Comparison of corneal refractive power and visual quality after LASEK, TransPRK or FS-LASIK / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the corneal refractive power and visual quality after three kinds of corneal refractive surgery: laser subepithelial keratomileusis(LASEK), transepithelial photorefractive keratectomy(TransPRK)and femtosecond laser assisted in situ keratomileusis(FS-LASIK).METHODS: Retrospective study. A total of 232 patients(464 eyes)who underwent elective corneal refractive surgery in our hospital from January 2021 to December 2022 were selected as the study subjects. They were divided into the LASEK group of 70 cases(140 eyes), TransPRK group of 76 cases(152 eyes), and FS-LASIK group of 86 cases(172 eyes)according to the different surgical choices made by the patients. Uncorrected visual acuity(UCVA), visual quality, biomechanical stability, tear film break-up time(BUT), Schirmer Ⅰ test(SⅠt)and quality of life were compared among the three groups at 1 and 3 mo postoperatively.RESULTS: The UCVA of the three groups significantly improved at 1 and 3 mo postoperatively, the total high-order aberrations, spherical aberration, horizontal coma, and vertical coma of the entire cornea were significantly increased, while the biomechanical stability in all three groups were significantly reduced(all P<0.05). At 3 mo postoperatively, the biomechanical stability in the TransPRK and LASEK groups were higher than those of the FS-LASIK group(all P<0.05), and the TransPRK group had higher quality of life scores than the LASEK group and FS-LASIK group(P<0.05). Furthermore, there was no significant difference in preoperative or postoperative BUT and SⅠt among the three groups(all P>0.05).CONCLUSION:In the treatment of ametropia, LASEK, TransPRK and FS-LASIK all have certain effects, and have similar results in improving UCVA and increasing visual quality. However, TransPRK and LASEK have more stable biomechanical properties than FS-LASIK, and have better efficacy in improving patients' quality of life.

Corrective effect of femtosecond laser assisted laser in situ keratomileusis Xtra on patients with moderate to high myopia after 2a postoperatively / 国际眼科杂志(Guoji Yanke Zazhi)

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.

Changes of corneal densitometry after small incision lenticule extraction and femtosecond laser in situ keratomileusis / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To compare the changes in corneal densitometry after small incision lenticule extraction(SMILE)and femtosecond laser in situ keratomileusis(FS-LASIK)and investigate the effect of corneal interface haze on vision after SMILE.METHODS: Prospective cohort study. A total of 93 patients(186 eyes)who were scheduled to undergo refractive surgery at the Ophthalmic Refractive Surgery Center of the Affiliated Hospital of Nantong University from May 2020 to October 2021 were included in the study, and there were 48 patients(96 eyes)in the SMILE group and 45 patients(90 eyes)in the FS-LASIK group. The changes in corneal densitometry, spherical equivalent(SE), and uncorrected visual acuity(UCVA)were observed and compared between the two groups before and at 1d, 1wk, 1, 3 and 6mo after surgery.RESULTS: The 93 patients all successfully completed the surgery, and there were no related complications during and after the surgery, and there were no lost cases. The UCVA of FS-LASIK group was 0.044±0.064 and -0.001±0.065 respectively at 1d and 1wk after surgery, which was better than that of SMILE group(0.102±0.077 and 0.023±0.064; all P<0.05). There was no statistical difference in the SE between the two groups at the postoperative follow-ups(P>0.05). The corneal densitometry values at 0-2 and 2-6 mm from corneal vertex and total corneal densitometry at 1d postoperatively in the FS-LASIK group were 18.0(17.5, 18.6), 16.2(15.6, 16.7)and 16.7(16.1, 17.3), which were lower than those of SMILE group [18.6(18.1, 19.3), 16.8(16.4, 17.4), 17.2(16.6, 17.8)](all P<0.05); The corneal densitometry values at 0-2 and 2-6 mm from corneal vertex and total corneal densitometry at 1wk postoperatively in the FS-LASIK group were 17.2(16.7, 17.6), 15.5(15.0, 15.9)and 15.9(15.3, 16.7), which were lower than those of SMILE group [17.6(17.1, 18.3), 16.0(15.6, 16.5), 16.6(15.9, 17.1)](all P<0.05).CONCLUSIONS: The transient interface haze after SMILE is responsible for the early higher corneal densitometry than FS-LASIK. The presence of interface haze is probably a factor for the quality of vision.

