Dissociated optic nerve fiber layer appearance after internal limiting membrane peeling for idiopathic macular hole

Perifoveal Microvascular Changes following Internal Limiting Membrane Peeling Surgery for Epiretinal Membrane and Macular Hole

INTRODUCTION

The aim of the study was to evaluate perifoveal microvasculature changes following pars plana vitrectomy with internal limiting membrane peeling for the epiretinal membrane (ERM) and macular hole (MH).

METHODS

This retrospective study included 59 eyes from 59 patients. Subjects were divided into two groups: an ERM group (n = 43) and an MH group (n = 16) based on the initial diagnosis. Swept-source optical coherence tomography angiography (SS-OCTA) was performed in the macular area, pre- and postoperatively. Perifoveal microvascular changes were calculated using MATLAB from the 6 × 6 mm SS-OCTA images, excluding the foveal avascular zone. Pre- and postoperative perifoveal vessel densities (pfVDs) were separately analyzed in six sectors (superior, superotemporal, inferotemporal, inferior, inferonasal, and superonasal) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). The baseline characteristics and other clinical factors were compared between the ERM and MH groups.

RESULTS

The postoperative best-corrected visual acuity significantly improved in both groups (p < 0.05). One year after surgery, the pfVD in the SCP of the ERM group significantly decreased in the inferotemporal sector (p = 0.049). The postoperative pfVD in the DCP of the MH group significantly decreased in temporal sectors (p < 0.05). The postoperative mean pfVD in the SCP in the MH group was significantly lower than that in the ERM group (p = 0.003). The presence of a dissociated optic nerve fiber layer (DONFL) was 75% in the MH group and 22% in the ERM group (p = 0.018). The correlation between the pfVD and DONFL was not statistically significant.

CONCLUSION

Postoperative pfVD reduction in the temporal sector, a corresponding area in which DONFL is present after MH surgery, was significantly observed. After vitreoretinal surgery in MH patients, OCTA may serve as a useful tool for monitoring perifoveal microvascular changes, especially in temporal sectors.

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.

Spotlight on the Internal Limiting Membrane Technique for Macular Holes: Current Perspectives

Pars plana vitrectomy has become the standard procedure for primary macular holes (MHs) repair, including the removal of the posterior cortical vitreous, the stripping of eventual epiretinal membranes, and finally an intraocular gas tamponade. During this procedure, peeling the internal limiting membrane (ILM) has been proven to increase closure rates and avoid postoperative reopening in several researches. In fact, even in large MHs more than 400 µm, the advantage of peeling off the ILM was highlighted by better anatomical closure rates. Nevertheless, some authors suggested that ILM peeling is not always essential, because it generates various side effects in retinal structure and function. Furthermore, the ideal amount of ILM peeling and the most effective strategies for removing the ILM are still subject of research. Different surgical modifications have been reported as alternatives to traditional peeling in certain clinical settings, including ILM flaps, ILM scraping, and foveal sparing ILM peeling. As regards large MHs, the introduction of ILM inverted flap appeared as a game changer, offering a significantly higher >90% closure rate when compared to traditional ILM peeling. Modifications to inverted ILM flap procedures have been claimed in recent years, in order to define the best area and direction of ILM peeling and its correlation with functional outcomes. Moreover, several innovations saw the light in the setting of recurrent MHs, such as ILM free flap transposition, inverted ILM flap combined autologous blood clot technique, neurosensory retinal flap, and human amniotic membrane (HAM) plug, claiming higher anatomical success rate also in those complex settings. In conclusion, the aim of this review is to report how the success rate of contemporary macular surgery has grown since the turn of the century, especially for big and chronic MHs, analyzing in which way ILM management became a crucial point of this kind of surgery.

[Long-term functional and anatomical effects after macular hole surgery with internal limiting membrane peeling]

INTRODUCTION

To study the functional and anatomical effects of internal limiting membrane (ILM) peeling in macular hole surgery with a minimum follow-up of 10 years.

