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Background To explore the possible causes of tomography suspect keratoconus (TSK) marked by Tomography in screening keratoconus in a Chinese cohort, and the reasonable range of corneal horizontal diameter and thickness for decreasing the proportion of TSK. Methods Nested case-control study from a single center prospective cohort. All subjects were selected from the Peking University Third Hospital Ectasia Cornea Disease Cohort Project database, which included myopic patients seeking corneal refractive surgical corrections since 2013. Demographic information, basic eye examination, and auxiliary equipment examination including refraction, IOL-master, Pentacam, Sirius, and Topolyzer were recorded. In this study, all cases were classified into two groups: TSK group and normal control (NC) group, and all of them were followed up at least 2 years. The former is consisted of those whose screening examinations of tomography are abnormal, the latter is those whose screening examinations are normal. All of them have already been followed up at least 2 years without abnormalities after excimer laser corneal refractive surgeries. Unpaired t tests and Chi-square tests were used to compare the differences of indices from the tomography between the two groups. Results Of 183 TSK eyes (109 patients) and 160 NC eyes (83 patients), the mean age is 28.0 and 26.3 years old respectively. The corneal horizontal diameter is 11.5–11.8 mm in TSK group and 11.8–12.0 mm in NC group. The central corneal thickness is nearly 520 μm in the former and 550 μm in the latter. For Sirius, the TSK ratio of indices of SIf and SIb is 41.5 and 39.9% respectively in TSK group. For Pentacam, the TSK ratio of index IHD is 59.0% and “final D” is 72.7%. Conclusions Corneal horizontal diameter and central corneal thickness have great influences on the results of corneal tomography in detecting the suspect keratoconus.

Purpose: To compare the proportion of tomography suspect keratoconus (TSK) defined by Sirius and Pentacam, and to explore the possible causes of the differences between them in a Chinese cohort.Methods: Single center retrospect cohort study. All subjects were selected from the Peking University Third Hospital Ectasia Cornea Disease Cohort Project database, which included myopic patients seeking corneal refractive surgical corrections since the year of 2013. Demographic information, basic eye examination, and auxiliary equipment examination including refraction, IOL-master, Pentacam, Sirius, and Topolyzer were recorded. In this study, all cases which were examined by Sirius and Pentacam respectively and have been followed up at least 2 years without abnormalities after laser corneal refractive surgeries (LASEK, FS-LASIK or SMILE). The composition ratio of TSK from Sirius and Pentacam were compared using Pearson Chi-square tests. Unpaired t tests and Chi-square tests were used to compare the differences of corneal diameter, corneal thickness, and variables of corneal tomographers between the normal eyes and the TSK eyes defined by Sirius and Pentacam separately. Results: To the date of December 31, 2018, total 171 cases (278 eyes) were selected in this study, the mean age is 28.4 years old. Total 167 (167/278, 60.1%) eyes were diagnosed of TSK by Sirius, and 203 (203/278, 73.0%) eyes were diagnosed of TSK by Pentacam (PConclusions: The proportion of TSK eyes diagnosed by Sirius is less than those diagnosed by Pentacam in Chinese. Smaller corneal diameter is liable to be judged as TSK by Pentacam in Chinese compared with Sirius. Thinner corneal thickness is liable to be judged as TSK by Sirius in Chinese compared with Pentacam. The variables of SIf and SIb are the main factors leading to TSK in Sirius, the Dt is more stable in Pentacam using for screening normal Chinese cases.

Background to study the outcomes of topography-guided customized excimer laser subepithelial ablation combined with accelerated CXL for progressive keratoconus. Methods Thirty-one eyes of 30 patients with progressive keratoconus were included in this prospective study. Topography-guided excimer laser ablation without refractive correction was performed. Simultaneous accelerated collagen cross-linking with ultraviolet light of 30 mW/cm2 for 4 min was followed. Uncorrected distance visual acuity (UCVA), manifest refraction, corrected distance visual acuity (CDVA), tomograghy were examined at postoperative 1, 6, and 12 months. Results UDVA improved slightly after surgery (P > 0.05). BSCDVA improved significantly from 0.32 ± 0.20 logMAR to 0.15 ± 0.14 logMAR at postoperative 12 months (P apex), which decreased significantly from 57.23 ± 5.09D to 53.13 ± 4.47D (P P P P Conclusions Topography-guided surface ablation without refractive correction combined with simultaneous accelerated collagen cross-linking provided good stability in refraction and corneal curvature, and also showed significant improvement in BSCDVA, corneal regularity and corneal optical quality.

