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AIM:To evaluate corrective effect and stability of corneal morphology in patients with moderate to high myopia after 2a treatment of femtosecond laser assisted laser in situ keratomileusis(FS-LASIK)Xtra.METHODS:Retrospective case-control study. A total of 30 cases(58 eyes)Patients with moderate to high myopia combined with astigmatism who planned to undergo refractive surgery in our hospital from August 2019 to August 2020 were included, and different types of surgery were performed respectively based on the relevant index of keratoconus screening in the preoperative corneal topography. They were divided into FS-LASIK group and Xtra group, with 15 cases(29 eyes)in each group. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), spherical equivalent(SE)and the corneal curvature of the anterior and posterior surfaces of different diameters(3, 5 and 7 mm)measured by Sirius three-dimensional corneal topography were observed preoperatively and 3 mo, 1 and 2 a postoperatively.RESULTS: The UCVA of the two groups of patients at different time points after surgery was significantly increased compared with preoperatively(both P<0.01), and there was no difference in UCVA and SE between the two groups(P>0.05). After 2 a postoperatively, residual astigmatism was -0.25-0 D in 25 eyes(86%)of the FS-LASIK Xtra group and 24 eyes(83%)of the FS-LASIK group. The actual corrected SE and expected corrected SE of both groups were positively correlated(both P<0.05). There were differences in corneal curvature on the surface of different diameter areas(3, 5, and 7 mm)between the two groups at 3 mo, 1, and 2 a postoperatively compared with preoperatively. After 1 and 2 a postoperatively, the corneal posterior surface curvature of the FS-LASIK Xtra group with corneal diameter of 3 and 5 mm was higher than that of the FS-LASIK group(P<0.05).CONCLUSIONS:FS-LASIK Xtra has good safety, efficacy and predictability in correcting patients with moderate to high myopia.
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AIM: To explore the clinical effect of small incision lenticule extraction(SMILE)on the treatment of myopic anisometropia.METHODS: Clinical data of 76 patients(146 eyes)with myopic anisometropia who received SMILE or femtosecond assisted laser in situ keratomileusis(FS-LASIK)in our hospital from January 2021 to December 2022 were retrospectively analyzed. The patients were divided into SMILE group(39 cases, 77 eyes)and FS-LASIK group(37 cases, 69 eyes)according to surgical methods. Uncorrected visual acuity(UCVA), diopter, anisometropia, corneal aberration and occurrence of postoperative complications were compared between the two groups at 1 wk, 1 and 3 mo after surgery.RESULTS: The UCVA of the two groups was improved after surgery compared with that before surgery, and the coma, trefoil, spherical aberration and total higher-order aberration were significantly increased compared to those before surgery(P<0.05), and the coma, trefoil, spherical aberration and total higher-order aberration in the FS-LASIK group were significantly higher than those in the SMILE group(P<0.05). After follow-up to 3 mo after surgery, the incidence of postoperative complications was significantly lower in the SMILE group than that in the FS-LASIK group(5.2% vs 15.9%, P<0.05).CONCLUSION: Both SMILE and FS-LASIK can effectively enhance the UCVA and improve the visual quality in patients with myopic anisometropia, but SMILE has lower corneal higher order aberrations, lower incidence of postoperative complications and better overall effect.
