Comment on “Preoperative asymmetry is a risk factor for reoperation in involutional blepharoptosis”

Dear Sir, we read with great interest the article entitled "Preoperative asymmetry is a risk factor for reoperation in involutional blepharoptosis" by Suga H. et al.1 Basing on a large series of cases, the authors clearly examined the risk factors for reoperation in involutional blepharoptosis, showing its significant association with preoperative asymmetry. We fully agree with the authors that several factors may affect correction and that asymmetry must be carefully evaluated preoperatively. Since both levator muscles are innervated from a single midline nucleus producing equal neural output to both sides, the less affected eyelid may be capable of maintaining a normal level of elevation due to excessive nerve stimulation determined by the more ptotic eyelid, as stated by the Herring's law.

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