Remote Sensing Image Dehazing through an Unsupervised Generative Adversarial Network.

The degradation of visual quality in remote sensing images caused by haze presents significant challenges in interpreting and extracting essential information. To effectively mitigate the impact of haze on image quality, we propose an unsupervised generative adversarial network specifically designed for remote sensing image dehazing. This network includes two generators with identical structures and two discriminators with identical structures. One generator is focused on image dehazing, while the other generates images with added haze. The two discriminators are responsible for distinguishing whether an image is real or generated. The generator, employing an encoder-decoder architecture, is designed based on the proposed multi-scale feature-extraction modules and attention modules. The proposed multi-scale feature-extraction module, comprising three distinct branches, aims to extract features with varying receptive fields. Each branch comprises dilated convolutions and attention modules. The proposed attention module includes both channel and spatial attention components. It guides the feature-extraction network to emphasize haze and texture within the remote sensing image. For enhanced generator performance, a multi-scale discriminator is also designed with three branches. Furthermore, an improved loss function is introduced by incorporating color-constancy loss into the conventional loss framework. In comparison to state-of-the-art methods, the proposed approach achieves the highest peak signal-to-noise ratio and structural similarity index metrics. These results convincingly demonstrate the superior performance of the proposed method in effectively removing haze from remote sensing images.

Unsupervised Low-Light Image Enhancement Based on Generative Adversarial Network.

Low-light image enhancement aims to improve the perceptual quality of images captured under low-light conditions. This paper proposes a novel generative adversarial network to enhance low-light image quality. Firstly, it designs a generator consisting of residual modules with hybrid attention modules and parallel dilated convolution modules. The residual module is designed to prevent gradient explosion during training and to avoid feature information loss. The hybrid attention module is designed to make the network pay more attention to useful features. A parallel dilated convolution module is designed to increase the receptive field and capture multi-scale information. Additionally, a skip connection is utilized to fuse shallow features with deep features to extract more effective features. Secondly, a discriminator is designed to improve the discrimination ability. Finally, an improved loss function is proposed by incorporating pixel loss to effectively recover detailed information. The proposed method demonstrates superior performance in enhancing low-light images compared to seven other methods.

Quantitative changes in iris vasculature and blood flow in patients with different refractive errors.

PURPOSE: To evaluate the association between microvascular changes in the iris and refractive errors. METHODS: A cross-sectional case study. Seventy eyes from 70 patients with refractive errors were enrolled. Iris microvasculature was analyzed using optical coherence tomography angiography (OCTA). We divided the iris images into three regions and calculated the vessel area density (VAD) and vessel skeleton density (VSD) of the inner one-third, inner two-thirds, and the entirety of the iris. RESULTS: The VADs and VSDs of the different regions were significantly different. The VAD and VSD of the inner one-third of the iris were higher than those of the other regions. The iris blood vessels were denser near the pupil margin, and blood vessels from the iris root to the pupil edge were radially distributed. The VAD and VSD of patients with mild hyperopia and emmetropia were higher than those of patients with moderate and high myopia. As the spherical equivalent increased, the VAD and VSD of the iris increased. Neither age nor sex contributed to significant differences in VAD and VSD. CONCLUSION: Quantitative changes in iris microvasculature may indicate the development of myopia.

A Weak Selection Stochastic Gradient Matching Pursuit Algorithm.

In the existing stochastic gradient matching pursuit algorithm, the preliminary atomic set includes atoms that do not fully match the original signal. This weakens the reconstruction capability and increases the computational complexity. To solve these two problems, a new method is proposed. Firstly, a weak selection threshold method is proposed to select the atoms that best match the original signal. If the absolute gradient coefficients were greater than the product of the maximum absolute gradient coefficient and the threshold that was set according to the experiments, then we selected the atoms that corresponded to the absolute gradient coefficients as the preliminary atoms. Secondly, if the scale of the current candidate atomic set was equal to the previous support atomic set, then the loop was exited; otherwise, the loop was continued. Finally, before the transition estimation of the original signal was calculated, we determined whether the number of columns of the candidate atomic set was smaller than the number of rows of the measurement matrix. If this condition was satisfied, then the current candidate atomic set could be regarded as the support atomic set and the loop was continued; otherwise, the loop was exited. The simulation results showed that the proposed method has better reconstruction performance than the stochastic gradient algorithms when the original signals were a one-dimensional sparse signal, a two-dimensional image signal, and a low-rank matrix signal.