To explore the possible causes of tomography suspect keratoconus (TSK) marked by Tomography in screening keratoconus in a Chinese cohort, and the reasonable range of corneal horizontal diameter and thickness for decreasing the proportion of TSK.Nested case-control study from a single center prospective cohort. All subjects were selected from the Peking University Third Hospital Ectasia Cornea Disease Cohort Project database, which included myopic patients seeking corneal refractive surgical corrections since 2013. Demographic information, basic eye examination, and auxiliary equipment examination including refraction, IOL-master, Pentacam, Sirius, and Topolyzer were recorded. In this study, all cases were classified into two groups: TSK group and normal control (NC) group, and all of them were followed up at least 2 years. The former is consisted of those whose screening examinations of tomography are abnormal, the latter is those whose screening examinations are normal. All of them have already been followed up at least 2 years without abnormalities after excimer laser corneal refractive surgeries. Unpaired t tests and Chi-square tests were used to compare the differences of indices from the tomography between the two groups.Of 183 TSK eyes (109 patients) and 160 NC eyes (83 patients), the mean age is 28.0 and 26.3 years old respectively. The corneal horizontal diameter is 11.5-11.8 mm in TSK group and 11.8-12.0 mm in NC group. The central corneal thickness is nearly 520 μm in the former and 550 μm in the latter. For Sirius, the TSK ratio of indices of SIf and SIb is 41.5 and 39.9% respectively in TSK group. For Pentacam, the TSK ratio of index IHD is 59.0% and "final D" is 72.7%.Corneal horizontal diameter and central corneal thickness have great influences on the results of corneal tomography in detecting the suspect keratoconus.

PurposeTo evaluate the value of Scheimpflug-based biomechanical analyzer combined with tomography in detecting early keratoconus by distinguishing normal eyes from frank keratoconus (KC) and forme frusta keratoconus (FFKC) eyes in Chinese patients. MethodsThis study included 31 bilateral frank keratoconus patients, 27 unilateral clinical manifest keratoconus patients with very asymmetric eyes, and 79 control subjects with normal corneas. Corneal morphological and biomechanical parameters were measured using the Pentacam HR and Corvis ST (OCULUS, Wetzlar, Germany). The diagnostic capacity of computed parameters reflecting corneal biomechanical and morphological traits [including Belin-Ambrósio deviation index (BAD_D), Corvis biomechanical index (CBI) and tomographic and biomechanical index (TBI)] was determined using receiver operating characteristic (ROC) curves and compared by DeLong test. Additionally, the area under the curve (AUC), the best cutoff values, and Youden index for each parameter were reported. The novel corneal stiffness parameter (Stress-Strain Index or SSI) was also compared between KC, FFKC and normal eyes.ResultsEvery morphological and biomechanical index analyzed in this study was significantly different between KC, FFKC and normal eyes (p=0.000). TBI was most valuable for detecting subclinical keratoconus (FFKC eyes) with an AUC of 0.928 (P=0.000), and any forms of corneal ectasia (FFKC and frank KC eyes) with an AUC of 0.966 (P=0.000). The sensitivity and specificity of TBI for detecting FFKC was 97.5% and 77.8%, for detecting any KC was 97.5% and 89.7%, with a cut-off value of 0.375. Morphological index BAD_D and biomechanical index CBI were also very useful in distinguishing any KC eyes from normal eyes with an AUC of 0.965 and 0.934, respectively. SSI was significantly different between KC, FFKC and normal eyes (P=0.000), indicating an independent decrease in corneal stiffness in KC eyes.Conclusion Combination of Scheimpflug-based biomechanical analyzer and tomography could increase the accuracy of detecting early keratoconus in Chinese patients. TBI was the most valuable index for detecting subclinical keratoconus with high sensitivity and specificity. Evaluation of corneal biomechanical property in refractive surgery candidates is helpful to recognize potential keratoconic eyes and increase surgical safety.

