Intraocular lens power calculation for the equine eye.
Authors: Meister Ulrike, Görig Christiane, Murphy Christopher J, Haan Hubertus, Ohnesorge Bernhard, Boevé Michael H
Journal: BMC veterinary research
Summary
# Editorial Summary: Intraocular Lens Power Calculation for the Equine Eye As equine cataract surgery becomes more commonplace in clinical practice, achieving optimal refractive outcomes following phacoemulsification and IOL implantation requires precise preoperative biometric measurements and accurate power calculations—a challenge that has lacked breed-specific data in horses. Meister and colleagues measured keratometry, axial length via ultrasound biography, and refractive state through retinoscopy across 98 eyes from 49 horses, then applied established Binkhorst and Retzlaff IOL power formulas to determine whether these calculations were appropriate for equine use. The research examined how individual variables—breed, height at withers, sex, and age—influenced biometric values and whether meaningful differences existed between left and right eyes. By establishing normative biometric data and testing formula reliability in a substantial equine population, the authors provide practitioners with evidence-based guidance for selecting appropriate IOL powers to minimise postoperative refractive surprises. For farriers and equine professionals engaged in referral discussions or postoperative rehabilitation, understanding that IOL selection is now supported by rigorous calculations rather than extrapolation from human or other species' formulas represents a significant refinement in surgical outcomes and long-term visual function for horses undergoing cataract surgery.
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Practical Takeaways
- •When planning cataract surgery and IOL implantation in horses, use breed- and size-specific biometric data and IOL calculation formulas to minimize postoperative refractive surprises.
- •Perform standardized biometry (axial length, keratometry) and retinoscopy before cataract surgery to select the appropriate IOL power for each individual horse.
- •Account for individual variation across breeds and horse sizes when calculating IOL power, as these factors influence corneal curvature and axial length measurements.
Key Findings
- •Retinoscopy, keratometry, and ultrasonographic biometry were successfully performed on 98 healthy equine eyes to establish baseline optical parameters for IOL power calculation.
- •Corneal curvature, axial eye length, and refractive state were measured across horses of varying breeds, heights, and ages to determine influences on optical properties.
- •IOL power calculations using Binkhorst and Retzlaff formulas were established for equine eyes to reduce postoperative refractive error following phacoemulsification.
- •Comparison between left and right eyes and statistical analysis of breed, height at withers, gender, and age effects on optical measurements were evaluated.