After one year, 27 percent of patients in the 1 milligram group and 26 percent of patients in the 4 milligram group experienced a substantial visual gain of three or more lines on a vision chart-equivalent to identifying letters that were half as small as they could read before treatment. Only 7 percent of patients in the observation group experienced a similar visual gain. Therefore, patients in the corticosteroid treatment groups were five times more likely to have a substantial visual gain at one year. These results appeared to last up to two years, though the two-year results included a smaller number of patients.
How often cortisone injections are given varies based on the reason for the injection. This is determined on a case-by-case basis by the health care practitioner. If a single cortisone injection is curative, then further injections are unnecessary. Sometimes, a series of injections might be necessary; for example, cortisone injections for a trigger finger may be given every three weeks, to a maximum of three times in one affected finger. In other instances, such as knee osteoarthritis, a second cortisone injection may be given approximately three months after the first injection, but the injections are not generally continued on a regular basis.