One hypothesis for IRU is that there may still be low level CMV replication in the eye. The newly invigorated immune response may be attacking the CMV and causing inflammation. There are several unknowns at this point. It is not known if people who have the ganciclovir implants (Vitrasert®) to treat CMV are as likely to develop IRU because the implants are better able to control CMV replication. It is also not known if IRU will improve if someone resumes CMV therapies.
Ophthalmologists have tried a few different therapies to treat IRU with limited success, including systemic prednisone, periocular (around the eye) injections of prednisone and methylprednisolone (Depo-Medrol®). In most instances, when these medications were stopped, the IRU returned.
A large observational study has started at the Studies of Ocular Complications from AIDS (SOCA) sites and it is hoped that this study will be able to assess the incidence and prevalence of IRU, the cause of IRU and strategies to treat it. In the meantime, people who previously had CMV retinitis should consider the risk of IRU when thinking about stopping CMV maintenance therapy.