Residual edema evaluation with ranibizumab 0.5 mg and 2.0 mg formulations for diabetic macular edema (REEF study)

Persistent diabetic macular edema: Definition, incidence, biomarkers, and treatment methods

Intravitreal antivascular endothelial growth factor (anti-VEGF) treatment has drastically improved the visual and anatomical outcomes in patients with diabetic macular edema (DME); however, success is not always guaranteed, and a proportion of these eyes demonstrate persistent DME (pDME) despite intensive treatment. While standardized criteria to define these treatment-resistant eyes have not yet been established, many studies refer to eyes with no clinical response or an unsatisfactory partial response as having pDME. A patient is considered to have pDME if the retinal thickness improves less than 10-25% after 6 months of treatment. A range of treatment options have been recommended for eyes with pDME, including switching anti-VEGF agents, using corticosteroids and/or antioxidant drugs in adjunct with anti-VEGF therapy, and vitrectomy. In addition, multimodal imaging of DME eyes may be advantageous in predicting the responsiveness to treatment; this is beneficial when initiating alternative therapies. We explore the literature on persistent DME regarding its defining criteria, incidence, the baseline biological markers that may be useful in anticipating the response to treatment, and the available treatment options.

Switching between anti-VEGF agents in the management of refractory diabetic macular edema: A systematic review

Refractory diabetic macular edema (DME) to monthly intravitreal anti-vascular endothelial growth factor (VEGF) monotherapy has a prevalence of approximately 40% in landmark clinical trials. Options for these patients include use of intravitreal steroids, focal laser, or switching to an alternative anti-VEGF agent. We summarize the key conclusions from studies analyzing the efficacy of switching anti-VEGF agents for refractory DME. Twenty-four studies were included in analysis. The most common definitions of refractory in the included studies were a central retinal thickness (CRT) greater than 300μm or a reduction in CRT less than 10% after at least 3-6 prior anti-VEGF injections. Switching to intravitreal aflibercept (IVA) from either intravitreal ranibizumab (IVR) or bevacizumab (IVB) is associated with moderate to significant improvement in central subfield thickness and may be an appropriate choice for patients with refractory DME. The improvement in retinal thickness and edema is typically seen after the first 3 injections of IVA post-switch. Switching to IVR has also demonstrated improvement in CRT at 3-6 months post-switch in large sample population studies. Future studies are required to elucidate the ideal time point for a switch in anti-VEGF agent or which patients would benefit from this change.

THE RELATIONSHIP BETWEEN STOPPER POSITION AND INJECTION VOLUME IN RANIBIZUMAB AND AFLIBERCEPT PREFILLED SYRINGES

PURPOSE

To determine the relationship between stopper position and injection volume in aflibercept and ranibizumab prefilled syringes (PFS).

METHODS

Empty aflibercept 2.0 mg PFS and ranibizumab 0.3 mg and 0.5 mg PFS were collected and refilled with saline. The stopper was positioned relative to the preprinted mark, and resulting injection volumes were recorded. The position for double the on-label volume was confirmed with repeated testing. The quantitative relationship between position and volume was calculated.

RESULTS

In ranibizumab PFS, doubling the distance increased the volume injected by 2.6 times. Positioning the stopper 4.0, 3.0, 2.0, and 0 mm proximal to and 1.0 mm distal to the mark injected volumes of 0.13, 0.1, 0.08, 0.05, and 0.03 mL, respectively. The relationship between position (x) and volume (y) was y = 0.019x + 0.048. In aflibercept PFS, doubling the distance increased the volume injected by 3.2 times. Positioning the stopper 2.5, 2.0, 1.0, and 0 mm proximal to and 1.0 mm distal to the mark injected volumes of 0.16, 0.14, 0.11, 0.05, and 0.02 mL, respectively. The relationship between position (x) and volume (y) was y = 0.041x + 0.059.

CONCLUSION

Proper positioning of the stopper at the preprinted mark accurately delivers the on-label volume with both the ranibizumab and aflibercept PFS. However, small variations in stopper position appear to have substantial effects on the volume of drug injected.

