A subscription to JoVE is required to view this content. Sign in or start your free trial.

Method Article

Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter

1.1K views

⸱

DOI:

10.3791/68422

⸱

September 16th, 2025

 ,  ,  ,  ,  ,  , 
1Shandong University of Traditional Chinese Medicine, 2Shandong Clinical Medicine Research Center, Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine

* These authors contributed equally

In This Article

Summary

The binocular wavefront optometer agrees well with traditional refraction techniques in both objective and subjective refraction measurements, offering superior accuracy and clinical utility. Its standardized protocol reduces optometrist workload and provides a more accurate refractive assessment for post-refractive surgery individuals.

Abstract

The aim is to evaluate the agreement and accuracy of refraction using a binocular wavefront optometer with the autorefractor and phoropter. To do this, 1 month after corneal refractive surgery, the right eyes of 125 subjects were enrolled in this cross-sectional study. Objective and subjective refractions were measured using a binocular wavefront optometer, an autorefractor, and a phoropter in a noncycloplegic condition. The differences and agreement of refractive data were analyzed using the Wilcoxon signed-rank test and Bland-Altman plots. The differences between sphere (Z=-0.872, p=0.38), J0 (Z=-0.065, p=0.95), J45 (Z=-1.199, p=0.23), and SE (Z=-1.316, p=0.19), objectively detected by binocular wavefront optometer and autorefractor, were not statistically significant. The differences between J0 (Z=-0.533, p=0.59), J45 (Z=-0.724, p=0.47), and SE (Z=-0.933, p=0.35), subjectively detected by binocular wavefront optometer and phoropter, were not statistically significant, whereas sphere (Z=-3.699, p<0.0001) had statistically significant differences. The Bland-Altman plots showed agreement between binocular wavefront optometer objective refraction and autorefractor in sphere (95% LoA: -1.00 D to 0.89 D), J0 (95% LoA: -0.47 D to 0.47 D), J45 (95% LoA: -0.55 D to 0.58 D), and SE (95% LoA: -0.89 D to 0.96 D). The Bland-Altman plots also showed agreement between binocular wavefront optometer subjective refraction and phoropter in sphere (95% LoA: -0.59 D to 0.82 D), J0 (95% LoA: -0.47 D to 0.43 D), J45 (95% LoA: -0.47 D to 0.43 D), and SE (95% LoA: -0.66 D to 0.74 D). Conclusively, the binocular wavefront optometer is an effective instrument, demonstrating good agreement between its objective and subjective refraction results and those obtained from autorefractor and phoropter, its smaller refractive intervals presenting a high accuracy in refractive error detection.

Introduction

Corneal refractive surgery has become one of the main modalities for correcting refractive error due to its safety, efficacy, and predictability1. Accurate measurement of refractive error is an important indicator for evaluating changes in visual quality after refractive surgery2. Currently, objective refraction measurements in clinical practice are usually detected by the autorefractor, and they are used as a starting point for subjective refraction. Subjective refraction is usually assessed by an optometrist operating the phoropter, and this optometrist-obtained subjective refraction is used as the gold standard for evaluating refractive error3,4. The resolution limit of the human eye for refractive changes in spherical lenses can reach 0.05 D4, but the autorefractor and the phoropter use 0.25 D intervals during testing. When using a binocular wavefront photometer to detect refraction, 0.05 D lens intervals have been reported to improve the proportion of eyes achieving red-green equality in the duo-chrome test compared to instruments with 0.25 D increments5.

After corneal refractive surgery, the accuracy of the autorefractor is compromised due to changes in the two refractive media, the cornea and the tear film6,7, so that the objective refraction measured by the autorefractor may differ from the subjective refractive error obtained by the optometrist. The binocular wavefront optometer, based on the principles of Hartmann-Shack and adaptive optics technology, realizes continuous measurement and improves the red-green balance ratio by decreasing the dioptric interval8. Adaptive optics are also employed to measure and correct aberrations, improving image quality and refractive error detection efficiency9,10,11. The wavefront sensor describes the optical characteristics of low and high-order aberrations in the Zernike polynomials12,13, and transforms low-order aberrations into the objective sphere and cylinder14. Based on objective results, motorized optical zoom and dual-column mirror synthetic refractive correction techniques were used to simulate 0.05 D spaced optics for subjective refraction8. It could detect spheres from -15.00 D to 15.00 D. This instrument was equipped with two electronic screens in front of the left and right eyes, respectively, to simulate various targets during the refraction process. The instrument simulated the targets appearing at different distances by presenting targets of different sizes. The optometrist detected refraction by operating electronic software connected to the instrument. Theoretically, the binocular wavefront optometer allows for a more accurate detection of refractive error. However, if the optical media were opaque, like cataracts, the instrument was unable to detect refraction.

