Vitrectomy for persistent diffuse diabetic macular edema

Vitrectomy as an Adjunct to Treat-and-Extend Anti-VEGF Injections for Diabetic Macular Edema: The Vitrectomy in Diabetic Macular Oedema (VIDEO) Randomized Clinical Trial

Importance

There are reported benefits from vitrectomy for diabetic macular edema (DME); however, data precede anti-vascular endothelial growth therapy (VEGF) therapy, supporting a need to assess the current role of vitrectomy.

Objective

To determine rates of recruitment and efficacy outcomes of vitrectomy plus internal limiting membrane (ILM) peeling adjunctive to treat-and-extend (T&E) anti-VEGF injections for diabetic macular edema (DME).

Design, Setting, and Participants

This was a single-masked, multicenter randomized clinical trial at 21 sites in the United Kingdom from June 2018 to January 2021, evaluating single eyes of treatment-naive patients with symptomatic vision loss from DME for less than 1 year. Inclusion criteria were best-corrected visual acuity (BCVA) Early Treatment Diabetic Retinopathy Study letter score greater than 35 (approximate Snellen equivalent, 20/200 or better) and central subfield thickness (CST) greater than 350 μm after 3 monthly intravitreal injections of ranibizumab or aflibercept. Data analysis was performed in July 2023.

Interventions

Patients were randomized 1:1 into vitrectomy plus standard care or standard care alone and further stratified into groups with vs without vitreomacular interface abnormality. Both groups received a T&E anti-VEGF injection regimen with aflibercept, 2 mg, or ranibizumab, 0.5 mg. The vitrectomy group additionally underwent pars plana vitrectomy with epiretinal membrane or ILM peel within 1 month of randomization.

Main Outcomes and Measures

Rate of recruitment and distance BCVA. Secondary outcome measures were CST, change in BCVA and CST, number of injections, rate of completed follow-up, and withdrawal rate.

Results

Over 32 months, 47 of a planned 100 patients were enrolled; 42 (89%; mean [SD] age, 63 [11] years; 26 [62%] male) completed 12-month follow-up visits. Baseline characteristics appeared comparable between the control (n = 23; mean [SD] age, 66 [10] years) and vitrectomy (n = 24; mean [SD] age, 62 [12] years) groups. No difference in 12-month BCVA was noted between groups, with a 12-month median (IQR) BCVA letter score of 73 (65-77) letters (Snellen equivalent, 20/40) in the control group vs 77 (67-81) letters (Snellen equivalent, 20/32) in the vitrectomy group (difference, 4 letters; 95% CI, -8 to 2; P = .24). There was no difference in BCVA change from baseline (median [IQR], -1 [-3 to 2] letters for the control group vs -2 [-8 to 2] letters for the vitrectomy group; difference, 1 letter; 95% CI, -5 to 7; P = .85). No difference was found in CST changes (median [IQR], -94 [-122 to 9] μm for the control group vs -32 [-48 to 25] μm for the vitrectomy group; difference, 62 μm; 95% CI, -110 to 11; P = .11).

Conclusions and Relevance

Enrollment goals could not be attained. However, with 47 participants, evidence did not support a clinical benefit of vitrectomy plus ILM peeling as an adjunct to a T&E regimen of anti-VEGF therapy for DME.

Trial Registration

isrctn.org Identifier: ISRCTN59902040.

Diabetic Macular Oedema Guidelines: An Australian Perspective

The number of people living with diabetes is expected to rise to 578 million by 2030 and to 700 million by 2045, exacting a severe socioeconomic burden on healthcare systems around the globe. This is also reflected in the increasing numbers of people with ocular complications of diabetes (namely, diabetic macular oedema (DMO) and diabetic retinopathy (DR)). In one study examining the global prevalence of DR, 35% of people with diabetes had some form of DR, 7% had PDR, 7% had DMO, and 10% were affected by these vision-threatening stages. In many regions of the world (Australia included), DR is one of the top three leading causes of vision loss amongst working age adults (20-74 years). In the management of DMO, the landmark ETDRS study demonstrated that moderate visual loss, defined as doubling of the visual angle, can be reduced by 50% or more by focal/grid laser photocoagulation. However, over the last 20 years, antivascular endothelial growth factor (VEGF) and corticosteroid therapies have emerged as alternative options for the management of DMO and provided patients with choices that have higher chances of improving vision than laser alone. In Australia, since the 2008 NHMRC guidelines, there have been significant developments in both the treatment options and treatment schedules for DMO. This working group was therefore assembled to review and address the current management options available in Australia.

Vitrectomy with ILM peeling in diabetic macular edema in one eye vs. intravitreal anti-VEGF injections in the second eye: a comparative study

PURPOSE

The aim of this study was to compare the results of vitrectomy performed in patients' worse eyes with diabetic macular edema to the results of continuous anti-VEGF treatment performed in patients' fellow eyes.

METHODS

A retrospective interventional study of 14 patients with diabetic macular edema in both eyes. The better eye was always qualified for aflibercept injections (group 1), and the worse eye was scheduled for vitrectomy (group 2). The follow-up lasted 12 months. The following parameters were measured: visual acuity (V), central retinal thickness (CRT), maximum retinal thickness (MRT), central choroidal thickness (CCT), superficial fovea avascular zone (sFAZ) and deep fovea avascular zone (dFAZ), and vessel density at the level of superficial (sVD) and deep (dVD) retinal vessels.

RESULTS

None of the analyzed factors differed between groups with statistical significance at any timepoint. The time of recovery of vision was identical in both eyes (F = 0.91, p = 0.449). The final sFAZ was significantly smaller for group 2 (median 196 μm) than for group 1 (median 375 μm; U = 101.0; p = 0.022; r = 0.44).

CONCLUSION

Both techniques resulted in similar improvements in visual acuity and decreases in CRT after 1 year. sFAZ decreased in all eyes, with a higher extent after vitrectomy.

Protective effect of vitrectomy on the course of diabetic retinopathy: A case report

PURPOSE

To hypothesize the protective role of vitrectomy on the natural course of diabetic retinopathy.

METHODS

Case report.

