Sir,

Phacoemulsification using topical anesthesia is a safe and satisfactory procedure. Minimal pain was reported, but some patients still felt pain.1, 2, 3 To identify the sources of the pain, we encourged the patients to report pain in a ‘yes or no’ fashion once it was felt, and the exact surgical steps were recorded.

Case report

There were 162 eyes of 136 patients, including 65 males and 71 females. The mean age was 67.3 (SD±12.6) years, ranging from 18 to 91 years. Topical anesthesia was achieved by drops of lidocaine hydrochloride (2%) given for three times. Clear corneal incision of 2.65 mm was made, and it was sutured only when needed. The height of balanced salt solution bottle was set around 110 cm above the eye level. The mean operation time was 22 min (SD±7.1), ranging from 14 to 52 min. There was no association between the duration of surgery and the pain report. Pain was reported 53 times in 30 (18.5%) operations. The source of pain could be identified in 50 (94.3%) reports (Table 1). We found that younger patients and those with longer eyeball length reported pain more frequently (Table 2). Overall, 26 patients had operations of two eyes separately and the mean duration was 1.7 months (1–5 months). There was no difference in the frequency of pain report between the first or second eye operation (P=0.50, sign test).

Table 1 The steps and identified sources when patients reported pain during phacoemulsification and intraocular lens implantation (n=53)
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Table 2 The distribution of operations with or without pain-reports in different groups by sex, age, diabetes mellitus, and axial length
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Comment

Most of the pain was reported during a smooth operation, and nearly half was reported when the anterior chamber was extended by irrigation, such as too much hydration during hydrodissection, or immediately after the infusion and before the initiation of aspiration in the stages of phacoemulsification, cortex aspiration, or viscoelastic removal. It was relieved by aspiration or lowering the height of the infusion bottle. This result suggests that adequate preoperative setting of the infusion bottle height to avoid over-extension of the anterior chamber can greatly improve the patient's comfort. Particularly in eyeballs with long axial length, whose sclera resistance is less than normal, distention of the anterior chamber is more likely.