AIM: To compare clinical results between toric and spherical periphery design orthokeratology (ortho-k) in myopic children with moderate-to-high corneal astigmatism. METHODS: This retrospective study enrolled 62 eyes of 62 subjects using toric ortho-k lenses. These subjects were assigned to the toric group. Based on the one-to-one match principle (same age, proximate spherical equivalence and corneal astigmatism), 62 eyes of 62 subjects were enrolled and included in the spherical group. At one-year follow-up visit, visual acuity, corneal astigmatism, treatment zone decentration, axial elongation and adverse reaction were compared between these two groups. RESULTS: At the one-year visit, corneal astigmatism was significantly lower in the toric group (1.22±0.76 D) than in the spherical group (2.05±0.85 D) (P=0.012). The mean magnitude of the treatment zone decentration was 0.62±0.42 mm in the toric group and 1.07±0.40 mm in the spherical group (P=0.004). Axial elongation was significantly slower in the toric group (0.04±0.13 mm) than in the spherical group (0.09±0.13 mm) (P=0.001). The one-year axial elongation was significantly correlated with initial age (r=-0.487, P

Background To compare the incidence of rainbow glare (RG) after femtosecond laser assisted-LASIK (FS-LASIK) using the upgraded FS200 femtosecond laser with different flap cut parameter settings. Methods A consecutive series of 129 patients (255 eyes) who underwent FS-LASIK for correcting myopia and/or astigmatism using upgraded WaveLight FS200 femtosecond laser with the original settings was included in group A. Another consecutive series of 129 patients (255 eyes) who underwent FS-LASIK using upgraded WaveLight FS200 femtosecond laser with flap cut parameter settings changed (decreased pulse energy, spot and line separation) was included in group B. The incidence and fading time of RG, confocal microscopic image and postoperative clinical results were compared between the two groups. Results There were no differences between the two groups in age, baseline refraction, excimer laser ablation depth, postoperative uncorrected visual acuity and refraction. The incidence rate of RG in group A (35/255, 13.73%) was significantly higher than that in group B (4/255, 1.57%) (P 0.05).The confocal microscopic images showed wider laser spot spacing in group A than group B. The incidence of RG was significantly correlated with age and grouping (P

PURPOSE: To evaluate and compare the thickness and the morphology of femtosecond and mechanical microkeratome LASIK flaps using anterior segment optical coherence tomography (AS-OCT). METHODS: Bilateral LASIK was performed in 132 eyes from 61 myopic patients. Flaps were created in 72 eyes using the WaveLight FS200 femtosecond laser (Wave-Light GmbH, Erlangen, Germany) and in 50 eyes using the Moria microkeratome (Moria SA, Antony, France). AS-OCT was used 1 week postoperatively to evaluate the thickness of 17 points across each flap, which were 0, 2, and 3.5 mm to the corneal vertex on the horizontal, vertical, 45°, and 135° meridians. RESULTS: The mean central flap thickness was 105.53 ± 5.86 μ m in the WaveLight group and 132.96 ± 13.91 μ m in the Moria group ( P < .001). The difference between the achieved and the intended flap thickness (accuracy) was 6.17 ± 3.98 and 23.60 ± 12.64 μm, respectively ( P < .001). The standard deviation within individual flap (uniformity) was smaller in the WaveLight group. The symmetry and regularity were also better in the WaveLight group. Flap morphology showed a more regular planar shape in the WaveLight group and a meniscus shape in the Moria group. CONCLUSIONS: AS-OCT showed that the flaps created by the WaveLight femtosecond laser were more accurate, reproducible, and uniform than those created by the Moria microkeratome. [ J Refract Surg. 2013;29(5):320–324.]

