Browsing by Author "Parikh, Shefali"

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    Likelihood ratios: Clinical application in day-to-day practice.
    (2009-05-23) Parikh, Rajul; Parikh, Shefali; Arun, Ellen; Thomas, Ravi
    In this article we provide an introduction to the use of likelihood ratios in clinical ophthalmology. Likelihood ratios permit the best use of clinical test results to establish diagnoses for the individual patient. Examples and step-by-step calculations demonstrate the estimation of pretest probability, pretest odds, and calculation of posttest odds and posttest probability using likelihood ratios. The benefits and limitations of this approach are discussed.
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    Retinal nerve fiber layer thickness in amblyopia
    (All India Ophthalmological Society, 2022-08) Parikh, Rajul; Sachdeva, Virender; Kekunnaya, Ramesh; Rao, B Venkateshwar; Parikh, Shefali; Thomas, Ravi
    Purpose: To report retinal nerve fiber layer thickness (RNFLT) in eyes with amblyopia compared with contralateral healthy eyes. Methods: In this cross-sectional study, we included patients with anisometropic amblyopia, strabismic amblyopia, and mixed amblyopia. All subjects underwent complete ophthalmic examination, including RNFLT measurement with time-domain OCT (Stratus OCT) and scanning laser polarimeter (GDX VCC). A paired “t” test was used to compare average and quadrant-wise RNFL thickness between the amblyopic and contralateral normal eyes. In addition, an analysis of variance test was used to compare various RNFL thickness parameters between the three groups. Results: A total of 33 eyes of 33 subjects with anisometropic amblyopia, 20 eyes of 20 subjects with strabismic amblyopia, and 38 eyes of 38 subjects with mixed amblyopia were included. In the anisometropic amblyopia group, the average RNFLT in the amblyopic eye was 98.2 ?m and 99.8 ?m in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 ?m (26.78) in the anisometropic eye and 150.42 ?m (23.84) in the fellow eye (P = 0.38). The difference between amblyopic and contralateral normal eye for RNFL and macular parameters was statistically insignificant in all three groups. The RNFL thickness in four quadrants was similar in the amblyopic and non-amblyopic eye between all three groups and statistically non-significant. Conclusion: Our study showed that RNFL thickness was similar in amblyopic and non-amblyopic eyes between all three amblyopia groups
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    Understanding and using sensitivity, specificity and predictive values.
    (2008-01-26) Parikh, Rajul; Mathai, Annie; Parikh, Shefali; Chandra Sekhar, G; Thomas, Ravi
    In this article, we have discussed the basic knowledge to calculate sensitivity, specificity, positive predictive value and negative predictive value. We have discussed the advantage and limitations of these measures and have provided how we should use these measures in our day-to-day clinical practice. We also have illustrated how to calculate sensitivity and specificity while combining two tests and how to use these results for our patients in day-to-day practice.