RESULTS

A 66-year-old lady with a history of type 1 diabetes mellitus since the age of 10 was referred for evaluation. She received laser treatment in her left eye for proliferative diabetic retinopathy 6 years earlier, while her right eye underwent vitrectomy for retinal detachment 17 years before. Diabetic retinopathy was found to be substantially asymmetrical, as the vitrectomized right eye had only mild macular edema without significant vascular abnormalities, whereas the left eye had a complete confluent panretinal photocoagulation with advanced atrophic macular changes. Other reasons for this asymmetry, such as axial length disparity, carotid circulation impairment, or history of branch retinal vein occlusion, were not identified.

CONCLUSIONS

Vitreous removal, performed for a reason other than diabetic retinopathy, may inhibit the retinal complications often associated with longstanding diabetes. Further clinical studies should be considered to ascertain such evidence.

The association between different hypoglycemic regimens and postoperative diabetic macular edema after vitrectomy in the Japanese patients with proliferative diabetic retinopathy

PURPOSE

To study the association between different hypoglycemic regimens and postoperative diabetic macular edema (DME).

METHODS

A secondary analysis based on a retrospective cohort study.

RESULTS

In this secondary analysis, 124 eyes from patients with proliferative diabetic retinopathy (PDR) who underwent pars plana vitrectomy (PPV) between January 2008 and September 2012 were included. We found that compared with oral hypoglycemic medication, oral hypoglycemic medication plus insulin treatment revealed an insignificant relationship with postoperative DME (odds ratio [OR]=0.8, 95% confidence interval [CI]: 0.12-5.21, P=0.8167), only insulin treatment revealed a significant association with postoperative DME (OR=0.10, 95% CI: 0.01-0.84, P=0.0337) after adjusted age, sex. After adjusted age, sex, diabetes mellitus (DM) duration, glycosylated hemoglobin (HbA1c), the results did not have obvious changes (OR=0.61, 95% CI: 0.09-4.26, P=0.6187; OR=0.07, 95% CI: 0.01-0.65, P=0.0197). Furthermore, after adjusted age, sex, DM duration, HbA1c, hypertension, intraoperative retinal photocoagulation, vitreous hemorrhage, macular detachment, fibrovascular membrane, intraocular lens implantation and microincision vitrectomy surgery, the results were consistent (OR=0.66, 95% CI: 0.05-9.49, P=0.7621; OR=0.06, 95% CI: 0.00-0.81, P=0.0342). The same trend was observed in these adjusted models as well (p for trend was 0.0254, 0.0141, and 0.0311, respectively).

CONCLUSION

In conclusion, our results of the secondary analysis should be interpreted as a significant association between insulin treatment and reduced risks of postoperative DME in Japanese PDR patients with PPV surgery, compared with oral medications. Well glycemic control with longstanding insulin therapy may be beneficial to reduce the risks of postoperative DME in PDR patients. Our investigation calls for large-scale and long-term prospective clinical studies for a full evaluation of the exact role of insulin in the progression of postoperative DME.

Intravitreal Tissue Plasminogen Activator Injection for Treatment-Resistant Diabetic Macular Edema of the Vitrectomized Eye

Diabetic macular edema (DME) is the main cause of visual loss in patients with diabetic retinopathy. DME has been treated using intravitreal anti-vascular endothelial growth factor (VEGF) drugs, steroids, laser photocoagulation, vitreoretinal surgery, and their combinations. These modalities are generally effective in preserving vision, but they sometimes produce only limited responses in patients with persistent or refractory DME. The levels of various inflammatory factors, including cytokines, chemokines, and extracellular matrices, as well as VEGF in the vitreous fluid, are increased in patients with DME. Excessive fibrinogen/fibrin levels in the vitreous fluid or fibrin deposition in the retina also contribute to DME pathogenesis. Tissue plasminogen activator (t-PA) promotes the degradation of fibrinogen or fibrin. Intravitreal t-PA injection is a commonly used treatment for subretinal hemorrhage secondary to age-related macular degeneration. Intravitreal t-PA injections have previously been used to restore vision by inducing posterior vitreous detachment in patients with DME. Herein, we describe the visual outcomes of intravitreal t-PA injection in a 78-year-old woman with treatment-resistant DME in her vitrectomized eye after several previous treatments. Before the injection, her best-corrected visual acuity (BCVA) was 0.7 logMAR and central foveal retinal thickness (CRT) was 735 μm. At 1 month after the injection, her BCVA was 0.8 logMAR and CRT was 558 μm, and 3 months later, her BCVA was 0.8 logMAR and CRT was 207 μm. Her BCVA was sustained, and CRT showed gradual improvements. These findings suggested the effectiveness of intravitreal t-PA injections for DME in the vitrectomized eye.

Surgical outcomes of vitrectomy for intractable diabetic macular edema

PURPOSE

To investigate clinical outcomes of vitrectomy for intractable diabetic macular edema (DME) in which anti-vascular endothelial growth factor (anti-VEGF) agents or periocular steroid were not effective.

METHODS

This retrospective study examined 27 eyes of 25 cases. The main measurements included changes in visual acuity (VA) and retinal morphology. Vitrectomies were performed using the Constellation System 25G.

RESULTS

Prior to undergoing vitrectomy, patients were treated with anti-VEGF agents or periocular injection of triamcinolone acetonide. The average number of anti-VEGF agent injections was 3.1 ± 2.8. Triamcinolone was used in 15 eyes. There was no significant change in the mean logMAR best-corrected visual acuity (BCVA) between baseline and posttreatment, with values of 0.49 ± 0.29 and 0.55 ± 0.33, respectively (P = 0.31). Compared with preoperative BCVA, postoperative BCVA improved by more than two lines in 4 eyes (14%), remained the same in 17 eyes (63%), and decreased in 6 eyes (23%). Morphologically, retinal thickness improved by more than 50 μm in 16 eyes (59%), remained unchanged in 7 eyes (26%), and increased in 5 eyes (18%). Retinal edema resolved in all of the cases in which macular epiretinal membrane (ERM) or vitreomacular traction (VMT) was detected by optical coherence tomography during pretreatment.

