Corneal Refractive Surgery Research Articles

The influence of altitude on the differences between Goldmann tonometry and Pascal dynamic contour tonometry: An ecological meta-analysis.

A meta-analysis found that including atmospheric pressure as altitude in generalized linear models reveals higher differences between Goldmann tonometry and Pascal dynamic contour tonometry at higher altitudes, with the difference increasing in thinner corneas. To examine the difference in intraocular pressure (IOP) measurements by using Goldman applanation tonometry (GAT) and dynamic contour tonometer (DCT) tonometry in published literature and determine the influence of central corneal thickness (CCT), age, and altitude on that difference. Articles that compare GAT and DCT were selected for an extensive literature review, and the location and altitude of the research centers were found online. CCT and age were analyzed as covariates, when available. A total of 157 studies including 24,211 eyes of 20,214 patients were included in the study. The results showed that the difference between DCT and GAT was higher at higher altitudes above sea level and increased with thinner corneas. However, the results were different in eyes with corneal transplants, where altitude and CCT had less influence, and in those post-refractive surgery where age was found to influence the difference. Theoretical correction formulas using altitude, CCT, and age were derived from this meta-analysis, but their accuracy and usefulness in clinical practice need validation. The findings suggest that there is a higher risk of underestimating IOP when the Goldmann tonometer is used at a higher altitude, particularly in eyes with glaucoma, thinner corneas, or corneal refractive surgery. Further research is needed to validate the accuracy of the correction formulas derived from this meta-analysis in clinical practice.

Moisture chamber goggles for the treatment of postoperative dry eye in patients receiving SMILE and FS-LASIK surgery

BackgroundThe incidence of refractive surgery-related dry eye disease (DED) is rising due to the increasing popularity of corneal refractive surgery. The moisture chamber goggles (MCGs) have been shown to tear evaporation by increasing local humidity and minimizing airflow. The current study aims to evaluate the efficacy of moisture chamber goggles for refractive surgery-related DED.MethodsIn this nonrandomized open-label controlled study, 78 participants (156 eyes) receiving refractive surgery were enrolled between July 2021 and April 2022, and sequentially allocated to MGC and control groups. 39 participants were allocated to the MGC groups, of which 53.8% received small-incision lenticule extraction (SMILE) and 46.2% received femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and were instructed to wear MCGs for the duration of 1 month postoperatively, in addition to the standard postoperative treatment received by the control groups (56.4% SMILE, 43.6% FS-LASIK). Participants underwent full ophthalmic examinations, including visual acuity, manifest refraction, DED evaluations, and higher-order aberrations (HOAs), both preoperatively and at routine follow-ups 1 day, 1 week, and 1 month after surgery. DED parameters included non-invasive tear film break-up time (NIBUT), tear meniscus height (TMH), conjunctival congestion, lipid layer thickness (LLT), and ocular surface disease index (OSDI) questionnaires. Student’s t-test was used for comparisons between control and MCG groups, and between preoperative and postoperative parameters within groups.ResultsPostoperative NIBUT decreased in both SMILE and FS-LASIK control groups 1 day after the surgery (SMILE, P = 0.001; FS-LASIK, P = 0.008), but not in the corresponding MCG groups (SMILE, P = 0.097; FS-LASIK, P = 0.331). TMH in the MCG group was significantly higher at 1 week (P = 0.039) and 1 month (P = 0.015) in SMILE, and 1 day (P = 0.003) in FS-LASIK groups. In FS-LASIK participants, significantly lower HOAs and coma levels in the MCG group were observed 1 day (total HOAs, P = 0.023; coma, P = 0.004) and 1 week (total HOAs, P = 0.010, coma, P = 0.004) after surgery. No consistent statistically significant intergroup difference was observed between MCG and control groups in conjunctival congestion, LLT, and OSDI.ConclusionsMCGs effectively slowed tear evaporation, increased tear film stability, and improved HOAs in patients receiving SMILE and FS-LASIK surgeries. MCG is an effective adjuvant therapy in the comprehensive management of refractive surgery-related DED.

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

PurposeTo evaluate the efficacy of perioperative IPL therapy in preventing postoperative ocular surface disorders in patients undergoing corneal laser refractive surgery. Designrandomized, controlled, clinical trial with triple-blinding. MethodsSetting: 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. Results61 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). ConclusionsResults 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.

