Repeatability and Reproducibility of a New Partial Coherence Interferometer; AL-Scan Optic Biometer

The purpose of this study was to evaluate the intra-observer repeatability and inter-observer reproducibility of the ocular parameter measurements in cataract eyes using the new partial coherence interferometer, AL-Scan. Eighty-six eyes with cataracts were included in this prospective study. Axial length, average keratometry, anterior chamber depth, central corneal thickness, white-to-white distance and intraocular lens power calculation with the SRK-T formula were determined by two observers. The measurements were repeated by the same observers using the same AL-Scan unit on the same eye approximately 2 weeks later, just before surgery. Inter-observer reproducibility was excellent, with very high interclass correlation coefficients (˃0.984) for all measured parameters. Standard deviations (Sw) and coefficients of variation (CV) of the repeated measurements were low, which demonstrated high intra-observer repeatability, except for the central corneal thickness and white-to-white distance measurements (Sw≤0.224 ∞CV≤ 1.072). The precision of the measurements obtained by the AL-Scan biometer is highly reliable and observer-independent

PDF

___

1. Holladay JT. Refractive power calculation for intraocular lenses in the phakic eye. Am J Ophtalmol. 1993;116(1):63-6.

2. Fontes BM, Castro E. Intraocular lenses power calculation by measuring axial length with partial coherence and ultrasonic biometry. Arg Bras Oftalmol. 2011;74(3):166-70.

3. Olsen T. Sources of error in intraocular lens power calculation. J Cataract Refract Surg. 1992;18(2):125-9.

4. Carkeet A, Saw SM, Gazzard G, Tang W, Tan DT. Repeatability of IOLMaster biometry in children. Optom Vis Sci. 2004;81(11):829-34 . 5. Haigis W, Lega B, Miller N. Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation accordig to Haigis. Graefes Arch Clin Exp Ophtalmol. 2000;238(9):765-73.

6. Hill W, Angeles R, Otani T. Evaluation of a new IOLMaster algorithm to measure axial lenght. J Cataract Ref Surg. 2008;34(6):920-4.

7. ISO 5725. Precision of Test Methods-Determination of Repeatability and Reproducibility for a Standart Test Method by Inter-laboratory test. 2nd ed. Geneva:International Organization for Standardization;1986.

8. Freeman G, Pesudovs K. The impact of cataract severity on measurment acquisition with the IOLMaster. Acta Ophthalmol Scand. 2005;83(4):439-42.

9. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1(8476):307-10.

10. Norrby S. Sources of error in intraocular lens power calculation. J Cat Refract Surg. 2008;34(3):368-76.

11. Jin GJ, Crandall AS, Jones JJ. Intraocular lens exchange due to incorrect lens power. Ophthalmology. 2007;114(3):417-24.

12. Sahin A, Hamrah P. Clinically relevant biometry. Curr Opin Ophthalmol. 2012;23(1):47-53.

13. Packer M, Fine IH, Hoffman RS, Coffman PG, Brown LK. Immersion A-scan compared with partial coherence interferometry; outcomes analysis. J Cat Refract Surg. 2002;28(2):239-42.

14. Bhatt AB, Schefler AC, Feuer WJ, Yoo SH, Murray TG. Comparison of predictions made by the intraocular lens master and ultrasound biometry. Arch Ophthalmol. 2008;126(7):929-33.

15. Huang J, Savini G, Li J, Lu W, Wu F, Wang J, Li Y, Feng Y, Wang Q. Evaluation of a new optical biometry device for measurements of ocular components and its comparison with IOLMaster. Br J Ophthalmol. 2014;98(9):1277-81.

16. Kaswin G, Rousseau A, Mgarrech M, Barreau E, Labetuulle M. Biometry and intraocular lens power calculation results with a new optical biometry device: comparison with the gold standard. Cataract Refract Surg. 2014;40(4):593-600.

17. Bjeloš Rončevic M, Bušić M, Cima I, Kuzmanović Elabjer B, Bosnar D, Miletić D. Intraobserver and interobserver repeatability of ocular components measurement in cataract eyes using a new optical low coherence reflectometer. Graefes Arch Clin Exp Ophthalmol. 2011;249(1):83-7.

18. Olsen T. Calculation of intraocular lens power: a review. Acta Ophthalmol Scand. 2007;85(5):472-85.

19. Lam AK, Chan R, Pang PC. The repeatability and accuracy ofaxial lenght and anterior chamber depth measurements from the IOLMaster. Ophtalmic Physiol Opt. 2001;21(6):477-83.

20. Lam AK, Chan R, Woo GC, Pang PC, Chiu R. Intra-observer and inter-observer repeatability of anterior eye segment analysis system (EAS-1000) in anterior chamber confihuration. Ophtalmic Physiol Opt. 2002;22(6):552-9.

21. 21-Aramberi J, Araiz L, Garcia A, et al. Dual versus single Scheimplug camera for anterior segment analysis: precision and agreement. J Cataract Refract Surg. 2012;38(11):1934-49

22. Hoffer KL. The Hoffer Q formula: a comparison of theoretic and regressio formulas. J Cataract Refract Surg. 1993;19(6):700-12.

23. Holladay JT, Praeger TC, Chandler TY, Musgrove KH, Lewis JW, Ruiz RS. A three-part system for refining intraocular lens power calculation. J Cataract Refract Surg. 1988;14(1):17-24.

24. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg. 1990;16(3):333-40.

25. Haigis W. The Haigis formula. In: Shammas HJ, ed, Intraocular Lens Power Calculation. Thorofare, HJ: Slack, Ina. 2004;41-57.

26. Baumeister M, Terzi E, Ekici Y, Kohnen T. Comparison of manual and automated methods to determine horizontal corneal diameter. J Cataract Refract Surg. 2004;30(2):374-80.