In this study, we used the binocular wavefront optometer, the autorefractor, and the phoropter to measure the refractive error of patients 1 month after corneal refractive surgery. This study aims to assess the agreement of refractive error measurements using the binocular wavefront optometer with the autorefractor and phoropter and to determine whether the binocular wavefront optometer provides more accurate refractive prescriptions compared to the phoropter.

Access restricted. Please log in or start a trial to view this content.

Protocol

The study adhered to the tenets of the Declaration of Helsinki and was approved by the Medical Ethics Committee of the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine [Approval No. HEC-HY-2023005KY]. Informed consent was obtained from all participants. All participants who were eligible under the inclusion criteria agreed to take part. Registration Date: 2024-05-28 00:00:00; Registration number: ChiCTR2400084952; Registration database: Chinese Clinical Trial Registry.

1. Patient selection

NOTE: This cross-sectional study included 125 participants (63 males and 62 females), with the right eye selected for analysis. All participants had undergone corneal refractive surgery at the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine between August 2023 and October 2023.

  1. Inclusion criteria
    1. Include patients between the ages of 18 and 35 years diagnosed with myopia in both eyes, patients who have undergone corneal refractive surgery 1 month prior, as this time point ensures stable refractive status, and patients with correct refractive errors with spectacles for each participant before surgery, ensuring best corrected visual acuity of 20/20 or better in each eye.
  2. Exclusion criteria
    1. Exclude patients with no ocular pathological changes other than refractive error that cause postoperative vision decline, patients with refractive errors that were difficult to correct due to genetic or congenital factors, and patients with a history of color blindness, color deficiency, or significant red-green preference.

2. Treatment procedures

​NOTE: Objective and subjective refraction were performed using the autorefractor Nidek AR-310A, the phoropter, and the binocular wavefront optometer CXAZT/YGY-1 without cycloplegia, with room illumination of 100 lx. The phoropter is composed of Nidek RT-600 and Nidek SSC-350.

