Potential treatments for patients presenting with small amounts of symptomatic refractive error many years following LASIK include: glasses, contact lenses, photorefractive keratectomy (PRK) or laser epithelial keratomileusis (LASEK), crystalline lens replacement, corneal or phakic implants, corneal arcuate incisions (in the case of astigmatism), LASIK performed by creating a new LASIK flap either within or below the existing flap, and LASIK performed by lifting the previously created flap (flap-lift LASIK).
LASIK offers the benefits of minimal pain and rapid return of vision. Creation of a new LASIK flap, either within or below the existing flap, is an option. However, there is a risk of the new flap intersecting with the original flap. When this complication occurs, a small sliver of stromal tissue will be created that is difficult to replace in the proper position if it becomes free with resultant irregular corneal curvature and loss of corrected distance visual acuity (CDVA).1
Multiple investigators have reported the results of flap-lift LASIK procedures.2–8 Complications appear to increase with the number of years between the initial LASIK and the secondary flap-lift LASIK.2,3 Epithelial ingrowth occurred more often for hyperopic enhancements than for myopic enhancements.9 The safety and efficacy of PRK and LASEK, the major excimer laser alternatives to LASIK re-treatment, are also analyzed in several reports.2,4–6,9 These studies all focus on enhancement procedures performed in the short- or medium-term time frame after the primary LASIK. To the best of our knowledge, there are no reports about the safety and efficacy of lifting a flap and performing LASIK many years (in this case, 10 or more years) after the flap was originally created. It is often difficult to obtain records on treatments performed many years previously, and patient recollections about the year procedures were performed are extremely unreliable. This study retrospectively reviews all results of flap-lift LASIK treatments in a group of patients in whom complete records about the initial and final treatments are available.
Patients and Methods
All patient records from our clinical practice in which flap-lift LASIK was performed were reviewed. Patients were included in this study only if (1) clinical records for the original LASIK and flap-lift LASIK were available, (2) flap-lift LASIK was performed at least 10 years after the primary LASIK, and (3) follow-up examination with refraction was available from at least 45 days after the most recent treatment.
Candidates for flap-lift LASIK were selected based on the following criteria: a lack of apparent abnormalities in the flap, clear media without any evidence of an incipient cataract, excellent eyelid margin health and function, adequate tear quality and quantity, adequate calculated stromal bed thickness, and absence of keratectasia by topography and tomography. Alternative treatment options including glasses, contact lenses, clear lens replacement, and PRK were also thoroughly discussed with the patients.
Briefly, the flap-lift LASIK procedure was performed by identifying and marking the flap edge at the slit-lamp and 3- and 9-o'clock alignment marks were placed on the conjunctiva if astigmatism was greater than −0.50 diopters (D). Using the operating microscope of the excimer laser, alignment marks were placed across the flap edge onto the peripheral cornea. The entire flap edge was then loosened from the bed using a Sinskey-style hook. The body of the flap was next loosened and lifted with a thin spatula (Slade LASIK Retreatment Spatula; ASICO, Westmont, IL) by making multiple passes under the flap. Care was taken to avoid loosening epithelium from the surface of the flap or adjacent cornea, and the sweeping of loose epithelium under the flap. If peripheral epithelial ingrowth was present, it was removed by gentle scraping. The excimer laser (Allegretto Wave Eye-Q) was previously programmed using the same nomogram as a virgin treatment. After the application of the excimer laser energy, the corneal bed and underside of the flap were carefully wiped with a wet sponge to remove loose epithelium and the flap was replaced. The hinge was lightly stroked with a moist sponge to push fluid away from the hinge and toward the flap center, ensuring proper alignment. The flap center was not stroked with the sponge to avoid creating microfolds in the central corneal flap. No contact lens was used postoperatively. Postoperatively, dilute anesthetic drops were provided for the first night to be used on an as-needed basis, antibiotic drops were prescribed for 1 week, and steroid drops were used for 2 to 4 weeks on a tapering basis.
Nineteen eyes were myopic prior to the first LASIK treatment, with a median spherical equivalent of −3.37 D (range: −1.50 to −8.25 D). Four eyes were originally hyperopic, with a median spherical equivalent of +2.63 D (range: +1.88 to +5.00 D). The median original cylinder in all patients was −0.75 D (range: 0.00 to −3.50 D). All eyes had CDVA of at least 20/20 after the initial LASIK treatments.