Infrared reflectance image-guided laser photocoagulation of telangiectatic capillaries in persistent diabetic macular edema

This study aimed to assess detection rate of telangiectatic capillaries (TelCaps) with infrared reflectance (IR) and optical coherence tomography (OCT) images and to evaluate the clinical efficacy of IR image-guided focal laser photocoagulation of TelCaps in persistent diabetic macular edema (DME). This retrospective case series included 28 eyes of 28 patients with TelCap and persistent DME refractory to intravitreal anti-vascular endothelial growth factor or corticosteroids. The presence of TelCaps was confirmed using IR and OCT images. All patients were followed up for more than 12 months after direct focal laser photocoagulation of the TelCaps. The TelCap closure rate, changes in best-corrected visual acuity, and central subfield thickness were analyzed. On IR imaging, TelCap appeared as a characteristic hyperreflectivity within a hyporeflective spherical lesion in 85.7% of the eyes. After focal laser photocoagulation, the TelCap closure rate was 57.1% at 3 months and 71.4% at 12 months. A significant improvement in visual acuity and reduction in central subfield thickness were observed at three and 12 months after focal laser photocoagulation (all p < 0.05). The characteristic hyperreflectivity within hyporeflective lesions on the IR image in conjunction with OCT helps identify the TelCap. Our results suggest that IR imaging and OCT-guided focal laser photocoagulation of TelCaps can improve functional and anatomical outcomes in persistent DME.

Retrospective Analysis of Treatment Patterns in Pseudophakic Diabetic Macular Oedema Eyes Treated with Anti-VEGF

Methods

We performed a retrospective review of outcomes in 81 pseudophakic eyes with DMO that received at least 6 anti-VEGF injections. We reviewed baseline and posttreatment optical coherence tomography images, visual acuity, prescribing patterns, time taken to deliver anti-VEGF injections, and structural and functional outcomes.

Results

It took an average of 913 ± 454.1 days to deliver a mean of 11.1 ± 4.7 anti-VEGF injections. Time from baseline to receiving the first 6 anti-VEGF injections was longer than 9 months in 74.7% (n = 59/79) of eyes. There was a mean gain of 1.6 letters (−0.03 logMAR) from baseline to the end point. After 5 anti-VEGF intravitreal injections, the mean CMT was 391.9 μm from 474.4 μm at baseline (p < 0.0001). In 52 of 79 eyes (65.8%), more than one type of anti-VEGF agent was used.

Conclusions

The anti-VEGF treatment used to treat these eyes with DMO was suboptimal, a finding consistent with recently published “real-world” data. There was a strong tendency for patients to be switched within the class to a second anti-VEGF agent.

Rho-Kinase Inhibitors for the Treatment of Refractory Diabetic Macular Oedema

Diabetic macular oedema (DMO) is one of the leading causes of vision loss associated with diabetic retinopathy (DR). New insights in managing this condition have changed the paradigm in its treatment, with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) having become the standard therapy for DMO worldwide. However, there is no single standard therapy for all patients DMO refractory to anti-VEGF treatment; thus, further investigation is still needed. The key obstacles in developing suitable therapeutics for refractory DMO lie in its complex pathophysiology; therefore, there is an opportunity for further improvements in the progress and applications of new drugs. Previous studies have indicated that Rho-associated kinase (Rho-kinase/ROCK) is an essential molecule in the pathogenesis of DMO. This is why the Rho/ROCK signalling pathway has been proposed as a possible target for new treatments. The present review focuses on the recent progress on the possible role of ROCK and its therapeutic potential in DMO. A systematic literature search was performed, covering the years 1991 to 2021, using the following keywords: "rho-Associated Kinas-es", "Diabetic Retinopathy", "Macular Edema", "Ripasudil", "Fasudil" and "Netarsudil". Better insight into the pathological role of Rho-kinase/ROCK may lead to the development of new strategies for refractory DMO treatment and prevention.

Ranibizumab for the treatment of diabetic retinopathy

Introduction: Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus and the leading cause of blindness in young adults. Prior to anti-vascular endothelial growth factor (anti-VEGF) agents, the treatment of DR was based on control of systemic factors and laser photocoagulation. Over the past decade, the use of anti-VEGF agents has revolutionized the treatment of DR, including diabetic macular edema (DME).Areas covered: Ranibizumab has been proven to be effective for the treatment of DME in large clinical trials, while patients in these studies have been assessed in terms of DR severity change. In this review, evidence from randomized trials regarding the use of ranibizumab for DR treatment is presented.Expert opinion: A comprehensive presentation of randomized clinical trials evaluating ranibizumab for DR indicates that it is effective and safe, offering improvement of DR severity in both non-proliferative and proliferative forms. However, there is no general consensus regarding the exact treatment regimen in patients with DR, while the effect of ranibizumab on the progression of retinal ischemia remains unclear.