Purpose: To analyze the accuracy and consistency of corneal flap thickness created in myopic LASIK using the Moria One Use-Plus microkeratome compared with the Moria M2 Single Use 90- μ m microkeratome. Methods: Bilateral LASIK was performed in 68 myopic patients. Flaps were created using the One Use-Plus microkeratome in 82 eyes (41 patients) and the M2 90- μ m microkeratome in 54 eyes (27 patients). Flap complications and visual outcomes were evaluated. Horizontal “High Res. Corneal” scan pattern of anterior segment optical coherence tomography (AS-OCT) was applied to measure flap thickness at five locations (0, ±2, and ±3.5 mm from the corneal vertex) on the first postoperative day. Results: No significant differences were noted in flap complications and visual outcomes between groups. The central flap thickness was dramatically thinner in the One Use-Plus group (114.7±10.1 μ m and 109.4±11.0 μ m for right and left eyes, respectively) than in the M2 group (155.6±14.8 μ m and 151.6±12.5 μ m for right and left eyes, respectively) ( P P Conclusions: The One Use-Plus and M2 microkeratomes have similar safety and efficacy. The flap created by the One Use-Plus was much thinner than the flap created with the M2; however, the One Use-Plus can not realize a fully planar-shaped flap.

In this paper, we consider skyline queries in a mobile and distributed environment, where data objects are distributed in some sites (database servers) which are interconnected through a high-speed wired network, and queries are issued by mobile units (laptop, cell phone, etc.) which access the data objects of database servers by wireless channels. The inherent properties of mobile computing environment such as mobility, limited wireless bandwidth, frequent disconnection, make skyline queries more complicated. We show how to efficiently perform distributed skyline queries in a mobile environment and propose a skyline query processing approach, called efficient distributed skyline based on mobile computing (EDS-MC). In EDS-MC, a distributed skyline query is decomposed into five processing phases and each phase is elaborately designed in order to reduce the network communication, network delay and query response time. We conduct extensive experiments in a simulated mobile database system, and the experimental results demonstrate the superiority of EDS-MC over other skyline query processing techniques on mobile computing.

To investigate the risk factors of inadvertent cornea stromal dissection during mechanical epikeratome separation of the corneal epithelium using a Moria Epi-keratome and to explore the best procedure for the treatment of this complication.We retrospectively reviewed inadvertent stromal dissections in central or peri-central areas of the cornea during mechanical epi-keratome separation of the corneal epithelium from a series of 708 eyes (355 patients) who received myopic Epi-laser-assisted in situ keratomileusis (Epi-LASIK) procedures during the past five years. The best spectacle corrected visual acuities (BCVA) and topographies at the final follow-up after the last procedures were compared.From the total of treated eyes, 4 eyes of 4 patients (0.56%) suffered inadvertent stromal dissection. In two of them, an excimer laser ablation under the flaps was performed immediately. One patient was treated with LASIK 6 month after the first procedure and another one received an excimer laser photo-therapeutic keratectomy (PTK) removing the corneal epithelium and photorefractive keratectomy (PRK) for refractive correction 1 month after Epi-LASIK. Postoperatively, BCVA lost one line in one eye which received immediate excimer laser ablation under complicated flap. Topography demonstrated irregularity corresponding to the site of stromal dissection. Two eyes (one received immediate excimer laser ablation and another received LASIK 6 month after stromal dissection) recovered to the pre-Epi-LASIK BCVA. One eye that received PTK and PRK 1 month after Epi-LASIK obtained an increase of one line in BCVA. Topography in all three eyes showed regular patterns in the middle of the cornea.Stromal dissection during mechanical separation of the corneal epithelium with Moria Epi-K epikeratome is a potential complication of Epi-LASIK. One month postoperative PTK and PRK turned out to be the option of proper management for good recovery without severe visual impairment.

Until now, in the territory of surgical methods, excimer laser refractive surgeries have being the main stream for correcting the ametropic eyes. The main cause of iatrogenic corneal ectasia and keratoconus, one of the most severe complications of corneal refractive surgeries, is the destruction of corneal biomechanics. Keeping corneal biomechanical integrality is the basis for long term effectiveness, stableness, and safety of the corneal refractive surgeries. The reasonable indication and surgical method decision, perioperative medical cares play very important roles in preventing those severe complications.

