Spanish ophthalmologist Francisco J Gutiérrez-Carmona MD, PhD presented the results of a randomised, comparative study he performed with Jorge Alvarez-Marín MD, PhD.
The study included 82 eyes of 82 patients and, with very few exceptions, found no significant differences between the groups in operative length, incidence of complications, patient reported levels of pain, physiological responses or surgeon intraoperative comfort during various steps of the surgery.

The two study groups were well balanced for age, gender and nuclear density. The protocol excluded patients deemed unco-operative or who had difficulty expressing their pain level using a rating scale. Also excluded were monocular patients and those with hypermature cataracts, narrow anterior chambers or those who achieved pharmacological mydriasis of less than 5.0 mm.

The topical anaesthesia group received two drops of a mixture of 1% tetracaine hydrochloride and 4% oxybuprocaine hydrochloride three times beginning 10 to 15 minutes before surgery.

Patients in the cryoanalgesia group received two drops of BSS preoperatively according to the same regimen. In both groups, cold (4ºC) BSS was used to irrigate the ocular surface throughout surgery. Patients did not receive sedatives preoperatively or any non-steroidal anti-inflammatory drops.

Physiological responses to surgical stress, evaluated by monitoring heart rate and blood pressure, showed no significant differences between groups throughout surgery.

However, maximum blood pressure was significantly higher at the time of corneal incision hydration in the cryoanalgesia group, while two patients in the topical anaesthesia group required anti-hypertensive treatment, Dr Gutiérrez-Carmona noted.

Using a four-point scale, where 0=none, 1= little, 2=some and 3=much, patients were asked to rate their pain at each of the following phases of surgery: speculum insertion, paracentesis, corneal incision, CCC, hydrodissection, phacoemulsification, cortex aspiration, IOL implantation, and incisional stromal hydration, as well as at 24 hours postoperatively.

In both groups, paracentesis, corneal incision and IOL implantation were the most painful steps, but the mean pain scores at those steps were just 1 or slightly higher.
The only statistically significant difference between groups was observed during paracentesis, when patients operated on under cryoanalgesia reported significantly more pain than their counterparts in the topical anesthesia group.

Nevertheless, the mean pain score in the cryoanalgesia group was less than 0.5. One patient in the topical anaesthesia group required intraoperative sedation.
The study also investigated the surgeon’s perspective on comfort during the various steps of the procedure. There were no statistically significant between-group differences in surgeon stress at any stage, or in the overall evaluation.

Patient satisfaction was high in both study groups with 40 (95.2%) patients in the cryoanalgesia group and 39 (97.5%) patients in the topical anaesthesia group indicating they would undergo the same surgical technique again.

Three patients in the study underwent bilateral surgery with cryoanalgesia in one eye and topical anaesthesia in the fellow eye. Two of those patients indicated a preference for cryoanalgesia.

Not only was the cryoanalgesia well tolerated by the patients, but the technique has a number of potential advantages compared with topical anaesthesia, Dr Gutiérrez-Carmona said.

“We have found that cryoanalgesia can be a very useful technique, although just as with surgery performed under topical anesthesia, one needs to select patients carefully based on their expected level of co-operation.

“Not only does cryoanalgesia allow us to operate comfortably on patients who are allergic to anaesthetics, but it may also improve postoperative outcomes. With cryoanalgesia there is no exposure to medications and the cold irrigation might help reduce postoperative inflammation by diminishing uveal sanguineous flow and stabilising the blood-aqueous barrier,” he said.

It may also minimise endothelial trauma from the heat of the phaco tip and the low temperature environment might inhibit the growth of bacteria which could contribute to endophthalmitis, Dr Gutiérrez-Carmona added. He said he and his team hope to study these benefits further in the future.
German specialist, Tobias H Neuhann MD, agrees that no-anaesthesia cataract surgery, facilitated by the use of cold fluids, is a valuable technique. He said it is particularly useful in older patients who have a large arcus senilis and who understand that the surgery will not be sensation-free.

Unlike Dr Gutiérrez-Carmona, Dr Neuhann does not offer this alternative approach routinely to his cataract surgery patients. But he said he has found it has a definite place for patients who are allergic to ‘caine’ type anaesthetics as well as for those opposed to medication use, either because they have a drug phobia, a distrust of medications or are strong believers in their body’s self-healing potential.

“When I first heard of no-anaesthesia cataract surgery, I didn’t believe it was possible. However, I was convinced otherwise after watching Amit Agarwal MD operate. I am not discussing it routinely with patients because considering the culture of older, German patients, I expect most would reject the idea of surgery without anaesthesia.
“However, I have found there is a niche for this technique, both for patients who need it and those who seek it. Rather than trying to argue and convince the latter patients to have topical anaesthesia, I am prepared to offer a no-anaesthesia procedure and that makes my life as a surgeon easier,” Dr Neuhann said.

Dr Gutiérrez-Carmona is currently searching for a laboratory which will manufacture a viscoelastic material capable of maintaining a cold temperature for a longer period.
Dr Neuhann noted that he favors Healon 5 (Pharmacia) as his viscoelastic of choice for the no-anaesthesia procedures because it enhances chamber stability and protects sensitive ocular tissues.

“When operating without an anaesthetic, it is important to perform phaco very carefully to avoid excessive pressure fluctuation which can cause pain. Healon 5 helps to minimise those events and also perfectly protects the cornea and iris,” he explained.
Dr Gutiérrez-Carmona first introduced this strategy in 1999 as a variation of the no-anaesthesia technique developed by Dr Agarwal. Dr Gutiérrez-Carmona says he now offers the cryo option to any patient he deems a candidate for topical anaesthesia and has found it is associated with high patient acceptance.

Basics of cryoanalgesia WHEN performing cryoanalgesia, Dr Gutiérrez-Carmona cools all the surgical fluids, except povidone, to approximately 40C. He also cools the eye first by applying a gel-containing mask for 10 minutes to reduce lid sensitivity and facilitate insertion of the lid speculum. Cold methylcellululose is instilled in the eye after placement of 5% povidone drops to reduce the stinging sensation caused by the antiseptic agent. Next, the eye is irrigated with cool BSS prior to create the paracentesis. A cool, high-density viscoelastic is injected into the anterior chamber and a clear cornea incision is made using a 3.2mm phaco knife, while the ocular surface is cooled with BSS and the eye stabilised using a lens manipulator or spatula. This surgery must be performed only through a clear corneal incision and touching the conjunctiva or sclera, as well as using forceps to stabilise the eye, must be avoided. Dr Gutiérrez-Carmona uses either a Barraquer speculum or Castroviejo speculum for blepharostaxis. The capsulorhexis is performed with a capsular forceps and the nucleus hydrodissected using cold BSS. Phaco of the nucleus is performed using a cooled irrigating solution. If higher phaco energy is being used when operating on a hard nucleus, some patients may complain of pain. In that situation, it may be necessary to decrease the ultrasound power. The cornea is also cooled before enlarging the incision for implantation of a foldable IOL. Some patients will develop increased blinking in response to the ongoing application of the cool BSS onto the eye. That reaction is not very common and usually does not interfere with the surgery. If necessary, the frequency of the instillation can be decreased and a Castroviejo speculum inserted, or BSS can be substituted with cold methylcellulose. If the surgery is prolonged and the temperature of the BSS or irrigating solution is rising, the flasks should be changed.