Digital Pupillometry and Centroid Shift Changes in Dominant and Nondominant Eyes.

To investigate the differences between dominant and nondominant eyes in a predominantly young patient population by analyzing the angle kappa, pupil size, and center position in dominant and nondominant eyes. A total of 126 young college students (252 eyes) with myopia who underwent femtosecond laser-combined LASIK were randomly selected. Ocular dominance was determined using the hole-in-card test. The WaveLight Allegro Topolyzer (WaveLight Laser Technologies AG, Erlangen, Germany) was used to measure the pupil size and center position. The offset between the pupil center and the coaxially sighted corneal light reflex (P-Dist) of the patients was recorded by the x- and y-axis eyeball tracking adjustment program of the WaveLight Eagle Vision EX500 excimer laser system (Wavelight GmbH). The patient's vision (uncorrected distance visual acuity [UDVA], best-corrected visual acuity (BCVA), and refractive power (spherical equivalent, SE) were observed preoperatively, 1 week, 4 weeks, and 12 weeks postoperatively, and a quality of vision (QoV) questionnaire was completed. Ocular dominance occurred predominantly in the right eye [right vs. left: (178) 70.63% vs. (74) 29.37%; p < 0.001]. The P-Dist was 0.202 ± 0.095 mm in the dominant eye and 0.215 ± 0.103 mm in the nondominant eye (p = 0.021). The horizontal pupil shift was - 0.07 ± 0.14 mm in dominant eyes and 0.01 ± 0.13 mm in nondominant eyes (p = 0.001) (the temporal displacement of the dominant eye under mesopic conditions). The SE was negatively correlated with the P-Dist (r = - 0.223, p = 0.012 for the dominant eye and r = - 0.199, p = 0.025 for the nondominant eye). At 12weeks postoperatively, the safety index (postoperative BDVA/preoperative BDVA) of the dominant and nondominant eyes was 1.20 (1.00, 1.22) and 1.20 (1.00, 1.20), respectively, and the efficacy index (postoperative UDVA/preoperative BDVA) was 1.00 (1.00, 1.20) and 1.00 (1.00, 1.20), respectively; the proportion of residual SE within ± 0.50 D was 98 and 100%, respectively. This study found that ocular dominance occurred predominantly in the right eye. The pupil size change was larger in the dominant eye. The angle kappa of the dominant eye was smaller than that of the nondominant eye and the pupil center of the dominant eye was slightly shifted to the temporal side under mesopic conditions. The correction of myopia in the dominant and nondominant eyes exhibits good safety, efficacy, and predictability in the short term after surgery, and has good subjective visual quality performance after correction. We suggest adjusting the angle kappa percentage in the dominant eye to be lower than that of the nondominant eye in individualized corneal refractive surgery in order to find the ablation center closest to the visual axis.

Contribution of Posterior Corneal Astigmatism to Total Corneal Astigmatism among Saudi Population

Background: Astigmatism is an error of refraction in which incident parallel rays cannot be focused on a single point. It could be corneal astigmatism (CA), lenticular astigmatism (LA), or both. Regarding CA, it is due to the difference in the corneal curvature in the different meridians of both the anterior and posterior surfaces. The anterior and posterior corneal surfaces contribute to total corneal astigmatism (TCA). Newer technologies, such as slit-scanning technology, Scheimpflug devices, and optical coherence tomography, are now used in the clinical setting for measuring the posterior corneal surface. However, it has been shown that relying only on the anterior corneal surface measurement and neglecting the relationship between the anterior and posterior corneal surfaces can lead to unacceptable intraocular lens (IOL), power calculation results after corneal refractive surgery, and errors during the calculation of toric IOLs. Objectives: This study aimed to determine the percentage of contribution of the magnitude of posterior corneal astigmatism (PCA) to total corneal astigmatism (TCA) and to investigate the correlation between anterior corneal astigmatism (ACA), PCA, and TCA. Methods: A prospective cross-sectional study including 55 subjects aged 18 – 31 years old and divided into 3 groups based on spherical equivalent (SE), Emmetropia, Hyperopia, and Myopia were included. All subjects underwent full ophthalmological examinations and corneal topography. ACA and PCA were evaluated. TCA was computed by the addition of the ACA and PCA using vector analysis. The percentage of contribution of the PCA to the magnitude of the TCA and the correlation between ACA, PCA, and TCA were calculated. Results: All subjects had anterior corneal with the rule (WTR) astigmatism. The contribution of PCA to TCA for all subjects in 3 groups (Emmetropia, Hyperopia, and Myopia) was 35%, 37%, and 37%, respectively, with P &gt; 0.05, which was not statistically significant. There was a correlation between ACA, PCA, and TCA in all study groups. Conclusion: TCA is composed of both corneal surfaces, and PCA impacts the outcomes of refractive surgeries for correcting astigmatism and in toric intraocular lens (IOL) calculation when just based on the data of the anterior corneal surface.