Defect detection of photovoltaic modules based on improved VarifocalNet.

Detecting and replacing defective photovoltaic modules is essential as they directly impact power generation efficiency. Many current deep learning-based methods for detecting defects in photovoltaic modules focus solely on either detection speed or accuracy, which limits their practical application. To address this issue, an improved VarifocalNet has been proposed to enhance both the detection speed and accuracy of defective photovoltaic modules. Firstly, a new bottleneck module is designed to replace the first bottleneck module of the last stage convolution group in the backbone. This new module includes both standard convolution and dilated convolution, enabling an increase in network depth and receptive field without reducing the output feature map size. This improvement can help to enhance the accuracy of defect detection for photovoltaic modules. Secondly, another bottleneck module is also designed and used to replace the original bottleneck module used in the fourth stage convolution group of the backbone. This new module has smaller parameters than the original bottleneck module, which is useful to improve the defect detection speed of the photovoltaic module. Thirdly, a feature interactor is designed in the detection head to enhance feature expression in the classification branch. This helps improve detection accuracy. Besides, an improved intersection over union is proposed and introduced into the loss function to measure the difference between the predicted and ground truth boxes. This is useful for improving defect detection accuracy. Compared to other methods, the proposed method has the highest detection accuracy. Additionally, it also has a faster detection speed than other methods except for the DDH-YOLOv5 method and the improved YOLOv7 method.

Perception-oriented generative adversarial network for retinal fundus image super-resolution.

Retinal fundus imaging is a crucial diagnostic tool in ophthalmology, enabling the early detection and monitoring of various ocular diseases. However, capturing high-resolution fundus images often presents challenges due to factors such as defocusing and diffraction in the digital imaging process, limited shutter speed, sensor unit density, and random noise in the image sensor or during image transmission. Super-resolution techniques offer a promising solution to overcome these limitations and enhance the visual details in retinal fundus images. Since the retina has rich texture details, the super-resolution images often introduce artifacts into texture details and lose some fine retinal vessel structures. To improve the perceptual quality of the retinal fundus image, a generative adversarial network that consists of a generator and a discriminator is proposed. The proposed generator mainly comprises 23 multi-scale feature extraction blocks, an image segmentation network, and 23 residual-in-residual dense blocks. These components are employed to extract features at different scales, acquire the retinal vessel grayscale image, and extract retinal vascular features, respectively. The generator has two branches that are mainly responsible for extracting global features and vascular features, respectively. The extracted features from the two branches are fused to better restore the super-resolution image. The proposed generator can restore more details and more accurate fine vessel structures in retinal images. The improved discriminator is proposed by introducing our designed attention modules to help the generator yield clearer super-resolution images. Additionally, an artifact loss function is also introduced to enhance the generative adversarial network, enabling more accurate measurement of the disparity between the high-resolution image and the restored image. Experimental results show that the generated images obtained by our proposed method have a better perceptual quality than the state-of-the-art image super-resolution methods.

Nighttime road scene image enhancement based on cycle-consistent generative adversarial network.

During nighttime road scenes, images are often affected by contrast distortion, loss of detailed information, and a significant amount of noise. These factors can negatively impact the accuracy of segmentation and object detection in nighttime road scenes. A cycle-consistent generative adversarial network has been proposed to address this issue to improve the quality of nighttime road scene images. The network includes two generative networks with identical structures and two adversarial networks with identical structures. The generative network comprises an encoder network and a corresponding decoder network. A context feature extraction module is designed as the foundational element of the encoder-decoder network to capture more contextual semantic information with different receptive fields. A receptive field residual module is also designed to increase the receptive field in the encoder network.The illumination attention module is inserted between the encoder and decoder to transfer critical features extracted by the encoder to the decoder. The network also includes a multiscale discriminative network to discriminate better whether the image is a real high-quality or generated image. Additionally, an improved loss function is proposed to enhance the efficacy of image enhancement. Compared to state-of-the-art methods, the proposed approach achieves the highest performance in enhancing nighttime images, making them clearer and more natural.