Re-treatments were performed between 2013 and 2017 using the Alcon WaveLight Allegretto laser (Alcon Laboratories, Inc.). Two eyes in the cohort underwent cataract removal approximately 13 and 14 years after the initial LASIK treatments and then had flap-lift LASIK as an enhancement after cataract extraction. The remainder of the patients had no intervening ophthalmic surgeries, except the 4 eyes that underwent initial early LASIK enhancements.
Of the 19 eyes that were originally myopic, 10 eyes were re-treated 10 or more years later with a myopic spherical equivalent and 9 were re-treated with a hyperopic spherical equivalent. Three of the eyes over the 10 or more year period following the primary surgery developed and were subsequently treated for astigmatism greater than 1.00 D (maximum: 1.75 D). Three of 4 originally hyperopic eyes regressed from the primary treatment and therefore sought hyperopic re-treatment 10 or more years later. One hyperopic eye underwent cataract removal elsewhere and the refraction before cataract was not known.
A total of 23 eyes of 20 patients were identified that matched the inclusion criteria (Table 1). Ten were men and 13 were women. The median age at original LASIK treatment was 44 years (range: 29 to 64 years). The median age at secondary flap-lift LASIK treatment was 58 years (range: 41 to 79 years). The median time between primary LASIK and final flap-lift LASIK was 13.9 years (range: 10 to 18.7 years).
Patient Demographic and Refractive Data
Of the original LASIK treatments, 22 were performed with a mechanical microkeratome (20 Hansatome [Bausch & Lomb, Bridgewater, NJ], 1 ACS [Bausch & Lomb], 1 Moria [Moria SA, Antony, France]) and 1 was treated with a femtosecond laser (IntraLase; Johnson & Johnson Vision, Santa Ana, CA). The original treatments were performed between 1998 and 2004. Twelve original treatments were performed with the VisX laser (Johnson & Johnson Vision) and 11 treatments with the LadarVision laser (Alcon Laboratories, Inc., Fort Worth, TX). No operative or perioperative complications occurred in the 23 original LASIK treatments. However, 4 eyes from 4 patients underwent enhancement flap-lift LASIK procedures within the first 18 months following the primary LASIK treatment.
After all treatments (including additional procedures), 14 of 20 eyes (70%) with a goal of plano achieved UDVA of 20/20; 6 eyes (30%) achieved UDVA of 20/25 (2 of these eyes had preoperative CDVA of 20/25). For the eyes with a goal of plano, 16 of 20 eyes (80%) achieved UDVA equal to the preoperative CDVA. The 3 eyes with a goal of myopia for monovision achieved the desired functional result (Figure 1).
Standard Graphs for Corneal Refractive Surgery showing the results of flap-lift LASIK 10 or more years after primary LASIK.
Prior to the secondary flap-lift LASIK treatments, 21 of 23 eyes had a CDVA of 20/20 or better and 2 eyes had a CDVA of 20/25. A total of 22 of 23 eyes (96%) retained the same CDVA after re-treatment that was present before re-treatment; 1 of 23 eyes (4%) experienced a loss of one line of CDVA from 20/20 to 20/25.
Two eyes (from different patients) (9%) had clinically significant epithelial ingrowth that required flap-lift and removal of the ingrowth. Six eyes (26%) were noted to have epithelial ingrowth limited to the periphery, which was deemed not clinically significant and therefore was not treated. For 1 patient, a single epithelial removal treatment was sufficient. However, for 1 patient a total of three epithelial removal procedures were performed with a resulting loss of one line of CDVA. This eye required subsequent treatment with PRK to optimize UDVA.
The eyes with clinically significant epithelial in-growth did not differ from those of the overall study population in any discernible way. These eyes were treated 11 and 14 years after the primary LASIK. Both of these eyes had the flap originally created with the Hansatome and both originally had moderate myopia. These patients were 45 and 56 years old at the time of re-treatment. One of the 2 eyes that developed clinically significant epithelial ingrowth was treated with a hyperopic treatment as the secondary enhancement and 1 eye was treated with a myopic treatment.
