Qinmei Wang

IntraLase Femtosecond Laser vs Mechanical Microkeratomes in LASIK for Myopia: A Systematic Review and Meta-analysis

PURPOSE To evaluate the safety, efficacy, and predictability of IntraLase (Abbott Medical Optics) femtosecond laser-assisted compared to microkeratome-assisted myopic LASIK. METHODS A comprehensive literature search of Cochrane Library, PubMed, and EMBASE was conducted to identify relevant trials comparing LASIK with IntraLase femtosecond laser to LASIK with microkeratomes for the correction of myopia. Meta-analyses were performed on the primary outcomes (loss of ≥2 lines of corrected distance visual acuity [CDVA], uncorrected distance visual acuity [UDVA] 20/20 or better, manifest refraction spherical equivalent [MRSE] within ±0.50 diopters [D], final refractive SE, and astigmatism), and secondary outcomes (flap thickness predictability, changes in higher order aberrations [HOAs], and complications). RESULTS Fifteen articles describing a total of 3679 eyes were identified. No significant differences were identified between the two groups in regards to a loss of ≥2 lines of CDVA (P=.44), patients achieving UDVA 20/20 or better (P=.24), final UDVA (P=.12), final mean refractive SE (P=.74), final astigmatism (P=.27), or changes in HOAs. The IntraLase group had more patients who were within ±0.50 D of target refraction (P=.05) compared to the microkeratome group, and flap thickness was more predictable in the IntraLase group (P<.0001). The microkeratome group had more epithelial defects (P=.04), whereas the IntraLase group had more cases of diffuse lamellar keratitis (P=.01). CONCLUSIONS According to the available data, LASIK with the IntraLase femtosecond laser offers no significant benefits over LASIK with microkeratomes in regards to safety and efficacy, but has potential advantages in predictability.

Measurement of central corneal thickness by high-resolution Scheimpflug imaging, Fourier-domain optical coherence tomography and ultrasound pachymetry

Purpose:  To compare the repeatability and reproducibility of central corneal thickness (CCT) measurements by high‐resolution (HR) rotating Scheimpflug imaging and Fourier‐domain optical coherence tomography (FD‐OCT). CCT measurements were compared to those determined by ultrasound pachymetry (UP).

A Comparison between Scheimpflug Imaging and Optical Coherence Tomography in Measuring Corneal Thickness

PURPOSE To assess the repeatability and reproducibility of 3 rotating Scheimpflug cameras, the Pentacam (Oculus, Wetzlar, Germany), Sirius (Costruzione Strumenti Oftalmici, Florence, Italy), and Galilei (Ziemer, Biel, Switzerland), and 1 Fourier-domain optical coherence tomography (FD-OCT) system, the RTvue-100 OCT (Optovue Inc., Fremont, CA), in measuring corneal thickness. DESIGN Evaluation of diagnostic test. PARTICIPANTS Sixty-six right eyes of 66 healthy volunteers, whose mean age ± standard deviation (SD) was 35.39±10.06 years (range, 18-55 years). METHODS Corneal thickness measurements obtained by each system included central corneal thickness (CCT), thinnest corneal thickness (TCT), and midperipheral corneal thickness (MPCT), measured at superior, inferior, nasal, and temporal locations at a distance of 1 and 2.5 mm from the corneal apex. In the first session, 3 consecutive measurements were performed by the same operator to assess intraobserver repeatability and by a second operator to assess interobserver reproducibility. Measurements were repeated in the second session scheduled 1 day to 1 week later. The mean values obtained in the 2 sessions by the first operator were used to investigate the intersession reproducibility. MAIN OUTCOME MEASURES Intraobserver repeatability and interobserver and intersession repeatability of corneal thickness measurements, as calculated by means of within-subject SD, test-retest repeatability, coefficient of variation (COV), and intraclass correlation coefficients. RESULTS The precision of CCT, TCT, CT2 mm (midperipheral corneal thickness [MPCT] with a distance of 1 mm from the corneal apex), and CT5 mm (midperipheral corneal thickness [MPCT] with a distance of 2.5 mm from the corneal apex) measurements was high with all 4 systems. The COV was ≤1.16%, 0.94%, and 1.10% for repeatability, interobserver reproducibility, and intersession reproducibility, respectively. The 4 devices offered better interobserver reproducibility than intersession reproducibility for all measurements. The CTsuperior-5 mm (midperipheral corneal thickness [MPCT], measured at superior locations with a distance of 2.5 mm from the corneal apex) measurements showed the poorest repeatability and reproducibility. The Galilei revealed the best precision of CCT, TCT, and CT2 mm measurements. CONCLUSIONS Both Scheimpflug imaging and FD-OCT offer highly repeatable and reproducible measurements of CCT and MPCT. The precision was lower in the midperipheral superior quadrant. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Efficacy Comparison of 16 Interventions for Myopia Control in Children: A Network Meta-analysis

