Corneal Curvature Measurements Utilizing a New Swept-source Optical Coherence Tomography Tomey OA-2000® and Comparison With IOL Master® 500 in Pterygium Patients

Mohd Radzi Hilmi, Khairidzan Mohd Kamal, Mohd Zulfaezal Che Azemin, Mohd Hafidz Ithnin, Md Muziman Syah Md Mustafa, Firdaus Yusof@Alias, Norsham Ahmad


Introduction: Corneal curvature (CC) is an important anterior segment parameter. This study compared CC measurements conducted with two optical devices in pterygium eyes.

Methods: Sixty pterygium eyes of 30 patients were enrolled in this study. CC was measured three times with the optical biometer and topography-keratometer Tomey OA-2000 (Tomey Corporation, Nagoya, Japan), then with partial optical coherence interferometry (PCI) IOL Master 500 (Carl Zeiss Meditec, Dublin, CA) and data were statistically analysed.

Results: The measurements revealed in a mean CC of 43.86 ± 1.57 D with Tomey OA-2000 and 43.84 ± 1.55 D with IOL Master. Distribution of data is normal, and no significance difference in CC values was detected (P = 0.952) between the two devices. Correlation between CC measurements was highly significant (r = 0. 99; P < 0.0001). The mean difference of CC values between devices was 0.017 D and 95% limit of agreement was -0.088 to 0.12. Duration taken for measurements with the standard biometer IOL Master was longer (55.17 ± 2.24 seconds) than with Tomey OA-2000 (39.88 ± 2.38 seconds) in automatic mode. Duration of manual measurement with Tomey OA-2000 in manual mode was shorter (28.57 ± 2.71 seconds).

Conclusion: In pterygium eyes, CC measured with Tomey OA-2000 and IOL Master showed similar values, and high correlation was observed between these two devices. This shows that both devices can be used interchangeably. Tomey OA-2000 is better in terms of faster to operate and has its own topography systems.


Pterygium; Corneal Curvature; IOL Master 500; Tomey OA-2000; Corneal Topography

Full Text:



Altan-Yaycioglu, R. et al., 2013. Astigmatic changes following pterygium removal: comparison of 5 different methods, Indian J Ophthalmol, 61(3), pp.104–108.

Bandyopadhyay, R. et al., 2010. Ocular surface disorder in pterygium; Role of conjunctival immersion cytology, Indian J Pathol Microbiol, 53(4), pp.692–695.

Barkana, Y. et al., 2005. Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low-coherence reflectometry pachymeter, and ultrasound pachymetry, J Cataract Refract Surg, 31(9), pp. 1729–1735.

Bueno-Gimeno, I. et al., 2013 Anterior chamber depth measurement in teenagers. Comparison of two techniques, J Optom, 6(3), pp.161–166.

Chen, Y.A., Hirnschall, N. & Findl, O. 2011. Evaluation of 2 new optical biometry devices and comparison with the current gold standard biometer, J Cataract Refract Surg, 37(3), pp.513-517.

Dehnavi, Z. et al., 2015. Comparison of the Corneal Power Measurements with the TMS4-Topographer, Pentacam HR, IOLMaster, and Javal Keratometer, Middle East Afr J Ophthalmol, 22(2), pp.233–237.

Elbaz, U. et al., 2007. Comparison of different techniques of anterior chamber depth and keratometric measurements, Am J Ophthalmol, 143(1), pp.48–53.

Hashemi, H. & Mehravaran, S. 2007. Corneal changes after laser refractive surgery for myopia: Comparison of Orbscan II and Pentacam findings, J Cataract Refract Surg, 33(5), pp.841–847.

Hashemi, H. & Mehravaran, S. 2010. Day to day clinically relevant corneal elevation, thickness, and curvature parameters using the orbscan II scanning slit topographer and the pentacam scheimpflug imaging device, Middle East Afr J Ophthalmol, 17(1), pp.44–55.

Holzer, M.P., Mamusa, M. & Auffarth, G.U. 2009. Accuracy of a new partial coherence interferometry analyser for biometric measurements, Br J Ophthalmol, 93(6), pp.807–810.

Huang, J. et al., 2017. Repeatability and interobserver reproducibility of a new optical biometer based on swept-source optical coherence tomography and comparison with IOLMaster, Br J Ophthalmol, 101(4), pp.493-498.