Early outcomes of second-generation light-adjustable lenses in eyes with and without corneal refractive surgery.

Early outcomes of second-generation light-adjustable lenses in eyes with and without corneal refractive surgery.

Assessment of Keratoconus Risk in Very Asymmetric Ectasia Using Corneal Tomographic and Biomechanical Parameters.

To investigate the relationship between corneal tomographic or biomechanical parameters and risk of keratoconus in very asymmetric ectasia (VAE). This retrospective case-control single-centre study included patients with VAE and normal controls. The VAE group had clinical ectasia in one eye and normal topography (VAE-NT) in the fellow eye; VAE-NT eyes were selected for analysis. The control group was selected from corneal refractive surgery candidates; the right eye was enrolled. Scheimpflug-based corneal tomography (Pentacam) and corneal biomechanical assessment (Corvis ST) were performed. Univariate and multivariable logistic regression were performed using Cox proportional hazards models to evaluate keratoconus-associated risk factors. A two-piecewise linear regression model was applied to examine the threshold effect of selected vital paragmeters on the risk of keratoconus according to a smoothing plot. Threshold effect between tomographic integration and risk of keratoconus was observed. Discrepancy between the central corneal thickness and thinnest corneal thickness (discrepancy CCT vs TCT) greater than 5 μm, discrepancy between the apex corneal thickness and thinnest corneal thickness (discrepancy ACT vs TCT) greater than 3 μm, vector distance between CCT and TCT (distance CCT vs TCT) greater than 0.65 mm indicated a significant increased risk of keratoconus. Risk of keratoconus decreased when distance CCT vs TCT was less than 0.65 mm. Discrepancy CCT vs TCT, discrepancy ACT vs TCT, and distance CCT vs TCT can be used as indicators for risk assessment of early keratoconus.

Accuracy of the PEARL-DGS Formula for Intraocular Lens Power Calculation in Post–Myopic Laser Refractive Corneal Surgery Eyes

PurposeTo investigate the accuracy of the PEARL-DGS formula for intraocular lens (IOL) power calculation in post-myopic laser refractive corneal surgery eyes. DesignRetrospective case series MethodsA total of 139 eyes of 139 patients (mean axial length: 27.4 ± 2.1 mm), who had prior myopic laser refractive corneal surgery and subsequent cataract surgery using Tecnis ZCB00 from March 2018 to February 2023 were included. Refractive outcomes of five formulas (Barrett True K, Haigis-L, Hoffer-QST, PEARL-DGS, and Shammas-PL) were evaluated. Prediction error was defined as the difference between the measured and predicted postoperative refractive spherical equivalent using the IOL power actually implanted. Mean prediction error (MPE), median absolute prediction error (MedAE), mean absolute prediction error were calculated. ResultsWithout constant optimization, the PEARL-DGS resulted in a MPE of +0.05 ± 0.65 D, while the other formulas resulted in myopic shifts. The MedAEs of the formulas were 0.39, 0.53, 0.65, 0.85, and 1.11 D for the PEARL-DGS, Hoffer-QST, Barrett True K, Shammas-PL, and Haigis-L, respectively, in order of magnitude (P < 0.05). With constant optimization, there were no statistically significant differences in the MedAEs among the five formulas (P = 0.388). ConclusionsIn comparison to other IOL formulas, the PEARL-DGS resulted in better refractive outcomes after cataract surgery in post-myopic laser refractive corneal surgery eyes without constant optimization. We suggest that PEARL-DGS be considered as the first choice for IOL power calculation in these eyes when the clinicians do not have their optimized constants.

