Lutein: a new dye for chromovitrectomy

Vitreoschisis-induced vitreous cortex remnants in proliferative vitreoretinopathy: A comprehensive review from basic research to clinical practice

Proliferative vitreoretinopathy (PVR) significantly impacts the prognosis of rhegmatogenous retinal detachment (RRD), one of the most critical and increasing causes of vision loss in the Western world. Despite advancements in surgical instruments and techniques, the failure rate due to PVR remains substantial, necessitating additional surgeries and often leading to unsatisfactory visual outcomes. This comprehensive review explores the role of vitreoschisis-induced vitreous cortex remnants (VCR) as a critical, previously under-recognised factor contributing to PVR. Vitreoschisis, a phenomenon where the inner lamellae of the posterior vitreous cortex detach while the outermost layers remain attached to the retina, creates VCR that may contain hyalocytes and serve as scaffolds for fibrocellular proliferation. These remnants are difficult to visualise without triamcinolone acetonide (TA) staining, leading to their frequent lack of recognition in clinical practice. Moreover, removing VCR can be challenging and time-consuming, often requiring meticulous surgical techniques to avoid retinal damage and ensure complete elimination. This review consolidates insights from basic research and clinical practice, emphasising the importance of complete vitreous removal and effective VCR detection and removal to mitigate PVR risks. It highlights the histopathological and clinical evidence supporting the hypothesis that VCR, containing hyalocytes, play a pivotal role in preretinal membrane formation. The review also discusses epidemiological data, surgical management strategies and potential future directions, including improved visualisation techniques and the development of new surgical tools and methods. This review aims to improve surgical outcomes and reduce the frequency and burden of RRD-related complications by addressing VCR as a critical factor in PVR.

Clinical significance of signal shadowing during intraoperative optical coherence tomography-assisted vitreoretinal surgery

This study aimed to analyze the clinical significance of signal shadowing during intraoperative optical coherence tomography (iOCT)-assisted vitreoretinal surgery caused by vitreoretinal instruments, tissue dyes, and vitreous substitutes, and to objectively quantify its impact on iOCT imaging. This is a retrospective observational study of postoperative image analysis from one hundred seventeen (117) patients who underwent iOCT-assisted vitrectomy. The image data were divided into three groups: vitreoretinal instruments, tissue dyes, and vitreous substitutes. The data was then processed using graphic software to measure the grade of picture quality distortion and compared to paired image controls without clinically perceptive interference, then analyzed statistically. The intraocular portion of all studied vitreoretinal instruments caused a high average gray level interference compared to controls ranging from 32 to 68% reduction, obscuring the area of interest significantly. The tips of the instruments produced low-grade shadowing, allowing the underlying tissue to be distinguished. The analyzed dyes demonstrated a wide interference range: ICG (- 75.12%), and triamcinolone (- 26.13%) showed dose-dependent high shadowing, while VITREODYNE™ (49.3%) and brilliant blue G (14.06%) exhibited no perceived distortions whilst increasing average gray levels. All analyzed vitreous substitutes (air, SF6, C3F8, PFCL, and silicone oil) showed an insignificant shadowing effect on iOCT. Certain dyes and vitreous substitutes produce a negligible shadowing effect compared to controls and other dyes, providing an advantage during real-time iOCT imaging. All analyzed vitreoretinal instruments showed a significant interference that should prompt the development of new imaging techniques or the implementation of materials with low-grade interference to overcome a clinically relevant shadowing effect on iOCT, maximizing the technology's visual accuracy and surgical diagnostic aid proficiency.

Oxidative Stress and Antioxidant-Based Interventional Medicine in Ophthalmology

The different anatomical compartments of the eye are highly subjected to reactive oxygen species (ROS) generation due to internal factors, such as metabolic high oxygen consumption, as well as environmental factors, including UV light. An antioxidant defense system is endowed in the eye tissues to regulate ROS quantity and activity. When this homeostatic system is overwhelmed, oxidative stress occurs, causing cellular damage, chronic inflammation, and tissue degeneration. It also plays a significant role in the development and progression of various ocular diseases. Understanding the mechanisms underlying oxidative stress in ocular conditions is thus crucial for the development of effective prevention and treatment strategies. To track marketed products based on antioxidant substances as active ingredients, the databases of the European Medicines Agency and the U.S. Food and Drug Administration were consulted. Only a limited number of items were identified, which were either used as therapeutic treatment or during ocular surgery, including antioxidants, synthetical derivatives, or pro-drugs designed to enhance tissue permeation and activity. This review aims to provide an overview of the primary ocular pathologies associated with oxidative stress and of the available pharmacological interventions centered around antioxidant molecules. Such insights are essential for advancing the development of effective prevention and novel treatment approaches.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Translational Relevance

