Salem Lutheran School Weather Forecast 7 day Outlook Light rain Monday, temperatures as high as 44Â°F / 7Â°C, low temperature around 39Â°F / 4Â°C, probability of precipitation 89%, wind out of the ESE 8 mph / 13 km/h.
Actually, the rule of thumb is to align your eyes (straight ahead) to about 3/4 up the height of viewable area of the screen. That is, about 1/4 of the screen is above eye-level, the rest is below and this should apply to any reasonable screen size.
And f is the focal distance in meters. So if you want your computer screen 80 cm from your face that is 0.8 m. 1/D = 0.8. 1/0.8 = D. D = 1.25 = +1.25. Now just add this +1.25 to the spherical portion of your prescription (for both eyes) and voilÃ  you have computer glasses.