  1. Order of optometry
    1. Perform the first examination using the autorefractor for all participants and use simple randomization to determine the order of subsequent examinations between the binocular wavefront optometer and phoropter. Maintain a 10 min interval between examinations on different instruments following completion of subjective refraction.
  2. Binocular wavefront optometer procedures
    1. Ensure firm forehead contact with the headrest bar and secure chin positioning on the chin rest. Click the Start Test button to automatically calibrate the detection distance and measure objective refraction in 0.05 D increments.
    2. Click the Electronic Software to simulate occluding the right eye and instruct the left eye to view (not identify) the 20/20 line of optotypes. Ask participants if they cannot see optotypes; measure objective refraction again.
    3. Perform the red-green duo-chrome test. Select Green Clear to simulate adding a positive sphere lens if the green backgrounds appear clearer or select Red Clear to simulate adding a negative sphere lens if the red backgrounds appear clearer. Do not adjust the lens after participants observe equal clarity on both backgrounds15.
    4. Perform the Jackson cross-cylinder test by using electronic software to simulate two honeycomb pictures. Click to simulate adjusting the axis in 1° increments until equal clarity is observed by participants on two pictures, thereby determining the axis.
    5. Click to simulate adding a 0.10 D negative cylinder lens if the first picture is clear or add a 0.05 D positive cylinder lens if the second picture is clear. Adjust until participants observe equal clarity on both pictures, determining the cylinder. Conduct the duo-chrome test again when the cylinder and axis are modified.
    6. Repeat the above steps for the right eye examination.
    7. Ask participants to observe the two separate lines of optotypes, click Upper Sharper if the top line appears sharper, or click Lower Sharper if the bottom line is clearer. Continue until participants report equal clarity and complete the binocular balance test.
    8. Simulate adding a positive lens to fog both eyes, then increase the negative sphere lens until participants report no further improvement in visual acuity.
    9. Perform the duo-chrome test for both eyes. If red and green equality could not be achieved, choose the most negative sphere lens that red could not change to green16,17. Record a subjective refractive prescription from the binocular wavefront optometer as sphere, cylinder, and axis.
  3. Autorefractor and phoropter procedures
    1. Calculate objective refraction automatically using the autorefractor through analysis of infrared light reflected from the eye.
    2. Enter objective refraction results into the phoropter and utilize this instrument for all subsequent procedures (steps 2.3.3 to 2.3.9).
    3. Perform maximum plus to maximum visual acuity. Occlude the left eye and add a 0.25 D sphere lens to the right eye, fogging the visual acuity to 20/66. Gradually add -0.25 D sphere lens to refine the correction until the best corrected visual acuity is achieved.
    4. Conduct the red-green duo-chrome test. Add -0.25 D sphere lens if the red backgrounds appear clearer or subtract -0.25 D if the green backgrounds appear clearer. Repeat until equal clarity on both backgrounds.
    5. Present the honeycomb targets and use the Jackson cross-cylinder to compare the clarity of the two orientations. Adjust the axis in increments of 10° (or 5°) toward the negative axis (red dots) until participants see equally clear on both orientations, thereby determining the axis.
    6. Align the negative axis (P position) of the cross-cylinder with the astigmatic axis and compare the alacrity of the two targets. Add -0.25 D cylinder lens if the target is clearer when the negative axis (red dots) aligns with the axis or subtract -0.25 D cylinder lens if otherwise. Continue adjusting until clarity is consistent in both orientations, thereby determining the cylinder.
    7. Repeat steps 2.3.3 to 2.3.4 to complete the right eye refraction process. Repeat the test for the left eye following steps 2.3.3 to 2.3.6.
    8. Fog both eyes by adding +0.75 D sphere lens. Use vertical prism dissociation to separate the images for each eye. Add a +0.25 D sphere lens to the clearer image until both images appear equally clear.
    9. Remove the prism and gradually reduce the -0.25 D sphere lens until the best corrected visual acuity is achieved for both eyes. Perform the red-green duo-chrome test for both eyes. Confirm subjective refraction.
  4. Examining best corrected visual acuity
    1. Utilize trial frames containing loose trial lenses corresponding to the phoropter and binocular wavefront optometer subjective prescriptions. Set up the binocular wavefront optometer with a loose trial lens AZT-203 in 0.05 D increments. Set up the phoropter with trial case lens 266-B in 0.25 D increments.
    2. Fit both eyes with the trial lens. Randomize the order of the two trial lenses and ask the participant to wear each pair of trial lenses for 5 min.
    3. Instruct participants to wear the trial lens and measure the best corrected visual acuity of each participant's right and left eye using Snellen charts at a 6 m inspection distance. Score and record the best corrected visual acuity by line.
    4. Request participants to observe the line of targets corresponding to their optimal corrected visual acuity. Identify which trial lens provides smaller and darker clear targets. Only record trial lens results of the right eye to minimize interocular correlation bias.

3. Statistical analysis

  1. Extract the main refractive variables, including sphere, cylinder, axis, and best corrected visual acuity, from different instruments in this study. Calculate spherical equivalent (SE) using the formula:
    mean SE = sphere + [cylinder/2]
  2. Convert spherocylindrical refraction values to power vectors for astigmatism using the formulas by Thibos et al.18expressed as below with J0(axes at 180° and 90°) and J45(axes at 45° and 135°).
    J0=-(cylinder/2) x cos(2 x axis); J45=-(cylinder/2) x sin(2 x axis)
  3. Perform all statistical analyses using SPSS software package version 27.0.
  4. Assess data normality using the Kolmogorov-Smirnov test, and check whether the data follows a normal distribution. Descriptive statistics included median, lower quartiles, and upper quartiles. Compare measurement differences using the Wilcoxon signed rank test.
  5. Estimate agreement of optometric results between instruments using Bland-Altman plots. Calculate the agreement limit by taking the difference between the two measurements and multiplying the standard deviation of the mean by 1.96 and consider all tests statistically significant at 95% (p < 0.05).

Access restricted. Please log in or start a trial to view this content.

