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Pharmacologic Alternatives to Riboflavin Photochemical Corneal Cross-Linking: A Comparison Study of Cell Toxicity Thresholds
摘要： PURPOSE. The efficacy of therapeutic cross-linking of the cornea using riboflavin photochemistry (commonly abbreviated as CXL) has caused its use to become widespread. Because there are known chemical agents that cross-link collagenous tissues, it may be possible to cross-link tissue pharmacologically. The present study was undertaken to compare the cell toxicity of such agents. METHODS. Nine topical cross-linking agents (five nitroalcohols, glyceraldehyde [GLYC], genipin [GP], paraformaldehyde [FA], and glutaraldehyde [GLUT]) were tested with four different cell lines (immortalized human corneal epithelial cells, human skin fibroblasts, primary bovine corneal endothelial cells, and immortalized human retinal pigment epithelial cells [ARPE-19]). The cells were grown in planar culture and exposed to each agent in a range of concentrations (0.001 mM to 10 mM) for 24 hours followed by a 48-hour recovery phase. Toxicity thresholds were determined by using the trypan blue exclusion method. RESULTS. A semiquantitative analysis using five categories of toxicity/fixation was carried out, based on plate attachment, uptake of trypan blue stain, and cellular fixation. The toxicity levels varied by a factor of 103 with the least toxic being mononitroalcohols and GLYC, intermediate toxicity for a nitrodiol and nitrotriol, and the most toxic being GLUT, FA, GP, and bronopol, a brominated nitrodiol. When comparing toxicity between different cell lines, the levels were generally in agreement. CONCLUSIONS. There are significant differences in cell toxicity among potential topical cross-linking compounds. The balance between cross-linking of tissue and cell toxicity should be borne in mind as compounds and strategies to improve mechanical tissue properties through therapeutic tissue cross-linking continue to develop.
关键词： protein cross-linking,cornea,cellular toxicity,keratoconus
更新于2025-09-23 15:23:52
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Analysis of corneal esthesia in patients undergoing photorefractive keratectomy
摘要： Purpose: To quantitatively analyze corneal esthesia in patients undergoing photorefractive keratectomy (PRK) surgery. Methods: Forty-five patients selected for PRK in one eye underwent corneal esthesia using a Cochet-Bonnet esthesiometer preoperatively and 30 and 90 days postoperatively. Patients with a refractive diopter error of 4 or greater received intraoperative 0.02% mitomycin C for 20 s. Results: Twenty-four (53.3%) of the 45 eyes received intraoperative 0.02% mitomycin. Decreased sensitivity was observed on postoperative day 30. By postoperative day 90, corneal esthesia had normalized but remained 14.9% lower than preoperative levels. In the mitomycin group, no recovery of corneal esthesia to normal sensitivity levels was observed. The mean esthesiometer level was 39.2 mm on postoperative day 90 (P<0.001). Conclusions: The results of the present study demonstrate recovery of corneal esthesia to normal levels at 90 days postoperatively in patients who did not receive mitomycin C. In patients administered mitomycin C, a 23.59% reduction in the corneal touch threshold was observed compared with preoperative levels indicating a failure of recovery to normal levels.
关键词： Mitomycin,Photorefractive keratectomy,Cornea,Prospective studies,Myopia
更新于2025-09-23 15:23:52
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[IEEE 2018 Second International Conference on Inventive Communication and Computational Technologies (ICICCT) - Coimbatore (2018.4.20-2018.4.21)] 2018 Second International Conference on Inventive Communication and Computational Technologies (ICICCT) - Futuristic Surveillance Spectacles
摘要： Nowadays, spectacles are common which are used to flaunt off your style and stand out among the others in a crowd. But why not disguise some special features within it apart from the style and eye power? There have been many attempts to enhance the way we use our daily commodities in order to expand its range of effectiveness. And so, we strive for further utilizing the spectacles not only as a wearable device but also as a productive device. We propose for a surveillance spectacle which is both swanky and with some extra applications. One of the feature is a camera incorporated at the nose bridge of a spectacle to capture images or videos of the nearby surroundings. This can be used as a hands-free camera for personal as well as for professional purposes. Also, the camera along with a lens can be used as a projector for displaying the captured images/videos. We have further implemented a Bluetooth module which can be linked to any wireless printer so as to print out any images. Finally, the most interesting of all, we have made an attempt to add a stress measurement algorithm through which any human eye's stress can be calculated and will further indicate users about the amount of stress on the eye indirectly cautioning them to give some rest to the eye if it is in a humongous amount of stress. Therefore, this concept is what we believe will improve human life and build up a user-friendly environment.