Effects of Topical 0.05% Cyclosporine A on Dry Eye Symptoms and Parameters Following Small Incision Lenticule Extraction.

PURPOSE: To evaluate the effects of topical 0.05% cyclosporine A on Ocular Surface Disease Index (OSDI) score and ocular surface parameters after small incision lenticule extraction (SMILE) for myopia. METHODS: In this study, 151 patients who underwent SMILE were randomized into the control group (71 eyes) and the 0.05% cyclosporine A group (80 eyes). Both groups received standard treatment during the 1 month after SMILE. Over the next 3 months, The control group continued standard therapy (0.3% sodium hyaluronate) and the 0.05% cyclosporine A group received additional 0.05% cyclosporine A. OSDI total and subscale scores, non-invasive tear break-up time (NIBUT), tear lipid layer thickness (LLT), and tear meniscus height (TMH) were assessed preoperatively and postoperatively. RESULTS: Compared to baseline, the OSDI scores significantly increased in both groups (P < .001). The 0.05% cyclosporine A group exhibited lower OSDI total scores after administering 0.05% cyclosporine A versus the control group (P = .026). At 1 month of follow-up, NIBUT, LLT, and TMH values significantly decreased in both groups compared to baseline (P < .05). The 0.05% cyclosporine A group exhibited higher NIBUT, LLT, and TMH versus the control group, returning to preoperative values after 2 months. Overall, the OSDI total score and NIBUT values during follow-up were not significantly different between the two groups; however, the LLT and TMH values were significantly different between the two groups (P < .001 and .041, respectively) by repeated measures analysis of variance. CONCLUSIONS: Topical 0.05% cyclosporine A was effective in relieving subjective dry eye symptoms and maintaining ocular surface stability in the early postoperative period of SMILE. [J Refract Surg. 2024;40(4):e229-e238.].

Topical anesthesia versus regional anesthesia for cataract surgery: a meta-analysis of randomized controlled trials.

PURPOSE: To examine possible differences in the clinical outcomes of topical anesthesia (TA) and regional anesthesia including retrobulbar anesthesia (RBA) and peribulbar anesthesia (PBA) in phacoemulsification. DESIGN: Systematic review and meta-analysis. PARTICIPANTS: Patients from previously published randomized controlled trials (RCTs) of phacoemulsification under TA and RBA/PBA reporting clinical outcomes. METHODS: A comprehensive literature search was performed according to the Cochrane Collaboration method to identify RCTs that compare TA and RBA/PBA in phacoemulsification. MAIN OUTCOME MEASURES: Primary outcome parameters investigated were pain score during and after surgery, intraoperative difficulties and inadvertent ocular movement, intraoperative necessity to administer additional anesthesia, and patient preference. Secondary outcome parameters investigated were postoperative visual acuity, anesthesia-related complications, intraoperative complications, and severe local or systemic complications. RESULTS: Fifteen studies were identified and analyzed to compare TA (1084 eyes) with RBA/PBA (1121 eyes) in phacoemulsification. Data synthesis showed that intraoperative and postoperative pain perception was significantly higher in the TA group (P < 0.05). The TA group showed more frequent inadvertent ocular movement (P < 0.05) and a greater intraoperative need for supplementary anesthesia (P = 0.03). There was no statistically significant difference between the 2 groups in intraoperative difficulties as assessed by the surgeons (P > 0.05). Patients significantly preferred TA (P < 0.00001). The RBA/PBA group had more frequent anesthesia-related complications, such as chemosis, periorbital hematoma, and subconjunctival hemorrhage (P < 0.05). There was no statistically significant difference in surgery-related complications (P > 0.05). CONCLUSIONS: Compared with RBA/PBA, TA does not provide the same excellent pain relief in cataract surgery; however, it achieves similar surgical outcomes. Topical anesthesia reduces injection-related complications and alleviates patients' fear of injection. The choice of TA is not suitable for patients with a higher initial blood pressure or greater pain perception.

