Vital Dyes in Vitreomacular Surgery

Retinal detachment

Retinal detachment (RD) occurs when the neurosensory retina, the neurovascular tissue responsible for phototransduction, is separated from the underlying retinal pigment epithelium (RPE). Given the importance of the RPE for optimal retinal function, RD invariably leads to decreased vision. There are three main types of RD: rhegmatogenous, tractional and exudative (also termed serous) RD. In rhegmatogenous RD, one or more retinal breaks enable vitreous fluid to enter the subretinal space and separate the neurosensory retina from the RPE. In tractional RD, preretinal, intraretinal or subretinal membranes contract and exert tangential forces and elevate the retina from the underlying RPE. Finally, in exudative RD, an underlying inflammatory condition, vascular abnormality or the presence of a tumour causes exudative fluid to accumulate in the subretinal space, exceeding the osmotic pump function of the RPE. The surgical management of RD usually involves pars plana vitrectomy, scleral buckling or pneumatic retinopexy. The approach taken often depends on patient characteristics as well as on practitioner experience and clinical judgement. Advances in surgical technology and continued innovation have improved outcomes for many patients. However, even if retinal re-attachment is achieved, some patients still experience decreased vision or other visual symptoms, such as metamorphopsia, that diminish their quality of life. Continued research in the areas of neuroprotection and retinal biology as well as continued surgical innovation are necessary to enhance therapeutic options and outcomes for these patients.

The State of Intraoperative OCT in Vitreoretinal Surgery: Recent Advances and Future Challenges

Since its first introduction more than 30 years ago, optical coherence tomography (OCT) has revolutionized ophthalmology practice, providing a non-invasive in vivo cross-sectional view of the structures of the eye. Mostly employed in the clinical setting due to its tabletop configuration requiring an upright patient positioning, the recent advent of microscope-integrated systems now allows ophthalmologists to perform real-time intraoperative OCT (iOCT) during vitreoretinal surgical procedures. Numerous studies described various applications of this tool, such as offering surgeons feedback on tissue-instrument interactions in membrane peeling, providing structural images in macular hole repair, and showing residual subretinal fluid or perfluorocarbon in retinal detachment surgery. This narrative review aims at describing the state of the art of iOCT in vitreoretinal procedures, highlighting its modern role and applications in posterior segment surgery, its current limitations, and the future perspectives that may improve the widespread adoption of this technology.

Visualization of preretinal membranes using trypan blue in patients with traction retinal detachments

OBJECTIVE

Surgical repair of complex tractional retinal detachments (TRDs) can be challenging due to the difficulty in delineating the fibroglial membranes from the underlying retinal surface. We describe the visual and retinal reattachment rate with the intraoperative use of trypan blue (TB) to visualize proliferative fibrous membranes in patients with TRDs.

DESIGN

Retrospective study.

PARTICIPANTS

Seventeen patients who underwent a pars plana vitrectomy for surgical TRD repair with TB use between January 1, 2005, and December 31, 2020.

METHODS

Patient charts were retrospectively evaluated for surgical details, preoperative and postoperative logMAR best-corrected visual acuity (BCVA) and status of retinal attachment om days 30 and 90 and at the most recent follow-up visit.

RESULTS

In the cohort of 17 patients, TRDs were found to be secondary to proliferative diabetic retinopathy, complications from endophthalmitis, open globe injury, and neovascularization secondary to a retinal vein occlusion. Mean ± SD preoperative BCVA was 1.7 ± 1.7 logMAR (Snellen, 20/1000), whereas postoperative BCVA at the most recent follow-up visit was 1.4 ± 1.2 logMAR (Snellen, 20/500). The use of TB was successful in delineating the proliferative preretinal membranes in 100% of patients, with no residual staining of posterior segment tissues or adverse reactions related to the dye noted at postoperative visits. Eighty-eight percent (15 of 17) and 76% of retinas (13 of 17) were attached at postoperative month 3 and 6 visits, respectively.

CONCLUSION

TB can be a useful adjunct tool to visualize and allow for a thorough removal of tractional fibrous proliferative epiretinal membranes in patients with complex TRDs, possibly yielding better surgical and long-term reattachment outcomes.

Total and horizontal distances of the foveal stereotaxic displacement can be prognostic indicators for patients with idiopathic epiretinal membrane

Introduction

This study aimed to examine the foveal stereo deviations in the different ectopic inner foveal layer (EIFL) stages of idiopathic epiretinal membrane (iERM) and assess its predictive utility for the baseline and postoperative best-corrected visual acuity (BCVA).

