A New Formula To Improve Axial Length Measurement With Optical Biometry In Intraocular Lens Power Calculation
Published 2023 - 41st Congress of the ESCRS
Reference: PO0400 | Type: Free paper | DOI: 10.82333/hy80-wd81
Authors: Ferdinando Cione* 1 , Marco Gioia 1 , Ilenia Di Paola 1 , Sergio Pagliarulo 1 , Ciro Sannino 1 , Margherita Di Stasi 1 , Maddalena De Bernardo 1 , Nicola Rosa 1
1Eye Unit, Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana",University of Salerno,Salerno,Italy
Purpose
To improve IOL power calculation in case of cataract surgery utilizing a formula applied to the preoperative Axial Length (AL) measurement.
Setting
University Eye Clinic, Department of Medicine and Surgery, University of Salerno, Italy
Methods
Patients that underwent cataract surgery were recruited in this retrospective, comparative study. Before surgery, patients underwent a complete ophthalmic evaluation, including optical biometry using an IOLMaster Zeiss. Same exams were repeated after surgery, using two different AL detection modalities (pseudophakic and aphakic options). AL changes between pre- and post-operative examination were evaluated. Furthermore, refractive prediction error (PE) was back-calculated with Barrett Universal-II, Hoffer-Q, Holladay-1 and SRK/T formulas. To eliminate any systematic error, constant optimization was performed trough zeroing-out the mean error (ME) for each formula. MEs and median absolute errors (MedAEs) of PEs were analyzed.
Results
Two-hundred-one operated eyes of 201 patients (100 males, mean age 73.39±7.53 years) and 201 opposite eyes were evaluated. In operated eyes, mean AL difference was −0.11±0.07mm (p<0.001) with pseudophakic option and 0.00±0.07mm (p=0.922) with aphakic option. Before constant optimization, MEs obtained using postoperative ALs–pseudophakic option were close to zero for all analyzed formulas (p>0.050). On the other hand, MEs were different from zero by using preoperative ALs and the postoperative ALs–aphakic option (p<0.001).
Conclusions
AL measurement variation after cataract surgery is probably due to a systematic error in optical biometer in case of phakic eyes. A correction factor applied to preoperative AL eliminates any systematic error in IOL power calculation without modifying the lens constant.