Letter charts are not only used to measure visual acuity, they are also used as targets for subjective refraction. This is the main reason distance acuity is measured more often than near acuity. At a long distance, accommodation is relaxed, so that the refraction can be more accurate.
Popliteal artery. The popliteal artery branches off from the femoral artery. It is located in the knee and the back of the leg. Its courses near the adductor canal and the adductor hiatus, distinctive open areas inside the thigh. At its far end, it splits into the anterior and posterior tibial arteries. During its course, the popliteal artery branches into other significant blood vessels.
Place the probe transversely at the knee crease in the popliteal fossa. Locate the popliteal artery and vein. Check the compressibility of the popliteal vein throughout the popliteal fossa. Be cautious not to mistake the often prominant muscular veins (gastrocnemius veins) for the popliteal vein. Whislt not truely deep veins they are generally large and still pose a lesser risk of embolisation. As such, you should also examine these as possible causes of the patient's symptoms.