Clinical Study
Eye (2007) 21, 702–707; doi:10.1038/sj.eye.6702305; published online 3 March 2006
Impact of differences between eyes on binocular measures of vision in patients with cataracts
M Comas1, X Castells1, E R Acosta1 and J Tuñí2
- 1Evaluation and Clinical Epidemiology Department. Institut Municipal d'Assistència Sanitària (IMAS), Barcelona, Spain
- 2Ophthalmology Department. Institut Municipal d'Assistència Sanitària (IMAS), Barcelona, Spain
Correspondence: M Comas, Servei d'Avaluació i Epidemiologia Clínica, Institut Municipal d'Assistència Sanitaria (IMAS), Passeig Marítim 25-29, 08003 Barcelona, Spain. Tel: +34 93 248 32 91; Fax: +34 93 248 32 54. E-mail: mcomas@imas.imim.es
Received 2 September 2005; Accepted 19 January 2006; Published online 3 March 2006.
Abstract
Purpose
To assess the association of stereopsis with differences between eyes (better minus worse eye value) and the binocular value of visual acuity and contrast sensitivity, and to analyse binocular summation or inhibition phenomena owing to differences between eyes.
Methods
A cohort of 137 patients with bilateral cataracts (visual acuity of 0.3 LogMAR or worse in both eyes) was followed up through first- and second-eye cataract surgery. The patients were recruited from the ophthalmology departments of two teaching hospitals. Visual acuity, contrast sensitivity (monocular and binocular), and stereopsis were measured preoperatively, after first- and second-eye surgery. Multiple linear regression and local correlation analyses were used.
Results
Stereopsis was most strongly influenced by visual acuity in the postoperative period after first-eye surgery (standardized coefficients of 0.382 for difference between eyes and 0.356 for binocular visual acuity) and by contrast sensitivity in the postoperative period after second-eye surgery (standardized coefficients of 0.353 for the difference between eyes and -0.312 for binocular contrast sensitivity). After first-eye surgery, the correlation of the differences between eyes with stereopsis was stronger (between 0.4 and 0.5) when the differences were greater than 0.4 logMAR units for visual acuity. Slight binocular summation was found for contrast sensitivity.
Conclusions
When assessing the indication for and outcomes of cataract surgery, analysis of visual function should include measures of both eyes, rather than measures of the operative eye only, as differences between eyes (better minus worse eye value) may play an important role in binocular measures such as stereopsis.
Keywords:
cataract extraction, visual acuity, contrast sensitivity, binocular vision
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