Cataract surgery is commonly performed under topical or regional anaesthesia (intraconal, extraconal and sub-Tenon's blocks). As the effect of local ophthalmic anaesthesia on the optic nerve is transient and often incomplete, it is logical to expect that patients may retain sufficient visual function to be able to see during the surgery . This has been shown to be the case in several studies, and most patients (80–100%) undergoing cataract surgery under topical or regional anaesthesia retain at least light perception in the operated eye during the surgery [1–12]. Many patients also report experiencing a variety of other intraoperative visual sensations, such as movements, flashes, colours and changes in light brightness; and they may also see surgical instruments, the surgeon's hands or fingers and the surgeon [1–12]. Since between 3% and 16.2% of patients have found these visual experiences frightening, this visual phenomenon is clinically significant [1–8,11].
Anaesthesiologists and other anaesthesia providers play a vital role in the perioperative management of patients undergoing cataract surgery. During their preoperative interview, patients may ask whether they can expect to see anything during the surgery. In addition, any fear experienced as a result of intraoperative visual sensations may cause a sympathetic surge which can result in hypertension, tachycardia and/or panic attacks [13,14]. These undesirable stress responses may require intervention, such as sedation or the administration of sympatholytics. For these reasons, it is crucial that anaesthesia providers are aware of the range of visual sensations that patients may encounter during the surgery, the potential effects of these sensations on the patient and the importance of appropriate counselling that such sensations are to be expected to allay patient's anxiety.
Our study aimed to assess the knowledge, beliefs and attitudes of anaesthesia providers on the possible intraoperative visual experiences of patients undergoing cataract surgery under topical anaesthesia and regional anaesthesia. We also sought their opinions on whether patients might be frightened by these visual sensations and whether preoperative counselling helps to alleviate such fear. To the best of our knowledge, a similar survey has never been reported previously.
Anaesthesia providers from three different countries – the United States of America (USA), United Kingdom (UK) and Singapore – who are routinely involved in the perioperative management of ophthalmic patients were included in this survey. The institutional review board or the Ethics Committee relevant to the country concerned approved this study. In the USA and UK, postal surveys were sent to all members of the Ophthalmic Anaesthesia Society (OAS) and the British Ophthalmic Anaesthesia Society (BOAS), respectively, and respondents were asked to complete and return the structured questionnaire by mail. No follow-up questionnaires or reminders were sent to non-responders. In Singapore, there is no professional society equivalent to the OAS or BOAS. We therefore randomly selected practicing anaesthesiologists in all the major public-sector general hospitals (Alexandra Hospital, National University Hospital, Tan Tock Seng Hospital, Singapore General Hospital and Changi General Hospital) and, because of the small geographic size of Singapore, we brought the survey forms directly to the participants. However, the investigator did not interview the participants actively, but was able to clarify any doubts while they were completing the form.
The members of the OAS included anaesthesiologists, nurse anaesthetists and ophthalmologists, while membership of the BOAS comprised anaesthesiologists and ophthalmologists. In Singapore, all participants were anaesthesiologists.
The participants were asked whether they believed that patients undergoing cataract surgery under topical and regional anaesthesia might experience light perception and a variety of other visual sensations (movement, flashes, colours, surgical instruments, the surgeon's hands and fingers, the surgeon, and a change in light brightness). They were also asked whether they thought that patients might be frightened by their visual experiences during the surgery, whether they believed that this fear may be alleviated by preoperative counselling, and whether they routinely counselled their patients on potential intraoperative visual sensations pre-operatively.
Statistical analyses were carried out using SPSS version 11.5 (SPSS Inc, Chicago, IL, USA). The χ2 tests were used to compare the results of various groups, with P-values <0.05 considered statistically significant.
Of a total of 179 participants who completed the questionnaire, 50 (27.9%) were from the USA, 69 (38.5%) from the UK and 60 (33.5%) from Singapore. The overall response rate was 35.7% (179 of 502), with the individual country response rates as follows – USA 15.5% (50 of 322), UK 57.5% (69 of 120) and Singapore 100% (60 of 60). A total of 146 anaesthesiologists (81.6%), 10 ophthalmologists (5.6%) and 23 nurse anaesthetists (12.8%) responded to the survey. There were 117 male (65.4%) and 62 female (34.6%) respondents.
The proportions of respondents who felt that patients might experience the different visual sensations are detailed in Table 1, shown individually by country and as a group. Their opinions on the possibility of patients experiencing fear intraoperatively and the need for preoperative counselling are listed in Table 2.
The respondents were grouped into those with and without any previous experience in the perioperative management of patients during cataract surgery under topical and regional anaesthesia, respectively, and the differences in their responses to the various questions were analysed (Table 3).
The responses of those who routinely counsel their patients on the possibility of visual experiences during cataract surgery under topical and regional anaesthesia were compared to those who do not (Table 4).
The majority of respondents believed that patients may experience light perception and other visual sensations during cataract surgery under local anaesthesia. Many also felt that fear resulting from these visual sensations is clinically significant and may be alleviated by preoperative counselling. This is of importance since an anaesthesia provider is more likely to take the time before the surgery to counsel patients in detail if he believes that intraoperative visual experience is of clinical significance to the surgical outcome and that preoperative counselling is potentially beneficial to the patient.
