Journal of Refractive Surgery

Original Article 

Management and Outcomes of Suction Loss During LASIK Flap Creation With a Femtosecond Laser

Minoru Tomita, MD, PhD; Miyuki Watabe, PhD; Tadayuki Nakamura, MD; Nobuo Nakamura, MD, PhD; Tadahiko Tsuru, MD, PhD; George O. Waring IV, MD

Abstract

PURPOSE:

To evaluate risk factors, management, and outcomes in patients who experienced suction loss during LASIK flap creation with a femtosecond laser (Intra-Lase FS 60, Abbott Medical Optics Inc).

METHODS:

Pre- and postoperative visual outcomes and refractions for 71 eyes of 70 patients after suction loss during flap creation with the IntraLase FS60 femtosecond laser were analyzed and studied.

RESULTS:

In patients requiring a second or third lamellar flap cut immediately after suction loss, 97.2% of eyes achieved uncorrected distance visual acuity of 0.00 logMAR (20/20) or better and 100% of eyes achieved corrected distance visual acuity of 0.00 logMAR (20/20) or better at most recent follow-up.

CONCLUSIONS:

Our study suggests that excellent visual outcomes can be achieved if an immediate lamellar recut is performed after suction loss with a femtosecond laser.

Abstract

PURPOSE:

To evaluate risk factors, management, and outcomes in patients who experienced suction loss during LASIK flap creation with a femtosecond laser (Intra-Lase FS 60, Abbott Medical Optics Inc).

METHODS:

Pre- and postoperative visual outcomes and refractions for 71 eyes of 70 patients after suction loss during flap creation with the IntraLase FS60 femtosecond laser were analyzed and studied.

RESULTS:

In patients requiring a second or third lamellar flap cut immediately after suction loss, 97.2% of eyes achieved uncorrected distance visual acuity of 0.00 logMAR (20/20) or better and 100% of eyes achieved corrected distance visual acuity of 0.00 logMAR (20/20) or better at most recent follow-up.

CONCLUSIONS:

Our study suggests that excellent visual outcomes can be achieved if an immediate lamellar recut is performed after suction loss with a femtosecond laser.

From Shinagawa LASIK Center, Chiyodaku, Tokyo, Japan (Tomita, Watabe, T. Nakamura, N. Nakamura, Tsuru); ReVision Advanced Laser Eye Center, Columbus, Ohio (Waring); and St Joseph’s Translational Research Center, Atlanta, Georgia (Waring).

The authors have no financial or proprietary interests in the materials presented herein.

AUTHOR CONTRIBUTIONS

Study concept and design (M.T.); data collection (M.W.); analysis and interpretation of data (M.T., M.W., T.N., N.N., T.T., G.O.W.); drafting of the manuscript (M.W.); critical revision of the manuscript (M.T., T.N., N.N., T.T., G.O.W.); statistical expertise (M.W.); administrative, technical, or material support (M.T., T.N., N.N., T.T.)

Correspondence: Minoru Tomita, MD, PhD, Shinagawa LASIK Center, Yurakucho ITOCiA 14F, 2-7-1 Yurakucho, Chiyodaku, Tokyo, 100-0006, Japan. Tel: 81 3 5221 2207; Fax: 81 3 5221 8138; E-mail: tomita@shinagawa.com

Received: December 05, 2010
Accepted: October 11, 2011
Posted Online: December 02, 2011

Laser in situ keratomileusis (LASIK) is a useful and widely used procedure for the correction of refractive errors.1 Laser in situ keratomileusis technology has undergone many advances over the years, and the procedure is well documented. On rare occasions, surgeons may experience complications when creating flaps with a mechanical microkeratome such as incomplete flaps and flap buttonholes.2,3 When these complications arise, most surgeons recommend postponing the procedure for 2 weeks to a few months.4,5

Previously reported causes of suction loss include significantly flat keratometric power (K-readings <42.00 diopters [D]), small palpebral apertures, deep-set eyes, excessive eyelid squeezing by the patient, inability to maintain fixation, and/or not following instructions.6,7 In this study, suction loss during the creation of the lamellar flap with a femtosecond laser was evaluated. This study represents the largest reported series of femtosecond laser–related suction loss and subsequent management of this complication.