PURPOSE To determine the effectiveness of different interventions to slow down the progression of myopia in children. METHODS We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov from inception to August 2014. We selected randomized controlled trials (RCTs) involving interventions for controlling the progression of myopia in children with a treatment duration of at least 1 year for analysis. MAIN OUTCOME MEASURES The primary outcomes were mean annual change in refraction (diopters/year) and mean annual change in axial length (millimeters/year). RESULTS Thirty RCTs (involving 5422 eyes) were identified. Network meta-analysis showed that in comparison with placebo or single vision spectacle lenses, high-dose atropine (refraction change: 0.68 [0.52-0.84]; axial length change: -0.21 [-0.28 to -0.16]), moderate-dose atropine (refraction change: 0.53 [0.28-0.77]; axial length change: -0.21 [-0.32 to -0.12]), and low-dose atropine (refraction change: 0.53 [0.21-0.85]; axial length change: -0.15 [-0.25 to -0.05]) markedly slowed myopia progression. Pirenzepine (refraction change: 0.29 [0.05-0.52]; axial length change: -0.09 [-0.17 to -0.01]), orthokeratology (axial length change: -0.15 [-0.22 to -0.08]), and peripheral defocus modifying contact lenses (axial length change: -0.11 [-0.20 to -0.03]) showed moderate effects. Progressive addition spectacle lenses (refraction change: 0.14 [0.02-0.26]; axial length change: -0.04 [-0.09 to -0.01]) showed slight effects. CONCLUSIONS This network analysis indicates that a range of interventions can significantly reduce myopia progression when compared with single vision spectacle lenses or placebo. In terms of refraction, atropine, pirenzepine, and progressive addition spectacle lenses were effective. In terms of axial length, atropine, orthokeratology, peripheral defocus modifying contact lenses, pirenzepine, and progressive addition spectacle lenses were effective. The most effective interventions were pharmacologic, that is, muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including orthokeratology and peripheral defocus modifying contact lenses, had moderate effects, whereas specially designed spectacle lenses showed minimal effect.

A Comprehensive Assessment of the Precision and Agreement of Anterior Corneal Power Measurements Obtained Using 8 Different Devices

Purpose To comprehensively assess the precision and agreement of anterior corneal power measurements using 8 different devices. Methods Thirty-five eyes from 35 healthy subjects were included in the prospective study. In the first session, a single examiner performed on each subject randomly measurements with the RC-5000 (Tomey Corp., Japan), KR-8000 (Topcon, Japan), IOLMaster (Carl Zeiss Meditec, Germany), E300 (Medmont International, Australia), Allegro Topolyzer (Wavelight AG, Germany), Vista (EyeSys, TX), Pentacam (Oculus, Germany) and Sirius (CSO, Italy). Measurements were repeated in the second session (1 to 2 weeks later). Repeatability and reproducibility of corneal power measurements were assessed based on the intrasession and intersession within-subject standard deviation (Sw), repeatability (2.77Sw), coefficient of variation (COV), and intraclass correlation coefficient (ICC). Agreement was evaluated by 95% limits of agreement (LoA). Results All devices demonstrated high repeatability and reproducibility of the keratometric values (2.77Sw<0.36D, COV<0.3%, ICC>0.98). Repeated-measures analysis of variance with Bonferroni post test showed statistically significant differences (P<0.01) among mean keratometric values of most instruments; the largest differences were observed between the EyeSys Vista and Medmont E300. Good agreement (i.e., 95%LoA within ±0.5D) was found between most instruments for flat, steep and mean keratometry, except for EyeSys and Medmont. Repeatability and reproducibility of vectors J0 and J45 was good, as the ICCs were higher than 0.9, except J45 of Medmont and Pentacam. For the 95% LoAs of J0 and J45, they were all ≤ ±0.31 among any two paired devices. Conclusions The 8 devices showed excellent repeatability and reproducibility. The results obtained using the RC-5000, KR-8000, IOLMaster, Allegro Topolyzer, Pentacam and Sirius were comparable, suggesting that they could be used interchangeably in most clinical settings. Caution is warranted with the measurements of the EyeSys Vista and Medmont E300, which should not be used interchangeably with other devices due to lower agreement. Trial Registration ClinicalTrials.gov NCT01587287

