417 Pak J Ophthalmol. 2021, Vol. 37 (4): 417-419 Brief Communication Reliability of Duo Chrome Test in Different Age Groups Considering Patient Satisfaction as Gold Standard Zehwa Mazhar 1 , Rabia Manzoor 2 , Shazia Kanwal 3 , Ghazala Iqbal 4 1-4 Department of Ophthalmology, King Edward Medical University, Lahore ABSTRACT Purpose: To check the reliability of the duo-chrome test in different age groups after best correction. Study Design: Descriptive, Cross Sectional Study. Place and Duration of Study: College of Ophthalmology and Allied Vision Sciences. King Edward Medical University, Lahore from September 2019 – December 2019. Methods: Forty two cooperative patients of both genders more than 15 years of age were included but patients with poor fixation, any opacity or any other ocular pathology were excluded. Equipment used was Trial box Trial frame Auto-refractor and Snellen Chart. Group 1 composed of 17 patients (15 – 35 years of age). Group 2 (36 – 60 years) had 15 patients and group 3 (age 61-80 years) comprised of 10 patients. Data was collected on self- designed Performa. Duo Chrome was dependent variable and gender was independent variable. Data was analyzed by using statistical package for social science (SPSS22.00) and chi square test was applied. Results: Out 42, 21 patients reported red, 12 reported green and 9 patients reported equally clear in the right eye. P value=0.156 showed that duo chrome test was equally reliable in every age group in the right eye. Similar results with p = 0.755 showed that duo chrome test was equally reliable in every age group in the left eye. Test when performed bilaterally, showed similar results. Out of 42 patients, 32 were satisfied and 10 were not satisfied with the test. Conclusion: Red Green duo-chrome test is equally reliable in all age groups to confirm refraction. Key Words: Duo chrome test, Refraction, Myopia, Hypermetropia. How to Cite this Article: Mazhar Z, Manzoor R, Kanwal S, Iqbal G. Reliability of Duo Chrome Test in Different Age Groups Considering Patient Satisfaction as Gold Standard. Pak J Ophthalmol. 2021, 37 (4): 417-419. Doi: 10.36351/pjo.v37i4.1118 Correspondence: Rabia Manzoor King Edward Medical University, Lahore Email: rabiajanvi@gmail.com Received: August 14, 2020 Revised: February 7, 2021 Accepted: August 06, 2021 INTRODUCTION Post refraction tests are done for the verification of subjective refraction including Duo-chrome, Plus one blur and pinhole etc. Since its introduction by Brown in 1927, the duo chrome test is a good clinical tool. 1 It is a test commonly used to refine the final sphere in refraction, which utilizes the phenomenon of transverse chromatic aberration of the eye. The patient is asked to compare the clarity of the green and red side letters on the bottom of the chart. If the green letters are clearer, sphere of +0.25 D is added and if the red letters are clear, a minus sphere of 0.25 D is added in the prescription. With best spherical correction, the letters in the red and green halves of the OPEN ACCESS mailto:rabiajanvi@gmail.com Reliability of Duo Chrome Test in Different Age Groups Considering Patient Satisfaction as Gold Standard Pak J Ophthalmol. 2021, Vol. 37 (4): 417-419 418 chart appear equally clear. Because the principle of duo chrome test is chromatic aberration and not color discrimination, it is used even with people having deficiency of color vision. The eye with excessive accommodation may still require too much negative sphere to balance red and green. Cycloplegia may be required in these cases. Duo chrome test is not used in patients with visual acuity worse than 20/30 (6/12), as the difference of 0.50 D between the two sides is too small to be distinguished. 2 The initial Duo-chrome test, which is also known as the Bichrome test, uses the principle of Chromatic aberration because the light of different wavelengths is refracted to a different extent. 3 The shortest wavelength (green) is refracted more as compared to the longest (red). The test first requires the power of the spherical lens to be known monocularly. The duo chrome test should be used after monocular refraction and shows the endpoint process of the examined eye. The prism dissociated Duo chrome test is used to match the stimulus with the accommodation of the two eyes in binocular vision. This test is initially used for presbyopia that need near add. The duo chrome test can be used clinically for the verification of final refraction for more than 60 years. The duo chrome test is used in research protocols for the final spherical adjustment of refraction and to avoid over or under distance correction. A study showed that red-green equality with fully corrected cylinder and without the cylindrical correction were not significantly different concluding that the red-green duo chrome test could be used both before and after cylindrical correction. 