Does the introduction of streamlight decrease refractive surgery operating time?

PURPOSE: The aim of the study was to analyze the time-savings associated with introduction of Streamlight™ (Alcon Laboratories, Fort Worth, TX, USA) transepithelial photorefractive keratectomy (PRK) in surface corneal ablations. METHODS: All refractive surgeries were performed using the Alcon WaveLight® EX500 at the ArtLife Clinic, Gdansk, Poland. The study included patients treated for refractive errors with transepithelial PRK between April 2019 and October 2021, who were matched with patients treated with alcohol-assisted PRK during the same period. Only results for the left eye were analyzed. RESULTS: One-hundred-five patients underwent transepithelial PRK (age 33.42 ± 8.67 years) and were matched with 105 patients that underwent alcohol-assisted PRK (age 33.05 ± 10.16 years; p = 0.11). The mean preoperative spherical equivalent refraction was - 2.04 ± 2.28 D, and - 1.9 ± 1.71 D for the transepithelial and alcohol-assisted PRK group, respectively (p = 0.20). The total surgery time was non-significantly shorter in transepithelial PRK (349.46 ± 47.83 s) than in alcohol-assisted PRK (354.93 ± 137.63 s; p = 0.7); however, the variance of surgical time was significantly lower in transepithelial PRK (p < 0.001). The laser treatment duration was greater in transepithelial PRK (41.78 ± 17.2 s) than in alcohol-assisted PRK (8.48 ± 6.12 s; p < 0.001), and so was the number of breaks during the laser treatment (0.95 ± 0.63 vs. 0.53 ± 0.88, respectively; p < 0.001). CONCLUSION: The introduction of transepithelial PRK did not bring significant time-associated savings into the refractive surgery suite.

New forays into measurement of ocular biomechanics.

PURPOSE OF REVIEW: The field of corneal biomechanics has rapidly progressed in recent years, reflecting technological advances and an increased understanding of the clinical significance of measuring these properties. This review will evaluate in-vivo biomechanical properties obtained by current technologies and compare them regarding their relevance to established biomechanical properties obtained by gold-standard ex-vivo techniques normally conducted on elastic materials. RECENT FINDINGS: Several new technologies have appeared in recent years, including vibrational optical coherence tomography (VOCT) and the corneal indentation device (CID). These techniques provide promising new opportunities for minimally invasive and accurate measurements of corneal viscoelastic properties. SUMMARY: Alterations in corneal biomechanics are known to occur in several corneal degenerative diseases and after refractive surgical procedures. The measurement of corneal biomechanical properties has the capability to diagnose early disease and monitor corneal disease progression. Several new technologies have emerged in recent years, allowing for more accurate and less invasive measurements of corneal biomechanical properties, most notably the elastic modulus.

Magnitude and Determinants of Awareness Regarding Refractive Surgeries Among Saudi Adults.

Objectives: This study aimed to present the magnitude and determinants of awareness about refractive surgery among the adult Saudi population and recommend knowledge improvement. Methods: This web-based cross-sectional study was conducted between June 2020 and May 2021 across various regions of Saudi Arabia on the adult Saudi population. A total of 11 close-ended questions regarding indication, contraindication, preparation and surgery procedures were asked. The awareness scores were grouped as 'good' (≥6) or 'poor' (≤5). Demographic and ocular parameters were associated with the outcomes. Results: Of the 6,746 participants, 6,580 (response rate = 97.5%) completed the survey. The participation of younger women and older men was greater than their proportions in the population, while older women participated less than their proportion. Good awareness about refractive surgery was noted in 1,165 (17.7%; 95% confidence interval: 16.2-18.0) participants. Women (P <0.001), the 18-29 age group (P <0.001), residents of the central region of Saudi Arabia (P <0.001), health professionals (P <0.001), health sector students (P = 0.0004), people with myopia (P <0.001) and history of refractive surgery (P <0.001) were associated with good awareness. Women (adjusted odds ratio [AOR] = 1.5; P <0.001), health sector students (AOR = 1.57; P <0.001), and residents in the central region (AOR = 1.27; P <0.001) were independent predictors of awareness. Knowledge about contraindications for surgery was good in more than one-third of the participants. Of the 535 participants who underwent surgery in the past, 452 (84.5%) were satisfied with their outcomes. Conclusion: Awareness of refractive surgeries is low in the adult Saudi population. Targeted counseling is recommended to improve the knowledge and acceptance of refractive surgery.

