Review on surgical management of diabetic macular edema

Mostafa El Manhaly; Ahmed Souka

doi:10.4103/erj.erj_1_22

REVIEW ARTICLE

Year : 2021 | Volume : 8 | Issue : 2 | Page : 44-46

Review on surgical management of diabetic macular edema

Mostafa El Manhaly¹, Ahmed Souka²
¹ iCare Eye Hospital, Alexandria, Egypt
² Department of Ophthalmology Faculty of Medicine, Alexandria University, Alexandria, Egypt

Date of Submission	13-Apr-2022
Date of Acceptance	27-May-2022
Date of Web Publication	01-Sep-2022

Correspondence Address:
Dr. Mostafa El Manhaly
5 Mohamed Sabry Street, Build B, San Stefano, Alexandria
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/erj.erj_1_22

Abstract

Literature review for surgical management for both tractional and non-tractional diabetic macular edema; with and without internal limiting membrane peeling. According to the DRCR prospective study, traction relaxation allowed vision gain and reduction in central foveal thickness in tractional diabetic macular edema. Also data from small scale and pilot studies about the role of pars plana vitrectomy for non-tractional CI-DME management, showed visual gain and edema resolution in both naive and refractory cases. It is concluded that pars plana vitrectomy has a role the management of DME; however, large scale trials are needed to define the role, optimum timing, and patients characteristics for the usage of vitrectomy in non-tractional DME management.

Keywords: Diabetic macular edema, nontractional diabetic macular edema, vitrectomy

How to cite this article:
El Manhaly M, Souka A. Review on surgical management of diabetic macular edema. Egypt Retina J 2021;8:44-6

How to cite this URL:
El Manhaly M, Souka A. Review on surgical management of diabetic macular edema. Egypt Retina J [serial online] 2021 [cited 2023 Jun 4];8:44-6. Available from: https://www.egyptretinaj.com/text.asp?2021/8/2/44/355265

Introduction

Diabetes is a worldwide public health burden affecting approximately 450 million people, of which approximately 97 million suffer from diabetic retinopathy (DR).^[1] Diabetic macular edema (DME) is the most common cause of moderate vision loss in the working-age population and its prevalence is estimated to be 7% in diabetic patients.

The pathogenesis of DME is multifactorial and includes a sequence of complex biochemical processes. DME is the end result of chronic hyperglycemia and advanced glycated end-products, through direct endothelial cell wall damage and the consequent production of vascular endothelial factors (VEGFs); secondary to retinal ischemia, leading to vascular hyperpermeability, and infrared fluorescence. In addition, the advanced glycated end-products induce collagen cross-linking in the cortical vitreous, with anomalous posterior vitreous detachment (PVD) causing vitreoschisis with multilayered vitreous and vitreomacular traction (VMT).

The standard of care for DME has been established by a series of studies in the past 30 years. Initially, it was treated by macular laser according to the early treatment diabetic retinopathy study, reducing moderate visual loss by 50%.^[2],[3] The introduction of anti–VEGF) resulted in a paradigm shift by introducing the concept of vision gain instead of preventing vision loss. Early studies such as RISE and RIDE as well as RESTORE established the safety and efficacy of anti–VEGF in the treatment of DME.^[4],[5] The diabetic retinopathy clinical research (DRCR) retina network also compared anti–VEGF to the standard of care (focal/grid laser) and steroids through the protocol I as well as compared different anti–VEGF medications to each other (bevacizumab vs. ranibizumab vs. aflibercept) through the protocol T.^[6],[7] Steroids, previously used for poorly responding DME patients, were evaluated in protocol U which demonstrated only anatomic but not visual benefits.^[8]

The management of patients with isolated DME unresponsive to laser or intravitreal therapy remains a clinical dilemma. Although anti–VEGF therapy is highly effective for most patients, approximately 40%–50% of all eyes do not fully respond to anti–VEGF treatment for DME despite adequate timely intervention.^[9],[10] At this point in time, there is little evidence to support vitrectomy as an alternative treatment. Although some studies suggest a possible benefit for pars plana vitrectomy (PPV), with or without internal limiting membrane (ILM) peeling, over the natural history of the disease or grid laser, others failed to prove a clinically meaningful benefit.

