Oscillopsia After Isolated Lateral Wall Decompression Versus Balanced or 3-Wall Decompression.

Purpose: To assess the incidence of postoperative masticatory oscillopsia after orbital decompression, comparing results between isolated lateral wall and balanced or 3-wall orbital decompression.

Methods: An observational retrospective study was performed, involving 161 consecutive patients who underwent orbital decompression between 2008 and 2018. Patients' clinical data were registered, and archives were revised for data compilation. Patients were divided into 2 groups according to the type of surgery: "lateral" group included patients who underwent isolated lateral wall decompression and "lateral plus" group involved patients with balanced or 3-wall decompression. Exclusion criteria were secondary decompressions, those not including lateral wall and asymmetrical surgeries, so analysis was performed among 131 remaining patients. Oscillopsia was self-reported and was registered as present or not. Diplopia was evaluated according to Paridaens grading system.

Results: Statistical analysis among the 131 patients with lateral wall decompression (isolated or in combination) was performed. Seven patients referred oscillopsia, 5 among "lateral" group, while 2 reported oscillopsia on "lateral plus" group (p = 0.001). The authors found no differences on new-onset or worsening of diplopia between groups (p = 1).

Conclusions: Oscillopsia was significantly higher after isolated lateral wall decompression than after balanced or 3-wall decompression, while no differences were found between groups according to diplopia status. Transmission of temporal muscle contraction to the orbit seems to be the cause of the oscillopsia. The authors postulate that the absence of orbital floor or medial wall may act as a dampener for the temporalis muscle contractions, allowing the orbital contents to be expanded through them, and avoiding oscillopsia.