From your letter, it sounds like you have been referred to the 'surveillance' branch of the eye screening service. This means that there are some changes in the eye which are not severe enough to warrant referral to the hospital eye service but need to be monitored in case the changes progress. Many people are referred to surveillance, are monitored there a few times and then put back into annual screening when the changes that were detected clear up. For some people, the changes progress and they will need to be referred to the hospital eye service for further testing in order to see whether the changes are significant and require treatment. The more frequent monitoring in the surveillance service means that any significant changes that require treatment are picked up at an early stage when the treatment is most effective.
The best way to prevent progression of maculopathy is to maintain good control of blood glucose, blood pressure and lipids.