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AIM: To explore the effects of femtosecond laser-assisted cataract surgery combined with intraocular lens implantation(FLACS-IOL)on postoperative deviation rate of multifocal intraocular lens(MIOL)and visual quality in cataract patients.METHODS: In the prospective study, 95 patients with cataract(108 eyes)who underwent MIOL implantation in the hospital between January 2021 and December 2022 were enrolled. According to different surgical methods, they were divided into FLACS group(51 cases, 56 eyes)and Phaco group(44 cases, 52 eyes). The operation time, incision diameter of anterior capsule, effective phaco time(EPT), cumulative dissipated energy(CDE), uncorrected distance visual acuity(UCDVA), best corrected distance visual acuity(BCDVA), eccentricity distance of IOL and deviation rate at 3 mo after surgery, total high order aberration(HOA), Trefoil and coma under 3 mm pupil were compared between the two groups.RESULTS: The operation time in the FLACS group was significantly shorter than that in the Phaco group, EPT and CDE were significantly lower than those in the Phaco group(all P<0.05). There was no significant difference in incision diameter of anterior capsule between the two groups(P>0.05). At 1 wk, 3 mo after surgery, UCDVA in the FLACS group was better than that in the Phaco group(all P<0.05). There were significant difference in UCDVA at 1 wk, 3 mo after surgery or BCDVA at 3 mo after surgery between the two groups(P<0.05). At 3 mo after surgery, eccentricity distance of IOL in the FLACS group was shorter than that in the Phaco group, and deviation rate was significantly lower than that in the Phaco group(all P<0.05). Under pupil diameter of 3 mm, HOA, trefoil and coma of whole eyes were decreased in both groups at 3 mo after surgery(P<0.05). At 3 mo after surgery, there were significant differences in HOA and trefoil of whole eyes between the FLACS group and Phaco group(P<0.05), but there was no significant difference in coma at 3 mo after surgery(P>0.05).CONCLUSION: FLACS-IOL can effectively reduce deviation rate of IOL and obtain better visual quality in cataract patients.
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Keratoconus is a chronic non-inflammatory corneal disease characterized by thinning and localized protrusion of the corneal stroma in a conical shape. It often leads to irreversible irregular astigmatism and varying degrees of decline in corrected visual acuity. With the rise of femtosecond laser refractive surgery, corneal lenses were discovered as a good biological material. Corneal lens implantation of the cornea can increase the thickness of the cornea and delay the progression of keratoconus disease for further treatment. Currently, convex lenses obtained from myopic small incision lenticule extraction(SMILE)surgery and concave lenses obtained from farsighted SMILE surgery, as well as parallel lenses obtained from donors, can be implanted into the cornea with the aid of femtosecond lasers as lens materials. This article will summarize and discuss the above three lens material implantation methods to provide reference for the selection of keratoconus treatment.
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Purpose: To identify the facial anthropometric parameters that predict the difficulty during femtosecond (FS) laser. Methods: This was a single?center observational study was conducted on participants between the ages 18 and 30 years who were planned for FS?LASIK (femtosecond laser?assisted laser in situ keratomileusis) or SMILE (small incision lenticule extraction) at Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India. The front and side?facing images of the participants were analyzed using Image J software to measure different anthropometric parameters. The nasal bridge index, facial convexity, and other parameters were measured. The difficulty faced by the surgeon during docking was recorded for each subject. The data were analyzed on Stata 14. Results: A total of 97 subjects were included. The mean age was 24 (±7) years. Twenty?three (23.71%) subjects were females while the rest were males. Difficulty in docking was seen in 1 (4.34%) female and 14 (19%) males. The mean nasal bridge index was 92.58 (±4.01) in subjects with deep?set eyes and 89.72 (±4.30) in normal subjects. The mean total facial convexity was 129.28 (±4.24) in deep?set eyes, and 140.23 (±4.74) in normal subjects. Conclusion: Total facial convexity appeared as the most important feature, with the value being less than 133° in most subjects with unfavorable facial anthropometry
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Purpose: To compare the visual outcomes in patients undergoing small?incision lenticule extraction (SMILE) for correction of myopic astigmatism (??1.50 D) with or without manual cyclotorsion compensation. Methods: A prospective, double?blinded, randomized, contralateral study was conducted in the refractive services of a tertiary eye care center. Eligible patients with bilateral high myopic astigmatism (?1.5 D) and intraoperative cyclotorsion (?5°) undergoing SMILE between June 2018 and May 2019 were included. Cyclotorsion compensation was performed using triple centration method before femtosecond laser delivery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) measurement, manifest refraction, slit?lamp biomicroscopy, and corneal tomography were performed preoperatively and at 1 and 3 months’ postoperative visit. Astigmatic outcomes were analyzed using Alpins criteria. Results: A total of 30 patients (60 eyes) were included in this study. The patients underwent bilateral SMILE surgery, with manual cyclotorsion compensation in one eye (CC group, n = 30 eyes) and no cyclotorsion compensation in the other eye (NCC group, n = 30 eyes). Preoperative astigmatism and intraoperative cyclotorsion were ?2.0 D and 7.03° ± 1.06° (CC) and ?1.75 D and 7.24° ± 0.98° (NCC) (P = 0.472 and 0.240, respectively). No significant differences were noted in mean refractive spherical equivalent (MRSE), UDVA, CDVA, and refractive error between the two groups at 3 months’ postoperative visit. Astigmatic outcomes measured using Alpins criteria demonstrated no significant difference between the two cohorts. Conclusion: The cyclotorsion compensation technique provided no additional advantage in terms of astigmatic outcomes or postoperative visual quality, in eyes with high preoperative astigmatism and intraoperative cyclotorsion.
