Fig. 5 The direction in which the monopolar electrode needle is advanced depends on the muscle injected. Top left. For medial rectus (MR) muscle injections the needle should be directed straight backward toward the orbital apex. For lateral rectus (LR) injections a 45-degree angle is necessary once the needle tip is past the equator. Top right. Inferior oblique (IO) injections should be directed slightly inferiorly and through the conjunctiva fornix. Bottom. Inferior rectus (IR) injections are somewhat difficult through the conjunctiva and may be easier to inject through the lower lid, especially in patients with restrictive disorders such as thyroid ophthalmopathy.