rapidly while intestinal accumulation appeared for around 8 hours which is in line with the known direct uptake by hepatocytes followed by hepatobiliary elimination. Complete clearance from the body was observed at 48 h. NG showed similar but slower hepatobiliary elimination because these nanoparticles require degradation before elimination can take place. OS was strongly located in the bones in addition to high signal in the bladder at 0.25 h indicating fast renal excretion. MB showed longest retention in liver and spleen and low signal in the kidneys likely caused by renal elimination or retention of fragments. Furthermore, probe retention was found in liver (MB, NG and OS), spleen (MB) and kidneys (MB and NG) at 72 h which was confirmed by ex vivo data. The kinetic model enabled robust extraction of physiological parameters from the organ curves.

In summary, µCT-FMT and kinetic modeling enable differentiation of hepatobiliary and renal elimination routes and allow for the noninvasive assessment of retention sites in relevant organs including liver, kidney, bone and spleen.

Vision 20/20: Molecular-guided surgical oncology based upon tumor metabolism or immunologic phenotype: Technological pathways for point of care imaging and intervention

Surgical guidance with fluorescence has been demonstrated in individual clinical trials for decades, but the scientific and commercial conditions exist today for a dramatic increase in clinical value. In the past decade, increased use of indocyanine green based visualization of vascular flow, biliary function, and tissue perfusion has spawned a robust growth in commercial systems that have near-infrared emission imaging and video display capabilities. This recent history combined with major preclinical innovations in fluorescent-labeled molecular probes, has the potential for a shift in surgical practice toward resection guidance based upon molecular information in addition to conventional visual and palpable cues. Most surgical subspecialties already have treatment management decisions partially based upon the immunohistochemical phenotype of the cancer, as assessed from molecular pathology of the biopsy tissue. This phenotyping can inform the surgical resection process by spatial mapping of these features. Further integration of the diagnostic and therapeutic value of tumor metabolism sensing molecules or immune binding agents directly into the surgical process can help this field mature. Maximal value to the patient would come from identifying the spatial patterns of molecular expression in vivo that are well known to exist. However, as each molecular agent is advanced into trials, the performance of the imaging system can have a critical impact on the success. For example, use of pre-existing commercial imaging systems are not well suited to image receptor targeted fluorophores because of the lower concentrations expected, requiring orders of magnitude more sensitivity. Additionally the imaging system needs the appropriate dynamic range and image processing features to view molecular probes or therapeutics that may have nonspecific uptake or pharmacokinetic issues which lead to limitations in contrast. Imaging systems need to be chosen based upon objective performance criteria, and issues around calibration, validation, and interpretation need to be established before a clinical trial starts. Finally, as early phase trials become more established, the costs associated with failures can be crippling to the field, and so judicious use of phase 0 trials with microdose levels of agents is one viable paradigm to help the field advance, but this places high sensitivity requirements on the imaging systems used. Molecular-guided surgery has truly transformative potential, and several key challenges are outlined here with the goal of seeing efficient advancement with ideal choices. The focus of this vision 20/20 paper is on the technological aspects that are needed to be paired with these agents.

THE ROYAL COLLEGE OF OPHTHALMOLOGISTS' NATIONAL OPHTHALMOLOGY DATABASE STUDY OF VITREORETINAL SURGERY: Report 4, Epiretinal Membrane

PURPOSE

To report pragmatic outcomes from a database study of epiretinal membrane surgery.

METHODS

Prospective anonymized clinical audit data from electronic medical records were pooled over 10 years into a national database, from 1,131 primary epiretinal membrane operations, by 69 surgeons, in 16 U.K. vitreoretinal units.