Dry eye disease among patients infected with the SARS-CoV-2 Omicron variant: a cross-sectional study.

To investigate the incidence of dry eye disease (DED) and relevant risk factors among patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant. This cross-sectional, observational analysis included 993 patients with corona virus disease 2019 (COVID-19) treated at the National Exhibition and Convention Center (Shanghai) Fangcang Shelter Hospital, from April 10 to May 26, 2022. Totally 944 uninfected control participants were recruited. All participants completed ocular surface disease index (OSDI) questionnaires, and DED symptoms were determined using OSDI scores. The demographic characteristics, length of hospital stay and in nasopharyngeal swabs were performed using questionnaires. SARS-CoV-2 Omicron variant infection was confirmed by nucleic acid-based detection in nasopharyngeal swabs using a 2019-nCoV nucleic acid detection kit. The risk factors for DED symptoms among patients with COVID-19 and control participants were determined by logistic regression analysis. Patients with COVID-19 showed a higher incidence of DED than controls (64.9% vs 55.1%, P<0.001). SARS-CoV-2 infection [odds ratios (ORs) (95%CI): 1.271 (1.038, 1.556)], use of contact lenses [ORs (95%CI): 9.350 (3.676, 23.783)], history of corneal refractive surgery [ORs (95%CI): 2.047 (1.494, 2.804)], poor sleep quality [ORs (95%CI): 2.657 (2.029, 3.480)], and video display terminal (VDT) use for more than 8h per day [ORs (95%CI): 6.348 (4.720, 8.538)] were found to be risk factors for DED symptoms in patients with COVID-19 as well as controls. For patients with COVID-19, the length of hospital stay [ORs (95%CI): 1.196 (1.134, 1.262)], use of contact lenses [ORs (95%CI): 20.423 (2.680, 155.632)], history of corneal refractive surgery [ORs (95%CI): 2.166 (1.321, 3.553)], poor sleep quality [ORs (95%CI): 3.650 (2.381, 5.597)], and VDT use for more than 8h per day [ORs (95%CI): 7.740 (4.918, 12.180)] were significant risk factors for DED symptoms. Patients with COVID-19 are more prone to develop symptomatic DED. SARS-CoV-2 infection and length of hospital stay are important risk factors for DED symptoms.

Effect of Chalazion on Corneal Astigmatism

A common eyelid disease chalazion causes eye morbidity due to inflammation and cosmetic disfigurement. Important factors in corneal refractive surgery, intraocular lens power calculations for cataract surgery and visual acuity assessments are corneal topographic changes. For better outcome of ocular surgery corneal astigmatism should be corrected earlier. The aim of this study is to evaluate changes in corneal astigmatism according to chalazion size and location. Methods: This cross-sectional study was conducted in saveetha medical college and hospitals, Thandalam , Department of Ophthalmology Outpatient department. A total of 44 eyes from 33 patients were included in the chalazion group and 70 eyes from 46 patients comprised the control group. Chalazia were classified according to location and size. An autokeratorefractometer and a dual-Scheimpflug analyzer were utilized to evaluate corneal changes. Result: Oblique astigmatism was greater in the chalazion group compared with the control group (p &lt; 0.05). Astigmatism by simulated keratometry (simK), steep K by simK, total root mean square, second order aberration, oblique astigmatism, and vertical astigmatism were significantly greater in the upper eyelid group (p &lt; 0.05). Astigmatism by simK, second order aberration, oblique astigmatism, and vertical astigmatism were significantly greater in the large-sized chalazion group (p &lt; 0.05). Corneal wavefront aberration was the greatest in the upper eyelid chalazion group, whole area group, and large-sized chalazion group (p &lt; 0.05). Conclusions: Large-sized chalazion in the upper eyelid should be treated in the early phase as great changes in corneal topography were noticed. Corneal topography should be performed preoperatively before chalazion is treated.

Applications of anterior segment optical coherence tomography in corneal refractive surgery

Anterior segment optical coherence tomography (AS-OCT) has the characteristics of non-contact, noninvasive, high sensitivity, and repeatability, and offers high-resolution in vivo imaging of the structures of the anterior eye segment. It can be used in the diagnosis and assistance of conditions related to the anterior eye segment. This review provides an update on the research and clinical applications of AS-OCT in corneal refractive surgery, including preoperative keratoconus screening, intraoperative real-time visualization of corneal structures, postoperative corneal evaluation, and management of postoperative complications. We also explore the potential application of AS-OCT in combination with corneal biomechanical detection for corneal refractive surgery.