[Anti-VEGF therapy for diabetic retinopathy]

Diabetic retinopathy (DR) is one of the most severe complications of diabetes mellitus, its treatment involves specialists of different areas - endocrinologists, diabetes specialists, therapists, cardiologists, surgeons, anesthesiologists etc. For ophthalmologists the objective is to diagnose ocular pathological changes associated with diabetes mellitus, and to prescribe required treatment in a timely manner. Treatment methods used in DR can be divided into three main groups: laser coagulation of the retina, intravitreal injection of medications - inhibitors of the vascular endothelial growth factor (VEGF) and glucocorticoids, as well as surgical treatment. The present literature review addresses the use of anti-VEGF drugs in the therapy of DR, specifically the latest medications, the most important studies on the treatment of DR and diabetic macular edema (DME), as well as post hoc analysis of such studies, the role of these medications in the therapy of refractory DME and proliferative stage DR. The review also addresses the upcoming strategies for therapy, as well as the importance of medications in prevention of DR and DME.

Visual and anatomic outcomes of sustained single agent anti-VEGF treatment versus double anti-VEGF switching in the treatment of persistent diabetic macular edema

Background

To compare the anatomical and visual outcomes in eyes with persistent diabetic macular edema (DME) after initial anti-VEGF therapy that were retreated continuously with the same anti-VEGF drug versus those that underwent two successive cycles of medication change in anti-VEGF drugs (double anti-VEGF switch).

Methods

Retrospective review of eyes with persistent DME after 3 initial consecutive monthly anti-VEGF injections. This cohort was divided into two groups: Group 1 continued to receive the same initial anti-VEGF drug for at least 18 months while group 2 eyes were switched to different anti-VEGF medications twice. Group 1 was further subdivided into: Group 1A composed of eyes with less than 20% reduction in central subfield thickness (CRT) at month 3; and group 1B eyes with greater than or equal to 20% reduction in CRT. The percentage of eyes that achieved greater than 10 letters visual acuity (VA) gain or loss was recorded as the primary end point (through month 18 in group 1 and month 6 after 2nd switch in group 2).

Results

Group 1A, 1B and group 2 were composed of 24, 18, and 14 eyes respectively. 34.7%, 56.2% and 36.3% of eyes achieved > 10 letters gain, while 4.3%, 6.2% and 27.2% of eyes lost > 10 letters in groups 1A, 1B, and 2, respectively. Analysis of the visual acuity (VA) letter change in this time interval revealed no significant difference between all groups (p = 0.11). Mean VA and CRT measurements at the primary endpoint in all groups were 0.5, 0.39, and 0.47 logMAR (p = 0.44), and 369.7, 279.9, 321 µm, (p = 0.01) respectively.

Conclusions

There was no difference in the visual outcomes between the two treatment strategies in eyes with persistent DME after 3 consecutive anti-VEGF injections. This may indicate that anti-VEGF switching—even if it is done twice—may have comparable clinical outcomes to sustained treatment with one agent.

AFLIBERCEPT FOR PERSISTENT DIABETIC MACULAR EDEMA: Forty-Eight-Week Outcomes

PURPOSE

To evaluate functional and anatomical outcomes after a switch from intravitreal bevacizumab to aflibercept in patients with persistent diabetic macular edema.

METHODS

Prospective, single-arm, open-label clinical trial of patients with persistent diabetic macular edema, despite previous treatment with bevacizumab. Five loading doses of intravitreal aflibercept were administered every 4 weeks with subsequent injections administered every 8 weeks. Patients were reviewed every 4 weeks, and best-corrected visual acuity and central macular thickness were recorded. Primary outcome measures included change in central macular thickness and best-corrected visual acuity at week 48 compared with baseline. Paired t-tests were used to assess change between baseline and follow-up visits.