RESULTS

The median age of 1,131 patients was 71.6 years. A pars plana vitrectomy and epiretinal membrane peel were combined with internal limiting membrane peel in 17.0% of operations, and cataract surgery in 49.9%. Use of general anesthesia declined from 94.1% in 2001 to 28.9% in 2010. One or more intraoperative complication occurred in 9.8% (8.1% excluding cataract surgery complications). The median preoperative logarithm of the minimum angle of resolution (logMAR) visual acuity improved from 0.60 to 0.30 (Snellen 20/80-20/40) after a median follow-up of 7.0 months; 41.7% of eyes improved ≥0.30 logMAR units (approximately 2 Snellen's lines). The percentages of eyes undergoing subsequent surgery were 3.3%, 1.0%, 0.4%, and 0.8% for epiretinal membrane, retinal detachment, macular hole, and other vitreoretinal indications, respectively. Excluding pseudophakic eyes, 51.7%, 73.2%, and 76.2% of eyes underwent cataract surgery within 1 year, 2 year, and 3 years respectively.

CONCLUSION

These results may help vitreoretinal surgeons to benchmark their surgical outcomes, and patients to assess the risks and benefits of surgery.

Effect of internal limiting membrane abrasion on retinal tissues in macular holes

PURPOSE

The purpose of this study was to identify the structural and histological effects of a Tano diamond-dusted membrane scraper (DDMS) on the retinal surface after internal limiting membrane (ILM) abrasion in macular hole surgery.

METHODS

Institutional experimental study was performed in 11 eyes. All eyes underwent ILM abrasion in the operating room with a DDMS for macular hole repair as an alternative to traditional ILM peeling. Three human donor eyes underwent an identical procedure in the laboratory. Retinal tissues were removed by ILM abrasion with a DDMS during vitrectomy for macular hole repair and retinal tissues remaining in human donor eyes. Main outcome measures were microscopic and immunohistological characteristics of instrument tip tissues and retinal structure after ILM abrasion.

RESULTS

The tips of the Tano DDMS showed evidence of cellular membranes and ILM removal. The retinas showed distinct areas of lamellar ILM removal without penetration of the retinal nerve fiber layer (RNFL).

CONCLUSIONS

Application of the Tano DDMS instrument is sufficient to remove membranes from the surface of the ILM and layers of the ILM without disruption of the underlying RNFL. Internal limiting membrane abrasion can be a useful and effective alternative to complete ILM removal for macular surgery.

A simple method for in vivo labelling of infiltrating leukocytes in the mouse retina using indocyanine green dye

We have developed a method to label and image myeloid cells infiltrating the mouse retina and choroid in vivo, using a single depot injection of indocyanine green dye (ICG). This was demonstrated using the following ocular models of inflammation and angiogenesis: endotoxin-induced uveitis, experimental autoimmune uveoretinitis and laser-induced choroidal neovascularization model. A near-infrared scanning ophthalmoscope was used for in vivo imaging of the eye, and flow cytometry was used on blood and spleen to assess the number and phenotype of labelled cells. ICG was administered 72 h before the induction of inflammation to ensure clearance from the systemic circulation. We found that in vivo intravenous administration failed to label any leukocytes, whereas depot injection, either intraperitoneal or subcutaneous, was successful in labelling leukocytes infiltrating into the retina. Progression of inflammation in the retina could be traced over a period of 14 days following a single depot injection of ICG. Additionally, bright-field microscopy, spectrophotometry and flow cytometric analysis suggest that the predominant population of cells stained by ICG are circulating myeloid cells. The translation of this approach into clinical practice would enable visualization of immune cells in situ. This will not only provide a greater understanding of pathogenesis, monitoring and assessment of therapy in many human ocular diseases but might also open the ability to image immunity live for neurodegenerative disorders, cardiovascular disease and systemic immune-mediated disorders.

Summary: We show here that peripheral leukocytes can be labelled with ICG in vivo and then directly imaged as they invade the retina after inflammatory stimuli.

Idiopathic epiretinal membrane

BACKGROUND

Idiopathic epiretinal membrane (iERM) is a fibrocellular membrane that proliferates on the inner surface of the retina at the macular area. Membrane contraction is an important sight-threatening event and is due to fibrotic remodeling.

METHODS

Analysis of the current literature regarding the epidemiology, clinical features, and pathogenesis of iERM and fibrotic tissue contraction.

