OBJECTIVES: To compare the efficacy of toric implantable collamer lens (Toric-ICL) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for myopia correction in patients with moderate to high myopia complicated with astigmatism. METHODS: We retrospectively collected data from 64 patients (aged 18-42 years) with moderate to high myopia complicated with astigmatism (128 eyes) undergoing either Toric-ICL (28 patients/56 eyes) or FS-LASIK (36 patients/72 eyes) at our department between January, 2019 and December, 2020. The changes of uncorrected distance visual acuity (UCVA), spherical equivalent (SE), mean astigmatism correction index (CI), corneal endothelial cell density (ECD) and intraocular pressure (IOP) following the procedures were compared between the two groups. RESULTS: In FS-LASIK group, all the eyes (72/72) achieved an UCVA≥1.0, similar to the rate in Toric-ICL group (55/56 eyes; P=0.2374). The postoperative SE was also comparable between FS-LASIK and Toric-ICL groups [0.43±0.06 D (range: -1.0 to 1.50 D) vs 0.38±0.05 D (range: -0.75 to 1.00 D); P=0.56]. The mean astigmatism CI was significantly higher in FS-LASIK group than in Toric-ICL group (0.8561 vs 0.7176; P<0.0001), and 88.89% of the eyes in FS-LASIK group and 69.64% in Toric-ICL group had postoperative astigmatism ≤0.50 D. No significant changes were observed in postoperative corneal ECD in FS-LASIK group, whereas ECD decreased significantly after the procedure in Toric-ICL group (P=0.0057). The patients undergoing Toric-ICL exhibited no significant changes of postoperative IOP, but the patients receiving FS-LASIK had significantly reduced IOP after the procedure (P<0.001). CONCLUSIONS Although the patients included in Toric-ICL group had higher myopia and astigmatism, Toric-ICL still showed better predictability and efficacy for astigmatic correction in Toric-ICL group. Toric-ICL is an effective and safe equivalent of FS-LASIK for correcting moderate myopia but can be more advantageous for correcting high myopia with astigmatism.
Humans ; Astigmatism/complications* ; Myopia/complications* ; Keratomileusis, Laser In Situ/methods* ; Retrospective Studies ; Adult ; Visual Acuity ; Adolescent ; Young Adult ; Treatment Outcome ; Male ; Lens Implantation, Intraocular/methods* ; Female ; Phakic Intraocular Lenses ; Intraocular Pressure

OBJECTIVES: To investigate angle Kappa and diopter distribution in myopic patients and the changes of angle Kappa and corneal morphology after Sub-Bowman-Keratomileusis (SBK), and to analyze the effects of the surgery on corneal morphologic changes and the patients' near fixation characteristics. METHODS: The clinical data of 134 myopic patients (268 eyes) undergoing SBK from August 2015 to August 2016 were retrospectively analyzed. Angle Kappa, corneal curvature in the central corneal region of 3 mm, and post-corneal Diff value were measured by Orbscan IIz Corneal Topography System before operation, 1 month and 6 months after operation. According to the values of angle Kappa before SBK, the patients were divided into 2 groups: the large K group (angle Kappa≥5°, 71 eyes) and the small K group (angle Kappa<5°, 197 eyes). Correlation analysis of the factors influencing angle Kappa at 6 months after operation was performed. RESULTS: In the large K group, angle Kappa was (5.67±0.65)°, spherical equivalent was (-4.84±2.32) D, and angle Kappa was decreased after operation (both CONCLUSIONS The angle Kappa is decreased in low-moderate myopia patients with large angle Kappa, while is increased in high myopia patients with small angle Kappa after SBK. Myopia patients after SBK will look for the new balance of the binocular accommodation and vergence function for improving the comfort in the near-work situations.
Cornea/surgery* ; Humans ; Keratomileusis, Laser In Situ ; Myopia/surgery* ; Refraction, Ocular ; Retrospective Studies

