Cryoanalgesia is an alternative for cataract surgery

February 15, 2001

Local anesthetics in cataract surgery have superseded general anesthesia due to their indisputable advantages, such as the potential for ambulatory surgery, rapid recovery and lack of complications.

However, local anesthetic surgery using the retrobulbar or peribulbar technique is not without possible complications, such as perforation of the eyeball accompanied by retinal detachment and severe intraocular hemorrhage, retrobulbar hematoma, diplopia, direct optic nerve trauma caused by the retrobulbar needle, increased intraocular pressure, postoperative ptosis, or systemic complications such as accidental administration of anesthetic to the bloodstream or nervous system.

---A monolateral eye mask of cold gel is placed over the eye before surgery for about 10 minutes.

The use of small-incision cataract surgery techniques involving manual phacofragmentation or phacoemulsification has prompted the reintroduction of topical anesthesia, first proposed by Hirschberg in 1910, who routinely operated on cataracts using a 2% cocaine solution. Smith in 1985 used a combination of topical anesthesia and subconjunctival injection of lidocaine for extracapsular cataract extraction. Fichman first reintroduced topical anesthesia for cataract surgery through phaco and the implantation of an IOL in 1992.

This was followed by the first cataract operation without pharmacological anesthesia performed by Agarwal in June 1998 at a live surgical conference in Ahmedabad, India. In February 1999, Gutiérrez-Carmona in Spain performed the first cataract operation using cryoanalgesia, modifying Agarwal’s method.

Surgical technique

---Anterior chamber is entered using a 3.2-mm phaco knife while the cornea is cooled with saline.

To perform surgery with cryoanalgesia, all solutions to be instilled during the operation (except povidone drops) are cooled to around 4° C.

Before surgery, a mask of cold gel is placed over the eye for about 10 minutes. This affords some degree of analgesia to the eyelids and permits insertion of the lid speculum.

Ocular asepsia before surgery is achieved using 5% povidone drops, then a drop of cold methylcellulose is instilled in the eye before placement of the ophthalmic drape to isolate the eyelid. This reduces the stinging sensation of the povidone.

It is important to perform phaco through a clear corneal incision and to avoid touching the conjunctiva or sclera and the forceps used to hold the eyeball. A Barraquer speculum is used for blepharostasis, although a Castroviejo speculum may also prove useful for this purpose.

Also, as with topical anesthesia, we need a reasonable level of patient collaboration.

Paracentesis

The cornea is cooled ahead of time by continuous irrigation from a flask of cold balanced saline solution in the area where paracentesis will be conducted. To perform paracentesis, the eyeball is held still with a spatula or lens manipulator placed on the corneal periphery, opposite where the anterior chamber (AC) is accessed using a paracentesis knife.

Clear corneal incision

Cold viscoelastic is injected through the paracentesis into the AC, and a lens manipulator is introduced to stabilize the eyeball. The cornea is continuously cooled with saline in the area where the clear corneal incision is to be made. A corneal tunnel incision is performed at 90° to the paracentesis with the help of a 45° stab incision knife, an angled crescent knife and a 3.2-mm phaco knife.

Capsulorrhexis, nuclear phaco

---The cornea is cooled in the area of the paracentesis.

Cold viscoelastic is injected into the AC, then the corneal incision is chilled in order to perform a continuous circular capsulorrhexis with capsular forceps. The lens nucleus is hydrodissected with cold saline irrigation using a Binkhorst or a straight Rycroft cannula, inserted at 12 o’clock.

Depending on the surgeon’s preference, our method can accommodate the use of a peristaltic pump or venturi pump system.

The phaco process may be performed using any surgical technique: chip and flip, divide and conquer, chop, etc., modifying the settings of the machine according to the type of cataract, type of machine and surgeon’s preference. We prefer phaco with cold saline irrigation during linear and pulsed phaco.

During phaco, the cornea must be kept chilled with saline. When the phaco tip is inserted into the anterior chamber, the corneal incision is cooled by continuous irrigation from a flask of saline.

