When the anatomical integrity of a LASIK flap is compromised, its amputation may be necessary to preserve vision. As there is a paucity of evidence and no clear consensus on LASIK flap amputation, here we discuss the clinical indications for this procedure and the technique that we found optimized outcomes, according to a recent meta-analysis by our group.¹ 

Clinical Indications
In cases of flap-related complications in which conservative treatment does not suffice, amputation of the LASIK flap may be required to preserve visual function and, sometimes, the structural integrity of the globe.^2,3,4

In our meta-analysis of 72 eyes from 27 studies, microbial keratitis was the most common cause for flap amputation, with 80.5% of eyes requiring flap amputation as a result.¹ While the offending microorganisms varied, with representation from gram-negative, gram-positive, and fungal species, insufficient penetration of antimicrobials into the interface area was a common reason for flap amputation. Additionally, the literature showed epithelial ingrowth (9.7%) is commonly reported as an indication for flap amputation.

Less commonly, flap amputation may be required for diffuse lamellar keratitis (DLK) (2.8%), recalcitrant irregular astigmatism (2.8%), or, in instances of corneal pathologies, such as granular dystrophy (2.8%), within the LASIK flap.¹

Additionally, the literature revealed one case of LASIK flap amputation following a flap melt from prolonged use of nonsteroidal anti-inflammatory drops.¹

Technique
In our meta-analysis, patients achieved a mean uncorrected visual acuity (UCVA) of 20/60 and a mean best-corrected visual acuity (BCVA) of 20/40, with a mean refractive spherical equivalent of -0.31 D after flap amputation.¹ At the Bascom Palmer Eye Institute, we like to use the following protocol to manage these cases:

1. Providing preop patient education. In all cases, patients undergoing flap amputation were and are counseled that their visual prognosis remains guarded, and that the procedure is being pursued to preserve the anatomical and functional integrity of the eye, not provide spectacle independence. Some patients may require rigid gas permeable or scleral/semi-scleral contact lenses for their best vision. Others may pursue additional photorefractive keratectomy for residual refractive error. (In these patients, it is important to ensure that the residual stromal depth exceeds 325 µm to ensure biomechanical stability of the cornea.)

2. Careful identification of the flap architecture. In many cases of interface complications, the edges of the flap and the hinge may be clearly visible because of the underlying pathology. If the edges are not clearly discernible, we use the bend of a Sinskey hook to apply gentle pressure to the peripheral cornea, creating an indent that brings the flap edge into view.

3. Gently lifting the flap tissue. Once the flap edge has been identified, the Sinskey hook can be used to gently lift the 270° of unhinged, free-flap tissue, taking care not to create an epithelial defect.

4. Freeing the central flap tissue. Next, a blunt spatula is used to free the central flap tissue from the underlying stromal bed and break any remaining adhesions.

5. Cutting the flap at its hinge. Finally, curved deep anterior lamellar keratoplasty scissors can be used to cut the flap at its hinge, thereby freeing it from the cornea.

6. Sending the amputated flap for pathological +/- microbiological analysis. Depending on the reason for flap amputation, additional treatment to the underlying stroma can be pursued. If the reason is microbial keratitis, for example, we culture the underlying stroma, irrigate it with antibiotic solution, place a bandage contact lens, and continue the patient on topical therapy.

If the reason is epithelial ingrowth, as another example, we scrape any remaining nests of epithelial cells. In some cases, limited phototherapeutic keratectomy (PTK) (with or without application of mitomycin C) to the residual stromal bed may be used to address haze or stromal surface irregularities.

Once the underlying etiology has been managed, the cornea may continue to heal for a period of 6 months or more.

7. Scheduling close follow-ups. It is our practice to have all patients who undergo flap amputation followed with serial refractions (both automated and manifest), tomography, anterior-segment OCT, and, if needed, specular microscopy on a monthly basis. This is because stromal irregularities are often masked by epithelial remodeling in the short term, and the final visual result may not be achieved for several months or years. (See “Case Report: LASIK Flap Amputation in Action.”)

