Surgical effects and complications of indocyanine green-assisted internal limiting membrane peeling for idiopathic macular hole

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.

The intraocular staining potential of anthocyanins and their retinal biocompatibility: a preclinical study

PURPOSE

To perform preclinical studies to determine the efficacy and safety of anthocyanins as stains for the internal limiting membrane (ILM) of the eye.

MATERIALS AND METHODS

Cyanidin (Cya), delphinidin (Del), luteolinidin (Lut), peonidin (Peo) and pelargonidin (Pel) were evaluated. These natural dyes were used to stain the lens capsule and ILM of pig eyes. The effects of these dyes on retinal cell viability was determined using a water-soluble tetrazolium salt assay, and oxidative stress was measured in vitro. Histopathology, in situ TUNEL labelling, transmission electronic microscopy (TEM), and electroretinography (ERG) were performed on rats following the intravitreal and subretinal injection of the neuroprotective dyes.

RESULTS

All anthocyanins stained the lens capsule and ILM of the pigs at a concentration of 1 mg/ml. Del, Lut and Peo were non-toxic and produced survival rates in the ARPE19 and RGC5 cells that were similar to those in control cells. We treated eyes with H₂O₂ and three dyes (Del, Lut, and Peo) to explore the possible neuroprotective effects and observed significantly higher survival rates in the ARPE19 cells treated with Del, Lut or Peo and the RGC5 cells treated with Lut or Peo than those in the control cells. Three dyes were intravitreally and subretinally injected into rats in vivo, and the histology showed mildly disorganized retinal cell layers. TUNEL staining and TEM examinations did not reveal additional toxic effects. Rat ERGs were not altered after intravitreal injections.

CONCLUSIONS

This preclinical study, Del, Lut, and Peo show potential as staining agents and warrant further investigation as vital dyes.

PARS PLANA VITRECTOMY AND WIDE INTERNAL LIMITING MEMBRANE PEELING WITH PERFLUOROPROPANE TAMPONADE FOR HIGHLY MYOPIC FOVEOSCHISIS-ASSOCIATED MACULAR HOLE

PURPOSE

To evaluate the outcomes of pars plana vitrectomy and wide internal limiting membrane peeling with perfluoropropane tamponade (C3F8) for highly myopic foveoschisis-associated macular hole.

METHODS

Prospective consecutive cases with highly myopic foveoschisis-associated macular hole were recruited. All the patients underwent pars plana vitrectomy and indocyanine green-aided internal limiting membrane peeling, the range of internal limiting membrane peeling was broadened beyond the vascular arcades and to the nasal side of the optic disc. With tamponade of 16% C3F8, all the patients kept a face-down position postoperatively. The main outcomes were best-corrected visual acuity and primary anatomical success rate.

RESULTS

There were 25 patients (25 eyes) included, with a mean age of 54.8 ± 7.2 years. The mean follow-up duration was 14.2 ± 3.9 months. The mean preoperative logarithm of the minimum angle of resolution best-corrected visual acuity (Snellen equivalent) was 1.489 ± 0.558 (20/617). The mean postoperative logarithm of the minimum angle of resolution best-corrected visual acuity at the final follow-up was 0.882 ± 0.522 (20/152), the difference being statistically significant with the preoperative one (P < 0.001). At the final follow-up, 17 eyes (68.0%) had vision improvement, and the primary anatomical success rate was 84.0% (21/25).

CONCLUSION

Pars plana vitrectomy and wide internal limiting membrane peeling with C3F8 tamponade is effective and safe to achieve a high anatomical success rate of highly myopic foveoschisis-associated macular hole closure and regain visual function.

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.

Idiopathic epiretinal membrane

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Anatomical and functional outcome in brilliant blue G assisted chromovitrectomy

PURPOSE

To evaluate the potential of brilliant blue G (BBG) for intraoperative staining of the inner limiting membrane (ILM) with respect to staining properties and surgical outcome.

METHODS

In a retrospective, non-comparative clinical case series, we analysed 17 consecutive chromovitrectomy interventions for surgery of macular holes, ERMs, vitreoretinal traction syndromes and cystoid macular oedema. Following complete posterior vitreous detachment, BBG was injected into the vitreous cavity at a concentration of 0.25 mg/ml, followed by immediate washout. Main outcome measures were staining properties, visual acuity, central visual field testing and optical coherence tomography (OCT) measurements over a mean follow-up period of 3 months.

RESULTS

ILM staining was somewhat less intensive for BBG than for average indocyanine green (ICG) chromovitrectomy. However, the ILM was removed successfully without additional ICG in 15/17 patients. Postoperative visual acuity was improved in 16/17 patients and remained unchanged in one patient. Central retinal OCT thickness showed a postoperative reduction, with values ranging from +7 to -295 microm (median -89 microm). Neither visual field defects nor any other adverse events were recorded.

CONCLUSION

BBG permits sufficient staining for safe ILM removal. In this short-term study, good anatomical and functional results were achieved and no adverse events were observed.

Involvement of illumination in indocyanine green toxicity after its washout in the ex vivo rat retina

PURPOSE

To elucidate the involvement of illumination in indocyanine green (ICG) retinal toxicity.

METHODS

We incubated isolated rat retinas with or without illumination after exposure to 0.5% ICG. We also examined whether a time lag following ICG exposure before illumination altered the damage. Toxicity was evaluated by histologic and biochemical assays, including measurement of lactate dehydrogenase release.

RESULTS

Retinas fixed immediately after ICG exposure showed minimal morphologic changes. However, illumination for 3 hours at 34 degrees C starting after washout of ICG selectively damaged the outer nuclear layer. Retinas incubated for 3 hours under the same condition in the dark showed preserved morphology but were damaged by subsequent illumination. When retinas were illuminated after washout of ICG at a lower temperature (30 degrees C), the damage was attenuated. Results obtained using lactate dehydrogenase release were consistent with these morphologic changes.

CONCLUSIONS

Incubating retinas in the dark and cooling after ICG exposure significantly inhibited retinal damage, suggesting that ICG interacts with illumination to induce retinal damage.

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.