Development of the control system for electron cyclotron resonance heating on J-TEXT tokamak.

A 105 GHz/500 kW/1 s electron cyclotron resonance heating (ECRH) system has been developed on J-TEXT tokamak since 2017. The core component of the ECRH system is a gyrotron manufactured by Gyrotron Complexes Ltd. (GYCOM Ltd.), which generates microwaves of a certain frequency and power. To guarantee safe and stable operation, it is necessary to design a specialized control system. The control system is expected to perform time sequence trigger, protection, signal monitoring, communication, and data acquisition. The hardware is built with real-time processors and data acquisition modules from National Instruments. The control program is realized by LabVIEW. Test results indicate that the control system can commit stable and safe operation of the gyrotron, which guarantees the integrated commissioning tests of the whole ECRH system and ECRH related physics experiments. Under the operation of this control system, the gyrotron can generate microwaves as expected, and the ECRH system is well protected when a fault takes place.

Zinc oxide nanoparticles promotes liver cancer cell apoptosis through inducing autophagy and promoting p53.

OBJECTIVE: Emerging evidence has highlighted the promising potential of the application of Zinc Oxide nanoparticles (nano-ZnO) but the mechanism by how it functions in liver cancer remains elusive. We aimed to explore the effect of nano-ZnO on liver cancer cells. MATERIALS AND METHODS: Liver cancer cells Huh7 cells were transfected with GFP-LC3, and then, treated with DMSO, Sorafenib, and nano-ZnO respectively to set blank group, Sorafenib control group, and nano-ZnO group followed by the analysis of the expression of GFP-LC3, p53, and Caspase by Western blot and RT-qPCR, cell apoptosis and viability by flow cytometry and CCK-8 assay. RESULTS: With a diameter of nano-ZnO 14.13±0.92 nm, the amount of GFP-LC3 protein was increased after treatment of nano-ZnO. Besides, the expressions of GFP-LC3, p53, and Caspase in Sorafenib group and nano-ZnO group were significantly higher than that of control group, while their levels were highest in nano-ZnO group (p<0.05). In nano-ZnO group, the values of D450nm at 24 h, 48h, and 72 h were 0.56±0.06, 0.39±0.05, and 0.22±0.04, respectively, and the apoptotic rate (83.11±2.79%) was significantly lower than that of blank group and control group. CONCLUSIONS: Nano-ZnO induced autophagy, upregulated the p53 gene, and facilitated the apoptosis of liver cancer cells, indicating that nano-ZnO might be a therapeutic approach for the treatment of liver cancer patients.

Changes of anti-ß2 glycoprotein I antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen and d-dimer in guiding venous thrombosis during pregnancy.

OBJECTIVE: This study provides a theoretical basis for the prevention, treatment and diagnosis of venous thrombosis during pregnancy. PATIENTS AND METHODS: Sixty patients with venous thrombosis in gestation period were treated as the research group, including every 30 people in the middle and late pregnancy groups, and the control group randomly selected 33 healthy pregnant women during the same period. The anti-ß2 glycoprotein I antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen, and D-dimer levels were measured in all subjects. RESULTS: Resistance-ß2 glycoprotein I antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen, and compared with the control group, D-dimer levels were significantly increased (p<0.05), but for the middle pregnancy group and late pregnancy group, the difference was not statistically significant (p>0.05). In the control group of pregnant women anti-ß2 glycoprotein Ⅰ antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen, and D-dimer no obvious correlation (p>0.05), Anti-ß2 glycoprotein Ⅰ antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen, D-dimer entry equation are closely related risk factors for venous thrombosis during pregnancy (p<0.05), and D-dimer is the most important. CONCLUSIONS: Vein thrombosis during pregnancy patients anti-ß2 glycoprotein I antibody IgA/G/M, platelet aggregation rate, plasma fibrinogen, and D-dimer in pregnant women group increased significantly compared with the control group, suggesting these above indicators are closely related to Venous thrombosis in pregnant women and associated with the severity of the disease. Vascular endothelial injury plays an important role in phlebothrombosis in gestation period.

Fast island phase identification for tearing mode feedback control on J-TEXT tokamak.

