Pharmacological approaches for the treatment of strabismus

Strabismus is an eye movement disorder characterized by misalignment of the eyes and affects 1-5% of preschool-aged children. Lack of successful treatment in children may result in amblyopia, a lasting visual impairment. Current treatments to realign the eyes include surgery and botulinum toxin (Botox). We are working to develop two potential alternative treatments. The first uses muscle-specific immunotoxins, such as ricin-MAb35 where ricin is conjugated to a monoclonal antibody to the nicotinic acetylcholine receptor. We show that this significantly weakens the treated muscle, and our studies indicate that its muscle-weakening effects last up to 24 weeks after a single injection. The second strategy uses known myogenic growth factors, such as insulin-like growth factor (IGF), to strengthen an underacting muscle. A single injection of IGF-II resulted in significant increases in muscle force generation. Our studies thus far confirm that these agents can significantly alter muscle force generation, and we are actively pursuing additional drug strategies to improve the effect and duration of these agents. If successful, these agents may provide new alternatives to surgery for the treatment of strabismus.