RESULTS

Epidemiologic studies report a relationship between iERM prevalence, increasing age, and posterior vitreous detachment. Clinically, iERM progresses through different stages characterized by an increased thickness and wrinkling of the membrane. Pathophysiologically, iERM formation is a fibrotic process in which myofibroblast formation and the deposition of newly formed collagens play key roles. Anomalous posterior vitreous detachment may be a key event initiating the formation of iERM. The age-related accumulation of advanced glycation end products may contribute to anomalous posterior vitreous detachment formation and may also influence the mechanical properties of the iERM.

CONCLUSION

Remodeling of the extracellular matrix at the vitreoretinal interface by aging and fibrotic changes, plays a significant role in the pathogenesis of iERM. A better understanding of molecular mechanisms underlying this process may eventually lead to the development of effective and nonsurgical approaches to treat and prevent vitreoretinal fibrotic diseases.

In vivo biocompatibility of a new cyanine dye for ILM peeling

PURPOSE

To investigate the biocompatibility of the new cyanine dye: 3,3'-Di-(4-sulfobutyl)-1,1,1',1'-tetramethyl-di-1H-benz[e]indocarbocyanine (DSS) as a vital dye for intraocular application in an in vivo rat model and to evaluate the effects of this dye on retinal structure and function.

METHODS

DSS at a concentration of 0.5% was applied via intravitreal injections to adult Brown Norway rats with BSS serving as a control. Retinal toxicity was assessed 7 days later by means of retinal ganglion cell (RGC) counts, light microscopy, optical coherence tomography (OCT), and electroretinography (ERG).

RESULTS

No significant decrease in RGC numbers was observed. No structural changes of the central retina were observed either in vivo (OCT) or under light microscopy. ERGs detected a temporary reduction of retinal function 7 days after injection; this was no longer evident 14 days after injection.

CONCLUSIONS

DSS showed good biocompatibility in a well-established experimental in vivo setting and may be usable for intraocular surgery as an alternative to other cyanine dyes. In contrast to indocyanine green, it additionally offers fluorescence in the visual spectrum. Further studies with other animal models are needed before translation into clinical application.

Evaluation of secondary surgery to enlarge the peeling of the internal limiting membrane following the failed surgery of idiopathic macular holes

The aim of the present study was to evaluate the clinical results of pars plana vitrectomy (PPV) combined with the surgical enlargement of internal limiting membrane (ILM) peeling in patients who had previously undergone failed idiopathic macular hole (IMH) surgery. In the study, 134 eyes from 130 IMH patients who had received PPV combined with ILM peeling surgery (2 disk diameters) were analyzed. Within this cohort, 14 eyes had IMHs that were not closed, of which 13 eyes underwent a second surgery involving enlargement of the ILM peeling. The extent of the ILM peeling was increased to the vascular arcades of the posterior fundus in the secondary surgery. Of the 13 eyes that underwent secondary surgery, five were in stage III and nine were in stage IV. The second surgery successfully achieved IMH closure in 61.5% (8/13) of the eyes. The IMH was completely closed following surgery and the logMAR vision increased from 0.98 to 0.84 (P=0.013) in the 8 successfully treated cases. The surgical enlargement of ILM peeling closed the IMHs and improved vision in the majority of patients. In addition, the procedures were safe. Therefore, the results of the present study indicate that enlargement of ILM peeling may be an effective therapy for patients who have previously undergone the failed surgical correction of an IMH.

Predicting visual outcome following surgery for idiopathic macular holes

Since Kelly and Wendel [Arch Ophthalmol 1991;109:654-659] first reported successfully treating macular holes (MHs) using pars plana vitrectomy in 1991, MH surgery has been constantly improved. For example, introducing the removal of the internal limiting membrane considerably increased the closure rate of MHs, and the advent of microincision vitrectomy surgery reduced surgical trauma and decreased patient discomfort after surgery. As modern MH surgery can achieve a higher anatomical success rate and alleviate patients' postoperative distress, postoperative visual outcomes have lately become the primary concern. Informing patients of the expected visual acuity and visual improvement before surgery is ideal, but predicting postoperative visual outcomes is difficult because a large number of factors are associated with them. In this paper, we review previous studies and provide accumulating evidence for the relationship between individual prognostic factors and visual outcomes after MH surgery.

