Indocyanine green effect on cultured human retinal pigment epithelial cells: implication for macular hole surgery

Pre- and postoperative OCT features and surgical outcomes of advanced retinitis pigmentosa with macular hole: case series and literature review

BACKGROUND

Macular hole (MH) is a rare complication of retinitis pigmentosa (RP) and has an adverse impact on residual visual function. At present, the underlying mechanisms are not fully understood and surgical experience is limited.

METHODS

We reviewed the medical records and optical coherence tomography (OCT) scans in a cohort of eight eyes of seven RP patients with MH in order to report their OCT features and vitreoretinal surgical prognosis.

RESULTS

This study includes four lamellar macular holes (LMHs) and four full-thickness macular holes (FTMHs). Pre-operative OCT revealed other macular abnormalities in all eyes, such as epiretinal membrane (ERM), cystoid macular edema (CME), lamellar hole-associated epiretinal proliferation (LHEP) and vitreoretinal traction. MH progression and subjective vision worsening were noted in one LMH eye during a seven-month follow-up. All holes closed after vitrectomy with internal limiting membrane (ILM) peeling. At final follow-up, one eye had improved vision and seven eyes remained stable compared to baseline.

CONCLUSIONS

The occurrence of MH in RP is accompanied by various imaging characteristics, such as ERM, CME and LHEP, suggesting a multifactorial pathogenesis. Considering poor vision in most RP patients with potentially progressive MH, surgery appears to be effective in maintaining or improving the central vision in a period of time. Thus, vitrectomy should be performed as soon as possible and flap-assisted techniques or episcleral surgeries are needed for some special cases.

Pars Plana Vitrectomy in Inherited Retinal Diseases: A Comprehensive Review of the Literature

Inherited retinal diseases (IRDs) are a group of clinically and genetically heterogeneous disorders that may be complicated by several vitreoretinal conditions requiring a surgical approach. Pars plana vitrectomy (PPV) stands as a valuable treatment option in these cases, but its application in eyes with such severely impaired chorioretinal architectures remains controversial. Furthermore, the spreading of gene therapy and the increasing use of retinal prostheses will end up in a marked increase in demand for PPV surgery for IRD patients. The retinal degeneration that typically affects patients with hereditary retinal disorders may influence the execution of the surgery and the expected results. Considering the importance of PPV application in IRD-related complications, it is fundamental to try to understand from the literature what is adequate and safe in posterior eye segment surgery. Use of dyes, light toxicity, and risk of wounding scar development have always been themes that discourage the execution of vitreoretinal surgery in already impaired eyes. Therefore, this review aims to comprehensively summarize all PPV applications in different IRDs, highlighting the favorable results as well as the potential precautions to consider when performing vitreoretinal surgery in these eyes.

Safety Profile of Lutein- Versus Triamcinolone Acetonide-Based Vitreous Staining

Purpose

To assess the safety profile of a new lutein-based vitreous dye (LB-VD) formulation compared with various triamcinolone acetonide (TA) formulations with and without subsequent exposure to perfluorodecalin (PFD) in vitro.

Methods

Human adult retinal pigment epithelial cells (ARPE-19) were treated with the following formulations: undiluted preserved TA (TA-BA), diluted preserved TA (D-TA-BA), preservative-free TA (TA-PF), and LB-VD. First, cell tolerability was evaluated with MTT, LDH, and ATPlite assays after 1, 5, and 30 minutes of exposure to each tested formulation. Then, cells were sequentially exposed to formulations and PFD. After 24 hours of exposure to PFD, cell tolerability was evaluated through MTT and ATPlite assays.

Results

Among the formulations tested, LB-VD showed the highest levels of cell viability, cell metabolism, and cell proliferation and induced the lowest release of LDH, whereas the TA-based formulations demonstrated a cytotoxic effect on ARPE-19 cells in vitro. After subsequent 24-hour exposure to PFD, a greater reduction of cell viability was noted for all the formulations; however, this reduction was not significant only for the combination LB-VD-PFD, which was the best tolerated condition.

Conclusions

LB-VD showed a better safety profile compared with all TA-based formulations, even when used in combination with PFD.

Translational Relevance

In surgical practice, LB-VD may be preferred to TA-based formulations for vitreous staining in the light of its more favorable safety profile.

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.

Central Retinal Thickness and Visual Acuity Outcomes After Vitrectomy for Epiretinal Membrane With and Without Internal Limiting Membrane Peel

Purpose:

This work compares best-corrected visual acuity (BCVA) and central retinal thickness (CRT) outcome measures following pars plana vitrectomy (PPV) with and without internal limiting membrane (ILM) peel for epiretinal membrane (ERM).

Methods:

A retrospective cohort study was conducted of 114 eyes of 114 patients with visually significant ERM undergoing PPV with membrane peel (PPV/MP) at a single institution. CRT measurements were collected from Heidelberg and Zeiss spectral-domain optical coherence tomography imaging units. Results compared preoperative and postoperative CRT and BCVA among patients with at least 60 days of follow-up.

