Nowadays, many strabismologists wonder how the existence of A & V patterns could have escaped the attention of ophthalmologists until so recently in the second half of the twentieth century.

Esotropia with V pattern increases in downward gaze and decreases in upward gaze.

Exotropia with V pattern increases in upward gaze and decreases in downward gaze.

Esotropia with A  pattern increases in upward gaze and decreases in downward gaze.

Exotropia with A pattern increases in downward gaze and decreases in upward gaze.

Asthenopia is a common complaint in patients with A and V patterns which may cause visual discomfort during reading or near work. On the other hand, an increase in the deviation in upward gaze is usually tolerated by most patients.

The primary and downward positions are the most important functional gazes of the eyes. For me, I do not operate for the single purpose of decreasing the deviation in upward gaze.

The safest procedure in correcting A & V patterns is the vertical displacement of the insertions of the horizontal muscles, the rule is to displace the MR muscle toward the closed angle of the A&V and displace the LR muscle toward the open angle of the A&V. This procedure is effective not only in conjunction with symmetrical horizontal surgery but also with recession-resection operations on one eye. A 5- to 8-mm displacement of the muscle usually is sufficient; lesser amounts are rarely effective.