Surgical and other treatments of diabetic macular edema: an update

Microinvasive pars plana vitrectomy combined with internal limiting membrane peeling versus anti-VEGF intravitreal injection for treatment-naïve diabetic macular edema (VVV-DME study): study protocol for a randomized controlled trial

BACKGROUND

Diabetic macular edema (DME) is the main cause of vision loss in diabetic patients. Currently, anti-vascular endothelial growth factor (VEGF) intravitreal injection stands as the first-line therapy for DME. However, some patients exhibit insufficient response to anti-VEGF agents and often require multiple injections, imposing psychological and economic burdens. While microinvasive pars plana vitrectomy (PPV) has been shown to be safe and effective in treating refractory DME, scant research has explored its application to treatment-naïve DME. The purpose of this study is to determine whether early PPV combined with internal limiting membrane (ILM) peeling can lessen the therapeutic burden of DME patients, prevent vision loss, and maintain long-term stabilization of diabetic retinopathy.

METHODS

This is a single-center, prospective, parallel-group, non-inferiority randomized controlled trial involving 102 DME participants. Participants will be randomly assigned to either the study group (PPV combined with ILM peeling) or the control group (conbercept intravitreal injection (IVC)) at a 1:1 ratio, with a scheduled follow-up at 12 months post-operation. Comparative analysis of results between the two groups will be conducted at months 1, 3, 6, and 12 after the intervention. The primary outcomes involve evaluating the changes in central subfield thickness (CST) and best corrected visual acuity (BCVA). The secondary outcomes include assessment of optical coherence tomography (OCT) and OCT angiography (OCTA) biomarkers, re-treatment and adverse events rates, diabetic retinopathy (DR) development, cost-effectiveness analysis, and vision-related quality of life (VRQL).

DISCUSSION

Some patients do not respond well to anti-VEGF drugs and repeated intravitreal injections increase the treatment burden for patients. The VVV study aims to explore whether PPV combined with ILM peeling could become an initial treatment option for treatment-naïve DME patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05728476. Registered on 15 February 2023.

Role of Vitrectomy in Nontractional Refractory Diabetic Macular Edema

Background: Currently, the gold standard of diabetic macular edema (DME) treatment is anti-vascular endothelial growth factor (VEGF) injections, although a percentage of patients do not respond optimally. Vitrectomy with or without internal limiting membrane (ILM) peeling is a well-established treatment for DME cases with a tractional component while its role for nontractional cases is unclear.The aim of this study is to evaluate the role of vitrectomy with or without ILM peeling in nontractional refractory DME.Methods: We performed a retrospective review of twenty-eight eyes with nontractional refractory DME treated with vitrectomy at San Giuseppe Hospital, Milan, between 2016 and 2018. All surgeries were performed by a single experienced vitreoretinal surgeon. In 43.4% of cases, the ILM was peeled. Best corrected visual acuity and optical coherence tomography (OCT) scans were assessed preoperatively and at 6, 12, and 24 months post-vitrectomy. Results: The mean central macular thickness improved from 413.1 ± 84.4 to 291.3 ± 57.6 μm at two years (p < 0.0001). The mean logarithm of the minimum angle of resolution logMAR best-corrected visual acuity (BCVA) improved after two years, from 0.6 ± 0.2 to 0.2 ± 0.1 (p < 0.0001). We found no difference between ILM peeling vs. no ILM peeling group in terms of anatomical (p = 0.8) and visual outcome (p = 0.3). Eyes with DME and subfoveal serous retinal detachment (SRD) at baseline had better visual outcomes at the final visit (p = 0.001). Conclusions:We demonstrated anatomical and visual improvement of patients who underwent vitrectomy for nontractional refractory DME with and without ILM peeling. Improvement was greater in patients presenting subretinal fluid preoperatively.

