The effects of indocyanine green and endoillumination on rabbit retina: an electroretinographic and histological study

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.

Neuroprotective effect of melatonin loaded in ethylcellulose nanoparticles applied topically in a retinal degeneration model in rabbits

We are reporting for the first time the synthesis and application of an innovative nanometric system for the controlled topic release of melatonin in the retina. The ethylcellulose nanocapsules were characterized by diverse physicochemical techniques (scanning electron microscopy, zeta potential, hydrodynamic diameters) and an in vitro release study was done. A complete ex vivo and in vivo trans-corneal permeation and an irritation study were carried out with the new formulations in albino rabbits, to which a retinal degenerative model was induced. The results obtained demonstrate that the in vitro release of melatonin (1 mg/mL and 2 mg/mL) transported by nanocapsules is slower when compared to a solution of melatonin. Greater penetration of melatonin through the cornea was demonstrated by ex vivo and in vivo tests. This can be attributable to an enhanced neuroprotective effect of melatonin on retinal ganglion cells when it is included in ethylcellulose nanocapsules compared to a solution of melatonin. These outstanding findings add promising new perspectives to current knowledge about administrations using nano-technological tools in the treatment of neurodegenerative diseases at the ocular level.

Protective role of melatonin on retinal ganglionar cell: In vitro an in vivo evidences

Oxidative stress triggers ocular neurodegenerative diseases, such as glaucoma or macular degeneration. The increase of reactive oxygen and nitrogen species in retinal ganglion cells (RGCs) causes damage to the structure and function of the axons that make up the optic nerve, leading to cell death arising from apoptosis, necrosis or autophagy in the RCGs. The use of antioxidants to prevent visual neurodegenerative pathologies is a novel and possibly valuable therapeutic strategy. To investigate in vitro and in vivo neuroprotective efficacy of melatonin (MEL) in RGCs, we used a model of oxidative glutamate (GLUT) toxicity in combination with l-butionin-S, R-sulfoximine (BSO), which induces cell death by apoptosis through cytotoxicity and oxidative stress mechanisms. Histological sectioning and immunohistochemical assays using the TUNEL technique were performed to determine the damage generated in affected cells and to observe the death process of RGCs. Whit BSO-GLUT the results revealed a progressive RGCs death without any significant evidence of a decreased retinal function after 9 days of treatment. In this way, we were able to develop a retinal degeneration model in vivo to carry out treatment with MEL and observed an increase in the survival percentage of RGCs, showing that BSO-GLUT could not exert an oxidant effect on cells to counteract the effect of MEL. These findings reveal that MEL has a neuroprotective and antiapoptotic effect as evidenced by the reduction of oxidative stress damage. MEL demonstrated in this model makes it a promising neuroprotective agent for the treatment of ocular neurodegenerative diseases when administered locally.

In vivo, in vitro toxicity and in vitro angiogenic inhibition of sunitinib malate

PURPOSE

To evaluate the in vivo and in vitro toxicity of sunitinib malate, a multikinase inhibitor molecule.

DESIGN

Experimental, Prospective, Controlled.

METHODS

Human retinal pigment epithelial (ARPE-19) and human umbilical vein endothelialcells (HUVECS) were used in a culture toxicity test and exposed to different concentrations of sunitinib malate for 18 hours. The HUVECs also were cultured to evaluate the angiogenesis inhibitory effect of sunitinib malate. Fundus photography and angiographic, electrophysiologic, and histopathologic evaluations with light and electron microscopy were performed in two groups of five rabbits each that received different intravitreal concentrations of the drug. Each rabbit received 0.1 ml of sunitinib malate in the right eye (one group with 12.5 mg/ml, the other group with 25 mg/ml); all animals received 0.1 ml of physiologic saline solution in the left eye. After sacrifice, the eyes were enucleated and fixed with modified Karnovsky solution.

RESULTS

No toxicity related to sunitinib malate was observed using an in vitro model with the 12.5 and 25 mg/ml solutions in HUVEC and ARPE cell cultures. No toxicity was observed in the in vivo model with 12.5 mg/ml, but light microscopy showed that the 25 mg/ml solution damaged the photoreceptors layer. No functional changes in the electroretinogram were observed in any group.

CONCLUSIONS

Sunitinib malate 12.5 mg/ml caused no toxicity in in vivo and in vitro models, but the 25 mg/ml concentration caused retinal changes suggesting toxicity in the in vivo model. Further research with the drug is needed in models of ocular neovascularization.

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.

Outcomes of idiopathic macular epiretinal membrane removal with and without internal limiting membrane peeling: a comparative study

PURPOSE

To compare visual acuity and macular morphology after epiretinal membrane (ERM) removal with and without internal limiting membrane (ILM) peeling.

METHODS

We studied a retrospective interventional case series of 40 eyes in 40 patients with ERM. All patients underwent standard three-port pars plana vitrectomy. In 19 eyes, the ERM alone was removed. In 21 eyes, the ERM was removed and ILM peeling was performed.

RESULTS

Mean best-corrected visual acuity improved significantly in both the non-ILM peeling and the ILM peeling groups (P = 0.001, P = 0.000). Mean central macular thickness (CMT) decreased significantly in both groups (P = 0.001, P = 0.001). However, there was a significant difference in postoperative CMT between the two groups (P = 0.025). The mean postoperative CMT was significantly higher in the ILM peeling group than in the non-ILM peeling group. Sixteen eyes (84.2%) in the non-ILM peeling group had a normal foveal contour with a foveal depression on postoperative optical coherence tomography (OCT), while nine eyes (42.9%) in the ILM peeling group had a foveal depression (P = 0.01).