The impact of patient-reported visual disturbance on dynamic visual acuity in myopic patients after corneal refractive surgery.

To investigate the impact of patient-reported visual disturbance on dynamic visual acuity in myopic patients after corneal refractive surgery. This is a prospective nonrandomized study. Adult myopic patients receiving bilateral laser-assisted sub-epithelial keratomileusis (LASEK), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), or small incision lenticule extraction (SMILE) with Plano target were included. Eight types of patient-reported visual disturbance were evaluated regarding frequency, severity and bothersome and dynamic visual acuity (DVA) of 40 and 80 degrees per second (dps) was measured postoperatively at 3 months. The study enrolled 95 patients with an average age of 27.6 ± 6.4 years. The most frequently reported visual disturbance was the fluctuation in vision (70.5%), followed by glare (66.3%) and halo (57.4%). Postoperative DVA at 80 dps was significantly associated with the total score of haloes (p = 0.038) and difficulty in judging distance (p = 0.046). Significant worse postoperative DVA at 40 dps was observed in patients with haloes than those without (p = 0.024). The DVA at 80 dps for patients without haloes or difficulty in judging distance was significantly better than that with the symptoms (haloes, p = 0.047; difficulty in judging distance, p = 0.029). Subgroup analysis by surgical procedures demonstrated that the significant difference in DVA between patients with and without visual disturbance was only observed in patients receiving FS-LASIK. Postoperatively, myopic patients undergoing corneal refractive surgery with haloes or difficulty in judging distance have significantly worse low and high-speed DVA than those without the symptoms. The present study provided the basis for postoperative guidance in daily tasks involving dynamic vision when patients have visual disturbances.

Intraocular Pressure Changes in Myopic Patients Undergoing Laser In-Situ Keratomileusis and Photorefractive Keratectomy.

To assess the variation in intraocular pressure measurements between Ocular Response Analyzer (ORA) and Goldmann Applanation Tonometer (GAT) in myopic patients undergoing laser assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Quasi-experimental study. Place and Duration of the Study: Armed Forces Institute of Ophthalmology (AFIO), National University of Medical Sciences, Rawalpindi, Pakistan, between September 2020 and 2021. Myopic patients undergoing LASIK and PRK during the study period were selected. Baseline examinations and postoperative follow-ups were carried out to measure intraocular pressure at 1, 3, and 6 months after LASIK or PRK, using Goldmann Applanation Tonometer (GAT) and Ocular Response Analyzer, corneal compensated IOP (ORA IOPcc). One hundred and thirteen eyes underwent myopic refractive surgery, LASIK (n = 60) or PRK (n = 53). Mean age of patients was 23.6 ± 4.11 years in the PRK group and 24.4 ± 5.94 years in LASIK group. For the PKR group, the GAT IOP value increased at 1-month (p <0.001), decreased at 3-month (p <0.001) and further decreased at 6-month (p <0.001) follow-up postoperatively. In the LASIK group, the GAT IOP value decreased at all time points (p <0.001). In both groups, the mean ORA IOPcc value increased at 1 month (p <0.001), decreased at 3-month (p <0.001) and further decreased at 6-month (p <0.001) follow-up postoperatively. The IOP mean values were generally found to be higher when measured using ORA as compared with GAT. Corneal refractive surgery markedly decreased IOP. This decrease in IOP was observed more after LASIK than after PRK. ORA was less likely to underestimate the intraocular pressure than GAT. Myopia, Laser in-situ keratomileusis, Photorefractive keratectomy, Tonometery ocular, Intraocular pressure.

Challenges of refractive cataract surgery in the era of myopia epidemic: a mini-review.