Changes of parafoveal retinal nerve fiber layer thickness analyzed by spectral-domain optical coherence tomography after pars plana vitrectomy

PURPOSE

To use spectral-domain optical coherence tomography to evaluate the postoperative retinal nerve fiber layer (RNFL) thickness changes in eyes undergoing vitrectomy.

METHODS

This is a retrospective study of 44 patients (44 eyes) who underwent monocular vitrectomy for an epiretinal membrane (19 eyes), macular hole (12 eyes), or vitreous hemorrhage (13 eyes). Quantitative analysis of the peripapillary RNFL by spectral-domain optical coherence tomography was performed before surgery and for 6 months postoperatively on both eyes.

RESULTS

Mean patient age was 62.72 ± 9.11 years. Mean preoperative RNFL thickness did not differ significantly between vitrectomized eyes (88.33 ± 13.23 μm) and nonvitrectomized fellow eyes (87.49 ± 13.18 μm; P > 0.05). In vitrectomized eyes, the preoperative mean RNFL thickness in the superior quadrant was significantly different from that at 6 months after surgery (P = 0.02). Vitrectomized eyes with a macular hole showed significant changes in the mean RNFL thickness in the inferior quadrant (P = 0.04).

CONCLUSION

Retinal nerve fiber layer thickness was reduced in some of the quadrants of the vitrectomized eye during the 6-month postoperative follow-up period. Spectral-domain optical coherence tomography can be clinically useful for detection of localized RNFL defects in patients who underwent vitrectomy. Future prospective studies with more patients and longer follow-up duration are required.

The retinal biocompatibility of dyes in the ex vivo model of the isolated superfused vertebrate retina

BACKGROUND

Peeling of the internal limiting membrane or epiretinal membranes is a successful principle in macular surgery to achieve a functional benefit. Different dyes are used to facilitate the identification of intraocular tissues. The aim of our work was to investigate the retinal tolerance to the different dyes and their solvent carriers to provide valuable data for surgeons in handling for an optimal intraoperative use.

METHODS

Using the ex vivo model of the isolated superfused vertebrate retina technique, the effects of the dyes were tested on human and bovine retinal function. The retinas were perfused with an oxygen preequilibrated standard solution. The electroretinogram (ERG) was recorded using Ag/AgCl electrodes. After recording stable ERG amplitudes, the dyes brilliant blue G, indocyanine green, trypan blue, patent blue, triamcinolone and their solvent carriers were investigated.

RESULTS

Reductions of the ERG amplitudes were found for each tested dye. The effects after application of the dyes were dependent on time and concentration of the applied dyes, which were different for each dye.

CONCLUSION

In part, the ERG has shown strong effects already after a short period of dye application. Surgeons who rely on the intraocular use of the dyes should keep in mind our findings, and the use of some dyes should be limited to selected cases. The well-considered use of the dyes by the surgeons could lead to a better functional outcome and avoid a possible harmful outcome of the surgery after mishandling.

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.

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.

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.

A review of indocyanine green fluorescent imaging in surgery

The purpose of this paper is to give an overview of the recent surgical intraoperational applications of indocyanine green fluorescence imaging methods, the basics of the technology, and instrumentation used. Well over 200 papers describing this technique in clinical setting are reviewed. In addition to the surgical applications, other recent medical applications of ICG are briefly examined.

Tempol protects against intravitreous indocyanine green-induced retinal damage in rats

PURPOSE

Indocyanine green (ICG) has been widely used as a vital dye for macular surgery. However, ICG can be toxic to retinal cells. Here we evaluate whether tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a free radical scavenger, can protect against ICG-induced retinal damage in rats.

METHODS

Brown Norway rats received intravitreal injections of ICG 0.5 % or BSS as controls. Tempol (20 mg/kg BW) or PBS as a control was administered intraperitoneally 24 h and 30 min before ICG and once daily for 7 consecutive days. Tempol was detected in the retina using electron paramagnetic resonance (EPR) spectroscopy. One week after ICG injections, the effects of tempol on retinal toxicity were assessed by retinal ganglion cell (RGC) back-labeling and by light microscopy. Electroretinography (ERG) was performed after 1 and 2 weeks.