RESULTS

At baseline, 43 eyes from 43 patients were recruited with a median (interquartile range) of 12 (7-24) previous intravitreal anti-vascular endothelial growth factor injections over a period of 18 (8-34) months. Mean ± SD central macular thickness reduced by 59 ± 114 μm (P = 0.002), and best-corrected visual acuity improved by 3.9 ± 7.0 letters (P = 0.001) after 48 weeks in the 41 patients who completed the trial. Best-corrected visual acuity improvements were more marked in patients who gained ≥5 letters after the first injection (8.9 ± 5.7 vs. 1.8 ± 6.5 letter gain at 48 weeks, P = 0.002), a difference which remained significant after regression analysis with baseline best-corrected visual acuity . Vision gains and central macular thickness reduction were similar in 9 fellow eyes eligible for inclusion being concurrently treated for diabetic macular edema with bevacizumab.

CONCLUSION

Intravitreal aflibercept was effective in improving anatomical and visual outcomes among patients with an incomplete response to intravitreal bevacizumab with 48 weeks of follow-up. Patients with a good early response subsequent to switching had a better improvement in vision at 48 weeks.

Indocyanine green angiography-guided focal navigated laser photocoagulation for diabetic macular edema

PURPOSE

To evaluate the efficacy of indocyanine-green angiography (ICGA)-guided navigated focal laser photocoagulation for diabetic macular edema (DME).

STUDY DESIGN

Prospective, interventional case series.

METHODS

Six patients (8 eyes) were enrolled in this study. Fluorescein angiography (FA) and ICGA were performed using the Heidelberg Retina Angiogram 2 (Heidelberg Engineering). Navigated focal laser photocoagulation was delivered to the microaneurysms on ICGA using Navilas^® (OD-OS GmbH, Germany). Central retinal thickness (CRT) and macular volume (MV) were measured by Cirrus HD-OCT (Carl Zeiss Meditec). At 6 months, the best-corrected visual acuity (BCVA), CRT and MV were compared to the values measured on day 0. The distances from the center of fovea to the closest microaneurysms (MAs) were measured on the pre-planned Navilas^® image.

RESULTS

All eyes had previous treatment history. At 6 months, ICGA-guided navigated focal laser photocoagulation significantly reduced the CRT and the MV (p<0.05), and there was improvement in the BCVA (p<0.05). At 3 months, 5 out of the 8 eyes (63%) underwent additional ICGA-guided navigated focal laser photocoagulation due to remnants of MAs that had been confirmed by ICGA. There was no observed recurrence of edema after the ICGA-guided navigated focal laser photocoagulation during the 6-month follow-up. The mean distance from the center of fovea to the closest MAs was 624.8 ± 377.7 μm (range 336.0-1438.9 μm).

CONCLUSION

Our data suggest ICGA-guided navigated focal laser photocoagulation may be effective for the treatment of DME.

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.

Diabetic macular edema treated with ranibizumab following bevacizumab failure in Israel (DERBI study)

Purpose:

To evaluate the outcome of second-line intravitreal ranibizumab treatment in eyes with diabetic macular edema having persistent edema following initial therapy with intravitreal bevacizumab.

Methods:

Diabetic macular edema treated with ranibizumab following bevacizumab failure in Israel was a retrospective, multi-center study. Consecutive eyes with persistent diabetic macular edema following at least three previous intravitreal bevacizumab injections prior to intravitreal ranibizumab, at least three-monthly intravitreal ranibizumab injections and at least 12 months of follow-up were included. Data collected included demographics, ocular findings, diabetes control, details of intravitreal bevacizumab and ranibizumab injections, and visual and anatomical measurements before and after intravitreal ranibizumab treatment.

Results:

In total, 202 eyes of 162 patients treated at 11 medical centers across Israel were included. Patients received a mean (±standard deviation) of 8.8 ± 4.9 intravitreal bevacizumab injections prior to the switch to intravitreal ranibizumab. A mean of 7.0 ± 2.7 intravitreal ranibizumab injections were given during the 12 months following the switch to intravitreal ranibizumab. The median central subfield retinal thickness (±interquartile range) by spectral-domain optical coherence tomography decreased from 436 ± 162 µm at baseline to 319 ± 113 µm at month 12 (p < 0.001). Median logMAR visual acuity (±interquartile range) improved from 0.40 ± 0.48 at baseline to 0.38 ± 0.40 at month 12 (p = 0.001). Linear regression suggested that higher number of intravitreal ranibizumab injections and higher pre-switch central subfield retinal thickness were associated with favorable visual outcome. Higher number of intravitreal bevacizumab injections and the presence of intraretinal fluid before the switch lessened the odds of favorable outcome.