Results

To demonstrate the accuracy of the binocular wavefront optometer in refractive measurements through refraction analysis and agreement analyses, while illustrating its advantages in improving visual outcomes through best corrected visual acuity and trial lens results.

Refraction analysis
There were no significant differences in sphere (Z=-0.87, p=0.38), J0 (Z=-0.07, p=0.95), J45 (Z=-1.20, p=0.23), and SE (Z=-1.32, p=0.19) between non-cycloplegic object...

Access restricted. Please log in or start a trial to view this content.

Discussion

The binocular wavefront optometer used in this cross-sectional study is an integrated subjective-objective optometric device. The results suggested that the difference between the objective refraction measured by the binocular wavefront optometer and autorefractor was not statistically significant, and the Bland-Altman agreement plots demonstrated good agreement between the two instruments. Objective refraction measured by the binocular wavefront optometer is biased towards myopic drift compared to autorefractor results;...

Access restricted. Please log in or start a trial to view this content.

Disclosures

All authors have nothing to disclose.

Acknowledgements

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Access restricted. Please log in or start a trial to view this content.

Materials

List of materials used in this article
NameCompanyCatalog NumberComments
autorefractor Nidek LtdAR-310A A device to detect objective refraction
binocular wavefront optometerAizhitong Medical Technology Co., LtdZJAZT/BQYGY-1A device with simultaneous subjective and objective optometry and wavefront aberration analysis
phoroptorNidek Ltd Nidek RT-600 and Nidek SSC-350 A device to detect subjective refraction
trial case lens Danyang Huahui Optical Instrument Co., Ltd266-Btrial lens in 0.25 D increments used for the phoroptor
trial lensAizhitong Medical Technology Co., LtdAZT-203trial lens in 0.05 D increments used for the binocular wavefront optometer 

