Outcome of ICG-assisted ILM peel in macular hole surgery

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.

Surgical Management of Recurrent and Persistent Macular Holes: A Practical Approach

Primary surgery for macular hole (MH) closure has a high success rate with current methods of pars plana vitrectomy and internal limiting membrane (ILM) peeling. When primary surgery fails, there are several options available for secondary repair, including extension of the ILM peel, creation of an ILM flap, pedunculated ILM flap, lens capsule flap transplantation, autologous retinal transplantation, use of a human amniotic membrane plug, adjuvant autologous platelet concentrate, induction of macular detachments with subretinal blebs, and creation of retinal incisions. In this review, we discuss the practical approach to each of these surgical techniques for the management of recurrent or persistent MHs.

Efficacy of different doses of dye-assisted internal limiting membrane peeling in idiopathic macular hole: a systematic review and network meta-analysis

PURPOSE

Pars plana vitrectomy is the gold standard for the treatment of idiopathic macular hole. Several chromovitrectomy dyes have been used to improve the visualization of the internal limiting membrane (ILM), including indocyanine green, trypan blue (TB), brilliant blue G (BBG), and triamcinolone acetonide (TA). We conducted a network meta-analysis (NMA) to establish the optimum concentration of chromovitrectomy dye-assisted ILM peeling for IMH.

METHODS

We searched PubMed, Embase, and Cochrane Library for relevant studies before January 2020. We performed a random-effects NMA using STATA version 15.1 to assess mean difference and odds ratios with 95% confidence intervals.

RESULTS

We identified twelve retrospective trails and five randomized controlled trials (RCTs), comprising 1 492 patients of IMH on stage II-IV for ILM peeling. The results of IMH closure rate show that the effect of ILM peeling without dye was better than 0.25% ICG, the effects of ILM peeling with 0.5% ICG or TA were better than without dye, and the effects of ILM peeling with 0.05% BBG, 0.15% TB, 0.5% ICG or 0.05% ICG were better than 0.25% ICG. Ranking probability analysis shows that the rates of IMH closure after ILM peeling with 0.15% TB or 0.05% BBG were better than nine other concentrations of chromovitrectomy dyes.

CONCLUSION

The 0.15% TB and 0.05% BBG were recommended as the better efficient treatment-assisted ILM peeling for IMH closure. For retina specialists who prefer to use ICG to assist ILM peeling, 0.05% ICG may be a good choice. However, high-quality large-scale RCTs are recommended to confirm the NMA results.

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

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

Outcomes of 4 surgical adjuvants used for internal limiting membrane peeling in macular hole surgery: a systematic review and network Meta-analysis

AIM

To compare the outcomes of four adjuvants used for internal limiting membrane (ILM) peeling in macular hole surgery, including indocyanine green (ICG), brilliant blue G (BBG), triamcinolone (TA) and trypan blue (TB), through systematic review and random-effects Bayesian network Meta-analysis.

METHODS

PubMed, Cochrane library databases and Web of Science were searched until August 2018 for clinical trials comparing the above four adjuvants. ORs for postoperative best corrected visual acuity (BCVA) improvement and primary macular hole closure rates were compared between the different adjuvants.

RESULTS

Twenty-seven eligible articles were included. For postoperative BCVA improvement, results of BBG-assisted peeling were significantly more favorable than those of ICG (WMD 0.08, 95% credible interval 0.01-0.16) and TA ranked highest. No significant differences were found between any other two groups in postoperative BCVA improvement. For postoperative primary macular hole closure rates, BBG ranked highest. However, no significant differences were shown between any two groups.

CONCLUSION

TA and BBG are the optimum adjuvants for achieving postoperative BCVA improvement macular hole surgery with adjuvant-assisted ILM peeling. Among all adjuvants, the use of BBG is associated with the highest postoperative macular hole closure rate.

Internal limiting membrane peeling with different dyes in the surgery of idiopathic macular hole: a systematic review of literature and network Meta-analysis

AIM

To evaluate the effect of internal limiting membrane (ILM) peeling with indocyanine green (ICG), brilliant blue G (BBG), triamcinolone acetonide (TA), trypan blue (TB), or without dye for the treatment of idiopathic macular hole (IMH).

METHODS

A search was conducted using PubMed, EMBASE, and CENTRAL (Cochrane Central Register of Controlled Trials) for related studies published before October 2018.

