Tags

Type your tag names separated by a space and hit enter

Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements.
J Cataract Refract Surg 2005; 31(8):1530-6JC

Abstract

PURPOSE

To correlate intraoperative aphakic autorefraction to conventional emmetropic intraocular lens (IOL) calculations and derive an empiric predictive model for IOL estimation based on optical refractive biometry without axial length and keratometry measurements.

SETTING

Institutional Review Board of the University of Southern California, Los Angeles County General Hospital, Los Angeles, California, USA.

METHODS

A pilot group of 22 eyes of 22 patients scheduled for cataract surgery were enrolled in a prospective trial. All patients had a standard preoperative workup with subsequent cataract extraction and IOL implantation according to conventional biometric measurements and IOL calculations. Intraoperative autorefractive retinoscopy was used to obtain aphakic autorefraction and to measure the aphakic spherical equivalent before lens implantation. A linear regression analysis was used to correlate the aphakic spherical equivalent to the final adjusted emmetropic IOL power to empirically derive a refractive formula for IOL calculation (optical refractive biometry method). A second validation series of 16 eyes was used in a head-to-head comparison between the optical refractive biometry and the conventional IOL formulas. A subset of 6 eyes from the validation series were post-refractive cases having subsequent cataract surgery.

RESULTS

Intraoperative retinoscopic autorefraction was successfully obtained in all 22 patients in the pilot group and all 16 patients in the validation group. The spherical equivalent of the aphakic autorefraction correlated linearly with the final adjusted emmetropic IOL power (P<.0001, with adjusted r(2)=.9985). The relationship was sustained over an axial length range of 21.43 to 25.25 mm and an IOL power range of 12.0 to 25.5 diopters (D). In a subsequent validation series of 10 standard and 6 post-laser in situ keratomileusis (LASIK) cataract cases, the optical refractive biometry method proved to be a better predictive model for IOL estimation than conventional formulas; 83% of the LASIK eyes and 100% of the normal eyes were within +/-1.0 D of the final IOL power when aphakic autorefraction was used, compared with 67% of LASIK eyes and 100% of the normal eyes, using the conventional methodology.

CONCLUSIONS

A new model for IOL power calculation was derived based on an optical refractive methodology that breaks away from the conventional art introduced by Fyodorov in the 1960s. A purely refractive algorithm is used to predict the power of the IOL at the time of surgery without the need for axial length and keratometry measurements. This method bypasses some limitations of conventional biometry and shows promise in the post-refractive cataract cases.

Authors+Show Affiliations

Doheny Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of California at Los Angeles, Los Angeles, California 90027, USA. sean@ianchulev.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article

Language

eng

PubMed ID

16129287

Citation

Ianchulev, Tsontcho, et al. "Intraoperative Optical Refractive Biometry for Intraocular Lens Power Estimation Without Axial Length and Keratometry Measurements." Journal of Cataract and Refractive Surgery, vol. 31, no. 8, 2005, pp. 1530-6.
Ianchulev T, Salz J, Hoffer K, et al. Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. J Cataract Refract Surg. 2005;31(8):1530-6.
Ianchulev, T., Salz, J., Hoffer, K., Albini, T., Hsu, H., & Labree, L. (2005). Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. Journal of Cataract and Refractive Surgery, 31(8), pp. 1530-6.
Ianchulev T, et al. Intraoperative Optical Refractive Biometry for Intraocular Lens Power Estimation Without Axial Length and Keratometry Measurements. J Cataract Refract Surg. 2005;31(8):1530-6. PubMed PMID: 16129287.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. AU - Ianchulev,Tsontcho, AU - Salz,James, AU - Hoffer,Kenneth, AU - Albini,Thomas, AU - Hsu,Hugo, AU - Labree,Laurie, PY - 2005/01/20/accepted PY - 2005/9/1/pubmed PY - 2005/10/18/medline PY - 2005/9/1/entrez SP - 1530 EP - 6 JF - Journal of cataract and refractive surgery JO - J Cataract Refract Surg VL - 31 IS - 8 N2 - PURPOSE: To correlate intraoperative aphakic autorefraction to conventional emmetropic intraocular lens (IOL) calculations and derive an empiric predictive model for IOL estimation based on optical refractive biometry without axial length and keratometry measurements. SETTING: Institutional Review Board of the University of Southern California, Los Angeles County General Hospital, Los Angeles, California, USA. METHODS: A pilot group of 22 eyes of 22 patients scheduled for cataract surgery were enrolled in a prospective trial. All patients had a standard preoperative workup with subsequent cataract extraction and IOL implantation according to conventional biometric measurements and IOL calculations. Intraoperative autorefractive retinoscopy was used to obtain aphakic autorefraction and to measure the aphakic spherical equivalent before lens implantation. A linear regression analysis was used to correlate the aphakic spherical equivalent to the final adjusted emmetropic IOL power to empirically derive a refractive formula for IOL calculation (optical refractive biometry method). A second validation series of 16 eyes was used in a head-to-head comparison between the optical refractive biometry and the conventional IOL formulas. A subset of 6 eyes from the validation series were post-refractive cases having subsequent cataract surgery. RESULTS: Intraoperative retinoscopic autorefraction was successfully obtained in all 22 patients in the pilot group and all 16 patients in the validation group. The spherical equivalent of the aphakic autorefraction correlated linearly with the final adjusted emmetropic IOL power (P<.0001, with adjusted r(2)=.9985). The relationship was sustained over an axial length range of 21.43 to 25.25 mm and an IOL power range of 12.0 to 25.5 diopters (D). In a subsequent validation series of 10 standard and 6 post-laser in situ keratomileusis (LASIK) cataract cases, the optical refractive biometry method proved to be a better predictive model for IOL estimation than conventional formulas; 83% of the LASIK eyes and 100% of the normal eyes were within +/-1.0 D of the final IOL power when aphakic autorefraction was used, compared with 67% of LASIK eyes and 100% of the normal eyes, using the conventional methodology. CONCLUSIONS: A new model for IOL power calculation was derived based on an optical refractive methodology that breaks away from the conventional art introduced by Fyodorov in the 1960s. A purely refractive algorithm is used to predict the power of the IOL at the time of surgery without the need for axial length and keratometry measurements. This method bypasses some limitations of conventional biometry and shows promise in the post-refractive cataract cases. SN - 0886-3350 UR - https://www.unboundmedicine.com/medline/citation/16129287/Intraoperative_optical_refractive_biometry_for_intraocular_lens_power_estimation_without_axial_length_and_keratometry_measurements_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0886-3350(05)00432-3 DB - PRIME DP - Unbound Medicine ER -