Refractive Correction Research Articles

The application of rigid gas permeable contact lenses after surgery for infantile nystagmus syndrome

The purpose of this study is to investigate the improvement in visual acuity when applying Rigid Gas Permeable Contact Lenses (RGPCL) compared to spectacles in patients after surgical treatment for infantile nystagmus syndrome (INS). A total of 33 patients with nystagmus who had nystagmus surgery from October 2020 to July 2021 were enrolled and all were fitted RGPCL. SPSS statistical software was used to analyze the difference between best-corrected visual acuity with spectacle(BCSVA) and best-corrected visual acuity with RGPCL (BCRVA) in these patients. According to the refractive status of each eye, it was grouped into 2 groups. We study the difference between its BCSVA and BCRVA in different groups. In our study, BCRVA was significantly better than BCSVA in all participants (P < 0.001), with a strong positive correlation between them (overall r = 0.9333). In Group A (SE ≥ -3.00D, 15 eyes), the difference was significant (P = 0.0018), while in Group B (SE < -3.00D, 27 eyes), the difference was highly significant (P < 0.001). However, there was no significant difference in corrective visual acuity between the two groups (P = 0.5934). The mean difference between BCRVA and BCSVA was − 0.1160 ± 0.1221 in all participants, with similar differences in both groups. These findings suggest that BCRVA and BCSVA are closely related but with significant differences. The results of our study show that for patients who have undergone surgery for INS, RGPCL provide better best-corrected visual acuity compared to spectacle correction. This holds true for patients with high myopia, low myopia, and hyperopia. We recommend the use of RGPCL for refractive correction in patients after surgery for INS.

Using polarization to estimate surface normals at air-water interfaces for correction of refraction in seafloor imaging

Using polarization to estimate surface normals at air-water interfaces for correction of refraction in seafloor imaging

A pigment dispersion syndrome case with concave iris and ocular hypertension managed through a phakic ICL implantation.

A concave iris configuration is a characteristic feature of pigment dispersion syndrome (PDS). Therapeutic strategies to modify this configuration may be considered as first-line options for the treatment of ocular hypertension in PDS patients. A 37-year-old male patient with myopic anisometropia presented bilateral PDS with concave iris, Krukenberg's spindle and iris transillumination defect in both eyes. The intraocular pressure (IOP) was 27 mmHg in both eyes. Optic nerve and visual field parameters were normal. The right eye was treated with a neodymium:YAG LPI. In the left eye, an implantable collamer lens (ICL) V4c model implantation for myopia correction was performed. Six-months postoperatively, both eyes evidenced an anteriorization of the iris, the morphology of the concave iris improved with the ICL V4c in place, becaming flattener in left eye. The IOP was 18 mmHg without treatment. This case report reinforces the idea that in myopic patients with a concave iris, the refractive correction approach through ICL V4c implantation might also improve the iris configuration, similarly to laser peripheral iridotomy (LPI). Therefore, in this specific patient profile, this surgical procedure might be considered as a prophylactic treatment alternative to prevent the complications associated with this iris configuration, although its invasive nature should be taken into consideration.

Refraction-Aware Structure from Motion for Airborne Bathymetry

In this work, we introduce the first pipeline that combines a refraction-aware structure from motion (SfM) method with a deep learning model specifically designed for airborne bathymetry. We accurately estimate the 3D positions of the submerged points by integrating refraction geometry within the SfM optimization problem. This way, no refraction correction as post-processing is required. Experiments with simulated data that approach real-world capturing conditions demonstrate that SfM with refraction correction is extremely accurate, with submillimeter errors. We integrate our refraction-aware SfM within a deep learning framework that also takes into account radiometrical information, developing a combined spectral and geometry-based approach, with further improvements in accuracy and robustness to different seafloor types, both textured and textureless. We conducted experiments with real-world data at two locations in the southern Mediterranean Sea, with varying seafloor types, which demonstrate the benefits of refraction correction for the deep learning framework. We made our refraction-aware SfM open source, providing researchers in airborne bathymetry with a practical tool to apply SfM in shallow water areas.

Refractive development II: Modelling normal and myopic eye growth.