METHODS

Retrospective study of patients who underwent successful macular hole surgery prior to 2010. All patients underwent vitrectomy and ILM peeling after staining. Functional assessment included measurement of visual acuity and retinal sensitivity using microperimetry (NIDEK MP-3) as well as a subjective visual function questionnaire. Anatomical assessment was based on evaluation of the macular region and optic nerve using spectral domain optical coherence tomography (SD-OCT) with comparison to the fellow eye.

RESULTS

Fourteen women and five men were included. Visual acuity of operated eyes (0.07±0.08logMar) was not significantly different from that of fellow eyes (0.04±0.08logMar) (P=0.10). The mean retinal sensitivity of the operated eyes was 25.1±1.9dB with no difference from the fellow eyes 25.2±1.6dB (P=0.82). However, 2 patients exhibited 2 relative scotomas >10dB. On questioning, 3/19 patients (16%) described a disturbing scotoma in monocular vision, while 11/19 (58%) described metamorphopsia, and 3 subjectively assessed their visual loss at more than 60%. The external limiting membrane was present and intact in all patients, and the ellipsoid zone was restored in 16/19 patients (84%). The cone interdigitation zone was intact in 9 patients, altered in one patient and not interpretable in 9 patients. Retinal optic nerve fiber layer thickness showed a moderate loss of fibers in the operated group 95.9±9.5 versus 101.5±10.9 (P=0.001) in the fellow eyes. The ganglionic complex thickness in the operated eyes (90.1±8.3) was not significantly different from that of fellow eyes (91.9±8.8) (P=0.37).

CONCLUSION

ILM peeling in macular hole surgery induces anatomical changes in the inner layers of the retina, still visible on SD-OCT 10 years after the procedure. However, this remodeling of the inner layers does not appear to have significant deleterious effects on patients' retinal sensitivity or vision.

Involvement of Anoikis in Dissociated Optic Nerve Fiber Layer Appearance

Dissociated optic nerve fiber layer (DONFL) appearance is characterized by dimpling of the fundus when observed after vitrectomy with the internal limiting membrane (ILM) peeling in macular diseases. However, the cause of DONFL remains largely unknown. Optical coherence tomography (OCT) findings have indicated that the nerve fiber layer (NFL) and ganglion cells are likely to have been damaged in patients with DONFL appearance. Since DONFL appearance occurs at a certain postoperative period, it is unlikely to be retinal damage directly caused by ILM peeling because apoptosis occurs at a certain period after tissue damage and/or injury. However, it may be due to ILM peeling-induced apoptosis in the retinal tissue. Anoikis is a type of apoptosis that occurs in anchorage-dependent cells upon detachment of those cells from the surrounding extracellular matrix (i.e., the loss of cell anchorage). The anoikis-related proteins βA3/A1 crystallin and E-cadherin are reportedly expressed in retinal ganglion cells. Thus, we theorize that one possible cause of DONFL appearance is ILM peeling-induced anoikis in retinal ganglion cells.

Evaluation of Ganglion Cell-Inner Plexiform Layer Thickness after Vitreoretinal Surgery with Internal Limiting Membrane Peeling in Cases with Idiopathic Macular Hole

OBJECTIVES

To evaluate macular retinal ganglion cell-inner plexiform layer (GCIPL) thickness after vitrectomy with internal limiting membrane (ILM) peeling for idiopathic macular holes using spectral domain optical coherence tomography (SD-OCT).

MATERIALS AND METHODS

Eighteen eyes of 18 patients with unilateral idiopathic macular hole who underwent vitrectomy with ILM peeling were retrospectively analyzed. Healthy fellow eyes of the patients and 18 eyes of 18 age-matched healthy individuals constituted the control group. The patients were evaluated at 1 day, 1 week, 1 month, and 3 months after surgery. The best corrected visual acuity (BCVA) measurements, biomicroscopic examination findings and SD-OCT measurements were recorded. Ganglion cell-inner plexiform layer thickness was evaluated with ganglion cell analysis software of Cirrus HD-OCT before surgery and at 1 month and 3 months after surgery and compared with control groups. Presence of dissociated optic nerve fiber layer (DONFL) was evaluated with C-scan mode.