Results:

A total of 114 eyes with ERM met the inclusion criteria. Eighty-one eyes (71%) underwent PPV/MP with ILM peel and 33 eyes (29%) underwent PPV/MP without ILM peel. There was no statistically significant difference between preoperative CRT between the 2 study groups ( P = .95). The mean follow-up time of eyes undergoing PPV/MP without ILM peel and with ILM peel was 391 days and 319 days, respectively. There was no statistical difference in the mean reduction of CRT between the 2 groups ( P = .470). Both groups had improvement of BCVA following surgery and there was no statistical difference in final logMAR visual acuity when comparing the 2 groups ( P = .738).

Conclusions:

There was an overall improvement of CRT and BCVA among patients undergoing PPV/MP for ERM with or without ILM peel. There was no statistically significant difference in the final BCVA or CRT between the 2 groups.

Epiretinal large disc of blue-stained lyophilized amniotic membrane to treat complex macular holes: a 1-year follow-up

PURPOSE

To report the long-term outcomes of large diameter epiretinal lyophilized amniotic membranes (lAMs) in recurrent or persistent macular holes (MHs) with or without rhegmatogenous retinal detachment (RRD), in a prospective interventional case series.

METHODS

Ten eyes of 10 patients underwent pars plana vitrectomy for MH-associated RRD (n = 5) or persistent MH without RRD (n = 5), in a university Hospital. A 3 or 4 mm diameter disc of lAM, stained with 0.06% trypan blue, was inserted with a catheter through a sclerotomy and positioned over the MH. Gas or silicone-oil tamponade was used. At 1 year, the main outcome was anatomic success defined as complete MH closure. Secondary outcomes were best corrected visual acuity (BCVA) recovery, changes in ellipsoid zone (EZ) and external limiting membrane (ELM) defects, complications. Mean follow-up was 13.8 ± 2.9 months (range, 12-18).

RESULTS

Mean baseline data were minimum and maximum diameters, respectively, 945 ± 330 and 1507 ± 717 μm; axial length 26.58 ± 3.38 mm; and number of prior surgeries 1.4 ± 0.96. At 1 year, anatomic success was achieved in eight eyes (80%), and two had reduced diameter of MH. All RRDs were reattached without recurrence. Mean logMAR BCVA improved from 1.92 ± 0.58 to 1.17 ± 0.57 (p < 0.001), with nine eyes (90%) achieving ≥0.3 logMAR improvement. Mean EZ and ELM defects decreased (p = 0.004, p = 0.003, respectively). Postoperative complications were RRD (n = 1) reattached by subsequent surgery, lAM slightly retracted under silicone (n = 1), foveal atrophy after early lAM displacement (n = 1).

CONCLUSION

A 1-year follow-up highlighted that epiretinal large discs of blue-stained lAM can help safely close refractory MHs, and provide satisfactory visual recovery.

Customized Color Settings of Digitally Assisted Vitreoretinal Surgery to Enable Use of Lower Dye Concentrations During Macular Surgery

Purpose

This study evaluated the color contrast ratio (CCR) of the internal limiting membrane (ILM) using different color settings of digitally assisted vitreoretinal surgery (DAVS) with different indocyanine green (ICG) concentrations.s

Methods

This is a prospective comparative observational study. Consecutive patients that underwent 25G vitrectomy and ILM peeling using a standard operating microscope (SOM) (25 eyes), DAVS Ver. 1.1 (12 eyes), or DAVS Ver. 1.3 (13 eyes) were enrolled. The SOM and DAVS Ver. 1.1 groups used 0.075% ICG, and the DAVS Ver. 1.3 group used 0.025% ICG. In DAVS Ver. 1.1, macular CCR was compared between four different presets in the red, green, and blue channels: Default (Red (R) 100%, Green (G) 100%, and Blue (B) 100%); Preset 1 (R 20%, G 100%, B 100%); Preset 2 (R 80%, G 80%, B 100%), and Preset 3 (R 85%, G 100%, B 90%). In DAVS Ver. 1.3, macular CCR was evaluated using two different customized settings that modified the hue and saturation: Customized Setting 1 (R 86, G 100, B 100%, Hue +2°, Saturation 90%, Gamma 1.2) and Customized Setting 2 (R 90, G 100, B 100%, Hue +20°, Saturation 100%, Gamma 0.9). All patients underwent ophthalmologic examinations including BCVA at baseline and at 12 months.

Results

In DAVS Ver. 1.1, macular CCR was highest in Preset 3 (P &lt; 0.01). The CCR of Customized Setting 2 of DAVS Ver. 1.3 using 0.025% ICG did not differ from that of Preset 3 in DAVS Ver. 1.1 using 0.075% ICG. Furthermore, there was no significant difference in BCVA between the Customized Setting 2 of DAVS Ver. 1.3 with 0.025% ICG and the Preset 3 of DAVS Ver. 1.1 with 0.075% ICG groups at baseline and at 12 months (P &gt; 0.05, respectively).

