Minimal anesthetic manual small-incision cataract surgery (MSICS): A novel technique in use for anesthesia in MSICS : Indian Journal of Ophthalmology

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Minimal anesthetic manual small-incision cataract surgery (MSICS): A novel technique in use for anesthesia in MSICS

Dev, Suvir; Bali, Jatinder1,; Narang, Surinder; Miglani, Sundeep; Arneja, Jaswant2

Author Information
Indian Journal of Ophthalmology 70(11):p 4029-4031, November 2022. | DOI: 10.4103/ijo.IJO_1335_22
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Abstract

Modern day cataract extraction techniques are evolving continuously as also are the techniques of administering ocular anesthesia. Retrobulbar and peribulbar anesthesia were used to give adequate anesthesia and analgesia to proceed safely with surgery. Due to complications like retrobulbar hemorrhage, globe perforation, and systemic absorption, a minimalistic approach for anesthesia in manual small-incision cataract surgery (MSICS) was explored.

Topical and intracameral anesthesia is common in modern day phacoemulsification cataract surgery involving clear corneal incisions. The authors here present a novel minimal anesthetic agent technique for MSICS. It is a combination of subconjunctival and intracameral anesthesia.

Cocaine was the first anesthetic used for ocular anesthesia by Jacob Hermann Knapp in 1884. Currently, a combination of lidocaine and bupivacaine is reported to be the most popular, as the short-acting lidocaine provides immediate anesthesia while bupivacaine provides longer duration of anesthesia.[1] Topical anesthetic, with the use of supplemental intracameral lidocaine, is the most commonly used method of anesthesia for cataract surgery in the US.[2] The upsides of this technique are that it does not alter vision, avoids the use of needles, and may not require sedation. The downside is that it does not provide akinesia, in that the eye is still under voluntary movement. Therefore, careful patient selection for this technique is paramount.[3] Intracameral anesthesia is used to supplement topical delivery to achieve better anesthesia.[34] Retrobulbar anesthesia is administered using a 32-mm-or-less needle inserted bevel up into the lower eyelid just above the orbital rim at the border between the lateral and middle third of the lower eyelid. The direction is backwards and then upwards tangential to the globe and into the muscle cone. The needle is inserted horizontally until the tip is judged to be posterior to the equator, at which point the needle tip is angled superiorly at 45° and slightly medially.[4] The globe is watched for any movement during needle insertion, which indicates scleral engagement and the attendant risk of puncturing the globe.[4] The anesthetic mixture is delivered after withdrawing the plunger slightly to look for blood to rule out entry into blood vessels. The peribulbar block uses similar preparation. The needle, however, is usually shorter than 25 mm and is advanced horizontally under the globe without the upward advancement. Larger volume of anesthetic (commonly 6–10 mL) makes up for the more distant delivery from the optic nerve sheath.[5] Edge found ocular injury rates of 0.007% for retrobulbar and 0.022% for peribulbar blocks.[6]

Sub-Tenon’s block is applied under Tenon’s capsule—the sheath that surrounds the eye from the optic nerve to the limbus and creates a potential space around the sclera.[7] An incision is made in the inferonasal quadrant of the sclera, through which is passed a blunt, curved cannula to deliver 3–5 mL of anesthetic into the episcleral space. Subconjunctival hemorrhage, a postoperative side effect that is transient and cosmetic, and the requirement of surgical tools that may not be readily available in outpatient day surgery locations have hindered its acceptance.[7] Perioperative complications include transient decrease in visual acuity after administration of local anesthetic, likely due to conduction blockade of the optic nerve or ischemia related to optic nerve compression. Patients should be warned about the possibility beforehand to minimize anxiety during the surgery. Permanent vision complications are the result of penetration of the globe, optic nerve, or central retinal artery. Brainstem anesthesia includes symptoms of difficulty breathing, dysphasia, hypertension, tachycardia, severe shivering, agitation, confusion, or unconsciousness generally occurring within a few minutes of anesthetic administration.[8] Supportive treatment is essential, including interventions to support respiration and stabilize blood pressure. The mechanism of action for brainstem anaesthesia is postulated to be a spread through the optic nerve sheath or foramina of the orbit.[89] Diplopia due to extraocular muscle injury occurs due to injection of anesthetic into a muscle sheath. Arterial and, less so, venous retrobulbar hemorrhage cause rapid orbital swelling, and increased intraocular pressure (IOP) may necessitate a canthotomy to reduce the IOP which should be monitored.[10] Topical anesthesia using 2% lignocaine with 0.5% intracameral lignocaine has been described but it has not been replicated by other investigators.[11] Similarly, a subconjunctival technique using a 25-gauge, 16-mm needle with up to 10 mL of lignocaine 2% plain or in equal mix with bupivacaine 0.5% in the conjunctiva and Tenon’s capsule in the superior outer quadrant of the globe with a posterior direction into the sub-Tenon’s space has also been described.[12] The authors evaluated a novel technique of minimal anesthesia for MSICS used by some practitioners but not described in literature and which has usually traditionally been performed by peribulbar and retrobulbar anesthesia. This technique is safe with a minimal learning curve and uses minimal anesthetic agent.