A lightweight deep neural network with higher accuracy.

To improve accuracy of the MobileNet network, a new lightweight deep neural network is designed based on the MobileNetV2 network. Firstly, it modifies the network depth of MobileNetV2 to balance the image resolution, network width and depth to keep the gradient stable, which reduces the generation of gradient vanishing or gradient exploding. Secondly, it proposes an improved Bottleneck module by introducing channel attention mechanism. It assigns different weights for different channels according to the degree of relevance between the object features and channels. Therefore, the network can extract more effective features from a complex background. In the end, a new usage strategy of the improved Bottleneck is proposed. It uses the improved Bottleneck module in the second, fourth and fifth stages of MobileNetV2, and uses the original Bottleneck module in other states. Compared with MobileNetV2, MobileNetV3, ShuffleNetV2, GhostNet and HBONetmethods, the proposed method has the highest classification accuracy on the ImageNet-1K dataset, CIFAR-10 and CIFAR-100. Compared with YOLOV4-Lite methods based on these lightweight network networks, YOLOV4-Lite based on our proposed network also has the highest detection accuracy on the PASCAL VOC07+12 dataset.

Dimensionality Reduction of Single-Cell RNA Sequencing Data by Combining Entropy and Denoising AutoEncoder.

ABSTRACT Single-cell RNA sequencing (scRNA-seq) can present cellular heterogeneity at higher resolution when measuring the gene expression in an individual cell. However, there are still some computational problems in scRNA-seq data, including high dimensionality, high sparseness, and high noise. To solve them, dimensionality reduction is essential as it reduces dimensions and also removes most of the zeros and noise. Therefore, we propose a hybrid dimensionality reduction algorithm for scRNA-seq data by integrating binning-based entropy and a denoising autoencoder, named ScEDA. In ScEDA, a novel binning-based entropy estimation method is performed to select efficient genes, while removing noise. For each gene, binning-based entropy is designed to describe the differences in its expression across all cells, that is, the distribution of expression of each gene in all cells. Genes are regarded as inefficient and removed when they achieve low binning-based entropy. Moreover, by combining Kullback-Leibler (KL) divergence with the autoencoder, the objective function is reconstructed to maximize the similarity in distribution between input data and reconstructed data. Furthermore, by adding Poisson-distributed noise to the original input data, the denoising autoencoder is used to improve robustness. Compared with three other clustering methods, ScEDA provides superior average performance on 16 real scRNA-seq datasets, with obvious enhancement in large-scale datasets.

Quantitative changes in iris and retinal blood flow after femtosecond laser-assisted in situ keratomileusis and small-incision lenticule extraction.

Purpose: To investigate the quantitative changes in iris and retinal blood flow indices after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small-incision lenticule extraction (SMILE). Methods: Seventy-nine patients who underwent FS-LASIK or SMILE were enrolled between July 2020 and September 2020. Participants were followed-up 1 day pre-operatively and 1 week, 1 month, 3 months post-operatively. Optical coherence tomography angiography (OCTA) was used to acquire and quantify the iris and retinal blood flow indices. Results: The iris vessel area density (VAD) and vessel skeleton density (VSD) decreased on post-operative day 1 but recovered on day 7. In both cases, the pupil diameter was positively associated with the post-operative iris blood flow indices (p = 0.0013, p = 0.0002). The retinal VAD and VSD in the superficial and deep capillary plexuses decreased after surgery and failed to recover after 90 days. The SMILE group showed significantly lower iris and retinal blood flow indices than the FS-LASIK group. For both procedures, axial length (p = 0.0345, p = 0.0499), spherical equivalence (p = 0.0063, p = 0.0070), and suction duration (p = 0.0025, p = 0.0130) were negatively correlated with the post-operative VAD and VSD. Conclusions: The SMILE and FS-LASIK procedures induced a short-term decrease in the iris and retinal blood flow indices, although patients finally showed full visual recovery. This phenomenon should be carefully considered, especially in patients prone to anterior segment lesions.

