Managing Femto Flap Complications

Complications associated with femtosecond laser flap creation in LASIK procedures may impede successful flap formation. However, implementing appropriate preoperative measures can minimise the risk of these complications, and a timely, effective response can help mitigate their impact if they arise, explained Namrata Sharma MD.

She noted that such flap complications can result from factors such as opaque bubble layer, anterior chamber air bubbles, vertical gas breakthrough, pseudosuction, suction loss or break, micro- or macro-adhesions, and flap holes. Proper docking helps reduce these risks, and Dr Sharma recommended preoperative counselling to promote patient cooperation during the procedure.

The incidence of the opaque bubble layer is between 5.0% and 7.6% and occurs less often with newer machines. It is caused by gas bubbles collecting in the cornea’s interlamellar spaces and can last several minutes after forming the lamellar bed, interfering with the surgeon’s view and impeding laser tracking devices. When air bubbles appear in the anterior chamber, the surgeon can wait for them to disappear before proceeding with the excimer laser ablation. However, Dr Sharma said that, in her experience, the bubbles do not compromise the procedure.

Vertical gas breakthrough occurs in 0.03% to 0.13% of cases—the result of a laser-induced optical breakdown in the interface, allowing gas to dissect along the plane of least resistance along the collagen lamellae. If there is an anterior corneal abnormality, gas migrates vertically, forming a visible black island that can be difficult to dissect. When vertical gas breakthrough occurs, the surgeon should stop the procedure by releasing the foot pedal. If the breakthrough occurs before the side cut, one option is to repeat the flap creation at a depth 50 microns greater than the original. Another option is to perform a surface ablation or LASIK at another time.

Dr Sharma stressed the importance of preventing suction loss, identifying pseudosuction and actual suction loss, and responding promptly. While modern machines have reduced the incidence, suction loss may lead to an incomplete flap, which typically occurs during the raster stage or side cut, primarily due to improper docking, entrapment of eyelashes, or oedematous conjunctiva.

In the event of suction loss, Dr Sharma advised completing the procedure immediately if the lamellar bed has been treated and there is no side cut. But if it occurs during the side cut, surgeons should avoid lifting the flap and instead create a new flap that is 0.5 mm smaller and 40 microns deeper. In rare cases, if the refractive error allows, a surface ablation may be performed.

Micro-adhesions primarily appear because gas bubbles do not always pass uniformly through the intended flap area. Minor adhesions can usually be carefully separated, while attempts to separate larger or more coalescent adhesions may increase the risk of flap tears or super holes. Proper LASIK flap hydration is important both during its creation and elevation.

Prof Sharma made her presentation at the 2025 ESCRS Annual Congress in Copenhagen.

Namrata Sharma FRCOphth, FRCSEd is Professor of Ophthalmology at the Cornea and Refractive Surgery Services, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. namrata.sharma@gmail.com