Conclusion:

Switching from bevacizumab to ranibizumab in persistent diabetic macular edema was associated with anatomical improvement in the majority of eyes and ⩾2 lines of vision improvement in 22% of eyes.

Switching to ranibizumab in diabetic macular oedema refractory to bevacizumab treatment

AIM

To determine the efficacy of switching to ranibizumab in patients with diabetic macular oedema refractory to treatment with bevacizumab, and to evaluate the outcomes when switching back to bevacizumab.

METHODS

A prospective study was conducted that included 43 eyes of 31 patients refractory to previous bevacizumab treatment. The patients were switched to ranibizumab, and optical coherence tomography was performed one month post-injection. Patients showing improvement (>10% reduction in central sub-field thickness) were switched back to bevacizumab, and optical coherence tomography was performed one month post-switch back.

RESULTS

The 34 eyes switched to ranibizumab showed a statistically significant improvement in mean best corrected visual acuity from 0.67±0.39 logMAR to a mean of 0.55±0.36 logMAR (P<.05). In addition, there was a statistically significant decrease in central subfield thickness (CST) from a mean of 475.3±122.8 to a mean of 417.3±109.1 (P<.05). In the 21 eyes that were switched back to bevacizumab, there was no significant difference either in the change in CST or in the change in best corrected visual acuity post-switch back.

CONCLUSION

Switching to ranibizumab in patients improves both the best corrected visual acuity and CST in diabetic patients refractory to previous bevacizumab treatment. This effect is pronounced in patients with increased CST prior to the switch. Switching back to bevacizumab adds no further improvement.

A Prospective Randomized Comparative Dosing Trial of Ranibizumab In Bevacizumab-Resistant Diabetic Macular Edema: The REACT Study

Purpose

To assess the efficacy of ranibizumab for persistent diabetic macular edema (DME) previously treated with bevacizumab and compare monthly vs treat-and-extend (TAE) dosing.

Design

12-month, open-label, prospective randomized comparative dosing study.

Participants

27 participants with persistent foveal-involving DME recently treated with bevacizumab.

Methods

All subjects were to receive three initial monthly 0.3 mg ranibizumab injections before randomization to monthly (n=15) or TAE (n=12) injection protocols over 12 months. Treatment interval was extended by two weeks up to a maximum interval of 12 weeks in the TAE group if central subfield thickness (CST) was ≤ 300 μm or complete absence of intraretinal or subretinal fluid on the macular cube was observed. Follow-up interval was decreased by 2 weeks if CST increased above 300 μm with associated intraretinal and/or subretinal fluid.

Main Outcome Measures

Change in Early Treatment of Diabetic Retinopathy Study (ETDRS) best corrected visual acuity (BCVA), CST, adverse events.

Results

Prior to study enrollment, subjects received an average of 8.6 bevacizumab injections. At month 12, mean ETDRS BCVA improved by + 5.3 letters (p<0.05) and mean CST decreased by -99.6 μm (p<0.01) in all patients. At study exit, 18.5 % of subjects gained ≥ 3 lines of vision and 3.7% of subjects lost ≥ 3 lines. Patients treated via the TAE protocol gained +8.4 letters and decreased CST by -120.2 μm whereas those treated by monthly injection gained +2.7 letters and decreased CST by -83.1 μm at month 12.

Conclusions

Following conversion to ranibizumab in eyes with persistent DME refractory to bevacizumab, significant functional and anatomic improvements were noted. Visual and anatomical outcomes were similar in TAE and monthly treatment protocols.

