Refractive surprise after cataract surgery secondary to smeared optics of swept-source optical coherence tomography biometer: a case report

BACKGROUND: Inaccurate biometry can lead to the wrong intraocular lens implantation and result in refractive surprise following cataract surgery. It is important to be sceptical of biometry results that do not match the refractive or clinical picture and ask for it to be repeated. CASE PRESENTATION: We present a unique cause of refractive surprise in a patient undergoing cataract surgery. Pre-operative refraction demonstrated hypermetropia, yet swept-source optical coherence tomography (SS-OCT) biometry repeatedly calculated the axial length as > 35.00 mm in both eyes. The patient underwent phacoemulsification and intraocular lens insertion using the provided biometry calculations, however post-operatively the patient had a + 14.00 dioptre refractive surprise. Analysis of biometry performed on the same day identified other patients with exaggerated axial lengths, supporting the theory that the biometer’s smeared optical surface was responsible. Following servicing of the machine, repeat biometry of the patient calculated the axial length consistent with a hypermetrope (21.67 mm) and the intraocular lens exchange was successful in correcting the refractive error. CONCLUSIONS: Ensure the optical surfaces of the biometer are cleaned regularly, and consider repeating biometry on separate days if repeat biometry still is not in keeping with the refractive or clinical picture. Additionally, re-confirm the axial length with another modality.