This document discusses retinoscopy and how to calculate prescriptions from retinoscopy findings. It provides examples of how to subtract working distances and cycloplegic drug values from retinoscopy measurements. It also gives rules for determining signs of cylinders and examples of converting retinoscopy measurements into spectacle prescriptions with spherical and cylindrical powers.

1. RATINOSCOPY
calculation
BY SUJIT KUMAR
saraswati-eye-care.business.site

2. RATINOSCOPE
CONVERGING
5 CMS 10 CMS 50 CMS 100 CMS
66 cms
• 1 D MYOPIA 100 CMS
• 1.5 D MYOPIA 66 CMS
• 2 D MYOPIA 50 CMS
• 20 D MYOPIA 5 CMS

3. EXAMPLE DISTASNCE ATROPINE
+6.00DS +5.00DS +4.00DS
DISTANCE SUBTRACTION
• 1 mt =1 D
• 2/3 mt =1.50 D
CYCLOPLEGIC
• ATROPINE = -1.00 D
• HAMATROPINE = -0.50 D
• CYCLOPENTOLATE = -0.75 D

4. Few Algebraic rules for signs of Cylinders
• (-) (-) = (+)
• (-) (+) = (+)
• -6.00 -4.00 = -10.00
• -6.00 +4.00 = -10.00

5. Some Important steps
• While doing retinoscopy,we need to substract the working distance or
cyloplegic Drug value from the Horizontal and Verticle meridian.
• Then we assume the smallest power as the spherical value.
• Then the assume value as spherical value need to the substracted from the
other value use

6. “
”
-2.00 (180 axis)
-3.00
(90 axis)
-2.00-(+1.00) = -2.00-1.00 = -3.00 -3.00 180 axis
-3.00-(+1.00) = -3.00-1.00 = -4.00 -4.00
= -3.00 90 axis
= -4.00-(-3.00)=- 4.00+3.00 = -1.00
Spectale number = -3.00 D sph. / -1.00 D cyl *90

7. “
”
+2.00 (180 axis)
+4.00
(90 axis)
+2.00-(+1.00) = +2.00-1.00 = +1.00 +1.00 180 axis
+4.00-(+1.00) = +4.00-1.00 = +3.00 +3.00
= +1.00 90 axis
= +3.00-(-1.00)=-+3.00-1.00 = +2.00
Spectale number = +1.00 D sph. / +2.00 D cyl *90

8. “
”
-2.00 (180 axis)
+5.00
(90 axis)
-2.00-(+1.00) = -2.00-1.00 = -3.00 -3.00 180 axis
+5.00-(+1.00) = +5.00-1.00 = +4.00 +4.00
= -3.00 90 axis
= -4.00-(-3.00)=- 4.00+3.00 = +7.00
Spectale number = -3.00 D sph. / +7.00 D cyl *90

9. “
”
+2.00 (180 axis)
-3.00
(90 axis)
+2.00-(+1.00) = +2.00-1.00 = +1.00 -3.00 180 axis
-3.00-(+1.00) = -3.00-1.00 = -4.00 -4.00
= +1.00 90 axis
= -4.00-(+1.00)=-4.00-1.00 = -5.00
Spectale number = +1.00 D sph. / -5.00 D cyl *90

10. “
”
-2.00*90(Verticle)/-1.00*180(Horizontal)/66cm(WD)
-2.00*90(Verticle)/-3.00*180(Horizontal)/50cm(WD)
+3.00*90(Verticle)/+1.00*180(Horizontal)/66cm(WD)
-5.00*90(Verticle)/-4.00*180(Horizontal)/50cm(WD)
+4.00*90(Verticle)/-3.00*180(Horizontal)/50cm(WD)
-4.00*90(Verticle)/+5.00*180(Horizontal)/66cm(WD)
QUESTION
 POWER - (WORKING DISTANCE )= FINAL VALUE
 Mean POWER – (SPHERICAL POWER) = FINAL CYLINDER POWER