Fear and anxiety may affect patient cooperation during surgery, with increased risk of complications in uncooperative or fearful patients.1 Therefore, it is of great value to evaluate the patient intraoperative experience to improve preoperative patient counselling. Detailed information of what to expect during surgery may help to reduce patient anxiety and thereby reduce the risk of intraoperative complications. A previous study of LASIK and SMILE has shown patients' experience is more fearful during suction application, laser cutting, and tissue manipulation with LASIK than SMILE.2 However, these findings are limited by the use of comparative groups, where the within-patient variability affects the subjective scores. Hence, a randomized paired-eye study would provide more statistical strength by removing the potential bias of individual characteristics.
The Patient-Reported Outcomes With LASIK (PROWL) study of 574 patients showed that there were no associations between the patients' visual symptoms and corneal aberrations, poor postoperative uncorrected distance visual acuity (UDVA), or the use of contact lenses postoperatively.3 Thus, patients who have laser refractive surgery with excellent Snellen quality may still be unsatisfied due to poor visual quality after surgery.4 This highlights the importance of patients' postoperative visual symptoms as an indicator of a successful refractive procedure.5,6 A few studies of patients treated with SMILE have used a linear scale from 1 to 10 to evaluate the postoperative patient satisfaction and found high satisfaction rates.7–9 However, these scores may give an overall evaluation of the visual outcome without any specification of the patients' visual complaints.
The current randomized, paired-eye study compared the intraoperative patient experience in various stages during SMILE and LASIK. We also compared the postoperative subjective visual symptoms after 1 and 3 months, using a previously validated questionnaire.2,10
Patients and Methods
This study was a prospective, randomized, single-masked, paired-eye, controlled study that included 70 patients between May 2012 and May 2016 at Singapore National Eye Centre.11 Each patient was randomized to undergo SMILE in one eye and LASIK in the other eye on the same day, determined by a computer-generated allocation sequence. A research assistant masked to the study did randomization of LASIK and SMILE for each patient, and the right eye was chosen as the first treated eye. This was a single-masked study, where patients and their caregivers were masked for which treatment was received in each eye.
Our inclusion criteria were as previously published11: 21 years or older, stable refraction for at least 1 year, cycloplegic spherical equivalent of 3.00 diopters (D) or greater in both eyes, cylindrical component of 2.00 D or less in both eyes, anisometropia of 1.00 D or less, and corrected distance visual acuity (CDVA) of 6/12 in both eyes. Patients were excluded if there were clinical or topographic signs of forme fruste keratoconus, severe dry eyes, anterior segment dystrophies, or other ocular conditions except myopia. Patients with diabetes mellitus or undergoing systemic corticosteroid or immunosuppressive treatment were also excluded from the study.
The research was conducted in agreement with the tenets of the Declaration of Helsinki. The study was approved by the Institutional Review Board of Sing-health and registered at clinicaltrials.gov before enrollment of patients (Identifier no: NCT01216475). All patients were thoroughly informed before enrollment, and gave written consent before surgery.
One surgeon (JSM) performed LASIK and SMILE the same day under topical anesthesia. For LASIK, a 7.9-mm flap of 120-µm thickness with a superiorly placed flap hinge was cut with the VisuMax 500-kHz femtosecond laser (Carl Zeiss Meditec, Jena, Germany). An energy index from 28 to 32 (approximately 140 to 160 nJ) was used, with a spot-tracking distance of 4.2 to 4.8 µm for the flap and 1.5 to 2 µm for the side cut. The flap was separated and lifted, followed by ablation in a 6.3- to 7-mm optical zone using the Wave-Light EX500 excimer laser (Alcon Laboratories, Inc., Fort Worth, TX). The transition zone was set to 0.3 mm for spherical corrections and 1.25 mm for astigmatic corrections. After repositioning the flap, postoperative topical medications were applied.
For SMILE, a 7.5-mm cap with a 120-µm cap thickness was created using the VisuMax 500-kHz laser in the following sequence: posterior surface cut in a spiral-in pattern, lenticule edge vertical cut, anterior surface cut spiral-out pattern, and a superior positioned incision for lenticule removal. The energy index was 29 to 32 (approximately 145 to 160 nJ) with a laser spot-track distance of 3 to 4.5 µm for the cap and 2 to 2.2 µm for the lenticule. Minimum lenticule thickness was 15 µm with a lenticule diameter of 6.3 to 6.5 mm. The lenticule edge was located in the incision and the remaining tissue bridges were gently broken with a SMILE dissector (AE2403 LLC; Asico, Westmont, IL). The lenticule was grasped and removed though the small incision with a pair of forceps.