Myopia is the leading cause of visual impairment in the world. With ever-increasing prevalence in these years, it creates an alarming global epidemic. In addition to the difficulty in seeing distant objects, myopia also increases the risk of cataract and advances its onset, greatly affecting the productivity of myopes of working age. Cataract management in myopic eyes, especially highly myopic eyes is originally more complicated than that in normal eyes, whereas the growing population of cataract with myopia, increasing popularity of corneal and lens based refractive surgery, and rising demand for spectacle independence after cataract surgery all further pose unprecedented challenges to ophthalmologists. Previous history of corneal refractive surgery and existence of implantable collamer lens will both affect the accuracy of biometry including measurement of corneal curvature and axial length before cataract surgery, which may result in larger intraocular lens (IOL) power prediction errors and a compromise in the surgical outcome especially in a refractive cataract surgery. A prudent choice of formula for cataract patients with different characteristics is essential in improving this condition. Besides, the characteristics of myopic eyes might affect the long-term stability of IOL, which is important for the maintenance of visual outcomes especially after the implantation of premium IOLs, thus a proper selection of IOL accordingly is crucial. In this mini-review, we provide an overview of the impact of myopia epidemic on treatment for cataract and to discuss new challenges that surgeons may encounter in the foreseeable future when planning refractive cataract surgery for myopic patients.

Assessment of Pupil Size and Angle Kappa in Refractive Surgery: A Population-Based Epidemiological Study in Predominantly American Caucasians.

Purpose This retrospective study aims to establish normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type in a largely Caucasian population in Utah, United States, utilizing the NIDEK OPD-Scan III system (Gamagori, Japan). Methods This study included 716 patients (1432 eyes) grouped based on spherical equivalence and age. Measurements were conducted under mesopic and photopic conditions. Statistical analysis involved Pearson's correlation and linear regression using the generalized estimating equation.NIDEK OPD-Scan III measured mesopic and photopic pupil size and angle kappa. The subjects were then grouped based on their spherical equivalence in diopters (D) and age in decades. The spherical equivalence groups were defined: >-6 D, -5.99to -3 D, -2.99to -0.25 D, -0.24to 0.24 D, and >0.25 D (range 0.25-5.75 D). The higher-order aberration groups were based on the reason for the visit: laser-assisted in situ keratomileusis, photorefractive keratectomy, and small incision lenticule extraction as one group; cataract evaluation; and keratoconus. Astigmatism measurements were grouped into with-the-rule (WRT), against-the-rule (ATR), and oblique astigmatism, with further subgrouping into a young cohort (20-40 years) and an old cohort (>65 years). Results Among 716 participants, 49.2% were men; the mean age was 42.1±15.5(range 7-88 years). The average spherical equivalence for myopia eyes was -3.28±2.34 D, and 1.51±1.46 D for hyperopia eyes. The mean mesopic pupil size was 5.68 ± 1.09 mm; the photopic pupil size was 4.65±1.09 mm. Pearson's correlation coefficient for mesopic pupil size versus age was -0.551, and -0.42 for photopic pupil (p < 0.001); sphere vs mesopic pupil size was -0.200, and -0.173 for photopic pupil(p < 0.001). The regression analysis for mesopic pupil size versus age revealed a 0.39 mm decrease in average pupil size per decade increase in age, and 0.25 mm decrease per decade for photopic pupil. The regression analysis for mesopic pupil size versus sphere revealed a 0.22 mm decrease in average pupil size per 3D increase in sphere, and a 0.16 mm decrease 3 D increase in sphere for the photopic pupil. The mean mesopic angle kappa was 0.33± 0.15 mm; photopic angle kappa was 0.31±0.15 mm. Pearson's correlation coefficient for mesopic angle kappa vs spherical equivalence was 0.32, and 0.296 for photopic angle kappa (p <0.001 for both). Regression analysis for mesopic angle kappa vs spherical equivalence demonstrated a 0.051 mm increase in angle kappa per 3 D increase in spherical equivalence, and a 0.048 mm increase for photopic angle kappa (p < 0.001 for both). Among the higher-order aberration groups, the keratoconus group exhibited the highest levels. In terms of astigmatism type, WRT astigmatism was the most common in the young cohort, while ATR astigmatism was most prevalent in the older cohort. Conclusions The results of this study reveal significant associations between pupil size and increasing age, as well as between pupil size and increasingly positive refractive errors. These findings hold particular clinical relevance to older patients and individuals with hyperopia, as they undergo photoablative corneal refractive surgery or multifocal intraocular lens implantation. Understanding the established normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type can aid clinicians in making more informed decisions and improving patient outcomes.

