New algorithm for toric intraocular lens power calculation considering the posterior corneal astigmatism
| Autor: | Douglas D. Koch, Carmen Canovas, Patricia A Piers, Joseph J.K. Ma, Sanjeev Kasthurirangan, Aixa Alarcon, Robert Rosén |
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| Rok vydání: | 2017 |
| Předmět: |
Adult
Male Optics and Photonics Visual acuity Biometry genetic structures medicine.medical_treatment Physics::Medical Physics Visual Acuity Physics::Optics Intraocular lens Astigmatism law.invention Cornea 03 medical and health sciences 0302 clinical medicine Lens Implantation Intraocular law medicine Humans Mathematics Retrospective Studies Lenses Intraocular Phacoemulsification Keratometer medicine.diagnostic_test Corneal Topography Middle Aged medicine.disease Corneal topography eye diseases Sensory Systems Vergence (optics) Ophthalmology 030221 ophthalmology & optometry Surgery Intraocular lens power calculation Female sense organs medicine.symptom Algorithm 030217 neurology & neurosurgery Algorithms |
| Zdroj: | Journal of cataract and refractive surgery. 44(2) |
| ISSN: | 1873-4502 |
| Popis: | To assess the accuracy of toric intraocular lens (IOL) power calculations of a new algorithm that incorporates the effect of posterior corneal astigmatism (PCA).Abbott Medical Optics, Inc., Groningen, the Netherlands.Retrospective case report.In eyes implanted with toric IOLs, the exact vergence formula of the Tecnis toric calculator was used to predict refractive astigmatism from preoperative biometry, surgeon-estimated surgically induced astigmatism (SIA), and implanted IOL power, with and without including the new PCA algorithm. For each calculation method, the error in predicted refractive astigmatism was calculated as the vector difference between the prediction and the actual refraction. Calculations were also made using postoperative keratometry (K) values to eliminate the potential effect of incorrect SIA estimates.The study comprised 274 eyes. The PCA algorithm significantly reduced the centroid error in predicted refractive astigmatism (P .001). With the PCA algorithm, the centroid error reduced from 0.50 @ 1 to 0.19 @ 3 when using preoperative K values and from 0.30 @ 0 to 0.02 @ 84 when using postoperative K values. Patients who had anterior corneal against-the-rule, with-the-rule, and oblique astigmatism had improvement with the PCA algorithm. In addition, the PCA algorithm reduced the median absolute error in all groups (P .001).The use of the new PCA algorithm decreased the error in the prediction of residual refractive astigmatism in eyes implanted with toric IOLs. Therefore, the new PCA algorithm, in combination with an exact vergence IOL power calculation formula, led to an increased predictability of toric IOL power. |
| Databáze: | OpenAIRE |
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