The duration of treatment for age-related macular degeneration (AMD) with injections varies significantly from person to person. These injections treat the “wet” or neovascular form of AMD, which causes the majority of severe vision loss. In wet AMD, abnormal blood vessels grow beneath the macula, the central part of the retina, causing them to leak fluid and blood. This leakage rapidly damages the light-sensing tissue, leading to distorted or lost central vision. Standard therapy involves intravitreal injections of anti-Vascular Endothelial Growth Factor (anti-VEGF) medications, which block the protein that stimulates the growth and leakage of these vessels. This treatment is highly effective at stabilizing vision and requires a long-term commitment.
The Initial Loading Dose Period
Treatment for wet AMD begins with the loading dose period, a fixed-duration phase. This initial phase typically involves three to four consecutive monthly injections, administered approximately four weeks apart. This consistent, high-frequency dosing is designed to achieve maximum saturation of the medication. The primary goal of this loading phase is to quickly suppress the activity of the abnormal blood vessels. By achieving maximal drug effect, the ophthalmologist aims to completely dry up the fluid beneath and within the retina, which signals disease activity.
Understanding Variable Treatment Protocols
Once the initial loading phase is complete and the retina has stabilized, the duration and frequency of subsequent injections become personalized and variable. Ophthalmologists commonly employ one of two primary strategies to manage the long-term course of the disease.
Treat-and-Extend (T&E)
The most common approach is the “Treat-and-Extend” (T&E) protocol, which addresses the chronic nature of wet AMD. Under this protocol, patients receive an injection at every visit, and the time interval between appointments is progressively lengthened as long as the retina remains stable. The interval might start at six weeks and be extended by two weeks at a time, potentially reaching up to 12 weeks between injections. If signs of fluid return, the interval is immediately shortened to regain control of the disease activity.
Pro Re Nata (PRN)
A less common strategy is the “Pro Re Nata” (PRN), or “treatment as needed,” protocol. Injections are only given if the doctor detects a recurrence of fluid during a monthly check-up. Studies show that the T&E protocol results in better visual outcomes and fewer fluctuations in vision compared to the PRN approach, even though it requires a higher total number of injections. The choice of protocol determines the ongoing treatment timeline, which can span many years.
Clinical Factors Determining Duration
The decision to maintain, shorten, or extend the time between injections is based entirely on specific clinical data collected during each patient visit. The most important tool for this assessment is the Optical Coherence Tomography (OCT) scan, which provides a detailed, cross-sectional image of the retina. The presence or absence of intraretinal or subretinal fluid on the OCT is the strongest indicator of whether the disease is active and whether the injection interval needs adjustment. If the retina is completely dry, the doctor may choose to extend the time until the next injection.
Other factors influencing the treatment duration include changes in the patient’s visual acuity, measured by the number of letters they can read on an eye chart. A decrease of five or more letters may signal disease reactivation, necessitating an immediate injection and a shorter subsequent interval. The development of subretinal scarring, known as fibrosis, can also impact the decision-making process. Significant scarring may lead the doctor to consider stopping injections, as the potential for vision recovery is limited once the tissue has been replaced by scar tissue.
Monitoring After Injection Frequency Decreases
Even when a patient has achieved a long interval, or the doctor has paused active treatment, ongoing monitoring is still necessary due to the chronic nature of the disease. The risk of recurrence persists indefinitely. Regular check-ups with the ophthalmologist, including visual acuity testing and OCT scanning, are required even if no injection is given. This frequent clinical assessment helps ensure that any return of fluid is caught and treated quickly before it can cause permanent damage.
Patients also play a role in their own long-term monitoring by routinely using an Amsler grid at home. This simple grid test helps detect subtle changes in central vision, such as new distortion or blank spots, which can be the first sign of fluid leakage. For some individuals, treatment may be lifelong, requiring injections several times a year to maintain vision. While some patients may achieve a prolonged treatment pause, the commitment to regular monitoring never ends.