Conclusion

Customized DAVS settings enabled surgeons to use a 3-fold lower ICG concentration in ILM peeling.

Inner retinal structure and visual function after idiopathic epiretinal membrane surgery with and without brilliant blue G

PURPOSE

Vital dyes are frequently used to visualize the internal limiting membrane (ILM) of the neuroretina. This study evaluated and compared the microstructure of the inner retina and visual function with and without brilliant blue G (BBG) staining for ILM peeling during idiopathic epiretinal membrane (ERM) surgery.

STUDY DESIGN

Retrospective, consecutive, interventional case series.

METHODS

Fifty-five patients (55 eyes) with ERM underwent ILM peeling without dyes (non-dye group) and 55 patients (55 eyes) underwent ILM peeling with BBG staining (BBG group). The logMAR visual acuity (VA) and ganglion cell complex (GCC) thickness were measured using optical coherence tomography at baseline and 12 months after surgery.

RESULTS

LogMAR VA improved significantly in both groups at 12 months and the BBG group tended to be better than the non-dye group but with no significant difference between the groups (unpaired t-test, P = 0.490). The average GCC thickness significantly decreased in both groups; however, there was no difference in the rates of change in GCC thickness between the groups. The ratio of GCC thickness to total retinal thickness (%) was significantly higher in the BBG group in the superior quadrant at 12 months postoperatively (P = 0.010).

CONCLUSION

BBG-assisted ERM surgery resulted in better visual improvement and fewer structural changes in the inner retinal layers. BBG-assisted ILM peeling is safe both functionally and anatomically.

The Influence of Crescent-Shaped Selective Internal Limiting Membrane Staining on Vital Dye Toxicity in Temporal Inverted Flap Technique

Purpose: To investigate the macular function and morphology after temporal inverted internal limiting membrane (ILM) flap technique with and without staining of the ILM flap in contact with the retinal pigment epithelium (RPE).Materials and Methods: This retrospective study included 30 patients with idiopathic macular hole (MH), who underwent 27 G vitrectomy and temporal inverted ILM flap technique with brillant blue G (BBG) assisted ILM staining. In Group 1 (n = 16), a large bubble of perfluorocarbon liquid (PFCL) measuring approximately 6-disc diameters was used to cover the hole and central part of the ILM flap whereas in Group 2 (n = 14), only a small drop of PFCL to merely cover the MH was used. Complete ophthalmic examination including microperimetry (MP), optical coherence tomography (OCT) was performed preoperatively, 6 months after surgery.Results: MH closure was achieved in all the eyes in both groups. The sizes of ellipsoid zone (EZ) and external limiting membrane (ELM) defect significantly decreased after surgery relative to the baseline width in both groups (p < .05 for all). The mean improvement in visual acuity (p = .896) and retinal sensitivity was similiar between groups (p = .409). Accordingly, the postoperative mean lengths of the EZ (p = .254) and ELM disruption (p = .406) on OCT scans were similiar between groups. However, 3 of the eyes in Group 2 developed cystoid macular edema between postoperative month-1 and month-6.Conclusion: The crescent-shaped selective staining of the ILM flap could prevent prolonged retinal toxicity of vital dyes in inverted ILM flap technique. Further studies involving larger number of patients with longer follow up are needed to determine the impact of this technique in the management of vital dye toxicity.

Central scotoma after indocyanine green assisted fovea-sparing internal limiting membrane peeling

Purpose

To report a case with myopic traction maculopathy (MTM) that underwent fovea-sparing internal limiting membrane (ILM) peeling and developed a central scotoma with a nasal visual field defect postoperatively.

Observations

A 63-year-old man diagnosed with foveoschisis and a small outer lamellar macular hole underwent 25-gauge, 3-port pars plana vitrectomy and fovea-sparing ILM peeling using indocyanine green (ICG) staining. One year after the vitrectomy, optical coherence tomography (OCT) revealed a resolution of the macular retinoschisis and an intact ellipsoid zone at the fovea. However, macular edema was present over the area of the residual ILM, and the visual acuity had worsened to 20/200. Goldmann perimetry showed a central scotoma and a constriction of the nasal visual field. OCT angiography detected abnormal blood flow in the inner retina corresponding to the area of the residual foveal ILM. The multifocal electroretinograms were reduced in the central area.

Conclusion

The findings suggest that functional abnormalities of the fovea induced by ICG toxicity may have been manifested by a central scotoma. Therefore, surgeons need to consider the toxic effects of dyes such as ICG.

Two cases with retinitis pigmentosa that developed severe retinal atrophy long after vitreo-retinal surgery

PURPOSE

To report two cases with retinitis pigmentosa (RP) who underwent vitreo-retinal surgery and developed severe retinal atrophy.