OBJECTIVE: To compare the different intraocular lens (IOL) calculation formulas available on the American Society of Cataract and Refractive Surgery (ASCRS) IOL power calculator website among Asian eyes with previous corneal refractive surgery. METHODS: A retrospective cohort study of 84 eyes in 68 Asian patients who had phacoemulsification with previous LASIK or photorefractive keratectomy (PRK) was done. Using the post-phacoemulsification manifest refraction spherical equivalent (MRSE) as target refraction, IOL prediction error (PE) for each formula was calculated as the implanted minus the predicted IOL power. Refractive PE was determined by calculating that 1 diopter (D) of IOL PE produces 0.7 D of refractive error at the spectacle plane. RESULTS: Comparing the Shammas, Haigis-L, Barrett True-K No History, ASCRS Average IOL Power No History, Barrett True-K, and ASCRS Average IOL Power with Change in Manifest Refraction (ΔMR), the mean IOL PEs ranged from -0.23 to -0.62 D, with the Barrett True-K having the lowest PE. The median refractive PEs for all formulas were similar at 0.35 D, except for the Haigis-L at 0.53 D. The ASCRS average with ΔMR had a statistically higher percentage of eyes within 0.5 D of target refraction versus other formulas (p<0.05). The Haigis-L IOL PE and refractive PE were significantly higher than the Barrett True-K (p<0.001), and the ASCRS average with ΔMR (p<0.001) respectively. The ASCRS average with ΔMR produced a significantly smaller variance of IOL PE (p<0.05). CONCLUSION: Accounting for PEs and variance, the ASCRS average IOL power with ΔMR is recommended, followed by the ASCRS average IOL power No History if without historical data.
Keratomileusis, Laser In Situ

The decrease of corneal stiffness is the key factor leading to keratoconus, and the corneal collagen fiber stiffness and fiber dispersion are closely related to the corneal biomechanical properties. In this paper, a finite element model of human cornea based on corneal microstructure, namely collagen fiber, was established before and after laser assisted in situ keratomileusis (LASIK). By simulating the Corvis ST process and comparing with the actual clinical results, the hyperelastic constitutive parameters and corneal collagen fiber stiffness modulus of the corneal material were determined before and after refractive surgery. After LASIK, the corneal collagen fiber stiffness modulus increased significantly, and was highly correlated with central corneal thickness (CCT). The predictive relationship between the corneal collagen fiber stiffness modulus and the corresponding CCT before and after surgery was: = exp(9.14 - 0.009CCT ), = exp(8.82 - 0.008CCT ). According to the results of this study, the central corneal thickness of the patient can be used to estimate the preoperative and postoperative collagen fiber stiffness modulus, and then a personalized corneal model that is more consistent with the actual situation of the patient can be established, providing a theoretical reference for more accurately predicting the safe surgical cutting amount of the cornea.
Biomechanical Phenomena ; Cornea ; Corneal Topography ; Finite Element Analysis ; Humans ; Keratomileusis, Laser In Situ ; Myopia

PURPOSE: To report a case of chemical injury of the cornea caused by high-dose ethanol during orbital wall fracture repair. CASE SUMMARY: A 56-year-old male presented with pain after blowout fracture repair surgery. During the surgery, 2% hexethanol solution (2% chlorhexidine and 72% ethanol mixture), which was used for disinfection of the face, flowed into the left eye. Conjunctival injection in the left limbus, a large corneal epithelial defect, and severe stromal edema were subsequently observed. The patient was treated with topical antibiotics, steroids, and autologous serum eye drops. After 1 week, the corneal epithelial defect was improved, but at the second month of therapy, recurrent corneal erosion with deterioration of the endothelial cell function occurred. Anterior stromal puncture and laser keratectomy were performed. The corneal epithelial defect and erosion improved, but the endothelial cell density was severely decreased. CONCLUSIONS: The 2% hexethanol solution is usually used for preoperative skin disinfection, but it contains a high concentration of ethanol. The surgeon should be aware that high concentrations of ethanol may result in severe corneal damage, including corneal endothelial dysfunction and limbal cell deficiency.
Anti-Bacterial Agents ; Chlorhexidine ; Cornea ; Corneal Injuries ; Corneal Surgery, Laser ; Disinfection ; Edema ; Endothelial Cells ; Ethanol ; Humans ; Male ; Middle Aged ; Ophthalmic Solutions ; Orbit ; Punctures ; Skin ; Steroids

