Diabetic retinopathy (DR) is a long-term complication of diabetes that damages the small blood vessels within the retina. High blood sugar levels weaken vessel walls, causing them to leak fluid or blood. This leakage often causes diabetic macular edema (DME), where the macula swells, leading to blurred central vision.
In advanced stages, oxygen deprivation triggers the growth of new, fragile, and abnormal blood vessels (proliferative diabetic retinopathy, or PDR). These vessels can bleed easily or form scar tissue that pulls on the retina, causing severe vision loss. Medical treatments aim to halt damage progression, reduce swelling, and shrink abnormal vessels.
Anti-VEGF Agents The Primary Treatment
Anti-Vascular Endothelial Growth Factor (VEGF) agents target VEGF, a protein released by the oxygen-starved retina. VEGF signals the growth of new, leaky blood vessels and increases the permeability of existing ones. Anti-VEGF therapy blocks this signaling pathway, reducing leakage and fluid accumulation in DME, and suppressing abnormal vessel growth in PDR.
These agents are administered via intravitreal injection directly into the vitreous humor, ensuring the medication reaches the retina in high concentration. Commonly used agents include Ranibizumab, Aflibercept, and Bevacizumab (often used off-label due to its cost-effectiveness).
For diabetic macular edema, anti-VEGF therapy is the first-line standard of care. Treatment typically starts with a loading phase of monthly injections until the fluid decreases. Frequency is then adjusted using a treat-and-extend protocol, where the interval between injections is gradually lengthened. Consistent treatment is necessary because the drug effect lasts only a few weeks before VEGF levels rise again.
Anti-VEGF agents are also a standard treatment for proliferative diabetic retinopathy, shrinking the newly formed, fragile blood vessels. This pharmacological approach can be as effective as traditional laser therapy for PDR, often resulting in better visual outcomes. Pre-operative anti-VEGF injections can stabilize abnormal vessels before surgery for advanced PDR complications, reducing bleeding risk.
Diabetic retinopathy is a chronic condition requiring long-term management. While acute symptoms may resolve, the underlying damage persists, necessitating ongoing monitoring and repeated injections over several years. Treatment success relies heavily on consistent patient compliance with the demanding injection schedule.
Corticosteroid Injections and Implants
Corticosteroids address the inflammatory components of diabetic macular edema (DME). They suppress inflammation and stabilize leaky blood vessels, making them suitable when DME does not respond adequately to anti-VEGF therapy or when anti-VEGF agents are not preferred.
Corticosteroids are delivered via intravitreal injection, often as slow-release implants that provide a sustained therapeutic effect and reduce treatment frequency.
Types of Implants
The Dexamethasone implant is biodegradable and releases medication over four to six months.
The Fluocinolone Acetonide implant releases a low dose for up to three years, reducing the treatment burden for chronic DME.
The sustained release is beneficial for patients who struggle with frequent injection schedules. However, corticosteroids carry a higher risk of specific ocular side effects compared to anti-VEGF drugs. A common side effect is elevated intraocular pressure, which may require pressure-lowering eye drops or surgical management. Cataract formation or progression is another frequent complication, especially with longer-acting implants. Corticosteroids are often favored in patients who have already had cataract surgery (pseudophakic eyes), as the risk of cataract development is eliminated.
Surgical and Laser Treatment Options
Laser and surgical procedures remain important interventions for advanced or non-responsive stages of diabetic retinopathy. Laser treatment, known as photocoagulation, uses focused light energy to treat the damaged retina.
Panretinal Photocoagulation (PRP)
PRP is utilized for proliferative diabetic retinopathy (PDR) with widespread abnormal vessel growth. It involves applying hundreds of small laser burns to the peripheral retina. This reduces the retina’s overall oxygen demand, subsequently lowering VEGF production. This causes the abnormal new vessels to shrink and regress. While effective at preventing severe vision loss from PDR, PRP can result in some loss of peripheral, night, and color vision.
Focal or Grid Laser Treatment
Focal or Grid laser treatment is aimed specifically at managing diabetic macular edema. This technique involves applying precise, low-intensity laser spots to specific areas of leakage near the macula. The laser creates tiny scars that help seal off the leaking microaneurysms, reducing fluid accumulation and stabilizing the retinal tissue.
Vitrectomy
In the most advanced cases of diabetic retinopathy, surgical intervention via a vitrectomy may be necessary. This procedure involves removing the vitreous humor from the center of the eye, which is often clouded by a vitreous hemorrhage (bleeding from abnormal vessels). Vitrectomy also allows the surgeon to peel away scar tissue that is pulling on the retina, a condition known as tractional retinal detachment.