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Purpose: To compare visual outcomes of early enhancement following small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK). Methods: Retrospective analysis of eyes (patients operated in the setting of a tertiary eye care hospital between 2014 and 2020) requiring early enhancement (within one year of primary surgery) was conducted. Stability of refractive error, corneal tomography, and anterior segment Optical Coherence Tomography (AS-OCT) for epithelial thickness was performed. The correction post regression was done using photorefractive keratectomy and flap lift in eyes, wherein the primary procedure was SMILE and LASIK, respectively. Pre- and post enhancement corrected and uncorrected distance visual acuity (CDVA and UDVA), mean refractive spherical equivalent (MRSE), and cylinder were analyzed. IBM SPSS statistical software. Results: In total, 6350 and 8176 eyes post SMILE and LASIK, respectively, were analyzed. Of these, 32 eyes of 26 patients (0.5%) post SMILE and 36 eyes of 32 patients (0.44%) post-LASIK required enhancement. Post enhancement (flap lift in LASIK, and PRK in SMILE group) UDVA was logMAR 0.02 ± 0.05 and 0.09 ± 0.16 (P = 0.009), respectively. There was no significant difference between the refractive sphere (P = 0.33) and MRSE (P = 0.09). In total, 62.5% of the eyes in the SMILE group and 80.5% in the LASIK group had a UDVA of 20/20 or better (P = 0.04). Conclusion: PRK post SMILE demonstrated comparable results to flap lift post LASIK and is a safe and effective approach for early enhancement post SMILE.
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Purpose: To explore the long?term visual quality of the same subjects after sub?Bowman keratomileusis (SBK) or femtosecond laser in situ keratomileusis (FS?LASIK). Methods: This prospective study included patients screened for corneal refractive surgery at the Refractive Surgery Center of our Hospital between November 2017 and March 2018. One eye underwent SBK, while the other eye underwent FS?LASIK. Total higher?order aberrations, coma aberrations, and clover aberrations were evaluated before and at 1 month and 3 years after the procedure. The visual satisfaction of both eyes was investigated, respectively. The participants completed a surgical satisfaction questionnaire. Results: Thirty?three patients were included. There were no significant differences in total higher?order aberrations, coma aberrations, and clover aberrations between the two procedures before and 1 month and 3 years after surgery (all P > 0.05), except for the total coma aberrations in FS?LASIK were significantly higher compared with the SBK group at 1 month after surgery [0.51 (0.18, 0.93) vs. 0.77 (0.40, 1.22), P = 0.019]. The surgical satisfaction questionnaire scores of the SBK group and the FS?LASIK group were 9.8 ± 0.8 and 9.8 ± 0.8, respectively, at 1 month, and 9.7 ± 0.9 and 9.7 ± 1.0, respectively, at 3 years (all P > 0.05). Conclusion: There were no differences in corneal aberrations and satisfaction between SBK and FS?LASIK procedures at 1 month and 3 years.