Under regional anaesthesia, 86.0% believed that patients would retain light perception at least part of the time during the surgery and the overall proportion of respondents who believed that patients might experience other unformed visual sensations ranged from 76.0–82.1%. For surgery under topical anaesthesia, 82.7% thought that patients would have light perception, and 76.5–81.6% thought that patients would encounter additional unformed visual sensations. These beliefs are borne out by recent clinical studies which show that the majority of patients (80% to 100%) retain at least some light perception during cataract surgery under local anaesthesia (topical or regional anaesthesia) and a large proportion of them also experience other unformed visual sensations [1–12].
A relatively lower proportion of respondents believed that it is possible for patients to lose light perception throughout the surgery – 53.6% for regional anaesthesia and 33.0% topical anaesthesia. While the actual percentage of patients who experience loss of light perception is low (0–20%) [1–12],it is nevertheless significant because the loss of light perception during the surgery can be alarming to some patients and may lead them to erroneously believe that an intraoperative complication has occurred. It is therefore important for anaesthesia providers to be aware of this important fact.
For the more complex (formed) visual images (surgical instruments, hands/fingers or the surgeon), a lower proportion of respondents believed that patients might experience these, ranging from 36.3–44.7% under regional anaesthesia and 53.1–59.2% for topical anaesthesia. Since previous studies have shown that some patients experience these visual sensations intraoperatively [1–12], it is important for anaesthesia providers to be aware that they can occur.
Only 51.7–78.0% of respondents believed that patients might find their intra-operative visual experiences frightening for regional anaesthesia, and 44.9–80.0% believed this for topical anaesthesia. In both categories, the respondents from Singapore were more likely to think so than those from the other two countries. The response of the Singapore anaesthesiologists to this question is similar to that found in a survey of Singapore optometry students . It may be possible that reports on this visual phenomenon from several studies that have been conducted in Singapore may have heightened their awareness [2–4]. An encouraging fact is that a high percentage of respondents believed that pre-operative counselling on the possibility of intra-operative visual sensations would help alleviate fear: 88.3–96.0% for regional anaesthesia and 62.3–98.0% for topical anaesthesia. However, not all respondents translate this belief into practice. Only 10.0–65.2% routinely counsel their patients for cataract surgery under regional anaesthesia and 10.0–53.3% did so for topical anaesthesia. In both these categories, the numbers from Singapore were low compared to the other two countries. This may be due to a difference in anaesthetic practice in Singapore, where there are no specially trained ophthalmic anaesthesiologists, and ophthalmologists rather than anaesthesiologists administer regional ophthalmic blocks before proceeding with the surgery while the anaesthesiologists monitor the patients perioperatively. Regardless of the reason, this is an issue that needs to be addressed since a multicentre randomised clinical trial showed that patients who were given additional detailed counselling about potential intraoperative visual sensations were less likely to find their visual experience frightening compared to those who were not counselled .
An important finding in our study is that of those who routinely counsel their patients, a much higher proportion believe that preoperative counselling helps to alleviate fear compared to those who do not counsel their patients (P = 0.021 for regional anaesthesia and P < 0.001 for topical anaesthesia). However, the proportion who believed that visual sensations might be frightening was not statistically different between those who routinely counsel their patients and those who do not (Table 4).
Anaesthesia providers who routinely counsel their patients were more likely to have previously been told by their patients either that the patients could see during the surgery (P < 0.001 for both regional and topical anaesthesia) or that they were frightened (P = 0.013 for regional anaesthesia and P < 0.001 for topical anaesthesia). Nonetheless, the proportion of those with this foreknowledge that patients might be frightened who subsequently counsel patients was still low (32.5% for regional anaesthesia and 46.8% for topical anaesthesia) (Table 4).
Besides what patients previously reported to them, practical experience with a specific type of local anaesthesia seems to be an important factor in determining the knowledge of anaesthesia providers. Those who have previously monitored patients undergoing cataract surgery under topical anaesthesia were more likely to believe that patients may experience the various visual sensations, that these may be frightening, and that preoperative counselling helps compared with those who have not. The differences in proportions were statistically significant for all questions except for loss of light perception and the ability to see the surgeon (Table 3). This difference was not apparent in the case of those who have monitored patients under regional anaesthesia, possibly because the number of anaesthesia providers who have not monitored patients under regional anaesthesia was small (10 respondents).
Our study shows that the majority of anaesthesia providers in the USA, UK and Singapore are aware that patients may experience a variety of visual sensations during cataract surgery under regional or topical anaesthesia. Those who have previously managed patients undergoing cataract surgery under topical anaesthesia are more likely to believe so compared to those who have not, suggesting the importance of experience in shaping one's opinions and beliefs. Anaesthesia providers who routinely counsel their patients were more likely to have been informed by previous patients that they have encountered such visual sensations or that these visual experiences were frightening. In the curricula of anaesthesia providers, it is important to highlight the facts on patients' potential visual sensations during cataract surgery as it has been shown that those who are aware of this are more likely to counsel their patients preoperatively.
The authors have not received any financial support for this study and have no financial or proprietary interests related to the contents of this manuscript.
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