A Literature Review of the Incidence, Management, and Prognosis of Corneal Epithelial-Related Complications After Laser-Assisted In Situ Keratomileusis (LASIK), Photorefractive Keratectomy (PRK), and Small Incision Lenticule Extraction (SMILE).

Our purpose is to provide a comprehensive investigation into the incidence, treatment modalities, and visual prognosis of epithelial-related complications in corneal refractive surgeries, including laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE). A systematic search of multiple databases was conducted by two independent examiners using various search terms related to epithelial-related complications and corneal refractive surgeries.A total of 91 research articles were included, encompassing a sample size of 66,751 eyes across the three types of surgeries. The average incidence of epithelial-related complications varied across the different types of corneal refractive surgeries. LASIK had an average incidence of 4.9% for epithelial defects, while PRK and SMILE had lower rates of 3.3% and 3.9%, respectively. Our findings indicate that SMILE has a lower incidence of epithelial defects compared to LASIK, potentially due to the less invasive nature of lenticule incision in SMILE.Visual prognosis after epithelial complications (EC) is generally favorable, with various supportive care and surgical interventions leading to significant improvements in postoperative visual acuity and full recovery. Understanding the incidence rates and management approaches for epithelial-related complications can guide clinicians in enhancing patient safety, refining surgical techniques, and optimizing postoperative outcomes in corneal refractive surgeries.

Repeatability of pupil diameter measurements using three different topography devices.

To evaluate the intra- and inter-device repeatability of pupil diameter measurements using three different devices in patients prior to corneal refractive surgery. We examined preoperative measurements from a total of 204 eyes (102 patients) scheduled for corneal refractive surgery at two private centers between July and December 2021. Three consecutive scans were performed with three different devices (Sirius anterior segment analyzer, Pentacam HR, IOLMaster 500) in the same session by the same examiner under standardized conditions. To assess the intra- and inter-device repeatability, we calculated the Intraclass Correlation Coefficient (ICC) and demonstrated results using Bland-Altman plots. The measurement accuracy (intra-device repeatability) of Sirius and IOLMaster was comparable (ICC = 0.64 and 0.61, respectively), with almost no statistically significant differences. Sirius showed the highest measurement accuracy among the three devices. Pentacam measurements resulted in lower precision, with an ICC of 0.09. The agreement between the pairs of devices (inter-device repeatability) was low (wide LoA ranges, Table 5). In this study, the intra-device repeatability of Sirius and IOLMaster was higher than that of the Pentacam, although it did not achieve an optimal level across all three devices. The three devices examined cannot be used interchangeably.

Clinical analysis of corneal interface infection

Objective: To analyze the clinical features of corneal interface infection. Methods: A retrospective case series study was conducted to explore the clinical features of interstitial corneal infection. The data of eight patients (eight eyes) who were diagnosed with interstitial corneal infection after undergoing corneal transplant or corneal refractive surgery and visited Beijing Tongren Eye Center from January to December 2018 were collected, including two male and six female patients aged between 18 and 55 years (median age, 27 years). The patients' general information, surgical type, onset time, and clinical manifestations were recorded. The lesions were examined by in vivo corneal laser confocal microscopy (IVCM), and microbial cultures and drug sensitivity tests were performed. Results: Among the 8 patients, 4 had undergone small-incision lenticule extraction (SMILE), 2 had undergone lamellar keratoplasty, and 2 had undergone endothelial keratoplasty. The onset of infection occurred between 2 and 30 days after surgery, with a mean of 9.8 days. Among the 3 patients who had undergone SMILE, the treatment outcome was corneal haze or opacity, while the remaining 5 cases required corneal transplantation for interstitial infections. The pathogens of the 4 cases of interstitial infection after corneal transplantation were all Candida species. Under the IVCM, patients with corneal interstitial bacterial infections showed a large amount of necrotic tissue with no normal tissue structure in the corneal stroma, with infiltration of inflammatory cells and local aggregation of inflammatory cells, but no typical pathogen was observed. Patients with fungal infections showed fungal hyphae under the corneal cap (filamentous fungal infection) or dense, punctate, high-reflection structures in the corneal interstitial space (yeast-like fungal infection). Conclusions: Corneal interlayer infection is difficult to diagnose early and has a poor prognosis. IVCM can assist in early diagnosis. The pathogen spectrum of corneal interlayer infection may differ from that of corneal infection caused by trauma.