CONCLUSIONS

Vitrectomy can potentially stabilize the retinal morphology in intractable DME and is likely more effective in DME cases accompanied by ERM or VMT.

The Evolving Treatment of Diabetic Retinopathy

Purpose

To review the current therapeutic options for the management of diabetic retinopathy (DR) and diabetic macular edema (DME) and examine the evidence for integration of laser and pharmacotherapy.

Methods

A review of the PubMed database was performed using the search terms diabetic retinopathy, diabetic macular edema, neovascularization, laser photocoagulation, intravitreal injection, vascular endothelial growth factor (VEGF), vitrectomy, pars plana vitreous surgery, antiangiogenic therapy. With additional cross-referencing, this yielded 835 publications of which 301 were selected based on content and relevance.

Results

Many recent studies have evaluated the pharmacological, laser and surgical therapeutic strategies for the treatment and prevention of DR and DME. Several newer diagnostic systems such as optical coherence tomography (OCT), microperimetry, and multifocal electroretinography (mfERG) are also assisting in further refinements in the staging and classification of DR and DME. Pharmacological therapies for both DR and DME include both systemic and ocular agents. Systemic agents that promote intensive glycemic control, control of dyslipidemia and antagonists of the renin-angiotensin system demonstrate beneficial effects for both DR and DME. Ocular therapies include anti-VEGF agents, corticosteroids and nonsteroidal anti-inflammatory drugs. Laser therapy, both as panretinal and focal or grid applications continue to be employed in management of DR and DME. Refinements in laser devices have yielded more tissue-sparing (subthreshold) modes in which many of the benefits of conventional continuous wave (CW) lasers can be obtained without the adverse side effects. Recent attempts to lessen the burden of anti-VEGF injections by integrating laser therapy have met with mixed results. Increasingly, vitreoretinal surgical techniques are employed for less advanced stages of DR and DME. The development and use of smaller gauge instrumentation and advanced anesthesia agents have been associated with a trend toward earlier surgical intervention for diabetic retinopathy. Several novel drug delivery strategies are currently being examined with the goal of decreasing the therapeutic burden of monthly intravitreal injections. These fall into one of the five categories: non-biodegradable polymeric drug delivery systems, biodegradable polymeric drug delivery systems, nanoparticle-based drug delivery systems, ocular injection devices and with sustained release refillable devices. At present, there remains no one single strategy for the management of the particular stages of DR and DME as there are many options that have not been rigorously tested through large, randomized, controlled clinical trials.

Conclusion

Pharmacotherapy, both ocular and systemic, will be the primary mode of intervention in the management of DR and DME in many cases when cost and treatment burden are less constrained. Conventional laser therapy has become a secondary intervention in these instances, but remains a first-line option when cost and treatment burden are more constrained. Results with subthreshold laser appear promising but will require more rigorous study to establish its role as adjunctive therapy. Evidence to support an optimal integration of the various treatment options is lacking. Central to the widespread adoption of any therapeutic regimen for DR and DME is substantiation of safety, efficacy, and cost-effectiveness by a body of sound clinical trials.

Revisiting pars plana vitrectomy in the primary treatment of diabetic macular edema in the era of pharmacological treatment

Diabetic macular edema (DME) is the most common cause of moderate visual loss in diabetic patients. The current treatment of choice for center-involved DME is anti-vascular endothelial growth factor (VEGF) treatment. Most patients that undergo pharmacological inhibition with anti-VEGF agents need multiple monitoring visits that include optical coherence tomography imaging and multiple injections. Despite this intensive treatment, up to 60% of eyes will have persistent DME after six consecutive monthly injections of an anti-VEGF. Its sustainability over the long term has been questioned. Pars plana vitrectomy (PPV) by increasing the vitreous cavity oxygenation, relieving vitreomacular traction, and removing cytokines from the vitreous cavity may cause long-term resolution of DME without the aforementioned concerns in selected cases. Eyes with vitreomacular traction clearly benefit from PPV as the primary treatment. The role of PPV for eyes with DME without tractional elements is less clear and needs to be explored further.

Submacular Injection of Ranibizumab as a New Surgical Treatment for Refractory Diabetic Macular Edema

Purpose

In this study, we describe a new surgical technique for the treatment of refractory DME. The technique consists of vitrectomy with ILM peeling with a subretinal injection of ranibizumab.

Methods

This is a prospective interventional noncomparative study including patients with refractory DME. Included patients were subjected to the new surgical technique of pars plana vitrectomy with subretinal injection of ranibizumab.

Results

The study included 19 eyes with refractory macular edema, in which this novel technique was attempted. There were 10 males and 9 females. The age of the patients ranged from 17 to 67 years with a mean of 55.58 ± 13.242 years. The duration of diabetes before enrollment in the study ranged from 7 to 25 years with a mean of 16.3 years. Preoperatively, the mean CMT of the eyes ranged from 352 to 883 microns with mean ± SD of 498.58 ± 152.16 microns. Postoperatively, this improved significantly to 373.5 ± 100.3, 355.9 ± 89.8, and 365.74 ± 120.12 microns at 1, 3, and 6 months, respectively (p ≤ 0.001 for all).

Conclusion

This novel surgical procedure of vitrectomy with ILM peeling with a subretinal injection of ranibizumab is effective in cases of refractory DME. The study has been registered in Contact ClinicalTrials.gov PRS Identifier: NCT03975088.

Surgical Therapy for Macular Edema: What We Have Learned through the Decades

Macular edema is a leading cause of functional visual loss in retinal vascular or ocular inflammatory diseases. Because persistent macular edema can lead to irreversible retinal damage, multi-approached treatment should be considered to achieve complete resolution of macular edema. With an enhanced understanding of its pathophysiology, numerous therapeutic options have been developed for the management of macular edema over the decades. Although medical therapies account for the mainstay of treatment, surgical approaches with vitrectomy can play an important role in the management of macular edema, depending on its mechanism of fluid accumulation. The index review focuses on the efficacy of surgical therapy for macular edema secondary to various ocular diseases including diabetic retinopathy, uveitis, and retinal vein occlusion, and consequently provides the evidences that may expand the knowledge and support the employment of surgical options.

