Visual acuity and multifocal electroretinographic changes after arteriovenous crossing sheathotomy for macular edema associated with branch retinal vein occlusion

Vitrectomy for macular edema due to retinal vein occlusion

Purpose: To determine the long-term outcomes of vitrectomy for the macular edema associated with a retinal vein occlusion (RVO).

Methods: This was a retrospective, consecutive, interventional case series. The intraoperative procedures included internal limiting membrane peeling, arteriovenous sheathotomy, radial optic neurotomy, and intravitreal triamcinolone acetonide injection at the end of the surgery. The main outcome was the best-corrected visual acuity (BCVA).

Results: Eight hundred and fifty-four eyes of 854 patients were studied. The eyes consisted of 602 with branch RVO (BRVO), 74 with hemi-central RVO (hemi-CRVO), 87 with nonischemic central retinal vein occlusion (CRVO), and 91 with ischemic CRVO. The mean follow-up period was 68.6 months with a range of 12 to 262 months. The mean BCVA was significantly improved at the final visit (P<0.0001 to 0.0016). The final BCVA improved in 74.4% of the BRVO eyes, in 58.1% of the hemi-CRVO eyes, in 57.4% of the nonischemic CRVO eyes, and in 51.6% of the ischemic CRVO eyes. Multiple regression analysis showed there was no significant relationship between the intraoperative combined procedures and the final BCVA.

Conclusions: The results indicate that the type of RVO is significantly associated with the final BCVA, and vitrectomy is a treatment option to improve and maintain BCVA for a long term.

Combination of Grid Laser Photocoagulation and a Single Intravitreal Ranibizumab as an Efficient and Cost-Effective Treatment Option for Macular Edema Secondary to Branch Retinal Vein Occlusion

Our prospective comparative study of 60 patients aimed to compare the efficacy and feasibility of a single injection ranibizumab versus a single grid laser photocoagulation and versus a combined treatment in macular edema secondary to branch retinal vein occlusion in Asian population. Patients were randomized 1:1:1 (n = 20/group) into grid laser (LAS), the ranibizumab (RAN), and the combination (COM) group. Outcomes were measured as best-corrected visual acuity (BCVA) and central macular thickness (CMT). There were significant differences in mean BCVA between the three groups at 1 week and 1 month (p < 0.05) and in mean CMT at 1 week and 1, 3, 6, and 12 months (p < 0.05). Overall, best results were observed in the combination group. However, the RAN and COM groups achieved very similar results. At 12 months, the CMT in all three groups was decreased compared with baseline (p < 0.05). Our results allow to conclude that the effect of early treatment with a single injection of intravitreal ranibizumab (cost reduction) and the stabilizing effect of grid laser photocoagulation is indeed an effective, feasible, and safe regiment for macular edema secondary to BRVO in Chinese patients, allowing to obviate the need for repeated intravitreal injections and thus reduce the adverse events, therapy duration, patients' malcompliance, and adverse events. A single ranibizumab therapy however is a comparable alternative.

Effects of Dexamethasone Implant on Multifocal Electroretinography in Central Retinal Vein Occlusion

Purpose:

To investigate the effect of Ozurdex (dexamethasone intravitreal implant) on multifocal electroretinography (mfERG) findings during the treatment of macular edema secondary to the central retinal vein occlusion (CRVO).

Methods:

Fifteen eyes of 15 patients who were treated with Ozurdex implant due to CRVO-related macular edema were included in this study. Best corrected visual acuity (BCVA), central macular thickness (CMT), and mfERG evaluations were performed for all patients before injection of Ozurdex. After the injection, BCVA and CMT were measured at months 3 and 6 and mfERG test was performed at month 6 for all patients.

