14 comments

  1. shouldn’t retinoscopy reflex be from the internal limiting membrane (instead of external limiting membrane)?

    1. The internal limiting membrane is transparent. Otherwise, the photoreceptors beneath would not receive light.

  2. Can u explain about working distance is minus or we jst subtract from plus lens.. We can do retinoscopy by placing +1.50 plus lens in trail frame??? Minus plus confuse?

    1. Working distance can be accounted for in two methods: one, the easiest and most common is to simply subtract -1.5 diopters from the lenses in your hand or the phoropter. The other method is to add a +1.5 lens to the trial frame or phoropter setting (there is a dial setting for this that automatically accounts for it. The dioptric power of the working distance that must be subtracted is the inverse of your working distance in meters (how far away from your retinoscope the lenses are being held). Holding the lenses 50cm away from your retinoscope is (1/0.50m) = 2 D. To know your personal working distance, one should measure it sometime with a tape measure.

  3. Que- in which case appearance of the retinoscopy reflex changed, and which color of appearance we will get?

    1. Color changes are most notable when the refractive error is large. If the streak is dim, it indicates that stronger lenses must be tried. Brighter streaks occur as gets closer to neutrality.

    1. Modern retinoscopes are generally used in the plano mirror position (sleeve all the way down for Welch Allyn type retinoscopes and sleeve all the way up for Copeland type retionscopes). Reversing the sleeve all the way to the concave positon is typically just used for confirmation of the streak and guidance toward minus lenses, such as if one is not seeing with-motion in the plano mirror setting.

    1. If one has with movement the light is still being focused behind (posterior to) the retina and one needs to add plus power to have the focal point shift forward to the retinal plane (neutralized). If one sees against movement, it is because the light is being focused in front of the retina and the image “reverses” when it reflects back. Adding divergent power (minus lenses) pushes this focal point back until there is again neutrality and no movement with or against.

  4. After determining the spherical component during retinoscopy, before you scope for cylinder component in the other meridian. Is Sph lens removed or kept in the trial frame?

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