Abstract

The Inverse Knapp’s procedure, an infrequently performed transposition surgery, is typically utilized for congenital absence/hypoplasia of inferior rectus (IR) muscle or cases of double depressor palsy. Rarely, it may be indicated for addressing IR tear subsequent to orbital trauma. This report presents two cases of orbital trauma (one of which is an orbital blowout fracture) resulting in partial to near-total tear of IR. Patients presented with vertical diplopia and large angle hypertropia on the affected side (~35-40PD in primary gaze) with significant limitation in depression. FDT was negative, suggestive of a non-restrictive pathology. Intraoperatively, both patients had more than 50% tear of the muscle fibers. Both cases were managed by Inverse Knapp’s procedure with posterior scleral augmentation. Postoperatively, the patients exhibited favourable ocular alignment in primary gaze (more than 20PD decrease in vertical deviation) with an improvement in troublesome diplopia.