Anterior segment surgical procedures encompass, for the most part, the use of the anterior chamber space for various surgical manipulations, repair of traumatized ocular tissues, and the introduction of various prosthetic devices to restore anatomic integrity and/or to remove and replace structures, all in an attempt to improve globe functionality and augment the eyesight of the patient.
The anterior chamber space, which is filled with aqueous humor, is bounded by the inner corneal surface that is lined by the endothelium anteriorly, the trabecular meshwork and angle structures peripherally and the anterior surface of the iris tissue posteriorly. Collapse of the anterior chamber space during surgery can potentially result in endothelial cell damage by inadvertent mechanical trauma by the surgical instruments or in iris tissue damage with secondary bleeding into the chamber; in addition, angle structures may be damaged.
In 1987, Blumenthal introduced a novel innovation, the anterior chamber maintainer, which provided a high-pressure, high-flow system that would help maintain the anterior chamber space during anterior segment surgery, hence protecting the important tissue structures in this region of the globe and preventing potential iatrogenic damage. The anterior chamber maintainer continued to gain in popularity and has been used in various procedures including cataract surgery, anterior vitrectomy, IOL-related procedures and corneal procedures; it can also be used to decrease and/or eliminate the need for viscoelastic in select cases or used as a cost-containment approach. Another advancement is the use of transconjunctival sutureless vitrectomy trocars for posterior segment surgery. When inserted into the cannula, the trocar forms a continuous bevel that can then be withdrawn.
In this column, Drs. Agarwal and Narang describe their trocar anterior chamber maintainer for various anterior segment surgical procedures.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
Continuous infusion into the eye is often imperative for performing an intraocular surgery. An anterior chamber maintainer (ACM) and trocar cannula system form an essential component of surgery and are commonly employed. A trocar anterior chamber maintainer (T-ACM) is a new technique in which a trocar cannula system is used for infusion into the eye at the level of limbus, and it essentially works as an ACM. The basis for the wound construction is similar to the modern vitrectomy surgery, which creates a biplanar angle-based incision with the trocar system.
This procedure is done under peri-bulbar anesthesia, taking care to prevent any subconjunctival accumulation of the local anesthetic agent, which can lead to ballooning of the conjunctiva.
A biplanar incision is created for the introduction of the T-ACM. At 0.5 mm away from the limbus (Figure 1), conFjunctival displacement is done (Figure 2) and a 23- or 25-gauge trocar is introduced obliquely. The direction of trocar is changed, it is directed 90° to the limbus toward the center of the globe, and it is introduced inside the anterior chamber in front of iris tissue (Figure 3). The trocar is removed, and the infusion line is attached to the hub of the cannula, which has a threaded portion to lock and prevent any accidental slippage or loosening of the infusion line (Figure 4).
At the end of surgery, the cannula is held by forceps and it is withdrawn along the direction of the scleral tunnel. The conjunctiva is pressed with a cotton wool applicator, and sustained pressure is applied for few seconds to allow self-apposition of the sclerotomy wound.
A trocar cannula system is an indispensable tool for transconjunctival sutureless vitrectomy and other posterior segment procedures. A similar status is enjoyed by an ACM for the performance of an anterior segment surgery that necessitates infusion in the eye. The concept behind using a T-ACM is to provide a stable self-sealing wound, unlike an ACM.
In this procedure, we advocate the use of a 23- or 25-gauge trocar because angled incisions are reported to have minimal incidence of wound leakage compared with straight incisions. The advantages of using a T-ACM are faster recovery, less invasiveness and reduction in surgery-induced astigmatism. In addition, a T-ACM allows air-fluid infusion into the eye, which can be of great help during endothelial keratoplasty procedures (Figures 5 and 6). It can also be employed for handling various other complicated intraocular procedures (Figures 7 and 8), and the use of a T-ACM abolishes and obviates the need to use viscoelastic in the eye. The issue of spontaneous expulsion of the infusion cannula due to large wound size as seen with an ACM is not reported with a T-ACM because the incisions are valvular and they snugly fit the trocar cannula. Moreover, with a T-ACM there is less overcrowding of the corneal surface and more working space is available to the surgeon.
OCT study of these incisions demonstrated proper wound apposition and stability that completely healed at the period of 1 month.
To conclude, a T-ACM is effective in obtaining better wound closure and results in a significantly lower incidence of postoperative hypotony. However, a certain level of skill is necessary to make these tunnel-based incisions. The sclerotomy wound should be checked thoroughly, and in case of any persistent leakage noted from the sclerotomy site, the scleral wound should be sutured to prevent any overt hypotony.
Another disadvantage that can be associated with this technique is the occurrence of subconjunctival hemorrhage, which can occur due to disruption of conjunctival blood vessels during the insertion or removal of the T-ACM. Withholding the intake of aspirin or anticoagulants by patients before the operation, along with gentle maneuvering of tissues, might help decrease the risk of this complication.
- Blumenthal M, et al. J Cataract Refract Surg. 1987;doi:10.1016/S0886-3350(87)80137-2.
- Chen G, et al. Eur J Ophthalmol. 2015;doi:10.5301/ejo.5000537.
- Qazi ZU, et al. J Cataract Refract Surg. 2013;doi:10.1016/j.jcrs.2013.02.022.
- Simanjuntak GW, et al. Semin Ophthalmol. 2012;doi:10.3109/08820538.2011.622333.
- Vandewalle E, et al. J Glaucoma. 2014;doi:10.1097/IJG.0b013e318269806a.
- Wang Y, et al. Curr Eye Res. 2011;doi:10.3109/02713683.2010.543498.
- For more information:
- Amar Agarwal, MS, FRCS, FRCOphth, can be reached at Dr. Agarwal’s Eye Hospital, 19 Cathedral Road, Chennai 600086, India; email: email@example.com.
- Priya Narang, MS, can be reached at Narang Eye Care & Laser Centre, Ahmedabad, India; email: firstname.lastname@example.org.
- Edited by Thomas “TJ” John, MD, a clinical associate professor at Loyola University at Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at email@example.com.
Disclosures: Agarwal, Narang and John report no relevant financial disclosures.