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Purpose: To determine the safety and efficacy of low?energy settings in small incision lenticule extraction (SMILE) for correcting myopia and myopic astigmatism. Methods: We included patients aged ?18 years with the myopia of ?0.5 to ?10 D and myopic astigmatism of ?0.5 to ?5 Dcyl in this retrospective case series performed at a private eye hospital in South India. All patients had preoperative best?corrected visual acuity of LogMar 0.0 ± 0, with stable refraction for 1 year and normal corneal topography. Ocular surface disease and other pathology cases were excluded. The repetition rate of the laser was 500 kHz, and the pulse energy was 110 nJ. The lenticule diameter was set at 6.5 mm, cap diameter was 7.20 mm, and intended cap thickness was 110–130 ?. The spot distance was 4.5 ?m. All patients were evaluated immediately postoperation and on postoperative days 1, 8, and 30. Results: Overall, 541 eyes were included. The mean patient age was 25.03 ± 4.1 years. The mean spherical error was ?3.76 ± 1.84 Ds. The mean cylinder was ?1.24 ± 0.91. The mean spherical equivalent of refraction was ?4.22 ±1.94 D. The logMAR on postoperative day 1 was 0.0 ± 0. The mean spherical equivalent at 1 month was 0.28 ± 1.06 D. There was no loss of Snellen’s lines after the procedure. The mean spherical equivalent of refraction to the target was 95% within ± 0.50 D. The postoperative astigmatism was within 0.5 Dycl. No intraoperative complications of SMILE including retained lenticule fragments, tears of incision, or improper dissection occurred. Conclusion: Low?energy settings in SMILE are safe and effective in correcting myopia and myopic astigmatism including high cylinders (>3 Dcyl).
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AIM: To observe the clinical outcomes of femtosecond laser-assisted cataract phacoemulsification combined with anterior vitrectomy in the treatment of pediatric cataracts.METHODS: Retrospective study. A total of 10 patients(17 eyes)diagnosed as pediatric cataract in Foshan Aier Eye Hospital from January 2021 to September 2022 were collected, including 5 males(9 eyes)and 5 females(8 eyes), with an age of 3～9(4.50±1.20)years old. All children underwent femtosecond laser assisted phacoemulsification combined with anterior vitrectomy. The visual acuity, intraocular pressure and pigment deposits of intraocular lens(IOL)surface, synechia and hyperplasia of posterior capsule lens at 1wk, 1 and 6mo postoperatively were observed during the 6mo follow-up.RESULTS: All surgical procedures were successful, and there was no serious complication intraoperatively or postoperatively. BCVA(LogMAR)was 0.63±0.18 preoperatively and 0.42±0.10, 0.32±0.09, and 0.22±0.08 at 1wk, 1 and 6mo postoperatively(all P<0.001). There was no difference in the comparison of intraocular pressure at different times of surgery(P=0.125). There was no statistically significant difference in the incidence of IOL surface pigment deposits, synechia, and posterior capsule lens hyperplasia at different times after surgery(P>0.05). The incidence of IOL surface pigment deposits at 1wk, 1 and 6mo after surgery was 3 eyes(18%), 1 eye(6%), and 1 eye(6%), respectively, the incidence of synechia was 0 eye, 1 eye(6%), 2 eyes(12%), and the incidence of posterior capsule lens hyperplasia was 0 eye, 0 eye, and 2 eyes(12%), respectively.CONCLUSION: Femtosecond laser-assisted cataract phacoemulsification combined with vitrectomy for the removal of the anterior vitreous can effectively prevent anterior capsular tear and the occurrence of posterior capsule opacification.
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AIM: To observe and compare the changes in retinal peripheral refraction and aberrations after femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)versus small incision lenticule extraction(SMILE)for myopia correction.METHODS: A total of 71 patients(71 eyes)with myopia who underwent FS-LASIK from October 2022 to April 2023 in our hospital were selected as the FS-LASIK group, and 80 patients(80 eyes)with myopia who underwent SMILE were selected as the SMILE group. All patients underwent corneal wavefront aberration measurement and multispectral refractive topography preoperatively and 3mo postoperatively, as well as refraction difference value(RDV)in the range of 0°～10°, 10°～20°, 20°～30°, 30°～40°, and 40°～53° in the annulus of the retina, which were recorded as RDV-(0°～10°), RDV-(10°～20°), RDV-(20°～30°), RDV-(30°～40°), and RDV-(40°～53°). The results of two groups of patients were compared.RESULTS: No significant differences were observed in RDV-(0°～10°), RDV-(10°～20°), RDV-(20°～30°), RDV-(30°～40°), RDV-(40°～53°)between the two groups at 3mo post-operation(all P>0.05). Furthermore, the RDV-(20°～30°), RDV-(30°～40°)and RDV-(40°～53°)of the two groups at 3mo postoperatively were all significantly lower than those preoperatively(all P<0.05). The changes in coma(horizontal)and spherical aberration(SA)at 3mo postoperatively were smaller in the SMILE group [0.106(0.056, 0.171)and 0.115(0.081, 0.182)μm] than in the FS-LASIK group [0.206(0.104, 0.355)and 0.197(0.128, 0.254)μm](Z=-4.170, -5.016, all P<0.05). A negative correlation was found between postoperative SA and postoperative RDV-(10°～53°)(rs=-0.205, -0.181, -0.226, -0.244, all P<0.05).CONCLUSION: Both FS-LASIK and SMILE reduced retinal hyperopic defocus in the peripapillary macular range of 20°～53° eccentricity, and the postoperative changes in coma(horizontal)and SA were smaller with SMILE than with FS-LASIK. There was a certain correlation between postoperative SA and postoperative retinal peripheral defocus.