One eye (4%) required an additional enhancement laser vision correction treatment following the secondary flap-lift treatment. This was the eye that required three epithelial ingrowth removal procedures before achieving control of the epithelial ingrowth, with resulting residual refractive error. The patient then underwent a PRK enhancement and obtained UDVA and CDVA of 20/25. This was also the eye that experienced a one-line loss of CDVA.
One eye (4%) experienced moderate dry eye symptoms that were still present at the 6-month postoperative visit but had resolved by the 9-month visit. The patient with these symptoms was by far the oldest patient in our cohort (79 years old).
There were no complications of the flap-lift LASIK re-treatments other than the 2 cases of clinically significant epithelial ingrowth and the 1 case of moderate but temporary dry eye.
This study demonstrates that lifting a flap to perform secondary LASIK 10 or more years after the primary LASIK procedure is an effective treatment for refractive error. Additional excimer laser enhancement was needed only in a single case, one that was complicated by epithelial ingrowth. The treatment was effective for patients of a wide age range (41 to 79 years old). Two of the eyes were treated following cataract extraction.
Secondary flap-lift LASIK treatments are easy to perform and typically cause little postoperative discomfort. As opposed to PRK healing, visual acuity after secondary flap-lift LASIK is rapidly restored. Many surgeons worry that the flaps might be difficult to lift after this period of time, but in these 23 cases there were no situations in which it was particularly difficult to lift the flap and perform the treatment. It can be difficult to identify the flap edge, but careful inspection, including indirect lighting, will almost always allow for identification of the flap edge.
There were 3 eyes with complications: 2 eyes (9%) experienced clinically significant epithelial ingrowth and 1 eye (4%) experienced moderate but temporary dryness for at least 6 months. The patient with the moderate dryness had her symptoms resolve by 9 months. This was in a 79-year-old patient, one of the oldest patients in whom we have ever performed secondary flap-lift LASIK. There were no infections and no problems with flap realignment or flap slippage. Keratectasia is unlikely due to the typically low level of refractive error, the respect for a limit on the proposed corneal bed thickness, and the older age of this population; in fact, no cases of keratectasia were noted.
Flap-lift LASIK is one of several options available. Some physicians might consider performing LASIK within or around and under the previous LASIK flap. Caution is recommended regarding this option due to the extreme negative refractive consequences of creating a free wedge of intersecting corneal tissue.10 For the patient with mild cataract and in older patients, crystalline lens replacement should be considered. PRK is typically also an option.11 LASIK, PRK, and crystalline lens replacement are highly effective in obtaining predictable visual results. The recovery from flap-lift LASIK, in the absence of complications, is clearly much easier and faster than for PRK. LASIK, whether primary or secondary flap-lift LASIK, is not intraocular and thus has fewer serious potential complications than crystalline lens replacement.
Previous analysis by Caster et al.3 revealed a rate of 1% of clinically significant epithelial ingrowth in flap-lift secondary LASIK performed less than 3 years after primary LASIK. This rate jumped to 8% when the re-treatment was 3 to 10 years after primary LASIK, and remained more or less constant during this time frame (regression line slope: 0.2). However, there was a large amount of scatter in the study with small numbers in the outlying years and thus the regression line was not conclusive (P = .40). Nevertheless, extrapolation from that data set is consistent with the finding in this study of a 9% rate of clinically significant epithelial ingrowth when there were 10 to 18.7 years between LASIK and flap-lift LASIK.
The major risk of performing flap-lift LASIK is epithelial ingrowth. We do not understand the pathophysiology of epithelial ingrowth. Seeding of the interface with epithelial cells during flap separation and lifting could be a factor. With careful technique, including minimal but effective irrigation, this should be avoidable. Most cases probably result from the flap edge not sealing properly, allowing epithelial cells to migrate under the flap edge. Use of a tissue sealant at the flap edge has been reported in cases of flap-lift for epithelial ingrowth removal, but could also be used in cases of flap-lift LASIK re-treatment.11 Does edema created by the surgery play a role? Are inflammatory conditions and dryness predisposing factors? If so, cases with blepharitis, Meibomian gland dysfunction, or aqueous tear deficiency should be treated with caution. Pretreatment of these conditions before flap-lift LASIK is strongly advised, and adequate postoperative inflammation control is probably important. Not lifting irregular flaps or smaller flaps (eg, from previous ACS microkeratomes) when combined with today's larger excimer treatment profiles is probably wise.
