Manifest vs. Online Refraction Evaluation, clinical validation of online refraction

Uncorrected refractive errors cause significant economic implications in both
high and low income countries in terms of the loss of potential productivity
(Williams et al. (2015)). The prevalence of uncorrected refractive errors is,
despite of the available clinical services, still huge; visual impairment is in
42 percent of the cases the result of an uncorrected refractive error worldwide
(Williams et al. (2015)). Even in high income countries, this issue remains
prevalent. Therefore, the access to the available clinical services has to be
simplified. The development of an online refraction method will make a
refraction more accessible for patients and can be cost-saving. Clinicians can
easily take an online method to places where it*s needed for example in low
income countries.

There are several methods to measure a refractive error. The *golden standard*
to prescribe spectacles is a manifest refraction (Thibos, Hong, Bradley &
Applegate (2004)). This method has been described by F.C. Donders in 1864 and
is performed with trial lenses and a visual acuity chart to measure the
refraction error (Donders (1864)). Automated refraction, another refraction
method, is mainly used as a starting point for a manifest refraction and is
based on retinoscopy. (Nissman et al., (2004)).

At the moment, several online refraction methods are available. However, these
methods are not scientifically validated, unavailable in other countries
besides the United States of America (USA) or are not designed for customers.
One of these online refraction methods is Opternative (Opternative (2017)).
Opternative is currently used in the USA and is still developing (Opternative
(2017)). It*s a self-directed online refraction method by using a
computer-based response to presented stimuli with the use of a smartphone and a
computer. Another method is EyeNetra (EyeNetra (2017) & Ohlendorf, Leube & Wahl
(2016)). The use of this method is limited due to the need of special equipment
such as a portable autorefractor, an autolensometer and a phoropter. Therefore,
EyeNetra is mainly designed for optometrists and ophthalmologists. The same
applies to SVOne; this method uses a Hartmann-Shack wavefront aberrometer which
you can attach to a smartphone (Ohlendorf, Leube & Wahl (2016)). Another online
refraction method is 6over6, but this method has not been released yet (6over6,
(2017)).

There are also online visual acuity tests to measure the visual acuity only.
The mobile devices to test the visual acuity are PeekVision, 6over6,
Opternative, Eyenetra and DigiSight (Ludwig et al., (2016)).

At this day, digitalization is already affecting our way of living. Technology
can be used to design products to easily determine if someone has a refractive
error. This can, in the future, solve a big part of the problem of uncorrected
refractive errors and the leading cause of blindness worldwide. The aim of this
study is to validate a recently created online refraction method by comparing
the outcomes of the online refraction method with the *golden standard*
manifest refraction.

The aim of this study is to validate a recently created online refraction
method by comparing the outcomes of the online refraction method with the
*golden standard* manifest refraction.

Part one and part two: prospective comparative monocenter study

not applicable