Meta-analysis: clinical outcomes of laser-assisted subepithelial keratectomy and photorefractive keratectomy in myopia.

PURPOSE: To examine possible differences in clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) for myopia. DESIGN: Systematic review and meta-analysis. PARTICIPANTS: Patients from previously reported randomized controlled trials (RCTs) and comparative studies of LASEK and PRK with clinical outcomes. METHODS: A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify RCTs and comparative studies comparing LASEK and PRK for myopia. MAIN OUTCOME MEASURES: Primary outcome parameters included uncorrected visual acuity (UCVA) of 20/20 or better, manifest refractive spherical equivalent (SE) within ± 0.50 diopters (D), final refractive SE, and final UCVA of 20/40 or worse. Secondary outcome parameters included healing time of corneal epithelium, postoperative pain, and corneal haze. RESULTS: Twelve studies were identified and used for comparing PRK (499 eyes) with LASEK (512 eyes) for myopia. There were no significant differences in odds ratio (OR), weighted mean difference (WMD), and standardized mean difference (SMD) in the primary and secondary outcome measures. The final mean refractive SE (WMD, 0.00; 95% confidence interval [CI], -0.08 to 0.07; P = 0.95), manifest refractive SE within ± 0.50 D of the target (OR, 0.90; 95% CI, 0.63-1.29; P = 0.56), patients achieving UCVA of 20/20 or better (OR, 0.86; 95% CI, 0.61-1.20; P = 0.37), final UCVA of 20/40 or worse (OR, 1.26; 95% CI, 0.63-2.51; P = 0.52), re-epithelialization time (WMD, 0.08; 95% CI, -0.44 to 0.59; P = 0.77), and postoperative pain (SMD, 0.26; 95% CI, -0.20 to 0.72; P = 0.27) were analyzed. However, LASEK-treated eyes showed less corneal haze at 1 month after surgery (WMD, 0.25; 95% CI, 0.10-0.39; P = 0.0007) and 3 months after surgery (WMD, 0.14; 95% CI, 0.01-0.26; P = 0.03) compared with PRK. No statistically significant difference was observed between the 2 groups at 6 months after surgery (WMD, 0.14; 95% CI, -0.02 to 0.30; P = 0.08). CONCLUSIONS: In this meta-analysis, LASEK-treated eyes had no significant benefits over PRK-treated ones with regard to clinical outcomes. Less corneal haze was observed in LASEK-treated eyes at 1 to 3 months after surgery.

A Systematic Review and Meta-Analysis of Clinical Outcomes of Intravitreal Anti-VEGF Agent Treatment Immediately after Cataract Surgery for Patients with Diabetic Retinopathy.

AIMS: To examine possible benefits of intravitreal anti-vascular endothelial growth factor (VEGF) agent treatment immediately after cataract surgery for patients with diabetic retinopathy (DR). METHODS: A comprehensive literature search was performed using the Cochrane collaboration methodology to identify randomized controlled trials (RCTs) and comparative studies of cataract surgery with or without anti-VEGF agent treatment for any diabetic retinopathy. Meta-analyses were performed for clinical outcome parameters including changes in macular thickness (MT), best-corrected visual acuity (BCVA), incidence of diabetic retinopathy and maculopathy progression, laser treatment rate, and other complications. RESULTS: Nine RCTs and 3 nonrandomized comparative studies were identified and used for comparing cataract surgery with intravitreal bevacizumab (IVB) or intravitreal ranibizumab (IVR) treatment (338 eyes, intervention group) to cataract surgery alone (329 eyes, control group). Analysis of all data showed that the mean BCVA at 1 week postoperatively had no statistically significant difference in the two groups, but at 1, 3, and 6 months postoperatively, the mean BCVA was statistically significantly better in the anti-VEGF treatment group than that in cataract surgery alone group. Analysis of all data showed that the mean MT was statistically significantly less in the anti-VEGF treatment group at 1 week and 1, 3, and 6 months postoperatively (P=0.05, P=0.006, P=0.0001, and P=0.0001, respectively); but postoperative clinical outcomes were differentiated from the type of anti-VEGF agents, IVB or IVR, and the existing macular edema preoperatively. Intravitreal anti-VEGF agent treatment statistically significantly reduced the incidence of diabetic retinopathy progression and maculopathy progression compared to the control group (P=0.0003, P < 0.00001, respectively). CONCLUSION: IVB or IVR treatment immediately after cataract surgery may represent a safe and effective strategy to prevent postoperative macular thickening or reduce macular edema and result in greater mean improvements in visual acuity for diabetic patients.