Cortical aspiration

Cortical aspiration is performed with cold irrigation according to the settings of the surgeon’s phaco machine.

IOL implantation and incision closure

Cold viscoelastic is injected into the capsular bag, and the corneal incision is extended to 4.1 mm after chilling. Once the corneal incision is cooled with saline, a foldable IOL is implanted. Closure of the incision is performed by stromal hydration using cold saline solution.

Comments

In February 1999 I was invited to perform live cataract surgery in the Asian Cataract and Refractive Surgery Convention in Bangalore, India. Surgeons attending this meeting were surprised to see Dr. Amar Agarwal perform live cataract surgery without anesthesia.

Back in Spain I tried his technique, with modifications whereby the surgery was carried out using cryoanalgesia. The advantage of performing phaco with irrigation at low temperature is that it partially avoids the heat generated by the phaco tip, eliminating pain.

Further, using cold fluids reduces postop inflammation, the risk of endophthalmitis and the endothelial trauma caused by the heat of the phaco tip.

Cryoanalgesia has successfully been used in thoracic surgery for lung lobectomy through a minithoracotomy, and in the treatment of postop pain following thoracotomy, hip adductor spasticity and obturator neuralgia. It has also been used in plastic surgery and dermatology.

With this new method, it is important to emphasize continuous cooling by irrigation of the corneal surface before performing paracentesis and corneal incision, and before introducing any instrument into the anterior chamber.

The analgesic effects of cold have long since been known, although the physiological basis remains unclear. A possible explanation, based on the lack of functional specificity of somesthesic receptors, is saturation of the receptor-nerve fiber complex induced by an initial stimulus, in this case cold, such that the response to other sensations conveyed by identical nerve fibers (pain or pressure) is blocked while the initial stimulus is maintained.

The authors are currently evaluating the ideal level of analgesia for maximum patient comfort during surgery and postop period, and surgeon comfort when performing phaco. We emphasize the surprising tolerance found in the majority of patients who undergo this new method.

For Your Information:

• Francisco J. Gutiérrez-Carmona, MD, PhD, a former fellow of Ramón Castroviejo, MD, can be reached at the department of ophthalmology of Hospital Riunón y Cajal, Carretera de Colmenar Viejo, Km 9.100.28034, Madrid, Spain; private fax: (34) 921-480270; e-mail: fjgutierrez@interbooknet.
• Maria T. lradier, MD, PhD, is an anterior segment surgery specialist at the department of ophthalmology of Hospital Clinico Universitario de San Carlos, Madrid, Spain; e-mail: irago@telcom.es.
• José A. Gegúndez, MD, PhD; Madrid, Spain; e-mail: jgegundez@wanadoo.es. Dr. Gutiérrez-Carmona, Dra. Iradier and Dr. Gegúndez have no direct financial interest in the products mentioned in this article, nor are they paid consultants for any companies mentioned in this article.

References:

• Agarwal A, Agarwal S, et al. No anesthesia cataract surgery with karate chop. In Phacoemulsification Laser Cataract Surgery and Foldable IOLs. Jaypee Brothers, New Delhi 1998; 19:144-154.
• Gutierrez-Carmona FJ. Phacoemulsification with Cryoanalgesia: A New Approach for Cataract Surgery. In Phacoemulsification, Laser Cataract Surgery and Foldable IOLs. Jaypee Brothers Medical Publishers (2nd ed), New Delhi, 2000; 23:226-229.
• Tovar EA, Roethe RA, et al. One-day admission for lung lobectomy — an incidental result of a clinical pathway. Ann Thorac Surg 1998; 65(3): 803-806.
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• Pastor J, Morales P, et al. Evaluation of intercostal cryoanalgesia versus conventional analgesia in postthoracotomy pain. Respiration 1996;63(4):241-145.
• Kim PS, Ferrante FM. Cryoanalgesia — A novel treatment for hip adductor spasticity and obturator neuralgia. Anesthesiology 1998;89(2):534-536.
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