Eyes with an altered anterior chamber as a result of ocular trauma, iritis, or iridocyclitis are prone to developing synechiae. Inflammation from infection or surgery can also trigger formation of these fibrous adhesions of ocular tissue, which may not necessarily be visible unless viewed at the slit lamp. Regardless of their cause, extensive posterior synechiae can impede pupillary dilation during cataract surgery.
Mydriatic or cycloplegic agents such as atropine can be used to break up mild synechiae, dilate the pupil, and keep the iris from touching the crystalline lens. However, long-established or strongly adherent synechiae may not be manageable in this manner and may resist pharmacologic dilation at the beginning of surgery. If this is the case, synechiolysis can be used to break up the adhesions and allow pupil dilation for better visualization of ocular structures and ease of surgical maneuvers.
I have devised a strategy for use in patients who present for cataract surgery with small pupils due to stubborn, membranous synechiae. In this technique, which I call synechiarrhexis, capsulorrhexis forceps are used to tear out and remove the synechial membrane, in a manner similar to performing capsulorrhexis, before continuing with cataract surgery. Analogous to the difference between capsulorrhexis and the can-opener capsulotomy technique, synechiarrhexis simplifies and streamlines the procedure, accomplishing the removal of synechiae with a continuous motion rather than numerous interrupted synechiolysis maneuvers.
I have performed synechiarrhexis in approximately 100 cases. A video of one of my recent cases is posted online at eyetube.net/?v=goonez. This patient had a dense cataract and a small pupil due to synechiae.
In cases with small pupils and synechiae, after creating a 2.2-mm incision and instilling trypan blue dye under the iris to stain the capsule, I inflate the anterior chamber with a dispersive-cohesive ophthalmic viscosurgical device (OVD) such as DisCoVisc (Alcon Laboratories, Inc.). With adequate space in the anterior chamber, I am now able to perform the following maneuvers safely.
Synechiarrhexis. Using the capsulorrhexis forceps in a manner similar to capsulotomy, I catch the edge of the synechial membrane (Figure 1A) and perform the synechiarrhexis with a circular motion (Figure 1B). After using controlled movements to complete the synechiarrhexis 360º, I can then remove the membrane through the incision (Figure 1C).
Pupil dilation. With the synechiae now resolved, I turn my attention to dilating the pupil. Eyes with small pupils are always surgically challenging, even when synechiae are not present. Pharmacologic approaches such as intracameral or topical mydriatics can be helpful in managing a small pupil during cataract surgery; however, they have limitations and often insufficiently dilate the pupil. In such cases, mechanical stretching, cutting, or iris retraction can be used. I prefer to dilate the pupil mechanically during surgery when necessary. Surgeons with different skill levels and preferences may use another technique.
In the first step, I inject DisCoVisc at the level of the pupil. Injecting the OVD in a circular motion is usually sufficient to enlarge the pupil; however, in the case shown in the video, the OVD was not enough, and I chose to perform an iris stretch technique. Micromanipulators, inserted through the main incision and a paracentesis, were placed in a crisscross pattern (Figure 2A), and inferior pressure was applied to the iris. The micromanipulators were then repositioned parallel to each other to further stretch the iris (Figures 2B and 2C). With DisCoVisc inside the anterior chamber, I have incredible clarity of the surgical field, facilitating the maneuvers needed to stretch the iris.
Capsulorrhexis. After the pupil is enlarged, I inject more DisCoVisc into the anterior chamber to facilitate creation of a continuous curvilinear capsulorrhexis. In this case, the capsulorrhexis was 5.5 mm in diameter (Figure 3) to overlap the optic of the IOL to prevent posterior capsular opacification. Phacoemulsification, in this case, was made safer thanks to the synechiarrhexis technique.
Using the synechiarrhexis technique to tear out and remove membranous anterior synechiae is a safe alternative to other management techniques for synechiae in eyes with small pupils. When this controlled technique is applied, adequate pupil dilation can be achieved and the remainder of the procedure completed.
Thierry Amzallag, MD, practices at the Ophthalmic Institute of Somain, France. Dr. Amzallag states that he is a paid consultant to Alcon Laboratories, Inc., and Carl Zeiss Meditec. He may be reached at e-mail: Thierry.email@example.com.