Bandage Contact Lens Application Reduces Fibrotic Wound Healing of Flap Margins after FS-LASIK: A Prospective Randomized Clinical Trial.

PURPOSE: To assess the efficacy of applying bandage contact lens (BCL) in reducing the fibrotic healing response of flap margins following femtosecond laser in situ keratomileusis (FS-LASIK). METHODS: In this prospective, randomized, interventional, observer-masked trial, 41 patients (82 eyes) with myopia and/or myopic astigmatism were scheduled to undergo FS-LASIK. After surgery, patients were fitted with a BCL in one eye (BCL eyes, n=41) but not in the contralateral eye (control eyes, n=41), following randomized allocation of the BCL to the left or right eye of each patient. The BCL was left in place overnight and removed the following morning. All eyes subsequently received standardized postoperative treatments. Patients were followed up for 6 months. We evaluated patients' self-reported postoperative symptom scores for pain, photophobia, tearing, and foreign-body sensation. At 6 months after surgery, we examined the corneal flap margin and adjacent regions, and photographed them using slit-lamp biomicroscopy, to subjectively evaluate the wound healing response. RESULTS: Postoperative pain and photophobia were milder in the BCL group than in the control group (P=0.041 and P=0.003, respectively), but patients felt more foreign-body sensation in the eye with a BCL than in the control eye (P=0.001). There was no significant difference in tearing score between BCL eyes and control eyes (P=0.118). Regarding the fibrotic healing response of the flap margin, control eyes showed a wide, bright peripheral circumferential band with a spiculated edge and high reflectivity; conversely, BCL eyes showed a markedly narrower and smoother peripheral circumferential band, with a less spiculated edge and lower reflectivity (P < 0.001). CONCLUSION: Patients felt less discomfort in eyes treated with a BCL after FS-LASIK than in control eyes. BCL-treated eyes also had a less intense wound healing response at the flap margins than control eyes in some of patients. BCLs may merit consideration as a treatment option after FS-LASIK for special patients. This trial is registered with ChiCTR1800016579.

Intravenous glucocorticoids therapy in the treatment of Graves' ophthalmopathy: a systematic review and Meta-analysis.

