Intraocular lens power calculation after corneal refractive surgery.

PURPOSE OF REVIEW: Corneal refractive procedures have become increasingly popular over the past decade, allowing patients to have excellent uncorrected visual acuity and spectacle independence. As these individuals mature, many will eventually undergo cataract surgery. With the advances in modern cataract surgery and lens implant technology, particularly presbyopic intraocular lens implants, patients and physicians have greater expectations regarding visual outcomes and independence from glasses after cataract surgery. Therefore, it is important to understand methods to accurately determine intraocular lens power calculation after keratorefractive procedures to avoid refractive surprises and patient dissatisfaction. RECENT FINDINGS: In this review article, we provide an overview of intraocular lens power determination after corneal refractive surgery, highlighting sources of errors and potential methods to improve the accuracy of the lens power estimation. SUMMARY: Newer methods to address errors in intraocular lens power calculations after keratorefractive surgery represent a paradigm shift from the previous gold standard of the clinical history method. Understanding the advantages and limitations of the various methods may be beneficial in obtaining more accurate estimations of the intraocular lens power after corneal refractive surgery, resulting in improved visual outcomes.

Incidence of and risk factors for perioperative optic neuropathy after cardiac surgery.

BACKGROUND: Visual loss from optic neuropathy rarely occurs in the perioperative period in patients who have undergone nonocular surgery. We performed a retrospective, matched, case-control study to determine the incidence of perioperative optic neuropathy (PON) after cardiac surgery with the use of cardiopulmonary bypass (CPB) and to determine risk factors that may lead to this potentially devastating complication. METHODS: Medical records of all patients undergoing cardiac surgery during a 9-year period were reviewed retrospectively to identify visual loss from acute unilateral and bilateral optic neuropathy during the perioperative period that had developed in patients. Data were collected from these patients and compared with data from control subjects matched for age, gender, risk factors for vascular disease, and type of surgery to determine the incidence of and potential risk factors for PON. RESULTS: Of 9701 surgical patients requiring CPB, 11 patients (0.113%) with PON were identified. Although both the absolute and relative drop in hemoglobin during the perioperative period approached statistical significance, no other putative risk factors were identified. CONCLUSIONS: The risk of PON associated with cardiac surgery in which CPB is used is low but substantial. The factors that lead to the condition remain unknown, although the presence of systemic vascular disease and both the absolute and relative drop in hemoglobin during the perioperative period seem to be important. Because PON often causes profound permanent visual loss, we recommend that patients, particularly those with systemic vascular disease, for whom cardiac surgery with CPB is planned, be made aware of this potential complication.