Both LASIK and SMILE were sequentially performed in the same operating room, where the VisuMax and WaveLight 500EX lasers were positioned next to each other. The patient underwent surgery on the right eye first for either SMILE or LASIK. Patients then left the room to answer questions about their experience on that eye. They then entered the same room to have the surgery performed on the left eye. The patients were masked as to which eye was having which surgery; the randomization was only known to the surgeon. The person documenting the questionnaire evaluation was also masked with respect to which procedure was performed on which eye. Patients were counselled before the surgery, at the clinic appointment, about the differences between SMILE and LASIK, but not on the day of surgery. On the day of surgery, they were just told to follow instruction with respect to fixation for each eye. Slit-lamp examination was only performed after both procedures were completed after the intraoperative questionnaire. Questions regarding the first treated eye (right eye) were answered before proceeding with surgery of the contralateral eye and subsequently finalization of the questionnaire.
The postoperative regimen included moxifloxacin hydrochloride 0.5% (Vigamox; Alcon Laboratories, Inc.) and dexamethasone 0.1% eye drops (Maxidex; Alcon Laboratories, Inc.) four times a day for 2 weeks. Artificial tears were prescribed, and the patients were encouraged to use them initially every hour for the first week and thereafter as needed. Postoperative examination was done at 1 day, 1 week, and 1 and 3 months after surgery. A total of 18 and 7 eyes treated by LASIK and SMILE, respectively, used a bandage contact lens postoperatively.
Intraoperative and postoperative questionnaires were developed from a standardized questionnaire that had previously been used to evaluate patient experience after laser refractive procedures.2,10
The intraoperative questionnaire included light perception, ability to fixate, and level of anxiety, discomfort, and fear at various stages during surgery. The questionnaire consisted of dichotomous yes/no questions combined with Likert scale grading to describe level of anxiety (1 = none, 5 = extreme), discomfort (1 = none, 5 = very severe), and fear (1 = none, 6 = extreme).
The postoperative questionnaire was completed at the 1- and 3-month follow-up and included light sensitivity, eye discomfort, eye dryness, excessive tearing, gritty sensation, glare, halos, blurring, and fluctuations in vision (1 = not at all, 6 = very severe/extremely). Severity of headache and night driving problems were also registered at the 1- and 3-month examinations for each patient, but it was not possible to evaluate for each eye.
Sample size was calculated from a previous study of patients treated with LASIK and SMILE that used the same questionnaires as the current study.2 To confirm a non-inferiority limit of 0.6 in mean postoperative symptom scores with an assumed standard deviation of 1.2, power of 80%, and significance level of 2.5%, the sample size should consist of a minimum of 63 patients (126 eyes). The standard deviation was set high in our calculations, given that the range for standard deviations has been reported to be between 0.5 and 1.3 for the evaluated postoperative symptoms.2 Statistical analysis was performed in SPSS for Windows software (version 19.0; SPSS, Inc., Chicago, IL). Descriptive data were presented as mean ± standard deviation and range. The Mann–Whitney U and Wilcoxon signed-rank tests were used to compare continuous variables and chi-square and Fisher's exact tests for categorical values. A P value of less than .05 was considered statistically significant.
All 70 enrolled patients completed the intraoperative questionnaire after LASIK and SMILE. Postoperatively, 63 and 58 patients completed the 1- and 3-month questionnaires, respectively. Demographics and preoperative refractive data are listed in Table 1.
