Comparison of Intraocular Lens Power Calculation Methods for Cataract Surgery after Refractive Surgery: A Retrospective Surgery

PURPOSE: To investigate the predictability of and propose guidelines for intraocular lens (IOL) power calculation in post-cataract surgery patients with prior corneal refractive surgery and suggest the guideline. METHODS: Medical records of 18 eyes of 16 patients were retrospectively evaluated for IOL power calculation predictability using three combinations of METHODS: 1) clinical history method, modified Maloney method, and the Feiz-Mannis method; 2) single-K formula versus double-K formula; and 3) Three IOL formulas (SRK/T, Holladay 1, and Hoffer Q). RESULTS: The clinical history method using the single-K formula with the SRK/T and Holliday 1 formula showed the best predictability, with an absolute error of 0.60+/-0.63 D and 0.74+/-0.60 D, respectively. The Feiz-Mannis method showed a tendency of myopic prediction, whereas the modified Maloney method showed a tendency of hyperopic prediction, especially in the patients with myopia more than 7 D prior to the refractive surgery. The double-K formula, when compared to the single-K formula, prevented hyperopic prediction when used with the clinical history method or modified Maloney method. CONCLUSIONS: IOL power calculation using the clinical history method with SRK/T or Holliday 1 formula showed the best predictability in patients after corneal refractive surgery. IOL power calculation using the modified Maloney method, however, because of the hyperopic prediction tendency, should be used cautiously, especially for patients with myopia of 7 D or more prior to the refractive surgery.

A Case of Malignant Peripheral Nerve Sheath Tumor of the Orbit

PURPOSE: To present a case of malignant peripheral nerve sheath tumor (MPNST) in the orbit. CASE SUMMARY: A 66-year-old man was evaluated for swelling of the left upper eyelid without pain that developed 2 months earlier. ACT scan and MRI of the orbit showed a large superior orbital mass with adjacent bony erosion, which had a central necrotic area. Incisional biopsy of the orbital mass was performed through a sub-brow incision. Histopathologic examination revealed a hypercellular tumor composed of spindle-shaped pleomorphic cells arranged in a fascicular pattern with necrotic foci. High-power magnification showed mitotic figures and nuclear pleomorphism. Subsequently, a malignant peripheral nerve sheath tumor was diagnosed. CONCLUSIONS: The possibility of malignant peripheral nerve sheath tumor should be considered in the differential diagnosis of an orbital mass which grows rapidly and shows bone invasion. Salvage surgery should be performed promptly to increase the likelihood of long-term survival.