RESULTS

A total of 29 studies and 2514 eyes were included in this network Meta-analysis. For IMH closure, the rank from the best to the worse treatment was: BBG, TB, TA, ICG, and no dye. There was a significant difference in postoperative IMH closure rate between BBG and no dye. The rank of the best to the worse treatment to improve visual acuity was: BBG, TB, no dye, TA, and ICG. The improvement rate of visual acuity after using BBG was significantly higher than ICG. The improvement rate of visual acuity was more favorable with TB than ICG, TA, and no dye.

CONCLUSION

BBG can contribute to better anatomical and functional outcomes compared to other dyes for ILM peeling in patients with IMH. The results show that the best treatment of ILM peeling with dyes is BBG.

Long-Term Outcomes after Macular Hole Surgery

PURPOSE

To evaluate the structural and visual outcomes after pars plana vitrectomy (PPV) for idiopathic full-thickness macular hole (MH) with at least 5 years of follow-up information.

DESIGN

Retrospective case series.

PARTICIPANTS

Patients with idiopathic MH who had at least 5 years of follow-up information after PPV.

METHODS

Best-corrected visual acuity (BCVA) was recorded preoperatively and, when available, at 1, 2, 3, 5, 8, and 10 years after surgery. Reestablishment of the postoperative integrity of the ellipsoid zone (EZ) and the external limiting membrane (ELM) and presence of cystoid spaces were evaluated using spectral-domain (SD) OCT.

MAIN OUTCOME MEASURES

Postoperative BCVA and its correlation with different SD OCT parameters.

RESULTS

Eighty-seven eyes of 80 patients with a mean age at surgery of 68.9±7.03 years were included. The mean postoperative follow-up was 9.6±4.3 years (median, 9 years; range, 5-22 years). The mean preoperative BCVA was 0.20±0.14 (range, 0.03-0.66). Postoperative BCVA was improved at all time points compared with preoperative BCVA (P < 0.05). Improvement in the postoperative BCVA remained stable 10 years after surgery. Initial successful closure of MH was achieved in 82 eyes (94%). Macular hole reopening occurred in 7 eyes (8.0%). Eleven eyes (13%) were reoperated: 4 eyes (4.5%) for persistence and 7 eyes (8.0%) for reopening of MH. Indocyanine green (ICG) stain was used in 22 eyes (25.2%). Among 57 patients (66%) who were phakic before surgery, 52 eyes (91.2%) underwent cataract extraction after PPV at a mean duration of 32.7±38.5 months (range, 2-187 months). Postoperative EZ integrity was restored in 52 eyes (60%), ELM integrity was restored in 54 eyes (62%), and cystoid spaces of variable severity were observed in 28 eyes (32%). Preoperative BCVA of 20/60 or better and postoperative reestablished ELM and EZ integrity were associated significantly with better postoperative BCVA at different postoperative follow-up visits (P < 0.05).

CONCLUSIONS

Visual acuity improvement after MH surgery continued during the first 3 years after PPV and was maintained thereafter in a substantial fraction of patients, and final BCVA correlated with better preoperative BCVA and better postoperative OCT parameters.

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.

Changes in visual field defects during 10-year follow-up for indocyanine green-assisted macular hole surgery

PURPOSE

To determine whether the visual field defects detected within 3 months of indocyanine green (ICG)-assisted inner-limiting membrane (ILM) peeling continue to worsen over longer periods.

METHODS

This was a retrospective observational case series. Four eyes with visual field defects that developed within 3 years of ICG-assisted ILM peeling for a macular hole (MH) were examined yearly for 10 years. The main outcome measures were the degree of mean deviation (MD) determined by Humphrey perimetry with the 30-2 SITA-Fast program and the best-corrected visual acuity (BCVA).

RESULTS

Four patients were examined yearly for more than 10 years, with a mean duration of follow-up of 139.5 months (11.6 years) and a range of follow-up of 137-156 months (11.4-13 years). The mean (±standard deviation) preoperative MD value was -4.99 ± 3.26 dB, and the mean postoperative MD values were -12.9 ± 1.29 dB after 1 year, -14.1 ± 0.75 dB after 3 years, and -12.73 ± 2.65 dB after 10 years. The mean preoperative BCVA was 0.65 ± 0.26 logarithm of the minimal angle of resolution (logMAR) units, and the postoperative BCVA was 0.21 ± 0.07 logMAR units at 1 year, 0.28 ± 0.21 logMAR units at 3 years, and 0.14 ± 0.06 dB logMAR units at 10 years.

