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Challenges and approaches in modern biometry and IOL calculation.
Saudi J Ophthalmol 2012; 26(1):7-12SJ

Abstract

The introduction of new intraocular lenses (IOLs), industry marketing to the public and patient expectations has warranted increased accuracy of IOL power calculations. Toric IOLs, multifocal IOLs, aspheric IOLs, phakic lenses, accommodative lenses, cases of refractive lens exchange and eyes that have undergone previous refractive surgery all require improved clinical measurements and IOL prediction formulas. Hence, measurement techniques and IOL calculation formulas are essential factors that affect the refractive outcome. Measurement with ultrasound has been the historic standard for measurement of ocular parameters for IOL calculation. However the introduction of optical biometry using partial coherence interferometry (PCI) has steadily established itself as the new standard. Additionally, modern optical instruments such as Scheimpflug cameras and optical coherence tomographers are being used to determine corneal power that was normally the purview of manual keratometry and topography. A number of methods are available to determine the IOL power including the empirical, analytical, numerical or combined methods. Ray tracing techniques or paraxial approximation by matrix methods or classical analytical 'IOL formulas' are actively used in for the prediction of IOL power. There is no universal formula for all cases - phakic and pseudophakic cases require different approaches, as do short eyes, long eyes, astigmatic eyes or post-refractive surgery eyes. Invariably, IOLs are characterized by different methods and lens constants, which require individual optimization. This review describes the current methods for biometry and IOL calculation.

Authors+Show Affiliations

Department of Ophthalmology, University of Wuerzburg, Germany.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

23960962

Citation

Haigis, Wolfgang. "Challenges and Approaches in Modern Biometry and IOL Calculation." Saudi Journal of Ophthalmology : Official Journal of the Saudi Ophthalmological Society, vol. 26, no. 1, 2012, pp. 7-12.
Haigis W. Challenges and approaches in modern biometry and IOL calculation. Saudi J Ophthalmol. 2012;26(1):7-12.
Haigis, W. (2012). Challenges and approaches in modern biometry and IOL calculation. Saudi Journal of Ophthalmology : Official Journal of the Saudi Ophthalmological Society, 26(1), pp. 7-12. doi:10.1016/j.sjopt.2011.11.007.
Haigis W. Challenges and Approaches in Modern Biometry and IOL Calculation. Saudi J Ophthalmol. 2012;26(1):7-12. PubMed PMID: 23960962.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Challenges and approaches in modern biometry and IOL calculation. A1 - Haigis,Wolfgang, PY - 2013/8/21/entrez PY - 2012/1/1/pubmed PY - 2012/1/1/medline KW - Cataract surgery KW - Corneal power KW - IOL calculation KW - Keratometer index KW - Optical biometry KW - Post-refractive surgery IOL KW - Problem eyes SP - 7 EP - 12 JF - Saudi journal of ophthalmology : official journal of the Saudi Ophthalmological Society JO - Saudi J Ophthalmol VL - 26 IS - 1 N2 - The introduction of new intraocular lenses (IOLs), industry marketing to the public and patient expectations has warranted increased accuracy of IOL power calculations. Toric IOLs, multifocal IOLs, aspheric IOLs, phakic lenses, accommodative lenses, cases of refractive lens exchange and eyes that have undergone previous refractive surgery all require improved clinical measurements and IOL prediction formulas. Hence, measurement techniques and IOL calculation formulas are essential factors that affect the refractive outcome. Measurement with ultrasound has been the historic standard for measurement of ocular parameters for IOL calculation. However the introduction of optical biometry using partial coherence interferometry (PCI) has steadily established itself as the new standard. Additionally, modern optical instruments such as Scheimpflug cameras and optical coherence tomographers are being used to determine corneal power that was normally the purview of manual keratometry and topography. A number of methods are available to determine the IOL power including the empirical, analytical, numerical or combined methods. Ray tracing techniques or paraxial approximation by matrix methods or classical analytical 'IOL formulas' are actively used in for the prediction of IOL power. There is no universal formula for all cases - phakic and pseudophakic cases require different approaches, as do short eyes, long eyes, astigmatic eyes or post-refractive surgery eyes. Invariably, IOLs are characterized by different methods and lens constants, which require individual optimization. This review describes the current methods for biometry and IOL calculation. SN - 1319-4534 UR - https://www.unboundmedicine.com/medline/citation/23960962/Challenges_and_approaches_in_modern_biometry_and_IOL_calculation_ L2 - https://linkinghub.elsevier.com/retrieve/pii/SJOPT135 DB - PRIME DP - Unbound Medicine ER -