[Comparison of corneal power assessment methods after small incision lenticule extraction].

Objective: To compare the accuracy of different corneal curvature parameters in assessing the corneal refractive status and tracking corneal power changes after small incision lenticule extraction (SMILE). Methods: This prospective cross-sectional study tracked and recorded total corneal curvature parameters measured by different instruments before and three months after SMILE for myopia. These parameters, including total keratometry (TK) from the IOLMaster 700, total corneal refractive power (TCRP) from the Pentacam AXL, real keratometry (RK) from the CASIA 2, and corrected parameters calculated using the Haigis, Shammas, and Maloney methods, were compared with data obtained using the clinical history method (CHM). Surgically induced changes in TK, TCRP, and RK were analyzed and compared with those in spherical equivalent on the corneal plane (ΔSEco). Results: The study included 40 eyes (40 participants). After SMILE, the difference was smallest between TK [(0.08±0.38) D] and CHM values (P>0.05). However, TCRP, RK, KHaigis, KShammas, and KMaloney were significantly different from CHM data (P<0.05). The width of the 95% limits of agreement of TK (1.49 D) was narrowest, followed by that of RK (1.57 D). Pearson analysis showed that each parameter had a good correlation with CHM data. The differences between the changes in TK, TCRP and RK caused by surgery and ΔSEco were (0.03±0.39) D, (0.17±0.43) D, and (-0.19±0.46) D, respectively. The width of the 95% limits of agreement of ΔTK (1.54 D) was narrowest, and the correlation coefficient of ΔTK (0.951) was highest. Conclusion: The parameter TK of the IOLMaster 700 can provide accurate and objective corneal power evaluation after SMILE.

[Assessment of corneal biomechanical changes after small incision lenticule extraction with Pentacam and Corvis ST].

Objective: To investigate the application value of Pentacam combined with Corvis ST in evaluation of the changes of corneal biomechanics after femtosecond laser small incision lenticule extraction (SMILE) in Chinese myopia with an irregular cornea. Methods: The clinical records for 104 eyes of 57 patients who received SMILE in the Refractive Center of Beijing Tongren Hospital during January 2018 and May 2018 were collected. According to the keratoconus severity index (KSI), they were divided into two groups: regular corneal group (KSI<15%) and irregular corneal group (KSI: 15% to 25%). In both groups, the anterior corneal surface radius curvature was>7.25 mm (K<46.50 diopters), the posterior corneal surface radius curvature was>5.90 mm, the thinnest pachymetry was>490 µm, and best corrected visual acuity was ≥1.0. The vision, refraction, and corneal biomechanics before and after SMILE were assessed. The Topographic and Biomechanics Index (TBI) was analyzed by Pentacam combined with Corvis ST. Results: Before SMILE, the Corvis Biomechanical Index (CBI), TBI, and Belin/Ambrósio Deviation Normalized Index (BADD) of the irregular corneal group were significantly higher (t=-2.17, -6.78, -4.37, P<0.05) than the regular corneal group, while the stiffness parameter (SPA1) was significantly lower (t=2.58, P=0.011) compared to the regular corneal group (P<0.05). In the irregular group, the TBI was (0.28±0.2); the maximum value was 0.03, and the minimum value was 0.43. The CBI was (0.09±0.21); the maximum value was 0.00, and the minimum value was 0.54. The BADD was (1.33±0.47); the maximum value was 0.42, and the minimum value was 2.26. In the regular group, the TBI was (0.05±0.08); the maximum value was 0.00, and the minimum value was 0.20. The CBI was (0.01±0.03); the maximum value was 0.00, and the minimum value was 0.17. The BADD was (0.92±0.46); the maximum value was 0.00, and the minimum value was 1.64. There was no significant difference between two groups in age (t=0.20, P=0.508), central corneal thickness (t=1.64, P=0.104), biomechanical corrected IOP (t=0.73, P=0.468), max inverse radius (t=-0.24, P=0.815), spherical equivalent (t=-0.97, P=0.335), and best corrected visual acuity (t=0.21, P=0.833). After SMILE, the deformation amplitude in the irregular group was significantly higher at 1 month and 3 months (t=-3.13, -3.09, P<0.05). The irregular group had a significantly higher deformation amplitude ratio at 1 week, 1 month, and 1 year (t=-2.72, -3.39, -2.51, P<0.05). The SPA1 in the irregular group was significantly lower than the regular group at 1 week, 1 month, and 3 months (t=2.11, 2.73, 3.70, P=0.335, 0.010,<0.001). The changes of deformation amplitude (t=0.50, -1.10, -0.73, 2.12, P>0.05), max inverse radius (t=-1.52, -1.41, 0.01, -0.79, P>0.05), and SPA1(t=0.89, 0.90, 1.12, 0.90, P>0.05) after SMILE were similar between the irregular and regular groups, except that at 1 month after SIMILE, the deformation amplitude ratio changed more significantly in the irregular group (t=-3.01, P=0.003). Conclusions: The changes of corneal biomechanics in the groups of regular cornea and irregular cornea were stable with no significant difference during 1 year of post-SMILE. The diagnosis based on the corneal topography and corneal biomechanics is of certain significance for the screening of early keratoconus before keratorefractive surgery. (Chin J Ophthalmol, 2020, 56:103-109).