A new method to control the tearing mode (TM) in tokamaks has been proposed [Q. Hu and Q. Yu, Nucl. Fusion 56, 034001 (5pp.) (2016)], according to which, the external resonant magnetic perturbation needs to be applied in certain magnetic island phase regions. Therefore, it is very important to identify the helical phase of magnetic islands in real time. The TM in tokamak plasmas is normally rotating and carries magnetic oscillations, which are known as Mirnov oscillations and can be detected by Mirnov probes. When the O-point or X-point of the magnetic island passes through the probe, the signal will experience a zero-crossing. A poloidal Mirnov probe array and a corresponding island phase identification method are presented. A field-programmable gate array is used to provide the magnetic island helical phase in real time by using multichannel zero crossing detection. This system has been developed on the J-TEXT tokamak and works well. This paper introduces the establishment of the fast magnetic island phase identifying system.

Extensible chip of optofluidic variable optical attenuator.

A core chip of optofluidic variable optical attenuator (VOA) is reported. The chip, with a simple structure, utilizes microfluid and compressed air to regulate the optical attenuation, and it can be expanded to form a number of VOAs by using different microfluidic driving technologies. Three VOAs based on this chip and different driving technologies are introduced. The theoretical and experimental results show that the proposed chip possesses the advantages of large optical attenuation range (> 50dB) and low insertion loss (0.55 dB). Moreover it is a broadband optical device which can be operated in visible and near infrared wavelengths. The proposed chip provides a new method for seeking miniaturized VOAs with good performances, and it is promising to develop a number of different VOAs.

Root tip chromosome karyotype analysis of hyacinth cultivars.

Karyotype analysis in plants helps to reveal the affinity relationships of species and their genetic evolution. The current study aimed to observe chromosome karyotypes and structures of Hyacinthus orientalis. Twenty hyacinth cultivars were introduced from Holland, and their water-cultivated root tips were used as experimental samples. A solution of colchicine (0.02%) and 8-hydroxyquinoline (0.02 M) was used as a 20-h pre-treatment. Subsequently, Carnot I was used for fixation and 45% acetic acid was used for dissociation. The squash method was selected to prepare chromosome spreads for microscopic observation. The basic chromosome number of the hyacinth cultivar was 8, and the number of chromosomes in the diploid, triploid, tetraploid, and aneuploid cultivars was 16, 23, 24, 31, and 32, respectively. The L-type chromosome was predominant in the chromosomal composition. The hyacinth satellite was located on the short arm in numbers equivalent to the ploidy. This satellite is located on the middle-sized chromosome in the fourth group of chromosomes, demonstrating that Hyacinthus has a more primitive evolution than Lilium and Polygonatum. Among 20 hyacinth cultivars, 'Fondant' had the highest level of evolution and a maximum asymmetric coefficient of 61.69%. Moreover, the ratio between the shortest and longest chromosomes in this cultivar was 4.40, and its karyotype was type 2C. This study may elucidate long-term homonym and synonym phenomena. It may also provide a method of cytological identification as well as direct proof of the high outcross compatibility between hyacinth cultivars.

Non-tuberculous mycobacterial keratitis.

Non-tuberculous mycobacteria are environmental, opportunistic pathogens that are increasingly being recognized as important causes of many human diseases. Among them, rapidly growing mycobacteria are the most notorious organisms causing infectious keratitis. Non-tuberculous mycobacterial (NTM) keratitis commonly occurs after trauma or refractive surgery, and can masquerade as fungal, herpetic or amoebic keratitis. Therefore, the diagnosis is often delayed. Prolonged medical treatment and judicious surgical debridement are required in order to eradicate the pathogens. Combination therapy with aminoglycosides, macrolides and fluoroquinolones improves the prognosis and decreases the occurrence of drug resistance. However, regardless of the development of new diagnostic techniques and antimicrobials, NTM keratitis remains a clinical challenge for most ophthalmologists. In this article, we provide a concise introduction to the epidemiological features and clinical characteristics of NTM keratitis, and the modern diagnostic tools used for it. We also summarize the current concepts of prevention and treatment for this potentially devastating condition.

Critical appraisal of ex vivo expansion of human limbal epithelial stem cells.