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AIM:To observe the changes in corneal aberrations and the characteristics of visual quality after transepithelial photorefractive keratectomy(T-PRK)and femtosecond small incision lenticule extraction(SMILE)in the correction of low myopia.METHODS: Prospective cohort study. A total of 32 cases(32 eyes)with low myopia who underwent T-PRK surgery and 45 cases(45 eyes)of SMILE surgery at Weifang Eye Hospital from April 2021 to April 2022 were selected. The uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), spherical equivalent(SE), corneal higher-order aberrations(HOAs)and objective visual quality were compared between the two groups.RESULTS:All patients completed the surgery successfully without complications such as infection. At 3mo postoperatively, the safety index was 1.13±0.16 and 1.16±0.17(P=0.48)and the efficacy index was 1.10±0.20 and 1.15±0.18(P=0.27)in the T-PRK and SMILE groups, respectively. The percentage of UCVA(LogMAR)≤0 in the T-PRK and SMILE groups was 94% and 98%, respectively. The percentage of the residual SE within ±0.5D was 88% and 87% in the two groups, respectively. The HOAs and spherical aberration in both groups were significantly increased(P≤0.01), and the increase was not statistically significant between the two groups(P=0.31, 0.89). There was no significant change in horizontal coma, horizontal trefoil and vertical trefoil in both groups(P&#x003E;0.05). The vertical coma in SMILE group was significantly increased(P&#x003C;0.001), while there was no significant change in T-PRK group(P&#x003E;0.05), and the increase was significantly greater in SMILE group than in T-PRK group(P&#x003C;0.001). There was no significant difference in objective scattering index(OSI), modulation transfer function cut off frequency(MTFcut off), Strehl ratio(SR), visual acuity(VA)100%, VA20% and VA9% between the two groups(P&#x003E;0.05).CONCLUSION:Both T-PRK and SMILE showed good safety, efficacy, and visual quality in correcting low myopia, while SMILE induced more vertical coma than T-PRK.
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AIM: To investigate the short-term visual quality outcomes after femtosecond laser small incision lenticule extraction(SMILE)and evolution implantable collamer lens(EVO-ICL)implantation for the correction of moderate myopia.METHODS: Prospective control study. A total of 51 cases(51 eyes)with moderate myopia who underwent SMILE or EVO-ICL implantation surgery at Weifang Eye Hospital from April 2021 to February 2022 were selected. They were divided into SMILE group(30 patients, 30 eyes)and EVO-ICL group(21 patients, 21 eyes)according to the surgical methods. The changes of visual acuity [uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA)], diopter [spherical equivalent(SE)] and related parameters of optical quality analysis system(OQAS Ⅱ)were observed before surgery and at 1wk, 1 and 3mo after surgery, and the quality of vision(QoV)questionnaire was completed.RESULTS: At 3mo after surgery, the safety index(postoperative CDVA/preoperative CDVA)of SMILE gruop and EVO-ICL group were 1.20(1.00, 1.20)and 1.20(1.00, 1.38), respectively, the efficacy index(postoperative UDVA/preoperative CDVA)were 1.00(1.00, 1.20)and 1.00(1.00, 1.20), respectively, and the percentage of SE within ±0.50D was 87% and 100%, respectively. In SMILE group, the objective scattering index(OSI)was increased after surgery, while modulation transfer function cutoff frequency(MTF cutoff), contrast visual acuity(VA)100%, and VA20% at 1wk and 1mo after surgery, and Strehl ratio(SR)and VA9% at each time point after surgery were all decreased compared with those before surgery(all P&#x003C;0.05). The OSI, MTF cutoff, SR and VA of EVO-ICL group showed no difference at each time point after surgery compared with those before surgery(all P&#x003E;0.05). The most common visual symptoms after SMILE and EVO-ICL implantation were visual haze and halos, respectively.CONCLUSION: Both SMILE and EVO-ICL implantation have good safety, efficacy and predictability in the short term after the correction of moderate myopia. Both groups had visual symptoms after surgery, but the overall satisfaction of patients was high. Furthermore, EVO-ICL implantation has better objective visual quality performance.