Suction loss occurred in 3 patients, with two occurring during treatment of the first eye. One patient experienced suction loss as the rim was being cut during LASIK. The patient was rescheduled the next day to perform a rim cut and surgery was completed without complications. Two patients experienced suction loss during SMILE, during the cutting of the anterior lenticule surface. Immediate redocking was performed and the procedure was completed the same day.12
Results from the intraoperative questionnaire are shown in Figure 1 and Table A (available in the online version of this article). Related to the visual experience during surgery, the incidence of complete blackout during docking (P = .205) and laser cutting (P = .222) was at the same level in eyes treated with SMILE and LASIK. Patients experienced less discomfort during flap lifting in LASIK than tissue manipulation in SMILE (1.59 ± 0.8 vs 1.9 ± 0.9, P = .020) but equally during docking (P = .837) and laser cutting (P = .250). Excimer ablation in LASIK was the most frightening part of the two surgical procedures, with an average score of 3.8 ± 1.7, between “moderately” and “very much.” Docking and suction was a significantly more fearful experience during LASIK than SMILE (3.4 ± 1.9 vs 2.6 ± 1.6, P = .024).
Intraoperative subjective patient experience. (A) Anxiety and discomfort scores (0 = none to 5 = extremely/very severe). (B) Fear scores (1 = least fearful to 6 = extremely fearful). Asterisk marks significant differences (P < .05). SMILE = small incision lenticule extraction
Patients with intraoperative suction loss had increased fear throughout the procedure, ranging from a score of 2.0 ± 1.7 during docking to 4.7 ± 2.3 during flap lifting/tissue manipulation (Table A, n = 3).
The right eye was the first treated eye in all patients and independent of the randomization. We compared right and left eye scores for LASIK and SMILE separately to evaluate the effect of the first time surgical experience (data not shown). In LASIK, the grade of discomfort during laser flap cutting was slightly higher in the first treated eye, with a score of 1.9 ± 0.9 in the right eye and 1.4 ± 0.6 in the left eye (P = .006), whereas the remaining grades related to intraoperative experience was similar (P ≥ .174). There were no significant differences in the average scores between right and left eyes treated with SMILE (P ≥ .150).
Development of Postoperative Symptoms: 1 Versus 3 Months
The average 1- and 3-month postoperative scores were compared in LASIK and SMILE to evaluate the development of the visual symptoms (Figure 2 and Table B, available in the online version of this article). The analysis comprised 53 patients because both the 1- and 3-month questionnaires had to be completed.
Postoperative visual symptoms after (A) LASIK and (B) small incision lenticule extraction (SMILE), scored from 0 = none to 5 = extremely/very severe. Asterisk marks significant differences (P < .05).
Comparison of the Postoperative Symptom Scores: 1 vs 3 Months,
In LASIK, the postoperative symptoms related to visual quality decreased significantly from 1 to 3 months in terms of light sensitivity (P = .045), eye discomfort (P = .019), eye dryness (P = .009), gritty sensation (P = .030), and fluctuations in vision (P = .034). In SMILE, there was a significant reduction in light sensitivity (P = .034), eye discomfort (P = .034), blurring (P = .038), and fluctuations in vision (P = .022) (Table B). Reported severity of driving problems at night and headache was comparable at 1 and 3 months, evaluated on a patient basis but not separately for the two surgical procedures (P = .429 and .109, Table B).
Comparison of Postoperative Symptoms: Lasik Versus Smile
The comparisons of the average scores in LASIK and SMILE at 1 and 3 months are shown in Figure 3 and Table C (available in the online version of this article). At 1 month, visual blurring was less severe in eyes treated with LASIK compared to SMILE, with an average score of 1.8 ± 0.7 and 2.1 ± 0.8, respectively (P = .025). However, the severity of visual blurring returned to similar levels at 3 months, with an average score of 1.78 ± 0.7 for LASIK and 1.86 ± 0.8 for SMILE (P = .600). The remaining evaluated visual symptoms (light sensitivity, eye discomfort, eye dryness, excessive tearing, gritty sensation, glare, halos, and fluctuations in vision) were equally scored in eyes treated with LASIK and SMILE at the 1- and 3-month examinations (P ≥ .339, Table C and Figure 3).
Postoperative visual symptoms at (A) 1 and (B) 3 months, scored from 0 = none to 5 = extreme. Asterisk marks significant differences (P < .05). PTK = phototherapeutic keratectomy; CDVA = corrected distance visual acuity; SMILE = small incision lenticule extraction
Comparison of the Postoperative Symptom Scores: LASIK vs SMILE,
This prospective, randomized, paired-eye study aimed to evaluate the intraoperative and postoperative patient experience in LASIK and SMILE by a standardized validated questionnaire.2,10 Patients experienced more discomfort during tissue manipulation in SMILE than flap lifting in LASIK, whereas docking and laser application seemed equally uncomfortable for the patients. Interestingly, the patients still feared the initial docking and suction more in LASIK than SMILE, although the level of discomfort was similar for the two refractive procedures. Initial visual blurring was present after SMILE at 1 month, but resolved to a level seen after LASIK at 3 months.