PURPOSE: To evaluate laser in situ keratomileusis (LASIK) flap thickness predictability and morphology by femtosecond (FS) laser and microkeratome (MK) using anterior segment optical coherence tomography. METHODS: Fifty-two candidates for the LASIK procedure were stratified into two groups: FS laser-assisted (Allegretto FS-200) and MK flap creation (Moria 2). Flap thickness was determined at five points. The side-cut angle was measured in three directions at the margin interface. LASIK flap assessment was performed one month postoperatively by Spectralis anterior segment optical coherence tomography. RESULTS: Fifty-two patients (93 eyes) were recruited; 49 eyes were stratified to the FS group and 44 eyes to the MK group. The FS group had relatively even flap configurations, and the MK group had meniscus-shaped flaps. Mean differences between planned and actual flap thickness were 12.93 ± 8.89 and 19.91 ± 5.77 µm in the FS and MK groups, respectively. In thin flaps (100 to 110 µm), there was a significant disparity between the two groups (7.80 ± 4.71 and 19.44 ± 4.46 µm in the FS and MK groups, respectively). However, in thicker flaps (130 µm), comparable flap thickness disparity was achieved (18.54 ± 9.52 and 20.83 ± 5.99 µm in the FS and MK groups, respectively). Mean side-cut angle was 74.29 ± 5.79 degrees and 32.34 ± 4.94 degrees in the FS and MK groups, respectively. CONCLUSIONS: Comparable flap thickness predictability was achieved in thicker flaps (130 µm), while the FS laser technique yielded a more predictable result in thinner flaps (100 to 110 µm). Different flap morphology was observed in meniscus flaps in MK-LASIK and flap morphology in FS-LASIK.
Humans ; Keratomileusis, Laser In Situ ; Tomography, Optical Coherence

PURPOSE: To evaluate the efficacy of 3% diquafosol tetrasodium (DQ) after laser-assisted in-situ keratomileusis (LASIK). METHODS: This prospective randomized study included 150 eyes in 75 patients who were scheduled for LASIK. The patients in the 3% diquafosol tetrasodium (DQ) group (37 patients, 74 eyes) were instructed to apply one drop of DQ, six times daily post-op, while the patients in the 0.3% sodium hyaluronate (HA) group (38 patients, 76 eyes) were instructed to apply one drop of HA, six times daily post-op. A Schirmer test, tear film break-up time (BUT), corneal and conjunctival fluorescein staining score (FLSS), and ocular surface disease index (OSDI) were evaluated pre-op and at 1, 4, and 12 weeks post-op while the tear osmolarity was evaluated pre-op and at 4 and 12 weeks post-op. RESULTS: There was no significant difference between the two groups regarding Schirmer test results or tear osmolarity and conjunctival FLSS. The BUT was significantly higher in the DQ group at 1 week and 12 weeks post-op. The corneal FLSS was significantly lower in the DQ group at 1 week, 4 weeks and 12 weeks post-op. The OSDI was significantly lower in the DQ group at 1 week post-op. CONCLUSIONS: Use of 3% diquafosol tetrasodium after surgery improved ocular dryness and increased the tear film stability.
Fluorescein ; Humans ; Hyaluronic Acid ; Keratomileusis, Laser In Situ ; Osmolar Concentration ; Prospective Studies ; Tears

PURPOSE: We compared the results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the correction of hyperopia. METHODS: Patients who underwent PRK or LASIK, under +6.00 diopters (D) hyperopia and under −2.00 D astigmatism were included. In total, 21 patients (38 eyes) underwent PRK surgery and 25 patients (41 eyes) underwent LASIK surgery. We compared the visual acuity, refractive error, safety, and efficacy between the two groups. RESULTS: The manifest refractive spherical equivalent (MRSE) of the PRK and LASIK groups at 1 and 3 months after surgery was significantly different between the two groups (p < 0.05). However, the MRSE was not significantly different at postoperative 6 and 12 months between the two groups. The uncorrected visual acuity (UCVA) of the PRK and LASIK groups at 1 month after surgery was significantly different between the two groups (p < 0.05). However, the UCVA was not significantly different at postoperative 3, 6, and 12 months between the two groups. The best-corrected visual acuity was not significantly different at postoperative 1, 3, 6, and 12 months between the two groups. The safety index was not significantly different between the two groups at postoperative 1, 3, 6, and 12 months. The efficacy index of the PRK group was lower than that of the LASIK group at 1 month after surgery. However, the efficacy index was not significantly different at postoperative 3, 6, and 12 months between the two groups. There was no statistically significant difference between the predictability of the two groups at postoperative 1 year. CONCLUSIONS: After PRK treatment, temporary myopic deviation was observed after 1 month, but there was no significant difference between the two treatments after 3 months of follow-up. In the correction of hyperopia, there was no significant difference between PRK and LASIK in efficacy or safety.
Astigmatism ; Follow-Up Studies ; Humans ; Hyperopia ; Keratomileusis, Laser In Situ ; Photorefractive Keratectomy ; Refractive Errors ; Visual Acuity

