The Evolving Standard of Care in Diabetic Retinal Disease

For decades, advanced diabetic retinopathy has been synonymous with a high risk of vision loss and, all too often, the need for vitrectomy surgery. This invasive procedure, in which the vitreous gel is removed from the eye, can stabilize vision but carries inherent risks and requires significant recovery time. Yet a paradigm shift is underway. The growing use of dual therapy—combining pharmacological agents with focal laser or other minimally invasive interventions—is fundamentally changing the treatment landscape. Early evidence suggests that this approach can dramatically reduce the need for vitrectomy, offering patients a less invasive path to preserving sight. Understanding why this matters requires a closer look at the disease itself, the limitations of traditional treatment, and the science behind these new combination strategies.

What Is Diabetic Retinal Disease?

Diabetic retinal disease, commonly called diabetic retinopathy (DR), is the leading cause of preventable blindness among working-age adults in developed nations. It arises as a microvascular complication of diabetes mellitus—both type 1 and type 2. Chronic hyperglycemia triggers a cascade of metabolic derangements: oxidative stress, accumulation of advanced glycation end products, and upregulation of inflammatory mediators. These insults damage the endothelial lining of retinal capillaries, leading to pericyte loss, capillary basement membrane thickening, and eventual breakdown of the blood-retinal barrier.

Phases of Diabetic Retinopathy

The disease follows a predictable progression. In the early stage, non-proliferative diabetic retinopathy (NPDR), patients may be asymptomatic. Fundoscopic examination reveals microaneurysms, dot-and-blot hemorrhages, and hard exudates. As NPDR worsens, venous beading and intraretinal microvascular abnormalities (IRMA) appear. Without intervention, the disease transitions to proliferative diabetic retinopathy (PDR), characterized by retinal neovascularization. These new blood vessels are fragile and prone to leakage, leading to vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma—the very complications that often necessitate vitrectomy.

Epidemiology and Risk Factors

Globally, an estimated 103 million people have diabetic retinopathy, with roughly one-third of those living with diabetes developing some form of retinal involvement during their lifetime. Duration of diabetes is the single strongest risk factor: after 20 years, nearly all patients with type 1 diabetes and more than 60% of those with type 2 diabetes have some degree of retinopathy. Additional risk factors include poor glycemic control, hypertension, dyslipidemia, pregnancy, and nephropathy. The rising prevalence of type 2 diabetes, particularly in younger populations, underscores the urgency of developing effective, less invasive treatments.

The Role of Vitrectomy in Advanced Disease

Vitrectomy has historically been the mainstay intervention for advanced proliferative diabetic retinopathy, especially when vitreous hemorrhage fails to clear spontaneously or when tractional retinal detachment threatens the macula. The procedure involves creating small incisions in the sclera, inserting a vitrector to remove the vitreous gel, and then addressing the underlying pathology—for example, removing blood, cutting tractional bands, and performing endolaser photocoagulation.

When Is Vitrectomy Necessary?

Indications for vitrectomy in diabetic eye disease include:

  • Non-clearing vitreous hemorrhage (typically after 1–3 months of observation)
  • Tractional retinal detachment, especially if the macula is involved or at imminent risk
  • Combined tractional and rhegmatogenous retinal detachment
  • Severe recurrent vitreous hemorrhage despite adequate laser and anti-VEGF therapy
  • Dense premacular hemorrhage that impairs vision

While effective, vitrectomy is not without risks. Procedural complications include iatrogenic retinal tears, endophthalmitis, cataract formation (especially accelerated after pars plana vitrectomy in older patients), postoperative intraocular pressure spikes, and cystoid macular edema. Recovery can be prolonged, and patients often require face-down positioning for days to weeks. Even with successful anatomic outcomes, visual recovery may be incomplete due to underlying retinal ischemia or foveal damage. Thus, any strategy that can safely defer or eliminate the need for vitrectomy represents a major clinical advance.

Dual Therapy: A Synergistic Approach

The term dual therapy in diabetic retinal disease generally refers to the combined use of anti-vascular endothelial growth factor (anti-VEGF) injections with laser photocoagulation (most commonly focal/grid laser or panretinal photocoagulation [PRP]). In some cases, corticosteroid implants or injections are also paired with laser. The rationale is that each modality targets a different aspect of the disease pathology, creating a synergistic effect that is more powerful than either treatment alone.

Component 1: Anti-VEGF Agents

VEGF is the primary driver of neovascularization and vascular permeability in diabetic retinopathy. Anti-VEGF drugs such as ranibizumab (Lucentis), aflibercept (Eylea), and the recently developed faricimab (Vabysmo) bind to VEGF isoforms and inhibit their activity. These agents have transformed the management of diabetic macular edema (DME) and are now also first-line for proliferative disease. Intravitreal injections are performed in-clinic under topical anesthesia. Anti-VEGF therapy rapidly regresses retinal neovascularization, reduces vitreous hemorrhage, and improves macular edema, often leading to significant visual gains. However, the effect is temporary, requiring repeated injections at intervals of 4 to 16 weeks depending on the drug and disease activity.

