Objective: To evaluate the usefulness of various optical and surgical treatment modalities in the treatment of patients who were symptom free in the primary position of gaze yet had symptomatic diplopia in the reading position (down gaze at near).
Patients and methods: A retrospective chart review was conducted to identify all patients with presbyopia I have treated who were symptom free in the primary position but had diplopia in down gaze associated with vertically incomitant strabismus. Of 51 patients identified, 32 were symptomatic in down gaze due to a hypertropia associated with a unilateral inferior rectus muscle underaction. Twenty-two of these patients had previously undergone recession of the affected inferior rectus muscle for treatment of thyroid eye disease; four patients, for correction of entrapment secondary to blow-out orbital fracture; and four patients, for treatment of superior oblique muscle palsy. Two patients had undergone prior surgery for superior oblique myokymia. Eight patients had horizontal diplopia associated with an A pattern, and eight patients had horizontal diplopia associated with a V pattern. Three patients had vertical and horizontal diplopia after partial recovery from third-nerve palsy.
Results: The treatment modalities were varied and individualized. Treatment consisted of optical management (20 patients), surgical management (21 patients), or a combination of both (10 patients). These treatment modalities resulted in comfortable single binocular vision for reading in 41 of the 51 patients. Successful optical treatment consisted of Fresnel prisms (four patients), slab-off prisms (two patients), single-vision readers (seven patients), switch to nonprogressive bifocal lenses (three patients), and a high bifocal segment (16 patients). Successful surgical modalities included posterior fixation of the contralateral inferior rectus muscle (10 patients), surgery for A- or V- pattern strabismus (five patients), or bilateral inferior rectus muscle recession (six patients).
Conclusion: Diplopia in the reading position frequently can be alleviated with a systematic approach that includes both optical and surgical modalities.