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

Advances in Vitreoretinal Surgery

Advances in vitreoretinal surgery provide greater safety, efficacy, and reliability in the management of the several vitreoretinal diseases that benefit from surgical treatment. The advances are divided into the following topics: scleral buckling using chandelier illumination guided by non-contact visualization systems; sclerotomy/valved trocar diameters; posterior vitrectomy systems and ergonomic vitrectomy probes; chromovitrectomy; vitreous substitutes; intraoperative visualization systems including three-dimensional technology, systems for intraoperative optical coherence tomography, new instrumentation in vitreoretinal surgery, anti-VEGF injection before vitrectomy and in eyes with proliferative diabetic retinopathy, and new surgical techniques; endoscopic surgery; the management of subretinal hemorrhages; gene therapy; alternative techniques for refractory macular hole; perspectives for stem cell therapy and the prevention of proliferative vitreoretinopathy; and, finally, the Port Delivery System. The main objective of this review is to update the reader on the latest changes in vitreoretinal surgery and to provide an understanding of how each has impacted the improvement of surgical outcomes.

PREVALENCE AND RISK FACTORS OF ELLIPSOID ZONE DAMAGE AFTER PARS PLANA VITRECTOMY FOR IDIOPATHIC EPIRETINAL MEMBRANE

PURPOSE

To assess factors associated with external limiting membrane (ELM)/ellipsoid zone (EZ) damage after pars plana vitrectomy (PPV) for epiretinal membrane and evaluate ELM/EZ damage impact on functional and anatomical outcomes.

METHODS

Patients who underwent PPV with epiretinal membrane ± inner limiting membrane peeling were retrospectively analyzed. Best-corrected visual acuity and central macular thickness were longitudinally collected based on the available follow-up. Demographic data, clinical data, and surgical details were included in logistic regression models having ELM/EZ damage as a binary outcome.

RESULTS

Overall, 179 eyes (171 patients) were included; 93 had a 12-month follow-up. Thirty-four eyes (19%) had ELM/EZ damage after surgery; in nine eyes (5%), ELM/EZ damage persisted at 12 months. Phacoemulsification during PPV (odds ratio = 6.97; P = 0.007) and ELM/EZ damage before PPV (odds ratio = 6.91; P = 0.007) were risk factors for postoperative ELM/EZ disruption. Thicker outer nuclear layer (P = 0.002), thicker ectopic inner foveal layer (P < 0.001), and higher endoillumination power (P = 0.03) were associated with slower visual recovery. Inner limiting membrane peeling (P = 0.04) was associated with slower anatomical recovery.

CONCLUSION

Cataract extraction and outer retinal damage before PPV are associated with higher risk of photoreceptor damage postoperatively. The rate of visual improvement varies as a function of retinal layers' distortion before surgery; additional retinal manipulation slows restoration of the macular anatomy.

Effects of Internal Limiting Membrane Peel for Idiopathic Epiretinal Membrane Surgery: A Systematic Review of Randomized Controlled Trials

PURPOSE

The purpose of this study was to compare functional and anatomical outcomes after epiretinal membrane (ERM) peeling with internal limiting membrane (ERM/ILM) peeling and without for the treatment of idiopathic ERM.

DESIGN

Systematic review and meta-analysis.