CONCLUSIONS

The visual field defects detected soon after ICG-assisted ILM peeling continued to worsen for 3 years, but not thereafter.

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.

Complications of Macular Peeling

Macular peeling refers to the surgical technique for the removal of preretinal tissue or the internal limiting membrane (ILM) in the macula for several retinal disorders, ranging from epiretinal membranes (primary or secondary to diabetic retinopathy, retinal detachment…) to full-thickness macular holes, macular edema, foveal retinoschisis, and others. The technique has evolved in the last two decades, and the different instrumentations and adjuncts have progressively advanced turning into a safer, easier, and more useful tool for the vitreoretinal surgeon. Here, we describe the main milestones of macular peeling, drawing attention to its associated complications.

Vitrectomy for idiopathic macular hole

BACKGROUND

A macular hole is an anatomic opening in the retina that develops at the fovea. Macular holes can be seen in highly myopic eyes or following ocular trauma, but the great majority are idiopathic. Pars plana vitrectomy was introduced to treat full-thickness macular holes, which if left untreated have a poor prognosis since spontaneous closure and visual recovery are rare.Vitrectomy is a surgical technique involving the removal of the vitreous body that fills the eye. The surgeon inserts thin cannulas into the eyes through scleral incisions to relieve traction exerted by the vitreous or epiretinal membranes to the central retina and to induce glial tissue to bridge and close the hole.

OBJECTIVES

The primary objective of this review was to examine the effects of vitrectomy for idiopathic macular hole on visual acuity. A secondary objective was to investigate anatomic effects on hole closure and other dimensions of visual function, as well as to report on adverse effects recorded in included studies.

SEARCH METHODS

We searched the Cochrane Eyes and Vision Group Trials Register (4 March 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to March 2015), EMBASE (January 1980 to March 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to March 2015), the Web of Science Conference Proceedings Citation Index-Science (CPCI-S) (January 1980 to March 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 4 March 2015.

SELECTION CRITERIA

We included randomised controlled trials comparing vitrectomy (with or without internal limiting membrane peeling) to no treatment (that is observation) for macular holes.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently extracted the data. We estimated best corrected visual acuity and macular hole closure at 6 to 12 months of follow-up.

MAIN RESULTS

Three studies provided data on the comparison between vitrectomy and observation in eyes with macular hole and visual acuity less than 20/50. Two studies, conducted in the USA and published in 1996 and 1997, used a similar protocol and included participants with stage II macular hole (42 eyes randomised, 36 analysed, number of participants not reported) or participants with stage III/IV hole (129 eyes of 120 participants, 115 eyes in analyses). The third study, conducted in the UK and published in 2004, included 185 eyes of 174 participants with full-thickness macular hole (41 eyes with stage II holes and 74 eyes with stage III/IV holes in analyses). Studies were of good quality for randomisation and allocation concealment, whereas visual acuity measurement was unmasked.At 6 to 12 months, visual acuity was improved by about 1.5 Snellen lines (-0.16 logMAR, 95% confidence intervals -0.23 to -0.09 logMAR, 270 eyes, moderate-quality evidence). The chances of macular hole closure at 6 to 12 months were greatly increased using vitrectomy, yielding an odds ratio of 31.4 (95% confidence intervals 14.9 to 66.3, 265 eyes, high-quality evidence; raw sum data: 76% vitrectomy, 11% observation). Vitrectomy was beneficial both in smaller (stage II) and in larger (stage III/IV) macular holes.The largest study reported that cataract surgery was needed in about half of cases at two years after operation and that retinal detachment occurred in about 5% of operated eyes.

AUTHORS' CONCLUSIONS

Vitrectomy is effective in improving visual acuity, resulting in a moderate visual gain, and in achieving hole closure in people with macular hole. However, these results may not apply to modern surgery due to technological improvements in vitrectomy techniques.

Anatomical and Functional Outcomes of Pars Plana Vitrectomy for Lamellar Macular Defects

PURPOSE

The aim of this study is to investigate the anatomical and functional outcomes of surgical management of lamellar macular defects.

DESIGN

This study is a retrospective observational case series.