[Comparison of the visual quality at 1 year following femtosecond laser-assisted LASIK, wavefront-guided femtosecond LASIK and small incision lenticule extraction for myopia and astigmatism].

Objective: To investigate mesopic contrast sensitivity (CS) and high-order aberrations after femtosecond laser-assisted LASIK (FS-LASIK), wavefront-guided femtosecond LASIK (WF-LASIK) and small incision lenticule extraction (SMILE) for myopia and astigmatism. Methods: In this case-control study, 212 eyes of 108 patients with myopia and astigmatism from September 2014 to September 2016 were treated by refractive surgery. There were 34 males (66 eyes) and 74 females (146 = eyes), aged 27 (24, 32) years. They were divided into 3 groups, with 37 patients (71 eyes), 35 patients (69 eyes) and 36 patients (72 eyes) treated by FS-LASIK, WF-LASIK and SMILE, respectively. Refraction diopters, corneal tomography, wavefront aberrations and contrast sensitivity were evaluated before and at 12 months after surgery. The results of different groups were compared by rank sum test. Results: At 12 = months of follow-up, 69 eyes (97.18%) treated by FS-LASIK, 67 eyes (97.10%) by WF-LASIK and 69 eyes (95.83%) by SMILE had the uncorrected distance visual acuity of 20/20 or better. Fifty-nine eyes (83.10%) treated by FS-LASIK, 60 eyes (86.96%) by WF-LASIK and 61 eyes (84.72%) by SMILE had better postoperative uncorrected distance visual acuity than preoperative corrected distance visual acuity. Surface regularity index of the WF-LASIK group decreased from 0.11 (0.07, 0.28) to 0.07 (0.06, 0.20) (Z=-2.662, P=0.008), which was less than that of the FS-LASIK and SMILE groups (Z=-3.236, -3.118, P=0.001, 0.000). Surface asymmetry index of the WF-LASIK group increased from 0.34 (0.25, 0.43) to 0.38 (0.30, 0.52) (Z=-2.140, P=0.032), which was less than that of the FS-LASIK and SMILE groups (Z=-2.910, -3.779, P=0.004, 0.000). The root mean square of high-order of the FS-LASIK group increased from 0.32 (0.27, 0.41) to 0.53 (0.40, 0.65) (Z=-6.228, P=0.000), which was more than that of the WF-LASIK and SMILE groups (Z=-3.595, -4.806, P=0.000, 0.000). Coma of the WF-LASIK group increased from 0.16 (0.11, 0.24) to 0.26 (0.15, 0.37) (Z=-3.816, P=0.000), which was less than that of the FS-LASIK group (Z=-3.528, P=0.000). Spherical aberration of the FS-LASIK and WF-LASIK groups increased from 0.10 (0.05, 0.21) and 0.08 (0.04, 0.12) to 0.24 (0.13, 0.34) and 0.15 (0.09, 0.26), respectively (Z=-5.141, -4.864, P=0.000, 0.000), which were more than that of the SMILE group (Z=-2.549, -4.682, P=0.011, 0.000). CS of the WF-LASIK group at 12 cycles per degree (c/d) increased from 1.34 (1.18, 1.48) to 1.48 (1.34, 1.63) (Z=-2.985, P=0.003), which was more than that of the FS-LASIK and SMILE groups (Z=-3.194, -2.977, P=0.001, 0.003). CS with glare of the WF-LASIK group at 12.0 c/d increased from 1.26 (1.18, 1.34) to 1.34 (1.34, 1.63) (Z=-3.608, P=0.000), which was more than that of the FS-LASIK and SMILE groups (Z=-4.033, -2.913, P=0.000, 0.004). Conclusions: FS-LASIK, WF-LASIK and SMILE achieved ideal visual outcomes at 12 months postoperatively. WF-LASIK treated eyes showed the best corneal symmetry, the least increase of high-order aberrations and the best visual quality among three kinds of surgeries. (Chin J Ophthalmol, 2020, 56: 118-125).

Preoperative computed tomography-guided hook-wire positioning of pulmonary nodules.

This study aimed to analyze the clinical application value of computed tomography (CT)-guided hook-wire positioning before thoracoscopic surgery. Eighty-four patients who had received a thoracoscopic wedge resection of pulmonary nodules between January and December 2013 were selected. Group A consisted of 38 cases where the hook-wire positioning technique was not used, and the positioning approaches were intraoperative observation and palpation. Group B consisted of 46 cases where the hook-wire positioning technique was used. The diameter of each nodule was less than 2 cm, and all patients underwent the operation within 2 h of invasive positioning. The evaluation indexes included positioning success rate, positioning-related complications, and rate of conversion to thoracotomy. In Group A, nine patients (23.68%) underwent conversion to thoracotomy; in Group B, three patients (6.52%) did. This difference was statistically significant (P < 0.05). The average operation duration was 118 ± 21 min in Group A and 53 ± 18 min in Group B. The difference between both groups was statistically significant (P < 0.05). The average length of hospital stay of patients who underwent conversion to thoracotomy was 8.7 ± 2.2 days, and of patients who underwent thoracoscopic pulmonary wedge resection was 4.5 ± 1.6 days. This difference was statistically significant (P < 0.05). Therefore, CT-guided hook-wire positioning of pulmonary nodules before thoracoscopic surgery has clinical application value. It helps to accurately locate the pulmonary nodules, effectively lowers the rate of conversion to thoracotomy, and reduces the operation duration.