One of the two cases of epithelial ingrowth in this series had a healing pattern that was typical in the experience of the author and one had a course that was atypical. In the more typical case, the epithelial in-growth required only one procedure to treat with no recurrence and no loss of UDVA or CDVA. However, the other case of epithelial ingrowth in this cohort had a difficult treatment course requiring multiple procedures with a loss of one line of UDVA and CDVA. If the complication of epithelial ingrowth can be treated with one rapid, painless procedure, then an occurrence rate of approximately 9% may be acceptable. However, if the epithelial ingrowth requires multiple procedures and results in a loss of UDVA or CDVA, then techniques other than flap-lift LASIK might be preferable.
- Rubenfeld RS, Hardten DR, Donnenfeld ED, et al. To lift or recut: changing trends in LASIK enhancement. J Cataract Refract Surg. 2003;29:2306–2317. doi:10.1016/j.jcrs.2003.08.013 [CrossRef]
- Ortega-Usobiaga J, Llovet-Osuna F, Katz T, et al. Comparison of 5468 retreatments after laser in situ keratomileusis by lifting the flap or performing photorefractive keratectomy on the flap. Arch Soc Esp Oftalmol. 2017;93:60–68. doi:10.1016/j.oftal.2017.05.007 [CrossRef]
- Caster AI, Friess DW, Schwendeman FJ. Incidence of epithelial ingrowth in primary and retreatment laser in situ keratomileusis. J Cataract Refract Surg. 2010;36:97–101. doi:10.1016/j.jcrs.2009.07.039 [CrossRef]
- Schallhorn SC, Venter JA, Hannan SJ, Hettigner KA, Teenan D. Flap lift and photorefractive keratectomy enhancements after primary laser in situ keratomileusis using a wavefront-guided ablation profile: refractive and visual outcomes. J Cataract Refract Surg. 2015;41:2501–2512. doi:10.1016/j.jcrs.2015.05.031 [CrossRef]
- Beerthuizen JJ, Siebelt E. Surface ablation after laser in situ keratomileusis: retreatment on the flap. J Cataract Refract Surg. 2007;33:1376–1380. doi:10.1016/j.jcrs.2007.04.024 [CrossRef]
- Cagil N, Aydin B, Ozturk S, Hasiripi H. Effectiveness of laser-assisted subepithelial keratectomy to treat residual refractive errors after laser in situ keratomileusis. J Cataract Refract Surg. 2007;33:642–647. doi:10.1016/j.jcrs.2007.01.012 [CrossRef]
- Mohamed TA, Hoffman RS, Fine IH, Packer M. Post-laser assisted in situ keratomileusis epithelial ingrowth and its relation to pretreatment refractive error. Cornea. 2011;30:550–552. doi:10.1097/ICO.0b013e3182000ac3 [CrossRef]
- 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;28:488–492. doi:10.3928/1081597X-20120604-01 [CrossRef]
- Lee BS, Gupta PK, Davis EA, Hardten DR. Outcomes of photorefractive keratectomy enhancement after LASIK. J Refract Surg. 2014;30:549–556. doi:10.3928/1081597X-20140711-08 [CrossRef]
- Chuck RS, Jacobs DS, Lee JK, et al. Refractive errors and refractive surgery preferred practice pattern. Ophthalmology. 2018;125:P1–P104. doi:10.1016/j.ophtha.2017.10.003 [CrossRef]