关键词： Stress Management,Bluetooth Module,Printing,Cornea,Projection
更新于2025-09-23 15:23:52
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Photoactivated chromophore corneal cross-linking (PACK-CXL) for treatment of severe keratitis
摘要： Purpose: To report our experience with photoactivated chromophore corneal cross-linking (PACK-CXL) for treating keratitis patients. Methods: This retrospective study consists of 27 eyes of 26 patients with infectious keratitis treated with PACK-CXL at the Helsinki University Hospital between 2009 and 2017. Patients were treated with antibiotics/antifungal medications and underwent PACK-CXL procedure due to lack of clinical response or severe corneal melts. For twenty patients, amniotic membrane transplant (AMT) was done during the same day. Follow-up after cross-linking ranged from 1 week to 12 months. Results: Sixteen infections were related to contact lens wear. Of the 19 eyes showing positive culture, the predominant micro-organism was Pseudomonas aeruginosa (9 cases). The average re-epithelization time was 13 days and in 15 cases (56%) the re-epithelization occurred within one week. In 26 eyes, visual acuity increased and seven patients (26%) had a ?nal visual acuity more or equal to 0.5 (20/40) Snellen. Conclusions: PACK-CXL seems to be a safe and potential option for treating patient with infectious keratitis who do not respond to antibiotic therapy.
关键词： corneal cross-linking,infectious keratitis,ribo?avin,cornea,PACK-CXL
更新于2025-09-23 15:22:29
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Confocal Cornea Microscopy Detects Involvement of Corneal Nerve Fibers in a Patient with Light-Chain Amyloid Neuropathy Caused by Multiple Myeloma: A Case Report
摘要： Changes in the subbasal corneal plexus detected by confocal cornea microscopy (CCM) have been described for various types of neuropathy. An involvement of these nerves within light-chain (AL) amyloid neuropathy (a rare cause of polyneuropathy) has never been shown. Here, we report on a case of a patient suffering from neuropathy caused by AL amyloidosis and underlying multiple myeloma. Small-fiber damage was detected by CCM.
关键词： Small-fiber neuropathy,Confocal cornea microscopy,Skin biopsy,Amyloid neuropathy,Multiple myeloma
更新于2025-09-23 15:22:29
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Six-month outcomes of corneal crosslinking with dextran-free isotonic riboflavin solution
摘要： Purpose: To analyze the short-term clinical and topographic outcomes in patients with keratoconus after corneal collagen cross-linking treatment (CXL) with dextran-free isotonic riboflavin solution. Methods: In this retrospective case series, 26 eyes from 26 patients with keratoconus were studied. The best corrected visual acuity (BCVA) and refractive and topographic findings were analyzed at a 6-month follow-up. Results: The mean BCVA (Snellen lines) values before and 1, 3, and 6 months after CXL were 0.51 ± 0.2, 0.48 ± 0.2, 0.57 ± 0.2, and 0.64 ± 0.2, respectively, and the difference between the preoperative and 6-month values was statistically significant (p=0.006). The mean spherical equivalent refraction decreased from -5.6 ± 2.4 diopters (D) preoperatively to -5.0 ± 2.1 D, and mean simulated keratometry decreased from 48.5 ± 2.5 D to 47.8 ± 2.6 D at 6 months. (p=0.145 and p=0.001, respectively). In addition, the maximum keratometry decreased progressively and significantly from the preoperative value during follow-up (p=0.003). The central and minimal corneal thicknesses, including those of the epithelium, also decreased from 442.8 ± 25.6 μm and 430.5 ± 23.9 μm preoperatively to 420.7 ± 31.8 μm and 409.3 ± 28.7 μm at the most recent follow-up (p<0.001), respectively. No intraoperative or postoperative complications were observed. Conclusions: CXL with dextran-free isotonic riboflavin solution appears to be a safe treatment alternative for keratoconus and yields sustained short-term improvements in visual acuity, keratometric readings, and corneal thickness. However, long-term results are needed to confirm these outcomes.