Changes in corneal biomechanics after small incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis evaluated by corneal visualization Scheimpflug technology / 国际眼科杂志(Guoji Yanke Zazhi)

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>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<0.05). The biomechanical parameters at 1mo and 3mo postoperatively showed no statistical significance(P>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<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<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.

Research progress of opaque bubble layer created in corneal stroma during femtosecond laser surgery / 国际眼科杂志(Guoji Yanke Zazhi)

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.

Changes in retinal peripheral refractive status and aberrations before and after femtosecond laser-assisted laser in situ keratomileusis and small incision lenticule extraction / 国际眼科杂志(Guoji Yanke Zazhi)

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.

Observation of corneal wavefront-guided FS-LASIK in the treatment of myopia with different degrees of astigmatism / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To compare the postoperative efficacy of corneal wavefront-guided femtosecond laser-assisted excimer in situ keratomileusis(FS-LASIK)in the treatment of myopia patients with different degrees of astigmatism and the changes of corneal higher order aberration.METHODS: A total of 133 patients(265 eyes)with myopia and astigmatism were enrolled in this retrospective study. All of them underwent corneal wavefront-guided FS-LASIK surgery for the first time in Aier Eye Hospital(Kunming)from April to October 2020. The patients were divided into three groups according to the different astigmatism: Low astigmatism group: astigmatism ≤1.0D, 62 cases(124 eyes), medium astigmatism group: a total of 54 cases(107 eyes)with astigmatism was 1.25-2.0D, high astigmatism group: a total of 17 cases(34 eyes)with astigmatism ≥2.25D. Visual acuity and refraction were recorded before surgery and 3mo after the surgery and the cornea of the patients was measured by Pentacam three-dimensional corneal topography. Record total higher order aberrations(root mean square), spherical aberration, horizontal coma, vertical coma, horizontal clover and oblique clover in the 6mm diameter range of the cornea. The postoperative effects of the three groups of patients were observed and the changes of corneal high order aberration before and after surgery were compared. RESULTS: The validity index of visual acuity in the three groups of patients was all greater than 1.1 and the residual diopter was all within ±0.30D. The residual diopter in the low astigmatism group was the least than that of the other two groups(P<0.05). At 3mo after surgery, the corneal total higher order aberration, spherical aberration and vertical coma of the three groups were all increased compared with those before surgery(P<0.05). The spherical aberration increase in the high astigmatism group was less than that in the other two groups(P<0.05).CONCLUSION: Corneal wavefront-guided FS-LASIK surgery is safe and effective in the treatment of myopia with different degrees of astigmatism, and the effect is also accurate for patients with high astigmatism. The degree of of preoperative astigmatism is not responsible for increased corneal higher order aberration after the surgery.

Comparison of clinical effects of corneal topography-guided FS-LASIK and TICL implantation for myopia with moderate to high astigmatism / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To explore the clinical efficacy of the myopic with moderate to high astigmatism correction between corneal topography-guided femtosecond laser in situ keratomileusis(FS-LAISK)and Toric implantable collamer lens(TICL).METHODS: A total of 60 patients(115 eyes)with moderate to high astigmatism in myopia(115 eyes)from June 2019 to June 2021 and treated in the refractive center of Heyuan Aier Eye Hospital were enrolled in the study, then were divided into Group A and Group B according to the operations they would accept. There were 32 patients(62 eyes)in the Group A treated with corneal topography-guided FS-LASIK and 28 patients(53 eyes)in the Group B treated with TICL implantation. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), spherical diopter and residual astigmatism were recorded preoperatively and postoperatively at 3mo, surgical safety and efficacy were evaluated, and the Alpins vector analysis was used to evaluate the astigmatism.RESULTS: The postoperative at 3mo, there were no differences in the safety index(1.163±0.167 vs 1.136±0.194)and the efficacy index(1.145±0.159 vs 1.123±0.196)between the patients of the two groups(P>0.05). However, the astigmatism vector analysis showed that there were statistically differences in the index of success index [0.125(0.091, 0.200)vs 0.200(0.167, 0.250)], the correction index [1.000(0.902, 1.066)vs 0.834(0.783, 0.869)] and the flattening index [1.000(0.922, 1.079)vs 0.835(0.795, 0.870)](P<0.01).CONCLUSION:Corneal topography-guided FS-LASIK and TICL implantation were effective and safe in correcting myopia with moderate to high astigmatism, and corneal topography-guided FS-LASIK perform better than TICL implantation for the astigmatism correction.