METHODS

A comprehensive search of Cochrane CENTRAL, MEDLINE Ovid, and Embase Ovid for randomized controlled trials comparing ERM/ILM with ERM was performed. Two independent reviewers selected papers and extracted data. Methodological quality was assessed using the Cochrane Risk of Bias (RobVis) tool. Data was analyzed using RevMan 5.3. Quality of body of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

Seven studies reporting 387 eyes overall were included. A total of 207 eyes (53%) received ERM/ILM. A total of 180 (47%) received ERM. Post-operative visual acuities (logMAR) were not significantly different between ERM/ILM and ERM, with a mean difference (MD) of 0.02 (95% confidence interval [CI]: -0.04 to 0.09; P = .45; I²= 42%; n = 101) at 1 month; 0.03 (95% CI: -0.01 to 0.06; P = .11, I² = 15%; n = 299; High Certainty of Evidence) at 3 months; 0.01 (95% CI: -0.03 to 0.04; P = .72; I² = 21%; n = 317; High Certainty of Evidence) at 6 months; and 0.01 (95% CI: -0.02 to 0.04; P = .49; I² = 39%; n = 234) at 12 months post-operatively. ERM/ILM was significantly associated with lower ERM recurrence at 6-12 months with a relative risk of 0.16 (95% CI: 0.04-0.64; P = .01; I² = 0%; n = 155; Moderate certainty of evidence) and an increased central macular thickness (micrometers) at 12 months with an MD of 20.53 (95% CI: 4.96-36.09; P = .01; I² = 12%; n = 234).

CONCLUSIONS

ERM/ILM and ERM result in similar visual acuity despite subtle differences in anatomical outcomes (central macular thickness). ERM/ILM is associated with a significantly lower rate of ERM recurrence at 6-12 months post-operatively and should be considered where recurrence prevention is the treatment priority.

Evaluation of efficacy and safety of new high-density dyes for chromovitrectomy

The purpose of this study is to evaluate the safety and efficacy of two novel heavy dyes for macular surgery: DoubledyneTM and TwinTM. One eye from each of 144 patients undergoing surgery for macular hole or macular pucker was included in the study. The eyes were randomly divided into two groups according to the dye used during surgery. Best correct visual acuity (BCVA), intraocular pressure (IOP) and retinal morphology assessed by ocular coherence tomography (OCT) were evaluated before and 1, 3, 6 and 12 months after surgery. Only one surgeon performed each operation and provided a score ranging from 1 (poor) to 10 (excellent) for quality of staining and comfort in surgery. Statistical analysis was carried out with SPSS to compare parameters before and after surgery and between the two groups. No statistical differences were recorded in quality of staining (p = 0.11), in surgery comfort (p = 0.17) and total time of surgery (p = 0.44) between the two groups. BCVA statistically improved and central macular thickness (CMT) statistically decreased after surgery in both groups (p < 0.05). No toxic dye-related complications or long-term ones affecting the retina were observed in either group. According to this data, although confirmation in further studies with larger populations and longer follow up is required, DoubledyneTM and TwinTM proved to be safe and effective dyes for macular surgery.

Supercritical Assisted Production of Lutein-Loaded Liposomes and Modelling of Drug Release

In this work, a lipophilic ophthalmic drug, lutein, has been entrapped in liposomes, using a supercritical assisted process. Effects of pressure, temperature, and drug to lipid ratio variation were studied on mean diameters and lutein encapsulation efficiency. Liposomes with diameters between 153 ± 38 and 267 ± 56 nm were produced, and lutein encapsulation efficiencies between 86.5 ± 0.4% and 97.8 ± 1.2% were obtained. A Scanning Electron Microscope confirmed spherical shape and mean dimensions of vesicles. The variation of temperature for the production of liposomes showed a significant impact on lutein retention time in the double lipidic layer. Lutein drug release from liposomes produced at 35 °C ended in almost 4.5 days; whereas, liposomes produced at 40 °C showed a faster lutein release in 3 days; then, vesicles obtained at 45 °C released their lutein content in only 2 days. Drug release raw data were well-fitted using Weibull model (R2 up to 99%).