RESULTS

Of the 18 patients, 9 were male and 9 were female with a mean age of 65.6±5.6 (55-77) years. Preoperative BCVA was 0.75±0.19 logMAR, while it was 0.44±0.17 logMAR and 0.36±0.15 logMAR at postoperative 1 and 3 months, respectively (p<0.001). Postoperative mean GCIPL thickness was 66.33±17.28 µm. There was a correlation between mean GCIPL thickness and BCVA at postoperative 3 months (p<0.01). When compared with the control group, GCIPL thickness was significantly thinner in all quadrants of all patients at postoperative 3 months. Dissociated optic nerve fiber layer appearance was observed on C-scan in 13 of 18 eyes postoperatively. There was no correlation between the presence of DONFL and BCVA (p>0.05).

CONCLUSION

Internal limiting membrane peeling during macular hole surgery may cause functional and/or structural changes that may be associated with visual acuity. Significant GCIPL thinning and DONLF appearance may occur postoperatively.

The relationship between a dissociated optic nerve fibre layer appearance after macular hole surgery and Muller cell debris on peeled internal limiting membrane

PURPOSE

A dissociated optic nerve fibre layer (DONFL) is a characteristic change noted in inner retinal morphology after internal limiting membrane (ILM) peeling. It is thought to be due to trauma to Muller cells as the ILM is peeled from their attached end plates. In this study, we aimed to determine the extent and size of Muller cell debris on the retinal side of excised ILM and assess whether this correlated with the extent of DONFL observed postoperatively.

METHOD

Prospective single centre study of a consecutive series of patients undergoing macular hole surgery. Transmission electron microscopy of the ILM was used to assess Muller cell debris and postoperative spectral domain optical coherence tomography (SD-OCT) to assess the extent of DONFL. A variety of other pre- and postoperative features was also included.

RESULTS

Thirty-nine patients were analysed. There were retinal dimples characteristic of DONFL detected on SD-OCT in all 39 eyes. The portion of the retinal side of the ILM specimen covered by cellular debris ranged from 12% to 49%, with a median of 28%. Using linear regression, the percentage of retinal debris, the size of the debris and the postoperative visual acuity were significantly positively associated with the DONFL score. The total R squared for the model was 63.9%.

CONCLUSION

The extent of DONFL observed postoperatively can be partly explained by the amount of retinal side cellular debris on the retinal side of the peeled ILM. Surgical strategies which minimize this material could reduce the extent of DONFL.

ASSESSMENT OF THE SIGNIFICANCE OF CYSTIC CHANGES AFTER EPIRETINAL MEMBRANE SURGERY WITH INTERNAL LIMITING MEMBRANE REMOVAL

PURPOSE

To assess the prevalence and significance of cystic changes after internal limiting membrane peeling during epiretinal membrane surgery.

METHODS

A retrospective review was performed on 64 patients who underwent pars plana vitrectomy with membranectomy for idiopathic epiretinal membrane between January 2010 and January 2012 by a single physician. Pars plana vitrectomy alone (Group 1, n = 32) or in combination with phacoemulsification (Group 2, n = 32) was performed. Peeling of the epiretinal membrane was assisted by triamcinolone, and internal limiting membrane was peeled up to the vascular arcades with the aid of brilliant blue dye.

RESULTS

In Group 1, best-corrected visual acuity in logMAR (Snellen) improved from 0.53 ± 0.29 (20/68) at baseline to 0.23 ± 0.22 (20/34) at 6-month follow-up (P < 0.001). Two cases (6.3%) developed new cystic changes within the inner nuclear layer; however, there was no significant difference in best-corrected visual acuity at 6 months (P = 0.475). In Group 2, best-corrected visual acuity improved from 0.41 ± 0.17 (20/51) at baseline to 0.18 ± 0.15 (20/30) at 6 months (P < 0.001). Eight cases (25%) developed new inner nuclear layer cystic changes; however, there was no significant difference in best-corrected visual acuity at 6 months (P = 0.894).