Meta-analysis of clinical efficacy after FS-LASIK and ICL implantation / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To compare the clinical effects of FS-LASIK and ICL implantation.<p>METHODS: From January 2015 to January 2020, used computer to search the clinical contrast test of FS-LASIK and ICL implantation published in CNKI database, Wanfang database, Chongqing VIP Chinese Sci tech journal full-text database, China Bioligy Medicine disc(CBMdisc), Cochrane Library, PubMed, MEDLINE and other databases,using rev-man5.3 statistical software for Meta-analysis and statistical processing.<p>RESULTS: Totally 11 studies were brought into the analysis, including 673 patients and 1 301 operative eyes. The results of Meta-analysis showed that there was no statistical significance in the safety, objective visual quality, spherical equivalent degree, cylinder, diopter of correction, trefoil aberration and coma aberration of FS-LASIK and ICL implantation after operation, but there was statistical significance in the effectiveness, total higher-order aberration, spherical aberration and contrast sensitivity of FS-LASIK and ICL implantation after operation.<p>CONCLUSION: Compared with ICL implantation, the total high-order aberrations and spherical aberrations of FS-LASIK are larger, and the contrast sensitivity is lower. The ICL implantation has more clinical-effect superioity than FS-LASIK, meanwhile it has reversibility and less complications.

Comprehensive comparison of early visual quality with two corneal refractive surgeries between SMILE and FS-LASIK in patients with high myopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the changes of early visual quality of patients with high myopia after small incision lenticule extraction(SMILE)and femtosecond assisted laser in situ keratomileusis(FS-LASIK)by the double-pass optical quality analysis system Ⅱ(OQAS Ⅱ)and Pentacam corneal topography.<p>METHODS: A prospective non-randomized controlled study was conducted among 148 eyes of 74 patients with high myopia. These patients were treated by the same surgeon in our hospital from March 2020 to September 2020. According to their wishes, 86 eyes with 43 patients were treated with SMILE and 62 eyes with 31 patients were treated with FS-LASIK. The uncorrected visual acuity(UCVA), modulation transfer function cut off frequency(MTF cut off), Strehl ratio(SR), objective scattering index(OSI), predicted visual acuity values(VA 100%, VA 20%, VA 9%), high-order aberration(HOA), horizontal aberration(<i>Z 13</i>), vertical coma(<i>Z -13</i>)and spherical aberration(<i>Z 04</i>)preoperatively, 1 and 7d postoperatively were collected and analyzed.<p>RESULTS:There was no statistical significance in preoperative age, spherical equivalent(SE), UCVA, MTF cut off, SR, OSI, VA 100%, VA 20%, VA 9%, HOA, <i>Z 13</i>, <i>Z -13</i> and <i>Z 04</i>(<i>P</i>>0.05). The OSI of the SMILE group was higher than the FS-LASIK group at postoperative 1d(2.3±2.1 <i>vs</i> 1.8±1.1). The difference in OSI between the two groups was not statistically significant at postoperative 7d(1.2±0.7 <i>vs</i> 1.3±0.7). The HOA and <i>Z04</i> in the FS-LASIK group were higher than the SMILE group at postoperative 1d and 7d(<i>P</i><0.001). The UCVA, <i>Z 13</i>, <i>Z -13</i>, MTF cut off, SR, VA 100%, VA 20%, and VA 9% between the two groups were no statistical significance at postoperative 1d and 7d(<i>P</i>>0.05).<p>CONCLUSION:FS-LASIK is easier to introduce corneal high-order aberration and spherical aberration in the early postoperative period, while SMILE with 2mm incision only introduces higher scatter at postoperative 1d. Therefore, SMILE can obtain better visual quality than FS-LASIK in the early postoperative period among patients with high myopia after corneal refractive surgery.