During refractive development, eye growth is controlled by a combination of genetically pre-programmed processes and retinal feedback to minimise the refractive error. This work presents a basic differential model of how this process may take place. The description starts from two bi-exponential descriptions of the axial power Pax (or dioptric distance) and total refractive power Peye, the difference between which corresponds with the spherical refractive error S. This description is rewritten as an ordinary differential equation and supplemented by a retinal feedback function that combines retinal blur (closed loop) with a term describing excessive axial growth (open loop). This model is controlled by a total of 18 parameters that allow for a wide variety of developmental behaviours. The proposed model reproduces refractive development growth curves found in the literature for both healthy and myopic eyes. An early onset of myopisation, a large growth term and a high minimum for the crystalline lens power all lead to higher degrees of myopia. Assigning more importance to the feedback than to the pre-programmed growth makes the model more sensitive to myopogenic influences. Applying refractive corrections to the model, undercorrection is found to produce more myopia. The model compensates for a low-powered imposed lens and can return to (near) emmetropia if that imposed lens is removed quickly thereafter. Finally, simulating the effect of a diffuser leads to high myopia. Using a series of basic assumptions, the proposed model recreates many well-known experimental and clinical results about refractive development from the literature while placing them in a standardised context. This contributes to a broader understanding of the origins of refractive errors, and future versions may help in the development of solutions for myopia control.

Early assessment of vision-related quality of life predicts long-term spectacle-wear compliance

Non-compliance with spectacle wear undermines global health initiatives aimed at eliminating uncorrected refractive error—a preventable cause of visual impairment—by providing free or affordable spectacles to underserved populations. Non-compliance, however, is often identified too late, delaying effective health promotion strategies. This study evaluates the association between early-assessed vision-related quality of life (QoL) following spectacle correction and long-term compliance in adults. A comprehensive eye examination was conducted on 3052 university students to identify those visually impaired (presenting acuity ≥ Snellen 6/12 in the better eye) due to uncorrected refractive error. After refractive correction, participants achieving a best-corrected visual acuity of Snellen 6/6 completed the National Eye Institute 25-item Visual Function Questionnaire (NEI-VFQ-25) at baseline and within the first week of correction. A 6-month follow-up assessed compliance with spectacle wear. The average baseline NEI-VFQ-25 score improved from 67.35 (± 13.53%) to 90.56 (± 8.45%) with spectacle correction (P < 0.001) in the first week, with individual changes ranging from 2 to 70%. After 6 months, only 54 (47%) out of the 115 eligible participants (58 females; ages 18 to 29) were compliant. Following the adjustment for covariates, the results revealed that gains in NEI-VFQ-25 score below 40 were significantly associated with reduced compliance over the 6-month period (OR: 0.39, 95% CI: 0.06–0.99, P = 0.047). This supports an association between early vision-related QoL and long-term compliance. Scheduling a short follow-up to assess vision-related QoL within the first week after dispensing spectacles may help identify potential non-compliant wearers early, allowing for timely interventions.

Corneal sensitivity and ocular surface health in patients undergoing femtosecond LASIK retreatment for residual refraction.

To assess corneal sensitivity and the ocular surface in patients undergoing primary femtosecond laser in situ keratomileusis (FS-LASIK) and those undergoing FS-LASIK retreatment under the same flap due to residual refractive error. Ekol Eye Hospital, Izmir, Turkey. Prospective case series. 19 patients with previous FS-LASIK who had myopic and astigmatic refractive error were included in the study group, and 19 age-matched and sex-matched patients undergoing FS-LASIK for the first time as the control group. Corneal sensitivity, Schirmer test, tear film break-up time (TBUT), Oxford grading scheme for ocular surface staining, and Ocular Surface Disease Index (OSDI) were measured preoperatively and at postoperative 1 week and 1, 3, and 6 months. The mean refractive correction in the study and control groups, respectively, was 2.18 ± 0.78 diopters (D) (range: 1.00 to 3.50) and 2.76 ± 1.20 D (range: 1.00 to 4.50; P = .07). Corneal esthesiometry results in the study and control groups, respectively, were 6.10 ± 12.55 vs 9.90 ± 11.50 mm at 1 week ( P = .001), 41.95 ± 6.98 vs 45.09 ± 5.88 mm at 1 month ( P = .004), 56.09 ± 3.37 vs 56.19 ± 2.52 mm at 3 months ( P = .8), and 58.60 ± 2.01 vs 58.80 ± 1.39 mm at 6 months ( P = .5). Significant difference between the 2 groups in Schirmer test score that disappeared at postoperative 3 months and in TBUT and ocular surface staining that disappeared at 6 months, whereas the statistically significant difference in OSDI score persisted at 6 months ( P = .03) was detected. Corneal surface sensitivity and ocular surface health are more impaired in patients undergoing FS-LASIK retreatment due to residual refractive error.