The stem cells (SCs) of the corneal epithelium located in the limbal basal layer are the ultimate source to maintain corneal epithelial homeostasis. Like other adult tissue-specific SCs, self renewal and fate decision of limbal SCs are regulated by a specialized in vivo microenvironment, termed "niche". Loss of limbal SCs or dysfunction of the limbal niche renders corneas with a unique clinical disease labeled limbal stem cell deficiency (LSCD). Besides transplantation of autologous or allogeneic limbal SCs or amniotic membrane, a new strategy of treating LSCD is to transplant a bio-engineered graft by expanding limbal SCs ex vivo. Herein, we conduct a critical appraisal of six protocols that have successfully been practiced in treating human patients with LSCD, and identify issues whether niche regulation has been disrupted or maintained during isolation and expansion. Consequently, we propose a future direction that may circumvent the potential pitfalls existing in these conventional protocols by preserving the interaction between limbal SCs and their native niche cells during isolation and expansion. Such an approach may one day help realize considerable promise held by adult SCs in treating a number of diseases.

Effect of oral azithromycin in the treatment of chlamydial conjunctivitis.

PURPOSE: To assess the efficacy of oral azithromycin in the treatment of chlamydial conjunctivitis. METHODS: We performed a retrospective study in patients with clinically suspected chlamydial conjunctivitis who underwent conjunctival swab sampling for Chlamydia direct fluorescent antibody (DFA) tests between 1 January 2006 and 31 December 2006. Patients with positive DFA results were orally administered azithromycin once a week for 2 consecutive weeks. If DFA examinations still showed positive results after 4 weeks, additional azithromycin was orally administered once. The DFA tests were repeated 4 weeks later, and this was continued until the DFA tests showed negative results. RESULTS: Among the 67 suspected patients, 45 (67.2%) showed positive results from the DFA tests, of whom 42 received treatment. After the first 2 weeks, only 27 patients returned to the clinic and completed the treatment. The test results of 19 (70.4%) patients became negative after the treatment with two weekly doses of oral azithromycin. Among the remaining eight patients, four (14.8%) needed an additional dose of oral azithromycin, and the other four (14.8%) required two additional doses. All 27 patients tolerated the treatment well, with an adverse event of mild gastritis in only one patient. CONCLUSIONS: Two weekly doses of oral azithromycin were effective and well tolerated in the treatment of chlamydial conjunctivitis. However, more than one course of treatment was necessary in some patients.

Comparison of fluoroquinolones: cytotoxicity on human corneal epithelial cells.

PURPOSE: To compare the cytotoxicity of different fluoroquinolones (FQs) towards human corneal epithelial cells (HCECs). METHODS: HCECs were incubated with FQs (norfloxacin, ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin, and gatifloxacin), both as commercial ophthalmic formulations and as unpreserved solutions. Cells incubated in different formulations of gentamicin, cefazolin, and benzalkonium chloride (BAC) were also compared. A cell viability assay, using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, was used to evaluate the drug effects on cell viability after five incubation times (30 min, 1 h, 4 h, 8 h, and 24 h). Transepithelial electrical resistance (TEER) was measured with a voltohmmeter to help understand changes in paracellular permeability at five time points (4 h, 8 h, 12 h, 24 h, and 48 h). Cell morphology was observed with an inverted fluorescence microscope, with multiple stage position and in time-lapse mode. RESULTS: The preserving solutions and BAC at concentrations above 0.005% significantly decreased cell viability, when assayed by MTS. Increased paracellular permeability and decreased membrane integrity were also observed by TEER measurements and inverted fluorescence microscopy. Ofloxacin and levofloxacin were both free of preservatives and showed the least cytotoxicity towards HCECs in commercial FQ eye drops. CONCLUSIONS: The cytotoxicity observed with FQ eye drops seems to be caused mainly by the preservative, which induced a significant decrease in membrane integrity and increased paracellular permeability. We found the new generation of FQs (moxifloxacin and gatifloxacin) no less cytotoxic towards HCECs than the old generation ones.

A 100 nm thick InGaN/GaN multiple quantum-well column-crystallized thin film deposited on Si(111) substrate and its micromachining.