METHODS

Overall, the records of 89 eyes of 78 consecutive patients with a clinical diagnosis of either lamellar macular hole, macular pseudohole, or foveal pseudocyst were reviewed. Twenty-one (23.6%) of the 89 eyes underwent pars plana vitrectomy by a single ophthalmologist. Preoperative and postoperative visual acuities (VAs) were compared, and the anatomical outcome of vitrectomy was examined by studying the restoration of the foveal contour on optical coherence tomography (OCT) scans. Comparisons of visual acuity and OCT measurements between vitrectomized and nonvitrectomized eyes were made. Comparisons were also made between the 3 different types of lamellar macular defects.

RESULTS

Anatomical closure of the lamellar macular holes was achieved with a single surgical procedure in all vitrectomized eyes as confirmed by OCT. Visual acuity improved in 15 eyes (71%), from 0.39 ± 0.30 logMAR preoperatively to 0.26 ± 0.19 logMAR postoperatively (t20 = 2.425; P = 0.025). Macular pseudohole was associated with better presenting VA (F2,86 = 8.524; P < 0.001) and postoperative VA (F2,18 = 8.920; P = 0.002) than the other types of lamellar defects. Better postoperative VA was significantly correlated with better preoperative VA (r = 0.579; P = 0.006) and greater preoperative central foveal thickness (r = -0.535; P = 0.012).

CONCLUSIONS

Pars plana vitrectomy provided a high success rate of anatomical and functional improvement for eyes with all types of lamellar macular defects.

Temporal changes in foveal contour after macular hole surgery

BACKGROUND

To investigate the changes in inner foveal contour after surgery for macular hole (MH) and its clinical implications.

METHODS

This retrospective observational case series included 66 eyes from 66 patients who underwent surgery for MH. Notching of tissue was defined as an abrupt alteration in the inner contour of the parafoveal tissue based on postoperative optical coherence tomography (OCT) image. The distance between the parafoveal edges of the outer plexiform layer (OPL) was defined as the inter-OPL distance. The inter-OPL distance was divided into nasal, temporal, superior, and inferior lengths. The difference in the lengths of each direction between the early and late postoperative period was compared between directions with and without notching.

RESULTS

The early and late postoperative examination was performed at 4.6±2.9 weeks and 6.2±0.6 months, respectively. Notching of tissue was noted in 54 eyes (81.8%). In 53 eyes with a measurable inter-OPL distance, the notching of tissue was noted in 45 eyes (84.9%) regardless of preoperative MH size. The mean amount of foveal tissue elongation that occurred during the designated period was 104.6±68.8 and 78.4±72.9 μm in the directions with and without the notching of tissue (P<0.001), respectively.

CONCLUSIONS

The changes in the inner foveal contour, including notching of tissue and elongation of foveal tissue, were noted in the majority of eyes after MH surgery. Notching of tissue on OCT image could be a clinical marker for the development of foveal tissue elongation after MH surgery.

Retinal function assessment of trypan blue versus indocyanine green assisted internal limiting membrane peeling during macular hole surgery

OBJECTIVE

To compare multifocal electroretinography (mfERG) retinal function and the anatomical and visual outcomes of macular hole surgery performed with indocyanine green (ICG) or trypan blue (TB).

DESIGN

Prospective, randomized study.

PARTICIPANTS

Twenty-five eyes of 24 patients.

METHODS

Patients underwent a pars plana vitrectomy with removal of the internal limiting membrane. In 14 eyes, internal limiting membrane visualization during macular hole repair was performed using TB, and ICG was used in 11 eyes. The examination protocol (performed before surgery and at 3 weeks, 3 months, 6 months, and 12 months after surgery) included optical coherence tomography, mfERG (mfERG-103 hexagons), and assessment of best corrected visual acuity (BCVA) and contrast sensitivity (CS).

RESULTS

Closure of macular hole was achieved in 100% of the cases. In the TB group, P1 amplitude and implicit time improved significantly at 12 months after surgery (P < 0.05), whereas in the ICG group, significant improvement occurred at both 6 (P < 0.05) and 12 months (P < 0.01). BCVA improved significantly in both groups at 6 and 12 months (P < 0.01). Both groups also showed a statistically significant CS improvement at spatial frequency of 6 cycles per degree (P = 0.01) 1 year postoperatively. At 12 months, improvement of P1 amplitude and implicit time, BCVA, and CS was not different between groups.