CONCLUSION

Development of new inner nuclear layer cystic changes after epiretinal membrane surgery may be a frequent finding, but in contrast to cystoid macular edema, it does not seem to affect visual recovery and should be observed. The combination of pars plana vitrectomy with cataract extraction may increase the risk of inner nuclear layer cystic changes.

Optimal management of idiopathic macular holes

This review evaluates the current surgical options for the management of idiopathic macular holes (IMHs), including vitrectomy, ocriplasmin (OCP), and expansile gas use, and discusses key background information to inform the choice of treatment. An evidence-based approach to selecting the best treatment option for the individual patient based on IMH characteristics and patient-specific factors is suggested. For holes without vitreomacular attachment (VMA), vitrectomy is the only option with three key surgical variables: whether to peel the inner limiting membrane (ILM), the type of tamponade agent to be used, and the requirement for postoperative face-down posturing. There is a general consensus that ILM peeling improves primary anatomical hole closure rate; however, in small holes (<250 µm), it is uncertain whether peeling is always required. It has been increasingly recognized that long-acting gas and face-down positioning are not always necessary in patients with small- and medium-sized holes, but large (>400 µm) and chronic holes (>1-year history) are usually treated with long-acting gas and posturing. Several studies on posturing and gas choice were carried out in combination with ILM peeling, which may also influence the gas and posturing requirement. Combined phacovitrectomy appears to offer more rapid visual recovery without affecting the long-term outcomes of vitrectomy for IMH. OCP is licensed for use in patients with small- or medium-sized holes and VMA. A greater success rate in using OCP has been reported in smaller holes, but further predictive factors for its success are needed to refine its use. It is important to counsel patients realistically regarding the rates of success with intravitreal OCP and its potential complications. Expansile gas can be considered as a further option in small holes with VMA; however, larger studies are required to provide guidance on its use.

Regional reduction of ganglion cell complex after vitrectomy with internal limiting membrane peeling for idiopathic macular hole

Purpose. To determine whether the reduction of ganglion cell complex (GCC) thickness is uniform in the parafoveal region after vitrectomy with internal limiting membrane (ILM) peeling for idiopathic macular hole (MH). Methods. Thirty-nine consecutive eyes were studied. Vitrectomy was performed with ILM peeling with brilliant blue G (BBG) staining, and room air was used for an intraocular tamponade. The GCC thickness and retinal sensitivity were measured at the superior, inferior, nasal, and temporal quadrants around the fovea using spectral domain-optical coherence tomography (SD-OCT) and microperimetry (MP-1). The measurements were made at baseline, and at 3 and 6 months postoperatively. Results. In 38 of the 39 eyes, the MH was closed after the initial surgery. At three and six months, the percentage of eyes with significantly thinner GCC areas was higher at the temporal quadrant (40.5% at 3 months and 46.0% at 6 months) than that at the other quadrants (P < 0.001, P < 0.001, resp.). The retinal sensitivity was also significantly lower in the temporal area than in the other areas (15.7 dB at 3 months, P = 0.003; 15.4 dB at 6 months, P = 0.006). Conclusion. These findings indicate that the inner retina in the temporal area may be more vulnerable to surgical manipulations than the other areas.

ILM peeling technique influences the degree of a dissociated optic nerve fibre layer appearance after macular hole surgery

PURPOSE

We sought to assess the effect of two different internal limiting membrane [ILM] peeling techniques carried out during surgery for idiopathic macular holes on the postoperative extent of a dissociated optic nerve fibre layer appearance [DONFL].

METHODS

We collected prospective data of surgical records, videos, and pre- and postoperative imaging of a consecutive series of patients undergoing surgery for idiopathic macular hole with one of two surgeons. One surgeon used a forceps pinch-peel technique to peel the ILM, whereas the other surgeon used a diamond dusted membrane scraper. The extent of any DONFL was measured using spectral domain optical coherence tomography and blue reflectance imaging at three months postoperatively. A proportion of the ILMs removed were examined with transmission electron microscopy.