Patients and Methods

Patient Population

Seventy-one eyes of 70 patients (53 men [54 (76.1%) eyes], 17 women [17 (23.9%) eyes]) who experienced suction loss during LASIK with a femtosecond laser between September 2006 and August 2008 at Shinagawa LASIK Center, Tokyo, Japan, were analyzed. A total of 232 000 procedures were performed during the study period.

Surgical Technique

For the LASIK procedure, the IntraLase FS 60 femtosecond laser (Abbott Medical Optics Inc, Santa Ana, California) was used for flap creation and the Allegretto Wave Eye-Q 400-Hz excimer laser (WaveLight/Alcon Laboratories Inc, Ft Worth, Texas) was used for the refractive correction. The flap parameters were intended thickness of 100 μm, bed energy of 1.0 μJ, side-cut energy of 1.0 μJ, and spot and line separation of 8 μm.

In all cases, the right eye was operated first. Eye speculums were not used in any cases in this study. Before placement, the suction ring was inspected for defects by the surgeon. During flap creation, the fellow eye was closed with surgical tape to aid in patient fixation. After the suction ring was applied by the surgeon, the patient was asked to confirm dimming of his vision.

Anatomic variations such as small interpalpebral fissures or tight orbits predisposed patients to difficulty in suction ring placement. If suction loss occurred during the raster stage, all flaps were recreated at the same depth as the first attempt with the “pocket off” function immediately after the initial attempt. The same flap diameter as the initial cut was used. If suction loss occurred during the side-cut stage, the flap diameter was reduced by 0.2 mm and the next cut was created using the side-cut only function. Typically, flap lift is initiated by separating the lamellar flap from the stromal bed with a LASIK cannula near the hinge. In the case of suction loss, the flap was lifted from the inferior position, opposite of the hinge, with a LASIK cannula. Although the same patient interface was used for the second/third attempt, the applanation pressure was not always the same as the first attempt. In this case, the flap may be created slightly shallower/deeper than intended. Because the raster pattern begins superiorly and ends inferiorly, it is believed that an inferior lift after a recut is less likely to result in an incomplete flap. By lifting from the most inferior side, the chance of engaging a false passage leading to flap irregularity was decreased. After flap creation, normal excimer laser ablation was completed uneventfully in all cases.

Analysis

Preoperative and 1-day, 1-week, and 3-month postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction spherical equivalent (MRSE) were measured and analyzed. Data were statistically analyzed using paired t test and chi-square test where applicable. A P value <.05 was considered statistically significant.

Results

Postoperative examinations at 1 day, 1 week, and 3 months after LASIK were attended by 70 (100%) patients (71 eyes), 54 (77%) patients (55 eyes), and 19 (27%) patients (19 eyes), respectively. The Figure illustrates suction loss during LASIK flap creation with a femtosecond laser.

Suction loss during flap creation using the IntraLase FS 60 femtosecond laser. A) First ablation started. B) First suction loss. C) Second ablation started. The arrow points to the cut made by the femtosecond laser when the first suction loss occurred. D) Second suction loss. Arrow a shows where the suction loss occurred, and arrow b demonstrates the cut line created after the second suction loss. E) Flap creation is completed with a side cut. F) Smooth stromal surface. A flap was lifted for excimer laser ablation.

Figure. Suction loss during flap creation using the IntraLase FS 60 femtosecond laser. A) First ablation started. B) First suction loss. C) Second ablation started. The arrow points to the cut made by the femtosecond laser when the first suction loss occurred. D) Second suction loss. Arrow a shows where the suction loss occurred, and arrow b demonstrates the cut line created after the second suction loss. E) Flap creation is completed with a side cut. F) Smooth stromal surface. A flap was lifted for excimer laser ablation.

