Vertical Tropia Following Horizontal Transposition Surgery.

Area of Science:

• Ophthalmology
• Strabismus Surgery
• Neuro-ophthalmology

Background:

• Duane syndrome and sixth nerve palsy are common conditions affecting eye movement.
• Horizontal transposition of vertical rectus muscles (HToVR) is a surgical technique used in these conditions.
• Understanding the potential side effects, such as vertical tropia, is crucial for patient management.

Purpose of the Study:

• To determine the prevalence of vertical tropia after HToVR surgery.
• To analyze the impact of HToVR on binocular function in patients with Duane syndrome or sixth nerve palsy.

Main Methods:

• Retrospective analysis of 11 patients with Duane syndrome or sixth nerve palsy who underwent HToVR.
• Data collected included pre- and post-operative deviations, binocular function, and need for further surgery.
• Botulinum toxin (BT) use and its effect on vertical deviation were also assessed.

Main Results:

• 54% of patients developed post-operative vertical tropia (mean deviation 7.6^).
• Stereoacuity improved post-operatively in most patients.
• No patients experienced diplopia or required additional surgery for the induced vertical deviation.

Conclusions:

• HToVR surgery leads to a high prevalence of vertical tropia in patients with Duane syndrome or sixth nerve palsy.
• Despite the prevalence, induced vertical deviations appear well-tolerated, without significant functional impairment or need for re-operation.