Vital dyes in macular hole surgery

Currently, surgical techniques, such as internal limiting membrane peeling, are used widely for macular holes, macular puckers, epiretinal membranes, diabetic macular edema, retinal detachment, retinal vein occlusions, vitreomacular traction, optic pit maculopathy, and Terson syndrome. This study aimed to highlight any differences regarding visual acuity and ocular tomography coherence changes after staining the internal limiting membrane with dilutions of Brilliant Blue G vs. lutein/zeaxanthin-based dyes. This study involved 30 eyes of 30 patients who had undergone posterior pole vitrectomy for idiopathic stage 4 macular hole. The study lot was divided in two subgroups, 15 eyes colored with Brilliant Blue and the other 15 eyes colored with lutein and zeaxanthin dyes. The association between visual prognosis, ocular tomography coherence changes and intraocular pressure was analyzed. The surgical treatment with required endoillumination levels and a 2-min period of dye using the Alcon Constellation Vision System had no negative impact on cell viability and improved visual acuity by 30%. Staining makes it easier to remove, to be quick and precise while performing macular surgeries. In has been observed that lutein and zeaxanthin dyes offer an intraoperative protective screen that protects photoreceptors more than Brilliant Blue while performing pars plana vitrectomy. Both study groups had good results in time. Surgical visualization is an evolving technology.

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.

Terminology and Etymology in Oculoplastic Surgery

PURPOSE

To provide a collection of important terms in oculoplastic surgery, their etymology, current usage, and clarification of terms with overlapping or often misconstrued definitions.

METHODS

Commonly employed terms in oculoplastic surgery were collected, and their etymologies were determined. The authors then examined how these terms are being currently used in the published literature to determine how closely their usage matched the origin of the terms, if any terms had developed multiple meanings, or if multiple terms were being used to describe the same concept.

RESULTS

This article assembles in one area much of the important terms in oculoplastic surgery, highlighting how the etymology of the terms both links to their meanings as well as clarifies the appropriate usage of terms that have evolved to develop several different definitions. Special attention is placed on clarifying the correct definitions of closely related but distinct terms.

CONCLUSIONS

Most terms in ophthalmology are used in a uniform manner across the literature with definitions closely matching their etymology, but some terms in oculoplastic surgery are being used in a potentially confusing overlapping manner and warrant clarification.

[Effect of Dyes Containing Lutein on Enhanced Visibility of Epiretinal Pathologies in Intraoperative OCT]

BACKGROUND

Epiretinal membranes are a disorder leading to metamorphopsia and loss in visual function. The gold standard in therapy is vitrectomy with membrane peeling, usually performed with chromovitrectomy. The aim of this study was to examine whether dyes containing lutein are capable of enhancing visualization of epiretinal tissue in intraoperative optical coherence tomography (iOCT).

PATIENTS AND METHODS

This was a prospective study that included 20 eyes of 20 patients with idiopathic epiretinal membranes scheduled for surgery. 23 G pars plana vitrectomy with intraoperative assistance of iOCT was performed in all cases. Staining of epiretinal membranes was performed with dyes containing trypan blue, brilliant blue G and lutein (tripledyne and dualdyne, both Kemin Industries Inc., USA).

RESULTS

In all patients (n = 20), staining of epiretinal tissue was good, and crystalline lutein particles could be well depicted in iOCT compared to soluble lutein that does not enhance visualisation of epiretinal tissue in iOCT.

CONCLUSIONS

The addition of lutein to commonly used dye formulations offers good staining properties and, in case of crystalline lutein, also enhances epiretinal tissue in iOCT.

A new dye based on anthocyanins from the acai fruit (Euterpe oleracea) for chromovitrectomy in humans: clinical trial results

PURPOSE

To test the applicability of the acai dye at a 25% concentration for identifying the posterior hyaloids and internal limiting membranes (ILMs) during pars plana vitrectomy (PPV) in human eyes with macular holes (MHs).

METHODS

This study included 25 patients with chronic idiopathic MHs. The exclusion criteria included glaucoma, previous significant ocular conditions, and previous ocular surgeries except uncomplicated cataract. Ten surgeons performed 23-gauge four-port PPV, phacoemulsification, posterior hyaloid detachment, ILM peeling guided by dye staining, and perfluoropropane injection. The patients remained prone for 5 days postoperatively. The patients were evaluated postoperatively after 1, 30, and 180 days. The surgeons completed a questionnaire regarding the dye's staining abilities.

RESULTS

The posterior hyaloids and ILMs stained purple in all eyes. The final best-corrected visual acuity improved significantly (p < 0.001) from preoperatively (1.37 ± 0.29) to 180 days postoperatively (1.05 ± 0.43). The MHs closed in 76% of eyes.

CONCLUSION

The acai dye at a 25% concentration identified posterior hyaloids and ILMs during PPVs in humans. Dye toxicity was unlikely.

