Adjust the spherical power at an interval of 0.25D to find the red-green balance point
confusion
CROSS, RETINA
Standard subjective refraction was performed using a standard phoropter. The monocular best vision sphere was determined using the Duochrome chart to ensure the circle of least confusion was on the retina before conducting Jackson Cross Cylinder (JCC). The circle of least confusion was maintained on the retina as cylinder power was increased. Once cylinder power and axis were calculated, the sphere was refined to best-corrected visual acuity (BCVA) with minimum minus power. Binocular balance using alternate occlusion technique was then conducted to best binocular VA to BCVA with minimum minus power.Binocular balanced refraction results were placed in a trial frame and the eye not being tested was occluded. Subjects were asked to give a response as to whether the letters on the red or green side of the Duochrome were clearer. If the subject reported the red side being clearer, minus power was added in 0.25D steps until equality between red and green was achieved. If the subject reported the green side being clearer, then plus 0.75D was added so that red became clearer. The same step as previously described for when the side was clearer was then performed. The final sphere was where equality was first achieved between the red and green letters of the Duochrome. If equality could not be achieved, then the final sphere was the point where the next 0.25D change made green clearer. The final sphere, and previously calculated cylindrical power and axis were recorded for the final prescription.