Don’t Fear Flap Amputation
Although the epithelial-stromal flap constructed during LASIK plays an important role in postoperative wound healing, patient comfort, and final visual outcome, as with any refractive surgery, complications can arise that, in some cases, necessitate its amputation. As our case and meta-analysis demonstrate, if the underlying etiology is managed effectively, in most cases, patients will retain functional UCVA and good BCVA. CP

Case Report: LASIK Flap Amputation in Action

A 46-year-old female patient was referred to the Bascom Palmer Eye Institute for management of recurrent epithelial ingrowth with concomitant irregularity of her LASIK flap OD.

She underwent myopic microkeratome-flap LASIK in 2005 and a flap-lift enhancement in 2020. The patient developed epithelial ingrowth following her enhancement and underwent a flap lift and debridement twice prior to referral, which was complicated by DLK with flap melt and macrostriae in the visual axis.

The patient’s UCVA was 20/200, and her BCVA (with spectacles) was 20/50. On examination, we noted recurrent epithelial ingrowth, grossly irregular astigmatism, central corneal haze, and flap macrostriae (Figure 1).

We reviewed options at length with our patient, including repeat flap lift, debridement, and flap suturing or flap amputation. We agreed that flap lift and debridement alone would leave considerable visual impairment from central corneal haze and irregular astigmatism, so we elected to proceed with flap amputation in concert with PTK to the residual stromal bed.

We followed the protocol for flap amputation described in the main text, proceeding with a 20 μm ablation afterwards to regularize the underlying stroma, and application of mitomycin C for 12 seconds (Figure 2). 

‘Re-epithelialization of the stromal bed was complete within 7 days and by one month. The patient’s cornea was clear on slit lamp exam, and her subjective visual distortions had improved.

Her BCVA at this point remained limited to 20/60, largely secondary to dryness of the ocular surface and persistent irregular astigmatism.

Over the ensuing months, we continued to treat this patient’s ocular surface with ample lubrication that allowed for epithelial remodeling.

At her 6-month visit, her UCVA was 20/100, and her BCVA had improved to 20/25 with spectacles and 20/20 with a scleral contact lens. CP

Siddharth Nath, MD, PhD is a senior ophthalmology resident at McGill University in Montreal, Canada and an Honorary Research Fellow at Moorfields Eye Hospital in London, UK. He has a strong clinical and research interest in corneal disease, and his work has been published in leading medical journals. Dr. Nath has no relevant disclosures.

RAHUL TONK, MD, MBA is an assistant professor of clinical ophthalmology and a cornea, cataract, and refractive surgeon at the Bascom Palmer Eye Institute, in Miami, Florida. He also serves as co-director of the Cornea Clinical Fellowship. Dr. Tonk has no relevant disclosures.

References

1. Nath S, Mulpuri LK, Yoo SH, Tonk RS. Epidemiology of LASIK flap amputation: a systematic review and meta-analysis. Paper presented at: Annual meeting of the American Academy of Ophthalmology 2023; San Francisco, CA; November 3-6, 2023.

2. Karp CL, Tuli SS, Yoo SH, et al. Infectious keratitis after LASIK. Ophthalmology. 2003;110(3):503-510. doi: 10.1016/S0161-6420(02)01760-8.

3. Henry CR, Canto AP, Galor A, Vaddavalli PK, Culbertson WW, Yoo SH. Epithelial ingrowth after LASIK: clinical characteristics, risk factors, and visual outcomes in patients requiring flap lift. J Refract Surg. 2012;28(7):488-492. doi: 10.3928/1081597X-20120604-01.

4. Chhadva P, Cabot F, Galor A, Karp CL, Yoo SH. Long-term outcomes of flap amputation after LASIK. J Refract Surg. 2016;32(2):136-137. doi: 10.3928/1081597X-20151229-01