Previous studies have described the intraoperative patient experience of LASIK where the corneal flap was created with either a microkeratome13,14 or femtosecond laser.2,10,13 A contralateral eye study of LASIK using the Zyoptix XP microkeratome (Bausch & Lomb, Rochester, NY) and the Intralase 60-kHz laser found no significant differences in levels of fear between the two surgical procedures.13 However, a contralateral eye study of LASIK with the Intralase 60-kHz laser and VisuMax 500-kHz laser reported that patients experienced docking and suction as more frightening with the 60-kHz laser.10 The reported fear scores for the LASIK 500-kHz group were comparable to our current findings. Because the intraoperative intraocular pressure during suction is higher with the 60-kHz laser than with the 500-kHz laser, it may cause more fear in the patients, whereas the intraoperative intraocular pressure is the same in LASIK and SMILE.15
To our knowledge, only one comparative group study has evaluated the intraoperative patient experience after LASIK and SMILE.2 Using a questionnaire identical to our study, patients scored LASIK as a more frightening procedure than SMILE in terms of docking and suction (3.5 ± 1.9 vs 2.4 ± 1.4), laser cutting (3.5 ± 1.2 vs 2.4 ± 0.8), and flap lifting/tissue manipulation (3.7 ± 1.4 vs 2.8 ± 1.3). However, the statistical comparison is sensitive to the between-subject variability, where a higher level of anxiety in one of the compared groups would cause a significant difference in fear scores. Our paired-eye study eliminated the between-subject variability and may explain why the fear score was only higher for LASIK during docking and suction (3.4 ± 1.9 vs 2.6 ± 1.6).We performed all SMILE and LASIK treatments with the VisuMax femtosecond laser using a small S-size contact glass and identical procedures for alignment, docking, and suction.16 Therefore, it is somewhat surprising that patients experienced more fear during the initial stage of docking and suction in LASIK compared to SMILE. The patients were masked with regard to the treatment, but did have prior knowledge of flap creation in LASIK.2 Uncertainty and anxiety may cause more fear during surgery of the first treated eye (in this study it was the right eye). However, we found that docking and suction in LASIK was equally frightening in the right and left treated eyes. Furthermore, slightly more patients received LASIK as their second treatment due to randomization.
Interestingly, the tissue manipulation in SMILE was more uncomfortable than flap lifting in LASIK, although both average scores were less than 2 (mild). We did not find it necessary to use any globe stabilization during dissection and removal of the lenticule in SMILE.11 However, the forced eye movement during dissection and especially during loosening of the lenticule edge may be slightly more uncomfortable than flap lifting in LASIK. Although the surgeon in this study was experienced in both procedures, the lenticule extraction still takes a slightly longer time than flap lifting. Hence, inexperienced SMILE surgeons may consider applying more topical anesthesia until their surgical time is reduced to lessen the patients' intraoperative discomfort. The patients in this study did not receive any mild anxiolytic or sedative prior to surgery, but some surgeons do use them routinely preoperatively.17
Patients with suction loss during surgery experienced almost all stages of surgery as more frightening than patients with uncomplicated surgery, although the group was too small for statistical comparison. However, it highlights the importance of detailed counselling of what to expect during the surgical procedure to reduce the patients' intraoperative fearfulness. Also, patient anxiety during preoperative consultation must be considered as a relative contra-indication for surgery due to the increased risk of intraoperative complications.
From the patients' subjective evaluation of postoperative visual symptoms, we found that blurring at 1 month was worse after SMILE than LASIK. However, blurring decreased to a score of 1.86 ± 0.8 in SMILE and 1.78 ± 0.7 in LASIK after 3 months, with no difference between the two laser refractive procedures. Additionally, all remaining visual symptoms were similar after LASIK and SMILE at 3 months. Patients with and without suction loss were the same in terms of postoperative visual scores. Previous studies of femtosecond laser–assisted LASIK have used a linear scoring system to assess the postoperative subjective satisfaction and found high patient satisfaction rates of 88% to 95% that would recommend LASIK to friends and relatives.18–21 Although useful for an overall evaluation of the surgical outcome, this does not specify what the patients are satisfied with (eg, their visual outcome or living without glasses and contact lenses).
