HomeArticlesStatic Retinoscopy ( Skiascopy ) [ Sub – ENG ] – Retinoscopy part 1
Static Retinoscopy ( Skiascopy ) [ Sub – ENG ] – Retinoscopy part 1
November 6, 2019
Hi to everybody and welcome to OptoTubeChannel, the first Italian YouTube Channel dedicated to Optometry Today let’s talk about Static Retinoscopy, an objective technique to evaluate refractive status for far distance at the distance of 5 or 6 meters, which classically is defined the optic infinity. This technique is named “Static retinoscopy” because visual system is evaluated when its functions are static and in particular the accomodation, but this is not true because ath the distance of 5 or 6 meters or more the accomodation is not nothing or in static condition, infact there are different studies that show the presence of low LEAD between 0.20D and 0.30D which could increase whit cognitive process so there’s nothing about static in this retinoscopy… The target used during the perform of this retinoscopy is a non cognitive target to not stimulate accomodation and alterate data in a non-controlled way. So the target is a spot usually which could be in two different ways: in in projection devices enough vintage from a certain point of view we have a spot on a grey screen, while in modern device we have which show a black spot on a white ground, obviously with the 100% of the contrast The working distance for this retinoscopy is about 5 or 6 meters for the target and less than 1 meter for the practicioner position compared to the patient position. The reason of this setting is that with the retinoscope is how we simulate the light from the target, but evaluate the patient at 6 meters is not easy especially if we have to be carefull to the retinic reflex and its features so we take position nearer to the patient usually at a distance lower than 1 meter and to compensate the working distance we have to use a lens that neutralize the working distance This lens usually is of +1.50D, but it could be +1.00D or +2.00D compared to the needs of the examiner Usually this lens is +1.50D because the plus lens has a blur and control function over the accomodation and also a slight mydriatic effect and it help us in retinic reflex analysis. The lens is +1.50D quantitatively because let’s take position at 0.67 meters from patient that is the best distance to reduce eventual positioning errors. The practicioner is sat laterally and after that, retinoscope is set in the best way, so the practicioner set the retinoscope with a medium-higher lighting and directs it to the eye of the patient while he/she has to look at the target from 5 or 6 meters So with the retinoscope we have to do a particular movement known as “brush” so let’s rotate slightly from right to left and from left to right with a moving pretty slow and homogeneous So let’s observe the reflex from the point of view of movement and let’s try to neutralize it by lenses The movement could be of two types: a “with” movement that follows the rotation verse If it doesn’t follow it is an “against” movement The “with” movement is neutralized by plus lenses, the “against” movement by minus lenses The “wit” movemente represent hyperopic ametropia, while “against” movement myopic ametropia Obviously we have not to observe the movement in a only one direction, but we have to evaluate the retinic reflex also in the orthogonal direction to check eventual astigmatism If there’s a dioptrical difference between the two directions we have astigmatism so when we got the dioptrical values for both directions we can make the sphero-cylindrical lens obviously if we took the values as two spherical lenses we build from zero the sphero-cylindrical lens if we took values as spheric lens and cylindrical lens we can make our sphero-cylindrical easier What we have to do at the start, thinking about a probably astigmatism, because we doesn’t know the patient, is to rotate the streak direction in the different directions and let’s see how the movement changes, the reflex changes, in the different directions, so we could see easily about differences and we know how to set the streak direction , and what are main directions and what are the directions in which we have to evaluate retinic reflex. Then we have particular retinic reflex, for example in case of keratoconus we have a retinic reflex with the classic scissor shape, a reflex the open itself when we move fromone side to the other another particular retinic reflex is leucocoria, a white reflex caused by congenital cataracts or retinoblastoma and other ocular diseases So this is all for static retinoscopy, let’s see at the next opto-video! if you liked leave a like and subscrive channel OPTO-STYLE!!!