Vitrectomy Combined with Intraoperative Dexamethasone Implant for the Management of Refractory Diabetic Macular Edema

Purpose

To evaluate the 1-year results of vitrectomy performed in combination with intraoperative dexamethasone implant for tractional and nontractional refractory diabetic macular edema (DME).

Methods

Thirteen eyes from 13 subjects who were diagnosed with tractional DME and 17 eyes from 17 subjects who were diagnosed with nontractional refractory DME underwent vitrectomy and dexamethasone implant injection. Changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT) during the one year following vitrectomy were evaluated in each group. Additionally, changes in intraocular pressure and other complications were investigated postoperatively.

Results

In eyes with tractional DME, a statistically significant improvement in BCVA was noted at 3, 6, and 12 months, and a statistically significant improvement in CMT was noted at 1, 3, 6, and 12 months from baseline after vitrectomy (p < 0.05). In eyes with nontractional refractory DME, a statistically significant improvement in BCVA was noted at 12 months, but there were no significant improvements in CMT despite the tendency to decrease from baseline. Sixteen (53.3%) of the 30 eyes included in this study showed intraocular pressure elevation, which was addressed using antiglaucoma medication, and there were no other severe complications.

Conclusions

Vitrectomy combined with intraoperative dexamethasone implant may be safe and effective in treating DME, especially tractional DME. In this study, patients with nontractional DME required more additional treatments and time for anatomical and functional improvement compared to patients with tractional DME.

Effect of vitreomacular adhesion on the treatment outcomes in the STOP-Uveitis clinical trial for non-infectious uveitis

Purpose

To evaluate the role of vitreomacular adhesion (VMA) in visual and anatomic outcomes in patients with non-infectious uveitis.

Design

Phase 2 clinical trial

Participants

Data from the Safety, Tolerability, and Efficacy of Tocilizumab in Patients with Non-infectious Uveitis (STOP-Uveitis) study was analyzed.

Methods

In the STOP-Uveitis study, patients with non-infectious uveitis (NIU) received monthly intravenous infusions of either 4 or 8 mg/kg tocilizumab until month 6 (M6). Spectral domain optical coherence tomography (SD-OCT) images of patients that completed M6 of the study were analyzed at baseline to stratify the patients by the presence (VMA+) or absence (VMA−) of VMA. Patients with vitreomacular traction (VMT) or epiretinal membrane causing structural abnormalities within center 1 mm were excluded. All images were graded by two independent graders.

Main outcome measures

Mean change in best-corrected visual acuity (BCVA), central retinal thickness (CRT), and vitreous haze (VH) at M6.

Results

Out of 37 patients randomized in the STOP-Uveitis study, 48 eyes (27 patients) were eligible based on the study criteria. At baseline, 19 eyes were classified as VMA+, and 32 eyes were classified as VMA−. The distribution of two doses of TCZ (4 mg/kg and 8 mg/kg) were similar between the two groups. At M6, the mean improvement in BCVA was 2.00 ± 5.3 and 6.50 ± 7.98 letters in the VMA+ and VMA− groups, respectively (p = 0.02). The mean improvement in CRT was 34.85 ± 72.36 and 80.37 ± 157.21 μm in the VMA+ and VMA− groups, respectively (p = 0.18). Similarly, the mean change in VH was − 0.65 ± 0.47 and − 0.76 ± 0.71 in the VMA+ and VMA− groups, respectively (p = 0.32). Out of 16 eyes with VMA at baseline, 3 eyes developed posterior vitreous detachment (PVD) at M6. The mean change in BCVA was significantly higher (p = 0.02), while CRT and VH score were similar (p > 0.05) in eyes with PVD compared to eyes with persistent VMA.

Conclusions

The absence of VMA or development of PVD in eyes with VMA seems to have a beneficial effect on the vision of subjects receiving treatment for uveitis. Therefore, patients with uveitis should be assessed using SD-OCT for the presence of vitreomacular interface abnormalities.

Diabetic macular edema: Evidence-based management

Diabetic macular edema (DME) is the most common cause of vision loss in patients with diabetic retinopathy with an increasing prevalence tied to the global epidemic in type 2 diabetes mellitus. Its pathophysiology starts with decreased retinal oxygen tension that manifests as retinal capillary hyperpermeability and increased intravascular pressure mediated by vascular endothelial growth factor (VEGF) upregulation and retinal vascular autoregulation, respectively. Spectral domain optical coherence tomography (SD-OCT) is the cornerstone of clinical assessment of DME. The foundation of treatment is metabolic control of hyperglycemia and blood pressure. Specific ophthalmic treatments include intravitreal anti-VEGF drug injections, intravitreal corticosteroid injections, focal laser photocoagulation, and vitrectomy, but a substantial fraction of eyes respond incompletely to all of these modalities resulting in visual loss and disordered retinal structure and vasculature visible on SD-OCT and OCT angiography. Efforts to close the gap between the results of interventions within randomized clinical trials and in real-world contexts, and to reduce the cost of care increasingly occupy innovation in the social organization of ophthalmic care of DME. Pharmacologic research is exploring other biochemical pathways involved in retinal vascular homeostasis that may provide new points of intervention effective in those cases unresponsive to current treatments.

Efficacy and safety of vitrectomy with internal limiting membrane peeling for diabetic macular edema: a Meta-analysis

AIM

To evaluate the efficacy and safety of vitrectomy with internal limiting membrane (ILM) peeling for diabetic macular edema (DME).

METHODS

The PubMed, Embase, Web of Science, Cochrane, SionMed, ClinicalTrials.gov, CNKI databases and Wanfang databases, published until Oct. 2017, were searched to identify studies comparing the clinical outcomes following vitrectomy with and without ILM peeling, for treating DME. Pooled results were expressed as odds ratios (ORs) with corresponding 95% confidence intervals (CI) for vitrectomy with and without ILM peeling with regard to best corrected visual acuity (BCVA), central macular thickness (CMT), and complication incidents.