PURPOSE: To compare tear cytokines and clinical outcomes between off-flap and on-flap epi-LASIK eyes and explore the possible mechanism for the clinical differences. METHODS: This double-masked, randomized study enrolled 18 myopic patients who underwent off-flap epi-LASIK with mitomycin C (MMC) in 1 eye and on-flap epi-LASIK with MMC in the contralateral eye. Tears were collected from each eye preoperatively and 2 hours, 1 day, and 5 days postoperatively. Concentrations of multiple tear cytokines were measured by a multiplex immunobead assay. Uncorrected distance visual acuity (UDVA), refraction, haze scores, pain scores, and percentage of corneal epithelial healing were evaluated. RESULTS: Compared with the on-flap group, the off-flap group had outcomes of better UDVA and higher percentages of epithelial healing at 5 days after surgery ( P P =.049). Preoperatively, no significant differences were noted in the release rate of all tear cytokines between groups. At 2 hours postoperatively, the release rate of tear basic fibroblast growth factor (bFGF), platelet-derived growth factor-BB (PDGF-BB), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) in the off-flap group were significantly lower than those in the on-flap group ( P =.011, .017, .048, and .041, respectively). CONCLUSIONS: Off-flap epi-LASIK with MMC offers faster corneal epithelial healing and visual recovery, and temporary less haze than on-flap epi-LASIK with MMC. The lower tear levels of bFGF, PDGF-BB, IL-8, and TNF-α in the offflap group 2 hours after surgery may suggest a possible mechanism for the clinical differences.

To explore the temporal expression of retinal-choroidal transforming growth factor-beta2 (TGF-beta2) in form-deprived myopia (FDM) chick eyes and study the effect of an inhibitor (disulfiram, DSF) of retinoid acid (RA) synthesis on refractive development and the expression of TGF-beta2.Ninety new hatched white leghorn chicks were divided randomly and equally into 3 groups: unilateral occluded with frosted goggles (Group A); unilateral intravitreal injection of 4 mmol of the non-specific aldehydedehydrogenase inhibitor disulfiram with further treatment with goggles (Group B); unilateral intravitreal injections of 4 mmol of disulfiram without further treatment with goggles (Group C). Refraction and axial length were measured on 1, 7 and 14 days after treatment. Expression levels of TGF-beta2 and TGF-beta2 mRNA in the retinal-choroid layer were analyzed by immunohistochemistry and real-time RT-PCR.In Group A, the form-deprived eyes made by goggles developed myopia (P0.05 on day 1, P0.01 on days 7 and 14, compared with the contralateral eyes) with a lengthening of the axial length (P0.01 on days 7 and 14, compared with the contralateral eyes), as well as a lower level of TGF-beta2 expression (P0.01 on days 7 and 14, compared with the contralateral eyes). In Groups B and C, there was no statistically significant difference in refraction and axial length between treated and contralateral eyes (P0.05) with TGF-beta2 mRNA level growing on day 7 and decreased on day 14 in group B and decreased on day 1, increased on days 7 and 14 in Group C (P0.01, compared with the contralateral eyes). Immunohistochemistry showed that the expression of TGF-beta2 was mainly changed in the outer part of photoreceptor layer and retinal pigment epithelium (RPE) layer.TGF-beta2 mRNA level decreased in FDM eyes. Disulfiram can up-regulate the level of TGF-beta2 mRNA expression in the posterior retinal-choroid, and inhibit the elongation of axial length and refractive error made by frosted goggles as well. Disulfiram which inhibits the synthesis of retinoid acid may suppress deprivation myopia by up-regulating the expression level of TGF-beta2 mRNA.