Aberrant human leucocyte antigen‐G expression and its clinical relevance in hepatocellular carcinoma

The clinical relevance of human leucocyte antigen‐G (HLA‐G) has been postulated in malignancies. Hepatocellular carcinoma (HCC) is a major contributor to cancer incidence and mortality worldwide; however, potential roles of HLA‐G in HCC remain unknown. In the current study, HLA‐G expression in 219 primary HCC lesions and their adjacent non‐tumourous samples was analysed with immunohistochemistry. Correlations among HLA‐G expression and various clinical parameters were evaluated. Meanwhile, functional analysis of transfected cell surface HLA‐G expression on NK cell cytolysis was performed in vitro. HLA‐G expression was observed in 50.2% (110/219) of primary HCC lesions, and undetectable in corresponding adjacent normal liver tissues. HLA‐G expression was found in 37.8%, 41.9% and 71.4% of stage I, II and III HCC lesions, respectively. Data revealed that HLA‐G expression in HCC was strongly correlated to advanced disease stage (I versus II, P= 0.882; I versus III, P= 0.020; II versus III, P= 0.037). HLA‐G expression was also more frequently observed in elder patients (≥median 52 years, 57.5%versus 43.4%, P= 0.004). Meanwhile, plasma soluble HLA‐G in HCC patients was significantly higher than that in normal controls (median, 92.49U/ml versus 9.29U/ml, P= 0.000). Functional assay showed that HLA‐G expression in transfected cells could dramatically decrease the NK cell cytolysis (P= 0.036), which could be markedly restored by the blockade of HLA‐G (P= 0.004) and its receptor ILT2 (P= 0.019). Our finding indicated that HLA‐G expression was strongly correlated to advanced disease stage, and more frequently observed in elder patients. Its relevance to HCC progression might be result from the inhibition of NK cell cytolysis.

A murine model of dry eye induced by an intelligently controlled environmental system.

PURPOSE To establish a novel murine model of dry eye using an intelligently controlled environmental system (ICES). METHODS Thirty BALB/c mice aged 4 to 6 weeks were housed in the ICES in which the relative humidity, airflow, and temperature were maintained at 15.3% +/- 3% (mean +/- SD), 2.1 +/- 0.2 m/s, and 21 degrees to 23 degrees C, respectively, for 42 days. Thirty mice of similar age and housed in a normal environment were controls (relative humidity, 60%-80%; no airflow; temperature, 21 degrees -23 degrees C). The ocular surfaces of the animals in both groups were analyzed before and 3, 7, 14, 28, and 42 days after the experiment for aqueous tear production, corneal barrier function, conjunctival morphology, and goblet cell density. The level of apoptosis on the ocular surface also was assessed using active caspase-3 at 42 days. RESULTS A low-humidity environment was maintained constantly by the ICES. Animals in this environment had decreased aqueous tear production, increased corneal fluorescein staining, and marked thinning and accelerated desquamation of the apical corneal epithelium compared with control eyes. Squamous metaplasia of the conjunctival epithelium with decreased goblet cell density also developed in the animals housed in the ICES. Active caspase-3 was highly expressed on the ocular surfaces of the animals housed in the ICES at 42 days. CONCLUSIONS The biological and morphologic changes of dry eye induced by ICES in mice are similar to those in humans. This dry eye environment appears to upregulate apoptosis on the ocular surface.