Corneal biomechanics after small incision lenticule extraction and femtosecond laser in situ keratomileusis: A systematic review and meta-analysis.

Small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) have been extensively studied as the main surgical methods for corneal refractive surgery. However, there is no consensus on whether SMILE is superior to FS-LASIK in corneal biomechanics. Therefore, this systematic review and meta-analysis used the results of ocular response analyzer and corvis ST to explore whether SMILE is superior to FS-LASIK in corneal biomechanics. The literature was searched in PubMed, EMBASE, and Controlled Trials Register databases. The Cochrane Collaboration's "risk of bias" tool was used to evaluate the quality of the included randomized clinical trials, and the Newcastle-Ottawa Scale was used to evaluate the included non-randomized controlled trials. The results were analyzed using Revman 5.3. Sixteen studies (3 randomized clinical trials and 13 non-randomized controlled trials) were included in this meta-analysis. There was no statistical difference in corneal biomechanics between SMILE and FS-LASIK in corneal hysteresis [mean difference (MD), 0.20; 95% confidence interval (CI): -0.09, 0.49; P = .18] and corneal resistant factor (MD, 0.31; 95% CI: -0.09, 0.71; P = .13), A1 time (MD, -0.02; 95% CI: -0.11, 0.07; P = .66), A1 length (MD, 0.01; 95% CI: -0.01, 0.03; P = .42), A1 velocity (MD, 0.00; 95% CI: -0.01, 0.01; P = .85), A2 velocity (MD, -0.01; 95% CI: -0.11, 0.09; P = .86), HC time (MD, 0.12; 95% CI: -0.13, 0.38; P = .35), The stiffness parameter at first applanation (MD, -7.91; 95% CI: -17.96, 2.14; P = .12), The ratio between the deformation amplitude 2 mm away from apex and the apical deformation (MD, 0.01; 95% CI: -0.26, 0.27; P = .96). A comprehensive assessment of the parameters of ocular response analyzer and corvis ST showed that SMILE is not superior to LASIK in corneal biomechanics 3 months post-surgery.

Bibliometric and visualized analysis of myopic corneal refractive surgery research: from 1979 to 2022.

Myopic corneal refractive surgery is one of the most prevalent ophthalmic procedures for correcting ametropia. This study aimed to perform a bibliometric analysis of research in the field of corneal refractive surgery over the past 40 years in order to describe the current international status and to identify most influential factors, while highlighting research hotspots. A bibliometric analysis based on the Web of Science Core Collection (WoSCC) was used to analyze the publication trends in research related to myopic corneal refractive surgery. VOSviewer v.1.6.10 was used to construct the knowledge map in order to visualize the publications, distribution of countries, international collaborations, author productivity, source journals, cited references, keywords, and research hotspots in this field. A total of 4,680 publications on myopic corneal refractive surgery published between 1979 and 2022 were retrieved. The United States has published the most papers, with Emory University contributing to the most citations. The Journal of Cataract and Refractive Surgery published the greatest number of articles, and the top 10 cited references mainly focused on outcomes and wound healing in refractive surgery. Previous research emphasized "radial keratotomy (RK)" and excimer laser-associated operation methods. The keywords containing femtosecond (FS) laser associated with "small incision lenticule extraction (SMILE)" and its "safety" had higher burst strength, indicating a shift of operation methods and coinciding with the global trends in refractive surgery. The document citation network was clustered into five groups: (1) outcomes of refractive surgery: (2) preoperative examinations for refractive surgery were as follows: (3) complications of myopic corneal refractive surgery; (4) corneal wound healing and cytobiology research related to photorefractive laser keratotomy; and (5) biomechanics of myopic corneal refractive surgery. The bibliometric analysis in this study may provide scholars with valuable to information and help them better understand the global trends in myopic corneal refractive surgery research frontiers. Two stages of rapid development occurred around 1991 and 2013, shortly after the innovation of PRK and SMILE surgical techniques. The most cited articles mainly focused on corneal wound healing, clinical outcomes, ocular aberration, corneal ectasia, and corneal topography, representing the safety of the new techniques.