The incidence of suction loss in this study was 0.03% (71 of 232 000 eyes). Mean patient age was 33.0±8.86 years (range: 18 to 57 years). The ratio of men (76.1%) who had suction loss was statistically higher than the ratio of women (chi-square test, P≤.0001) when compared to the sex ratio of patients who underwent LASIK in our clinic during the same period (male:female, 49.4:50.6).

The rate of suction loss occurring in the right eye (the first surgical eye) was 60.6% (43 eyes) and 39.4% (28 eyes) in the left eye (chi-square test, P=.0750). Pre- and postoperative UDVA, CDVA, and MRSE results are shown in Table 1. The percentages of eyes achieving UDVA of 0.00 logMAR (20/20) or better 1 day, 1 week, and 3 months postoperatively were 100% (n=71), 94.5% (n=52), and 100% (n=19), respectively. Uncorrected distance visual acuity was significantly improved at 3 months after LASIK compared to preoperative (paired t test, P<.0001). All eyes achieved CDVA of 0.00 logMAR (20/20) or better at 1 day, 1 week, and 3 months after LASIK. No eyes lost CDVA relative to preoperative measurements at 3 months after LASIK (paired t test, P=.9610). Safety and efficacy indices were 1.00 and 0.94, respectively. At 1 day, 1 week, and 3 months after LASIK, 80.3%, 85.7%, and 100% of eyes, respectively, were within ±0.50 D of emmetropia and 95.8%, 94.5%, and 100% of eyes, respectively, were within ±1.00 D of emmetropia. Manifest refraction spherical equivalent was significantly improved at 3 months after LASIK compared to preoperative (paired t test, P<.0001). At 3 months after LASIK, manifest refraction cylinder was within ±0.50 D for 95.6% and within ±1.00 D for 100% of 19 eyes.

Pre- and Postoperative Visual and Refractive Outcomes in Patients Who Experienced Suction Loss During LASIK Performed With a Femtosecond Laser

Table 1: Pre- and Postoperative Visual and Refractive Outcomes in Patients Who Experienced Suction Loss During LASIK Performed With a Femtosecond Laser

Characteristics

In our clinic, 71 cases of suction loss involving 20 doctors were confirmed over 24 months. Although slight variations in technique may exist, all surgeons included in this study have operated on more than 3000 eyes each. The suction losses occurred at different stages of flap creation (Table 2). In 5 eyes, stromal step-like irregularities were observed on the stromal bed outside of the entrance pupil prior to excimer ablation. These stromal irregularities were reduced but still slightly visible after excimer laser ablation.

Visual and Refractive Outcomes According to Incidence of Suction Loss During LASIK Performed With a Femtosecond Laser

Table 2: Visual and Refractive Outcomes According to Incidence of Suction Loss During LASIK Performed With a Femtosecond Laser

Discussion

In the standard LASIK procedure, creation of a lamellar flap with a microkeratome or a femtosecond laser allows correction of myopia, hyperopia, and astigmatism by ablation of the stromal bed with an excimer laser.8,9 The safety and efficacy of creating a flap with a microkeratome or femtosecond laser has been well documented.10,11 Complications such as flap buttonholes and incomplete flaps caused by suction loss when using mechanical microkeratomes have been reported.12 However, few reports on suction loss during flap creation using a femtosecond laser have been presented.13,14

Several methods have been considered and attempted to deal with these complications during flap creation using a microkeratome.5,15–18 However, only a few reports of successful flap creation with good visual outcomes when using a femtosecond laser immediately after the incidence of suction loss have been reported.13,14 Previous reports suggested that when compared to mechanical microkeratomes, femtosecond lasers create more predictable flaps.19 This predictability may be a key factor for success with a second attempted lamellar cut.

