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A comparison of methods of local anaesthesia used for cataract extraction.


Over the last 10 years there has been a major change in anaesthetic practice for the majority of ophthalmic surgical patients (Thampy, Hariprasad & Saha 2007). The change is that most procedures are now done under LA. This is due to major advances in every aspect of the management of the ophthalmic surgical patient plus:

* The pressure to perform surgical procedures as day case.

* Increased focus on the patient.

* The involvement of the entire ophthalmic team (Forest & Johnson 2007).

The goals of any type of LA for ophthalmic surgery are the same:

* To provide pain free surgery.

* To minimise risks of systemic complications.

* To facilitate the surgical procedure.

* To reduce the risk of surgical complications (Forest & Johnson 2007).

Also the general issues, which are assessed at the preoperative clinic, are the same:

* The patients' suitability for day surgery.

* The patients' overall condition.

* Their ability to lie flat.

* Their ability to comply with instructions (Gordon 2006).

Peribulbar block

For many years the traditional block used for ophthalmic surgery was the retrobulbar block, when LA was placed deep within the orbit of the eye, using a long needle. By definition, this was a risky procedure and a number of modifications were employed, one of which was the peribulbar block (Hamilton 1995).

During a peribulbar block, following topical LA, and with the patient looking straight ahead, the LA is injected inferotemporally using a 16mm 25g needle. Due to the technique used, and the shorter needle, the tip of the needle remains in the peribulbar space, and so the optic nerve is protected. Following aspiration, 5-10 mls of LA is injected. Light pressure is then applied to the eye, and muscle movements can be tested after five minutes (Kumar, Dodds & Fanning 2002).

Peribulbar anaesthesia can only be administered if there is an anaesthetist and an operating department practitioner present (Royal College of Ophthalmologists and Royal College of Anaesthetists (RCO and RCA) 2001).

Usually the peribulbar solution consists of a combination of the following:

* Bupivicaine 0.5 or 0.75% (slow acting).

* 2% lidocaine, with or without adrenaline (fast acting).

* Hyaluranidase (to improve diffusion and prolong duration).

This combination is used to facilitate a more rapid onset and to ensure that it is effective for the duration of the operation, but for a peribulbar block to be fully effective there should be a delay of 15 minutes to give the LA time to reach its site of action (Varvinski & Eltringham 1996).


As with any procedure where there is interstitial injection, there is always the risk of anaphylaxis, and so resuscitation facilities must be available (Rubin 1995).

Complications specific to regional anaesthesia could be the result of the agent used, or to the actual technique.

Complications of agent

* If the LA is injected into the cerebrospinal fluid within a cuff of dura around the optic nerve, this could cause immediate cardio vascular and respiratory collapse.

* If the LA is injected intravascularly, this could also cause cardio vascular and respiratory collapse, but not so rapidly.

* Systemic toxicity may occur if there is an overdose of LA or of the adrenaline, which may be added to the LA.

* Allergic reaction to hyaluronidase (Peck, Hill & Williams 2003).

Complication of technique

Hopefully a comprehensive preoperative assessment will have already eliminated unsuitable patients, and established some rapport with the patient, which should reduce anxiety and improve compliance, and so reduce the risks (Gordon 2006).

* Retrobulbar haemorrhage--this is serious but very rare.

* Subconjunctival oedema (chemosis).

* Penetration or perforation of the globe.

These are all more likely in myopic eyes, in uncooperative patients and are avoided by extensive knowledge of the orbital anatomy (Rubin 1995).

sub-Tenons block

Just as the peribulbar block evolved due to the high risks of complications of the retrobulbar, so the sub-Tenons block has become increasingly popular in recent years, in an effort to reduce the incidence of complications from sharp needles (Ruschen, Bremner & Carr 2003). It also has advantages for myopic and anti-coagulated patients.

During a sub-Tenons, or episcleral block, LA is instilled into the lower fornix. A speculum is inserted to hold the eye open, and the conjunctiva and Tenon's capsule are incised. A blunt, curved 19g 25mm sub-Tenons cannula is advanced into the inferonasal quadrant and the LA is delivered posterior to the equator of the globe (Hamilton 1995).

The sub-Tenons technique can be used without an anaesthetist being present, and the LA given is chosen by the surgeon, but usually 3-4 mls of 2% lidocaine is sufficient to give reliable anaesthesia and sub-total akinesia (Hamilton 1995). Onset of anaesthesia is rapid, usually within five minutes.