RESULTS

A total of 14 studies involving 857 eyes were included of which three studies were Chinese and the rests were English literatures. Meta-analysis indicated that compared with vitrectomy alone, vitrectomy with ILM peeling could improve BCVA more obviously (OR=1.66, 95%CI: 1.12-2.46, P=0.01) and had higher rate of CMT reduction (OR=3.89, 95%CI: 1.37-11.11, P=0.01). There were significant statistical differences between the two surgical methods for both BCVA and CMT (P<0.05). For the incidence of intraoperative and postoperative complications, the incidence of epiretinal membrane (ERM) was slightly lower in the ILM peeling group than the group without ILM peeling (OR=0.38, 95%CI: 0.07-2.00, P=0.25), although insignificant statistically. Other incidences of overall complications, iatrogenic peripheral retinal break and increased intraocular pressure indicated no significant difference between two groups (OR=1.19, 95%CI: 0.82-1.73, P=0.36; OR=1.21, 95%CI: 0.66-2.21, P=0.53; OR=1.34, 95%CI: 0.75-2.40, P=0.32).

CONCLUSION

Vitrectomy is effective for DME and the effect can be improved by additional ILM peeling, especially for anatomical efficacy, without increasing the incidence of intraoperative and postoperative complications. However, it is imperative to gain more evaluation in the future due to the paucity of prospective randomized study.

Evaluation of Vitrectomy with Planned Foveal Detachment as Surgical Treatment for Refractory Diabetic Macular Edema with or without Vitreomacular Interface Abnormality

Purpose

To evaluate the therapeutic efficacy of subretinal BSS injections done during vitrectomy for refractory diabetic macular edema (DME) resistant to other modes of treatment including previous vitrectomy.

Materials and Methods

A prospective, interventional noncomparative case series in which cases had refractory DME with a central macular thickness (CMT) ≥ 300 μm, despite previous anti-VEGF therapy (ranibizumab or bevacizumab with shifting to aflibercept). Some cases even received intravitreal triamcinolone acetonide injection, before attempting this solution. The study included group 1, surgically naïve eyes, and group 2, cases with persistent edema despite a previous vitrectomy (7 eyes (25%)). The cases were also divided into group a, eyes with normal vitreomacular interface, and group b, with abnormal vitreomacular attachment (VMA) (6 (21.4%)). The 1ry endpoint for this study was the change in CMT after 9–12 months from surgery. The 2ry endpoints were change in BCVA, recurrence of DME, and surgical complications.

Results

The study included 28 eyes, 6 (21.4%) of which suffered from edema recurrence. The mean recorded CMT was 496 ± 88.7 μm and 274.1 ± 31.6 μm preoperatively and postoperatively, respectively. In all eyes, the preoperative mean BCVA in decimal form was 0.2 ± 0.11, which improved significantly to 0.45 ± 0.2. In the end, the CMT of groups 1 and 2 measured 239 μm and 170.8 μm, respectively (p = 0.019). The preoperative BCVA in groups 1 and 2 was 0.16 ± 0.07 and 0.37 ± 0.14, respectively, which improved to a mean of 0.34 ± 0.09 and 0.7 ± 0.16 postoperatively, respectively (p = 0.185).

Conclusion

Vitrectomy with a planned foveal detachment technique was shown to be a promising solution for refractory DME cases with rapid edema resolution. CMT was shown to improve more in eyes where conventional vitrectomy was not attempted. Moreover, cases with VMA resistant to pharmacotherapy was shown to respond well to this technique. The study has been registered in Contact ClinicalTrials.gov PRS Identifier: NCT03345056.

PARS PLANA VITRECTOMY FOR DIABETIC MACULAR EDEMA: A Systematic Review, Meta-Analysis, and Synthesis of Safety Literature

PURPOSE

To assess the risk and benefit of pars plana vitrectomy for diabetic macular edema.

METHODS

The authors conducted a systematic literature review using PubMed, EMBASE, Web of Science, and Cochrane Central Database of Controlled Trials until September 2014. The population was patients with diabetic macular edema, intervention vitrectomy, comparator macular laser or observation, and efficacy outcome visual acuity and central retinal thickness. Safety outcomes were intraoperative and postoperative surgical complications. The efficacy meta-analysis included only randomized controlled trials. The safety analysis included prospective, retrospective, controlled, and uncontrolled studies.

RESULTS

Five studies were eligible for the efficacy meta-analysis (n = 127 eyes) and 40 for the safety analysis (n = 1,562 eyes). Combining follow-up intervals from 6 to 12 months, the meta-analysis found a nonsignificant 2 letter visual acuity difference favoring vitrectomy, and a significant 102 μm greater reduction in central retinal thickness favoring vitrectomy, but a post hoc subgroup analysis found that a 6-month central retinal thickness benefit reversed by 12 months. The most frequent complications were retinal break (7.1%), elevated intraocular pressure (5.2%), epiretinal membrane (3.3%), and vitreous hemorrhage (2.4%). Cataract developed in 68.6% of 121 phakic eyes.

CONCLUSION

Vitrectomy produces structural and functional improvements in select eyes with diabetic macular edema, but the visual gains are not significantly better than with laser or observation. No major safety concerns were identified.

[Intraoperative use of coherence tomography in vitreoretinal surgery]

BACKGROUND

Optical coherence tomography is a useful tool in several diseases. Its intraoperative use with the intention of improving anatomical results has recently been described.

PURPOSE

To determine the usefulness and safety of optical coherence tomography during pars plana vitrectomy for several vitreo-retinal diseases.

MATERIAL AND METHODS

A prospective case series is reported, in which the decision that influenced the use of the optical coherence tomography imaging during pars plana vitrectomy is evaluated. A RESCAN 700 microscope that includes a spectral domain tomography was used to obtain the images. At the end of each procedure the surgeons completed a questionnaire to determine if the tomographic image had an influence when making decisions during the surgery, or change the decision during the procedure.

RESULTS

Thirteen patients with pars plana vitrectomy were included, with cataract surgery also performed in 6 patients. The surgeon considered that the intraoperative image influenced the decision during the procedure in 8 cases.

CONCLUSION

Intraoperative optical coherence tomography is helpful for a safe patient diagnosis. It does not affect the surgery time, and in some cases it is useful for optimising the procedure in vitreous-retinal surgery.

