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Agreement between subjective and predicted high and low contrast visual acuities with a double-pass system

Authors:
Joaquín Fernández at Qvision
Joaquín Fernández
  • Qvision
Francisco Javier Martinez Peña
Francisco Javier Martinez Peña
David P Pinero at University of Alicante
David P Pinero
Noemí Burguera at Qvision
Noemí Burguera
  • Qvision
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Abstract and Figures

Purpose: To evaluate the agreement between subjective high and low contrast visual acuity (VA) and predicted values from double-pass system measurements in healthy candidates to laser refractive surgery. Methods: Ninety-two eyes measured during the preoperative screening to laser refractive surgery were included in this retrospective analysis. High contrast subjective visual acuity (HCVA) and low contrasts at 20% (LCVA20) and 9% (LCVA9) were compared with the predicted VA obtained with a commercial double-pass system (OQAS) at the same levels of contrast, 100% (OV100), 20% (OV20), and 9% (OV9). The agreement was evaluated with Bland-Altman analysis computing the limits of agreement (LoAs) and the correlations with the spearman rho. Results: An underestimation of VA was obtained with the double-pass system for the highest contrast. Differences between predictive and subjective measurements were statistically significant for 100% contrast (− 0.08 logMAR, p < 0.0005), but not for 20%(− 0.03 logMAR, p = 0.07) and 9%(− 0.02 logMAR, p = 0.9) of contrasts. The LoAs increased with the decrease of contrast from 0.29 with 100% to 0.39 logMAR with 9% of contrast. A weak correlation was obtained between subjective and predicted VA (rho ≤ 0.33) that was only significant for 100% (p = 0.001) and 20% (p = 0.004) contrasts. Conclusion: Mean differences between methods were reasonably small so mean results obtained for predicted VA in OQAS studies can be considered as reliable, at least in healthy subjects and for low contrast. However, limits of agreement were considerably poor which means that OQAS cannot replace individual subjective measurements of VA in clinical practice.
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REFRACTIVE SURGERY
Agreement between subjective and predicted high and low contrast
visual acuities with a double-pass system
Joaquín Fernández
1
&Manuel Rodríguez-Vallejo
1
&Javier Martínez
1
&Noemi Burguera
1
&David P Piñero
2,3
Received: 7 July 2020 / R evised: 23 September 2020 / Accepte d: 20 October 2020
#Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract
Purpose To evaluate the agreement between subjective high and low contrast visual acuity (VA) and predicted values from
double-pass system measurements in healthy candidates to laser refractive surgery.
Methods Ninety-two eyes measured during the preoperative screening to laser refractive surgery were included in this retro-
spective analysis. High contrast subjective visual acuity (HCVA) and low contrasts at 20% (LCVA20) and 9% (LCVA9) were
compared with the predicted VA obtained with a commercial double-pass system (OQAS) at the same levels of contrast, 100%
(OV100), 20% (OV20), and 9% (OV9). The agreement was evaluated with Bland-Altman analysis computing the limits of
agreement (LoAs) and the correlations with the spearman rho.
Results An underestimation of VA was obtained with the double-pass system for the highest contrast. Differences between
predictive and subjective measurements were statistically significant for 100% contrast (−0.08 logMAR, p< 0.0005), but not for
20% (−0.03 logMAR, p=0.07)and9%(−0.02 logMAR, p= 0.9) of contrasts. The LoAs increased with the decrease of contrast
from 0.29 with 100% to 0.39 logMAR with 9% of contrast. A weak correlation was obtained between subjective and predicted
VA (rho ≤0.33) that was only significant for 100% (p=0.001)and20%(p=0.004) contrasts.
Conclusion Mean differences between methods were reasonably small so mean results obtained for predicted VA in OQAS
studies can be considered as reliable, at least in healthy subjects and for low contrast. However, limits of agreement were
considerably poor which means that OQAS cannot replace individual subjective measurements of VA in clinical practice.
