Most pathological processes involve complex molecular pathways that can only be modified or blocked by a combination of medications. Combination therapy has become a common practice in medicine. In ophthalmology, this approach has been used effectively to treat bacterial, fungal, proliferative/neoplastic, and inflammatory eye diseases and vascular proliferation. Combination therapy also encompasses the synergistic effect of electromagnetic radiation and medications. However, combination therapy can augment inherent complications of individual interventions, therefore vigilance is required. Complications of combination therapy include potential incompatibility among compounds and tissue toxicity. Understanding these effects will assist the ophthalmologist in his decision to maximize the benefits of combination therapy while avoiding an unfavorable outcome