Surgical Technique

After paint and drape of the eye, a sterile surgical disposable drape is applied to the eye and a drop of topical anesthetic proparacaine is instilled into the cul-de-sac. Care is taken during application of drape to separate the lids and cover the lashes. A mixture of 1 mL of inj. lidocaine hydrochloride 2% w/v and 1 mL of inj. bupivacaine 0.5% w/v are taken in a 2 cc syringe and with the help of a 26-gauze needle running horizontally about 3–4 mm above the limbus. This mixture is injected into the bulbar subconjunctival space inserting the needle and injecting at 2 o’clock position and gradually withdrawing the needle until a bleb has been raised superiorly. A sterile bud/cotton-tipped applicator is taken and a gentle massage was given at the bleb site for even distribution of the mixture of local anesthetics.

Conjunctival peritomy is made with Castroviejo scissors to raise a fornix-based flap and blunt dissection of Tenon’s capsule is done to expose the main incision site for about 4 o’clock hours as shown in Fig. 1. Main scleral incision is made with a 15 no. blade 1–1.5 mm behind the limbus, and a crescent blade is used to dissect a self-sealing sclerocorneal tunnel. Dissecting at least 2–3 mm intracorneal with the inner corneal extent of the incision broader than the outer sclera extent of the incision to make it a trapezoid configuration. Two side ports are made at 3 o’clock and 9 o’clock meridians. Air is injected into the anterior chamber followed by injection of trypan blue dye 0.06% w/v underneath the air bubble to stain the anterior capsule of the lens. The dye is washed out with saline, and 2–3 mL of intracameral lidocaine hydrochloride 1% preservative-free is injected into the anterior chamber followed by injection of a cohesive viscoelastic. A bent needle cystotome is then introduced into the anterior chamber and a continuous curvilinear capsulorhexis is made.

F1
Figure 1:
Steps of technique (a and b) local anesthetic injection. (c and d) Surgical steps under intracameral lignocaine

The tunnel is opened with a 3.2-mm keratome with the usual dimple down technique. Excess viscoelastic is washed out. Hydrodissection is done. Nucleus is rotated and prolapsed in the anterior chamber and delivered via viscoexpression. Cortical material is washed out using a two-way irrigation aspiration Simcoe cannula. Viscoelastic is injected to inflate the capsular bag and a posterior chamber intraocular lens (IOL) is implanted and dialed into the capsular bag. Viscoelastic substance is removed using the Simcoe cannula and the anterior chamber is formed using saline. Both side ports are hydrated with saline to seal them up. The authors use intracameral moxifloxacin and a subconjunctival injection of gentamicin and dexamethasone into the superior conjunctiva so that the bleb formed adequately covers the main incision. The total quantity of anesthetic mixture used is about 3–3.5 mL. This method avoids the serious complications seen with peribulbar and retrobulbar blocks. The authors routinely counsel the patients about probability of a red eye after surgery as this can produce a concerned patient and an even more concerned family.

Modern day cataract surgery has evolved with minimalistic approach pertinent to surgical technique and mode and route of anesthesia for surgery. Using minimal anesthesia in the form of topical proparacaine, oxetacaine, and benzocaine with supplementation with intracameral preservative-free lidocaine has revolutionized the modern day cataract surgery, avoiding the untoward and unfortunate complications of peribulbar and retrobulbar anesthesia, though patient selection has been a major limiting factor. Topical and intracameral anesthesia has mainly been used for phacoemulsification cataract surgery involving smaller incisions usually clear corneal with minimal tissue manipulation. MSICS has traditionally been performed with peribulbar and retrobulbar anesthesia due to the need for more tissue manipulation compared to phacoemulsification cataract surgery. The minimal anesthetic approach has not been researched with MSICS even though the products are freely available and approved for use in cataract surgery.

Our method of performing MSICS with minimal anesthetic was found to be safe, pertinent to patient comfort, and avoided grave and undesirable complications secondary to systemic absorption of anesthetic agents. It gave adequate analgesia and anesthesia to complete the surgery. Superficial injection of a small amount of anesthetic also avoided direct injury to optic nerve which is a risk in peribulbar anesthesia and is a common occurrence in retrobulbar anesthesia.

Conclusion

We conclude that even in MSICS, a minimalistic anesthetic approach can be used that nearly matches the topical mode of delivering anesthesia in phacoemulsification cataract surgery. Tis technique has enhanced safety and avoids usual complications of traditional peribulbar and retrobulbar anesthesia. In uncooperative patients small amount of supplemental anesthesia in the form of peribulbar injection or sub-Tenon’s injection was needed. This makes patient selection an important consideration while contemplating it just like topical anaesthesia. Patient selection an important consideration while contemplating it.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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Keywords:

Intracameral anesthesia; manual small-incision cataract surgery; subconjunctival anesthetic approach; surface anesthesia

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