关键词： Dextrans,Riboflavin/therapeutic use,Collagen,Visual acuity,Ultraviolet rays,Cornea,Cross-linking reagents
更新于2025-09-23 15:22:29
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On the reliability (repeatability) of single pachymetry measures taken with specular microscope-based assessments of the human corneal endothelium
摘要： Purpose: To assess agreement between 3 measures of central corneal thickness (CCT) taken over a few minutes from nominally normal eyes with a non-contact specular microscope. Methods: 100 eyes from 100 healthy adults (with an average age of 22 y) were assessed using the Topcon 3000 P instrument to obtain a high quality image of the endothelium and pachymetry. Results: The group mean CCT values from the 1st, 2nd and 3rd measures were 0.519, 0.520 and 0.520 mm, but the sets of values could di?er by between – 0.020 mm and + 0.029 mm, i.e. between - 4.0 and + 5.6% of the average values. Paired comparisons (e.g. 2nd vs. 1st set) indicated limits of agreement (LoA) to be between - 0.020 and + 0.020 mm of the averaged value. Across the 3 measures, the averaged SD was 0.005 mm to give an estimate of the intra-subject variability (as the coe?cient of variation, COV) of 0.91% (range 0 to 2.3%). The variability in the pachymetry measures was not predictably related to the averaged values of CCT (r = 0.022) or self-reported refractive error of the subjects (r = 0.012). Some repeat pachymetry assessments obviously in-cluded the same region of the endothelium. Conclusions: Single pachymetry measures with a non-contact specular microscope are only likely to be able to generate CCT estimates within +/? 4% of the expected average values. This repeatability is comparable to single image estimates of endothelial cell density and therefore acceptable in most cases.
关键词： Cornea,Pachymetry,Human,Repeat measures,Central corneal thickness
更新于2025-09-23 15:21:21
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Assessment of anterior and posterior corneal indices using two Scheimpflug analyzers
摘要： Purpose: To assess the agreement between the elevation and curvature measurements of the anterior and posterior corneal surfaces obtained using the Galilei Dual Scheimpflug Analyzer and those obtained using the Pentacam single Scheimpflug system. Methods: This prospective, noninterventional, diagnostic study was conducted at the Department of Ophthalmology at the American University of Beirut (Medical Center) and included 60 eyes of 60 consecutive patients. Measurements were obtained using 2 different Scheimpflug analyzers (Galilei and Pentacam). The best-fit sphere was set at 8 mm in both machines. Pachymetry (CCT), anterior elevation (AE) and posterior elevation (PE), and curvature were assessed. Pearson’s correlation coefficients, comparison of means, and Bland-Altman plots were used to evaluate agreement between the 2 systems. Results: The average CCT (at the corneal apex) was 533 ± 35 μm and 532 ± 37 μm (p=0.980), the average central AE was 1.25 ± 3.95 μm and 2.29 ± 5.28 μm (p=0.964), and the average central PE was 4.19 ± 8.18 μm and 5.42 ± 14.05 (p=0.956) μm with the Galilei and Pentacam, respectively. Conclusion: The Scheimpflug analyzers correlated well in the assessment of pachymetry, elevation, and curvature.