Another aspect for consideration has been the subjective dry eye symptoms after LASIK, which are caused by nerve damage and reduced corneal sensitivity after flap creation.22–24 Prior studies have used the Ocular Surface Disease Index (OSDI) to assess subjective dry eye symptoms (ocular symptoms, vision-related functions, and environmental triggers) and found increased postoperative scores up to 3 months after surgery, gradually decreasing thereafter.25–27 Questions related to ocular symptoms in the OSDI were almost similar to those from our study (light sensitivity, gritty sensation, eye discomfort, blurring, and fluctuations in vision). Because we aimed to describe the severity and development of the postoperative visual symptoms, we chose to evaluate each symptom with one individual score instead of using an overall score for the visual quality. Furthermore, the mentioned study enrolled patients with good pre-operative tear functionality, whereas we could not rule out that some of our patients had borderline dry eye symptoms prior to surgery.
Our study demonstrated that the initial visual blurring 1 month after SMILE improved at 3 months to a level seen after LASIK. Furthermore, there were no significant differences in any of the subjective symptoms at 3 months. The results are consistent with previous questionnaire group studies of patients treated with SMILE and LASIK,2,8 although 3-month postoperative glare in one study was more severe after LASIK (2.84 ± 0.79 vs 1.96 ± 0.73; range: 0 [none] to 4 [severe]).8 The fact that SMILE induced more subjective blurring at 1 month may seem counterintuitive because flap-free SMILE preserves the sub-basal nerve fibers28,29 and, in some studies, was associated with fewer dry eye symptoms.22,29 One possible answer to this question lies in the interface, where tissue removal from an enclosed space causes disarrangements of the stromal collagen fibrils.30,31 Clinical studies of LASIK and SMILE have reported significantly higher light scattering up to 6 months after SMILE.32,33 The initial light scattering and blurring in SMILE may be related to interface irregularities; hence a smooth lenticule dissection is important for the visual outcome34 together with continuous optimization of the femtosecond laser energy settings.35 It is important to note that we did find similar postoperative visual symptoms 3 months after surgery, although significantly different levels of light scattering can be present up to 6 months after LASIK and SMILE.32,33
Although a randomized, paired-eye, patient-masked study allows for the most objective comparison between eyes with regard to a patient's subjective experience, our study still has some limitations. A double-masked study would be preferable to avoid physician-related bias, but was not practically possible. The allocated procedure was easy to recognize during slit-lamp examination, and LASIK requires the use of two lasers instead of one. Patients may have had prior knowledge of the procedures and may have guessed the allocation of LASIK and SMILE. However, the remaining personnel (nurses and optometrists) who participated in the postoperative follow-up, including the questionnaire, were masked. The time of tissue manipulation during LASIK and SMILE was not measured in this study, although longer surgical intervention may contribute to an increased level of fear. To compensate for this, the surgeon was as adept in performing SMILE as he was in performing LASIK before initiation of the study. We also recognize that our patient group with suction loss was too small for statistical comparison,12 although there was a tendency toward higher levels of fear and discomfort than in the group with uncomplicated refractive surgery. The questionnaire used for this study has been validated in previous patients treated with SMILE and LASIK at Singapore National Eye Centre, but future studies may focus on validation of the used questionnaire in populations outside Singapore. The questionnaire can be accessed by contacting the corresponding author for a copy.
This randomized, paired-eye study found that SMILE was not inferior to LASIK in terms of intraoperative fear and anxiety, although tissue manipulation was more uncomfortable in SMILE than LASIK. Reported visual blurring at 1 month was worse in eyes treated with SMILE than those treated with LASIK, but improved at 3 months to a similar level as seen after LASIK. The evaluated postoperative visual symptoms were similar in eyes treated with LASIK and SMILE at 3 months. Future studies may explore the intraoperative and postoperative subjective visual symptoms in patients who experienced suction loss.
