Direct Comparison of SVOne Obtained Refraction to Subjective Manifest Refraction

Uncorrected refractive error is the leading cause of vision impairment and the second leading cause of blindness worldwide, affecting 1 in 90 individuals (1). In the US population approximately 14 million individuals aged 12 years or older have visual impairment (defined as distance visual acuity of 20/50 or worse), of which more than 11 million individuals (2) could have their vision improved to 20/40 or better with refractive correction.

Uncorrected refractive error impacts all aspects of life, including, but not limited to, loss of employment opportunities, inability to care for family, and inability to receive an education. SVOne is smartphone-based autorefractor, powered by wavefront aberrometry, due to its portability and accuracy it presents as an effective and accessible method of detecting refractive error and dispensing spectacles for better vision (3).

In this study, for each patient, a single clinician will determine final prescription through manifest refraction, while a different clinician will determine final prescription using SVOne exam protocol. Sphere, cylinder and axis will be converted to power vectors and compared by linear regression analysis.

• Refraction (Diagnostic test): Refractive error measurement

Primary outcomes

• Sphere, cylinder and axis measurement for each patient [4 months]: the outcome includes sphere, cylinder and axis measurement (in diopter) by using both SVOne wave-guided autorefractor and subjective manifest refraction
• Comparison of two measurements on the same patient [4 months]: the outcome will include comparison of two sphere, cylinder and axis measurements (in power vectors) for each patient obtained with SVOne wave-guided autorefractor and subjective manifest refraction.

Sex: All, ages: 12 Years to 65 Years, accepts healthy volunteers

Inclusion Criteria:

* Subjects must be 12 (under 18 with parental consent) years of age and older up to 65 years of age.
* No known ocular pathology from previous clinical exams that may limit best corrected visual acuity.

Exclusion Criteria:

* Refractive error greater than +/- 14.00 diopters, or astigmatism greater than -7.00 diopters.
* Known ocular (corneal, lenticular, vitreal, or retinal) pathology that may limit BCVA.
* Best corrected visual acuity with spectacles of 20/25 or worse.
* Any previous surgical or laser procedures that may limit BCVA
* 11 years of age and younger

• Naidoo KS, Leasher J, Bourne RR, Flaxman SR, Jonas JB, Keeffe J, Limburg H, Pesudovs K, Price H, White RA, Wong TY, Taylor HR, Resnikoff S; Vision Loss Expert Group of the Global Burden of Disease Study. Global Vision Impairment and Blindness Due to Uncorrected Refractive Error, 1990-2010. Optom Vis Sci. 2016 Mar;93(3):227-34. doi: 10.1097/OPX.0000000000000796. PMID 26905537
• Vitale S, Cotch MF, Sperduto RD. Prevalence of visual impairment in the United States. JAMA. 2006 May 10;295(18):2158-63. doi: 10.1001/jama.295.18.2158. PMID 16684986
• Ciuffreda KJ, Rosenfield M. Evaluation of the SVOne: A Handheld, Smartphone-Based Autorefractor. Optom Vis Sci. 2015 Dec;92(12):1133-9. doi: 10.1097/OPX.0000000000000726. PMID 26540478