关键词： Corneal pachymetry,Photography/instrumentation,Cornea/pathology,Cornea/anatomy & histology,Corneal topography
更新于2025-09-23 15:21:01
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Systematic review and meta-analysis of femtosecond lasera??enabled keratoplasty versus conventional penetrating keratoplasty
摘要： Purpose: The aim of this meta-analysis is to compare femtosecond laser–enabled keratoplasty with conventional penetrating keratoplasty regarding postoperative astigmatism, visual functions, graft rejection, graft failure, and complications. Methods: Eligible studies were retrieved from five mainstream electronic databases, including PubMed, Embase, Ovid MEDLINE, Cochrane Library, and ClinicalTrial.gov. Postoperative topographic astigmatism was set as the primary outcome, and best-corrected visual acuity, spherical equivalent, endothelial cell density, graft rejection, graft failure, and complications were chosen as the secondary outcomes. Standard mean difference and risk ratio were the size effects for continuous data and binomial data, respectively. The data were pooled through either the random-effects model or the fixed-effects model based on data heterogeneity. Moreover, subgroup analyses were conducted when the heterogeneity occurred distinctly (I2 > 50%). Results: A total of seven comparative studies were included. The pooled standard mean difference (?0.32, 95% confidence interval: ?0.74 to 0.10) showed that femtosecond laser–enabled keratoplasty was not superior over conventional penetrating keratoplasty to decrease postoperative topographic astigmatism (p = 0.14). However, best-corrected visual acuity after femtosecond laser–enabled keratoplasty was significantly better than that after conventional penetrating keratoplasty (p = 0.00, standard mean difference: ?0.23, 95% confidence interval: ?0.37 to ?0.10). Furthermore, endothelial cell density after femtosecond laser–enabled keratoplasty was preserved significantly better (p = 0.03, standard mean difference: 0.63, 95% confidence interval: 0.07–1.20). Moreover, spherical equivalent, graft rejection, graft failure, and complications represented no distinct differences between femtosecond laser–enabled keratoplasty and conventional penetrating keratoplasty (p > 0.05). Conclusion: Femtosecond laser–enabled keratoplasty may not be superior over conventional penetrating keratoplasty in decreasing postoperative topographic astigmatism, but might have advantages to achieve best-corrected visual acuity and endothelial cell density preservation. In addition, the two techniques seem to be comparable regarding spherical equivalent, graft rejection/failure, and complications.
关键词： Astigmatism,meta-analysis,femtosecond laser–enabled keratoplasty,conventional penetrating keratoplasty,cornea
更新于2025-09-23 15:21:01
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Hyperopic laser keratorefractive surgery: Do steep corneas have worse outcomes?
摘要： Purpose To report the visual and refractive outcomes of hyperopic patients undergoing laser keratorefractive surgery in preoperatively steep corneas versus a matched control group. Methods Retrospective cohort study. All patients underwent photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) at Care-Vision Laser Centers, Tel-Aviv, Israel, between 1/2000 and 11/2016. Patients were divided into two groups: steep corneas (mean keratometry C 44.00 D) and control group (mean keratometry < 44.00 D). The two study groups were matched by age, gender, sphere and cylinder. Only the right eye of each patient was included. Outcomes included postoperative uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), safety and efficacy indexes, refractive outcomes and retreatment rates. Results Five hundred and two patients were included. Both groups were similar in demographic data, visual acuity and refraction. Postoperatively, the steep corneas group had a significantly higher mean keratometry as compared to the control group (46.52 ± 1.43 D vs 44.58 ± 1.68 D, p < 0.001), Kmin (46.04 ± 1.50 D vs 44.12 ± 1.76 D, p < 0.001) and Kmax (46.99 ± 1.51 D vs 45.03 ± 1.77 D, p < 0.001). Both groups had similar postoperative UDVA and CDVA and achieved a similar final sphere (0.64 ± 0.19 vs 0.54 ± 1.19, p = 0.44) and cylinder (-0.89 ± 0.59 vs -0.86 ± 0.72, p = 0.67). Both groups had a similar efficacy index (0.92 ± 0.22 vs 0.90 ± 0.25, p = 0.33) and similar retreatment rates (4.2% vs 3.5%, p = 0.74). None of the patients in either group underwent more than one retreatment throughout the follow-up period. Conclusions Hyperopic patients with steep corneas undergoing laser keratorefractive surgery can achieve adequate visual and refractive outcomes, similar to control group.
关键词： PRK,LASIK,Keratorefractive surgery,Hyperopia,Steep cornea
更新于2025-09-23 15:21:01