Although sub-Tenons blocks generally have fewer complications, they are still present. Those as a result of the agent are the same as listed above, and others are due to the technique:

* Chemosis--caused by sub-conjuntival placement of the LA.

* Severe orbital cellulitis--this is very rare.

* Rectus muscle trauma, resulting in postoperative diplopia.

* Globe perforation with the scissors (Ruschen, Bremner & Carr 2003).

Topical Anaesthesia

The evolution of ophthalmic anaesthesia continues with the fairly recent introduction of surgery using topical anaesthesia only (Srinivasan et al 2004). During this type of anaesthesia there is no akinesia, and so patient selection and compliance is crucial (Lowe et al 1992).

If the operation is to be done using topical anaesthesia only, this is administered once the patient is positioned on the operating table. The drug is chosen by the surgeon and is usually one, or a combination of:

* Proxemethacaine 0.5%

* Oxybuprocaine hydrochlor 0.4%

* Tetracaine hydrochlor 1% (Hopkins & Pearson 2007)

A variation of the topical anaesthesia is to use it in conjunction with intracameral anaesthesia, which is administered during hydrodissection of the lens. During this technique a solution of 0.5-1% lidocaine is used (Roberts & Boytell 2002).


As there is no interstitial injection of any substance the risk of systemic complications are minimal. Also there are obviously no complications from penetrating or traumatic injuries during instillation. The only documented complication is that of clouding of the cornea and irritation as the drops are administered (Rubin 1995). Onset of anaesthesia is rapid: 30-60 seconds.


Ideally the ophthalmic patient should be fully conscious and not too anxious, and this can usually be achieved by a sensitive and responsive ophthalmic team, and continuity of practitioner contact.

If it is decided to give sedation an anaesthetist and practitioner must be available, as should non-invasive monitoring. The patient is booked for day surgery with a bed. The aim of the sedation is to relieve anxiety, but not for the patient to fall asleep. Given that there is a marked difference in the effects of sedation in different people, especially the elderly, it should be given with caution, and with a rapid recovery (AAGBI 2000).

The sedative is chosen by the anaesthetist and is usually one of the following: midazolam, ketamine, alfentanil or proprofol (Habib, Balmer & Hocking 2002).


These are similar for any form of sedation and include restlessness, sudden movement and airway obstruction. If the patient becomes unresponsive to commands, they are no longer sedated, but have become anaesthetised with all of those inherent risks.

Another problem with all of the sedatives except proprofol is the long sedative tail, which can cause the patient to fall asleep, and sudden movement on waking (Peck, Hill & Williams 2003).


Education and stress

The usual treatment given to reduce patients' anxiety is sedation. However, it has long been understood that knowledge and understanding also reduce stress levels in any situation, none more so than for day surgery. Mitchell (2002) emphasises the need for preoperative information to be managed effectively so that it reduces stress and does not add to it. An ideal time for the patient to be given this information would be during the preoperative assessment. As most of the preoperative assessments are done by the nurses, it is crucial that they have the necessary skills and knowledge to impart this information accurately, in a manner that will reassure the patient and not make them more anxious (Marsden 2006). If time was spent during this preoperative assessment to try and educate the patients about the procedure, this in itself is likely to reduce their stress level and the need for sedation (Stollery, Shaw & Lee 2005).

Having continuity of care by a small group of highly skilled practitioners can also add to the patient's confidence and again further reduce patients' anxiety and so the need for sedation. For any procedure to be done under LA, patient involvement and cooperation are crucial, which can be less reliable following sedation (Forest & Johnson 2007).


From the literature it appears that sedation is also given to overcome the patients' fears of the peribulbar block, not the operation itself. Habib, Balmer and Hocking (2002) observed that some patients were concerned about the proximity of the needle to the eye while the peribulbar block was given, and this was the reason for the sedation to be given. The use of sub-Tenons or topical anaesthesia alone would therefore negate any reason to give sedation. The RCO and RCA (2001) guidelines also state that sedation should not be given to cover for inadequate blocks.

During their discussion about intravenous (IV) sedation during surgery Wong and Merrick (1996) suggested that the most unpleasant memory for most patients is the pain when the needle used to deliver the peribulbar is inserted, or the discomfort during the injection of the anaesthetic solution. For their study, either oral or IV sedation was given before the peribulbar block, to minimise the pain associated with it, which the study supported. However, in the author's opinion, if the sedation is given IV, then there will already have been the pain associated with having a cannula inserted, which is not mentioned, and if a different method of anaesthesia was chosen, the anxiety could have been prevented altogether.

