A case of absent inferior rectus muscle: remedy procedure and considerations of pre- and post-operation

Purpose: To describe a rare phenomenon of discrepancy between imaging and intraoperative findings in a case of absent of the inferior rectus (IR) muscle, and present a new surgical technique improving eye alignment with reduced risk of anterior segment ischemia (ASI). Observations: A 63-year-old female presented with progressive fixed hypertropia of the right eye (RE) for 60 years. She had been diagnosed with pathological myopia of both eyes when she was young. Ocular examination showed a right hypertropia measuring greater than 90 prism diopters (PD) with 40PD of right esotropia with left fixation, with severely limited abduction and infraduction. Pre-operation imaging revealed elongated globes of both eyes and a thinner IR of the RE. However, the IR was found absent intraoperatively. The combination of recession of the superior rectus and modified Nishida procedure was performed in the RE, in which only the horizontal rectus inferior halves were fixed inferiorly with anchoring sutures onto the sclera without splitting the muscle bellies or transposing full horizontal rectus muscles. The success of eye alignment and cosmesis was achieved without ASI occurring for at least 6 months post strabismus surgery. Conclusions and importance: The modified Nishida procedure was a reliable method for treating a patient with an absent IR, reducing risk of ASI and proposing a new surgical strategy. This case alerts ophthalmologists to focus on the discrepancy between images and intraoperative findings, and to prepare to improvise and alter their surgical plan as necessary based on intraoperative findings.