A 100 nm thick InGaN/GaN multiple quantum-well column-crystallized thin film was deposited on Si(111) substrate, with InN as the interlayer, by molecular beam epitaxy. The diameter of the column crystal is about 40 nm. Transmission electron microscopy images showed clear five-period well layers. Photoluminescence measurements demonstrated a wide emission wavelength from about 500 to 800 nm with the full width at half maximum of 107 nm at room temperature. An unusual photoluminescence peak position shift was observed from the optical measurement. The selected area electron diffraction image demonstrated the hexagonal wurtzite structure of the column crystal. A self-supported GaN-based active subwavelength grating was proposed, and the active subwavelength grating structure was fabricated from the InGaN/GaN quantum-well thin film by a Si micromachining process.

A comparison of the effect of carbomer-, cellulose- and mineral oil-based artificial tear formulations.

PURPOSE: To compare the efficacy, safety, and local tolerance between carbomer-based artificial tears, cellulose-, and mineral oil-based artificial tears. METHODS: A randomized, open-label, parallel-group comparative 28-day study was designed for 67 patients who were randomized into three treatment groups. Measurements included the scoring of total subjective symptoms and objective signs, Schirmer-Jones test values, and tear break-up time (BUT) at baseline, and after 2 and 4 weeks of treatment. Safety of study treatment was also assessed. Outcomes measured at baseline and 2 and 4 weeks follow-up included the scoring of total subjective symptoms and objective signs, Schirmer-Jones test values, and tear BUT, subjective assessments, and safety. RESULTS: There were no differences regarding total scores, Schirmer-Jones test, or tear BUT at baseline among these three groups at 2 and 4 weeks. Patients in all three treatment groups experienced a significant improvement from baseline in total scores and Schirmer-Jones test values after treatment. Subjective assessment was better with carbomer-based treatment. CONCLUSIONS: Each artificial tear formulation successfully relieved symptoms and signs of keratoconjunctivitis sicca. The tolerance of carbomer-based artificial tears was comparable to that of cellulose- and mineral oil-based artificial tears.

Laser in situ keratomileusis for the correction of myopia and myopic astigmatism.

PURPOSE: To evaluate the efficacy, safety, predictability, and surgically induced astigmatism (SIA) of laser in situ keratomileusis (LASIK) for the correction of myopia and myopic astigmatism. SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This retrospective study comprised 69 eyes that had LASIK to correct myopia and 74 eyes that had LASIK to correct myopic astigmatism. The excimer laser keratectomy was performed using a Summit Apex Plus machine. Refraction, visual acuity, and computerized corneal videokeratography data from the preoperative and postoperative examinations were collected. The astigmatic change was calculated by the Alpins vector analysis method. RESULTS: The preoperative spherical equivalent at the glasses plane in the myopia and myopic astigmatism groups was -8.08 diopters (D) and -9.73 D, respectively. At 6 months, the spherical equivalent and residual corneal astigmatism were -0.25 D and 0.85 D, respectively, in the myopia group and -0.71 D and 0.82 D, respectively, in the myopic astigmatism group. In the myopia group, 88% of eyes were within +/-1.0 D of the intended myopia correction and in the myopic astigmatism group, 85% were within +/-1.0 D of the targeted spherical equivalent and 90% were within +/-1.0 D of the intended astigmatism correction. The uncorrected visual acuity was 20/40 or better in 94.1% of eyes in the myopia group and 92.5% of eyes in the myopic astigmatism group. The SIA magnitude was 0.66 D with the axis randomly distributed in the myopia group. The mean astigmatism correction index was 0.97, the mean magnitude of error was 0.13 D +/- 0.62 (SD), and the mean angle of error was -3.70 +/- 13.73 degrees in the myopic astigmatism group. CONCLUSION: Laser in situ keratomileusis had similar predictability, safety, and efficacy in the treatment of myopia and myopic astigmatism. The astigmatism correction was effective, but the results suggest that subjective astigmatism of less than 1.0 D need not be treated with the Summit Apex Plus laser.

The cornea in young myopic adults.

