Fast Measure of Visual Acuity and Contrast Sensitivity Defocus Curves with an iPad Application

Joaquín Fernández1, 2, Manuel Rodríguez-Vallejo1, *, Ana Tauste1, César Albarrán3, Iñaki Basterra4, David Piñero5, 6
1 Department of Ophthalmology (Qvision), Vithas Virgen del Mar Hospital, Almería, Spain
2 Department of Ophthalmology, Torrecárdenas Hospital Complex, Almería, Spain
3 Optometry and Vision Sciences Department, University of Valencia, Valencia, Spain
4 Centro Oftalmológico Integral (COI), Bilbao, Spain
5 Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
6 Department of Ophthalmology (IMQO-Oftalmar), Vithas Medimar International Hospital, Alicante, Spain

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Creative Commons License
© 2019 Fernández et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain;
Tel: +34686468096; E-mail:



To evaluate the repeatability of the fast measurement of the visual acuity (VADC) and contrast sensitivity (CSDC) defocus curves with a new test as well as the agreement of measurements at far distance obtained with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart and the ClinicCSF test for measuring Contrast Sensitivity Function (CSF).


Records from fifty-nine subjects implanted with Multifocal Intraocular Lenses (MIOLs) were retrieved from our database. VADC and CSDC were measured from +1.00 D to -4.00 D in 0.50 D steps. The agreement with the ETDRS and the CSF at far distance was assessed in comparison to the 0 D location of the VADC and the CSDC, respectively. The repeatability was evaluated in 34 subjects who consecutively repeated two measures.


Median Visual Acuity (VA) was -0.1 logMAR with the VADC at 0 D of defocus and 0 logMAR with the ETDRS (p>0.05). A total of 45.8% of eyes showed no differences between both tests and the difference was less than one line of VA in 96.6% of the eyes. The intrasubject repeatability was under one line of VA along all the defocus curve except for positive defocus levels. The CSDC showed the best agreement with the CSF for 18 cycles per degree. The CSDC was less repeatable than VADC. Mean time spent on completing the VADC and CSDC was 7.81 and 7.98 minutes, respectively.


The VADC showed good agreement with the ETDRS and good repeatability despite the short testing time. In contrast, poorer repeatability was found for CSDC. Our method would facilitate the inclusion of VADC in clinical practice as it is a fast test, being also the first one including the measure of CSDC.

Keywords: Defocus curve, Visual acuity, Contrast sensitivity, iPad, Multifocal intraocular lenses, Visual performance.