OBSERVATIONS

Case 1 was a 36-year old man who underwent 20-gauge pars plana vitrectomy (PPV) for a macular hole (MH), and Case 2 was a 71-year-old man who also underwent 20-gauge PPV for an epiretinal membrane (ERM). During 13 years follow-up period, severe retinal atrophy developed near the macula that progressed rapidly and the best-corrected visual acuity (BCVA) was reduced to 1.1 logarithm of the minimum angle of resolution (logMAR) units in the MH case and to no light perception in the ERM case.

CONCLUSIONS AND IMPORTANCE

An unexpected severe retinal atrophy can develop long after vitreo-retinal surgery in RP patients.

Outer Retinal Healing After Internal Limiting Membrane Peeling in Diabetic Macular Oedema with Vitreomacular Interface Abnormality Using Three Different Dyes

Purpose: To evaluate the difference in ellipsoid zone and external limiting membrane (EZ/ELM) restoration after vitrectomy with internal limiting membrane (ILM) peeling in diabetic macular oedema with vitreomacular interface abnormalities (VMA DME) patients using 3 different dyes.Methods: Patients with type 2 diabetes mellitus and VMA DME indicated for ILM peelings were included. Disruption of the EZ/ELM was graded and compared among groups (preoperative and 6 months postoperative). Patients were divided into 3 groups according to the dye used: group A: indocyanine green (ICG); group B: trypan blue (TB); and group C: brilliant blue G(BBG).Results: Twenty-six eyes were included in group A, 29 eyes were included in group B, and 28 eyes were included in group C. Improvement in EZ/ELM integrity was observed in 34.6% of group A, 27.6% of group B, and 32.1 % of group C (p = .84). Deterioration of EZ/ELM integrity was observed in 19.2% of group A, 6.9% of group B and 0% of group C (p = .03).Conclusion: ICG resulted in a greater percentage of deteriorated EZ/ELM integrity at 6 months after surgery in cases with pre-treatment ELM interruption. Therefore, ICG should be used with caution in cases with ELM disruption, yet, further studies are recommended.

Idiopathic epiretinal membrane surgery: safety, efficacy and patient related outcomes

This review aims to give to the reader an overview selectively oriented on safety and efficacy of surgery, providing concise and direct answers about crucial questions of trainees and experts. Surgery for idiopathic epiretinal membrane (ERM) is a safe and effective procedure that can achieve long-term stable postoperative visual and anatomical improvement, with an overall low recurrence and complication rate. Young patients, with a short onset of symptoms and with better initial visual acuity achieve higher levels of visual outcome. The preoperative degree of metamorphopsia is the prognostic factor for their postoperative degree. Successful results may be obtained in eyes with specific optical coherence tomography criteria, such as thin ganglion cell layers, thin internal plexiform layer, longer photoreceptors outer segment, regular ellipsoid zone and cone outer segment tips line, and without ectopic inner foveal layer. Internal limiting membrane peeling demonstrates positive anatomical and functional outcomes, but final positions about its safety remain controversial.

Vital Dyes in Vitreomacular Surgery

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

Effect of brilliant Blue-G on cellular stress response in retinal pigment epithelial cells: In vitro

To assess the cellular stress evoked by exposure of Brilliant Blue-G (BBG), adult retinal pigment epithelial (ARPE-19) cells were treated with various dilutions of BBG in balanced salt solution plus (BSS-PLUS) with and without endoillumination (Alcon Constellation Vision System). The treatments lasted for acute periods of 2 and 5 min. MTT and presto blue assays were performed to assess the changes in cell viability; reactive oxygen species (ROS) production was quantified by DCFDA (dichlorofluorescin diacetate) assay, and the expression of inflammatory stress and endoplasmic reticulum (ER) genes were quantified by qPCR. We observed no reduction in cell viability at 2 min of dye treatment with and without endoillumination while at 5 min exposure, a reduction in cell viability at all concentrations of the dye was observed compared to control. Though there was an increase in ROS with endoillumination, it was insignificant. There was no change in the mRNA expression of TNF-α while that of GRP78, and inflammatory genes viz. IL-8, IL-1β showed a significant increase at 0.5 mg/ml dye with endoillumination. BBG reduced cell viability with increasing concentration and time. The undiluted concentration of the dye results in inflammatory stress compared to the diluted formulations. Interestingly, increased GRP78 at undiluted concentration indicates a protective response in cells exposed to light. However, further studies are needed to evaluate the effect of cellular stress on the visual outcome. We infer that the commercially available formulation of BBG is safe for the RPE, at the recommended dose for a short duration however its toxicity to other cell types need to be addressed.

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.

Perfluorocarbon liquid-assisted membrane staining and peeling technique for macular diseases

PURPOSE

A surgical technique is described that facilitates membrane peeling in patients with macular diseases by using small amounts of perfluorocarbon liquid (PFCL) and brilliant blue G (BBG) dye.

STUDY DESIGN

Retrospective cohort study.