RESULTS

Fifty-seven patients were studied, with 41 in the forceps group and 16 in the scraper group. The groups were well matched, with no significant difference in any preoperative parameters. Some degree of DONFL was observed on the 3-month blue reflectance images in 88 % of the forceps group and 100 % of the scraper group [p = 0.14]. There was a significant difference in the total number of depressions in the nerve fibre layer typical of DONFL on OCT between the two groups [p = 0.001], and general regression analysis showed that the peeling technique used had the only significant association with the degree of DONFL observed. Electron microscopy showed large patches of cellular debris on the retinal side of the peeled ILM in 3 out of 4 cases in the scraper group and 1 out of 12 cases in the forceps group.

CONCLUSION

ILM peeling technique and possibly other surgeon-specific factors appear to influence the extent of DONFL observed after ILM peeling macular hole surgery.

Idiopathic vitreomacular traction and macular hole: a comprehensive review of pathophysiology, diagnosis, and treatment

Posterior vitreous detachment (PVD) is a common phenomenon in the aging eye. However, this may be complicated by persistent symptomatic vitreomacular adhesions that exert tractional forces on the macula (vitreomacular traction; VMT). VMT itself may be associated with epiretinal membrane formation and the development of idiopathic macular holes (IMH). Such pathologies may cause visual disturbances, including metamorphopsia, photopsia, blurred vision, and decreased visual acuity, which impact an individual's quality of life. Technologies such as optical coherence tomography allow an increasingly more accurate visualisation of the macular anatomy, including quantification of macular hole characteristics, and this facilitates treatment decision-making. Pars plana vitrectomy remains the primary treatment option for many patients with VMT or IMH; for the latter, peeling of the inner limiting membrane (ILM) of the retina has shown improved outcomes when compared with no ILM peeling. The development of narrow-gauge transconjunctival vitrectomy systems has improved the rate of visual recovery following surgery. Ocriplasmin, by degrading laminin and fibronectin at the vitreoretinal interface, may allow induction of PVD in a non-invasive manner. Indeed, clinical studies have supported its use as an alternative to surgery in certain patient populations. However, further research is still needed with respect to greater understanding of the pathophysiology underlying the development of VMT and IMH.

Retinal surface en face optical coherence tomography: a new imaging approach in epiretinal membrane surgery

PURPOSE

To describe the clinical effectiveness of a new imaging approach: en face spectral domain optical coherence tomography of the retinal surface before and after epiretinal membrane (ERM) and internal limiting membrane peeling.

METHODS

Retrospective analysis of preoperative and postoperative en face spectral domain optical coherence tomography images of the inner face of the macula obtained from 20 eyes of 20 patients undergoing vitrectomy with internal limiting membrane peeling for ERM.

RESULTS

Preoperatively, en face spectral domain optical coherence tomography imaging of the retinal surface clearly showed plaques surrounded by radiating folds because of ERM. It could also disclose areas possibly devoid of internal limiting membrane secondary to ERM contraction. A rough retinal surface was visible in the peeled area during the first postoperative month. At 3 months, various amounts of dimples were progressively observed in 13 of 15 eyes (87%). In all these cases, they lasted or increased in size and number at the last follow-up examination. Some residual epiretinal tissue was also detected by this technique.

CONCLUSION

En face spectral domain optical coherence tomography of the retinal surface is an interesting complement to standard retinal optical coherence tomography section that provides an easy-to-understand global overview of the retinal surface. It can detect and classify tiny progressive morphologic changes in the texture of the retinal surface occurring after internal limiting membrane peeling.

Swelling of the arcuate nerve fiber layer after internal limiting membrane peeling

PURPOSE

The purpose of the study is to report the incidence of changes of the retinal nerve fiber layer in the early postoperative period after internal limiting membrane peeling for idiopathic macular hole and epiretinal membrane surgery.