To compare the visual and refractive outcomes of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) in the treatment of severe myopia.LASEK and LASIK were respectively performed on 165 eyes of 100 patients with super high myopia by using the Allegretto Wavelight-Wave 1,007 excimer laser, of which 10(6) eyes (62 patients) were treated with LASEK and 59 eyes (38 patients) with LASIK. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), remaining refractive error, corneal haze and complications were followed up in both groups for 12 months.At the end of 6 months and 12 months no significant statistic difference between LASEK and LASIK group in the clinical outcomes of refractive corrections (mean spherical equivalent, MSE). At the end of 1 week and 1 month postoperatively, UCVA in the LASIK eyes was better than in LASEK eyes. At the end of 3, 6, 12 months, it was almost the same in these two groups. The percentage of eyes with UCVA better than 1.0 (47.8% in LASEK, 52.5% in LASIK) was higher in LASEK group. There was no significant difference between the two groups in the percentage of eyes losing one or more lines of BSCVA in Snellen visual acuity chart. At the end of 12 months, the mean SE was within +/-0.5D of emmetropia in 9 eyes (13.2%) in the LASEK group and 11 eyes (18.6%) in the LASIK group and within +/-1.0D of emmetropia in 36 eyes (52.9%) in the LASEK group and 28 eyes (47.5%) in the LASIK group, respectively, the between-group differences were not statistically significant (P0.05). There were more complaints of postoperative pain and discomfort after LASEK procedure. No severe vision threatening complications in these two groups were found.Both LASIK and LASEK are safe and effective in treating eyes with severe myopia.

To study the higher order aberrations of emmetropic and ametropic eyes with wavefront aberrometer.Forty of cases 77 emmetropic and ametropic eyes were measured with an aberrometer based on Tscherning's principle with the pupils dilated. The Zernike coefficients and root mean square values of wavefront aberrations up to the 6th order were recorded and statistically analyzed.The C06, C07, C08, C12, C13, C14, C24, C26, and C27 were significantly different from zero under 7 mm pupil size and the C06, C10, C12, C23, and C24 were significantly different from zero under 4 mm pupil size. There was no significant difference of higher order wavefront aberrations between emmetropic and ametropic eyes. Comparing the age of 40 years or less with the age over 40 years, there were significant differences in RMS3 between the two under 7 mm pupil size, and statistical differences in RMS6 and RMSh between the two under 4 mm pupil size.There are certain higher order wavefront aberrations in the normal human eyes, especially with the pupils dilated. No differences are found in higher order aberrations between emmetropic and ametropic eyes. The higher order aberrations of the age over 40 years are more than those of the age of 40 years or younger.

To investigate the expression of NF-kappa B following retinal ischemia and reperfusion injury in mice.Retinal ischemia was induced by elevation of intraocular pressure. Retinal degeneration and atrophy were quantified by an image analysis system. Immunohistochemistry using p65 monoclonal antibody was performed on the retina and co-related with TUNEL labeling.Inner retinal thickness was increased in the initial 24 hours following retinal ischemia and was ascribed to tissue edema, but was significantly decreased by 168 hours after reperfusion. Six hours after retinal ischemia, p65 immunoreactivity was increased in the ganglion cell and the inner nuclear layers, reached a peak at 24 hours, and was parallel to TUNEL labeling. Double labeling with p65 and TUNEL showed partial co-localization of p65 and TUNEL labeling, predominantly in the inner nuclear layer.Activation of NF-kappa B appears to play an important role in retinal degeneration following retinal ischemia and reperfusion injury. The pro- and anti-apoptotic effects of NF-kappa B after retinal ischemia are being further investigated.

Nuclear factor-kappaB (NF-kappaB) is a universal transcription factor and has previously been demonstrated to play an important role in CNS injury. This study investigated the expression of NF-kappaB in the inner layers of the retina in mice after retinal ischemia and reperfusion injury. Retinal ischemia was induced by elevation of intraocular pressure to 120 mmHg for 60 min. To evaluate inner retinal degeneration, the inner retinal thickness was quantified with an image-analysis system. The inner retinal thickness increased in the initial 24 hr after retinal ischemia and was ascribed to tissue edema but was significantly decreased in the ensuing 7 days. Immunohistochemistry using NF-kappaB p65 monoclonal antibody was performed on the retina and was corelated with TUNEL labeling. Six hours after retinal ischemia, nuclear p65 immunoreactivity was increased in the inner nuclear and ganglion cell layers and reached a peak at 24 hr. The increased NF-kappaB p65 immunolabeling was parallel to the TUNEL labeling. Double labeling with p65 and TUNEL showed partial colocalization of p65 and TUNEL labeling in the scattered cells of the inner nuclear and ganglion cell layers. However, several p65-positive cells were TUNEL negative, suggesting that these cells might have survived the injury. The NF-kappaB p65 immunoreactivity was associated with retinal degeneration following retinal ischemia and reperfusion injury.