To find out Type of Astigmatism, We first need to know the classification. There are many but the important ones are based on focal points and Principle meridians.
Comparison of different aspects in Contact lenses and spectacles are given below.
What is contrast?
It is created by the difference in luminance from two adjacent surfaces.
According to Michelson,
Dynamic retinoscopy is also called Near Retinoscopy because it is done while the patient is focusing on a near target(In accommodated state). The main purpose of Dynamic Retinoscopy is to find out the accommodative response of the patient(lag or lead or normal). There are different methods of performing Dynamic Retinoscopy.
To understand the clinical application of Conoid of Sturm, we need to understand its basic optics.
In simple words, we can say ” Conoid of sturm is just a representation of how rays are refracted through two different powered meridians” (eg: a sphero- cylindrical lens). So, instead of one focal point, they form two focal lines.
Static Retinoscopy can be done in two ways; using a working distance (WD) lens in front of the patient’s eye or without it.
A working distance lens is used to compensate for the distance between the examiner and the patient’s eye. Usually, the working distance is taken as arm length i.e 66cm (+1.50DS)
Before constructing a Visual Acuity Chart, we need to know and decide what kind of chart we want to construct. There are different kinds of charts for visual acuity measurement.