We observed step- and line-type stromal bed irregularities after re-cuts in some cases. In a study with fresh porcine cadaver eyes with intentional suction loss during the first cut with a femtosecond laser,20 two cut lines were observed. The first stromal irregularity line was located in the center of the stromal bed and the other was located a distance of approximately two-thirds the stromal bed diameter away from the hinge. The central stromal irregularity line was produced from the first cut and the second irregularity was produced from the second cut.20 The authors did not perform excimer laser ablation after intentional suction loss. Thus, it was unclear whether the lines would disappear after ablation in their study. The authors speculated that these irregularities resulted from differences in applanation pressure, hydration conditions, and/or chemosis.20

Of all eyes with suction loss in our study, including those with residual stromal bed irregularities and multiple suction breaks, 97.2% achieved UDVA of 0.00 logMAR (20/20) or better and 100% of eyes achieved 0.00 logMAR (20/20) of CDVA or better at last follow-up, which varied from 1 day to 3 months after LASIK. No eyes lost CDVA at last follow-up. Furthermore, at 3-month follow-up, no eyes displayed signs of delayed flap complications such as inflammation or haze. Only 19 eyes were available for 3-month follow-up, which is a limitation of our study.

In these cases of suction loss, parts of the cornea underwent two laser passes. In these areas, applied energy on the cornea may have been higher than single passage. However, no clinically significant corneal scarring, haze, or reduction of CDVA was observed in this study. Moreover, those patients who returned for 3-month follow-up did not show any differences in results when compared with patients who underwent uneventful LASIK. These findings suggest that when using a femtosecond laser, re-cutting the flap with an additional attempt after suction loss is safe and effective.

With mechanical microkeratomes, Asano-Kato et al6 reported that suction loss occurred in patients with narrow palpebral fissure, which is typical in Asian populations with significantly flatter keratometric power, especially in younger patients. As suction is applied on the conjunctiva and sclera, patients with particular anatomic characteristics such as flat keratometry may be at increased risk of suction loss in femtosecond laser LASIK as well. To confirm this hypothesis, further study on this relationship should be considered.

Patients’ anxiety related to the surgery may have resulted in difficulty with fixation, head and globe movement, and lid squeezing—all of which may potentially increase the risk of suction loss. We also found the incidence of suction loss was numerically higher in the first operated (right) eye. The lower rate of suction loss in the second eye may be a result of decreased patient anxiety once half of the procedure is completed. The same line of reasoning may hold true for the surgeon’s familiarity with the patient’s anatomy after completing the first eye. Sedation is not used during operations at our clinic. The average age of patients who underwent LASIK during the study period was 33.7 years (range: 17 to 71 years), which was not much different than the average age of those patients who experienced suction loss. A statistically higher rate was noted for male patients and it is conceivable that gender may play a role in patient anxiety levels, lid squeezing, eye movement, and resultant suction loss. Further study is needed to prove this hypothesis.

Our management of intraoperative suction loss was dictated by the stage of the lamellar cut when the suction loss occurred. When suction loss occurred during the raster stage, prior to initiating the side cut, the raster stage was repeated completely from the start with the same diameter and pocket-off setting. When suction loss occurred during the side cut or just before starting the side cut, the raster stage was skipped and the side cut was performed with a smaller diameter. The suction ring was not changed unless it had insufficient suction or was otherwise found defective. We did not change the applanation cones after suction loss. The management of suction loss demonstrated in this study can be applied only for LASIK using the IntraLase FS 60. The technique may differ when other femtosecond lasers are used.

Furthermore, the size of the patient interface used for the IntraLase FS 60 is the same worldwide, with an inner diameter of 13 mm and an outside diameter of 21 mm. The palpebral aperture size is a key factor when properly positioning the suction ring and Asian eyes tend to have narrower palpebral apertures than Caucasian eyes. As a result, we recommend the development of patient interfaces with multiple diameters more appropriate for use with flat keratometric readings, small corneal diameters, and tight interpalpebral fissures. Future models of femtosecond lasers may integrate real time optical coherence tomography, which may increase the reliability of femtosecond-enabled re-cuts in the event of suction loss.

