Handling KLEx Complications

As a treatment for myopia and myopic astigmatism, keratorefractive lenticule extraction (KLEx) offers several advantages compared with LASIK and PRK. But like all surgical procedures, it carries risks for intraoperative and postoperative complications. Awareness of these events, along with strategies for their prevention and management, is essential for achieving surgical success, according to Soosan Jacob MD.

Among intraoperative events, the most important are those related to lenticule creation, dissection, or extraction. Possible complications during lenticule creation include suction loss, opaque bubble layer (OBL) formation, black spot development, incisional bleeding, and subconjunctival haemorrhage.

Managing cases of suction loss depends on the timing of the loss—however, it is generally possible to proceed with KLEx unless the suction loss occurs after more than 10% of the lenticular cut has been completed.

“In such cases of suction loss, the procedure must be converted to femto-LASIK, and the treatment wizard will automatically convert to flap creation,” Dr Jacob said.

If suction is lost before 10% of the lenticule cut, surgeons can simply redock and restart the laser. If the loss happens while making the lenticule side cut, the procedure can be repeated, but the lenticule diameter should be decreased by 0.2 to 0.4 mm. Similarly, if the loss occurs during the cap side cut, the side cut can be repeated after reducing the cap diameter by 0.2 to 0.4 mm. In cases of suction loss during the cap cut, the surgeon can repeat the cut after recentring the procedure and clearing any central bubble.

Black spots are the result of inadequate laser energy delivery and typically occur due to interference from debris or secretions at the laser-cornea interface, which can lead to incomplete cuts with tissue bridges and difficult dissection.

“If the spots are small and in the periphery, they may not cause any problem. In more severe cases, it may be necessary to convert to surface ablation or LASIK. To avoid black spots, be certain the surface is completely clear before starting the procedure,” Dr Jacob advised.

The presence of an OBL, which forms from entrapment of cavitation bubbles, is a problem that interferes with lenticular dissection plane identification. Dissection in false planes can lead to severe irregular astigmatism, to which Dr Jacob suggested it is better to abort the procedure than make brave attempts to dissect in difficult scenarios.

Lenticule dissection complications

Complications relating to lenticule dissection include incisional epithelial loss, difficulty with dissection, cap tears, buttonholes, and lenticule adherence to the cap. Dr Jacob said incisional epithelial loss can occur due to excessive use of topical anaesthetic, a dry ocular surface, rough handling, or the presence of epithelial basement membrane dystrophy. She urged surgeons to be cautious in cases of incisional epithelial loss because it can lead to epithelial ingrowth or diffuse lamellar keratitis.

To enable smooth lenticule extraction and minimise the risk of cap tears, partial lenticule dissection, and torn lenticules, Dr Jacob emphasised the importance of dissecting the anterior plane first, followed by the posterior plane.

Surgeons can use what Dr Jacob calls the “white ring sign” as a valuable guide to differentiate between the anterior and posterior lenticular surfaces.¹ The white ring represents the circular white light reflected from the lenticular side cut, and it will lie below the dissector when the instrument is at the anterior lenticular plane and above the dissector when the instrument is at the level of the posterior plane, she explained.

To facilitate dissection in cases where there is a thin lenticule, Dr Jacob recommends the sequential segmental lenticular side cut dissection.¹ In this technique, the anterior lenticular plane is dissected first, followed by the central posterior lenticular plane. This leaves a thin, undissected area attached to the side cut, anchoring the lenticule and preventing it from moving or folding on itself during the remainder of the procedure. The sequential side cut dissection is performed by making short, sequential sweeps to separate the lenticule, leaving anchored points on either side for easy and complete lenticular dissection. Dr Jacob urges care when inserting instruments to avoid snagging the incision and creating tears.

Epithelial ingrowth risk

Dr Jacob said most of the possible postoperative complications associated with KLEx are like those seen after LASIK, except for epithelial implantation and epithelial ingrowth, which can lead to irregular astigmatism. Epithelial implantation occurs when epithelial cells are inadvertently pushed into the pocket intraoperatively, forming epithelial nests, whereas epithelial ingrowth refers to the postoperative migration of epithelial cells into the interface.

Although epithelial ingrowth is less common after SMILE compared to after LASIK, it can occur through the cap side cut, especially if there is a tear from excessive manipulation or trauma.

Dr Jacob said epithelial ingrowth after KLEx is best addressed by using CIRCLE software to convert the area of the cap into a flap, allowing for interface cleaning.

“Be sure to also scrape off the underside of the cap and then apply alcohol so no residual live cells remain,” she added.

Dr Jacob spoke at AAO 2025 in Orlando, US.

Soosan Jacob MS, FRCS, DNB is Director and Chief, Dr Agarwal’s Refractive and Cornea Foundation, Dr Agarwal’s Group of Eye Hospitals, Chenai, India. dr_soosanj@hotmail.com

Dr Jacob recommends viewing the following videos.

Learning SMILE—White Ring Sign for SMILE

Sequential segmental terminal Lenticular Side Cut dissection in SMILE

1. Jacob S, Agarwal A. J Refract Surg, 2018; 34(2): 140–141.