The Effects of Whole-Corneal and Whole-Eye Higher Order Aberrations on the Discrepancy Between Refractive and Corneal Astigmatism in Otherwise Healthy Candidates for Refractive Surgery.

PURPOSE: To evaluate the effect of different whole-corneal and whole-eye higher order aberrations (HOAs) on levels of axis discrepancy. METHODS: This was a retrospective study including healthy candidates for refractive surgery, with one eye being randomly selected. A total of 360 eyes were included. Whole-corneal and whole-eye HOAs were measured twice with a Pentacam AXL Wave (Oculus Optikgeräte GmbH), and subjective manifest refraction was obtained. Axis discrepancy was defined as the absolute difference between Total Corneal Refractive Power flat keratometry axis and manifest refractive axis. Two multiple linear regression models that sought to explore the effect of HOAs in predicting axis discrepancy while adjusting for corneal and refractive confounders were built. RESULTS: Mean age was 29.1 ± 5.8 years and 63.9% of the patients were women. Mean manifest sphere and cylinder were -3.09 ± 2.36 and -1.45 ± 1.37 diopters (D), respectively. Mean cylinder axis discrepancy was 14.4 ± 14.5°. On multiple linear regression, the only variables significantly associated with axis discrepancy were corneal cylinder and corneal lower order aberrations [F(5,339) = 29.746; P < .001; adjusted R2 = 0.295]. Lower levels of corneal cylinder are by far the main contributor to astigmatism axis mismatch (ß = -1.164). There was not a single HOA, either corneal or ocular, that significantly loaded into any models. CONCLUSIONS: Astigmatism axis mismatch decreases rapidly with increasing levels of corneal astigmatism. Corneal and whole-eye HOAs have no role in astigmatism axis mismatch in healthy candidates for refractive surgery. [J Refract Surg. 2024;40(2):e89-e97.].

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management.

ABSTRACT: Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Choice of refractive surgery types for myopia assisted by machine learning based on doctors' surgical selection data.

In recent years, corneal refractive surgery has been widely used in clinics as an effective means to restore vision and improve the quality of life. When choosing myopia-refractive surgery, it is necessary to comprehensively consider the differences in equipment and technology as well as the specificity of individual patients, which heavily depend on the experience of ophthalmologists. In our study, we took advantage of machine learning to learn about the experience of ophthalmologists in decision-making and assist them in the choice of corneal refractive surgery in a new case. Our study was based on the clinical data of 7,081 patients who underwent corneal refractive surgery between 2000 and 2017 at the Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences. Due to the long data period, there were data losses and errors in this dataset. First, we cleaned the data and deleted the samples of key data loss. Then, patients were divided into three groups according to the type of surgery, after which we used SMOTE technology to eliminate imbalance between groups. Six statistical machine learning models, including NBM, RF, AdaBoost, XGBoost, BP neural network, and DBN were selected, and a ten-fold cross-validation and grid search were used to determine the optimal hyperparameters for better performance. When tested on the dataset, the multi-class RF model showed the best performance, with agreement with ophthalmologist decisions as high as 0.8775 and Macro F1 as high as 0.8019. Furthermore, the results of the feature importance analysis based on the SHAP technique were consistent with an ophthalmologist's practical experience. Our research will assist ophthalmologists in choosing appropriate types of refractive surgery and will have beneficial clinical effects.

[Characterization of rabbit corneal biomechanical properties after corneal refractive surgery based on rapid loading-unloading uniaxial tensile test].