Diabetic macular edema treatment guidelines in India: All India Ophthalmological Society Diabetic Retinopathy Task Force and Vitreoretinal Society of India consensus statement

Diabetic macular edema (DME) is a common cause of moderate visual impairment among people with diabetes. Due to the rising number of people with diabetes in India, the absolute numbers of people with DME are significant. There are several treatment options for DME, and the choice of treatment is based on the availability of retinal specialists and infrastructure for the delivery of treatment. A major challenge is the out-of-pocket expenditure incurred by patients as most treatment options are costly. Treatment also varies based on the associated ocular and systemic conditions. The All India Ophthalmology Society (AIOS) and the Vitreo-Retinal Society of India (VRSI) have developed this consensus statement of the AIOS DR task force and VRSI on practice points of DME management in India. The objective is to describe the preferred practice patterns for the management of DME considering the different presentations of DME in different clinical scenarios.

Six-month postoperative outcomes of intraoperative OCT-guided surgical cystotomy for refractory cystoid macular edema in diabetic eyes

Purpose

This study evaluated the outcomes of surgical cystotomy for recurrent diabetic cystoid macular edema (CME).

Patients and methods

We analyzed 20 eyes with a clinical diagnosis of diabetic retinopathy and refractory CME. Release of vitreoretinal adhesion, epiretinal membrane (ERM) and internal limiting membrane (ILM) peeling and cystotomy guided by intraoperative optical coherence tomography (iOCT) were performed in every patient. Pars plana vitrectomy was also performed in 17 patients, 11 of whom also underwent lensectomy and intraocular lens implantation. Central retinal thickness (CRT), central minimum macular thickness (CMMT), macular volume (MV) and best-corrected visual acuity (BCVA) were compared preoperatively and 1 and 6 months post surgery.

Results

CRT, CMMT and MV significantly improved 1 and 6 months post surgery in each group (P<0.01). Significant improvements in BCVA were only observed 6 months post surgery (P<0.01). No intra- or postoperative complications were observed in all patients.

Conclusion

CRT, CMMT, MV and BCVA significantly improved 6 months following surgical cystectomy. This implies that iOCT-guided cystotomy could be another treatment option for refractory CME in diabetic eyes.

Diabetic macular oedema

Diabetic macular oedema, characterised by exudative fluid accumulation in the macula, is the most common form of sight-threatening retinopathy in people with diabetes. It affects one in 15 people with diabetes resulting in more than 20 million cases worldwide. Few epidemiological studies have been done to specifically investigate risk factors for diabetic macular oedema, although poor glycaemic and blood pressure control are associated with the presence and development of the disorder. The pathophysiological processes begin with chronic hyperglycaemia, and interplay between vascular endothelial growth factor (VEGF) and inflammatory mediators. Non-invasive imaging using optical coherence tomography has allowed clinicians to detect mild levels of diabetic macular oedema in order to monitor progress and guide treatment. Although focal or grid laser photocoagulation was the traditional mode of treatment, intraocular pharmacotherapy with anti-VEGF agents is now the standard of care. However, these therapies are expensive and resource intensive. Emerging therapeutic strategies include improving efficacy and duration of VEGF suppression, targeting alternative pathways such as inflammation, the kallikrein-kinin system, the angiopoietin-Tie2 system, and neurodegeneration, and using subthreshold and targeted laser therapy. Ongoing research should lead to improvements in screening, diagnosis, and management of diabetic macular oedema.

Surgical treatment for diabetic vitreoretinal diseases: a review

Over the past four decades, advancements in surgical instrumentations and techniques have significantly improved the postoperative anatomical and visual outcomes of patients with various diabetic vitreoretinal diseases. In particular, surgical interventions for previously serious and untreatable blinding proliferative diabetic retinopathy can now be performed, with much better results. The advents of micro incisional vitrectomy system with better visualization system like binocular indirect ophthalmomicroscope and state-of-the-art instrumentation revolutionized the era of diabetic vitrectomy. High-speed vitrectors, finer instruments, chromo-assisted vitrectomy and use of anti-vascular endothelial growth factors not only change the paradigm but also help achieve much better outcome after diabetic vitrectomies. In this review, we will discuss and summarize the indications, surgical considerations, surgical techniques, potential complications and outcomes of vitreoretinal surgery for diabetic eye diseases.

