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Shedding light on novel approach to artificial cornea
摘要： Arti?cial human corneas that could circumvent the problem of limited donors or ethical concerns have been developed by scientists at Newcastle University. These are the ?rst human corneas to have been 3D printed. The cornea is outermost, transparent layer of the eye, which covers the iris and pupil and plays a role in focusing light on to the retina. The team demonstrated a proof of principle experiment in which they have taken human corneal stromal cells from a healthy donor cornea, mixed them with alginate and collagen and created 3D bio printer ink. Using a conventional commercially available 3D bio-printer, they were able to extrude the mixture to form increasing concentric circles allowing them to fabricate an arti?cial human cornea from actual cells within ten minutes.
关键词： artificial cornea,hydrogel,tissue engineering,bio-ink,3D printing
更新于2025-09-23 15:21:01
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Reproducibility of Central Corneal Thickness Measurements in Normal Eyes Using the Zeiss Cirrus 5000 HD-OCT and Pentacam HR
摘要： Objectives: To determine the repeatability and reproducibility of Central Corneal Thickness (CCT) measurements using two different anterior segment imaging modalities, including those obtained with the new anterior segment lens attachments for the Cirrus 5000 HD-OCT. Methods: A total of 32 eyes from 16 normal volunteers (8 male, 8 female) were enrolled in this prospective study. CCT was measured by the same examiner using the Cirrus 5000 HD-OCT and Pentacam HR. The results of CCT obtained by each method were averaged and compared using t-test analysis. The agreement between the measurement methods was evaluated. Coefficient of Repeatability (CoR) and Intra-Class Correlation Coefficient (ICC) were computed. Results: The mean measurements taken with the Cirrus OCT anterior chamber lens (CCTAC), HD cornea lens (CCTHDC) and pachymetry scans (CCTPach) were 545.35 ± 31.02, 537.87 ± 26.82, and 532.04 ± 29.82 μm, respectively. The mean CCT obtained with the Pentacam (CCTPent) was 545.51 ± 30.71 μm. CCTPent were significantly higher than CCTHDC and CCTPach (p< 0.0001). In contrast, the CCTPent and CCTAC were similar (p=0.87). CCT, as evaluated by the two different instruments, showed excellent correlation (r > 0.98, p< 0.0001) with an ICC > 0.99 (95% CI, 0.97 – 0.99). CoR was the highest for CCTPach (3.7 ± 1.4, 95% CI (3.0- 4.6)). Conclusion: CCT measurements from the Cirrus OCT using the new anterior segment lens attachments and the Pentacam HR are highly correlated. This should allow the use of a standardized correction factor if necessary to inter-relate the measurements between the two devices.
关键词： Imaging,Central corneal thickness,Cornea,Optical coherency tomography,Scheimpflug technology,Pachymetry
更新于2025-09-23 15:21:01
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Application of Femtosecond Laser in Anterior Segment Surgery
摘要： Femtosecond laser (FSL) is a near-infrared laser that can create reliable and reproducible tissue cutting with minimal damage to adjacent tissue. As the laser can also create incisions with various orientations, depths, and shapes, it is expected to be a useful tool for anterior segment surgery, such as cornea, refractive, and cataract surgery. In this review, the authors will introduce the application of FSL in various anterior segment surgeries and discuss the results of studies regarding the efficacy and safety of FSL in cornea, refractive, and cataract surgery. Experimental studies regarding the potential use of FSL will also be introduced. The studies discussed in this review suggest that FSL may be a useful tool for improving the prognosis and safety of surgeries of the anterior segment.
关键词： anterior segment surgery,Femtosecond laser,cataract surgery,refractive surgery,cornea surgery
更新于2025-09-23 15:19:57
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Effects of 1% cyclopentolate hydrochloride on anterior segment parameters obtained with Pentacam in young adults
摘要： Purpose: To investigate the effects of topically applied 1% cyclopentolate hydrochloride on anterior segment parameters obtained with a Pentacam rotating Scheimpflug camera in healthy young adults. Methods: Anterior segment analyses of 25 eyes from 25 young adults (Group 1), before and after 45 min of 1% cyclopentolate hydrochloride application, were performed. For a control group (cycloplegia-free, Group 2), 24 eyes of 24 age- and sex-matched healthy cases were evaluated twice at 45 min intervals. The results obtained from the groups were compared statistically. Results: The mean ages of the groups were 23.04 ± 3.42 (range, 18-29) and 22.4 ± 2.05 (range, 18-27) years for Groups 1 and 2, respectively (p=0.259). In Group 1, measurements between the two analyses were significantly different for the values of anterior chamber depth (ACD), anterior chamber angle (ACA), and anterior chamber volume (ACV) (p<0.05), whereas no statistical difference was found for the central corneal thickness (CCT) and keratometry (K1, K2) measurements. In Group 2, none of these parameters were statistically different between the two analyses. Conclusions: Topically applied 1% cyclopentolate hydrochloride caused an increase in the ACD and ACV values, and a decrease in the ACA value. However, it had no significant effect on the CCT and keratometry measurements. It is important to consider these effects when using the Pentacam device on young adults with cycloplegia and when applying it for various reasons.