References

  1. Du, H., Zhang, B., Wang, Z., Xiong, L. Quality of vision after myopic refractive surgeries: Smile, fs-lasik and ICL. BMC Ophthalmol. 23 (1), 291(2023).
  2. Titiyal, J. S., et al. Small incision lenticule extraction (smile) techniques: Patient selection and perspectives. Clin Ophthalmol. 12, 1685-1699 (2018).
  3. Tabernero, J., Otero, C., Pardhan, S. A comparison between refraction from an adaptive optics visual simulator and clinical refractions. Transl Vis Sci Technol. 9 (7), 23(2020).
  4. Meyer, D., Rickert, M., Reed, O., Joret, P., Kollbaum, P. Clinical comparison of high-resolution and standard refractions and prescriptions. Optom Vis Sci. 100 (11), 751-760 (2023).
  5. Jia, T., et al. Comparison of vision performance of spectacles prescribed to 0.05d versus 0.25d steps. Clin Exp Optom. 107 (1), 66-74 (2023).
  6. Chen, Q., et al. Effects of tear film lipid layer thickness and blinking pattern on tear film instability after corneal refractive surgery. Cornea. 36 (7), 810-815 (2017).
  7. Sharma, B., et al. Impact of corneal refractive surgery on the precorneal tear film. Indian J Ophthalmol. 68 (12), 2804-2812 (2020).
  8. Lei, Y., et al. Comparisons of objective and subjective refraction with and without cycloplegia using binocular wavefront optometer with autorefraction and retinoscopy in school-age children. Graefes Arch Clin Exp Ophthalmol. 261 (5), 1465-1472 (2022).
  9. Jiang, M., Zhang, X., Puliafito, C. A., Zhang, H. F., Jiao, S. Adaptive optics photoacoustic microscopy. Opt Express. 18, 21770-21776 (2010).
  10. Szewczuk, A., Zaleska-Żmijewska, A., Dziedziak, J., Szaflik, J. P. Clinical application of adaptive optics imaging in diagnosis, management, and monitoring of ophthalmological diseases: A narrative review. Med Sci Monit. 29, e941926(2023).
  11. Hu, L., Hu, S., Gong, W., Si, K. Learning-based Shack-Hartmann wavefront sensor for high-order aberration detection. Opt Express. 27 (23), 33504-33517 (2019).
  12. Vohnsen, B., Carmichael Martins, A., Qaysi, S., Sharmin, N. Hartmann-Shack wavefront sensing without a lenslet array using a digital micromirror device. Appl Opt. 57 (22), E199-E204 (2018).
  13. Park, J. H., et al. Accuracy of an automated refractor using a Hartmann-Shack sensor after corneal refractive surgery and cataract surgery. J Cataract Refract Surg. 41 (9), 1889-1897 (2015).
  14. Chauhan, T., Sachdev, M. S. Commentary: Wavefront aberrometry-based objective refraction - accuracy versus convenience. Indian J Ophthalmol. 70 (5), 1537-1538 (2022).
  15. Martinez-Conde, S., Gantz, L., Schrader, S., Ruben, R., Zivotofsky, A. Z. Can the red-green duochrome test be used prior to correcting the refractive cylinder component. PLoS One. 10 (3), e0118874(2015).
  16. Rolandi, R., et al. Red and green defocus curves and duochrome test in different age groups. J Optom. 17 (3), 100497(2024).
  17. Wee, S. H., Yu, D. S., Moon, B. Y., Cho, H. G. Comparison of presbyopic additions determined by the fused cross-cylinder method using alternative target background colours. Ophthalmic Physiol Opt. 30 (6), 758-765 (2010).
  18. Thibos, L. N., Wheeler, W., Horner, D. Power vectors an application of fourier analysis to the description and statistical analysis of refractive error. Optom Vis Sci. 74 (6), 367-375 (1997).
  19. Cheng, M., et al. Clinical evaluation of a 0.05 d-step binocular wavefront optometer in young adults in China. Clin Exp Optom. 107 (4), 395-401 (2023).
  20. Canto-Cerdan, M., et al. Corneal epithelium thickness and refractive changes after myopic laser corneal refractive surgery. J Refract Surg. 38 (9), 602-608 (2022).
  21. Paudel, N., Adhikari, S., Thakur, A., Shrestha, B., Loughman, J. Clinical accuracy of the nidek ark-1 autorefractor. Optom Vis Sci. 96 (6), 407-413 (2019).
  22. Yi, Z., et al. Theoretical derivation and clinical validation of the resolution limit of human eye to spherical lens change: A self-controlled study. Int Ophthalmol. 43 (4), 1387-1394 (2022).
  23. Atchison, D. A., Schmid, K. L., Edwards, K. P., Muller, S. M., Robotham, J. The effect of under and over refractive correction on visual performance and spectacle lens acceptance. Ophthalmic Physiol Opt. 21 (4), 255-261 (2001).
  24. Yu, H. J., et al. Visual acuity variability: Comparing discrepancies between snellen and etdrs measurements among subjects entering prospective trials. Ophthalmol Retina. 5 (3), 224-233 (2021).
  25. Zhu, M., et al. Corneal epithelial remodeling in a 6-month follow-up period in myopic corneal refractive surgeries. J Refract Surg. 39 (3), 187-196 (2023).
  26. Alió Del Barrio, J. L., et al. Corneal stromal thickness changes after myopic laser corneal refractive surgery. J Cataract Refract Surg. 48 (3), 334-341 (2022).
  27. Ryu, I. H., Kim, B. J., Lee, J. H., Kim, S. W. Comparison of corneal epithelial remodeling after femtosecond laser-assisted lasik and small incision lenticule extraction (smile). J Refract Surg. 33 (4), 250-256 (2017).
  28. Yu, N., et al. Corneal epithelial thickness changes following smile for myopia with high astigmatism. J Refract Surg. 37 (4), 224-230 (2021).
  29. Kim, B. K., Chung, Y. T. Comparison of changes in corneal thickness and curvature after myopia correction between smile and fs-lasik. J Refract Surg. 39 (1), 15-22 (2023).
  30. Liu, P., et al. Adopting machine learning to predict nomogram for small incision lenticule extraction (smile). Int Ophthalmol. 45 (1), 175(2025).

Access restricted. Please log in or start a trial to view this content.

Reprints and Permissions

Tags

Autorefractor ComparisonPhoropter AgreementRefractive Error DetectionObjective RefractionSubjective RefractionBland-Altman PlotsPostoperative RefractionJackson Cross-CylinderRed-Green Duochrome
Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter
Contact Us
Recommend to Library

Privacy

Terms of Use

Policies

Copyright © 2026 MyJoVE Corporation. All rights reserved.