The authors evaluated the relationship between visual acuity and visual field or OCT parameters in a large number of glaucoma patients and healthy controls. They showed that visual acuity of glaucomatous eyes correlated with both visual field and OCT parameters, but that correlation was stronger with visual field parameters than with OCT parameters.
Visual acuity is associated with cognitive function, the mechanism of which is similar to that of the visual field in terms of the visual pathway from the eye to the visual cortex. Further, even though it is known that the central visual field is well preserved in advanced glaucoma, there is still a possibility that central sensitivity around the fixation point will be decreased and that visual acuity will be statistically affected. OCT parameters have a floor effect in that thickness values reach a lower limit from which they do not decrease further with glaucoma progression. This phenomenon might explain visual acuity's lesser correlation with OCT parameters than with visual field parameters in Suzuki et al.'s study.
Another explanation of the current study's result could be the different transmission of light during OCT imaging in pseudophakic eyes. As the study included pseudophakic eyes as well as eyes with mild cataract, the OCT parameters might have shown lower signal strength and less correlation with visual acuity relative to the visual field parameters.
In conclusion, the current study is a well-designed one highlighting the importance of visual acuity and the associated visual field and OCT parameters. We always need to preserve visual function, including visual acuity, in glaucoma patients.