In order to understand how the biomechanical properties of rabbit cornea change over time after corneal ablation, 21 healthy adult rabbits were used in this study, with the left eye as experimental side and the right eye as the control side. Firstly, a lamellar knife was used to remove a portion of the anterior corneal surface tissue (30%~50% of the original corneal thickness) from the left eye of each rabbit, as an animal model simulating corneal refractive surgery. Secondly, postoperative experimental rabbits were kept for one, three, or six months until being euthanized. Strip specimens were produced using their corneas in vitro to perform a uniaxial tensile test with an average loading-unloading rate of approximately 0.16 mm/s. Finally, the visco-hyperelastic material constitutive model was used to fit the data. The results showed that there was a significant difference in the viscoelastic parameters of the corneas between the experimental and the control eyes at the first and third postoperative months. There was a difference in tangential modulus between the experimental and the control eyes at strain levels of 0.02 and 0.05 at the third postoperative month. There was no significant difference in biomechanical parameters between the experimental and the control eyes at the sixth postoperative month. These results indicate that compared with the control eyes, the biomechanical properties of the experimental eyes vary over postoperative time. At the third postoperative month, the ratio of corneal tangential modulus between the experimental and the control eyes significantly increased, and then decreased. This work lays a preliminary foundation for understanding the biomechanical properties of the cornea after corneal refractive surgery based on rapid testing data obtained clinically.

Perioperative intense pulsed light to prevent and improve symptoms of post-laser corneal refractive surgery dry eye. A randomized clinical trial.

PURPOSE: To evaluate the efficacy of perioperative IPL therapy in preventing postoperative ocular surface disorders in patients undergoing corneal laser refractive surgery. DESIGN: randomized, controlled, clinical trial with triple-blinding. METHODS: Setting: Vissum Miranza - Alicante; Study population: 61 patients randomized in two groups: 31 study patients (perioperative IPL + laser refractive surgery) and 30 control patients (perioperative placebo + laser refractive surgery). Follow-up was conducted over a 6-month period; Intervention: Each participants underwent three IPL sessions with a two-week interval between each session (pre-surgery, post-surgery week-one, and post-surgery week-three). For controls, placebo was administered following the same protocol. MAIN OUTCOMES MEASURES: visual outcomes and refraction, slit-lamp examination, corneal topography, visual analogue scale questionnaire and Oculus Keratograph 5 M including tear meniscus height, non-invasive tear break- up time, ocular redness, infrared meibography and Ocular Surface Disease Index (OSDI) questionnaire. RESULTS: 61 randomized eyes were included. No significant differences were observed in terms of uncorrected and corrected distance visual acuity (UDVA, CDVA), refractive error or corneal aberrations. A statistically significant improvement in OSDI score (change -8.47, p = 0.043), tear meniscus (change 0.05 mm, p = 0.004) and Meibography (change -0.42, p = 0.012) was observed at the third postoperative month in the study group. Additionally, at the sixth postoperative month, there were statistically significant improvements in tear meniscus (change 0.06 mm, p = 0.018), tear break-up-time (change 1.68 s, p = 0.039) and Meibography (change -0.37, p = 0.030). CONCLUSIONS: Results suggest that perioperative IPL therapy applied to laser corneal refractive surgery improves objective and subjective ocular surface parameters over non-IPL-treated control patients and early postoperative dry eye symptoms.

MTIE-Net: Multi-technology fusion of low-light image enhancement network.

Images obtained in low-light scenes are often accompanied by problems such as low visibility, blurred details, and color distortion, enhancing them can effectively improve the visual effect and provide favorable conditions for advanced visual tasks. In this study, we propose a Multi-Technology Fusion of Low-light Image Enhancement Network (MTIE-Net) that modularizes the enhancement task. MTIE-Net consists of a residual dense decomposition network (RDD-Net) based on Retinex theory, an encoder-decoder denoising network (EDD-Net), and a parallel mixed attention-based self-calibrated illumination enhancement network (PCE-Net). The low-light image is first decomposed by RDD-Net into a lighting map and reflectance map; EDD-Net is used to process noise in the reflectance map; Finally, the lighting map is fused with the denoised reflectance map as an input to PCE-Net, using the Fourier transform for illumination enhancement and detail recovery in the frequency domain. Numerous experimental results show that MTIE-Net outperforms the comparison methods in terms of image visual quality enhancement improvement, denoising, and detail recovery. The application in nighttime face detection also fully demonstrates its promise as a pre-processing means in practical applications.