Results:

Pre-implantation mfERG P wave amplitude values of r1, r2, r3, r4 and r5 were 57.8 ± 14.8, 25.1 ± 10.6, 17.2 ± 7.3, 12.0 ± 5.0 and 7.1 ± 3.6 nV/deg², respectively. They increased to 72.9 ± 33.2, 31.2 ± 9.3, 22.6 ± 7.6, 15.6 ± 7.1 and 10.9 ± 5.7 nV/deg², respectively, at month 6. However, these increases were not statistically significant (all P > 0.05). Pre-implantation mfERG r1, r2, r3, r4 and r5 P wave implicit times were 40.1 ± 10.9, 39.4 ± 3, 38.4 ± 3.4, 38.2 ± 3.1 and 39.3 ± 2.2 ms, respectively and these values were measured as 38.9 ± 8.2, 38.4 ± 4.7, 37 ± 3.8, 37.5 ± 4.6 and 37.7 ± 4.7 ms at 6 months. Although there were reductions in P wave implicit times in all rings, they were not statistically significant (all P > 0.05).

Conclusion:

In this prospective study, we found that the Ozurdex implant had no effect on mfERG findings 6 months after insertion for treatment of CRVO-related macular edema.

Fixation stability and implication for multifocal electroretinography in patients with neovascular age-related macular degeneration after anti-VEGF treatment

PURPOSE

To quantify fixation stability in patients with neovascular age-related macular degeneration (nAMD) at baseline, 3 and 6 months after anti-vascular endothelial growth factor (anti-VEGF) treatment and furthermore asses the implications of an unsteady fixation for multifocal electroretinography (mfERG) measurements.

METHODS

Fifty eyes of 50 nAMD patients receiving intravitreal anti-VEGF treatment with either bevacizumab or ranibizumab and eight eyes of eight control subjects were included. Fixation stability measurements were performed with the Eye-Link eyetracking system and the retinal area in degrees² (deg²) containing the 68 % most frequently used fixation points (RAF68) was calculated. MfERG P1 amplitude and implicit time were analyzed in six concentric rings and as a summed response. Patients were examined at baseline, 3 and 6 months. Four different mfERG recordings were performed for the control subjects to mimic an involuntary unstable fixation: normal central fixation, 2.4°, 4.8°, and 7.1° fixation instability.

RESULTS

For control subjects, a fixation instability of 2.4° (corresponding to the central hexagon) did not reduce mfERG ring amplitudes significantly, whereas 4.8° and 7.1° fixation instability reduced the amplitudes significantly in rings 1 and 2 (p < 0.001) as well as in the peripheral rings in the 7.1° instability condition (p < 0.001). Fixation stability improved non-significantly for patients at 3 and 6 months. The size of the retinal area of fixation was at baseline, 3 and 6 months negatively correlated to visual acuity (VA) (r_baseline = -0.65, r_{3 months} = -0.60, and r_{6 months} = -0.66 respectively, p < 0.001) and mfERG amplitudes of the three innermost rings (r_baseline = -0.29, p = 0.042, r_3 months = -0.43, p = 0.003 and r_6 months = -0.31, p = 0.042). The VA cutoff for a fixation area less than 5 deg² (approximately the central hexagon) was 65, 77, and 68 ETDRS letters (corresponding a maximal Snellen equivalent of 0.31) at baseline, 3 and 6 months, respectively.

CONCLUSIONS

MfERG amplitudes in recordings of nAMD patients are at substantial risk of being reduced due to poor fixation as a large number of patients may use a fixation area of more than 5 deg². Fixation monitoring during recording as well as interpretation of results should be performed with care, especially in patients with poor visual acuity.

The Success of Cataract Surgery and the Preoperative Measurement of Retinal Function by Electrophysiological Techniques

Purpose. To study the effect of different electrophysiological methods to evaluate retinal function prior to cataract surgery. Methods. Cataract patients who had no significant other eye disease were chosen. VA, pattern visual evoked potential (PVEP), electroretinogram (ERG), and multifocal electroretinogram (mfERG) responses were measured from 150 cataract patients and 20 control subjects. Results. When the preoperative VA was more than 0.3 in cataract patients, the amplitude of PVEP was not significantly different between cataract and control subjects. The amplitude of central point mfERG was significantly lower in cataract patients compared with control group from HM to 0.8 of preoperative VA. The 95% confidence intervals (CIs) of the amplitudes of center point mfERG were calculated for a range of preoperative VA values. Most of the patients within 95% CI of the center point mfERG had a postoperative VA more than 0.5. Conclusions. The amplitude of central point mfERG in cataract patients was the most relevant parameter to the preoperative VA compared with PVEP and ERG. The 95% CI of the amplitude of central point mfERG for each level of VA could help to evaluate preoperative macular function which is used to predict the outcome of cataract surgery.

