title: Validity and cost-effectiveness of cone adaptation test as a screening tool to detect retinitis pigmentosa.
abstract: BACKGROUND
  The cone adaptation test is to detect retinitis pigmentosa (RP) cases confirmed by electroretinogram (ERG). We present the validity and cost-effectiveness of cone adaptation test as a screening tool for detecting RP.
  
  
  METHODS
  This cross-sectional study was conducted between November 2013 and December 2013. All RP cases diagnosed by ophthalmologists of H. V. Desai Eye Hospital in the last 5 years were participated in this study. The cone adaptation test was done in photopic and scotopic illumination. Failed test means 10 s or more to complete the test under scotopic illumination. A technician who was masked for cone adaptation test finding carried out ERG. Demographics, symptoms, and history of treatment were inquired. Those with flat ERG wave in scotopic condition and corresponding clinical findings were defined as having RP. Sensitivity, specificity, and false-positive and false-negative parameters of validity were estimated. The unit cost of performing test and ERG was calculated.
  
  
  RESULTS
  All 32 RP patients (28 male, age median 23.5 ± 14.5 years) had a vision more than 6/60 and flat wave in ERG under mesopic/scotopic illumination. Thirty-one participants failed cone adaptation test. The sensitivity was 31/32 × 100 = 97%. The specificity was 100%. There was no false-positive case. Consanguinity rate among parents was 43%. The cost of testing one child using "cone adaptation test kit" was 2.5 US $. The unit cost of diagnosing RP using ERG was 10 US $.
  
  
  CONCLUSIONS
  Cone adaptation is a valid and cost-effective screening tool test for RP. The consanguinity rate among parents of an RP patient was high.
authors.affiliation: Department of Retina, H. V. Desai Eye Hospital, Pune, Maharashtra, India.
authors.forename: Rahul
authors.initials: R
authors.lastname: Deshpande
authors.affiliation: Department of Retina, H. V. Desai Eye Hospital, Pune, Maharashtra, India.
authors.forename: Prajakta
authors.initials: P
authors.lastname: Save
authors.affiliation: Department of Retina, H. V. Desai Eye Hospital, Pune, Maharashtra, India.
authors.forename: Madan
authors.initials: M
authors.lastname: Deshpande
authors.affiliation: Department of Retina, H. V. Desai Eye Hospital, Pune, Maharashtra, India.
authors.forename: Mahadev
authors.initials: M
authors.lastname: Shegunashi
authors.affiliation: Department of Retina, H. V. Desai Eye Hospital, Pune, Maharashtra, India.
authors.forename: Marium
authors.initials: M
authors.lastname: Chougule
authors.affiliation: Department of Research, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Khandekar
keywords: Electroretinogram; low vision; retinitis pigmentosa; visual functions