ACCURATE CALIBRATION FOR EYEGLASSES
To be able to prescribe eyeglasses, we need to have the patient´s subjective response when setting the lenses in a trial frame. We call this kind of examination "subjective calibration". Sometimes, and especially in children and young adults, this subjective response may vary depending on the time of day. This variation is due to the accommodation or focusing power which the ciliary muscle of the eye presents.
In the cases in which we find a variation in subjective calibration, an objective prescription should be made and it will not depend on the patient's response. This type of calibration is performed under the effect of eye drops that paralyze the eye focus (cyclopentolate). This way, we can know the real prescription to contrast with the patient´s subjective calibration.
In the events when we cannot obtain the patient´s response, as in the case of young children and disabled patients, this would be the only way to make a reliable and accurate prescription.