Comparative evaluation between ranibizumab combined with laser and bevacizumab combined with laser versus laser alone for macular oedema secondary to branch retinal vein occlusion

Purpose:

To evaluate the anatomical and functional efficacy of combination therapy of intravitreal ranibizumab with laser or intravitreal bevacizumab with laser treatment compared to only laser treatment for macular edema due to branch retinal vein occlusion (BRVO).

Materials and Methods:

Thirty eyes of 30 patients with BRVO of at least 6 weeks duration were randomized into three groups: Group 1 received a single dose of intravitreal Ranibizumab followed by grid laser treatment, Group 2 received a single dose of intravitreal Bevacizumab followed by grid laser treatment, and Group 3 received grid laser alone. Outcomes at 6 months follow-up were reported. Data were collected on best corrected visual acuity (BCVA), central foveal thickness (CFT), and gain in lines of Snellen acuity.

Results:

At 6 month follow-up, the difference in the mean BCVA and CFT between the three treatment groups was not statistically significant (P > 0.05, all comparisons). Six eyes (60%) in Group 1, four eyes (40%) in Group 2 and two eyes (20%) in Group 3 had a statistically significant gain of ≥3 lines of Snellen acuity (P < 0.05).

Conclusion:

Both ranibizumab and bevacizumab combined with laser photocoagulation, resulted in better outcomes than grid laser treatment.

Branch retinal vein occlusion: treatment modalities: an update of the literature

BACKGROUND

Retinal vein occlusion is the second most common retinal vascular disorder after diabetic retinopathy and is considered to be an important cause of visual loss. In this review, our purpose is to update the literature about the treatment alternatives for branch retinal vein occlusion.

METHODS

Eligible papers were identified by a comprehensive literature search of PubMed, using the terms "branch retinal vein occlusion," "therapy," "intervention," "treatment," "vitrectomy," "sheathotomy," "laser," "anti-VEGF," "pegaptanib," "bevacizumab," "ranibizumab," "triamcinolone," "dexamethasone," "corticosteroids," "non-steroids," "diclofenac," "hemodilution," "fibrinolysis," "tPA," and "BRVO." Additional papers were also selected from reference lists of papers identified by the electronic database search.

RESULTS

Treatment modalities were analyzed.

CONCLUSIONS

There are several treatment modalities for branch retinal vein occlusion and specifically for its complications, such as macular edema, vitreous hemorrhage, retinal neovascularization, and retinal detachment, including anti-aggregative therapy and fibrinolysis, isovolemic hemodilution, vitrectomy with or without sheathotomy, peripheral scatter and macular grid retinal laser therapy, non-steroid agents, intravitreal steroids, and intravitreal anti-vascular endothelial growth factors (anti-VEGFs).

Advances in our understanding of diabetic retinopathy

Diabetic retinopathy remains the most common complication of diabetes mellitus and is a leading cause of visual loss in industrialized nations. The clinicopathology of the diabetic retina has been extensively studied, although the precise pathogenesis and cellular and molecular defects that lead to retinal vascular, neural and glial cell dysfunction remain somewhat elusive. This lack of understanding has seriously limited the therapeutic options available for the ophthalmologist and there is a need to identify the definitive pathways that initiate retinal cell damage and drive progression to overt retinopathy. The present review begins by outlining the natural history of diabetic retinopathy, the clinical features and risk factors. Reviewing the histopathological data from clinical specimens and animal models, the recent paradigm that neuroretinal dysfunction may play an important role in the early development of the disease is discussed. The review then focuses on the molecular pathogenesis of diabetic retinopathy with perspective provided on new advances that have furthered our understanding of the key mechanisms underlying early changes in the diabetic retina. Studies have also emerged in the past year suggesting that defective repair of injured retinal vessels by endothelial progenitor cells may contribute to the pathogenesis of diabetic retinopathy. We assess these findings and discuss how they could eventually lead to new therapeutic options for diabetic retinopathy.