Component 2: Laser Photocoagulation

Laser therapy has been the cornerstone of diabetic retinopathy treatment for over 40 years. Two main types are used:

  • Focal/grid laser: Applied to areas of macular edema, directly sealing leaking microaneurysms and treating diffuse capillary leakage. This reduces edema and improves central vision.
  • Panretinal photocoagulation (PRP): Applied to the peripheral retina in a scatter pattern, PRP destroys ischemic retina, reducing the stimulus for VEGF production and thereby inducing regression of neovascularization. PRP has been proven to reduce the risk of severe vision loss from proliferative disease by approximately 50%.

While laser is highly effective, it can cause collateral damage: PRP may lead to constriction of the visual field, night vision difficulties, and exacerbation of macular edema in some patients. Focal/grid laser, when used aggressively, can produce scotomas. The combination of anti-VEGF and laser is designed to minimize the amount of laser needed (and thus its side effects) while still achieving durable disease control.

Clinical Evidence Supporting Dual Therapy

Several landmark clinical trials have evaluated the efficacy of combining anti-VEGF with laser versus laser monotherapy or anti-VEGF monotherapy. The results consistently favor combination approaches in specific clinical scenarios.

The Diabetic Retinopathy Clinical Research Network (DRCR.net) Protocol I

Protocol I compared ranibizumab plus prompt or deferred focal/grid laser against laser alone for DME. At one year, the combination groups showed significantly better visual acuity gains and greater reduction in retinal thickness. The deferred laser arm (ranibizumab alone with laser added only if needed) performed especially well, suggesting that anti-VEGF could reduce the need for immediate laser while still providing excellent outcomes. Critically, the need for vitrectomy was lower in the anti-VEGF-treated groups compared to the history of patients treated with laser alone.

Protocol S: PRP vs. Ranibizumab for PDR

In patients with proliferative diabetic retinopathy, DRCR.net Protocol S directly compared PRP with ranibizumab (0.5 mg) as the primary treatment. The study found that at two years, visual acuity outcomes were non-inferior for ranibizumab compared to PRP, and the anti-VEGF group had fewer occurrences of vitreous hemorrhage and a lower need for vitrectomy. However, ranibizumab required more frequent injections (six to nine in the first year), and many patients eventually needed some PRP. The concept of initial anti-VEGF therapy with deferred PRP emerged as a viable dual-therapy strategy that could reduce the long-term burden of laser and, in many cases, avoid vitrectomy altogether.

Real-World Evidence and Combination Protocols

Observational studies and case series from high-volume retina centers reinforce these findings. A 2022 meta-analysis of nine randomized trials reported that patients receiving anti-VEGF in combination with laser had a 40% lower risk of requiring vitrectomy over a follow-up of two to five years compared with those receiving laser alone. The benefit was most pronounced in patients with high-risk proliferative disease and those presenting with active vitreous hemorrhage. Dual therapy also appeared to reduce the incidence of tractional retinal detachment, likely by more effectively regressing neovascular tissue.

Mechanisms: Why Dual Therapy Works

The synergy between anti-VEGF and laser is not merely additive. Anti-VEGF injections rapidly lower intraocular VEGF levels, leading to prompt regression of fragile new vessels. This reduces the risk of bleeding and allows any existing hemorrhage to clear more quickly. Laser, on the other hand, provides a more durable reduction in VEGF by permanently ablating ischemic retina that would otherwise continue to produce the growth factor. The combination thus offers short-term control (anti-VEGF) with long-term stability (laser).

Furthermore, dual therapy may have anti-inflammatory benefits beyond VEGF inhibition. Some trials include adjunctive intravitreal steroids (such as dexamethasone implant or triamcinolone acetonide) for patients with persistent DME despite anti-VEGF and laser. Corticosteroids block multiple inflammatory pathways, reduce leukostasis, and stabilize the blood-retinal barrier. While steroid use carries risks of cataract and glaucoma, it can be a valuable third component in select patients with refractory disease.

Who Benefits Most from Dual Therapy?

Not every patient with diabetic retinopathy needs dual therapy. But for those at highest risk of progression to vitrectomy, it is a critical tool. Ideal candidates include:

  • Patients with active proliferative disease and at least moderate vitreous hemorrhage
  • Those with high-risk PDR (neovascularization of the disc or retina with vitreous hemorrhage)
  • Patients with concurrent DME that might be exacerbated by PRP alone
  • Individuals who cannot tolerate the side effects of extensive laser (e.g., those with existing visual field deficits)
  • Patients with poor glycemic control who are at high risk of rapid disease progression

Importantly, early initiation of dual therapy appears to be key. Retina specialists are moving toward treating proliferative disease as soon as neovascularization is detected, rather than waiting for hemorrhagic complications. This "treat early" philosophy aims to arrest the disease before irreversible damage occurs, further reducing the likelihood of vitrectomy.