Additionally, in the author's own recent experience, a patient refused to have her second eye operated on because of the peribulbar anaesthetic she was given for the first eye. It was only following reassurance that a different form of anaesthesia would be used, that she agreed to have it done.

Katz et al (2000) also investigated patients' perceptions with topical alone, or peribulbar, with or without sedation. They concluded that patients' reports of pain were low--5%, but did not differentiate for each type of anaesthetic used. Interestingly they also identified the other postoperative side effects of sedation: drowsiness, nausea and vomiting, which are not frequently mentioned.

Patient Satisfaction

The advantages of sub-Tenons or topical are also supported by Zafirakis, Voudouri and Rowe (2001), whose study was originally to compare these two methods against each other, but concluded that they both gave good results, and high levels or satisfaction, with sub-Tenons giving slightly better pain relief, and topical having fewer complications.

As stated, the peribulbar block evolved as a safer alternative to the retrobulbar block, which gave similar results of anaesthesia and akinesia. Kumar and Dodds (2006) suggest that complete akinesia is not essential for modern cataract surgery, even though some surgeons may still prefer it. Other surgeons welcoming the fact that the patient can move their eye when instructed to do so (Navaleza, Pendse & Blecher 2006). Additionally, the effectiveness of the peribulbar block is dependent on the skills of the anaesthetist and does not always guarantee complete akinesia. Again, in the author's own experience, the number of anaesthetists skilled in administering peribulbar anaesthesia are diminishing.

The use of sub-Tenons anaesthesia was discussed by Tasneem et al (2005) who concluded that it was as effective as peribulbar with no significant increase in complications and yet more comfortable for the patients during administration. This is endorsed by Allen (2007) who describes it as a very safe and reliable form of anaesthesia, which is rapidly becoming the ophthalmic anaesthetic of choice.

The use of this form of anaesthesia could also be tempting for trusts keen to reduce their budget, as the RCO and RCA (2001) states that if a peribulbar technique is to be used, there should be an anaesthetist present, but not for a sub-Tenons block.

However, this could also be the reason why some surgeons still choose to use peribulbar blocks. By having an anaesthetist present, it shares the burden of responsibility, for example, in a situation of sudden cardiovascular collapse.

In the author's own experience, topical anaesthesia alone with intracameral lidocaine is the one most frequently given, however, there is little evidence to support this. Srinivasan, Fern Selvaraj and Hasan (2004) concluded that patients who had topical anaesthesia only, suffered more postoperative pain than with a sub-Tenons block, and Johnston et al (1998) agreed with this, saying that patients had a greater awareness of ocular discomfort. However, they also said that it did not alter their levels of satisfaction. Additionally, Virtanan and Huha (1998) stated that for patients who had received topical anaesthesia only, the level of pain felt during actual surgery was greater, but no different from the pain felt by others during the administration of the peribulbar block.


Hopkins and Schein (2001) summarised by saying that there remains uncertainty about which type of anaesthetic provides the best mixture of patient comfort, surgical outcome and freedom from anaesthetic related complications. The indications are that they are all safe and effective and that no single technique is more so than the others.

Topical anaesthesia does not provide complete relief of pain as do various injection techniques, but there is comparatively less anxiety and discomfort during instillation, and it avoids many of the complications of peribulbar blocks (Kallio, Uusitalo & Maunuksela 2001). It is also quick and easy to administer by the theatre staff, which may have influenced it's popularity for some surgeons.

sub-Tenons does not usually cause the patient anxiety or discomfort and gives good anaesthesia, but does not guarantee akinesia. Whereas peribulbar, although causing some anxiety to patients, ensures the best surgical outcome (Habib, Balmer & Hocking 2002).

The choice of which type of anaesthetic to use should be influenced by many factors:

* The surgeons' preference.

* The anaesthetists' preference

* The patients' character (Navaleza, Pendse & Blecher 2006).

However, in the author's opinion, it is usually the surgeons' preference which takes priority.

Interestingly, Hopkins and Schein (2001) suggested that bringing the patients' perspective into the discussion of what creates the optimal ophthalmic anaesthesia would be helpful, and yet this aspect is rarely considered.


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Suki Studholme


Ophthalmic Theatre Sister, University Hospital Birmingham
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Author:Studholme, Suki
Publication:Journal of Perioperative Practice
Geographic Code:4EUUK
Date:Jan 1, 2008
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