AIMS: To further understand the effect of refractive error on the corneal dimensions and function. METHODS: Corneal curvature, corneal thickness, and axial length measurements were performed, as well as specular microscopy and fluorophotometry, on patients with various refractive statuses. 216 subjects, mean age 22.2 (SD 4.2) years, were examined. Patients with previous contact lens wear history, external eye diseases, as well as previous ocular surgeries, were excluded. RESULTS: The corneas were flatter in eyes with longer axial length (r = -0.22, p = 0.003). Eyes with more myopic spherical equivalent had longer axial length (r = -0.90, p <0.001) as well as less corneal endothelial density (r = 0.20, p = 0.037). Corneal endothelial density decreased in eyes with longer axial length (r = 0.24, p = 0.019); however, it correlated neither with corneal thickness (r = -0.06, p = 0.59) nor with corneal curvature (r = -0.07, p = 0.52). The corneas had a mean corneal thickness of 533 (SD 29) microm and were thinner in more myopic eyes (r = 0.16, p = 0.021). The corneas tended to be thinner in eyes with longer axial length. However, the correlation did not reach statistical significance (r = -0.11, p = 0.14). Besides, there was no significant correlation between the corneal thickness and the corneal curvature (r = -0.13, p = 0.093) and the endothelial permeability (r = 0.042, p = 0.69). The corneas with higher endothelial density had larger corneal transfer coefficient (r = 0.26, p = 0.024) and higher permeability to fluorescein molecules (r = 0.28, p = 0.014). Nevertheless, the corneal endothelial permeability did not correlate significantly with either the axial length (r = -0.18, p = 0.11) or the degree of myopia (r = 0.12, p = 0.26). CONCLUSION: Changes in the anterior segments as the eyeball elongates in myopia progression included flatter corneal curvature, decreased corneal thickness, as well as decreased endothelial density. These factors should be considered in refractive surgery.

Immunohistochemical study of subepithelial haze after phototherapeutic keratectomy.

PURPOSE: Subepithelial haze is a frequent complication and is often the cause of regression after photorefractive keratectomy (PRK). The lack of understanding of this undesirable complication following PRK is in part due to the limited availability of suitable tissues for pathological studies. METHODS: We examined the expression of various extracellular components in the cornea of a 46-year-old man who underwent phototherapeutic keratectomy (PTK) to remove a central corneal scar secondary to trauma. The patient subsequently underwent penetrating keratoplasty. A scar-free region containing an area of slight subepithelial haze adjacent to normal cornea was used for immunohistochemical staining with antibodies directed against cytoskeletal proteins, ie, vimentin, desmin and smooth muscle actin, and the extracellular components, laminin, heparan sulfate, keratan sulfate, and collagen types III, IV, V, and VII. RESULTS: Immunohistochemistry revealed that basal epithelial cells expressed components of basement membrane. The stromal fibroblasts within the haze tissue were labeled by anti-smooth muscle actin antibodies, a characteristic of myofibroblasts, which synthesized and secreted extracellular matrix components that contributed to the formation of the disorganized collagenous matrix and may account for subepithelial haze. CONCLUSIONS: The expression patterns for the cytoskeletal proteins and extracellular components indicated that the formation of subepithelial haze is a process of tissue remodeling, involving both corneal basal epithelial cells and keratocytes during wound repair.

Clinical and specular microscopic manifestations of iridocorneal endothelial syndrome.

PURPOSE: To investigate the correlation between the clinical pictures and the specular microscopic findings in patients with iridocorneal endothelial (ICE) syndrome. METHODS: The records of 15 patients with ICE syndrome who presented at the National Taiwan University Hospital between 1993 and 1996 were examined. The medical history, clinical pictures of the cornea, iris and anterior chamber angle, intraocular pressure, specular microscopic findings, and the correlation between clinical and specular microscopic findings were assessed. RESULTS: Endothelial changes in specular micrographs were found in all the patients, even in those patients with minimal angle involvement by peripheral anterior synechiae. Corneal decompensation resulting in corneal edema and bullae formation was the main cause of visual impairment. Neither ICE grading nor endothelial cell density correlated with corneal edema or intraocular pressure, but they correlated with the angle involvement in ICE syndrome. The intraocular pressure was difficult to control in 8 of these patients, even after treatment with anti-glaucoma agents and trabeculectomy, especially in the patients with Cogan-Reese syndrome. CONCLUSION: Although specular microscopy provides an invaluable method for the diagnosis of ICE syndrome, it is not a reliable tool for predicting prognosis. Close follow-up of intraocular pressure and early detection of glaucoma are important steps to preserve visual functions in patients with ICE syndrome.

