Value of dual biometry in the detection and investigation of error in the preoperative prediction of refractive status following cataract surgery
Version of Record online: 21 FEB 2010
© 2010 The Authors. Journal compilation © 2010 Royal Australian and New Zealand College of Ophthalmologists
Clinical & Experimental Ophthalmology
Volume 38, Issue 3, pages 255–265, April 2010
How to Cite
Charalampidou, S., Dooley, I., Molloy, L. and Beatty, S. (2010), Value of dual biometry in the detection and investigation of error in the preoperative prediction of refractive status following cataract surgery. Clinical & Experimental Ophthalmology, 38: 255–265. doi: 10.1111/j.1442-9071.2010.02211.x
- Issue online: 21 APR 2010
- Version of Record online: 21 FEB 2010
- Received 2 August 2009; accepted 3 November 2009.
- cataract surgery;
- refractive result;
- Zeiss IOL Master
Purpose: To report the value of dual biometry in the detection of biometry errors.
Methods: Study 1: retrospective study of 224 consecutive cataract operations. The intraocular lens power calculation was based on immersion biometry. Study 2: immersion biometry was compared with optical coherence biometry (OCB) in terms of axial length, anterior chamber depth, keratometry readings and the recommended lens power to achieve emmetropia. Study 3: prospective study of 61 consecutive cataract operations. Both immersion and OCB were performed, but lens power calculation was based on the latter.
Results: Study 1: 115 (86%), 101 (75.4%), 90 (67.2%) and 50 (37.3%) of postoperative spherical equivalents were within ±1.5 dioptres (D), ±1.25 D, ±1 D and ±0.5 D of the target, respectively. Study 2: excellent agreement between axial length readings, anterior chamber depth readings and keratometry readings by immersion biometry and OCB was observed (reflected in a mean bias of −0.065 mm, −0.048 mm and +0.1803 D, respectively, in association with OCB). Agreement between the lens power recommended by each technique to achieve emmetropia was poor (mean bias of +1.16 D in association with OCB), but improved following appropriate modification of lens constants in the Accutome A-scan software (mean bias with OCB = −0.4 D). Study 3: 37 (92.5%) and 23 (57.5%) of operated eyes achieved a postoperative refraction within ±1 D and ±0.5 D of target, respectively.
Conclusion: Systematic errors in biometry can exist, in the presence of acceptable postoperative refractive results. Dual biometry allows each biometric parameter to be scrutinized in isolation, and identify sources of error that may otherwise go undetected.