METHODS

Interventional, noncomparative retrospective case series. Fifty-six eyes of 55 patients with an epiretinal membrane and 33 eyes of 31 patients with macular hole underwent pars plana vitrectomy and internal limiting membrane peeling. All patients received a complete ophthalmic examination, infrared and autofluorescence photography, and spectral-domain optical coherence tomography preoperatively and also at approximately 1 week, 1 month, and 3 months postoperatively. Vitrectomy and gas tamponade were performed with internal limiting membrane peeling after staining with Brilliant Peel. The main outcome measures were the presence of postoperative swelling of the arcuate retinal nerve fiber layer on spectral-domain optical coherence tomography, infrared and autofluorescence photographs, and its effect on best-corrected visual acuity.

RESULTS

On infrared and autofluorescence photographs, 28 (31.46%) of 89 eyes with internal limiting membrane peeling exhibited swelling of the arcuate retinal nerve fiber layer 1 week to 1 month postoperatively. Swelling of the arcuate retinal nerve fiber layer increased during the first month after surgery and resolved after a mean period of 2 months. These features were best visualized by autofluorescence imaging, as three to five dark striae originating from the optic nerve head, radiating in an arcuate pattern toward the macula. Simultaneous spectral-domain optical coherence tomography scanning through the striae indicated that they correspond to areas of focal swelling of the arcuate nerve fiber layer. No significant differences were found in eyes with or without swelling of the arcuate retinal nerve fiber layer for mean age or pre- and postoperative best-corrected visual acuity (P > 0.05).

CONCLUSION

Swelling of the arcuate retinal nerve fiber layer often occurs after internal limiting membrane peeling for macular hole and epiretinal membrane. It is a transient feature after surgery that does not affect visual recovery. It is best visualized using infrared and autofluorescence imaging. Simultaneous infrared and spectral-domain optical coherence tomography imaging after macular surgery can detect transient inner retinal changes, which are not visible on clinical examination.

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.

Intraoperative use of handheld spectral domain optical coherence tomography imaging in macular surgery

PURPOSE

To describe the intraoperative use of handheld spectral domain optical coherence tomography (SDOCT) imaging in macular surgery.

DESIGN

Prospective, observational case series.

METHODS

A handheld SDOCT device was used to obtain preincision optical coherence tomography imaging in patients undergoing vitrectomy for macular diseases. After removal of the internal limiting membrane or the epiretinal membrane, repeat intraoperative imaging was obtained. Spectral domain optical coherence tomography findings were characterized.

RESULTS

An efficient technique was established for obtaining intraoperative SDOCT imaging. A total of eight patients were included in the study. Four patients underwent surgery for macular hole, three patients for epiretinal membrane, and one for vitreomacular traction. Comparison of the preincision and intraoperative SDOCT images demonstrated distinct changes in retinal contour and macular hole configuration. Intraoperative SDOCT imaging identified additional membranes in two patients.

CONCLUSION

The intraoperative use of handheld SDOCT imaging provides an efficient method for visualizing macular pathology. This technology may, in certain cases, help confirm or identify diseases that may be difficult to visualize during surgery.

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.

Internal Limiting Membrane Removal during Macular Hole Surgery

PURPOSE

To evaluate the effect of internal limiting membrane (ILM) peeling and other variables in hole closure and functional success rate after idiopathic macular hole surgery.

DESIGN

Retrospective, multicenter, observational study.

METHODS

The records of 1627 patients operated on for idiopathic macular hole were collected retrospectively from 28 surgeons. All patients underwent a single pars plana vitrectomy and were divided into 2 groups: with and without ILM peeling. Preoperative, intraoperative, and postoperative variables were evaluated.

RESULTS

The overall rate of macular hole closure was 94.1% in the ILM peeling group and 89.0% in the no ILM peeling group (P<0.001). The probability of achieving hole closure after surgery is 2.59 times higher if the ILM is peeled (95% confidence interval [CI], 1.71-3.92; P<0.001), 3.12 times higher for holes lasting less than 6 months (95% CI, 1.70-5.71; P<0.001), 4.94 (95% CI, 2.39-10.20) for stage 2 holes, and 2.34 (95% CI, 1.55-3.53) for stage 3 holes than that of patients with a stage 4 hole (P<0.001).

