Fig. 13. Locating the far points of eyes between high myopia and -3.00 D using ophthalmoscopic retinoscopy. The retinoscopist begins with the sleeve all of the way up and positioned at the intercept 33 cm from the subject's eye. In practice, this step is done as a continuation of seeking high hyperopia, as described in Fig. 12. At the intercept, the retinoscope filament is in sharp focus on the cornea and eyelids. If a sharply focused filament image on the retina is not seen, the retinoscopist then recedes until it is seen or until the retinoscopist has receded to the working distance of 66 cm. If at any point the retina is in sharp focus, the far point has been located; this point is in front of the cornea and approximately 33 cm in front of the retinoscope, where the rays converge in real space. To determine the approximate amount of myopia one, can estimate the distance from the cornea or from the intercept (whichever is easier). The intercept occurs at 33 cm from the cornea. The reciprocal of the distance in meters gives the power in diopters. A. For example, if the retinal image is in sharp focus with the retinoscope at 33 cm from the eye and 5 cm further from the eye than the intercept, the reciprocal of 0.05 is -20.00 D. B. Similar example for -3.00 D. The retinoscope is located at 66 cm. |