Our results suggest that using a second or third pass with the IntraLase FS 60 after suction loss during flap creation seems to be a safe and effective method for creating the lamellar femtosecond flap. No interval between cuts was required and the immediate re-attempt did not seem to have an adverse effect on visual outcomes.

References

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  3. Al-Mezaine HS, Al-Amro SA, Al-Obeidan S. Incidence, management, and visual outcomes of buttonholed laser in situ keratomileusis flaps. J Cataract Refract Surg. 2009;35(5):839–845. doi:10.1016/j.jcrs.2009.01.013 [CrossRef]
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  9. Llovet F, Galal A, Benitez-del-Castillo JM, Ortega J, Martin C, Baviera J. One-year results of excimer laser in situ keratomileusis for hyperopia. J Cataract Refract Surg. 2009;35(7):1156–1165. doi:10.1016/j.jcrs.2009.03.014 [CrossRef]
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Pre- and Postoperative Visual and Refractive Outcomes in Patients Who Experienced Suction Loss During LASIK Performed With a Femtosecond Laser

Time PointMean±Standard Deviation
UDVA (logMAR) (Snellen)CDVA (logMAR) (Snellen)MRSE (D)
Preoperative (N=71)1.07±0.27 (20/250)−0.23±0.07 (20/12.5)−4.51±1.92
1 day (N=71)−0.19±0.09 (20/16)−0.21±0.08 (20/12.5)0.29±0.41
1 week (n=55)−0.19±0.11 (20/16)−0.23±0.07 (20/12.5)0.19±0.60
3 months (n=19)−0.21±0.09 (20/12.5)−0.23±0.08 (20/12.5)0.14±0.26

Visual and Refractive Outcomes According to Incidence of Suction Loss During LASIK Performed With a Femtosecond Laser

Incidence of Suction LossNo. of Eyes (%)Mean±Standard Deviation
UDVA (logMAR) (Snellen)CDVA (logMAR) (Snellen)MRSE (D)
Within the pupillary border21 (29.2)−0.17±0.103 (20/16)−0.20±0.066 (20/12.5)0.29±0.356
Outside the pupillary border50 (70.4)−0.20±0.083 (20/12.5)−0.22±0.079 (20/12.5)0.16±0.361
Occurred twice4 (5.6)−0.27±0.062 (20/12.5)−0.27±0.062 (20/12.5)−0.04±0.088
Occurred during side cut6 (8.5)−0.20±0.136 (20/12.5)−0.24±0.095 (20/12.5)0.18±0.442
Stromal bed irregularities (steps or lines)5 (6.9)−0.12±0.080 (20/16)−0.15±0.116 (20/16)0.25±0.289
Creation of two side cuts2 (2.8)−0.30±0.000 (20/10)−0.30±0.000 (20/10)−0.15±0.213
Authors

From Shinagawa LASIK Center, Chiyodaku, Tokyo, Japan (Tomita, Watabe, T. Nakamura, N. Nakamura, Tsuru); ReVision Advanced Laser Eye Center, Columbus, Ohio (Waring); and St Joseph’s Translational Research Center, Atlanta, Georgia (Waring).

The authors have no financial or proprietary interests in the materials presented herein.

Correspondence: Minoru Tomita, MD, PhD, Shinagawa LASIK Center, Yurakucho ITOCiA 14F, 2-7-1 Yurakucho, Chiyodaku, Tokyo, 100-0006, Japan. Tel: 81 3 5221 2207; Fax: 81 3 5221 8138; E-mail: tomita@shinagawa.com

Received: December 05, 2010
Accepted: October 11, 2011
Posted Online: December 02, 2011

10.3928/1081597X-20111122-01

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