PURPOSE: To investigate the clinical effects of different orientation and magnitude of cyclotorsion on the compensation capacity of the WaveLight EX500 photorefractive keratectomy (PRK) platform. METHODS: This retrospective study comprised 400 eyes of 200 patients who underwent bilateral simultaneous PRK due to compound myopic astigmatism. The subjects were separated according to the orientation of cyclotorsion into incyclotorsion and excyclotorsion groups, and by the magnitude of cyclotorsion into group 1 (0.50 to 2.50 degrees), group 2 (3.00 to 5.00 degrees), group 3 (5.50 to 7.50 degrees), and group 4 (8.00 to 9.50 degrees). RESULTS: The mean magnitude of cyclotorsion was 3.50 ± 2.4 degrees (0.50 to 9.50 degrees) in the incyclotorsion group and 3.32 ± 2.3 degrees (0.50 to 9.50 degrees) in the excyclotorsion group (p = 0.617). The postoperative refractive outcomes of the incyclotorsion and excyclotorsion groups were similar (p > 0.05 for all). The postoperative mean cylindrical refractive error was −0.32 ± 0.3 diopters (D, −1.25 to 0.00 D) in group 1, −0.47 ± 0.2 D (−2.00 to 0.00 D) in group 2, −0.62 ± 0.2 D (−1.00 to −0.25 D) in group 3, and −0.91 ± 0.2 D (−1.50 to −0.50 D) in group 4 (p < 0.001). Preoperative cylindrical refractive error was positively correlated with magnitude of cyclotorsion (r = 0.125 and p = 0.013), which was also positively correlated with postoperative cylindrical refractive error (r = 0.600 and p < 0.001). CONCLUSIONS: Incyclotorsion and excyclotorsion can be equally compensable in the WaveLight EX500 PRK platform for compound myopic astigmatism. A value of ≤2.50 degrees cyclotorsion magnitude was observed to be more compensable than higher degrees of cyclotorsion magnitude. Preoperative high astigmatism was associated with high cyclotorsion magnitude, which was also associated with a high degree of postoperative astigmatism.
Astigmatism ; Compensation and Redress ; Humans ; Myopia ; Photorefractive Keratectomy ; Refractive Errors ; Refractive Surgical Procedures ; Retrospective Studies

Presbyopia is an age-related condition that progressively decreases the ability to focus on near objects. Minimally invasive surgical techniques have been developed to improve near vision, including laser in situ keratomileuses (LASIK) and corneal inlay. Most have similar approaches using monovision or increasing the depth of focus. Monovision laser refractive surgery is a combination of conventional LASIK, LASIK which creates a multifocal cornea (central near or peripheral near) and aspheric micro-monovision LASIK with a special ablation profile, which develops spherical aberration. Conductive keratoplasty is a method that uses radiofrequency energy to shrink the mid-peripheral corneal stromal tissue. However, it is not used because of regression. A corneal inlay is a small device that is implanted in the corneal flap or pocket made by a femtosecond laser. It is inserted into the non-dominant eye. There are various inlays such as the Flexivue Microlens (refractive), Raindrop (corneal shape-changing), and KAMRA (small-aperture) inlays. However, the safety and effectiveness of these inlays have not been proven over a long follow-up period, so care is required when performing inlay implantation. All presbyopia treatments can improve near vision but also have limitations and side effects such as reduced far vision, contrast sensitivity, or increased glare. Therefore, it is essential to select patients carefully. Mechanisms associated with presbyopia are not fully understood, and presbyopia remains challenging for ophthalmologists.
Contrast Sensitivity ; Cornea ; Corneal Transplantation ; Follow-Up Studies ; Glare ; Humans ; Inlays ; Keratomileusis, Laser In Situ ; Methods ; Presbyopia ; Refractive Surgical Procedures ; Vision, Monocular