Orthoptists are trained professionals who specialize in orthoptic treatment. This is simultaneously a parametric representation of the orthoptic. This circle is called the "orthoptic" of the given hyperbola. Behavioral optometry is considered by some optometrists to have its origins in orthoptic vision therapy. The FSL was offered with full or folding stocks, plastic furniture and orthoptic sights. The prismatic lenses are used to analyze binocular vision and treat orthoptic problems. Mary Maddox pioneered the orthoptic profession and was the first documented orthoptist. The orthoptic article contains another proof, without differential calculus and trigonometric formulae.