Reversed Fixation Test as a Means to Differentiate between Dissociated and Non-Dissociated Strabismus.

Area of Science:

• Ophthalmology
• Strabismology
• Neuro-ophthalmology

Background:

• Dissociated vertical deviation (DVD) is a strabismus characterized by an upward deviation of one eye.
• Accurate measurement of DVD is crucial for diagnosis and treatment planning.
• Existing tests like the Bielschowsky Filter Test have limitations in quantifying DVD, especially when co-occurring with other deviations.

Purpose of the Study:

• To evaluate the efficacy of the Reversed Fixation Test (RFT) in quantifying dissociated vertical deviation (DVD).
• To compare the diagnostic capabilities of the RFT with the classical Bielschowsky Filter Test.
• To assess the RFT's ability to differentiate DVD from esotropia with elevation in adduction.

Main Methods:

• The study involved 30 patients with suspected or diagnosed DVD.
• The Reversed Fixation Test (RFT) was performed by darkening the fixing eye and brightening the deviating eye while switching fixation.
• The Bielschowsky Filter Test was used as a comparative method to measure DVD.

Main Results:

• The RFT revealed a significantly larger DVD component (16.3 ± 4.9±) compared to the Bielschowsky Filter Test (3.4 ± 3.2±).
• In seven patients, the Bielschowsky Filter Test yielded a zero value for DVD, whereas the RFT showed significant DVD values ranging from 8 to 20±.
• The RFT demonstrated effectiveness in quantitatively differentiating DVD from esotropia with elevation in adduction.

Conclusions:

• The Reversed Fixation Test (RFT) is a more sensitive and quantitative method for measuring dissociated vertical deviation (DVD) compared to the Bielschowsky Filter Test.
• RFT provides valuable clinical data for differentiating DVD from other vertical strabismus conditions, improving diagnostic accuracy.
• This enhanced measurement capability of RFT can lead to more precise treatment strategies for patients with complex strabismus.