CONCLUSIONS

In this study, the use of TB or ICG appears to yield similar improvement in terms of BCVA, CS, and mfERG amplitude and implicit time changes at 12 months.

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.

Techniques, rationale, and outcomes of internal limiting membrane peeling

BACKGROUND

The internal limiting membrane represents the structural interface between the retina and the vitreous and has been postulated to serve several essential functions. Recently, internal limiting membrane peeling has been used in the treatment of a variety of retinal disorders. We review the history, techniques, rationale, and outcomes of internal limiting membrane peeling.

METHODS

A review of the literature.

RESULTS

Internal limiting membrane peeling has been used to successfully treat a variety of retinal disorders including macular hole, epiretinal membrane, diabetic macular edema, retinal vein occlusion, and others.

CONCLUSION

Internal limiting membrane peeling may serve as an important component in the armamentarium of retinal surgery.

Unanticipated vision loss after pars plana vitrectomy

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

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.

In vivo toxicity testing of methyl blue and aniline blue as vital dyes for intraocular surgery

PURPOSE

To investigate the biocompatibility of methyl blue and aniline blue as vital dyes for vitreoretinal surgery in an in vivo rat model and to evaluate the effect of these dyes on retinal structure and function.

METHODS

Adult Brown-Norway rats received intravitreal injections of 0.1%, 0.2%, and 2% methyl blue or aniline blue dissolved in balanced salt solution with balanced salt solution serving as a control. Retinal toxicity was assessed 7 days thereafter by means of retinal ganglion cell counts, light microscopy, and electroretinography.

RESULTS

No significant decrease in retinal ganglion cell counts at concentrations up to 0.2% was observed. At 2%, however, a significant retinal ganglion cell loss was detected with both dyes (more pronounced for aniline blue). Light microscopy showed no structural changes in the central retina for concentrations up to 0.2%. Electroretinographies detected no adverse effects of methyl blue or aniline blue on rod- or cone-driven responses at concentrations up to 0.2%.

CONCLUSION

Methyl blue and aniline blue are very biocompatible and may, therefore, be usable for intraocular surgery. Further testing with other animal models will be necessary to confirm this. The safety margin of methyl blue is possibly higher than that of aniline blue.

Comparison of the in vitro safety of intraocular dyes using two retinal cell lines: a focus on brilliant blue G and indocyanine green

PURPOSE

To compare the in vitro toxicity of brilliant blue G (BBG), indocyanine green (ICG), Trypan blue (TB), and Evans blue (EB) in a human retinal pigment epithelial cell line (ARPE-19) and a murine retinal ganglion/Muller glial (RGC) primary cell culture.

DESIGN

In vitro cell biology experimental study.

METHODS

The dose-dependent toxicity of the dyes was determined by exposing each dye at four different concentrations to the two cell cultures for a short exposure (three minutes) and a medium exposure (30 minutes). The time-dependent toxicity of the dyes was also determined. All four dyes, each diluted to 1/500th of stock concentration, were applied only to the ARPE-19 cells for a prolonged exposure of two, 24, 48, and 72 hours. Cell viability was measured via a mitochondrial dehydrogenase assay.

RESULTS

BBG was the only dye to cause toxicity in the ARPE-19 cell line at short exposure times. BBG and TB demonstrated toxicity at medium exposure times. BBG and ICG demonstrated toxicity at long exposure times and dilute concentrations. At short exposure times, none of the dyes caused toxicity in the RGC mixed primary cultures. In contrast, at medium exposure times, all dyes except ICG demonstrated toxicity that lessened with lower concentrations.

CONCLUSIONS

All dyes demonstrated relatively safe viability profiles in both cell lines at surgically relevant concentrations and times. Cell toxicity could be elicited at higher concentrations and longer exposure times. ICG had a favorable viability profile at almost all of the concentrations and times tested.

Should Indocyanine green should be used to facilitate removal of the internal limiting membrane in macular hole surgery

Indocyanine green (ICG) is one of several vital dyes that are used in vitreoretinal surgery to aid visualization of diaphanous collagenous tissues in what has been called chromovitrectomy. As shown herein, much has been written about the use and rather narrow safety profile of ICG. The discussion surrounding its applications would have ended long ago were it not for the occasional patient who keeps returning to the office with permanent central scotomas after ICG-assisted macular hole surgery. The purpose of this Viewpoint is to reemphasize potential methods of proper use and clarify safety issues of this particular vital dye that enhances surgical technique but not necessarily visual outcome.