Clinical pharmacology of intravitreal anti-VEGF drugs

Clinical efficacy of intravitreal anti-VEGF drugs has been widely demonstrated in several angiogenesis-driven eye diseases including diabetic macular edema and the neovascular form of age-related macular degeneration. Pegaptanib, ranibizumab, and aflibercept have been approved for use in the eye, whereas bevacizumab is widely used by ophthalmologists to treat patients "off-label". These drugs are active in the nanomolar to picomolar range; however, caution is required when establishing the rank order of affinity and potency due to in vitro inter-experimental variation. Despite the small doses used for eye diseases and the intravitreal route of administration may limit systemic side effects, these drugs can penetrate into blood circulation and alter systemic VEGF with unknown clinical consequences, particularly in vulnerable groups of patients. Clinical pharmacokinetics of ocular anti-VEGF agents should therefore be taken into account when choosing the right drug for the individual patient. The gaps in current understanding that leave open important questions are as follows: (i) uncertainty about which drug should be given first, (ii) how long these drugs can be used safely, and (iii) the choice of the best pharmacological strategy after first-line treatment failure. The current review article, based on the information published in peer-reviewed published papers relevant to anti-VEGF treatments and available on the PubMed database, describes in detail the clinical pharmacology of this class of drugs to provide a sound pharmacological basis for their proper use in ophthalmology clinical practice.

Therapeutic Options in Refractory Diabetic Macular Oedema

Diabetic macular oedema (DMO) results from alterations of several biochemical pathways in diabetic eyes. Centre-involving DMO is an important cause of visual loss in diabetes. Anti-vascular endothelial growth factor agents are now the mainstay of centre-involving DMO treatment. Oedema that does not achieve optimal response to these agents occurs in a sizeable proportion of eyes and is called refractory or persistent DMO. Management of refractory DMO is challenging. In this paper, the pathophysiology of DMO, and the definitions used in various studies are summarised. Therapeutic options for refractory DMO management including corticosteroids, laser, combination therapies, and surgery are explored. Novel agents on the horizon for DMO control that are being investigated at present are discussed as well. A literature review was performed and a summary of the research studies for each of the agents is provided in order to guide the reader regarding the existing evidence for their application in DMO. Importance of early recognition of disease and prompt treatment to achieve best visual outcome is discussed. Utility of optical coherence tomography to guide disease diagnosis and monitoring is highlighted. An algorithmic approach for DMO management is described. Finally, the impact that personalized medicine and genetics might have on DMO management is assessed.

Outcomes of switching treatment to aflibercept in patients with macular oedema secondary to central retinal vein occlusion refractory to ranibizumab

PURPOSE

To assess the treatment outcome of switching from ranibizumab to aflibercept intravitreal injections in patients with macular oedema secondary to central retinal vein occlusion (CRVO).

METHODS

A prospective interventional study was conducted in a tertiary retina service in Leicester Royal Infirmary, UK, where patients with CRVO and associated macular oedema were recruited. First-line treatment involved three monthly ranibizumab injections. Non-responders were defined as patients who despite a minimum of three consecutive injections had persistent intraretinal fluid one month after the last injection. In these cases, a treatment change to aflibercept injections on a per-needed basis was decided. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were measured before and after switching of treatment. Follow-up period lasted for a minimum of 24 weeks after switching.

RESULTS

Twenty-nine eyes of 29 patients with refractory macular oedema secondary to CRVO were included. All eyes had an average of 4.5 ranibizumab intravitreal injections in a mean period of 6 months without reduction in intraretinal fluid and/or no visual acuity gain. A significant decrease in mean CRT from 633.67 ± 242.42 to 234.62 ± 78.28 μm and improvement in mean BCVA from 1.34 ± 0.66 log MAR to 0.91 ± 0.73 log MAR were noticed after switching treatment to aflibercept. The average number of aflibercept injections needed for oedema resolution was 2.19.

CONCLUSIONS

Aflibercept is an effective alternative treatment for macular oedema secondary to CRVO refractory to ranibizumab. Good anatomical and functional result can be achieved with few injections. The maintenance of these results after 6 months is yet to be investigated.

PROSPECTIVE RANDOMIZED SUBJECT-MASKED STUDY OF INTRAVITREAL BEVACIZUMAB MONOTHERAPY VERSUS DEXAMETHASONE IMPLANT MONOTHERAPY IN THE TREATMENT OF PERSISTENT DIABETIC MACULAR EDEMA

PURPOSE

To compare intravitreal bevacizumab monotherapy with intravitreal dexamethasone delayed delivery system monotherapy for persistent diabetic macular edema.