关键词： Corneal pachymetry,Cornea,Techniques, measures, measurement equipment,Cyclopentolate/administration and dosage,Biometry
更新于2025-09-19 17:15:36
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Riboflavin/ultraviolet A-induced collagen cross-linking in rabbit corneal scar
摘要： ● AIM: To evaluate the biomechanical stability of the corneal scar treating with riboflavin and ultraviolet A (UVA). ● METHODS: Totally 86 New Zeal rabbits were divided into control group (group A, n=8) and trauma groups [group B (n=27), group C (n=24) and group D (n=27)]. Then groups B, C and D were divided into three sub-groups according to the time points of sacrifice, i.e. groups Ba, Ca and Da (4wk, n=8); Bb, Cb and Db (6wk, n=8); Bc (n=11), Cc (n=8) and Dc (8wk, n=11). The right corneas of these 78 rabbits in the trauma groups were penetrated. Group B were only sutured. Group C were treated with corneal cross-linking (CXL) immediately after suturing. Group D were treated with CXL seven days after suturing. The corneal scar strips of 4.0×10.0 mm2 were cut and the stress and Young’s modulus at 10% strain were evaluated. Samples from the three rabbits of group Bc and three of group Dc were used to measure the expression of alpha smooth muscle action (α-SMA). ● RESULTS: The mechanical strength of the corneal scar increased with time, and was strongest at 8wk after the injury. The ultimate stress of corneal scar (group D) were 2.17±0.52 MPa, 2.92±0.63 MPa, and 4.21±0.68 Mpa at 4wk, 6wk and 8wk, respectively; Young’s modulus were 10.94±1.57 MPa, 11.16±2.50 MPa, and 13.36±2.10 Mpa, which were higher than that of other groups except for normal control. The expression of α-SMA in group B and group D were 0.28±0.11 and 0.65±0.20, respectively, and the difference was statistically significant (P=0.048). ● CONCLUSION: CXL with riboflavin/UVA at seven days after suturing improved the biomechanical properties of corneal scars most effectively in the present study.
关键词： corneal penetrating injury,biomechanics,crosslinking,cornea,rabbit
更新于2025-09-19 17:15:36
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Small-incision lenticule extraction in a patient with high astigmatism and nystagmus
摘要： Small-incision lenticule extraction (SMILE) was performed in a patient with high astigmatism and nystagmus. The patient presented for a refractive surgery evaluation with a manifest refraction of -0.50 -6.00 × 137 (20/40-1) in the right eye and -2.25 -2.25 × 30 (20/40-1) in the left eye. The patient was deemed suitable for corneal laser refractive surgery. Consideration was given to SMILE, laser in situ keratomileusis, and photorefractive keratectomy. It was decided SMILE was the best option given that the refractive portion of the procedure is performed while the cornea is immobilized by suction. The treatment was uneventful, and the final manifest refraction was +0.25 -0.25 × 130 (20/40) in the right eye and +0.25 diopter sphere (20/40) in the left eye. Topography was normal, showing a well-centered treatment zone. This case highlights an additional use for SMILE, given its ability to immobilize the cornea during treatment.
关键词： astigmatism,SMILE,refractive surgery,cornea immobilization,nystagmus
更新于2025-09-19 17:15:36
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In vivo slit scanning confocal microscopic observation in a patient with moderate and severe keratoconus: a case report
摘要： A 22-year-old Indian female was referred to Sg Buloh hospital with the diagnosis of bilateral keratoconus. On examination, slit lamp biomicroscopy and corneal topography revealed stage 3 keratoconus in the right eye and stage 2 keratoconus in the left eye. Corneal cell morphology in both eyes was evaluated using confocal microscope. In qualitative observation, almost all corneal layers in right eye except endothelium were partially or completely obscured by haze. Additionally, morphological alterations, such as elongation of keratocyte nuclei and cluster of cells, and dark bands in the anterior stroma were observed in right eye. In the left eye, the amount of haze was less, allowing better visibility of the corneal layers compared with the right eye. The dark bands were evident in the posterior stroma. Quantitative analysis showed that anterior and posterior stromal keratocyte density and endothelium cell density were relatively low in the right eye (834.0, 700.5, and 2,133 cells/mm2, respectively) compared with the left eye (934.1, 750.6, and 2,361 cells/mm2, respectively). In this case, the right eye, exhibiting stage 3 keratoconus, showed more morphological alteration, particularly in the anterior stroma compared with the left eye with stage 2 keratoconus. Increased severity of the disease can explain these differences in corneal cell morphology.
