April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Comparison of a Novel Cell Phone-Based Refraction Technique (NETRA) With Objective Clinical Retinoscopy
Author Affiliations & Notes
  • Veerendranath Pesala
    Hyderabad Eye Research Foundation,
    L V Prasad Eye Institute, Hyderabad, India
  • Sangeetha Srinivasan
    Bausch and Lomb School of Optometry,
    L V Prasad Eye Institute, Hyderabad, India
  • Ethan Solomon
    MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
  • Vitor F. Pamplona
    MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
    Instituto de Infomática, UFRGS, Porto Alegre, RS, Brazil
  • Manuel M. Oliveira
    MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
    Instituto de Infomática, UFRGS, Porto Alegre, RS, Brazil
  • Ramesh Raskar
    MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
  • Shrikant Bharadwaj
    Hyderabad Eye Research Foundation,
    Bausch and Lomb School of Optometry,
    L V Prasad Eye Institute, Hyderabad, India
  • Footnotes
    Commercial Relationships  Veerendranath Pesala, None; Sangeetha Srinivasan, None; Ethan Solomon, None; Vitor F. Pamplona, None; Manuel M. Oliveira, None; Ramesh Raskar, None; Shrikant Bharadwaj, None
  • Footnotes
    Support  DBT Ramalingaswami Fellowship (SRB), Alfred P. Sloan Research Fellowship (RR), CNPq-Brazil fellowships 305613/2007-3, 142563 /2008-0, 200763/2009-1, 200284/2009-6, 476954/2008-8 (VFP and MMO)
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 2852. doi:
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      Veerendranath Pesala, Sangeetha Srinivasan, Ethan Solomon, Vitor F. Pamplona, Manuel M. Oliveira, Ramesh Raskar, Shrikant Bharadwaj; Comparison of a Novel Cell Phone-Based Refraction Technique (NETRA) With Objective Clinical Retinoscopy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2852.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : Uncorrected refractive errors are the largest cause of avoidable blindness in developing countries. The effectiveness of population-based vision screening programs significantly enhanced if a rapid, cost-effective and quantitative method for estimating the refractive-errors is available. A novel cell-phone based technique (NETRA) has been designed to rapidly quantify the refractive-error status of the eye. This study determined the accuracy and precision of this prototype device in determining spherical refractive error in adults, in comparison to gold-standard objective retinoscopy.

Methods: : The optical setup of NETRA consists primarily of a pinhole mask and is retrofit on a high-resolution cell phone (Samsung Behold IITM) that displays a spatially resolved pattern of red-green lines to the subject. Refractive error is estimated by subjectively aligning the red-green patterns using a custom-designed user-interface on the cell phone. In this study, cycloplegic spherical refractive errors (SR) of the dominant eye of 29 adults (mean ± SD age: 23.1 ± 2.6yrs), with best-corrected visual acuity of 20/20, were measured thrice using the NETRA and averaged. SE of the same eye was also determined using objective restinoscopy performed by an experienced Optometrist.

Results: : Cycloplegic SR of the subjects ranged from -6.25D to +3.00D. The SR determined by NETRA was well correlated with that of objective retinoscopy (r=0.96) and the two measures were not statistically significantly different from each other (p=0.14). Orthogonal linear regression fit to the plot of SR determined by NETRA against those determined by retinoscopy had a slope of 0.86 and a y-intercept of -0.22D. The mean (± 1SD) deviation for the three measures of SR determined by NETRA across all subjects was 0.18 ± 0.15D.

Conclusions: : When compared to objective retinoscopy, NETRA slightly underestimated the myopic and hyperopic cycloplegic refractive errors and had a small myopic offset of 0.22D. NETRA estimated myopic and hyperopic refractive errors with a mean precision of 0.18D. These suggest that NETRA could be used as an effective tool for rapidly estimating refractive errors in a vision-screening program. Accuracy of this novel prototype device in estimating refractive errors is expected to increase as technology evolves.

Keywords: refraction • clinical (human) or epidemiologic studies: systems/equipment/techniques • clinical research methodology 
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