CONCLUSIONS

Postoperative OCT revealed that thickening of the macula with loss of the normal foveal contour was more frequent in the ILM peeling group. However, these morphological differences did not result in functional differences in terms of visual outcome.

Indocyanine green toxicity of the retina after cataract surgery: a case report

PURPOSE

To report a single case of indocyanine green (ICG) toxicity of the retina after cataract surgery.

METHODS

A patient from an academic clinical practice was observed with visual field testing, fundus photography, optical coherence tomography, and electroretinography (ERG) following the occurrence of ICG toxicity of the retina after cataract surgery. The main outcomes were final visual acuity, visual fields, and ERG result.

RESULTS

ERG revealed initial subnormal dark-adapted response with normalization 6 months after surgery. The pericentral scotoma found by visual field testing disappeared. Fundus photography of the affected eye showed clearing of ICG stains.

CONCLUSIONS

The patient had substantial improvement of ICG-mediated retinal toxicity.

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.

Assessment of macular function by multifocal electroretinography following epiretinal membrane surgery with indocyanine green-assisted internal limiting membrane peeling

PURPOSE

To evaluate the changes in macular function and potential retinal toxicity in epiretinal membrane (ERM) surgery with indocyanine green (ICG)-assisted internal limiting membrane (ILM) peeling using multifocal electroretinography (mfERG).

METHODS

Thirteen eyes of 13 patients were randomly assigned to have ERM surgery with ILM peeling using 0.5 mg/ml or 1.25 mg/ml ICG staining. Patients were examined at baseline and at 3 and 6 months postoperatively. The postoperative mfERG N1 and P1 response amplitudes and peak latencies of various ring eccentricities were assessed and compared with baseline to determine any serial changes.

RESULTS

After surgery, the median best-corrected visual acuity improved from 20/70 at baseline to 20/30 at 6 months postoperatively (Wilcoxon signed-ranks test, P=0.004). At 3 months postoperatively, the 0.5 mg/ml group showed no significant changes in N1 and P1 response amplitudes and peak latencies, whereas the 1.25 mg/ml ICG group showed significant reductions in N1 and P1 response amplitudes compared with baseline. No significant changes in mfERG responses were observed in either group at 6 months after surgery.

CONCLUSIONS

Our mfERG findings suggested that the use of a higher concentration of ICG for ILM staining might result in transient retinal functional impairment postoperatively. The lowest possible concentration of ICG should be used intraoperatively to minimize potential retinal toxicity.

Retinal ganglion cells toxicity caused by photosensitising effects of intravitreal indocyanine green with illumination in rat eyes

AIM

To investigate the effects of indocyanine green (ICG) with or without illumination on rat retinal ganglion cells (RGC) and retinal morphology.

METHODS

Intravitreal injections of 1.0 mg/ml ICG solution were performed in rat eyes with or without subsequent illumination for 5 minutes. Eyes in the control group had intravitreal injections of balanced salt solution with illumination. Retrograde labelling of RGC with 6% Fluoro-Gold was performed 1 month later and RGC densities were compared between the three groups. Light microscopy with measurements of outer nuclear layer (ONL) and inner nuclear layer (INL) thicknesses were also performed and compared.

RESULTS

Eyes with ICG without illumination showed insignificant reduction in RGC density compared with the control group (p = 0.28), whereas a significant decrease in RGC density was found in eyes that had ICG injection with illumination (p = 0.036). A significant increase in ONL thickness was also observed in the ICG with illumination treated eyes compared with the ICG without illumination and the control groups (p<0.001). No significant difference in INL thickness was observed between the three groups.

CONCLUSIONS

Intravitreal injection of 0.1 mg/ml ICG in rat eyes followed by illumination resulted in photosensitising toxicity to RGC. Lower ICG concentration or illumination level should be considered when performing ICG assisted macular surgery.

Vitrectomy and gas tamponade without internal limiting membrane peeling for myopic foveoschisis

AIM

To evaluate the clinical and anatomical outcomes of pars plana vitrectomy and gas tamponade without internal limiting membrane (ILM) peeling in symptomatic patients caused by myopic foveoschisis.

METHODS

Nine eyes in eight highly myopic patients who had myopic foveoschisis with foveal detachment underwent vitrectomy without ILM peeling followed by gas tamponade. Main outcome measures include change in best corrected visual acuity (BCVA) and changes in height of the foveal detachment and resolution of the myopic foveoschisis measured by optical coherence tomography (OCT).

RESULTS

After surgery, BCVA improved in eight eyes with the median BCVA improved from 20/80 to 20/50 (p=0.012). The mean line of visual improvement was 3.6 lines. OCT showed complete resolution of myopic foveoschisis with complete foveal reattachment in seven (77.8%) eyes with partial resolution in two (22.2%) eyes. The mean height of foveal detachment decreased from 505 mum preoperatively to 21 mum postoperatively (p<0.001).

CONCLUSIONS

Vitrectomy without ILM peeling followed by gas tamponade appeared to result in favourable visual and anatomical outcomes for treating myopic foveoschisis in highly myopic eyes. The results are comparable with studies in which ILM removal was performed. Further controlled study will be useful to determine the role of ILM peeling in these patients.