Elsevier

Ophthalmology

Volume 110, Issue 11, November 2003, Pages 2088-2092
Ophthalmology

The relationship between stereopsis and visual acuity after occlusion therapy for amblyopia

https://doi.org/10.1016/S0161-6420(03)00865-0Get rights and content

Abstract

Purpose

To investigate the relationship between visual acuity (VA) and stereoacuity after occlusion therapy in patients with various types of amblyopia.

Design

Retrospective noncomparative case series.

Participants

Sixty-one children with amblyopia caused by anisometropia with no strabismus (26 children), small angle (≤8 prism diopters) or intermittent strabismus (20), or both (15).

Methods

All were treated with occlusion therapy. Visual acuity and near stereopsis using the Titmus test (Stereo Optical Inc., Chicago, IL) were measured at each clinic visit.

Main outcome measure

The change in near stereopsis relative to distance VA after occlusion therapy.

Results

Mean age at initiation of therapy was 5.1 years (range = 3.5–8) and mean follow-up 52.3 weeks (range = 13–192). Mean duration of occlusion was 36 weeks (range = 12–102). After occlusion treatment, mean VA of all children improved from 0.43 to 0.78 (P<0.0001), whereas mean stereoacuity improved from 1167.4 seconds of arc to 101 (P<0.0001). By the last visit, 85.2% (52 of 61) of patients demonstrated at least 2 lines of improvement in VA. There was a significant linear relationship between VA and stereoacuity (P<0.001). The 26 anisometropic patients without strabismus enjoyed improvement in VA and stereopsis (P<0.0001) similar to that of the 35 with small-angle or intermittent strabismus (P<0.0001).

Conclusions

When employing occlusion therapy for amblyopia (due to anisometropia, small-angle or intermittent strabismus, or a combination), as VA improves, stereopsis generally also improves.

Section snippets

Patient data

In this retrospective study, we reviewed the charts of 61 consecutive children ages 3.5 to 8 years who met our inclusion criteria. They presented between 1994 and 2001 at the Jules Stein Eye Institute of University of California Los Angeles and were diagnosed with amblyopia. Amblyopia was defined as a difference in vision of 2 lines or greater with the VA of the amblyopic eye less than 20/30 and due to any combination of anisometropia, small-angle strabismus (≤8 prism diopters [PD]), and

Results

Of the 61 patients, 34 were male. Ages ranged from 3.5 to 8 years, with a mean of 5.1. The groups did not significantly differ in mean age. Patient-related data, including diagnoses of the 3 groups, are listed in Table 1.

The mean and standard deviation for follow-up time of all patients were 52.3 (±26.4) weeks (range = 13–192). Mean time intervals from the previous visit to the next visit for all patients were as follows: visit 1 to visit 2, 7.0 (±5.7) weeks; visit 2 to visit 3, 9.2 (±7.3)

Discussion

Stereopsis is that unique quality of binocular vision that enables us to perceive depth in visual space. During normal development, stereopsis is first measurable in those 3 to 5 months old and rapidly matures to nearly adult levels during the first 12 to 24 months of life. It arises from horizontal retinal image disparity between the foveae or other corresponding retinal points. Differing amounts of such disparity give rise to differing sensations of depth.10

Numerous studies exist concerning

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      In clinical practice, amblyopia is treated as a monocular disorder, with occlusion or penalization of the fellow eye as the most popular treatment choice (Loudon & Simonsz, 2005). Although such monocular treatments can recover visual acuity in the amblyopic eye for about 2/3 of the patients and improve stereoacuity to some degree (Group PEDI, 2005; Lee & Isenberg, 2003), several other visual functions remain deficient in clinically treated amblyopia (defined as 20/20 vision in the amblyopic eye following treatment), including contrast sensitivity at high spatial frequencies (Bradley & Freeman, 1981; Ciuffreda et al., 1991; Huang et al., 2007; Yang, Wu, Tian, & Wu, 1991) and eye–hand coordination (Suttle, Melmoth, Finlay, Sloper, & Grant, 2011). These existing results suggest that traditional treatments focusing on monocular deficits in the amblyopic eye cannot fully restore deficient monocular and binocular functions.

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    Manuscript no. 220424.

    This study was supported in part by a Research to Prevent Blindness Senior Scientific Investigator Award (SJI), New York, New York.

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