This study, conducted by the Comparison of Age-related Macular Degeneration Treatments Trials (CATT) Research Group, aimed to compare the effects of ranibizumab and bevacizumab in treating neovascular age-related macular degeneration (AMD) over a two-year period. The trial involved 1185 patients, with 1107 patients followed for the full duration. Patients were initially assigned to four treatment groups based on drug (ranibizumab or bevacizumab) and dosing regimen (monthly or as needed). After one year, patients initially on monthly treatment were randomly reassigned to either monthly or as-needed treatment. The primary outcome measure was the mean change in visual acuity. Results showed that both drugs had similar effects on visual acuity over two years, with a mean gain of 8.8 letters for ranibizumab-monthly and 7.8 letters for bevacizumab-monthly. The difference in mean improvement between the two drugs was minimal, with bevacizumab showing a slight advantage. However, the mean gain was greater for monthly treatment compared to as-needed treatment. Switching from monthly to as-needed treatment after one year resulted in a greater decrease in visual acuity and a lower proportion of patients without fluid. Rates of death and arteriothrombotic events were similar for both drugs, but bevacizumab had a higher rate of serious adverse events, particularly gastrointestinal disorders. The study concluded that both ranibizumab and bevacizumab are effective in treating AMD, with similar visual outcomes over two years. However, the choice between the two drugs and dosing regimens should consider the balance of benefits and risks, including the high cost of ranibizumab.This study, conducted by the Comparison of Age-related Macular Degeneration Treatments Trials (CATT) Research Group, aimed to compare the effects of ranibizumab and bevacizumab in treating neovascular age-related macular degeneration (AMD) over a two-year period. The trial involved 1185 patients, with 1107 patients followed for the full duration. Patients were initially assigned to four treatment groups based on drug (ranibizumab or bevacizumab) and dosing regimen (monthly or as needed). After one year, patients initially on monthly treatment were randomly reassigned to either monthly or as-needed treatment. The primary outcome measure was the mean change in visual acuity. Results showed that both drugs had similar effects on visual acuity over two years, with a mean gain of 8.8 letters for ranibizumab-monthly and 7.8 letters for bevacizumab-monthly. The difference in mean improvement between the two drugs was minimal, with bevacizumab showing a slight advantage. However, the mean gain was greater for monthly treatment compared to as-needed treatment. Switching from monthly to as-needed treatment after one year resulted in a greater decrease in visual acuity and a lower proportion of patients without fluid. Rates of death and arteriothrombotic events were similar for both drugs, but bevacizumab had a higher rate of serious adverse events, particularly gastrointestinal disorders. The study concluded that both ranibizumab and bevacizumab are effective in treating AMD, with similar visual outcomes over two years. However, the choice between the two drugs and dosing regimens should consider the balance of benefits and risks, including the high cost of ranibizumab.