Keywords Visual acuity .Low contrast .Optical quality .Double-pass .Prediction .Agreement
Key messages
What was known:
Double-pass technique provides objective clinical data of the optical quality of the eye
New Information:
Mean visual acuity predicted using double-pass technique is in a good agreement with mean subjective visual acuity
in healthy subjects. The system can be used to predict mean visual acuity on a sample of healthy subjects.
The mean difference decreases with the reduction in contrast, better agreement in visual acuity for 9% of contrast
than for 100% of contrast
The bias between methods is such as extended that hardly the predicted visual acuity can properly predict the
subjective visual acuity for individual measurements in clinical practice
*Manuel Rodríguez-Vallejo
manuelrodriguezid@qvision.es
1
Department of Ophthalmology (Qvision), Vithas Virgen del Mar
Hospital, 04120 Almería, Spain
2
Department of Optics, Pharmacology and Anatomy, University of
Alicante, Alicante, Spain
3
Department of Ophthalmology (IMQO-Oftalmar), Vithas Medimar
International Hospital, Alicante, Spain
https://doi.org/10.1007/s00417-020-04987-z
/ Published online: 31 October 2020
Graefe's Archive for Clinical and Experimental Ophthalmology (2021) 259:1651–1657
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... The HD Analyzer was used for assessing clinical optical quality with both intraocular lenses (IOLs). 1 One of our studies was cited to argue that this instrument was useful for characterizing the optical quality of the IOLs. 2 Moreover, we would like to clarify that our study was conducted with phakic healthy subjects, and we pointed out that the device had limitations on the measurement of multifocal IOLs, particularly due to infrared wavelength (780 nm) and the first pass nonlimited exclusively by the diffraction of the aperture. 2 Although the limitation on estimating visual performance with diffractive IOLs through objective clinical measurements is well known for a long time, not only for double-pass systems 3 but also for aberrometers, 4 there is still an overuse of these systems in clinical studies for multifocal IOL comparison. ...
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... The ICB00 exceeded the ZXR00 in all 3 measures obtained from the OQAS, which is a useful instrument for characterizing the optical quality of IOLs. 44 The ZXR00 offered consistent and excellent visual performance, with minimal degrees of visual disturbance in comparison with other multifocal IOLs. 8,25,33,37,[45][46][47] However, it showed poor optical quality compared to the ICB00, which showed results similar to those for monofocal IOLs. ...
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Article
  • Jul 2019
Purpose: To assess the influence of angle kappa (κ) and angle alpha (α) on visual quality after multifocal intraocular lens (IOL) implantation. Setting: Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China. Design: Prospective case series. Methods: Patients with cataract had phacoemulsification with TECNIS Symfony IOL implantation. The preoperative angle κ and angle α were measured using the iTrace device. Distance, intermediate, and near visual acuities were recorded 3 months postoperatively. The Optical Quality Analyzing System was used to measure the objective scatter index (OSI), modulation transfer function (MTF) cutoff frequency, and Strehl ratio. A patient questionnaire was also administered. Results: The study comprised 29 patients (57 eyes). Monocularly, the mean postoperative logarithm of the minimum angle of resolution (logMAR) uncorrected distance, intermediate, and near visual acuities were 0.03 ± 0.09 (SD), 0.05 ± 0.11, and 0.11 ± 0.09, respectively. The mean postoperative logMAR corrected distance, distance-corrected intermediate, and distance-corrected near visual acuities were -0.01 ± 0.05, 0.04 ± 0.09, and 0.11 ± 0.08, respectively. The mean OSI, MTF cutoff, and Strehl ratio were 1.27 ± 0.84, 32.03 ± 10.80 cycles per degree, and 0.17 ± 0.05, respectively. The OSI (r = 0.398, P = .005), MTF (r = -0.437, P = .002), and Strehl ratio (r = -0.419, P = .003) values were significantly correlated with angle κ. There was no correlation with angle α. Conclusions: Angle κ affected the objective visual quality multifocal after IOL implantation. The decision to implant a multifocal IOL should be carefully considered for patients with a large angle κ.
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