AIM: To evaluate the benefit and harms of high-dose intravenous glucocorticoids (IVGC) as first-line treatment for Graves' ophthalmopathy (GO). METHODS: A systematic review and Meta-analysis of randomized clinical trials (RCTs) comparing IVGC for the treatment of GO, with placebo or other treatments, were conducted. Electronic databases were searched, and standard methodological guidance of Cochrane Handbook for Systematic Reviews of Interventions was used. The primary outcome was overall response, and secondary outcomes included the improvement and change in clinical activity score (CAS), and adverse events. RESULTS: Ten RCTs were included in the Meta-analysis. Low quality evidence (one trial) showed that participants receiving IVGC achieved significantly higher response compared to participants receiving placebo [risk ratio (RR) 7.50, 95% confidence interval (CI) 1.14 to 49.26]. Moderate quality evidence (four trials) support appreciable benefit of IVGC in response compared with oral glucocorticoids (OGC), with of RR being 1.51 (95%CI 1.25 to 1.83). There was low quality evidence (one trial) compatible with appreciable benefit for IVGC plus orbital radiotherapy in response (RR 1.38, 95%CI 1.07 to 1.79), compared with OGC plus orbital radiotherapy. One IVGC versus rituximab trial provided moderate quality evidence suggesting that participants using IVGC achieved significantly lower response compared to participants using rituximab (RR 0.70, 95%CI 0.50 to 0.98). One IVGC versus mycophenolate mofetil (MMF) trial provided moderate quality evidence suggesting that participants using IVGC achieved significantly lower response compared to participants using MMF (RR 0.74, 95%CI 0.63 to 0.88). Very low quality evidence (one trial) showed that participants with dysthyroid optic neuropathy (DON) receiving IVGC were more likely to achieve response compared to participants receiving orbital decompression (RR 3.33, 95%CI 0.51 to 21.89). CONCLUSION: The current evidence is moderate quality, which is sufficient to support IVGC to be as the first-line treatment for moderate-to-severe GO, and the use of rituximab or MMF to be the second-line treatment instead of IVGC. However, the evidence is very low quality, which is insufficient to support the use of IVGC or orbital decompression as the first-line treatment of DON.

Effect of intraoperative mitomycin-C on healthy corneal endothelium after laser-assisted subepithelial keratectomy.

PURPOSE: To evaluate the effect of mitomycin-C (MMC) on corneal endothelial cells after laser-assisted subepithelial keratectomy (LASEK). SETTING: Department of Ophthalmology, Changzheng Hospital, Shanghai, China. METHODS: One hundred seventy-four eyes of 89 patients who did not previously wear contact lenses were treated with LASEK with intraoperative use of topical MMC 0.02% (15 seconds). Noncontact corneal specular microscopy was performed in all eyes preoperatively and 1, 3, and 6 months after surgery. Preoperative pachymetry and ablation depth were measured in all eyes. Repeated-measures analysis of variance was used to compare the changes in the endothelial central cell density (CCD), coefficient of variation in cell size (CV), and percentage of hexagram cells (HEX) over time. Linear regression analysis was conducted to analyze the correlation between the change in the 3 corneal endothelium indices over time and the ablation depth and residual stroma bed (RSB) thickness. RESULTS: Preoperatively, the mean CCD was 2755 cells/mm(2)+/-373 (SD), the mean CV was 31.45+/-8.26, and the mean HEX was 66.03%+/-25.83%. After LASEK, there were no statistically significant changes in CCD, CV, or HEX (P>.05). Multiple linear regression did not identify ablation depth or RSB thickness as being predictive of a change in CCD, CV, or HEX (P>.05). CONCLUSION: The use of intraoperative topical MMC 0.02% for 15 seconds after LASEK did not affect the corneal endothelium.

Laser-Assisted Subepithelial Keratectomy versus Laser In Situ Keratomileusis in Myopia: A Systematic Review and Meta-Analysis.

This systematic review was to compare the clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK) for myopia. Primary parameters included mean manifest refraction spherical equivalent (MRSE), MRSE within ±0.50 diopters, uncorrected visual acuity (UCVA) ≥20/20, and loss of ≥1 line of best-corrected visual acuity (BCVA). Secondary parameters included flap complications and corneal haze. Twelve clinical controlled trials were identified and used for comparing LASEK (780 eyes) to LASIK (915 eyes). There were no significant differences in visual and refractive outcomes between the two surgeries for low to moderate myopia. The incidence of loss of ≥1 line of BCVA was significantly higher in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The efficacy (MRSE and UCVA) of LASEK appeared to be a significant worsening trend in the long-term followup. Corneal haze was more severe in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The flap-related complications still occurred in LASIK, but the incidence was not significantly higher than that in LASEK. LASEK and LASIK were safe and effective for low to moderate myopia. The advantage of LASEK was the absence of flap-related complications, and such procedure complication may occur in LASIK and affect the visual results. The increased incidence of stromal haze and regression in LASEK significantly affected the visual and refractive results for high myopia.