Does Partial Occlusion Promote Normal Binocular Function?

Abstract

PURPOSE. There is growing evidence that abnormal binocular interactions play a key role in the amblyopia syndrome and represent a viable target for treatment interventions. In this context the use of partial occlusion using optical devices such as Bangerter filters as an alternative to complete occlusion is of particular interest. The aims of this study were to understand why Bangerter filters do not result in improved binocular outcomes compared to complete occlusion, and to compare the effects of Bangerter filters, optical blur and neutral density (ND) filters on normal binocular function.METHODS. The effects of four strengths of Bangerter filters (0.8, 0.6, 0.4, 0.2) on letter and vernier acuity, contrast sensitivity, stereoacuity, and interocular suppression were measured in 21 observers with normal vision. In a subset of 14 observers, the partial occlusion effects of Bangerter filters, ND filters and plus lenses on stereopsis and interocular suppression were compared. RESULTS.Bangerter filters did not have graded effect on vision and induced significant disruption to binocular function. This disruption was greater than that of monocular defocus but weaker than that of ND filters. The effect of the Bangerter filters on stereopsis was more pronounced than their effect on monocular acuity, and the induced monocular acuity deficits did not predict the induced deficits in stereopsis.CONCLUSIONS. Bangerter filters appear to be particularly disruptive to binocular function. Other interventions, such as optical defocus and those employing computer generated dichoptic stimulus presentation, may be more appropriate than partial occlusion for targeting binocular function during amblyopia treatment. (Invest Ophthalmol Vis Sci. 2012; 53:6818-6827)

Binocular vision in amblyopia: structure, suppression and plasticity

“…Results are shown for different subjects, the denser the filter in front of one eye, the more the balance shifts in favour of the unfiltered eye. Lens blur and Bangerter filters have similar effects . Similarly, in amblyopia where there is an initial imbalance of the inputs of the two eyes due to suppression, lens blur, neutral density filters or Bangerter filters could potentially be used in front of the sighted eye to reduce suppression and re‐balance the inputs of the two eyes .…”

“…stereopsis). Both neutral density filters and Bangerter filters are less than ideal choices when it comes to stereoscopic function . The way in which they affect the signal emanating from the sighted eye turns out to be particularly detrimental for stereopsis.…”

Spatial and Global Sensory Suppression Mapping Encompassing the Central 10° Field in Anisometropic Amblyopia

“…measured using a tumbling E version of the Bailey-Lovie logMAR chart at a standard luminance of 200 cd/m 2 . 49 Best refractive correction was determined by subjective refraction and, if necessary, a trial frame correction was used during testing for both groups. Binocular vision was assessed using the Worth-4-Dot test, 50 the stereo acuity test (Randot Preschool Test; Stereo Optical Co., Inc., Chicago, IL, USA) and the cover/ uncover test was used to ensure the absence of strabismus.…”

Development Assessment of Natural Latex Membranes: A New Proposal for the Treatment of Amblyopia

“…One of the methods used for the treatment of amblyopia is optical correction followed by occlusion of the eye with better visual acuity to enable the weaker eye to develop 2 . Research on the effects of occlusion has shown that secondary deprivation effects may arise from fixation of the eye and that the occlusion time should not be longer than 6 hours 3 . This trend has also been observed in the ophthalmic community in Brazil, although there is a lack of national clinical evidence 4 .…”