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AIM: To measure the indexes including postoperative distance, middle, near visual acuity and near stereopsis vision of patients with high myopia cataract and corneal astigmatism by femtosecond laser, which can quantify the diameter of capsulorhexis opening, and to evaluate the availability and necessity of Toric intraocular lenses(IOL)in high myopia.METHODS: Prospective case-control study. Patients with binocular high myopia cataract and corneal astigmatism who undergone femtosecond laser-assisted cataract surgery in our hospital were selected, and they were divided into two groups, with 20 cases(40 eyes)in group A(Toric IOL)and 20 cases(40 eyes)in group B(IQ IOL). Indexes, including preoperative corneal astigmatism and spherical equivalent and best-corrected distance visual acuity, uncorrected middle visual acuity, uncorrected near visual acuity, residual refractive astigmatism, near stereopsis acuity, total high-order aberration and total spherical aberration, were measured postoperatively at 7d, 1 and 3mo.RESULTS: The uncorrected middle and near visual acuity, Titmus near stereopsis acuity and residual astigmatism at 7d, 1 and 3mo after surgery were significantly improved in the Toric IOL group than the non-Toric group(all P&#x003C;0.05). The dependence on glasses was reduced. The postoperative best-corrected distance visual acuity, total high-order aberration and total spherical aberration of the two groups showed no statistically significant differences(all P&#x003E;0.05).CONCLUSIONS: The implantation of Toric IOL in patients with high myopia cataract and corneal astigmatism can effectively correct corneal astigmatism, improve postoperative uncorrected middle and near visual acuity and near stereopsis visual function, reduce postoperative dependence on glasses and enhance binocular stereopsis visual function.
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AIM: To evaluate the clinical efficacy of femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation.METHODS:The retrospective study enrolled 22 cases(26 eyes)of cataract patients who underwent femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation from August 2020 to August 2021. Follow-up to 3mo after surgery, the changes of far, intermediate and near visual acuity, aberration, Strehl ratio(SR)and modulation transfer function cutoff(MTF-cutoff)frequency were compared. Defocus curve at 1mo postoperatively was made, and the visual quality and satisfaction were evaluated after 3mo of surgery.RESULTS: The visual acuity of all patients was better than 0.1(LogMAR)at the far, intermediate and near distance at 1d, 1wk, 1 and 3mo postoperatively, and it was significantly improved compared with those before surgery(all P&#x003C;0.01). The defocus curve transitioned smoothly between +0.5 and -3.0D at 1mo after surgery, and visual acuity was better than 0.63. The total aberration and spherical aberration in the whole eye were significantly lower after surgery than before, and the SR and MTF-cutoff were significantly improved at 1d and 1wk after surgery(all P&#x003C;0.05). With high satisfaction and good visual quality, patients could watch at far, intermediate and near distance without wearing glasses at 3mo after surgery.CONCLUSION: Femtosecond laser-assisted cataract surgery combined with PanOptix trifocal intraocular lens implantation gave patients a comfortable and satisfactory full-course vision.