Comparison of anterior segment measurements with rotating Scheimpflug photography and partial coherence reflectometry

PURPOSE: To compare central corneal thickness (CCT), anterior chamber depth (ACD), and keratometry (K) readings measured using optical low‐coherence reflectometry (OLCR) biometry and high‐resolution rotating Scheimpflug photography. SETTING: Eye Hospital of Wenzhou Medical College, Wenzhou, China. DESIGN: Comparative case series. METHODS: The CCT, ACD endothelium to lens, ACD epithelium to lens, and K (mean; in flattest meridian; in steepest meridian) were measured 5 times using the LenStar/Biograph OLCR biometer and 3 times with the Pentacam Scheimpflug system in eyes of healthy volunteers. Concordance was evaluated using paired t tests, the Pearson correlation, and Bland‐Altman analyses. RESULTS: The CCT, ACD endothelium to lens, and ACD epithelium to lens measured with the Scheimpflug system were slightly, albeit significantly, higher than with the OLCR biometer (P<.05); the respective 95% limits of agreement (LoA) were −8.2 μm to 15.7 μm, −0.11 to 0.15 mm, and −0.13 to 0.17 mm. However, the Scheimpflug system gave significantly flatter readings for K in the flattest meridian (95% LoA, −0.54 to 0.32 diopters [D]), K in the steepest meridian (95% LoA, −0.63 to 0.45 D), and mean K (95% LoA, −0.53 to 0.33 D) (P<.001). The CCT, ACD, and K readings were all highly correlated between the 2 devices (r >0.95, P<.001). CONCLUSIONS: The CCT and ACD measurements with the OLCR biometer and Scheimpflug system can be used interchangeably in healthy young subjects. However, for K measurements, these devices have wide LoA so may not be interchangeable under certain clinical circumstances. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Scheimpflug–Placido topographer and optical low-coherence reflectometry biometer: Repeatability and agreement

Purpose To assess the repeatability of common measurements with the Sirius Scheimpflug–Placido topographer and Lenstar LS900 optical low‐coherence reflectometry (OLCR) biometer and the limits of agreement (LoA) between the devices. Setting Eye Hospital of Wenzhou Medical College, Wenzhou, China. Design Comparative evaluation of a diagnostic test or technology. Methods One randomly healthy eye of subjects was scanned 3 times with both devices. The parameters assessed were central corneal thickness (CCT), anterior chamber depth (ACD) from the corneal epithelium and from the endothelium, mean keratometry (K), and white‐to‐white (WTW) corneal diameter. The repeatability of scans was calculated using the within‐subject standard deviation after 1‐way analysis of variance was performed. The agreement between devices was assessed using the Bland‐Altman LoA method, which equals the mean difference between devices ± 1.96 × standard deviation of the differences. The mean of 3 scans of each device was used to assess the LoA. Results Forty subjects were evaluated. The repeatability of the Scheimpflug–Placido topographer and OLCR biometer was 3.10 μm and 3.32 μm for CCT, 0.04 mm and 0.05 mm for WTW corneal diameter, and 0.17 D and 0.10 D for mean K, respectively. The repeatability for both devices was 0.02 mm for the ACD from the corneal epithelium and the ACD from the corneal endothelium. On Bland‐Altman LoA analysis, all parameters were within clinically acceptable limits. Conclusion Both devices had excellent repeatability for all parameters assessed. Good LoAs were found between the 2 devices, indicating they can be used interchangeably for the parameters assessed. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Changes in corneal wavefront aberrations in microincision and small-incision cataract surgery

PURPOSE: To study the effect of incision size on the optical quality of the anterior cornea by comparing the changes in corneal wavefront aberrations between microincision cataract surgery (MICS) and small‐incision cataract surgery (SICS). SETTING: Eye Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China. METHODS: This prospective randomized clinical study included 36 eyes having MICS (1.5 mm) and 38 eyes having SICS (3.0 mm). Anterior corneal topography was measured preoperatively and 3 to 6 months postoperatively. The data were used to calculate anterior corneal Zernike aberrations (through the 6th order) for a 6.0 mm central area. RESULTS: In the MICS group, 2 corneal Zernike aberrations (trefoil and tetrafoil) changed significantly from preoperatively to postoperatively (both P<.0001). In the SICS group, in addition to trefoil and tetrafoil, oblique astigmatism (P<.0001), secondary oblique astigmatism (P = .001), and vertical tetrafoil (P = .001) changed significantly. The SICS group had greater changes than the MICS group in oblique astigmatism (P = .0001), oblique trefoil (P = .0035), and vertical tetrafoil (P = .0023). The changes in the SICS group were significantly greater than in the MICS group in the total root mean square (RMS) (P = .007) and higher‐order RMS (P = .023) of corneal wavefront aberrations. CONCLUSIONS: Cataract surgery‐related changes in corneal wavefront aberrations were dependent on incision size. The MICS technique had advantages over the SICS technique in minimizing the effect of the incision size on the optical quality of the cornea.