The Effects of 23-Gauge Pars Plana Vitrectomy on Orbital Circulation Using Doppler Ultrasonography in Diabetic Macular Edema with Epiretinal Membrane and Taut Posterior Hyaloid

PURPOSE

To evaluate using Doppler ultrasonography (DUS) how pars plana vitrectomy (PPV) affects orbital circulation in diffuse diabetic macular edema (DME) associated with either the epiretinal membrane (ERM) or taut posterior hyaloid (TPH).

METHODS

The sample included 46 eyes of 42 patients with DME associated with the ERM (n = 22, Group 1) or TPH (n = 24, Group 2). All participants received panretinal laser photocoagulation and antivascular endothelial growth factor injections preoperatively and underwent 23-gauge PPV combined with ERM or TPH removal and internal limiting membrane (ILM) peeling. Pre- and postoperative peak systolic velocity (PSV), end-diastolic velocity (EDV), and the resistivity index (RI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary artery (PCA), and central retinal vein were measured with DUS.

RESULTS

Statistically significant decreases in the PSV and EDV of the OA, CRA, and PCA were detected in all groups. In Group 1, the PSV of the OA and CRA as well as the EDV and PSV of the PCA declined significantly. In Group 2, the EDV of the OA and both the PSV and EDV of the CRA and PCA decreased. Postoperatively, the CRA's PSV and EDV were lower in Group 2, while the preoperative and postoperative RI of the CRA and preoperative RI of the PCA were greater in Group 2 than in Group 1. Changes in the CRA's RI, PSV, and EDV were greater in Group 2 after surgery.

CONCLUSIONS

23-Gauge PPV combined with ERM or TPH removal and ILM peeling in DME reduces blood flow rates of both choroidal and retinal vessels. In eyes with TPH, the RIs of the CRA and PCA were significantly greater preoperatively and the changes in the CRA's RI, PSV, and EDV were greater postoperatively. The removal of the TPH may play a role in regulating blood flow.

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.

Combined Epiretinal and Internal Limiting Membrane Peeling Facilitated by High Dilution Indocyanine Green Negative Staining

We describe the utilization of indocyanine green (ICG) dye to facilitate combined/en bloc removal of epiretinal membranes (ERM) along with internal limiting membranes (ILM). The method utilizes a highly diluted preparation of ICG in dextrose water solvent (D5W). Elimination of fluid air exchange step facilitating staining in the fluid phase and low intensity lighting help minimize potential ICG toxicity. The technique demonstrates how ICG facilitates negative staining of ERMs and how ILM peeling concomitantly can allow complete and efficient ERM removal minimizing surgical time and the necessity for dual or sequential staining.

Novel strategies for the treatment of diabetic macular edema

Macular edema such as diabetic macular edema (DME) and diabetic retinopathy are devastating back-of-the-eye retinal diseases leading to loss of vision. This area is receiving considerable medical attention. Posterior ocular diseases are challenging to treat due to complex ocular physiology and barrier properties. Major ocular barriers are static (corneal epithelium, corneal stroma, and blood-aqueous barrier) and dynamic barriers (blood-retinal barrier, conjunctival blood flow, lymph flow, and tear drainage). Moreover, metabolic barriers impede posterior ocular drug delivery and treatment. To overcome such barriers and treat back-of-the-eye diseases, several strategies have been recently developed which include vitreal drainage, laser photocoagulation and treatment with biologics and/or small molecule drugs. In this article, we have provided an overview of several emerging novel strategies including nanotechnology based drug delivery approach for posterior ocular drug delivery and treatment with an emphasis on DME.

EFFECT OF INTERNAL LIMITING MEMBRANE PEELING ON LONG-TERM VISUAL OUTCOMES FOR DIABETIC MACULAR EDEMA

PURPOSE

To evaluate the effect of internal limiting membrane (ILM) peeling on the long-term visual outcomes in eyes with diffuse, nontractional diabetic macular edema.

METHODS

One hundred and sixteen eyes of 58 patients with the same degree of diabetic macular edema in both eyes underwent pars plana vitrectomy with the creation of a posterior vitreous detachment in both eyes. Internal limiting membrane peeling was performed in one randomly selected eye (ILM-off group), and ILM peeling was not performed (ILM-on group) in the fellow eye. The postoperative follow-up period ranged from 12 months to 161 months (average, 80.4 months).

RESULTS

In the ILM-off group, the mean best-corrected visual acuity in logMAR units (Snellen equivalent) increased from 0.55 ± 0.31 (20/71) before surgery to 0.35 ± 0.35 (20/45) at 1 year (P < 0.0001) and 0.46 ± 0.43 (20/59) at the final visit (P = 0.058). In the ILM-on group, the mean best-corrected visual acuity increased from 0.55 ± 0.41 (20/71) before surgery to 0.43 ± 0.38 (20/54) at 1 year (P = 0.010) and 0.44 ± 0.45 (20/56) at the final visit (P = 0.043). The differences in the best-corrected visual acuity between the two groups were not significant at any time point.

CONCLUSION

Pars plana vitrectomy with or without ILM peeling improves the long-term visual acuity of nontractional diabetic macular edema. Internal limiting membrane peeling does not affect the postoperative best-corrected visual acuity significantly.

Pars plana vitrectomy versus three intravitreal injections of bevacizumab for nontractional diabetic macular edema. A prospective, randomized comparative study

BACKGROUND

The aim of this study was to compare the effectiveness of pars plana vitrectomy (PPV) and removal of the internal limiting membrane (ILM) with three, monthly, intravitreal bevacizumab (IVB) injections for refractory diabetic macular edema.

MATERIALS AND METHODS

This was a prospective, randomized, comparative, interventional study. Forty-four patients were enrolled and randomized in two groups. Twenty-two eyes enrolled in Group I received three IVB injections at monthly interval. Twenty-two eyes were enrolled in Group II which underwent PPV with ILM removal. The primary outcomes measured were: (1) Best corrected logMAR visual acuity (BCVA) using Snellen's visual acuity chart. (2) Central macular thickness (CMT) on optical coherence tomography. The secondary outcome measures were: Complication rates like (1) progression of lens opacities, (2) high intraocular pressure needing further treatment/procedure, (3) development of vitreous hemorrhage related to the procedure employed, (4) retinal detachment and (5) severe inflammation/endophthalmitis.