- Ivarsen A, Asp S, Hjortdal J. Safety and complications of more than 1500 small-incision lenticule extraction procedures. Ophthalmology. 2014;121:822–828. doi:10.1016/j.ophtha.2013.11.006 [CrossRef]
- Ang M, Ho H, Fenwick E, et al. Vision-related quality of life and visual outcomes after small-incision lenticule extraction and laser in situ keratomileusis. J Cataract Refract Surg. 2015;41:2136–2144. doi:10.1016/j.jcrs.2015.10.049 [CrossRef]
- Eydelman M, Hilmantel G, Tarver ME, et al. Symptoms and satisfaction of patients in the patient-reported outcomes with laser in situ keratomileusis (PROWL) studies. JAMA Ophthalmol. 2017;135:13–22. doi:10.1001/jamaophthalmol.2016.4587 [CrossRef]
- Levinson BA, Rapuano CJ, Cohen EJ, Hammersmith KM, Ayres BD, Laibson PR. Referrals to the Wills Eye Institute Cornea Service after laser in situ keratomileusis: reasons for patient dissatisfaction. J Cataract Refract Surg. 2008;34:32–39. doi:10.1016/j.jcrs.2007.08.028 [CrossRef]
- Tuan KA. Visual experience and patient satisfaction with wavefront-guided laser in situ keratomileusis. J Cataract Refract Surg. 2006;32:577–583. doi:10.1016/j.jcrs.2006.01.002 [CrossRef]
- Bühren J, Martin T, Kühne A, Kohnen T. Correlation of aberrometry, contrast sensitivity, and subjective symptoms with quality of vision after LASIK. J Refract Surg. 2009;25:559–568.
- Vestergaard A, Ivarsen AR, Asp S, Hjortdal JØ. Small-incision lenticule extraction for moderate to high myopia: predictability, safety, and patient satisfaction. J Cataract Refract Surg. 2012;38:2003–2010. doi:10.1016/j.jcrs.2012.07.021 [CrossRef]
- Ganesh S, Gupta R. Comparison of visual and refractive outcomes following femtosecond laser-assisted LASIK with SMILE in patients with myopia or myopic astigmatism. J Refract Surg. 2014;30:590–596. doi:10.3928/1081597X-20140814-02 [CrossRef]
- Sekundo W, Kunert KS, Blum M. Small incision corneal refractive surgery using the small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism: results of a 6 month prospective study. Br J Ophthalmol. 2011;95:335–339. doi:10.1136/bjo.2009.174284 [CrossRef]
- Hall RC, Rosman M, Chan C, Tan DT, Mehta JS. Patient and surgeon experience during laser in situ keratomileusis using 2 femtosecond laser systems. J Cataract Refract Surg. 2014;40:423–429. doi:10.1016/j.jcrs.2013.08.056 [CrossRef]
- Ang M, Tan D, Mehta JS. Small incision lenticule extraction (SMILE) versus laser in-situ keratomileusis (LASIK): study protocol for a randomized, non-inferiority trial. Trials. 2012;13:75. doi:10.1186/1745-6215-13-75 [CrossRef]
- Wong CW, Chan C, Tan D, Mehta JS. Incidence and management of suction loss in refractive lenticule extraction. J Cataract Refract Surg. 2014;40:2002–2010. doi:10.1016/j.jcrs.2014.04.031 [CrossRef]
- Tan CS, Au Eong KG, Lee HM. Visual experiences during different stages of LASIK: Zyoptix XP microkeratome vs Intralase femtosecond laser. Am J Ophthalmol. 2007;143:90–96. doi:10.1016/j.ajo.2006.08.023 [CrossRef]
- Srivannaboon S, Chansue E. Intraoperative perception and sensation in laser in situ keratomileusis (LASIK). J Med Assoc Thai. 2004;87:419–421.
- Strohmaier C, Runge C, Seyeddain O, et al. Profiles of intraocular pressure in human donor eyes during femtosecond laser procedures: a comparative study. Invest Ophthalmol Vis Sci. 2013;54:522–528. doi:10.1167/iovs.12-11155 [CrossRef]
- Shah R, Shah S. Effect of scanning patterns on the results of femtosecond laser lenticule extraction refractive surgery. J Cataract Refract Surg. 2011;37:1636–1647. doi:10.1016/j.jcrs.2011.03.056 [CrossRef]
- Verdaguer P, El-Husseiny MA, Elies D, et al. Small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism. Journal of Emmetropia. 2013;4:191–196.