Efficacy of topical 0.05% cyclosporine A and 0.1% sodium hyaluronate in post-refractive surgery chronic dry eye patients with ocular pain.

BACKGROUND: The management of post-refractive surgery dry eye disease (DED) can be challenging in clinical practice, and patients usually show an incomplete response to traditional artificial tears, especially when it is complicated with ocular pain. Therefore, we aim to investigate the efficacy of combined topical 0.05% cyclosporine A and 0.1% sodium hyaluronate treatment in post-refractive surgery DED patients with ocular pain unresponsive to traditional artificial tears. METHODS: We enrolled 30 patients with post-refractive surgery DED with ocular pain who were unresponsive to traditional artificial tears. Topical 0.05% cyclosporine A and 0.1% sodium hyaluronate were used for 3 months. They were evaluated at baseline and 1 and 3 months for dry eye and ocular pain symptoms and objective parameters, including Numerical Rating Scale (NRS), Neuropathic Pain Symptom Inventory modified for the Eye (NPSI-Eye), tear break-up time (TBUT), Schirmer I test (SIt), corneal fluorescein staining (CFS), corneal sensitivity, and corneal nerve morphology. In addition, tear levels of inflammatory cytokines and neuropeptides were measured using the Luminex assay. RESULTS: After 3 months of treatment, patients showed a statistically significant improvement in the ocular surface disease index (OSDI), TBUT, SIt, CFS, and corneal sensitivity (all P < 0.01) using linear mixed models. As for ocular pain parameters, the NRS and NPSI-Eye scores were significantly reduced (both P < 0.05) and positively correlated with the OSDI and CFS scores. Additionally, tear IL-1ß, IL-6, and TNF-α levels were improved better than pre-treatment (P = 0.01, 0.03, 0.02, respectively). CONCLUSION: In patients with post-refractive surgery DED with ocular pain, combined topical 0.05% cyclosporine A and 0.1% sodium hyaluronate treatment improved tear film stability, dry eye discomfort, and ocular pain, effectively controlling ocular inflammation. TRIAL REGISTRATION: Registration number: NCT06043908.

Radial keratotomy: background and how to manage these patients nowadays.

In this review, we presented the principles of radial keratotomy (RK), its evolution, enhancement, and complications, and strategies to manage the consequences of RK in the present day. It is essential to understand the RK procedure f, the theoretical background that supported this surgery, the current effect on the cornea, and how to approach patients needing vision improvement. These patients are developing cataracts that need to be handled well, from the IOL calculation to the surgical procedure. Guided keratorefractive surgery is the most accurate procedure to improve these patient's vision and life. Nevertheless, some patients may need other approaches, such as sutures, penetrating keratoplasty, corneal rings, and pinhole implants, depending on the degree of irregularity of the cornea, ablation depth for guided surgery or if the sutures are open.

Online intraocular lens calculation.

PURPOSE OF REVIEW: To showcase the majority of online intraocular lens (IOL) calculation tools and highlight some of their characteristics. RECENT FINDINGS: Online tools are available for preoperative and postoperative IOL-related calculations, including IOL power and toricity selection for standard patients, patients who underwent prior refractive surgery, keratoconus, limbal relaxing incisions for astigmatism management, realignment of a misplaced or rotated toric IOL, surgical induced astigmatism (SIA), formulae comparison, and other tools. SUMMARY: As there are new online developments and technology is advancing rapidly, we hope that this review will assist ophthalmologists in becoming acquainted with a large variety of online tools.

