In their article on visual sensation during phacoemulsification using topical versus regional anesthesia, Chung and coauthors1 erroneously attributed the postulation that “radiating wave-like visual patterns patients perceive during phacoemulsification surgery result from stimulation of photoreceptors by ultrasound energy released from the phaco probe” to Khan. This suggestion was, in fact, made by Verma.2,3 Khan proposed an optical explanation for the visualization of the phaco probe by patients.4
We conducted a similar study to compare the subjective visual experience of cataract patients during phacoemulsification and intraocular lens implantation using topical versus retrobulbar anesthesia. In this prospective randomized clinical trial, 306 cataract patients were randomized to receive topical or retrobulbar anesthesia during surgery by 1 of 3 experienced surgeons. The surgeons were familiar with both anesthetic techniques and used the one the patient was randomized to. The patients were not counseled preoperatively about potential intraoperative visual sensations and were not sedated preoperatively or intraoperatively.
We found, not unexpectedly, that more patients who had topical anesthesia reported perception of light (P<.001), colors (P<.001), and a change (increase or decrease) in light brightness during the course of the surgery (P<.001) than those who had retrobulbar anesthesia. There was, however, no statistically significant difference in the proportion of patients who saw movements, flashes, instruments, or surgeon/medical staff during the operation.
We also found that 10.4% of the patients who had topical anesthesia and 9.3% who had retrobulbar anesthesia were frightened by their visual experience, but the difference was not statistically significant.
Rengaraj Venkatesh MD
Radhakrishnan Muralikrishnan MSc
Kah-Guan Au Eong MMed(Ophth), FRCS
1. Chung CF, Lai JSM, Lam DSC. Visual sensation during phacoemulsification and intraocular lens implantation using topical and regional anesthesia. J Cataract Refract Surg 2004; 30:444-448
2. Verma D. Retained visual sensation during cataract surgery [letter]. Ophthalmology 2001; 108:1004
3. Verma D. Visual sensation in cataract surgery [reply to letter by AO Khan]. Ophthalmology 2001; 108:2158
4. Khan AO. Visual sensation in cataract surgery [letter]. Ophthalmology 2001; 108:2157-2158