METHODS

Single-center, randomized, subject-masked study of eyes with persistent diabetic macular edema, defined as central subfield thickness (CST) >340 μm despite ≥3 anti-vascular endothelial growth factors injections within 5 months. The intravitreal bevacizumab monotherapy (n = 23 eyes) and delayed delivery system monotherapy (n = 27 eyes) groups received treatments q1month and q3months, respectively.

RESULTS

Baseline best-corrected visual acuity and CST were similar in the two groups. At Month 7, the mean final best-corrected visual acuity (mean ± SD) was 65 ± 16 letters (mean Snellen visual acuity 20/50) and 64 ± 11 letters (20/50) (P = 0.619), the mean change in best-corrected visual acuity was +5.6 ± 6.1 and +5.8 ± 7.6 letters (P = 0.785), the mean final CST was 471 ± 157 and 336 ± 89 μm (P = 0.001), and the mean change in CST was -13 ± 105 and -122 ± 120 μm (P = 0.005) in the intravitreal bevacizumab monotherapy and delayed delivery system monotherapy groups, respectively. The number of injections was 7.0 ± 0.2 and 2.7 ± 0.5 (P < 0.001) in the 2 groups.

CONCLUSION

The two groups had similar best-corrected visual acuity gains. The delayed delivery system monotherapy group achieved a significantly greater reduction of CST compared with the intravitreal bevacizumab monotherapy group, with a q3month interval of treatment, and had no recurrent edema at any visit.

Aflibercept in diabetic macular edema: evaluating efficacy as a primary and secondary therapeutic option

The recent results of Protocol T have illustrated the efficacy of aflibercept in the treatment of diabetic macular edema. It also demonstrated that in patients with poor vision (<6/12), aflibercept offers anatomical and visual advantages over ranibizumab and bevacizumab in the first 12 months of treament. At 2 years, the difference between the three drugs decreased with patients with a better baseline VA (69-78) showing a statistically insignificant advantage for ranibizumab compared with aflibercept.These results were achieved using a pro-re nata (PRN) protocol, which was not previously studied in large phase 3 trials, VIVID and VISTA, that chose to compare the 2.0 mg dose in a monthly and bimonthly regimen. In this review article, we analyzed earlier studies such as DAVINCI and VIVID and VISTA to determine which treatment strategy offers the best results; monthly, bimonthly, or PRN. We also studied the different doses for aflibercept used in DAVINCI to determine which is more effective the 0.5 mg dose or the 2.0 mg dose. In addition, we analyzed the recent data from protocol T with regards to visual and anatomic outcomes to try to determine whether these results concur with previous studies. Finally, we discuss the role of aflibercept as a potential alternative to any diabetic macular edema regimen regardless what the primary drug used is.

Diabetic macular oedema: pathophysiology, management challenges and treatment resistance

Diabetic macular oedema (DMO) is the leading cause of vision loss in patients living with diabetes. DMO results from hyperglycaemia-induced activation of pathways that lead to oxidative stress and release of cytokines, impairing the inner and outer blood-retinal barriers. Improved understanding of the pathophysiological mechanisms leading to DMO have led to the development of effective therapies, including vitreoretinal surgery, laser photocoagulation, intravitreal anti-vascular endothelial growth factor drugs and corticosteroids. Advances in imaging, including fluorescein angiography and optical coherence tomography, have also enhanced diagnosis and management of the condition. Despite these advances, there remain patients who do not respond completely to therapy, reflecting the complex pathophysiology of DMO. These patients may be considered treatment-resistant. In this review, we summarise the pathophysiology of DMO, as well as the available treatments and their mechanism of action. Additionally, we focus on treatment-resistant disease and review the literature on potential options for managing this complication of diabetes.

Ranibizumab for Persistent Diabetic Macular Edema after Bevacizumab Treatment

Purpose

To evaluate the efficacy of switching from bevacizumab to ranibizumab in patients with diabetic macular edema (DME).

Methods

This was a retrospective study of patients with DME initially treated with bevacizumab and switched to ranibizumab. Visual acuity (VA) and central retinal thickness (CRT) were retrieved at fixed timepoints prior to and after the switch.