EFFECT OF INTERNAL LIMITING MEMBRANE PEELING DURING VITRECTOMY FOR DIABETIC MACULAR EDEMA: Systematic Review and Meta-analysis

PURPOSE

To evaluate the effect of internal limiting membrane (ILM) peeling during vitrectomy for diabetic macular edema.

METHODS

MEDLINE, EMBASE, and CENTRAL were systematically reviewed. Eligible studies included randomized or nonrandomized studies that compared surgical outcomes of vitrectomy with or without ILM peeling for diabetic macular edema. The primary and secondary outcome measures were postoperative best-corrected visual acuity and central macular thickness. Meta-analysis on mean differences between vitrectomy with and without ILM peeling was performed using inverse variance method in random effects.

RESULTS

Five studies (7 articles) with 741 patients were eligible for analysis. Superiority (95% confidence interval) in postoperative best-corrected visual acuity in ILM peeling group compared with nonpeeling group was 0.04 (-0.05 to 0.13) logMAR (equivalent to 2.0 ETDRS letters, P = 0.37), and superiority in best-corrected visual acuity change in ILM peeling group was 0.04 (-0.02 to 0.09) logMAR (equivalent to 2.0 ETDRS letters, P = 0.16). There was no significant difference in postoperative central macular thickness and central macular thickness reduction between the two groups.

CONCLUSION

The visual acuity outcomes using pars plana vitrectomy with ILM peeling versus no ILM peeling were not significantly different. A larger randomized prospective study would be necessary to adequately address the effectiveness of ILM peeling on visual acuity outcomes.

Ocriplasmin: who is the best candidate?

Enzymatic vitreolysis is currently the focus of attention around the world for treating vitreomacular traction and full-thickness macular hole. Induction of posterior vitreous detachment is an active area of developmental clinical and basic research. Despite exerting an incompletely elucidated physiological effect, ocriplasmin (also known as microplasmin) has been recognized to serve as a well-tolerated intravitreal injection for the treatment of vitreomacular traction and full-thickness macular hole. There are several unexplored areas of intervention where enzymatic vitreolysis could potentially be used (ie, diabetic macular edema). Recent promising studies have included combinations of enzymatic approaches and new synthetic molecules that induce complete posterior vitreous detachment as well as antiangiogenesis. Although no guidelines have been proposed for the use of ocriplasmin, this review attempts to aid physicians in answering the most important question, "Who is the best candidate?"

The Vitreomacular Interface in Diabetic Retinopathy

Diabetic retinopathy (DR) is a leading health concern and a major cause of blindness. DR can be complicated by scar tissue formation, macular edema, and tractional retinal detachment. Optical coherence tomography has found that patients with DR often have diffuse retinal thickening, cystoid macular edema, posterior hyaloid traction, and tractional retinal detachment. Newer imaging techniques can even detect fine tangential folds and serous macular detachment. The interplay of the vitreous and the retina in the progression of DR involves multiple chemokine and other regulatory factors including VEGF. Understanding the cells infiltrating pathologic membranes at the vitreomacular interface has opened up the possibility of new targets for pharmacotherapy. Vitrectomies for DR remain a vital tool to help relieve tension on the macula by removing membranes, improving edema absorption, and eliminating the scaffold for new membrane formation. Newer treatments such as triamcinolone acetonide and VEGF inhibitors have become essential as a rapid way to control DR at the vitreomacular interface, improve macular edema, and reduce retinal neovascularization. These treatments alone, and in conjunction with PRP, help to prevent worsening of the VMI in patients with DR.

Planned foveal detachment technique for the resolution of diffuse diabetic macular edema

PURPOSE

To evaluate the therapeutic efficacy of a novel surgical procedure for diffuse diabetic macular edema (DME), performed in conjunction with conventional vitrectomy.

