Hypotropic Dissociated Vertical Deviation; a Case Report
A 25-year-old woman presented with esotropia of her left eye since the age of 3 to 4 months without any prior strabismus surgery or amblyopia therapy. She was apparently in good health.\nCyclorefraction was +3.74 -0.74 × 135° in her right eye, yielding BCVA of 20/25, and +3.5 -0.5 × 60° in the left eye with BCVA of 20/40. She had mild amblyopia and latent nystagmus in her left esotropic eye with appropriate corrective glasses. Worth-4-dot and Titmus tests revealed left eye suppression and no streopsis. There was bilateral lateral rectus and inferior oblique underaction (-1) together with bilateral superior oblique overaction (+2) with mild A-pattern. The function of other extraocular muscles was normal. While fixating with her right eye, prism alternate cover test revealed 40 and 45 prism diopters (PD) of esotropia in her left eye at far (6 m) and near (33 cm), respectively in addition to hypotropia of 3 PD accompanied by slow variable downward drift from 3 to 6 PD. While fixating with the left eye, there was no change in the position of the right eye. No extorsional movement was observed during downward drift which was not associated with manifest nystagmoid or rhythmic movements. Left eye hypotropia did not change with right or left gaze or head tilt. Slit lamp and fundus examination, and applanation tonometry were within normal limits in both eyes.\nShe underwent bimedial rectus muscle recession equal to 5.25 mm with 1/3 tendon width superior transposition to correct the esotropia and A-pattern simultaneously. Three months after surgery, while fixating with her right eye, mild esotropia and hypotropia of the left eye were occasionally observed (). When fusion was completely broken by the alternate cover test, 8 PD of esotropia and 3 PD of hypotropia with 3 to 4 PD of downward drift were measureable in her left eye (). We did not perform any additional procedure for correction of her hypotropic DVD since she seemed orthophoric most of the time and was satisfied with the result of the operation.