CONCLUSIONS

Internal limiting membrane peeling seems to improve hole closure for stage 3 and 4 holes and for long-lasting holes. Higher-stage macular holes and longer duration of symptoms are risk factors for surgical failure. In patients obtaining hole closure, there is no difference in functional results between pseudophakic peeled and not peeled patients, whereas in phakic patients, a better functional result in not peeled patients was seen.

Relationship between macular hole size and the potential benefit of internal limiting membrane peeling

AIM

To investigate the relationship between the size of macular holes and the possible benefit of internal limiting membrane (ILM) peeling.

METHODS

84 consecutive cases of idiopathic macular hole followed up for at least 3 months were included in this retrospective study. Surgery comprised pars plana vitrectomy, peeling of any epiretinal membrane, 17% C2F6 (hexafluoroethane) gas filling and 10 days of positioning. 36 eyes had ILM peeling. The main outcome measure was the macular hole closure rate checked by optical coherence tomography.

RESULTS

The overall postoperative closure rate was 90.5%. For macular holes > or =400 microm in diameter, the rate was 100% with ILM peeling versus 73.3% without (p = 0.015). For smaller macular holes, the rates were 100% in both groups. Postoperative gain in visual acuity was not significantly different in eyes with ILM peeling and those without.

CONCLUSIONS

ILM peeling does not seem to be useful for macular hole <400 mum in diameter. Its likely benefit has to be investigated for larger macular hole sizes, for which the failure rate is higher.

Relationship of dissociated optic nerve fiber layer appearance to internal limiting membrane peeling

PURPOSE

The dissociated optic nerve fiber layer (DONFL) appearance features numerous arcuate striae after vitrectomy for idiopathic epiretinal membrane or macular hole. We studied the relation between the DONFL appearance and internal limiting membrane (ILM) peeling and performed static microperimetry to explore the possible mechanisms underlying the DONFL appearance.

DESIGN

Prospective cohort study.

PARTICIPANTS

Ninety-five eyes of 88 consecutive patients undergoing vitrectomy for idiopathic macular hole.

METHODS

Vitrectomy and gas tamponade were performed with or without ILM peeling. All eyes were examined postoperatively using fundus photography with blue filters. Static microperimetry was performed in 31 eyes with a clearly visible DONFL appearance.

MAIN OUTCOME MEASURE

The postoperative incidence of the DONFL appearance on blue-filtered fundus photographs. The secondary outcome measure included the microperimetry threshold value in the arcuate striae and the surrounding normal retina within the papillomacular bundle.

RESULTS

On blue-filtered photographs, 46 (62.2%) of 74 eyes with ILM peeling exhibited the DONFL appearance, compared with 0 (0%) of 21 eyes without ILM peeling (P = 0.0002). The area of the DONFL appearance was limited to the area of ILM peeling. There was no difference in the microperimetry threshold value between the arcuate striae and the surrounding normal retina (P = 0.9312).

CONCLUSION

The present study indicates that the DONFL appearance might be related to ILM peeling and is not associated with the loss of optic nerve fibers. These results are consistent with the suggestion that the DONFL appearance might be caused by cleavage of the optic nerve fiber bundles due to damage to the Müller cells, which are in close contact with the ILM and act to maintain the close proximity of the nerve fiber bundles.

Dissociated optic nerve fiber layer appearance after internal limiting membrane peeling for idiopathic macular holes

PURPOSE

To investigate the characteristics and incidence of a dissociated optic nerve fiber layer (DONFL) appearance in eyes after idiopathic macular hole surgery.

DESIGN

Retrospective, nonrandomized, comparative interventional case series.

PARTICIPANTS

Ninety-one eyes with idiopathic macular holes that were closed after 1 pars plana vitrectomy were studied. Among these, 67 eyes had the internal limiting membrane (ILM) peeled (ILM-peeled), and 24 did not have the ILM peeled (ILM-unpeeled).