Evidence-based Guidelines for Keratorefractive Lenticule Extraction Surgery

Development of evidence-based guidelines for keratorefractive lenticule extraction (KLEx). KLEx refers to various corneal refractive procedures involving removal of refractive lenticules of intrastromal corneal tissue, typically through a small incision, thereby eliminating creation of a corneal flap. This technique has rapidly gained popularity as a possible alternative to flap-based procedures; however, no clinical practice guidelines exist for KLEx. These evidence-based guidelines were developed following the WHO guidebook, utilizing the AGREE II tool, and adhering to the RIGHT statement. The body of evidence was drawn from eight literature databases, five clinical guideline databases, and two academic organizations. Recommendations were developed via a Delphi consensus of 44 global experts in refractive surgery, corneal diseases, retinal diseases, glaucoma, and optometry. The certainty of evidence, balance of benefits and harms, patient preferences and values, and economic evaluations were fully considered. The GRADE approach was employed to assess evidence quality and recommendation strengths. From 385 initial clinical questions, 15 were identified, prompting a review of 250,717 studies, with 609 included for conducting and updating 26 and 2 systematic reviews, respectively. Subsequently, consensus was reached on 38 recommendations for preoperative screening, candidate selection, intraoperative quality control, operating principles, postoperative monitoring, and complication management. For KLEx, an effective and accurate refractive correction is attributed to various factors such as corneal thickness, degree of myopia, treatment nomogram, and optical zone. For KLEx-related complications that could affect vision, comprehensive and effective management strategies were proposed, particularly for wrong-plane dissection and difficult lenticule removal, suction loss, and perioperative infection. Customized surgical planning protocols and operative techniques were analyzed. Among all recommendations, 29 (76%) were labelled as "strong", each externally reviewed. The assessment of corneal biomechanical properties may help improve safety and predictability, though needing further validation. The development process also revealed several research gaps for enhancing KLEx safety. These guidelines provide evidence-based recommendations for KLEx in clinical practice, such as on preoperative screening for keratoconus, surgical planning, managements and prevention of complications and infection. The guidelines are expected to improve the safe and effective application of KLEx procedures and achieve more satisfactory visual correction.

Vision corrections used by presbyopic orienteers

SIGNIFICANCE Evaluating the visual challenges and refractive correction solutions of presbyopic orienteers identifies features of relevance to optometric management of the visual needs of active presbyopes. PURPOSE Orienteering is a unique sport requiring visual clarity at a range of viewing distances and has a high proportion of presbyopic participants. This study evaluates the vision corrections used by presbyopic orienteers, specifically aiming to characterize the prevalence of different vision correction options used and to explore the strengths and limitations of different vision correction solutions. METHODS Orienteers 40 years or older completed an online questionnaire consisting of multiple-choice questions covering personal demographics, orienteering participation, and visual corrections worn in everyday life and for orienteering. Free-text questions asked for further information about the corrections used and advice received from eye care practitioners were analyzed using content analysis. RESULTS There were 469 respondents (195 women, 274 men; median age category, 55 to 59 years). For the 187 people without distance refractive correction, the most frequent corrections for orienteering were “off the shelf” reading spectacles (n = 95) or use of a compass magnifier (n = 24), and for the 277 people with distance refractive correction, they were progressive addition spectacles (n = 96) and monovision contact lenses (n = 63). The main visual challenges faced by orienteers were seeing map detail, lens obstruction from fogging and rain, and difficulty orienteering in low light in the daytime. An ideal correction needed to provide visual clarity for both map and terrain. No visual correction type consistently addressed all challenges. Orienteers valued personalized discussion with eye care practitioners to address their needs. CONCLUSIONS Optimal visual corrections for presbyopic orienteers are individual, but higher reading additions to clarify map detail, contact lenses to avoid lens obstruction, additional light, and solutions that provide clear vision at all viewing distances while avoiding the reading add blurring the ground at the orienteer's feet should be considered. Personalized care is necessary to optimize visual correction solutions.