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AIM: To analyze the effect of full-femtosecond small incision lenticule extraction(SMILE)on the treatment of high myopia based on propensity score matching.METHODS: A total of 48 cases(48 eyes)of high myopia patients who underwent SMILE surgery in our hospital from May 2019 to May 2021 were selected as the observation group, and 48 cases(48 eyes)of high myopia patients who underwent FS-LASIK surgery were matched using propensity score matching as the control group. Follow up for 6mo after surgery, the changes in cylindrical, central corneal thickness, uncorrected visual acuity(UCVA), corneal endothelial cell related indicators [percentage of hexagonal endothelial cells(6A), coefficient of variation(CV)of endothelial cell area, central corneal endothelial cell density(ECD)] and corneal biomechanical indicators [simulated Goldman intraocular pressure(IOPg), corneal hysteresis(CH), corneal resistance factor(CRF), corneal compensated intraocular pressure(IOPcc)] between the two groups were compared, and the incidence of complications in both groups of patients was recorded.RESULTS: Both groups of patients showed significant improvements in cylindrical and UCVA at 3 and 6mo after surgery, as well as decreased central corneal thickness, corneal endothelial cells, and corneal biomechanics related indicators. The changes in the observation group were more significant(all P<0.05). During the follow-up period, there was no significant difference in the incidence of complications between the observation group and the control group(8% vs. 17%, P>0.05).CONCLUSION: SMILE has a definite effect on patients with high myopia and is helpful to improve visual acuity.
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AIM: To investigate the characteristics of changes in corneal epithelial thickness at the early postoperative stage of femtosecond assisted laser in situ keratomileusis(FS-LASIK)and its related influencing factors.METHOD: Retrospective study. A total of 120 patients(240 eyes)of myopia undergoing FS-LASIK from May 2021 to June 2022 were selected. The corneal epithelium thickness in the central area, inner ring area, and outer ring area of patients before and at 1d, 1wk, 1 and 3mo after operation was recorded. The relationship between the variation of corneal epithelium thickness and spherical equivalent, optical zone diameter, depth of cut and cutting ratio was analyzed by Pearson correlation.RESULTS: There was no statistical significance in corneal epithelial thickness in the central area, inner ring area and outer ring area at 1d after FS-LASIK compared with that before operation(P>0.05). At 1wk, 1 and 3mo after surgery, the corneal epithelial thickness in the central area, inner ring area and outer ring area increased compared with that before surgery, and the corneal epithelial thickness in the central area and inner ring area at 1 and 3mo after surgery was greater than that in the outer ring area(all P<0.05). The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thicker than that of low and moderate myopia patients before operation. The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thinner than that of low and moderate myopia patients at 1wk after operation(P<0.05). At 1 and 3mo after operation, the corneal epithelial thickness in the central, inner and outer ring areas of patients with high myopia was greater than that of patients with low and moderate myopia, and the changes of corneal epithelial thickness in the central, inner and outer ring areas were greater than those of patients with low and moderate myopia(P<0.05). The results of Pearson correlation showed that the changes in corneal epithelial thickness in the central and inner ring area were positively correlated with the corneal curvature, depth of cut and cutting ratio at 3mo after surgery, and they were in negative correlation with the age, spherical equivalent and optical zone diameter(P<0.05).CONCLUSION: The corneal epithelial thickness of patients thickened after the FS-LASIK operation, and it was correlated with age, corneal curvature, preoperative depth of cut, cutting ratio, spherical equivalent and the optic zone diameter.
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Femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)and small incision lenticule extraction(SMILE)are the mainstream corneal refractive surgeries at present. Despite efficacy, safety and predictability they have showed in refractive error correction, there are still complications relating to femtosecond laser, such as suction loss and opaque bubble layer(OBL), due to that the production of corneal flap or lenticule is dependent on the femtosecond laser. OBL is a complication that is unique to femtosecond laser surgery and the bubbles are generated from photo-disruptive effect towards corneal tissues which consisted of water vapor and carbon dioxide, and OBL gradually formed when the bubbles are trapped in the stroma. The bubbles can influence the intraoperative manipulation and postoperative visual quality. This review discusses the mechanism, grading, classification, and influencing factors of OBL and its effects on intraoperative manipulations and postoperative recovery, in the hope of providing reference and basis for further clinical studies.