METHODS

This prospective, interventional case series involved 20 eyes of 18 consecutive DME patients with best-corrected visual acuities (BCVAs) between 0.301 and 1.221 logarithm of the minimal angle of resolution (logMAR) units and central retinal thicknesses (CRTs) greater than 275 μm. After vitrectomy, a small retinal detachment was made in the macula by injecting 50-100 μl balanced salt solution into the subretinal space using a 38-gauge needle. Before finishing the surgery, fluid-air exchange was performed. Patients were asked to remain in prone position for 1 day postoperatively. The main outcome measures were CRT and BCVA.

RESULTS

The mean CRT of 554.6 ± 152.7 μm before surgery significantly decreased to 295.6 ± 92.5 μm (p < 0.0001) 1 week after surgery and to 185.8 ± 67.4 μm (p < 0.0001) at 6 months after surgery. The CRT was less than 250 μm in 18 eyes (90 %) at 6 months after surgery. The mean BCVA before surgery (0.706 ± 0.348) significantly improved at 6 months after surgery (0.431 ± 0.392, p < 0.0001). Postoperative BCVAs improved by more than 0.3 logMAR units in 13 eyes (65 %), remained unchanged in six eyes (30 %) and worsened in one eye (5 %). Macular edema recurred in three eyes (15 %) 2 months after surgery.

CONCLUSIONS

This novel planned foveal detachment technique facilitated a rapid resolution of DME and contributed to improved visual acuity.

Macular hypotrophy after internal limiting membrane removal for diabetic macular edema

PURPOSE

To compare the anatomic and functional effects of three different approaches to nontractional diabetic macular edema.

METHODS

Retrospective comparative study. Sixty eyes of 60 patients diagnosed with cystoid diabetic macular edema and treated with 1.25 mg/mL intravitreal bevacizumab (Group A), laser photocoagulation (Group B), or vitrectomy with inner limiting membrane peeling (Group C) were included in the study. Changes in number of Early Treatment Diabetic Retinopathy Study letters, central macular thickness, largest diameter of the intraretinal cysts (IC), and choroidal thickness were investigated. Analyses were performed during follow-up visits at Months 1, 3, 6, 9, and 12.

RESULTS

Visual acuity only significantly improved in Group A at the last follow-up (P = 0.004). Central macular thickness significantly decreased in every group throughout the follow-up period. Differences in central macular thickness between Groups A and B (P < 0.01), A and C (P < 0.01), and B and C (P < 0.01) were significant. Intraretinal cysts also significantly decreased in each group throughout the follow-up period. Differences in IC size between Groups A and B (P = 0.8), A and C (P = 0.1), and B and C (P = 0.1) were not significant. Choroidal thickness did not undergo any significant change in any group throughout the follow-up period. A significant correlation was also found in Group A between best-corrected visual acuity at month 12 and baseline central macular thickness (R = 0.3; P = 0.006), and in Group B between postoperative best-corrected visual acuity at month 12 and baseline IC size (R = 0.8; P < 0.01, negatively correlated at 92.4%).

CONCLUSION

According to our retrospective data, diabetic macular edema with intraretinal cysts larger than 390 μm should not be treated with vitrectomy with ILM peeling, because this may induce subfoveal atrophy, defined as the "Floor Effect," and subsequent visual deterioration.

Two-year results of a randomized trial of intravitreal bevacizumab alone or combined with triamcinolone versus laser in diabetic macular edema

PURPOSE

The purpose of this study was to report the 24-month findings of a randomized clinical trial comparing intravitreal bevacizumab (IVB) injection alone or in combination with intravitreal triamcinolone acetonide (IVT) versus macular laser photocoagulation (MPC) as a primary treatment for diabetic macular edema.

METHODS

The eyes were randomly assigned to 1 of the 3 study arms: the IVB group, patients who received 1.25 mg IVB; the IVB/IVT group, patients who received 1.25 mg of IVB and 2 mg of IVT; and the MPC group, patients who underwent focal or modified grid laser. Of 150 eyes (50 in each group) in the primary trial, 123, 119, and 113 eyes completed follow-ups at 12, 18, and 24 months, respectively. A total of 39 (78%), 36 (72%), and 38 (76%) eyes in the IVB, IVB/IVT, and MPC groups remained in the study within 24 months, respectively. Retreatment was performed at 3-month intervals whenever indicated. Data from a 24-month follow-up are presented. Changes in best-corrected visual acuity and central macular thickness up to 24 months were the main outcome measures in this study.