Factors influencing dominant eye selection in refractive surgery patients: A correlation analysis.

OBJECTIVE: This study aims to reveal the factors influencing the selection of the dominant eye in refractive surgery patients, and enhance the accuracy of clinical evaluation and surgical treatment. METHODS: A retrospective study method was employed. The ocular biometric parameters were analyzed in 4,114 patients who underwent refractive surgery at the affiliated hospital of Southwest Medical University from 2019 to 2023. RESULTS: The study found that 79.07% of the patients had the right eye as the dominant eye, while 20.93% had the left eye. Although there was no significant difference between the dominant and non-dominant eyes in terms of uncorrected visual acuity and Kappa angle, the dominant eye performed better in aspects such as spherical lens, eye axis, and corneal flat curvature. Furthermore, univariate and multivariate logistic regression results showed that best-corrected visual acuity, pupil diameter, horizontal displacement x-value of the Kappa angle, and astigmatism vector J45 were significant influencing factors for the selection of the dominant eye. CONCLUSION: There are numerous factors affecting the dominant eye, and the most important core factor is J45. This study comprehensively evaluated the possible factors affecting the dominant eye in patients undergoing refractive surgery, which provides a foundation for the designation of refractive surgical modalities and assurance of surgical outcomes, and opens up new perspectives on understanding the mechanisms of the formation and development of the dominant eye.

Evaluation of a Patient Decision Aid for Refractive Eye Surgery.

BACKGROUND: We developed a prototype patient decision aid, EyeChoose, to assist college-aged students in selecting a refractive surgery. EyeChoose can educate patients on refractive errors and surgeries, generate evidence-based recommendations based on a user's medical history and personal preferences, and refer patients to local refractive surgeons. OBJECTIVES: We conducted an evaluative study on EyeChoose to assess the alignment of surgical modality recommendations with a user's medical history and personal preferences, and to examine the tool's usefulness and usability. METHODS: We designed a mixed methods study on EyeChoose through simulations of test cases to provide a quantitative measure of the customized recommendations, an online survey to evaluate the usefulness and usability, and a focus group interview to obtain an in-depth understanding of user experience and feedback. RESULTS: We used stratified random sampling to generate 245 test cases. Simulated execution indicated EyeChoose's recommendations aligned with the reference standard in 243 (99%). A survey of 55 participants with 16 questions on usefulness, usability, and general impression showed that 14 questions recorded more than 80% positive responses. A follow-up focus group with 10 participants confirmed EyeChoose's useful features of patient education, decision assistance, surgeon referral, as well as good usability with multimedia resources, visual comparison among the surgical modalities, and the overall aesthetically pleasing design. Potential areas for improvement included offering nuances in soliciting user preferences, providing additional details on pricing, effectiveness, and reversibility of surgeries, expanding the function of surgeon referral, and fixing specific usability issues. CONCLUSION: The initial evaluation of EyeChoose suggests that it could provide effective patient education, generate appropriate recommendations, connect to local refractive surgeons, and demonstrate good system usability in a test environment. Future research is required to enhance the system functions, fully implement and evaluate the tool in naturalistic settings, and examine the findings' generalizability to other populations.

[Chinese guideline for cataract surgery in adults (2023)].

Cataract is the leading cause of blindness worldwide. In recent years, the annual amount of adult cataract surgery is increasing rapidly. In order to promote the standardization of adult cataract surgery in our country, in accordance with the guiding principles and standards of clinical practice and the existing evidence-based data and expert consensus, Chinese Cataract and Refractive Surgery Society has developed the first clinical guideline in China specifically addressing the surgical treatment of adult cataracts. This guideline focuses on the major clinical issues encountered in adult cataract surgery and aims to provide guidance and reference for ophthalmologists in their clinical practice.

[Comparison of formulas for intraocular lens power calculation after corneal refractive surgery].