- Tanzer DJ, Brunstetter T, Zeber R, et al. Laser in situ keratomileusis in United States Naval aviators. J Cataract Refract Surg. 2013;39:1047–1058. doi:10.1016/j.jcrs.2013.01.046 [CrossRef]
- Price MO, Price DA, Bucci FA Jr, Durrie DS, Bond WI, Price FW Jr, . Three-year longitudinal survey comparing visual satisfaction with LASIK and contact lenses. Ophthalmology. 2016;123:1659–1666. doi:10.1016/j.ophtha.2016.04.003 [CrossRef]
- Hashmani S, Hashmani N, Rajani H, et al. Comparison of visual acuity, refractive outcomes, and satisfaction between LASIK performed with a microkeratome and a femto laser. Clin Ophthalmol. 2017;11:1009–1014. doi:10.2147/OPTH.S137451 [CrossRef]
- Ganesh S, Brar S. Femtosecond intrastromal lenticular implantation combined with accelerated collagen cross-linking for the treatment of keratoconus: initial clinical result in 6 eyes. Cornea. 2015;34:1331–1339. doi:10.1097/ICO.0000000000000539 [CrossRef]
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- Agca A, Cankaya KI, Yilmaz I, et al. Fellow eye comparison of nerve fiber regeneration after SMILE and femtosecond laser-assisted LASIK: a confocal microscopy study. J Refract Surg. 2015;31:594–598. doi:10.3928/1081597X-20150820-04 [CrossRef]
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|Characteristic||SMILE (n = 70)||LASIK (n = 70)||Pb|
|Age (y)||28.3 ± 5.21 (21 to 45)|
| ≤35||64 (91%)|
| >35||6 (9%)|
| Male||25 (36%)|
| Female||45 (64%)|
| White||2 (3%)|
| Black||0 (0%)|
| Asian||67 (96%)|
| Other||1 (1%)|
|Treatment right eye||40 (57%)||30 (43%)|
|Treatment sphere (D)||−4.97 ± 1.52 (−9.25 to −2.00)||−4.99 ± 1.46 (−8.75 to −2.25)||.718|
|Treatment cylinder (D)||−0.77 ± 0.60 (−2.50 to 0.00)||−0.80 ± 0.62 (−2.50 to 0.00)||.703|
|Treatment SE (D)||−5.26 ± 1.62 (−9.50 to −2.00)||−5.40 ± 1.59 (−9.50 to −2.25)||.683|
|Intraoperative Symptom||LASIK (n = 70)||SMILE (n = 70)||Pc||Suction Loss (n = 3)||No Suction Loss (n = 137)|
|Symptoms related to visual experience (yes/no)|
| Docking blackout||11 (15.7%)||17 (24.3%)||.205||1 (33.3%)||27 (19.7%)|
| Flap cutting blackout||8 (11.4%)||13 (18.8%)||.222||1 (50.0%, n = 2)||20 (14.6%)|
| Light seen during most of the flap cutting procedure||68 (98.6%)||63 (90.04%)||.063||2 (66.7%)||129 (94.9%)|
|Patients' discomfort scores (scale = 1 to 5)|
| Docking and suction||1.76 ± 0.9||1.79 ± 0.9||.837||2.7 ± 2.1||1.8 ± 0.9|
| Laser flap cutting||1.7 ± 0.8||1.9 ± 0.9||.250||3.0 ± 1.7||1.8 ± 0.8|
| Flap lifting/tissue manipulation||1.59 ± 0.8||1.9 ± 0.9||.020||2.7 ± 2.1||1.7 ± 0.9|