Tractional Diabetic Macular Edema

DME is classified nowadays into tractional DME; where there is a mechanical cause distorting the foveal contour and causing edema, and nontractional DME which is subclassified into center-involving DME (CI-DME) and noncenter involving DME (NCI-DME).

Tractional DME is caused by VMT, tractional retinal detachments in eyes with proliferative DR (PDR), and associated with epiretinal membranes (ERMs). It is ideally managed through traction release through PPV. This idea was studied in a prospective study by the DRCR in 2010 to evaluate vitrectomy for DME in eyes with at least moderate vision loss and VMT.^[11] In that study, 68% of cases achieved 50% reduction in crystal field theory, 38% gained two or more lines and 22% lost two or more lines. The authors concluded that surgical management for tractional DME is a valid treatment option with good outcomes. However, the study did not evaluate the role of PPV in nontractional DME and whether ILM peeling has any additional benefit. Furthermore, it did not evaluate its role in nontractional DME.

Nontractional Diabetic Macular Edema

A systematic review published in 2017 aimed to compare the results of PPV with ILM peeling and medical treatment for chronic macular edema.^[12] They concluded that PPV with ILM peeling can be considered a treatment option for chronic DME. One possible explanation is that PPV results in better retinal oxygenation with less VEGF production and less DME. Furthermore, the review showed that PPV either with or without preoperative treatments can significantly improve the BCVA or reduce the central macular thickness (CMT) in patients with diffuse DME; whether in tractional or nontractional DME. Furthermore, subretinal fluid (SRF) was found to be one of the good biomarkers for postvitrectomy vision gain.

Another retrospective study of 53 eyes evaluated the effect of vitrectomy on CI-DME of which 18 eyes were treatment-naïve and 35 eyes had previous treatments.^[13] The median visual acuity (VA) improved from baseline (20/100; interquartile range [IQR], 20/63–20/200) at 3 months, followed by stabilization at 12 months (20/63; IQR, 20/32–20/125). The median central subfield thickness (CST) followed a similar course from baseline at 12 months (−279 μm; IQR, 246–339 μm) comparable in size to that reported with serial intravitreal anti–VEGF injections.

A recent meta-analysis explored whether the addition of ILM peeling resulted in better visual and anatomic outcomes in patients with DME.^[14] The study showed that the ILM-peeled group had higher rates of vision improvement (odds ratio [OR] = 1.66, 95% confidence interval [CI]: 1.12–2.46, P = 0.01) and more CMT reduction (OR = 3.89, 95% CI: 1.37–11.11, P = 0.01). In addition, ERM formation was slightly lower in the ILM-peeled group than in the group of vitrectomy without ILM peeling (OR = 0.38, 95%CI: 0.07–2.00, P = 0.25). There were no significant statistical differences in the incidence of complications detected between the two groups.

Parsplana Vitrectomy as a Primary Option for Nontractional Diabetic Macular Edema

The prevalence of PVD is lower in eyes with DME compared to those without DME. Theoretically, vitrectomy with or without membrane removal, may help improve DME through multiple mechanisms including better inner retina oxygenation, less VEGF load, reducing VEGF, and pro-inflammatory cytokines production and relieving traction. A literature review published in 2019 which included studies for DME cases with detached posterior hyaloid face and no VMT, concluded that vitrectomy has a controversial role for the management of treatment-naïve DME.

The VITAL study was a prospective interventional multicenter study that recruited 120 eyes with treatment-naïve DME.^[15] Patients underwent PPV with ILM peeling as a first-line treatment and were followed up for 24 months. At the final follow-up, approximately 43% gained 5 letters or more and a third of the patients gained 10 letters or more. In addition, for every day PPV is postponed, the patient's chances to gain ≥5 letters at 24 months decreased by 1.8%. Predictors for good postvitrectomy response were found to be shorter DME duration and the presence of SRF at baseline. Baseline HbA1c and duration of DM were not associated with final visual acuity. The most common complications were cataract development and elevated intraocular pressure but neither required surgery.

Conclusion

In my opinion, vitrectomy for tractional or non-tractional DME offers a potential treatment option. Tractional DME is treated by traction relaxation through vitrectomy; preferably with ILM peeling to avoid postoperative ERM. For nontractional edema, anti–VEGF intravitreal injections remain the standard of care, and vitrectomy is spared for refractory edema.

However, large-scale prospective studies are needed to define the role of early vitrectomy for nontractional DME.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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