We read the article entitled “Long-term increase in subfoveal choroidal thickness after surgery for senile cataracts” by Noda and associates. The authors evaluated the impact of cataract sugery on subfoveal choroidal thickness in the elderly. The authors concluded that most elderly patients with senile cataracts are expected to maintain increased subfoveal choroidal thickness for at least 6 months after cataract surgery. We congratulate and applaud their interesting and important work on this topic; however, we feel a couple of issues must be addressed.
Choroidal thickness has been measured to different outer choroidal boundaries, which may result in significant differences in subfoveal choroidal thickness measurements. Measuring to the inner margin of sclera could include the suprachoroidal layer, which could impact choroidal thicknesses as was reported in normal eyes. The authors should comment on whether they observed the suprachoroidal layer in their choroidal images. If present, what was the impact on the choroidal thickness measurements?
The lack of proper controls is an issue. Most of the results show a small increase in subfoveal choroidal thickness (for example, a significant increase from 193.8 μm at baseline to 209.3 μm after 6 months), which might be within the variation in measurements. Thus, having some normal age- and axial length–matched controls may be valuable for comparing choroidal thickness change after phacoemulsification in these eyes.
Noda and associates also used multiple regression model to seek factors associated with the changes of subfoveal choroidal thickness. The evaluated variables included age, gender, baseline subfoveal choroidal thickness, axial length, refractive status, and the duration of surgery. However, 2 important factors—intraocular pressure and blood pressure—were not adusted in the multivariable models. Previous studies have demonstrated that intraocular pressure, blood pressure, and the difference between them (perfusion pressure) significantly affect choroidal thickness. The changes of choroidal thickness following trabeculectomy are associated with intraocular pressure and axial length reduction as well as ocular perfusion pressure increase. In another study that evaluate choroidal changes after cataract surgery and factors affecting the changes, Ohsugi and associates also found that intraocular pressure changes is critical for evaluating the changes in choroidal thickness.
Moreover, further large-scale, high-quality studies to confirm these preliminary results would be worthwhile. We believe that our remarks will contribute to more accurate elaboration of the results presented by Noda and associates.