Reducing the Need for Vitrectomy: The Numbers

Quantifying how much dual therapy reduces vitrectomy rates is complex because baseline rates vary widely by population, access to care, and era. However, data from large registries provide compelling estimates. In the United States, the rate of vitrectomy for diabetic retinopathy declined by approximately 30% between 2008 and 2018, coinciding with the widespread adoption of anti-VEGF therapy. In centers that aggressively adopt dual-therapy protocols, vitrectomy rates for PDR have dropped to as low as 5–10% over two years, compared to historical rates of 20–30% with PRP alone.

Even when vitrectomy cannot be entirely avoided, dual therapy may convert an urgent, high-risk case into a more elective, safer procedure. Preoperative anti-VEGF injections reduce intraoperative bleeding, facilitate membrane peeling, and improve surgical outcomes. Many surgeons now routinely inject anti-VEGF 3–7 days before vitrectomy for PDR, a practice supported by randomized trials showing fewer intraoperative complications and better early visual recovery.

Practical Considerations in Implementing Dual Therapy

Adopting a dual-therapy approach requires careful coordination. The typical regimen begins with a loading dose of three to six monthly anti-VEGF injections. After the first or second injection, the retina specialist evaluates whether residual neovascularization or macular edema is present. If significant disease persists, focal/grid laser or limited PRP is applied. Over the subsequent months, the injection interval is extended (e.g., treat-and-extend protocol) while monitoring for regression of neovascularization and stability of macular thickness.

Laser is not always needed in the first few months. Some patients respond so well to anti-VEGF alone that they can be maintained with injections only, with laser reserved for breakthrough activity. This "anti-VEGF first, laser as needed" strategy is now common and has been validated by Protocol S findings. However, long-term compliance with regular injections is essential; patients lost to follow-up may experience rapid recurrence of neovascularization and vitreous hemorrhage.

Challenges and Limitations

Dual therapy is not a panacea. Some patients still progress to vitrectomy despite optimal medical and laser treatment. Factors associated with treatment failure include extreme ischemia leading to high VEGF levels, poor glycemic control, noncompliance with injections, and the presence of extensive fibrovascular proliferation. Moreover, dual therapy does not address the underlying metabolic derangements of diabetes; systemic control remains paramount. Ophthalmologists must work in tandem with primary care providers and endocrinologists to optimize blood glucose, blood pressure, and lipid management.

Cost and access are also barriers. Anti-VEGF drugs are expensive, especially newer agents like faricimab. In healthcare systems with limited resources, frequent injections may not be feasible, and laser remains the backbone of treatment. Additionally, many patients require bilateral treatment, further escalating cost. Research into longer-acting agents and sustained-delivery systems is ongoing and may improve affordability in the future.

Future Directions: Next-Generation Dual Therapy

The concept of dual therapy continues to evolve. Newer drug classes, including angiopoietin-2 inhibitors (already incorporated into faricimab), offer additional anti-inflammatory and anti-permeability effects. Combination devices, such as the Port Delivery System with ranibizumab, aim to reduce injection frequency while maintaining continuous intraocular drug levels. Trials are investigating whether these technologies, combined with targeted laser, can further reduce vitrectomy rates.

Furthermore, imaging advances like ultra-widefield fluorescein angiography and optical coherence tomography angiography allow clinicians to identify areas of ischemia and neovascularization earlier and more precisely. This enables personalized dual therapy: laser is applied only to the most active regions, sparing more healthy retina and minimizing side effects. Machine learning algorithms are being developed to predict which patients will respond best to dual therapy versus those who may still require early surgery.

Conclusion: A Less Invasive Path Forward

The evidence is clear: dual therapy combining anti-VEGF agents with laser photocoagulation significantly reduces the need for vitrectomy in diabetic retinal disease. By attacking the disease from two complementary angles—pharmacologic blockade of VEGF and permanent reduction of ischemic retina—this approach offers patients a powerful, less invasive alternative to traditional management. Visual outcomes improve, complications are minimized, and the trajectory of vision loss can be altered. For clinicians, the challenge is to identify candidates early, implement dual therapy proactively, and coordinate systemic care. For patients, the promise is a future in which the once-feared vitrectomy becomes an increasingly rare event. Continued innovation and wider access to these combined treatments will be essential to preserving the sight of millions worldwide living with diabetic retinopathy.

References and Further Reading

  • Diabetic Retinopathy Clinical Research Network. Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema. Ophthalmology. 2010;117(6):1064-1077.e35. PubMed
  • Diabetic Retinopathy Clinical Research Network. Panretinal photocoagulation vs intravitreous ranibizumab for proliferative diabetic retinopathy: a randomized clinical trial. JAMA. 2015;314(20):2137-46. PubMed
  • American Academy of Ophthalmology. Preferred Practice Pattern: Diabetic Retinopathy. 2023. AAO
  • National Eye Institute. Facts About Diabetic Eye Disease. NEI
  • Sun JK, Jampol LM. The Diabetic Retinopathy Clinical Research Network (DRCR.net): its history, progress, and future. Asia Pac J Ophthalmol (Phila). 2017;6(6):545-553. PubMed