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

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Vitrectomy without postoperative posturing for idiopathic macular holes

PURPOSE

To determine the success of vitrectomy with ILM peeling and C(3)F(8) tamponade for macular holes without the need for postoperative face-down posturing.

METHODS

Twenty-four eyes of 24 consecutive patients undergoing pars plana vitrectomy with indocyanine green-assisted ILM peeling and C(3)F(8) tamponade without prone posturing were included in the study. All patients had follow up on 1 day, 2 weeks and 3 months postoperatively. Biomicroscopy and optical coherence tomography were used to assess macular hole closure at 3 months postoperatively. Snellen visual acuity was compared pre- and postoperatively.

RESULTS

Of the 24 eyes recruited, two (8%) had stage II, 17 (71%) had stage III and five (21%) had stage IV macular holes. Nineteen (79%) eyes were phakic and five (21%) eyes were pseudophakic at the time of surgery. The macular holes had been present for an average of 7.5 months (range 3-18 months). At 3-month follow up, 22/24 (91.6%) holes were closed. Both of the two holes that failed to close were stage IV macular holes. Preoperative visual acuity ranged from 6/18 to 6/60 (mean 6/36). Postoperative visual acuity ranged from 6/9 to 6/60 (mean 6/18). Eighteen eyes had improvement of visual acuity of at least one line on the Snellen chart, six eyes had no improvement. No eyes had worse vision postoperatively.

CONCLUSION

Macular hole surgery without face-down posturing provides anatomical and functional results comparable to those with prone posturing. Combined phacovitrectomy is not essential to avoid prone posturing.

Vital dyes for chromovitrectomy

PURPOSE OF REVIEW

The aim of this article is to present the current state-of-the-art in regard to the application of vital dyes during vitreoretinal surgery, 'chromovitrectomy', as well as to overview the current literature regarding the properties of dyes, techniques of application, indications, and complications in chromovitrectomy.

RECENT FINDINGS

A large body of published research has recently addressed the toxicity profile of indocyanine green for chromovitrectomy. Experimental data demonstrate dose-dependent toxicity of indocyanine green to various retinal cells. Newer generation vital dyes for chromovitrectomy include trypan blue, patent blue, triamcinolone acetonide, infracyanine green, sodium fluorescein, bromophenol blue, fluorometholone acetate and brilliant blue. Novel instruments may enable a selective painting of preretinal tissues during chromovitrectomy.

SUMMARY

This review suggests that the field of chromovitrectomy represents an expanding area of research. The first line agents for internal limiting membrane staining in chromovitrectomy are indocyanine green, infracyanine green, and brilliant blue. Patent blue, bromophenol blue and trypan blue arose as outstanding biostains for visualization of epiretinal membranes. Novel dyes available for chromovitrectomy deserve further investigation.

Pathogenesis of macular hole recurrence and its prevention by internal limiting membrane peeling

PURPOSE

To determine the pathogenesis of macular hole recurrence after vitreous surgery and to evaluate internal limiting membrane (ILM) peeling to prevent recurrence.

METHODS

We conducted a retrospective, nonrandomized, comparative trial in which we performed pars plana vitrectomy with intravitreal gas injection on 161 consecutive eyes with macular holes without ILM peeling between September 1993 and June 1996 and on 150 consecutive eyes with ILM peeling between July 1999 and January 2003. Closure and reopening rates with and without ILM peeling were compared, and the evolution of recurrence was evaluated.

RESULTS

The macular holes closed in 85% of eyes without ILM peeling and in 94% of eyes with ILM peeling during the initial surgery. During mean follow-ups of 25 months and 30 months with and without ILM peeling, respectively, macular holes reopened in 6 eyes (4%) without ILM peeling; the macular holes did not reopen in any eye in which the ILM was peeled. Reopening first occurred 6 months to 48 months after the initial surgery and was associated with an epiretinal membrane (ERM) around the macular hole. The macular holes in four eyes closed permanently after repeated removal of a perifoveal ERM. The holes in the remaining two eyes closed permanently after ILM peeling after reopening occurred six and three times.