RESULTS

ICG administration reduced RGC numbers by 17 % (1,943 ± 45 vs. 2,342 ± 31 RGCs/mm(2)). Tempol treatment rescued RGCs in a significant manner (2,258 ± 36, p < 0.01) and diminished morphological changes detected by light microscopy. ICG-injected eyes showed a significant reduction of ERG potentials only in PBS-treated animals (V(max) 530 ± 145 µV vs. 779 ± 179 µV, p = 0.0052), but not in the tempol-treated group.

CONCLUSIONS

Tempol significantly attenuates ICG-induced toxicity in rat retinas and may therefore be considered for further evaluation as accompanying treatment in ICG-assisted chromovitrectomy.

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.

The role of the optical coherence tomography in identifying shape and size of idiopathic epiretinal membranes

AIM

Currently, the border of idiopathic epiretinal membranes (iERM) is outlined intraoperatively using vital dyes. Therefore, the authors set out to investigate the role of the preoperative retinal thickness map (RTM) of the optical coherence tomography (OCT) in identifying the shape and the size of the iERMs.

Methods

15 eyes of 15 patients with iERM who underwent vitrectomy with indocyanine green-assisted membrane peeling were included in this study. The authors analysed the intraoperative fundus images and preoperative Cirrus HD-OCT to detect the shape and the size of the iERM as well as the shape and the size of each thickness-indicating colour (white, red, orange and yellow) on the RTM, respectively. The correlation of areas and morphologic characteristics between both groups was explored.

Results

Analysis of iERM morphologic characteristics (shape) showed a similarity between the iERM contour and the corresponding RTM in 13 cases (86.6%). Furthermore, retinal folds were found in six iERMs and in their corresponding RTMs. Analysis of iERM size (area) revealed a positive correlation between the iERM area and each studied coloured area in RTM. The most significant correlation was between iERM and the red area (440–480 μm; r=0.87, p<0.0001).

Conclusion

The iERM-related retinal folds are clearly distinguishable on the HD-OCT. The red area in RTM representing the 440–480 μm retinal thickness can be a reliable predictor of the extent and the shape of the iERM.

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.

Outcomes of 23-gauge pars plana vitrectomy and internal limiting membrane peeling with brilliant blue in macular hole

Purpose:

The evaluation of anatomic and visual outcomes in macular hole cases treated with internal limiting membrane (ILM) peeling, brilliant blue (BB), and 23-gauge pars plana vitrectomy (PPV).

Materials and methods:

Fifty eyes of 48 patients who presented between July 2007 and December 2009 with the diagnosis of stage 2, 3, or 4 macular holes according to Gass Classification who had undergone PPV and ILM peeling were included in this study. Pre- and postoperative macular examinations were assessed with spectral-domain optical coherence tomography. 23 G sutureless PPV and ILM peeling with BB was performed on all patients.

Results:

The mean age of patients was 63.34 ± 9.6 years. Stage 2 macular hole was determined in 17 eyes (34%), stage 3 in 24 eyes (48%), and stage 4 in 9 eyes (18%). The mean follow-up time was 13.6 ± 1.09 months. Anatomic closure was detected in 46/50 eyes (92%), whereas, in four cases, macular hole persisted and a second operation was not required due to subretinal fluid drainage. At follow-up after 2 months, persistant macular hole was detected in one case and it was closed with reoperation. At 12 months, an increase in visual acuity in 41 eyes was observed, while it remained at the same level in six eyes. In three eyes visual acuity decreased. There was a postoperative statistically significant increase in visual acuity in stage 2 and 3 cases (P < 0.05), however, no increase in visual acuity in stage 4 cases was observed.

Conclusion:

PPV and ILM peeling in stage 2, 3, and 4 macular hole cases provide successful anatomic outcomes, however, in delayed cases, due to photoreceptor loss, it has no effect on functional recovery. BB, used for clarity of ILM, may be beneficial due to its low retinal toxicity.