4 This study was carried out to see the reliability of Duo chrome test in three different age groups in a tertiary care hospital. METHODS This cross-sectional study was conducted between September 2019 to December 2019 among three groups of 42 patients. Cooperative patients of both genders more than 15 years of age were included but patients with poor fixation, any opacity or any other ocular pathology were excluded. Equipment used was Trial box Trial frame Autorefractor and Snellen Chart. Group 1 composed of 17 patients (15 – 35 years of age). Group 2 (36 – 60 years) had 15 patients and group 3 (age 61 – 80 years) comprised of 10 patients. Age, distance visual acuity, autorefraction, pinhole improvement, subjective refraction and Duo-chrome were noted. Data was collected on self-designed Performa. Duo Chrome was dependent variable and gender was independent variable. Data was analyzed by using statistical package for social science (SPSS22.00) and chi square test was applied. RESULTS This table shows that out 42, 21 patients reported red 12 reported green and 9 patients reported equally clear. P value = 0.156 shows that duo chrome test was equally reliable in every age group in the right eye. Similar results with p = 0.755 shows that duo chrome test was equally reliable in every age group in the left eye. Out of 42 patients, 32 were satisfied and 10 were not satisfied with the test. Table 1: Duo Chrome test of right eye, left eye and both eyes in different age groups. DUO_Od Total Red Green Equally Clear/Blurr Age 15 – 35 8 6 3 17 36 – 60 9 1 5 15 61 – 80 4 5 1 10 Total 21 12 9 42 DISCUSSION Uncorrected refractive disorders are the main cause of distance visual loss and around 108 Million human beings are affected by it. 5 It has been assessed that refractive errors which are not corrected (especially myopia)results in a huge financial burden i.e. around 202 Billion Dollars per year. Therefore, eradication of all the preventable reasons of visual damage including uncorrected refractive errors could lead to a fundamental financial gain. 6 In order to rectify these refractive errors standard clinical processes should be established and modernized bylatest scientific researchesso that finest prescription is offered to the patients. In another study, it was shown that the refractive end point measurements obtained from duo chrome and cross grid were well correlated and comparable, suggesting that they could be used interchangeably in most clinical settings. However, caution is needed when using measurements obtained by cross grid method in dim illumination. 7 Rabia Manzoor, et al 419 Pak J Ophthalmol. 2021, Vol. 37 (4): 417-419 Similar results were seen in a Korean study. 8 Another important point is that before performing Duo chrome test, eye should be pathologically perfect because in the presence of yellow crystalline lens, sometimes Red background appears clearer compared to Greenbackground. 9.10 Limitation of the study was that not all the refractive errors were equally represented. It was a single center study and accomodation was not disabled by cycloplegics. Ethical Approval The study was approved by the Institutional review board/Ethical review board (COAVS/892/20). Conflict of Interest Authors declared no conflict of interest. CONCLUSION Red Green duo chrome test is equally reliable in all three considered age groups as a post refraction confirmatory test as its P value is >0.05 which is non- significant and should be used by practitioners in clinical refraction. Precise Refraction is also very significant before certain surgical procedures like refractive surgery in order to avoid under or over- correction, which could later be difficult to treat. REFERENCES 1. Colligon-Bradley P. Red-green duochrome test. J Ophthalmic Nurs Technol. 1992; 11 (5): 220-222. 2. Myron Yanoff, Jay S. Duker. Ophthalmology (3 rd ed.). Mosby Elsevier, 2009: p. 67. 3. Sivak J. The validity of the bichrome (Duochrome) test. OptomVis Sci. 1975; 52 (9): 604-606. 4. Gantz L, Schrader S, Ruben R, Zivotofsky AZ. Can the red-green duochrome test be used prior to correcting the refractive cylinder component? PLoS One, 2015. 16; 10 (3): e0118874. Doi: 10.1371/journal.pone.0118874. 5. Kovin SN, Janet L, Rupert R, Seth RS, Jost JB, Jill K, et al. Serge for the Vision Loss Expert Group of the Global Burden of Disease Study a Global Vision Impairment and Blindness Due to Uncorrected Refractive Error, 1990 – 2010, Optom Vis Sci. 2016; 93 (3): 227-234. Doi: 10.1097/OPX.0000000000000796 6. Smith TS, Frick KD, Holden BA, Fricke TR, Naidoo KS. Potential lost productivity resulting from the global burden of uncorrected refractive error. Bull World Health Organ. 2009; 87 (6): 431-437. Doi: 10.2471/blt.08.055673. 7. Makgaba NT. A study to determine the use of cross cylinder in conjunction with the cross grid at distance as an alternative method for the duochrome technique amongst University of Limpopo optometry students. Available at: http://ulspace.ul.ac.za/handle/10386/2862. Accessed on 9 th June 2021. 8. Yang SM, Kim SH, Cho YA. The Usefulness of Duochrome Test for Prevention of Overcorrection in Refraction Tests of Myopic Children. J Korean Ophthalmol Soc. 2006; 47 (2): 269-272. 9. Chowdhury PH, Shah BH, Tiwar N. Brief Explanation Of Turville Infinity Balance And DuochromeTest. Intern J Med Sci Clin Res Rev. 2019; 2 (3): 60-70. 10. Keirl A, Christie C. Editors. Clinical optics and refraction: A guide for optometrists, contact lens opticians and dispensing opticians. Elsevier Health Sciences; 2007 Oct. 10. Authors’ Designation and Contribution Zehwa Mazhar; Optometrist: Concepts, Literature Search, Data Acquisition, Manuscript Preparation, Manuscript Review. Rabia Manzoor; Optometrist: Concepts, Design, Literature Search, Manuscript Preparation, Manuscript Review. Shazia Kanwal; Optometrist: Concepts, Data Acquisition, Data Analysis, Statistical Analysis, Manuscript Preparation, Manuscript Review. Ghazala Iqbal; Optometrist: Concepts, Data Acquisition, Data Analysis, Statistical Analysis, Manuscript Preparation, Manuscript Review. .…  ….