ABSTRACT
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.
ABSTRACT
@#AIM: To explore the effect of different energy parameters of femtosecond laser small incision lenticule extraction(SMILE)on stage Ⅰ opaque bubble layer(OBL)and visual quality. <p>METHODS: A retrospective analysis of the clinical data of 216 patients(432 eyes)who came to our hospital for SMILE surgery from July 2018 to December 2019. According to whether stage Ⅰ OBL occurred, they were divided into OBL group(42 eyes)and non-OBL group(390 eyes). The age, visual acuity parameters, corneal parameters, microlens parameters and energy parameters were compared between the two groups, and multivariate regression analysis was used to analyze the relationship between the difference in energy settings and the OBL of stage Ⅰ. The uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), and modulation transfer function cut-off spatial frequency(MTF<sub>cut-off</sub>), Strehl Ratio(SR)and Objective Scattering Index(OSI)with energy parameters of 130, 135, 140, 145, and 150 nJ before and 1mo after surgery were compared. The correlation between energy parameters and stage Ⅰ OBL, UCVA, BCVA, MTF<sub>cut-off</sub>, SR, OSI were analyzed. <p>RESULTS: Multivariate regression analysis showed that the energy setting with a difference of 5nJ did not show an association with stage Ⅰ OBL. In the different energy parameter groups, LogMAR UCVA, MTF<sub>cut-off</sub>, and OSI at 1mo after surgery were improved compared with preoperatively(<i>P</i><0.05), and the difference between the groups were statistically significant(<i>F</i>=75.712, 15.304, 26.293, all <i>P</i><0.05). SMILE intraoperative energy parameters were negatively correlated with UCVA(<i>r</i>=-0.272), MTF<sub>cut-off</sub>(<i>r</i>=-0.132), and OSI(<i>r</i>=-0.151)1mo after surgery(<i>P</i><0.05). <p>CONCLUSION: When using a 4.5μm dot pitch, in the usual energy range, the lower the energy, the better the postoperative visual quality, but it does not significantly affect the incidence of stage Ⅰ OBL during SMILE surgery.
ABSTRACT
@#AIM: To evaluate the effect of opaque bubble layer(OBL)on the ocular cylotorsion compensation during FS-LASIK procedures. <p>METHODS: Prospectively clinical study. From July 2019 to September 2019, two-hundred FS-LASIK patients(400 eyes)were randomly included into this study. The total OBL incidence, flap-out OBL incidence, flap-in OBL incidence, incidence of dynamic cyclotorsion component(DCC)and incidence of static cyclotorsion component(SCC)were statistically analyzed. <p>RESULTS: OBL developed in 183 eyes of 400 FS-LASIK eyes, with a total OBL incidence of 45.8%. DCC was successfully performed on 397 eyes, with a total DCC incidence of 99.2%. SCC was successfully performed on 293 eyes, with a total SCC incidence of 73.2%. Neither flap-out OBL nor flap-in OBL could disturb the successful implementation of DCC during the operation(<i>P</i>>0.05). Both flap-out OBL and flap-in OBL could impact the SCC implementation and make it fail(<i>P</i><0.05).<p>CONCLUSION: OBL can result in failure of SCC implementation during the FS-LASIK procedures.
ABSTRACT
AlM: To compare the impact of different thickness of corneal cap design on small incision lenticule extraction ( SMlLE) operation.METHODS: Forty-six cases of myopia patients ( 92 eyes) intends to SMlLE operation in our hospital were collected , and were randomly divided into 2 groups:corneal cap thickness design for 110μm in group A and 120μm in group B. Other operation parameters designs were consistent. All patients were surgeried by the same surgeon. The incidence of opaque bubble layer ( OBL ) , the ratio of difficult separation of lens, uncorrected visual acuity ( UCVA ) of each time points, and spherical equivalent ( SE) were compared.RESULTS: lntraoperative OBL incidence rate of 110μm group was higher than that of 120μm group with significant difference between the two group (P0. 05). SE were compared at 7d and 6mo after operation, showed no significant difference (P>0. 05)CONCLUSlON: Compared with 120μm group, corneal cap design SMlLE operation in 110μm group are more prone to OBL and difficult separation of lens, thus affects UCVA and postoperative recovery rate. There is no significant difference in long-term UCVA.