Huynh, S.C. et al. 2006 An evaluation of keratometry in 6-year old children, Cornea, 25, pp.383–387.

Khairat, Y.M. et al., 2013. Evaluation of corneal changes after myopic LASIK using the Pentacam®, Clin Ophthalmol, 7, pp.1771–1776.

Kheirkhah, A. et al. 2012. Effects of pterygium surgery on front and back corneal surfaces and anterior segment parameters, Can J Ophthalmol, 47(5), pp.423–428.

Kheirkhah, A. et al., 2012. Effects of pterygium surgery on front and back corneal astigmatism, Int Ophthalmol, 32, pp.251–257.

Kim, E.J. et al., 2015. Repeatability of posterior and total corneal curvature measurements with dual Scheimpflug-Placido tomographer, J Refract Surg, 41(12), pp.2731-2738.

McAlinden, C. & Moore, J.E. 2010. Comparison of higher order aberrations after LASIK and LASEK for myopia, J Refract Surg, 26(1), pp.45–51.

McAlinden, C. 2012. Corneal refractive surgery: past to present, Clin Exp Optom, 95(4), pp.386–398.

Tennen, D.G., Keates, R.H. & Montoya, C. 1995. Comparison of three keratometry instruments, J Cataract Refract Surg, 21, pp.407–408.

Mehravaran, S. et al., 2014. Keratometry with five different techniques: a study of device repeatability and inter-device agreement, Int Ophthalmol, 34(4), pp.869–875.

Nakakura, S. et al., 2012. Comparison of anterior chamber depth measurements by 3-dimensional optical coherence tomography, partial coherence interferometry biometry, Scheimpflug rotating camera imaging, and ultrasound biomicroscopy, J Cataract Refract Surg, 38(7), pp.1207–1213.

Norrby, S. 2008. Sources of error in intraocular lens power calculation, J Cataract Refract Surg, 34(3), pp.368–376.

Ozsutcu, M. et al., 2014. Tear osmolarity and tear film parameters in patients with unilateral pterygium, Cornea, 33(11), pp.1174–1178.

Rosa, N. et al., 2006. Anterior chamber depth measurement before and after photorefractive keratectomy: comparison between IOL master and Orbscan II, Ophthalmology, 113(6), pp.962–969.

Rosa, N. et al., 2011. Reliability of the IOLMaster in Measuring Corneal Power Changes After Hyperopic Photorefractive Keratectomy, J Cataract Refract Surg, 27(4), pp.293–298.

Salouti, R. et al., 2010. Comparison of anterior chamber depth measurements using Galilei, HR Pentacam, and Orbscan II, Optometry, 81(1), pp.35–39.

Savini, G. et al., 2016. Estimating the Preoperative Corneal Power With Scheimpflug Imaging in Eyes That Have Undergone Myopic LASIK, J Refract Surg, 32(5), pp.332-336.

Sheppard, A.L. & Davies, L.N. 2010. Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500, Ophthal Physiol Opt, 30(2), pp.143–151.

Shirayama, M. et al., 2009. Comparison of corneal powers obtained from 4 different devices, Am J Ophthal, 148(4), pp.528–535.

Twa, M.D., Coral-Ghanem, C. & Barth, B. (2003) ‘Corneal topography and contact lenses’ in Mannis, M.J., et al., (eds.) Contact lenses in ophthalmic practice. New York: Springer-Verlag; 2003.

Vives, P.P. et al., 2013. Topographic corneal changes in astigmatism due to pterygium’s limbal-conjunctival autograft surgery, J Emmetropia, 4, pp.13–18.

Wang, Q. et al., 2017. Central corneal thickness and its relationship to ocular parameters in young adult myopic eyes, Clin Exp Optom, 100(3), pp.250-254.

Wang, W. et al., 2017. Precision of a new ocular biometer in eyes with cataract using swept source optical coherence tomography combined with Placido-disk corneal topography, Sci Rep, 7(1), pp.13736. doi: 10.1038/s41598-017-13800-7.

Whang, W-J., Byun, Y-S. & Joo, C-K. 2012. Comparison of refractive outcomes using five devices for the assessments of preoperative corneal power, Clin Exp Ophthalmol, 40, pp.425–432


Article Metrics

Metrics Loading ...

Metrics powered by PLOS ALM


Indexed by:


Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at

stats View My Stats.