CONCLUSIONS

Macular holes reopen because of tangential contraction of the ERM postoperatively. ILM peeling prevents macular hole reopening by inhibiting recurrence of the ERM.

Comparison of in vitro toxicity of single vs double exposures of indocyanine green in human retinal pigment epithelial cell cultures

PURPOSE

To compare the in vitro effect of a single brief indocyanine green (ICG) exposure with a double exposure on retinal pigment epithelial (RPE) cells.

DESIGN

In vitro laboratory experimental study.

METHODS

Human ARPE-19 cells were exposed to a single dilute ICG exposure (0.5 mg/ml) or to two sequential exposures of identical volume and concentration. Viability was measured with a mitochondrial dehydrogenase assay and compared with nonexposed control cells.

RESULTS

Cell viability was not statistically different between the single-exposed, double-exposed, or control cell populations.

CONCLUSIONS

When used intraoperatively to stain the internal limiting membrane, dilute ICG dye sometimes does not adequately enhance visualization of the internal limiting membrane. Occasionally, it is necessary to repeat the dye exposure to achieve the desired visibility. In this study, RPE cells subjected to two consecutive short exposures of ICG showed no marked difference in cell survival when compared with cells exposed to a single application of ICG and to control cells.

LONG-TERM OUTCOMES OF INTERNAL LIMITING MEMBRANE PEELING WITH AND WITHOUT INDOCYANINE GREEN IN MACULAR HOLE SURGERY

PURPOSE

To compare the long-term anatomic closure rate and visual outcome in patients who underwent internal limiting membrane (ILM) peeling with and without indocyanine green (ICG) dye staining for idiopathic macular hole repair.

DESIGN

Retrospective, nonrandomized, comparative study of consecutive case series.

METHODS

A total of 190 eyes of 182 patients with idiopathic macular holes underwent macular hole repair between March 1998 and June 2003. Surgery consisted of pars plana vitrectomy, lensectomy if phakic, ILM peeling, intravitreal gas tamponade, and 1 week's face-down positioning. In the initial 94 consecutive eyes, ILM peeling was performed without adjuvants (non-ICG group). The subsequent 96 eyes underwent surgery with ICG-stained ILM peeling (ICG group), in which the ILM was stained with intravitreal application of 0.1 to 0.2 mL of 0.1% ICG solution.

RESULTS

Two groups of patients had comparable clinical backgrounds preoperatively. Mean follow-up time was 30.7 months in non-ICG group and 26.2 months in ICG group. Anatomic closure of the macular hole was achieved in 99% of the cases in both groups, with both groups showing statistically significant visual improvement. There was no statistically significant difference in visual acuity between the two groups at each follow-up visit. There were also no intraoperative or postoperative complications attributed to the use of ICG.

CONCLUSIONS

Long-term follow-up of patients undergoing ILM peeling for idiopathic macular hole repair shows equivalent anatomic and visual outcomes with and without the use of ICG.

Serial autofluorescence imaging over two years following indocyanine green-assisted internal limiting membrane peel for macular hole

A 65-year-old patient with an idiopathic full-thickness macular hole underwent a vitrectomy, inner limiting membrane (ILM) peel and gas tamponade. The ILM was stained using 0.5% indocyanine green (ICG). Postoperative autofluorescence imaging shows a central focal hyperfluorescence surrounded by a perifoveal hypofluoresecnt area corresponding to the dyed and peeled ILM. Serial autofluorescence images showed progressive decrease in staining until 2 years later when no signs of ICG autofluorescence were apparent. The visual acuity for this patient improved two Snellen lines from 6/36 to 6/18 at 2 years. ICG may not be clinically toxic as is currently feared.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Makulaforamen

The theory of macular hole pathogenesis, which had so far been based on biomicroscopy, has been considerably altered by optical coherence tomography. The precise presentation of vitreofoveal pathology shows that forces acting in different directions are associated with different stages of the disease, making surgical treatment adapted to the different stages possible. Some surgical procedures are still controversial, and there is still no gold standard in macular hole surgery. Especially no agreement exists on the benefit of internal limiting membrane peeling, possibly assisted by staining with indocyanine green. Also details of endotamponade and postoperative positioning are controversial. Therefore, the method of surgical treatment depends a lot on the individual surgeon. This review summarizes the broad spectrum of the literature and the present knowledge in this field.