For people receiving regular eye injections for neovascular macular degeneration, the growth of scar tissue in the retina remains a serious concern. A major review of 58 studies found that this scarring, called subretinal fibrosis, developed in roughly 10-15% of treated eyes within two years, and in 40-50% by five years. Eyes that developed this scarring had vision that was, on average, about 29 letters worse on a standard eye chart than eyes without it.
The research also looked at what might be linked to a higher risk of scarring. Eyes with certain features at the start of treatment—like a specific type of abnormal blood vessel growth or certain types of fluid or bleeding—had higher odds of developing fibrosis. Interestingly, a different type of fluid under the retina was linked to lower odds. The analysis also suggested that eyes on a more regular injection schedule (fixed or treat-and-extend) might have a lower incidence of scarring than those treated only as needed.
It's crucial to understand what this review can and cannot tell us. The findings show associations, not proof of cause and effect. A major limitation is that the studies used widely different methods to define and measure scarring on eye scans, making it hard to compare results precisely. This means the reported percentages should be seen as a range, not a precise prediction. The work clearly shows that scarring is a common and vision-harming complication, underscoring the need for better, standardized ways to define it in future research.