Vascular stem cells and ischaemic retinopathies

Retinal ischaemic disorders such as diabetic retinopathy and retinal vein occlusion are common. The hypoxia-related stimuli from oxygen-deprived neural and glial networks can drive expression of growth factors and cytokines which induce leakage from the surviving vasculature and/or pre-retinal and papillary neovascularisation. If left untreated, retinal vascular stasis, hypoxia or ischaemia can lead to macular oedema or fibro-vascular scar formation which are associated with severe visual impairment, and even blindness. Current therapies for ischaemic retinopathies include laser photocoagulation, injection of corticosteroids or VEGF-antibodies and vitreoretinal surgery, however they carry significant side effects. As an alternative approach, we propose that if reparative intra-retinal angiogenesis can be harnessed at the appropriate stage, ischaemia could be contained or reversed. This review provides evidence that reperfusion of ischaemic retina and suppression of sight-threatening sequelae is possible in both experimental and clinical settings. In particular, there is emphasis on the clinical potential for endothelial progenitor cells (EPCs) to promote vascular repair and reversal of ischaemic injury in various tissues including retina. Gathering evidence from an extensive published literature, we outline the molecular and phenotypic nature of EPCs, how they are altered in disease and provide a rationale for harnessing the vascular reparative properties of various cell sub-types. When some of the remaining questions surrounding the clinical use of EPCs are addressed, they may provide an exciting new therapeutic option for treating ischaemic retinopathies.

Long-term study of vascular perfusion effects following arteriovenous sheathotomy for branch retinal vein occlusion

PURPOSE

To evaluate the perfusion effects and long-term visual outcome of pars plana vitrectomy (PPV) combined with arteriovenous sheathotomy (AVS) with or without triamcinolone for nonischaemic branch retinal vein occlusion (NI-BRVO).

METHODS

Prospective, interventional case series of eight patients with NI-BRVO and haemorrhagic macular oedema. Patients underwent PPV and AVS (n = 5), or PPV, AVS and intravitreal triamcinolone (IVT, n = 3). A masked grading technique assessed fundus photographs and fluorescein angiography (FFA) following surgery. Scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) evaluated macular oedema and outer retinal architecture. Main outcomes examined included visual acuity (VA), retinal reperfusion, collateral vessel regression, vascular dilatation, cystoid macular oedema (CMO), and ocular neovascularization.

RESULTS

Seven of eight patients underwent uncomplicated surgery, with increased intraretinal perfusion and reduced engorgement of distal retinal veins. The mean pre-logMAR VA was 0.8 (SD 0.17) and did not improve significantly after surgery (post-logMAR 0.6, SD 0.38; p = 0.11, paired t-test). SLO/OCT showed persistent CMO in four patients, and subfoveal thinning of the photoreceptor layer. Collateral vessels disappeared at the blockage site post-AVS in 7/8 eyes, and this was associated with improved retinal perfusion. Six of eight patients developed epiretinal membrane. No patients developed ocular neovascularization. The average follow-up was 34.5 months.

CONCLUSIONS

PPV with AVS is a safe procedure, and adjunctive IVT had no additional effects on vascular perfusion. Successful decompressive surgery was followed by disappearance of collateral vessels at the BRVO blockage site and was a clinical marker for intravascular reperfusion. Long-term epiretinal gliosis and subfoveal photoreceptor atrophy limited functional and visual recovery.

Enabling Technology for Microvascular Stenting in Ophthalmic Surgery

Microstenting is a potentially revolutionary approach to surgical treatment of microvascular retinal disorders that do not resolve using pharmaceutical treatment. This article presents a novel device called a stent deployment unit (SDU) that aims at enabling microstent placement in ophthalmic surgery. The clinical motivation for this work is highlighted in context of microvascular retinal surgery. The proposed SDU is designed for intraocular adjustment of the approach angle and the position of the stent with respect to the retina. The feasibility of this device is experimentally evaluated on chick chorioallantoic membranes and on agar vascular models. Experiments show dependency on the approach angle with respect to the vasculature and on the mobility of the vasculature. Successful placement of stents was achieved in both experimental media. To the best of our knowledge, this pioneering work is the first to demonstrate successful stent deployment in a scale suitable for retinal surgery. We believe that this technique has the promise of enabling effective vascular treatments for blinding conditions such as central and branch retinal vein occlusion.