Results

Forty eyes of 32 patients were included in the study. The difference in VA between any of these fixed timepoints was not statistically significant. A significant gain in VA was found in eyes that lost more than 0.1 logMAR during treatment with the last 3 bevacizumab injections. The mean CRT was significantly lower after the first 3 ranibizumab injections and at the final follow-up (p<0.001), a 67 ± 14 μm and 78 ± 18 μm reduction in thickness, respectively.

Conclusions

Switching to ranibizumab resulted in a significant decrease in the CRT of eyes with DME, and should be considered when there is a lack of response or deterioration while on bevacizumab injections. A significant gain in VA was observed in a subgroup of eyes that lost more than one line while receiving the last 3 bevacizumab injections prior to the switch.

Central retinal vein occlusion: modifying current treatment protocols

Central retinal vein occlusion (CRVO) is a common retinal vascular disorder that can result in severe visual acuity loss. The randomized control study, CRUISE, helped establish anti-VEGFs as the standard of care in cases with CRVO. The extension studies for CRUISE; HORIZON and RETAIN showed that not all visual gains are maintained beyond the first year. In addition, patients showed different behavior patterns; with some patients showing complete response with few recurrences, whereas others showed partial or even no response with multiple recurrences. Long-term follow-up demonstrated that patients responding poorly to anti-VEGFs tended to do so early in the course of treatment. It also demonstrated the effectiveness of a pro re nata (PRN) protocol for improving vision and maintaining these gains over long-term follow-ups. The SHORE study further illustrated this point by demonstrating that there were minimal differences in visual outcomes between patients receiving monthly injections and patients being treated PRN. In this review we analyzed the data from the major randomized clinical trials (RCT) that looked at anti-VEGFs as the primary treatment modality in patients with CRVO (CRUISE and the extension studies HORIZON and RETAIN for ranibizumab as well as GALILEO and COPERNICUS for aflibercept). In addition, we looked at SCORE and GENEVA to help determine whether there is a place for steroids as a first line therapy in current treatment practice. We then explored alternative treatment regimens such as laser therapy and switching between anti-VEGF agents and/or steroids for non or partially responding patients. Finally, we propose a simplified modified treatment algorithm for patients with CRVO for better long-term outcomes in all types of responders.

Treatment strategies for refractory diabetic macular edema: switching anti-VEGF treatments, adopting corticosteroid-based treatments, and combination therapy

INTRODUCTION

The pathophysiology of diabetic macular edema (DME) is complex, involving vascular endothelial growth factor (VEGF) and other inflammatory mediators. DME is currently treated first-line with intravitreal anti-VEGF treatments, though some cases are refractory to multiple anti-VEGF treatments.

AREAS COVERED

This article examines the evolution of treatment practices for DME, with discussion of the recent studies that guide treatment for refractory cases of DME. A literature search was performed using the following terms: anti-VEGF, DME, aflibercept, bevacizumab, ranibizumab, refractory macular edema, and VEGF.

EXPERT OPINION

Focal extrafoveal DME may be treated first-line with laser. In patients with center-involving DME and only mild vision loss, consider starting treatment with bevacizumab, especially when cost is an issue, whereas aflibercept may be considered more strongly in patients with moderate visual loss or worse. There are no standard protocols that define 'treatment failure,' but several studies have reported that switching from bevacizumab to either ranibizumab or aflibercept will result in further reduction of CSFT and improvement in BCVA. Further study with prospective randomized trials is warranted to validate these findings. Switching to intravitreal corticosteroids may be of particular benefit to pseudophakic patients. Anti-VEGF combination with sustained-release corticosteroids also appears promising for refractory DME.

The role of aflibercept in the management of diabetic macular edema

Diabetic macular edema (DME) represents one of the leading causes of visual impairment in working-age adults. Although there are several proven treatments available for this condition, pharmacotherapy through the use of intravitreal antivascular endothelial growth factor agents has revolutionized the management of DME over the past decade with superior outcomes compared to laser therapy. This review summarizes the pathophysiology and available treatment options for the management of DME, with an emphasis on the efficacy and safety profile of a single particular intravitreal antivascular endothelial growth factor agent, aflibercept.