|Patients' preoperative anxiety scores (scale = 1 to 5)|
| Vacuum application||2.04 ± 0.9||2.07 ± 1.0||.935||3.3 ± 2.1||2.0 ± 0.9|
| Flap cutting visual experience||1.96 ± 0.9||2.1 ± 0.9||.341||2.7 ± 1.5||2.0 ± 0.9|
|Patients' intraoperative fear scores (scale = 1 to 6)|
| Applying suction ring||3.4 ± 1.9||2.6 ± 1.6||.024||2.0 ± 1.7||3.1 ± 1.8|
| Blackout||2.1 ± 1.1 (n = 49)||2.2 ± 1.3 (n = 53)||.768||3.0 ± 2.6||2.1 ± 1.1|
| Laser flap cutting||3.7 ± 1.7||3.3 ± 1.6||.096||4.0 ± 1.7||3.5 ± 1.6|
| Flap lifting/tissue manipulation||3.2 ± 1.4||3.4 ± 1.4||.365||4.7 ± 2.3||3.3 ± 1.4|
| Excimer laser ablation||3.8 ± 1.7||N/A||4.0 (n = 1)||3.6 ± 1.8|
| Flap replacement||3.0 ± 1.7||N/A||5.0 (n = 1)||2.7 ± 1.7|
Comparison of the Postoperative Symptom Scores: 1 vs 3 Monthsa,b
|1 Month (n = 53)||3 Months (n = 53)||Pc||1 Month (n = 53)||3 Months (n = 53)||Pc|
|Light sensitivity||2.3 ± 0.8||2.02 ± 0.7||.045||1.98 ± 0.8||2.2 ± 0.9||.034|
|Eye discomfort||1.92 ± 0.8||1.65 ± 0.6||.019||1.94 ± 0.8||1.7 ± 0.6||.034|
|Eye dryness||2.6 ± 0.9||2.28 ± 0.8||.009||2.36 ± 0.8||2.19 ± 0.7||.108|
|Excessive tearing||1.3 ± 0.6||1.34 ± 0.6||.796||1.34 ± 0.6||1.36 ± 0.6||.819|
|Gritty sensation||1.7 ± 0.8||1.45 ± 0.7||.030||1.55 ± 0.6||1.38 ± 0.6||.088|
|Glare||1.83 ± 0.7||1.7 ± 0.7||.269||1.89 ± 0.6||1.77 ± 0.7||.405|
|Halos||1.66 ± 0.7||1.53 ± 0.8||.144||1.68 ± 0.7||1.6 ± 0.7||.346|
|Blurring||1.89 ± 0.8||1.79 ± 0.7||.336||2.15 ± 0.9||1.9 ± 0.8||.038|
|Fluctuations in vision||2.02 ± 0.8||1.8 ± 0.8||.034||2.19 ± 0.9||1.89 ± 0.8||.022|
|Headaches, more than usuald||1.66 ± 0.8||1.49 ± 0.8||.109||1.66 ± 0.8||1.49 ± 0.8||.109|
|Night driving problemsd||1.21 ± 0.5||1.34 ± 0.8||.429||1.21 ± 0.5||1.34 ± 0.8||.429|
Comparison of the Postoperative Symptom Scores: LASIK vs SMILEa,b
|Postoperative Symptom||1 Month||3 Months|
|LASIK (n = 63)||SMILE (n = 63)||Pc||LASIK (n = 58)||SMILE (n = 63)||Pc|
|Light sensitivity||2.29 ± 0.7||2.20 ± 0.9||.632||1.97 ± 0.8||1.95 ± 0.8||.834|
|Eye discomfort||1.89 ± 0.7||1.95 ± 0.8||.640||1.64 ± 0.6||1.66 ± 0.6||.871|
|Eye dryness||2.49 ± 0.9||2.30 ± 0.8||.354||2.20 ± 0.8||2.16 ± 0.7||.648|
|Excessive tearing||1.30 ± 0.6||1.30 ± 0.5||.897||1.30 ± 0.5||1.34 ± 0.6||.697|
|Gritty sensation||1.68 ± 0.8||1.54 ± 0.6||.339||1.45 ± 0.7||1.40 ± 0.6||.791|
|Glare||1.80 ± 0.7||1.84 ± 0.9||.956||1.67 ± 0.7||1.78 ± 0.7||.454|
|Halos||1.70 ± 0.7||1.70 ± 0.8||.864||1.50 ± 0.6||1.59 ± 0.7||.510|
|Blurring||1.80 ± 0.7||2.10 ± 0.8||.025||1.78 ± 0.7||1.86 ± 0.8||.600|
|Fluctuations in vision||2.10 ± 0.8||2.20 ± 0.9||.402||1.78 ± 0.8||1.86 ± 0.9||.617|