Isolation and Analysis of the Cppsy Gene and Promoter from Chlorella protothecoides CS-41

Phytoene synthase (PSY) catalyzes the condensation of two molecules of geranylgeranyl pyrophosphate to form phytoene, the first colorless carotene in the carotenoid biosynthesis pathway. So it is regarded as the crucial enzyme for carotenoid production, and has unsurprisingly been involved in genetic engineering studies of carotenoid production. In this study, the psy gene from Chlorella protothecoides CS-41, designated Cppsy, was cloned using rapid amplification of cDNA ends. The full-length DNA was 2488 bp, and the corresponding cDNA was 1143 bp, which encoded 380 amino acids. Computational analysis suggested that this protein belongs to the Isoprenoid_Biosyn_C1 superfamily. It contained the consensus sequence, including three predicted substrate-Mg²⁺ binding sites. The Cppsy gene promoter was also cloned and characterized. Analysis revealed several candidate motifs for the promoter, which exhibited light- and methyl jasmonate (MeJA)-responsive characteristics, as well as some typical domains universally discovered in promoter sequences, such as the TATA-box and CAAT-box. Light- and MeJA treatment showed that the Cppsy expression level was significantly enhanced by light and MeJA. These results provide a basis for genetically modifying the carotenoid biosynthesis pathway in C. protothecoides.

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.

Dye solutions based on lutein and zeaxanthin: in vitro and in vivo analysis of ocular toxicity profiles

PURPOSE

To study the safety profile of Lutein/Zeaxanthin(L/Z)-based natural dye solutions in in vitro and in vivo models.

MATERIAL AND METHODS

In vitro cytotoxicity and cellular growth experiments were carried out on ARPE-19 and human corneal epithelial (HCE) cell lines using different L/Z-based dye solutions, either alone or in association with brilliant blue (BB) or trypan blue (TB). Light and transmission electron microscopy studies were performed seven days after intravitreal injection of dye solutions in rabbits. Electroretinogram (ERG) recordings were taken at baseline and before histopathology.

RESULTS

In vitro cytotoxicity assays demonstrated that the different L/Z-based solutions (from 0.3 to 2%), either alone or in association with BB (0.025%) or TB (0.04%), did not significantly alter mitochondrial activity (≤15%) in the cell lines tested. In addition, in vitro cell growth was inhibited by up to 60% depending on the dye solution, and in direct proportion to the concentration assayed. There was no evidence of structural alterations in the neurosensory retina, retinal pigment epithelium (RPE), or choriocapillaris-choroidal complex. b-Wave ERG records showed no significant differences (±15.2%) in comparison with baseline.

CONCLUSIONS

L/Z-based dye solutions demonstrated a safe profile in in vitro and in vivo models, and may be a useful tool for staining intraocular structures.

Soluble lutein in combination with brilliant blue as a new dye for chromovitrectomy

A new dye for vitreoretinal surgery comprised of soluble lutein/zeaxanthin 1 % and brilliant blue 0.025 % is advantageous compared with other dyes currently used for chromovitrectomy, and showed no signs of toxicity at 1 month of follow-up.

PURPOSE

To evaluate the feasibility and safety of a dye [soluble lutein/zeaxanthin (LZ) 1 % and brilliant blue (BB) 0.025 %] for improving removal of vitreous, epiretinal membranes (ERM), and internal limiting membranes (ILM) in humans.

METHODS

We prospectively evaluated 18 eyes treated surgically for a macular hole or ERM. Eighteen surgeons performed chromovitrectomy using the dye, and completed a questionnaire to evaluate the efficacy and safety of the dye. . Examinations included best-corrected visual acuity and intraocular pressure measurements and optical coherence tomography, fluorescein angiography, and autofluorescence performed at baseline and days 1, 7, and 30 postoperatively.

RESULTS

The green dye was deposited on the posterior pole; vigorous dye flushing into the vitreous cavity was unnecessary. All surgeons reported that the ILM stained greenish-blue; 94.4 % reported ILM peeling adequate; the ERM stained poorly. No evidence of toxicity was observed.

CONCLUSION

The new dye deposited on the posterior pole due to its higher density. The ability to stain the ILM was similar to BB. The new dye has ability to stain the vitreous, hyaloid, and especially the ILM satisfactorily. The new dye may be useful during chromovitrectomy.