Subjective visual sensations during cataract surgery under topical anaesthesia

Abstract

Editor, I read with interest the report by Biro & Schvoller (2008), which affirms the findings of earlier studies that most patients (89.7–100%) undergoing cataract surgery under topical anaesthesia experience at least light perception intraoperatively (Tan et al. 2005). An important finding of previous studies is that 3–19% of patients are frightened by their visual sensations (Tan et al. 2005). This is clinically significant because fear may cause a sympathetic surge, resulting in adverse side-effects such as hypertension, hyperventilation, panic attacks and ischaemic strain on the heart (Tan et al. 2005). It would be interesting to know whether any of the patients in this study reported fear and, if so, whether there was a difference in the proportion of patients experiencing fear between the group undergoing cataract surgery for the first time and those having it to the second eye. A previous study (Tranos et al. 2003) reported that 15.8% of patients undergoing surgery for the first time were frightened by their intraoperative visual sensations, compared to only 6% for those having surgery to the second eye. I agree with the authors that preoperative counselling of patients is beneficial because patients will know what to expect, and are less likely to be frightened by their visual sensations. It has been shown in a randomized controlled trial that preoperative counselling helps alleviate fear caused by intraoperative visual sensations (Voon et al. 2005). However, additional counselling on potential intraoperative visual sensations requires more time than that currently committed by surgeons, and this must be taken into consideration when planning for the amount of time spent on patients. This role may be assumed by trained nurse clinicians or paraclinical staff. It is useful to show patients drawings of possible visual sensations during the counselling because it can illustrate what patients might expect. I feel that it is important to show a variety of drawings: it has been shown that the visual experiences are quite variable between patients (Tan et al. 2005). The illustrations in Biro & Schvoller (2008)show a good range of visual sensations and would be useful during preoperative counselling.