METHODS

After placing about 1.0-1.5 cc PFCL on the macular area, BBG was applied with a 27-gauge blunt needle at the interface of PFCL and retina. The membrane peeling was performed under PFCL.

RESULTS

The amount of BBG dye with PFCL-assisted staining technique has the potential to be smaller than in conventional staining method. Since the displacement angle of the membrane during peeling procedures is considerably increased by PFCL, combined with its high specific gravity and interfacial tension, the risk of tearing the membrane during manipulation is reduced to a great extent. The postoperative visual function in patients with PFCL-assisted peeling was comparable to that of patients without PFCL-assisted peeling.

CONCLUSION

The PFCL-assisted technique enables sufficient membrane staining with minimal amounts of BBG dye, with tearing of the epiretinal membrane or internal limiting membrane being less likely than with the conventional method.

Toxicity and phototoxicity in human ARPE-19 retinal pigment epithelium cells of dyes commonly used in retinal surgery

PURPOSE

To compare, for the first time, systematically the toxicity and phototoxicity of dyes and dye combinations used in vitreoretinal surgery. The dyes were trypan blue, brilliant blue G, trypan blue + brilliant blue G, indocyanine green, bromophenol blue, bromophenol blue + brilliant blue G, and acid violet 17, in clinically used concentrations.

METHODS

Human ARPE retinal pigment epithelium cells were exposed to the dyes for 30 min. For phototoxicity, the cells were exposed for 15 min to high-intensity light from a light emitting diode source with an intensity similar to surgical conditions. Toxicity was assayed either directly after exposure to either dye alone or dye and light, or with a delay of 24 h.

RESULTS

None of the dyes or their combinations was toxic when cells were exposed to them at ambient light. Acid violet led to a reduction viability by 90% already immediately after light exposure. Bromophenol blue and its combination with brilliant blue G showed strong phototoxicity (reduction of viability by 83%) when assayed with delay. Indocyanine green with different agents to adjust osmolarity (balanced salt solution, glucose, and mannitol) was not found to be toxic.

CONCLUSION

The strong immediate phototoxicity of acid violet reflects its clinical toxicity. Bromophenol blue might also be disadvantageous for patient outcome because of its delayed phototoxicity. The other dyes (trypan blue, brilliant blue g, and indocyanine green) were not found to be toxic neither with exposure to ambient light nor after exposure to light of intensities used in surgery.

Comparisons of foveal thickness and slope after macular hole surgery with and without internal limiting membrane peeling

Background

We have shown that the foveal contour was asymmetrical after idiopathic macular hole (MH) closure by pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling. The purpose of this study was to determine whether these morphological changes differ in eyes after PPV without ILM peeling.

Methods

Ten eyes of 10 patients that underwent PPV without ILM peeling and 12 eyes of 11 patients with ILM peeling were studied. The MH in all eyes was <400 µm in diameter. Six months after the PPV, the macular thickness and foveal slope around the closed MH were determined by spectral-domain optical coherence tomography. The thickness of the ganglion cell complex was measured by another spectral-domain optical coherence tomography instrument >6 months after the surgery.

Results

The mean parafoveal retinal thickness in the non-peeled group was 367.1 µm in the nasal (N), 353.0 µm in the temporal (T), 366.9 µm in the superior (S), and 357.3 µm in the inferior (I) sectors. The T, S, and I sectors were significantly thicker than the corresponding sectors in the ILM peeled group (p=0.0008, 0.003, and 0.03, respectively). The mean ganglion cell complex was thicker not only in the N sector but also in the T sector in the non-peeled group. The mean retinal slopes in the non-peeled group (N, 40.2°; T, 37.6°; S, 41.2°; I, 39.5°) were flatter than those in the peeled group (N, 52.3°; T, 43.6°; S, 50.8°; I, 51.9°; p=0.009, 0.09, 0.008, and 0.017, respectively).

Conclusion

The symmetrical fovea after MH surgery in the non-ILM peeled eyes indicates that the asymmetrical fovea after ILM peeling was probably due to the ILM peeling.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Biocompatibility of the vital dye Acid Violet-17 on retinal pigment epithelial cells

Purpose

To examine the viability and differentiation of retinal pigment epithelial (RPE) cells after exposure to the vital dye Acid Violet-17 (AV-17).

Methods

Bovine RPE cells were incubated with AV-17 (0.0625–0.5 mg/mL) for 30 seconds or 5 minutes. Viability was determined by live/dead staining, cleaved CASP3 immunostainings, and MTT test. Actin cytoskeleton was visualized by Alexa 488-phalloidin. Immunocytochemistry was performed to determine the levels of ZO-1, CTNNB1, and KRT19.

Results

Exposure to AV-17 at the concentrations of 0.25–0.5 mg/mL resulted in a dose-dependent decrease in viability, the loss of ZO-1 from tight junctions, translocation of CTNNB1 into the cytoplasm and nucleus, disarrangement of the actin cytoskeleton, and a slight increase in KRT19.

