The symptoms of ocular MG can also be addressed by non-medicinal means. Ptosis can be corrected with placement of crutches on eyeglasses and with ptosis tape to elevate eyelid droop. Diplopia can be addressed by occlusion with eye patching, frosted lens, occluding contact lens, or by simply placing opaque tape over a portion of eyeglasses. Also, plastic prisms (Fresnel prisms) can be attached to eyeglasses of a diplopic patient, allowing for alignment of vision from both eyes in the affected direction, but are often problematic if the degree of muscle weakness, and therefore ocular misalignment, fluctuates frequently.