RESULTS

Retreatment was required in 37 (94.9%), 27 (75.0%), and 31 (81.6%) eyes, respectively, in the IVB, IVB/IVT, and MPC groups up to 24 months. The significant superiority of visual acuity improvement in the IVB group, which had been noted at Month 6, did not sustain thereafter up to 24 months, and the difference among the groups was not significant at all visits. However, the mean visual acuity improvement was greater in the IVB group than the other groups and in the IVB/IVT group compared with the MPC group. The reduction of central macular thickness was more in the IVB group in relation to the other two treatment groups; however, the difference among the groups was not statistically significant at any of the follow-up visits.

CONCLUSION

In terms of vision improvement, the significant superiority of the IVB over the combined IVB/IVT and MPC treatment that had been observed at Month 6 did not sustain up to 24 months. This means that although IVB treatment may be a better choice than two other options in short term, the magnitude of this beneficial effect diminishes over time.

Pegaptanib Sodium versus Pegaptanib Sodium Combined with Macular Laser Photocoagulation or Laser Alone for Diabetic Macular Edema

Purpose. To report the outcomes after primary intravitreal pegaptanib sodium in patients with diabetic macular edema (DME). Methods. We conduced a retrospective analysis of eyes with DME treated with primary intravitreal pegaptanib sodium (Macugen) (intravitreal pegaptanib group). The results were compared with the ones of eyes treated with intravitreal pegaptanib sodium associated with macular laser photocoagulation (combined treatment group), and the ones of eyes treated with primary macular laser photocoagulation (macular laser photocoagulation group). Results. For the intravitreal pegaptanib group (13 eyes), we found significant changes in mean best-corrected visual acuity (BCVA) and reductions in mean central macular thickness (CMT) at the last follow-up visit (P = .0014 and P = .0001). For the macular laser photocoagulation group (15 eyes), we found no statistically significant changes in mean BCVA and CMT at the last follow-up visit (P > .05). For the combined treatment group (12 eyes), we found no significant changes in mean BCVA at the last follow-up visit (P > .05) despite significant reductions in mean CMT (P = .0188). Conclusion. Intravitreal pegaptanib treatment alone may be superior to macular laser photocoagulation alone and to combined intravitreal pegaptanib treatment associated with macular laser photocoagulation in patients with DME.

Intravitreal bevacizumab (avastin) injection alone or combined with triamcinolone versus macular photocoagulation as primary treatment of diabetic macular edema

PURPOSE

To report the efficacy of a single intravitreal bevacizumab injection alone or in combination with intravitreal triamcinolone acetonide versus macular laser photocoagulation (MPC) as primary treatment of diabetic macular edema (DME).

METHODS

In this randomized, three-arm clinical trial, 103 eyes of 97 patients with clinically significant DME and no previous treatment were enrolled. The eyes were randomly assigned to one of three study arms: the intravitreal bevacizumab (IVB) group, patients who received 1.25 mg of intravitreal bevacizumab (37 eyes); the IVB/IVT group, patients who received 1.25 mg of intravitreal bevacizumab and 2 mg of intravitreal triamcinolone (33 eyes); and the MPC group, patients who underwent focal or modified grid laser (33 eyes). Primary outcome measure was change in visual acuity.

RESULTS

Visual acuity changes +/- SD at 12 weeks were -0.22 +/- 0.23, -0.13 +/- 0.31, and + 0.08 +/- 0.31 logarithm of the minimal angle of resolution in the IVB, IVB/IVT, and MPC groups, respectively. The marginal regression model based on generalized estimating equation analysis demonstrated that the visual acuity changes in the groups were statistically significant at both 6 weeks (P < 0.0001) and 12 weeks (P = 0.024). The significant treatment effect was demonstrated at both 6 weeks and 12 weeks in the IVB group and only at 6 weeks in the IVB/IVT group. Significant central macular thickness (CMT) reduction was observed in eyes in the IVB and IVB/IVT groups only up to 6 weeks; however, CMT changes were not significant in the groups.