RESULTS

In Group I (IVB): 3 (13.6%) eyes showed no change in BCVA; 3 (13.6%) eyes reported decrease in BCVA and 16 (72.8%) eyes showed improvement in BCVA; (P = 0.0181). In Group II (PPV): 4 (18.2%) eyes showed no change in BCVA; 5 (22.7%) eyes showed decrease and 13 (59.1%) eyes showed improvement in BCVA (P = 0.0281). Mean decrease in CMT in IVB group was 108.45 μ, whereas mean decrease in CMT in PPV group was 161.36 μ. No major complications were seen in either group.

CONCLUSION

Posttreatment decrease in CMT was more in PPV group and vision improvement more in IVB group. However, no statistically significant difference between the two methods was found.

Macular ischemia and outcome of vitrectomy for diabetic macular edema

PURPOSE

To investigate the effect of vitrectomy on the treatment of diabetic macular edema (DME) refractory to nonsurgical therapies and to determine the preoperative prognostic factors related to surgical outcomes.

METHODS

Seventy-seven eyes from 74 patients who had undergone vitrectomy and macular photocoagulation 2 weeks after vitrectomy for nontractional DME refractory to anti-vascular endothelial growth factor or steroid injection and/or macular grid/focal photocoagulation were included. The eyes were divided into the responsive group (group 1) and the unresponsive group (group 2) according to the postoperative changes in central subfield thickness (CST). The changes in best-corrected visual acuity (BCVA) and CST were compared. Potential preoperative predictors including the size of the foveal avascular zone (FAZ) were assessed.

RESULTS

In group 1 (N = 51), the mean logarithm of the minimum angle of resolution BCVAs at baseline was 0.60 ± 0.30; 6 months after vitrectomy, 0.47 ± 0.28 (vs. baseline, p < 0.001); 12 months after vitrectomy, 0.38 ± 0.28 (vs. baseline, p < 0.001). However, in group 2 (N = 26), no significant change in BCVA was noted. Among the preoperative factors, only the size of the FAZ showed a significant difference between the two groups (0.45 ± 0.17 mm(2) in group 1 vs. 0.59 ± 0.26 mm(2) in group 2; p = 0.020). The enlarged FAZ was also significantly correlated with worse BCVA at the postoperative 6-month follow-up (r = 0.256, p = 0.025).

CONCLUSIONS

Vitrectomy is an effective treatment modality for DME refractory to nonsurgical therapies, especially in cases without enlarged FAZ. Preoperative evaluation of the perfusion status of the macula seems helpful to selecting candidates for vitrectomy.

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.

Evolving strategies in the management of diabetic retinopathy

Diabetic retinopathy (DR), the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Tight glycemic and blood pressure control has been shown to significantly decrease the risk of development as well as the progression of retinopathy and represents the cornerstone of medical management of DR. The two most threatening complications of DR are diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Focal/grid photocoagulation and panretinal photocoagulation are standard treatments for both DME and PDR, respectively. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with DME. Currently, most experts consider combination focal/grid laser therapy and pharmacotherapy with intravitreal antivascular endothelial growth factor agents in patients with center-involving DME. Combination therapy reduces the frequency of injections needed to control edema. Vitrectomy with removal of the posterior hyaloid seems to be effective in eyes with persistent diffuse DME, particularly in eyes with associated vitreomacular traction. Emerging therapies include fenofibrate, ruboxistaurin, renin-angiotensin system blockers, peroxisome proliferator-activated receptor gamma agonists, pharmacologic vitreolysis, and islet cell transplantation.

Treatment options for diffuse diabetic macular edema

PURPOSE

To describe the current management of diffuse diabetic macular edema (DDME).

METHODS

Review and discussion of the literature regarding DDME.

RESULTS

Diffuse diabetic macular edema is a condition that can be managed by means of several treatment options, including focal/grid laser photocoagulation, intravitreal or periocular corticosteroids, intravitreal anti-vascular endothelial growth factor (VEGF), and vitrectomy with or without internal limiting membrane peeling.

CONCLUSIONS

Even though there is no randomized clinical trial specifically designed to assess the best treatment approach for DDME, new therapeutic approaches based on intravitreal injections of corticosteroid and anti-VEGF molecules offer new hope for its management.

Vitrectomy combined with intravitreal triamcinolone acetonide injection and macular laser photocoagulation for nontractional diabetic macular edema

Purpose

To evaluate the efficacy of vitrectomy combined with intravitreal injection of triamcinolone acetonide (IVTA) and macular laser photocoagulation for the treatment of nontractional diabetic macular edema (DME) refractory to anti-vascular endothelial growth factor (VEGF) therapy.

Methods

Twenty-eight eyes from 28 subjects who were diagnosed with nontractional DME refractory to three or more sequential anti-VEGF injections underwent sequential vitrectomy, IVTA, and macular laser photocoagulation. Changes in best-corrected visual acuity (BCVA) and central subfield thickness (CST) during the six months following vitrectomy were evaluated. Additionally, the CST and BCVA outcomes were compared with those of 26 eyes treated with the same triple therapy for nontractional DME refractory to conventional treatment, such as IVTA or macular laser photocoagulation, or both.

Results

The mean logarithm of the minimum angle of resolution BCVAs before and one, three, and six months after vitrectomy were 0.44 ± 0.15, 0.36 ± 0.18, 0.31 ± 0.14, and 0.34 ± 0.22, respectively. The mean CSTs were 433.3 ± 77.9, 329.9 ± 59.4, 307.2 ± 60.2, and 310.1 ± 80.1 microns, respectively. The values of both BCVA and CST at one, three, and six months were significantly improved from baseline (p < 0.05). The extent of CST reduction during the first month after triple therapy was greater in eyes refractory to conventional treatment than in eyes refractory to anti-VEGF (p = 0.012).

Conclusions

Vitrectomy combined with IVTA and macular laser photocoagulation had a beneficial effect on both anatomical and functional outcomes in eyes with nontractional DME refractory to anti-VEGF therapy.