Conclusion

AV-17 at a concentration <0.125 mg/mL is likely to be well tolerated by the RPE cells, whereas the concentrations from 0.25 mg/mL onward can reduce viability and induce dedifferentiation particularly after long-term exposure.

The hyper-fluorescent transitional bands in ultra-late phase of indocyanine green angiography in chronic central serous chorioretinopathy

BACKGROUND AND OBJECTIVES

Chronic central serous chorioretinopathy (CSCR) is regarded as a type of severe diffuse retinal pigment epitheliopathy. There is an atrophic tract at level of retinal pigment epithelium (RPE) due to hyper-permeability of choroidal vessels, along with photoreceptor (PR) atrophy. Indocyanine green angiography (ICGA) is considered a gold standard for diagnosis. The purpose of this work is to investigate the hyper-fluorescent transitional bands (HFTB) between hypo-fluorescent and normal regions of the retina in the ultra-late phase of ICGA in CSCR.

METHODS

26 chronic CSCR eyes and 12 relative normal eyes received spectral domain optical coherence tomography (SD-OCT), and ICGA at the 24th hour after indocyanine green (ICG) intravenous injection.

RESULTS

In the ultra-late phase, images showed homogenous fluorescence in all normal eyes. On the contrary, geographical hypofluorescent lesions with atrophy of RPE was noted in 26 chronic CSCR eyes. Moreover, HFTB with intact RPE and disrupted PR was detected in 20 out of 26 chronic CSCR eyes (76.9%).

CONCLUSIONS

The HFTB may indicate the early damage in chronic CSCR. Ultra-late ICGA can monitor not only metabolic status by endogenous melanin, but also membrane function in RPE by exogenous ICG molecule.

Indocyanine Green: Historical Context, Current Applications, and Future Considerations

BACKGROUND

Indocyanine green (ICG) is a dye used in medicine since the mid-1950s for a variety of applications in in cardiology, ophthalmology, and neurosurgery; however, its fluorescent properties have only recently been used in the intraoperative evaluation of tissue perfusion.

METHOD

A literature review was conducted on the characterization and employment of ICG within the medical field. Historical and current context of ICG was examined while also considering implications for its future use.

RESULTS

ICG is a relatively nontoxic, unstable compound bound by albumin in the intravascular space until rapid clearance by the liver. It has widespread uses in hepatic, cardiac, and ophthalmologic studies, and its use in analyzing tissue perfusion and identifying sentinel lymph nodes in cancer staging is gaining popularity.

CONCLUSIONS

ICG has myriad applications and poses low risk to the patient. Its historical uses have contributed to medical knowledge, and it is now undergoing investigation for quantifying tissue perfusion, providing targeted therapies, and intraoperative identification of neurovascular anatomy, ophthalmic structures, and sentinel lymph nodes. New applications of ICG may lead to reduction in postoperative wound-related complications, more effective ophthalmologic procedures, and better detection and treatment of cancer cells.

Retinal Damage Induced by Internal Limiting Membrane Removal

The internal limiting membrane (ILM), the basement membrane of the Müller cells, serves as the interface between the vitreous body and the retinal nerve fiber layer. It has a fundamental role in the development, structure, and function of the retina, although it also is a pathologic component in the various vitreoretinal disorders, most notably in macular holes. It was not until understanding of the evolution of idiopathic macular holes and the advent of idiopathic macular hole surgery that the idea of adjuvant ILM peeling in the treatment of tractional maculopathies was explored. Today intentional ILM peeling is a commonly applied surgical technique among vitreoretinal surgeons as it has been found to increase the rate of successful macular hole closure and improve surgical outcomes in other vitreoretinal diseases. Though ILM peeling has refined surgery for tractional maculopathies, like all surgical procedures it is not immune to perioperative risk. The essential role of the ILM to the integrity of the retina and risk of trauma to retinal tissue spurs suspicion with regard to its routine removal. Several authors have investigated the retinal damage induced by ILM peeling and these complications have been manifested across many different diagnostic studies.

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.

Long-term outcomes of 3 surgical adjuvants used for internal limiting membrane peeling in idiopathic macular hole surgery

PURPOSE

Indocyanine green (ICG), an adjuvant used for peeling of the internal limiting membrane (ILM) during vitreous surgery for idiopathic macular hole (MH), has been reported to be toxic, possibly affecting postoperative visual acuity. We compared the long-term outcomes (within 2 years) of brilliant blue G (BBG), ICG, and triamcinolone acetonide (TA).

PATIENTS AND METHODS

This study involved 97 eyes of 94 patients who underwent vitreous surgery for MH at the Yamagata University Hospital between June 2002 and November 2010. The surgical adjuvants used were BBG for 15 eyes, ICG for 61 eyes, and TA for 21 eyes. We compared the postoperative visual acuities, initial closure rates, final closure rates, and complications of the 3 groups.

