Fortunately, extraocular disease can usually be treated effectively with systemic therapy should it occur. This study is expected to clarify the advantages and disadvantages of local therapy alone versus a combination of local therapy and oral systemic prophylaxis. ISIS 2922 ISIS 2922 is an antisense strand of 21 nucleotides, a synthetic oligonucleotide. Because of this specificity, it may generate less viral resistance. Median time to progression of retinitis was 8 weeks in patients who had been unsuccessfully treated with IV ganciclovir.
Toxicities are significant, however.
The drug appears to cause an inflammation of the iris in some cases, which responds to topical steroids. A series of clinical trials is under way to further evaluate ISIS 2922. As yet, where this interesting compound fits into the framework of CMV treatment and whether it will produce a lower incidence of resistance remain to be seen. Conclusion Local therapy for CMV retinitis with long-acting agents may be the safest, most effective means of controlling CMV retinitis with minimal systemic drug toxicity. However, the advantages provided by local therapy, including reduced incidence of adverse effects and of development of tolerance to the medication, must be weighed against the loss of protection from extraocular disease if no systemic therapy is used.