Formation of near-infrared fluorescent nanoparticles for medical imaging

Aims: Indocyanine green (ICG) is a US FDA-approved near-infrared fluorescent, water-soluble dye used for diagnostics in vitro and in vivo. The aim of this study was to develop insoluble nanoparticles based on a cationic polymer, ICG and a targeting molecule. The particles are intended for oral administration in the colon, having fluorescence in near-infrared, thus enabling remote detection. Materials & methods: An aqueous dispersion of particles formed from Eudragit-RS by simple precipitation method possessing a mean size of approximately 100 nm and zeta potential of +16 mV was produced. Results: These particles are capable of binding both ICG and fluorescein isothiocyanate–IgG via noncovalent interactions. These composite particles retain the emission characteristics of the fluorescent precursors and also exhibit potential specific recognition ability. The particles were stable in intestinal fluid and are composed only of materials that are FDA approved. Conclusion: The nanoparticles may be suitable for in vivo imaging and therapy by oral delivery systems.

Value of internal limiting membrane peeling in surgery for idiopathic macular hole and the correlation between function and retinal morphology

Idiopathic macular hole is characterized by a full thickness anatomic defect in the foveal retina leading to loss of central vision, metamorphopsia and a central scotoma. Classic macular hole surgery consists of vitrectomy, posterior vitreous cortex separation and intraocular gas tamponade, but during the past decade focus has especially been on internal limiting membrane (ILM) peeling as adjuvant therapy for increasing closure rates. With increasing use of ILM peeling and indocyanine green (ICG) staining, which is used for specific visualization of the ILM, concerns about the safety of the procedure have arisen. At present, it is not known whether ICG-assisted ILM peeling potentially reduces the functional outcome after macular hole surgery. The purpose of the present PhD thesis was to examine whether ICG-assisted ILM peeling offers surgical and functional benefit in macular hole surgery. We conducted a randomized clinical trial including 78 pseudophakic patients with idiopathic macular hole stages 2 and 3. Patients were randomly assigned to macular hole surgery consisting of (i) vitrectomy alone without instrumental retinal surface contact (non-peeling), (ii) vitrectomy plus 0.05% isotonic ICG-assisted ILM peeling or (iii) vitrectomy plus 0.15% trypan blue (TB)-assisted ILM peeling. Morphologic and functional outcomes were assessed 3, 6 and 12 months after surgery. The results show that surgery with ILM peeling, for both stages 2 and 3 macular holes, is associated with a significantly higher closure rate than surgery without ILM peeling (95% versus 45%). The overall functional results confirm that surgery for macular hole generally leads to favourable visual results, with two-thirds of eyes regaining reading vision (>or=20/40). Macular hole surgery can be considered a safe procedure with a low incidence of sight-threatening adverse events; the retinal detachment rate was 2.2%. Visual outcomes in eyes with primary hole closure were not significantly different between the intervention groups; however, for the stage 2 subgroup with primary macular hole closure, there was a trend towards a better mean visual acuity in the non-peeling group (78.2 letters) compared to the ICG-peeling group (70.9 letters), p = 0.06. Performing repeated macular hole surgery was associated with a significant reduction in functional outcome indicating that primary focus should be on closing the macular hole in one procedure. Morphological studies of closed macular holes with contrast-enhanced optical coherence tomography (OCT) found thinning and discontinuity of the central photoreceptor layer matrix that were highly specific for predicting the likelihood of an eye having regained reading vision 12 months after macular hole surgery. Additionally, healing after macular hole surgery appeared to begin with the contraction of the inner aspect of the retina, forming a roof over a subfoveal fluid-filled cavity, and to end with a gradual restoration of the anatomy in the outer layers of the retina at the junction of the photoreceptor inner and outer segments. We found the more intact this structure was on contrast-enhanced OCT 3 months after macular hole surgery, the better the visual acuity after 12 months, whereas late rather than early resolution of subfoveal fluid had no impact on final visual outcome. The use ILM peeling and intraoperative dyes did not have any functionally important effects on postoperative macular structure. Based on the above findings, we conclude that ILM peeling should be performed in all cases of full thickness macular hole surgery. The use of 0.05% intraoperative isotonic ICG with short exposure time appears to be a safe alternative in stage 3 macular hole surgery, whereas a slight reduction in functional potential not can be excluded when performing 0.05% isotonic ICG-assisted ILM peeling in stage 2 macular hole surgery.