RESULTS

In all 3 groups, the visual acuity significantly improved after surgery. The magnitude of the improvement at 2 years after surgery was significantly better in the BBG group than in the ICG group (Mann-Whitney test, P = 0.020). The postoperative visual acuity did not significantly differ between the BBG and TA groups (P = 0.627) or between the ICG and TA groups (P =0 .137). Thus, the surgery using BBG resulted in a significantly better outcome in visual acuity than did the surgery using ICG. The 3 groups did not differ in initial or final closure rates or in incidence of complications.

CONCLUSION

Analysis of the long-term outcomes of vitreous surgeries provided evidence that BBG is a useful adjuvant for ILM peeling.

Novel 'heavy' dyes for retinal membrane staining during macular surgery: multicenter clinical assessment

PURPOSE

  To evaluate the feasibility of two novel 'heavy' dye solutions for staining the internal limiting membrane (ILM) and epiretinal membranes (ERMs), without the need for a prior fluid-air exchange, during macular surgery.

METHODS

  In this prospective nonrandomized multicenter cohort study, the high molecular weight dyes ILM-Blue™ [0.025% brilliant blue G, 4% polyethylene glycol (PEG)] and MembraneBlue-Dual™ (0.15% trypan blue, 0.025% brilliant blue G, 4% PEG) were randomly used in vitrectomy surgeries for macular disease in 127 eyes of 127 patients. Dye enhanced membrane visualization of the ILM and ERMs, 'ease of membrane peeling', visually detectable perioperative retinal damage, postoperative best-corrected visual acuity (BCVA), dye remnants and other unexpected clinical events were documented by 21 surgeons.

RESULTS

  All surgeries were uneventful, and a clear bluish staining, facilitating the identification, delineation and removal of the ILM and ERMs, was reported in all but five cases. None of the surgeries required a fluid-air exchange to assist the dye application. BCVA at 1 month after surgery improved in 83% of the eyes in the MembraneBlue-Dual™ group and in 88% in the ILM-Blue™ group. No dye remnants were detected by ophthalmoscopy, and no retinal adverse effects related to the surgery or use of the dyes were observed.

CONCLUSION

  The 'heavy' dye solutions ILM-Blue™ and MembraneBlue-Dual™ can be injected into a fluid-filled vitreous cavity and may facilitate staining and removal of the ILM and/or ERMs in macular surgery without an additional fluid-air exchange.

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.

Effect of novel vital dyes on outer blood-retina barrier function in cultured human retinal pigment epithelium

PURPOSE

To assess tight junction (TJ) integrity in cultured human fetal retinal pigment epithelium (HFRPE) after exposure to clinically relevant novel vital dyes.

METHODS

HFRPE floater cells were harvested from RPE primary cultures of 4 donor eyes and seeded on polyester Transwell® for 4-6 weeks. The apical compartments of well-differentiated cultures were exposed to 0.005 mg/ml Coomassie violet R200 (CVR), methyl 2B (M2B) or Orange II. Periods of 30-300 s were chosen to mimic surgical exposure times, while 3 h was used for toxicity assays, with subsequent washout. Cell-cell junctions were studied by immunofluorescence (zonula occludens-1, ZO-1). Transepithelial electrical resistance (TER) was measured regarding blood-retina barrier (BRB) function.

RESULTS

At 4-6 weeks after confluence, HFRPE had grown into pigmented hexagonal monolayers with stable TER values (451-1,520 Ω·cm(2)). After 300-second dye treatments, a continuous ZO-1 signal was detected in all vital dye-treated groups 1.5 h after exposure, whereas trypsin controls showed patchy loss of the TJ stain. TER of CVR-, M2B- and Orange-II-treated groups had dropped 1.5 h after exposure to 148 ± 58.4, 162 ± 23.7 and 164 ± 18.5 Ω·cm(2), respectively, compared to 73 ± 44.9 Ω·cm(2) in positive controls. After 3 h of exposure to 0.005 mg/ml vital dyes in thick drops, TER maintained similar levels to those prior to exposure (90.8 ± 4.7% of the original values, 93.8 ± 6.5 and 91.9 ± 3.6%, respectively), together with no difference from the vehicle controls (94.8 ± 6.6%). TER values recovered in all groups to prior levels within 3 days.

CONCLUSION

Novel vital dyes (CVR, M2B and Orange II) caused no outer BRB function alteration.

Chromovitrectomy and the vitreoretinal interface

It still remains unclear to which extent the presence and the amount of retinal debris seen in internal limiting membrane (ILM) specimens harvested during macular surgery for macular holes or epiretinal membranes are related to the procedure of ILM peeling itself or to modifications of the surgical technique, such as application of vital dyes for visualization of the ILM, or to pathological conditions with epiretinal membrane formation at the vitreoretinal interface. The presence of cellular fragments on the retinal side of the removed ILM appears to be of multifactorial origin, and additional causes besides dye application need to be considered. However, morphological studies with evaluation of vital dyes are still of relevance and provide additional insights into the ultrastructure of the vitreoretinal interface and its interaction with adjuvants used during macular surgery. Chromovitrectomy is an emerging field in vitreoretinal surgery. It is of importance to better understand the tissue-dye interactions, which not only alter the mechanical properties of the tissue being stained, but may also have an impact on the functional result postoperatively.

