Direct ophthalmoscopy allows examination of the retina by having light from the patient's retina form an image on the observer's retina. For this to work, the light rays from the patient's retina must exit as parallel beams and the observer's pupil and light source must be aligned. Factors like pupil size, distance between eyes, and refractive state can impact the field of view. Proper illumination of the patient's retina is also needed for visualization. Direct ophthalmoscopy provides around 2x magnification of the retina but other techniques provide higher magnification.