Effects of contact lenses on corneal endothelium - a morphological and functional study.

PURPOSE: To study the corneal endothelial morphological changes and endothelial barrier function in contact lens wearers. METHODS: Specular microscopy and anterior segment fluorophotometry were performed on 116 controls (group 1) and 76 daily wear soft contact lens wearers. Group 2 patients (n = 34) had been wearing contact lenses for less than 5 years and group 3 (n = 42) for more than 5 years. The relationship of corneal thickness, endothelial cell density, hexagonal cell percentage, coefficient of variation in cell area, corneal autofluorescence and corneal endothelial permeability to the contact lens wear duration was studied. RESULTS: The average corneal thickness of contact lens wearers did not differ significantly from controls (0.533 +/- 0.031, 0.538 +/- 0.044, 0.532 +/- 0.031 mm for groups 1, 2 and 3, respectively; p = 0.89). However, there was a significant tendency toward corneal thinning with a longer history of contact lens wear (r = -0.31, p = 0.002 in groups 2 and 3). The percentage of hexagonal cells decreased with both increasing hours of contact lens wear per day (r = -0.36, p < 0.001) and the duration of contact lens wear in years (r = -0.33, p < 0.001), but there was no significant change in endothelial cell density in contact lens wearers. The coefficient of variation in cell size correlated more closely with increased hours of contact lens wear per day (r = 0.35, p = 0.002) than with the duration of contact lens wear in years (r = 0.12; p = 0.31). In the functional study, corneal autofluorescence increased in contact lens wearers (5.13 +/- 0.71 ng/ml in group 1, 6.45 +/- 2.03 ng/ml in group 2 and 7.21 +/- 1.51 ng/ml in group 3, respectively, p < 0.001) and the mean endothelial permeability decreased in contact lens wearers (3.89 +/- 0.95 x10(-4)/cm in group 1, 2.71 +/- 0.73 x 10(-4)/cm in group 2 and 2.95 +/- 0.91 x 10(-4)/cm in group 3, respectively, p = 0.003). CONCLUSIONS: Daily wear soft contact lenses caused morphological changes in the corneal endothelium. With an increasing span of contact lens wear, there was a significantly increased variation in cell size, a decreased hexagonal cell percentage, an evident intercellular dark area and rosette formation. The corneal autofluorescence increased and the overall endothelial permeability decreased as a consequence of contact lens wear. Contact lens wear also caused corneal thinning, and the cornea became thinner with increasing duration of contact lens wear.

Changing indications for penetrating keratoplasty in Taiwan from 1987 to 1999.

PURPOSE: To determine the leading indications for penetrating keratoplasty and to identify changing trends in these indications during the past 12 years. METHODS: We retrospectively performed a chart review of the hospital records of all patients undergoing penetrating keratoplasty at the National Taiwan University Hospital during a 12-year period (1987-1999). When possible, the clinical indication was corroborated by the pathologic report. RESULTS: A total of 770 corneal transplants were performed. The leading indications for penetrating keratoplasty. in order of decreasing frequency, were corneal scars (27.9%), regraft (21.0%), acute necrotizing and ulcerative keratitis (17.9%), pseudophakic or aphakic bullous keratopathy (17.6%), Fuchs' dystrophy (4.5%), and keratoconus (2.5%). A trend of increasing frequency of regraft and acute necrotizing and ulcerative keratitis, a decreasing frequency of corneal scar, and an initially decreasing then increasing frequency of pseudophakic and aphakic bullous keratopathy were found during the 12-year study period. Acute necrotizing and ulcerative keratitis was found to be the most frequent indication for regraft. CONCLUSION: In this series, corneal scars, regraft, and acute necrotizing and ulcerative keratitis were the leading indications for penetrating keratoplasty. A changing incidence of pseudophakic and aphakic bullous keratopathy noted during the study period was related to the type of intraocular lens implanted and the method of cataract surgery performed. This study found a comparatively high frequency of acute necrotizing and ulcerative keratitis and an extremely low frequency of keratoconus compared with previous reports.