Dyes for Eyes™: hydrodynamics, biocompatibility and efficacy of 'heavy' (dual) dyes for chromovitrectomy

As epiretinal membranes (ERMs), the internal limiting membrane (ILM) and the vitreous cortex are essentially transparent tissues, or translucent structures, nontraumatic removal may be challenging in various types of macular surgery. Vital dyes stain these thin tissues, thus allowing for better visualization of these structures during vitrectomy and selective 'membrane peeling' from the underlying retina. To avoid swirling of the dye within the fluid-filled vitreous cavity, and to better target the dye onto the macula, a fluid-air exchange is commonly performed. However, this may jeopardize visualization of the macula during peeling due to clouding of the posterior lens capsule, and may lead to postoperative visual field defects. Recently, a new dye solution for staining the ERM and ILM simultaneously has been developed that circumvents the need for fluid-air exchange, i.e. MembraneBlue-Dual™. This paper will focus on the hydrodynamics and biocompatibility of this 'heavy' dual dye and its efficacy for staining of the ILM and/or ERMs during posterior segment surgery in a multicenter clinical setting.

Effects of indocyanine green staining on the recovery of visual acuity and macular morphology after macular hole surgery

PURPOSE

To evaluate whether indocyanine green (ICG)-assisted internal limiting membrane peeling affects visual outcome and macular morphologic changes in spectral-domain optical coherence tomography images after macular hole (MH) surgery.

METHODS

A retrospective analysis was performed of 34 eyes in 34 patients who had undergone surgical treatment for MH. Best-corrected visual acuity (BCVA) and optical coherence tomography parameters including central foveal thickness, length of the external limiting membrane (ELM) defect, and length of the inner segment and outer segment (IS/OS) defect were analyzed pre- and postoperatively.

RESULTS

The eyes were divided into 2 groups based on ICG use (ICG+/-). The changes in BCVA did not differ significantly between the 2 groups at 6 months. However, the ICG+ group had poorer changes compared with the ICG- group at 1 and 3 months (p = 0.038, p = 0.012, respectively). Central foveal thickness and ELM defect did not differ between the 2 groups at each period. The IS/OS defect in the ICG+ group was significantly greater at 1 and 3 months than that in the ICG- group (p = 0.026, p = 0.048, respectively).

CONCLUSIONS

ICG staining may affect the recovery process of macular morphology and visual acuity in the first several months after MH surgery.

Efficacy of autologous platelets in macular hole surgery

The introduction of optical coherence tomography has allowed accurate measurement of the size of macular holes. A retrospective consecutive review was performed of 21 patients undergoing macular hole repair with vitrectomy, gas tamponade, and autologous platelet injection and we assessed the effect of macular hole parameters on anatomic and functional outcomes. We looked at the demographic features, final visual outcome, and anatomical closure. Twenty-one patients were included in the study. They underwent routine vitrectomy with gas tamponade (C3F8) and injection of autologous platelets. All patients were advised to maintain a facedown posture for 2 weeks. Anatomical closure was confirmed in all cases and 20 out of 21 of patients had improved postoperative visual acuity by two or more lines. In our series, the macular hole dimensions did not have much effect on the final results. The use of autologous platelets and strict facedown posture seems to be the deciding factor in good anatomical and visual outcome irrespective of macular hole dimensions.

Brilliant Blue G as protective agent against trypan blue toxicity in human retinal pigment epithelial cells in vitro

BACKGROUND

Combinations of trypan blue (TB), Brilliant Blue G (BBG) and polyethyleneglycol had been shown before to be less toxic to ARPE retinal pigment epithelial cells than TB alone. We studied systematically the influence of combinations of dyes on cell damage.

METHODS

ARPE cells were exposed to TB (concentration range 0.025 to 1 %), BBG (0.0025 to 0.5 %), and combinations of the two dyes, dissolved in phosphate buffered saline (PBS), for periods between 5 and 60 min. Cell damage was monitored with the WST-1 assay. The effect of different salt concentration was measured in the same way.

RESULTS

TB in concentrations of 0.075 % and higher was toxic to the cells already after 30 min incubation. BBG was toxic after 30 min in concentration of 0.1 % and higher, but had a protective effect on cells with incubation time of 5 min and concentrations up to 0.1 %. BBG at concentrations of 0.025 % protected against TB-induced damage at 5 min and 30 min incubation. Salt concentrations between 113 and 225 mM did not influence cell survival even after 30 min. In the presence of TB, propidium iodide bound strongly to the cells.

CONCLUSIONS

BBG acts as a protecting agent against TB toxicity.

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

PURPOSE

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

DESIGN

Laboratory investigation.

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.