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AIM:To evaluate the changes in corneal biomechanics of patients with moderate refractive error after receiving small-incision lenticule extraction(SMILE)and femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK)using the corneal visualization Scheimpflug technology(Corvis ST).METHODS:Prospective cohort study. A total of 65 moderate myopia patients(65 eyes)who were scheduled to undergo refractive surgery at the Ophthalmic Refractive Surgery Center of the Ningxia Eye Hospital from November 2020 to November 2021 were included in the study, and there were 30 eyes in the SMILE group and 35 eyes in the FS-LASIK group. The changes in corneal biomechanical parameters, including integrated radius(IR), inverse concave radius(ICR), deformation amplitude ratio 2mm(DAR2), stiffness parameter at first applanation(SP-A1), ambrosio relational thickness(ARTh)and the central curvature radius at highest concavity(HC-Radius)were observed by Corvis ST between both groups preoperatively and 1 and 3mo postoperatively.RESULTS: There were no statistical significance in biomechanical parameters between two groups of patients 1 and 3mo postoperatively(P&#x003E;0.05). IR, ICR and DAR2 of each groups of patients 1 and 3mo postoperatively were significantly increased than those preoperatively, and SP-A1, ARTh and HC-Radius were significantly decreased than those preoperatively(all P&#x003C;0.05). The biomechanical parameters at 1mo and 3mo postoperatively showed no statistical significance(P&#x003E;0.05). In addition, a positive correlation was found between central corneal thickness(CCT)and ARTh and SP-A1 of the two groups of patients at 3mo postoperatively(FS-LASIK group: r=0.727, 0.819, SMLIE group: r=0.683, 0.434, all P&#x003C;0.05), while a negative correlation was found between CCT and IR and ICR at 3mo postoperatively.(FS-LASIK group: r=-0.697, -0.622, SMLIE group: r=-0.447, -0.491, all P&#x003C;0.05).CONCLUSION:For patients with moderate myopia, both SMILE and FS-LASIK can reduce corneal biomechanical stability. Both surgeries showed no significant differences in the effect on biomechanical, and the biomechanical has been stabilized at 1mo postoperatively. A correlation was found between postoperative CCT and ARTh, SP-A1, IR and ICR.
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Objective:To investigate the risk factors of high intraocular pressure (IOP) after femtosecond laser in situ keratomileusis (FS-LASIK) in patients with high myopia, and construct and verify nomogram model.Methods:A retrospective clinical study. From January 2019 to January 2021, 327 patients (654 eyes) with high myopia treated with FS-LASIK in the Department of Ophthalmology of the 910th Hospital of the People's Liberation Army Coalition Security Force were included in the study. The patients were categorized into high IOP group and non-high IOP group according to whether high IOP occurred after surgery, which were 60 cases and 120 eyes (18.35%, 60/327) and 267 cases and 534 eyes (81.65%, 267/327), respectively. The clinical data of patients in the two groups were analyzed and observed, and the indicators with differences were subjected to one-way and multifactorial logistic regression analyses, and the results of the regression analyses were visualized to obtain the column line graphs using R3.5.3 software, and the accuracy of the column line graphs was verified by the consistency index (C-index), the calibration curves, and the subject's work characteristic curves (ROC curves).Results:Comparison of the number of cases of affected corneal thickness ( χ2=7.424), corneal curvature ( χ2=9.849), glucocorticoid treatment ( χ2=7.222), intraoperative IOP fluctuation ( χ2=11.475), corneal hysteresis ( χ2=6.368), and the incidence of intraoperative complications ( χ2=6.673) in the hypertensive IOP group and the nonvisualized IOP group were statistically significant ( P<0.05). Binary logistic regression analysis showed that corneal thickness >450 μm, corneal curvature≤38 D, glucocorticoid treatment, intraoperative IOP fluctuation, corneal hysteresis ≤8.0 mm Hg (1 mm Hg=0.133 kPa), and intraoperative complications were the risk factors for the occurrence of high IOP after FS-LASIK surgery in patients with high myopia ( P<0.05). The C-index of the column-line graph prediction model based on this was 0.722 (95% confidence interval 0.684-0.760), the calibration curve and the ideal curve were basically the same, and the area under the ROC curve was 0.709. Conclusions:Corneal thickness> 450 μm, keratometric curvature ≤38 D, glucocorticoid treatment, intraoperative fluctuation of intraocular pressure, and corneal hysteresis ≤8.0 mm Hg are the risk factors for the development of hyperopic IOP in highly risk factors for the development of high IOP after FS-LASIK surgery in myopic patients. The column-line diagram model constructed on the basis of the risk factors hava good accuracy.