We read with great interest the article by Hayashi and associates on age-related changes in corneal astigmatism in pseudophakic and phakic patients. Changes in corneal astigmatism with age have been well documented in the literature. Corneal astigmatism changes from with-the-rule astigmatism to against-the-rule astigmatism with age. An interesting aspect is the effect of cataract surgery on this natural shift in astigmatism. The literature in this regard is sparse. The authors herein provide valuable information about the age-related changes in pseudophakic patients in their comparative analysis of long-term change in astigmatism in pseudophakic and phakic patients. It is interesting to note that the change in astigmatism in psuedophakic patients follows the same trend as that in phakic patients, that is, a shift from with-the-rule to against-the-rule astigmatism.
However, we would like to discuss a few points. In the current study, the authors have found the mean corneal astigmatism in the surgery group to be greater than that in the nonsurgery group, which was statistically significant at 5 years. Considering the observation of their previous study regarding the stabilization of corneal astigmatism after surgery, the reason for such a difference even at 5 years remains uncertain. Although a few other studies do have similar findings, the superior incision in those studies possibly provides the explanation for their results. Because the present study includes only horizontal incisions, extrapolating the conclusions of the previous study to the present one is spurious.
A long-term change in the astigmatism of approximately 1.5 to 2 diopters, as shown by the authors, may affect the visual function of these patients. It would be interesting to note whether the authors found any such effect on the visual acuity in either of the 2 groups with such a change in astigmatism. This would help us to extrapolate the results of the study into practice. Knowledge of the impact of the change in astigmatism of this magnitude on visual acuity will help us to plan less enthusiastic correction of with-the-rule astigmatism in middle-aged and younger patients. At the same time, a quantification of the change vis a vis the visual function would help us in deciding the residual astigmatism to be left in cases of against-the-rule astigmatism.