Combined vitrectomy and intravitreal injection versus combined laser and injection for treatment of intractable diffuse diabetic macular edema

BACKGROUND

The purpose of this study was to compare the safety and efficacy of combined vitrectomy, intravitreal triamcinolone acetonide (IVTA), and bevacizumab injection with that of IVTA and bevacizumab injection and subsequent macular grid laser photocoagulation for the treatment of intractable diffuse diabetic macular edema.

METHODS

This randomized controlled clinical trial was performed at Benha University Hospital, Benha, Egypt, and included 34 eyes from 34 diabetic patients diagnosed with intractable diffuse diabetic macular edema without vitreomacular traction. The patients were divided into two groups. In group 1, pars plana vitrectomy with removal of the posterior hyaloid was performed, and at the end of the procedure, IVTA 0.1 mL (40 mg/mL) and bevacizumab 1.25 mg were injected. In group 2, macular grid laser photocoagulation was performed 2 weeks after the same intravitreal injection combination as used in group 1. The main outcome measures were best-corrected visual acuity (BCVA) and central foveal thickness, which were measured using optical coherence tomography at 3, 6, and 12 months.

RESULTS

Changes in BCVA and central foveal thickness at 3, 6, and 12 months from baseline were highly statistically significant (P < 0.01). Mean BCVA was better in group 1 at 3 months, nearly equal at 6 months, and less at 12 months. Mean central foveal thickness was more improved in group 1 than in group 2 at 3 months, and was better in group 2 at subsequent measurement points. The major adverse events were development of cataract (more common in group 1) and elevation of intraocular pressure (more common in group 2).

CONCLUSION

The combined therapy described here could represent a solution for the treatment of intractable diabetic macular edema, and could have a favorable long-term outcome. Combined treatment of IVTA and bevacizumab plus grid laser resulted in a more favorable reduction in central foveal thickness and improvement in BCVA at 12 months than vitrectomy combined with the same injections. This small study favors the safer, cheaper, and more available line of treatment.

Diabetic macular edema: new trends in management

The treatment of diabetic macular edema may be evolving from a laser ablative approach into a pharmacotherapeutic approach. The exponential growth that has occurred over the past decade in the retinal pharmacotherapy field has led to the development of several pharmacotherapies for retinal vascular diseases such as diabetic macular edema. Many of these agents, in the form of intravitreal injections or sustained delivery devices, have already undergone clinical trial testing for safety and efficacy and many others are currently being similarly evaluated. Some of these agents have proven to be more efficacious than traditional laser therapy, and it is possible that traditional laser therapy for diabetic macular edema may be abandoned altogether in the near future, especially with the introduction of the micropulse laser. However, more research and experience is still needed in order to determine the best treatment agent or combination of therapeutic modalities, as well as the best treatment regimen for a given patient. In this article, we briefly review the major new developments in the field of diabetic macular edema treatment. In addition, we touch on some of the promising forthcoming therapies.

Techniques, rationale, and outcomes of internal limiting membrane peeling

BACKGROUND

The internal limiting membrane represents the structural interface between the retina and the vitreous and has been postulated to serve several essential functions. Recently, internal limiting membrane peeling has been used in the treatment of a variety of retinal disorders. We review the history, techniques, rationale, and outcomes of internal limiting membrane peeling.

METHODS

A review of the literature.

RESULTS

Internal limiting membrane peeling has been used to successfully treat a variety of retinal disorders including macular hole, epiretinal membrane, diabetic macular edema, retinal vein occlusion, and others.

CONCLUSION

Internal limiting membrane peeling may serve as an important component in the armamentarium of retinal surgery.

Evidence for diffuse central retinal edema in vivo in diabetic male Sprague Dawley rats

Background

Investigations into the mechanism of diffuse retinal edema in diabetic subjects have been limited by a lack of animal models and techniques that co-localized retinal thickness and hydration in vivo. In this study we test the hypothesis that a previously reported supernormal central retinal thickness on MRI measured in experimental diabetic retinopathy in vivo represents a persistent and diffuse edema.

Methodology/Principal Findings

In diabetic and age-matched control rats, and in rats experiencing dilutional hyponatremia (as a positive edema control), whole central retinal thickness, intraretinal water content and apparent diffusion coefficients (ADC, ‘water mobility’) were measured in vivo using quantitative MRI methods. Glycated hemoglobin and retinal thickness ex vivo (histology) were also measured in control and diabetic groups. In the dilutional hyponatremia model, central retinal thickness and water content were supernormal by quantitative MRI, and intraretinal water mobility profiles changed in a manner consistent with intracellular edema. Groups of diabetic (2, 3, 4, 6, and 9 mo of diabetes), and age-matched controls were then investigated with MRI and all diabetic rats showed supernormal whole central retinal thickness. In a separate study in 4 mo diabetic rats (and controls), MRI retinal thickness and water content metrics were significantly greater than normal, and ADC was subnormal in the outer retina; the increase in retinal thickness was not detected histologically on sections of fixed and dehydrated retinas from these rats.

Conclusions/Significance

Diabetic male Sprague Dawley rats demonstrate a persistent and diffuse retinal edema in vivo, providing, for the first time, an important model for investigating its pathogenesis and treatment. These studies also validate MRI as a powerful approach for investigating mechanisms of diabetic retinal edema in future experimental and clinical investigations.

Diabetic retinopathy - An update

Management of diabetes should involve both systemic and ocular aspects. Control of hyperglycemia, hypertension and dyslipidemia are of major role in the management of diabetic retinopathy. In the ocular part; laser treatment remains the cornerstone of treatment of diabetic macular edema (focal/grid), severe non-proliferative and proliferative diabetic retinopathy (panretinal photocoagulation). There is a strong support to combination therapy. Using one or two intravitreal injections such as anti-VEGF and or steroid to reduce central macular thickness followed by focal or grid laser to give a sustained response may offer an alternative to treatment in diabetic macular edema. Anti-VEGF were found to be effective as an adjunct therapy in proliferative diabetic retinopathy patient who is going to have vitrectomy for vitreous hemorrhage with neovascularization, panretinal photocoagulation, and other ocular surgery such as cases with neovascular glaucoma and cataract with refractory macular edema.