Methods

Based on the calculational combination of foveal displacements in the horizontal and vertical axial optical coherence tomography (OCT) images, the foveal stereotaxic displacement was estimated through the total distance (TD, the distance from the foveal bottom to the inner edge of displaced central foveal) and horizontal distance (HD, projection of the TD in the retinal plane). The preoperative TD, HD, and other OCT- and OCT angiography (OCTA)-related indicators were obtained. The correlations between structural parameters and baseline and postoperative BCVA were evaluated through correlation and multiple linear regression analyses.

Results

In patients with advanced EIFL stage, there was a significant increase in the HD, TD, baseline log of the minimum angle of resolution unit for BCVA, central macular thickness (CMT), acircularity index, and incidence of microcystic macular edema (MME; p < 0.05). Further, they showed a decreased foveal avascular zone (FAZ) area and perimeter (p < 0.001). HD, TD, CMT, MME, FAZ area, and FAZ perimeter were significantly correlated with the baseline and postoperative BCVA (p < 0.05). TD had the highest correlation indexic and was an individual predictor of the baseline and postoperative BCVA. Moreover, FD-300 and MME were individual predictors of postoperative BCVA.

Discussion

Stereoscopic foveal deviations significantly correlated with the baseline and postoperative visual acuity. TD may be used as an independent prognostic factor for BCVA.

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

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

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.

Role of Vital Dyes in Chromovitrectomy

ABSTRACT

Chromovitrectomy, the intraocular application of dyes to assist visualization of preretinal tissues during vitreoretinal surgery, was introduced to avoid ocular complications related to internal limiting membrane peeling, inadequate removal of the vitreous, and incomplete removal of epiretinal membranes. Since 2000, chromovitrectomy has become a popular approach among vitreoretinal specialists. The first vital dye used in chromovitrectomy, indocyanine green, facilitated identification of the fine and transparent internal limiting membrane. Following indocyanine green, trypan blue was introduced to identify epiretinal membranes, and triamcinolone acetonide stained the vitreous well. Recently, additional natural dyes such as lutein and anthocyanin from the açaí fruit have been proposed for intraocular application during vitrectomy. The main goal of this review was to study the role of vital stains in chromovitrectomy and report the latest findings in the literature.

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.

Endoscopic vitreoretinal surgery: principles, applications and new directions

Purpose

To analyze endoscopic vitreoretinal surgery principles, applications, challenges and potential technological advances.

Background

Microendoscopic imaging permits vitreoretinal surgery for tissues that are not visible using operating microscopy ophthalmoscopy. Evolving instrumentation may overcome some limitations of current endoscopic technology.

Analysis

Transfer of the fine detail in endoscopic vitreoretinal images to extraocular video cameras is constrained currently by the caliber limitations of intraocular probes in ophthalmic surgery. Gradient index and Hopkins rod lenses provide high resolution ophthalmoscopy but restrict surgical manipulation. Fiberoptic coherent image guides offer surgical maneuverability but reduce imaging resolution. Coaxial endoscopic illumination can highlight delicate vitreoretinal structures difficult to image in chandelier or endoilluminator diffuse, side-scattered lighting. Microendoscopy’s ultra-high magnification video monitor images can reveal microscopic tissue details blurred partly by ocular media aberrations in contemporary surgical microscope ophthalmoscopy, thereby providing a lower resolution, invasive alternative to confocal fundus imaging. Endoscopic surgery is particularly useful when ocular media opacities or small pupils restrict or prevent transpupillary ophthalmoscopy. It has a growing spectrum of surgical uses that include the management of proliferative vitreoretinopathy and epiretinal membranes as well as the implantation of posterior chamber intraocular lenses and electrode arrays for intraretinal stimulation in retinitis pigmentosa. Microendoscopy’s range of applications will continue to grow with technological developments that include video microchip sensors, stereoscopic visualization, chromovitrectomy, digital image enhancement and operating room heads-up displays.

Conclusion

Microendoscopy is a robust platform for vitreoretinal surgery. Continuing clinical and technological innovation will help integrate it into the modern ophthalmic operating room of interconnected surgical microscopy, microendoscopy, vitrectomy machine and heads-up display instrumentation.