- Ramsook SS, Hersh PS. Use of hydrogel sealant in epithelial ingrowth removal after laser in situ keratomileusis. J Cataract Refract Surg. 2015;41:2768–2771. doi:10.1016/j.jcrs.2015.11.024 [CrossRef]
Patient Demographic and Refractive Data
|Eye No.||Original Refraction||Age Original Lasik (y)||Age at Flap-Lift LASIK (y)||Years Between Surgeries||Pre Flap-Lift Refraction||Pre Flap-Lift CDVA||Flap-Lift Goal||Post Flap-Lift Refraction||Post Flap-Lift UDVA||Post Flap-Lift CDVA|
|1||−1.00 −1.00 × 100°||35||46||10.0||−0.25 −0.50 × 50°||20/20||0.00||+0.5 −0.50 × 108°||20/20||20/20|
|2||−2.00 −0.50 × 55°||62||72||10.0||+2.00 −0.75 × 50°||20/20||0.00||plano −0.50 × 113°||20/20||20/20|
|3||−4.00 −0.50 × 32°||39||50||10.3||−0.25 −0.75 × 35°||20/20||0.00||+0.25 −0.75 × 50°||20/25||20/20|
|4||−2.87 −2.00 × 99°||44||54||10.6||+0.75 sph||20/20||0.00||+0.25 −0.25 × 110°||20/25||20/25|
|5||−2.12 −2.25 × 62°||44||54||11.0||+0.50 −0.75 × 55°||20/20||0.00||+1.00 −0.25 × 33°||20/20||20/20|
|6||+2.5 −0.25 × 65°||53||64||11.0||+0.50 −1.00 × 51°||20/20||−2.00||−1.75 −1.75 × 180°||20/200||20/20|
|7||+3.25 −0.75 × 80°||53||64||11.1||+2.25 −0.75 × 127°||20/20||0.00||+0.25 −0.50 × 150°||20/20||20/20|
|8||−8.00 −0.50 × 95°||29||41||11.1||−0.50 −0.50 × 12°||20/20||0.00||+0.25 −0.75 × 40°||20/20||20/20|
|9||−4.50 −3.50 × 163°||47||60||11.6||−0.50 −0.25 × 130°||20/20||0.00||+0.25 −0.50 × 30°||20/20||20/20|
|10||+5.75 −1.50 × 180°||36||49||13.3||−1.00 −1.00 × 135°||20/25||0.00||+0.25 −0.25 × 3°||20/25||20/25|
|11||−3.37 sph||34||48||13.5||−0.50 −0.25 × 105°||20/20||0.00||+0.50 −0.50 × 180°||20/20||20/20|
|12||−4.1 −0.25 × 75°||32||46||13.8||−2.50 −0.25 × 020°||20/20||0.00||+0.25 −0.50 × 38°||20/20||20/20|
|13||−2.50 sph||44||58||13.9||−0.25 −0.25 × 125°||20/20||−1.75||−2.25 −1.00 × 101°||20/200||20/20|
|14||−1.5 −0.25 × 127°||44||58||14.0||+0.75 sph||20/20||0.00||+0.75 −0.25 × 66°||20/20||20/20|
|15||−4.37 −0.75 × 4°||31||45||14.0||−0.75 −0.75 × 20°||20/20||0.00||+0.25 −0.25 × 115°||20/20||20/20|
|16||+2.00 −0.25 × 3°||64||79||14.0||+1.75 sph||20/20||0.00||plano −0.75 × 76°||20/25||20/20|
|17||−4.75 −0.75 × 8°||50||66||15.2||−1.00 −0.50 × 170°||20/20||0.00||+0.50 −0.50 × 74°||20/25||20/20|
|18||−1.87 sph||48||64||15.8||+1.75 −0.75 × 50°||20/20||0.00||+0.25 sph||20/20||20/20|
|19||−1.37 −0.37 × 60°||48||64||16.1||+1.25 −0.75 × 110°||20/20||0.00||+0.75 −0.25 × 25°||20/20||20/20|
|20||−4.25 −1.25 × 176°||35||52||16.1||−0.25 −0.50 × 58°||20/20||0.00||+0.50 sph||20/20||20/20|
|21||−3.00 −1.00 × 60°||30||48||16.8||−0.75 −1.25 × 63°||20/20||0.00||plano −0.25 × 84°||20/20||20/20|
|22||−2.50 −1.25 × 150°||40||59||17.2||+1.75 −1.75 × 122°||20/25||0.00||+0.25 −1.00 × 114°||20/25||20/25|
|23||−2.00 −2.00 × 72°||40||59||18.7||+1.00 −1.25 × 79°||20/20||−1.75||−1.50 −0.75 × 94°||20/200||20/20|