METHODS

All patients received a complete ophthalmologic examination and color fundus photography preoperatively and postoperatively. Twenty ILM-peeled eyes and 9 ILM-unpeeled eyes were also examined by optical coherence tomography (OCT3), microperimetry by scanning laser ophthalmoscope (SLO), and macular sensitivity measurements by Humphrey visual field testing more than 4 months after the vitrectomy.

MAIN OUTCOME MEASURES

Development of a DONFL on fundus photographs and OCT3, and the functional evaluation of a DONFL by best-corrected visual acuity, SLO-microperimetry, and Humphrey visual field testing.

RESULTS

In 67 ILM-peeled eyes, a DONFL appearance was found in 36 eyes (54%) in color fundus photographs. A DONFL appearance was not detected in any of the 24 ILM-unpeeled eyes. Focal dehiscence of the optic nerve fiber layer was found in all 20 examined eyes by OCT3. No scotoma was found corresponding to the DONFL by SLO microperimetry. The best-corrected visual acuity and macular sensitivity were not significantly different in eyes with and without a DONFL appearance (P>0.05). A DONFL appearance was not detected in all 20 eyes examined within 1 month after surgery, was detected in all 16 eyes examined between 1 and 3 months, and no new cases were detected after 3 months. The DONFL appearance became more distinct until about 6 months after first detection and seemed not to change subsequently.

CONCLUSIONS

The DONFL appearance in about half of the eyes with ILM peeling and none in eyes without ILM peeling strongly suggest that the DONFL appearance is related to ILM peeling. The OCT findings in eyes with no functional abnormality by SLO microperimetry suggested that the DONFL is due to a dehiscence of the optic nerve fiber layer and not a true nerve fiber layer defect.

Spectral imaging of the area of internal limiting membrane peeling

PURPOSE

To evaluate a spectral imaging technique to detect the area of internal limiting membrane (ILM) peeling after vitrectomy for idiopathic macular hole.

MATERIALS AND METHODS

In a prospective study, 15 eyes of 15 patients with idiopathic macular holes were tested. After vitrectomy with ILM peeling, retinal images were taken with color fundus photography, red-free fundus photography, and scanning laser ophthalmoscope imaging at 488 nm, 514 nm, 633 nm, and 780 nm. We calculated the Michelson contrast at the margin of ILM peeling, and each image was rank ordered for the ability to discern the margin of ILM peeling.

RESULTS

The Michelson contrasts in scanning laser ophthalmoscope images at 488 nm and 514 nm were significantly larger than those in images at 633 nm and 780 nm and in the red-free fundus photograph. The scanning laser ophthalmoscope images at 488 nm and 514 nm were rated superior to images at 633 nm and 780 nm, the color fundus photograph, and the red-free fundus photograph.

CONCLUSION

The scanning laser ophthalmoscope images at 488 nm and 514 nm provide a better tool than some of the common clinical means for detection of the area of ILM peeling. This may assist with rapid, noninvasive assessment of ILM peeling.

Optical coherence tomographic findings of dissociated optic nerve fiber layer appearance

PURPOSE

To examine the features of optical coherence tomographic (OCT) findings of dissociated optic nerve fiber layer (DONFL) appearance.

DESIGN

Case-control study.

METHODS

Twenty-four eyes undergoing vitrectomy for idiopathic epiretinal membrane or macular hole were examined postoperatively using OCT.

RESULTS

Thirteen of the 24 eyes exhibited the DONFL appearance. In these 13 eyes, the OCT images indicated dimples in the retinal nerve fiber layer (RNFL) corresponding to each stria. The RNFL thickness (mean +/- SD) at the dimple site was 38.1 +/- 9.3 microm. The depth of each dimple was 28.6 +/- 8.0 microm. The depths of all the dimples were limited to the RNFL thickness. In the other 11 eyes without the DONFL appearance, OCT images showed no distinct dimples.

CONCLUSIONS

The DONFL appearance is caused by dimples the depths of which are limited to the RNFL thickness.