CONCLUSION

Up to 12 weeks, intravitreal bevacizumab treatment of patients with DME yielded better visual outcome than laser photocoagulation, although it was not associated with a significant decrease in CMT. No further beneficial effect of intravitreal triamcinolone could be demonstrated. Further clinical trials with longer follow-up are required to evaluate the long-term visual outcomes and complication profiles after primary treatment with such medications.

The polyol pathway as a mechanism for diabetic retinopathy: attractive, elusive, and resilient

The polyol pathway is a two-step metabolic pathway in which glucose is reduced to sorbitol, which is then converted to fructose. It is one of the most attractive candidate mechanisms to explain, at least in part, the cellular toxicity of diabetic hyperglycemia because (i) it becomes active when intracellular glucose concentrations are elevated, (ii) the two enzymes are present in human tissues and organs that are sites of diabetic complications, and (iii) the products of the pathway and the altered balance of cofactors generate the types of cellular stress that occur at the sites of diabetic complications. Inhibition (or ablation) of aldose reductase, the first and rate-limiting enzyme in the pathway, reproducibly prevents diabetic retinopathy in diabetic rodent models, but the results of a major clinical trial have been disappointing. Since then, it has become evident that truly informative indicators of polyol pathway activity and/or inhibition are elusive, but are likely to be other than sorbitol levels if meant to predict accurately tissue consequences. The spectrum of abnormalities known to occur in human diabetic retinopathy has enlarged to include glial and neuronal abnormalities, which in experimental animals are mediated by the polyol pathway. The endothelial cells of human retinal vessels have been noted to have aldose reductase. Specific polymorphisms in the promoter region of the aldose reductase gene have been found associated with susceptibility or progression of diabetic retinopathy. This new knowledge has rekindled interest in a possible role of the polyol pathway in diabetic retinopathy and in methodological investigation that may prepare new clinical trials. Only new drugs that inhibit aldose reductase with higher efficacy and safety than older drugs will make possible to learn if the resilience of the polyol pathway means that it has a role in human diabetic retinopathy that should not have gone undiscovered.

A Pilot Study of Multiple Intravitreal Injections of Ranibizumab in Patients with Center-Involving Clinically Significant Diabetic Macular Edema

OBJECTIVE

To evaluate the biologic activity of multiple intravitreal injections of ranibizumab in patients with center-involving clinically significant diabetic macular edema (DME) and to report any associated adverse events.

DESIGN

Single-center, open-label, dose-escalating pilot study.

PARTICIPANTS

A total of 10 eyes of 10 patients (mean age, 69.3 years [range, 59-81]) with DME involving the center of the macula and best-corrected visual acuity (BCVA) in the study eye between 20/63 and 20/400.

INTERVENTION

Three intravitreal injections of ranibizumab (0.3 mg or 0.5 mg each injection) administered on day 0, month 1, and month 2, and observation until month 24.

MAIN OUTCOME MEASURES

Primary end points were the frequency and severity of ocular and systemic adverse events. Secondary end points were BCVA and measurement of retinal thickness by optical coherence tomography.

RESULTS

Of the 10 patients enrolled, 5 received 0.3-mg and 5 received 0.5-mg ranibizumab. Intravitreal injections of ranibizumab were well tolerated. No systemic adverse events were reported. Five occurrences of mild to moderate ocular inflammation were reported. At month 3, 4 of 10 patients gained > or =15 letters, 5 of 10 gained > or =10 letters, and 8 of 10 gained > or =1 letters. At month 3, the mean decrease in retinal thickness of the center point of the central subfield was 45.3+/-196.3 microm for the low-dose group and 197.8+/-85.9 microm for the high-dose group.

CONCLUSIONS

Ranibizumab appears to be a well-tolerated therapy for patients with DME. This pilot study demonstrates that ranibizumab therapy has the potential to maintain or improve BCVA and reduce retinal thickness in patients with center-involved clinically significant DME.