关键词： confocal microscopy,keratocyte,stromal haze,striae,cornea,keratoconus
更新于2025-09-19 17:15:36
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Differences in Simulated Refractive Outcomes of Photorefractive Keratectomy (PRK) and Laser In-Situ Keratomileusis (LASIK) for Myopia in Same-Eye Virtual Trials
摘要： The use of computational mechanics for assessing the structural and optical consequences of corneal refractive procedures is increasing. In practice, surgeons who elect to perform PRK rather than LASIK must often reduce the programmed refractive treatment magnitude to avoid overcorrection of myopia. Building on a recent clinical validation study of finite element analysis (FEA)-based predictions of LASIK outcomes, this study compares predicted responses in the validated LASIK cases to theoretical PRK treatments for the same refractive error. Simulations in 20 eyes demonstrated that PRK resulted in a mean overcorrection of 0.17 ± 0.10 D relative to LASIK and that the magnitude of overcorrection increased as a function of attempted correction. This difference in correction closely matched (within 0.06 ± 0.03 D) observed differences in PRK and LASIK from a historical nomogram incorporating thousands of cases. The surgically induced corneal strain was higher in LASIK than PRK and resulted in more forward displacement of the central stroma and, consequently, less relative flattening in LASIK. This FE model provides structural confirmation of a mechanism of action for the difference in refractive outcomes of these two keratorefractive techniques, and the results were in agreement with empirical clinical data.
关键词： laser in situ keratomileusis (LASIK),refractive surgery,cornea,photorefractive keratectomy (PRK),finite element analysis
更新于2025-09-16 10:30:52
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Dynamic Scheimpflug Ocular Biomechanical Parameters in Healthy and Medically Controlled Glaucoma Eyes
摘要： To evaluate the relationship between biomechanical parameters measured with a dynamic Scheimpflug analyzer and glaucoma. Cross-sectional observational data of 47 eyes of 47 consecutive subjects with medically controlled primary open-angle glaucoma and 75 eyes of 75 healthy subjects examined with a dynamic Scheimpflug analyzer (Corvis ST) were retrospectively investigated. Eight biomechanical parameters were compared between eyes with and without glaucoma using multivariable models adjusting for intraocular pressure (IOP), central corneal thickness, age, and axial length. In multivariable models, glaucoma was negatively correlated with A1 time (P < 0.001, coefficient = ?0.5535), A2 time (P = 0.008, coefficient = ?0.1509), radius (P = 0.011, coefficient = ?0.4034), and whole eye movement (P < 0.001, coefficient = ?0.0622). Negative correlation between glaucoma and 3 parameters (A1 time, A2 time, and radius) consistently indicate larger deformability of the cornea and negative correlation between glaucoma and whole eye movement indicate smaller eye movement, in glaucoma eyes. There were significant correlations of many biomechanical parameters with other baseline factors (8 parameters with IOP, 2 with central corneal thickness, 4 with age, and 7 with axial length). Eyes with medically controlled glaucoma were more deformable than healthy eyes, which may increase the risk of optic nerve damage through an underestimation of IOP and biomechanical vulnerability of the globe. Many parameters showed a significant correlation with baseline factors, suggesting the importance of adjustment for these confounding factors when evaluating the correlation between biomechanical parameters and ocular diseases. These results suggest the relevance of measuring biomechanical properties of glaucoma eyes for accurate IOP measurement and risk assessment.
关键词： intraocular pressure,glaucoma,cornea,biomechanics,Scheimpflug photography
更新于2025-09-12 10:27:22
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Femtosecond Laser-Assisted Deep Lamellar Descemet Membrane Endothelial Keratoplasty for the Treatment of Endothelial Dysfunction Associated With Posterior Stromal Scarring
摘要： To describe an alternative surgical approach, femtosecond laser-assisted deep lamellar Descemet membrane endothelial keratoplasty (Femto-DL-DMEK), for the treatment of posterior corneal stromal scarring associated with endothelial diseases. Case report of a 52-year-old man with pseudophakic bullous keratopathy and posterior corneal scarring secondary to viral endotheliitis who underwent Femto-DL-DMEK. The surgical technique was as follows: First, a manual lamellar dissection plane was created at approximately 75% to 85% depth through a 5.0-mm superior scleral incision. One week later, using a femtosecond laser, an intersecting posterior side cut of 8.2 mm diameter was created. Subsequently, the dissected posterior recipient disk was removed from the anterior chamber through a 3.2-mm limbal incision. Finally, an 8.0-mm DMEK graft was placed. The patient’s uncorrected distance visual acuity improved from 20/200 (0.15; decimal) preoperatively to 15/25 (0.6) after surgery; corrected distance visual acuity improved from 20/200 (0.15) to 20/25 (0.9) with a residual refraction of +1.0–0.50 at 140 degrees. Endothelial cell count was 2062 cell/mm2 6 months after surgery. No intra- or postoperative complications were noted. As long as the anterior and mid-stroma are unaffected, those with endothelial diseases associated with opacification of the posterior stroma can benefit from endothelial keratoplasty through a Femto-DL-DMEK procedure, avoiding all well-known drawbacks of penetrating keratoplasty.
关键词： posterior corneal scarring,cornea,endothelial failure,Femtosecond laser,endothelial keratoplasty,transplant,DMEK
更新于2025-09-12 10:27:22