Objective: To evaluate the accuracy of five intraocular lens (IOL) power calculation formulas for calculating IOL power in patients with previous myopia-corrected corneal refractive surgery. Methods: In this case series study, a total of 30 eyes of 30 patients who had excimer laser corneal refractive surgery for myopia and subsequent cataract surgery in Qingdao Eye Hospital from April 2020 to October 2022 were included. The Pentacam anterior segment analysis system and IOLMaster were used to measure ocular parameters, including axial length, anterior chamber depth, keratometry, lens thickness, and mean true net power (mTNP). Five formulas were used for IOL power calculation: Shammas formula, Olsen formula, SRK/T (mTNP) formula, Haigis-L formula, and Barrett True-K formula. After cataract extraction, we obtained the actual postoperative refraction by measuring the objective refraction. The prediction error was determined as the difference between the actual postoperative refraction and the predicted refraction, and the absolute value of the prediction error was the absolute error. The differences in the calculation errors of the 5 formulas were compared. Results: Regarding the prediction errors, the results of the SRK/T (mTNP) and Olsen formulas were better than those of Shammas and Haigis-L, and the differences were statistically significant (all P<0.05). The proportion of eyes with an absolute error of 0.50 D for Barrett True-K was highest (70%, 21/30), followed by the SRK/T (mTNP) formula (67%, 20/30). The proportions of eyes with an absolute error within 1.00 D for Barrett True-K, SRK/T (mTNP), and Olsen were all over 80%, with 24 eyes, 24 eyes, and 25 eyes, respectively. Conclusions: The Barrett True-K formula showed high accuracy in predicting the refraction after cataract extraction in patients with a history of corneal refractive surgery for myopia. The calculation result of the Haigis-L formula was highly unstable.

[Analysis of distribution characteristics and influencing factors of chord µ in young myopia].

Objective: To explore and analyze the distribution characteristics of chord µ related parameters, as well as the pupil center's relative position to the coaxial corneal light reflex on the corneal surface, and the influencing factors in young myopia. Methods: This was a cross-sectional study. A total of 761 myopic patients (761 eyes) were collected from March 2021 to December 2021 in the Refractive Surgery Center of Tianjin Eye Hospital, including 388 males and 373 females, with an average age of (24±6) years. The relationship between age, sex, diopter, anterior and posterior corneal surface parameters, and chord µ related parameters was analyzed, including the x and y absolute values of the pupil center, chord µ length, and angle. The normality of the data was tested using the Kolmogorov-Smirnov test, and the influencing factors of chord µ were analyzed through Pearson and Spearman correlation analysis. Results: The equivalent spherical degree and chord µ length were (-5.47±1.66) D and (0.178±0.095) mm, respectively. The chord µ length followed an approximately normal distribution. The chord µ length of 266 eyes (35%) was distributed in the range of 0.120 to 0.200 mm, while the chord µ length of 479 eyes (63%) was<0.200 mm, and the chord µ length of 620 eyes (81%) was<0.260 mm. The chord µ angle distribution accounted for the largest proportion in the superior nasal quadrant (45.6%), followed by the superior temporal quadrant (34.3%), the inferior temporal quadrant (10.1%), and the inferior nasal quadrant (10.0%). High myopia (r=0.11, P=0.002) and high astigmatism (r=0.08, P=0.023) were associated with an increase in chord µ length. The higher the degree of myopia, the smaller the chord µ angle (r=-0.09, P=0.019). The larger the ISV (r=0.09, P=0.017), IVA (r=0.08, P=0.025), and IHD (r=0.08, P=0.039) on the anterior surface of the cornea, the longer the chord µ length. The higher the astigmatism of the posterior corneal surface, the greater the absolute value of the Y coordinate of the pupil center (r=0.07, P=0.044), and the longer the chord µ length (r=0.08, P=0.035), and the smaller the chord µ angle (r=-0.08, P=0.032). Conclusions: The chord µ length of young myopic individuals in China followed an approximately normal distribution, with the majority located in the superior nasal and superior temporal quadrants. High myopia, high astigmatism, and irregular corneal shape are the main factors related to an increase in chord µ length.