L-shaped scleral incision may be ideal for IOL explantation, insertion

Issue: August 2017

ByAmar Agarwal, MS, FRCS, FRCOphth

ByPriya Narang, MS

In intraocular surgery, the placement of an incision has a lot of significance pertaining to the amount of surgically induced astigmatism and the wound architecture. Taking into consideration the anatomical location, among the various types of incisions, scleral incisions have played a significant role in phacoemulsification and in small-incision cataract surgery. A “J-shaped” incision, an “inverse J-shaped” incision and an “L-shaped” incision have been described previously by surgeons in both peer- and non-peer-reviewed literature, and they have been employed for performing phacoemulsification and also for introducing an IOL.

The length and width of the incision, the relationship between the length and width of the incision, and the distance of the scleral incision from the limbus significantly affect postoperative astigmatism. A square incision wherein the length and width of the incision are equal is the most astigmatically stable wound, and an L-shaped incision has been considered to be superior to the conventional linear incision due to its astigmatically neutral wound architecture. The scar tissue tends to contract as much along its horizontal axis as its perpendicular axis. This principle probably helps to settle the issue of irregular scarring in a scleral incision, leading to an astigmatically neutral wound.

Hennekes and colleagues reported an L-shaped corneal tunnel incision for performing phacoemulsification. It has been thought that if the corneal tunnel is extended for IOL implantation, it is better to extend the wound perpendicularly in an L-shape rather than its linear extension. A comparative study of an L-shaped incision vs. a linear incision group revealed less induced astigmatism.

A similar comparative study has been done with an L-shaped scleral incision and a conventional 3.2-mm scleral tunnel incision in which a non-foldable IOL was inserted from the L-shaped incision and a foldable IOL was inserted from the 3.2-mm incision. Both groups reported a similar outcome, but the L-shaped incision allowed insertion of an IOL with a large diameter and facilitated the implantation of a less expensive PMMA IOL. We then used the L-shaped incision for IOL explantation and a subsequent secondary IOL fixation with glue-assisted intrascleral haptic fixation of an IOL. Beiko, Ohta and Brierly, who have also utilized this method for IOL explantation, conveyed the concept of utilization of an L-shaped incision to us.

Figure 1. A decentered IOL is seen along with an associated posterior capsular rupture. After conjunctival peritomy, two partial-thickness scleral flaps are made 180° opposite to each other. A 3-mm distance is selected on a vernier caliper (a). A 3-mm horizontal mark is made on the sclera (b). A 3-mm vertical mark is made such that an L-shaped incision will be framed (c). A further 3-mm marking is done to delineate the horizontal extension (intrascleral part) of the incision (d). An L-shaped incision is marked with a marker (e). An L-shaped incision is marked with a scleral dissector (f).

Figure 2. The marked incision is being dissected (a). The incision dissection is extended horizontally up to previous markings (b). Anterior chamber entry made with a keratome (c). The incision is enlarged with a keratome (d).

Figure 3. Iris hooks are placed in position to enlarge the small pupil. The IOL is grasped with end-opening forceps (a). The IOL is pulled from the L-shaped incision, and it comes out with ease (b). The IOL is explanted (c). A three-piece foldable IOL is introduced from the L-shaped scleral incision, and a glued IOL procedure is performed for secured IOL fixation (d).

Procedure

A patient presented with a decentered IOL and an associated posterior capsular rupture. After 180° axis marking, conjunctival peritomy was done, followed by framing of two partial-thickness scleral flaps along the ink mark (Figure 1a). A 3-mm mark was set on the vernier caliper, and the scleral incision was marked (Figures 1b to 1e). A crescent blade was used to make the tunnel along the L-shaped mark (Figure 1f). The tunnel was widened anteriorly and to the sides (intrascleral aspect), creating a nearly 6-mm wide tunnel. Infusion was introduced into the eye with the help of a trocar cannula, and a keratome was then used to enter the anterior chamber, creating a broad internal corneal lip (Figures 2a to 2d).

Because the pupil was small, iris hooks were placed to enhance the intraoperative view (Figure 3a). The decentered IOL was grasped and explanted (Figures 3b and 3c) followed by a thorough vitrectomy. A three-piece IOL was then introduced inside the eye (Figure 3d), and a glued IOL procedure ensued, followed by intrascleral haptic tuck and sealing of the flaps with fibrin glue. Postoperatively, the anterior chamber was stable with good wound structure and a properly placed IOL (Figures 4a and 4b).

To conclude, an L-shaped incision provides good chamber stability and ease of IOL explantation and insertion with the added advantage of good intrascleral extension to facilitate IOL manipulation. The incision seems to be superior to the conventional linear type in terms of wound stability, without the need to suture the tunnel at the end of the procedure, and also in terms of induced astigmatism.

Reference:
Hennekes RL, et al. J Cataract Refract Surg. 1999;doi:10.1016/S0886-3350(99)80054-6.

For more information:
Amar Agarwal, MS, FRCS, FRCOphth, is director of Dr. Agarwal’s Eye Hospital and Eye Research Centre. Agarwal is the author of several books published by SLACK Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; email: dragarwal@vsnl.com; website: www.dragarwal.com.
Priya Narang, MS, is the director of Narang Eye Care & Laser Centre, Ahmedabad, India. She can be reached at email: narangpriya19@gmail.com.

Disclosures: The authors report no relevant financial disclosures.