Refractive and ocular motor status in autistic adults without learning disabilities: an exploratory study

ABSTRACT Clinical relevance Refractive and ocular motor anomalies may be more prevalent among autistic adults without learning disabilities, compared to a non-autistic clinical population. In line with current guidance, optometrists should exclude these anomalies prior to prescribing tinted lenses. Background Autistic adults report various visual experiences with largely negative consequences on daily living. Some of these overlap with symptoms of refractive and ocular motor anomalies. Therefore, this study investigated refractive and ocular motor status, and pattern glare, in autistic adults without learning disabilities. The impact of appropriate treatment on visual experiences was explored. Methods Twenty four autistic adults, aged 19–67 years, underwent an eye examination involving refraction, ocular motor and pattern glare assessments. Based on pre-determined criteria, anomalies were treated with spectacles, orthoptic exercises, or tinted lenses. Participants completed three questionnaires (Glasgow Sensory Questionnaire, Visual Function Index and Convergence Insufficiency Symptoms Survey) at the start and end of the study to assess the impact of treatment. Results Relative to population norms, a notable proportion of participants had: a significant change in refractive correction (83.3%); accommodative infacility (72.7%); convergence insufficiency (37.5%); uncompensated distance dissociated heterophoria (33.3%); significant accommodative inaccuracy (27.2%); and positive pattern glare (25%). All participants required treatment. 16.7% were given orthoptic exercises only. New spectacles were dispensed to 79.2%, followed by 16.7% requiring orthoptic exercises and 4.2% dispensed tinted lenses. Questionnaire scores did not significantly change post-treatment. Conclusion This exploratory study suggests autistic adults may be more likely to present with refractive, ocular motor and pattern glare issues. Impacts on autistic visual sensory experiences, vision-related quality of life and visual function remain unclear. Pattern Glare Test scores of autistic adults appear to be reduced by appropriate refractive and/or ocular motor management. Therefore, optometrists should take a conservative approach, managing refraction and ocular motor status of autistic patients prior to considering tinted lenses.

Viewing distance, font size and symptoms of eyestrain in non-presbyopic and presbyopic smartphone users.

Smartphones are the most frequently used digital devices globally with ~6.80 billion users. Despite the ubiquitous use of smartphones, limited information is known on the preferred viewing distance and font size of smartphone users. This study investigated viewing distance, font sizeand symptoms of eyestrain in non-presbyopic and presbyopic smartphone users. In this quantitative research study, viewing distance and font size were measured in a group of non-presbyopes (n = 107) and presbyopes (n = 53), whilst participants viewed a text message and a web page on their own smartphone. Subjects also responded to a verbal questionnaire related to the characteristics of their smartphone and the computer vision syndrome questionnaire to assess symptoms of eyestrain. Data were analysed using descriptive and inferential statistics. For the total sample, the mean viewing distance for a text message was 37.13 ± 8.82 cm (median 36.00 cm), and for a web page was 36.11 ± 7.98 cm (median 36.00 cm). Presbyopes had longer median viewing distances compared with non-presbyopes for a text message (41 cm vs. 34 cm, p < 0.001) and web page (40 cm vs. 34 cm, p < 0.001). The font size for non-presbyopes were <1.0 M whilst for presbyopes were >1.2 M. More than twice the percentage of non-presbyopes were classified with digital eyestrain (DES) compared with presbyopes. Non-presbyopes used shorter viewing distances, smaller font sizes and were more predisposed to DES than presbyopes. The viewing distances adopted by presbyopes were similar to the conventional near-working distance of 40 cm. Eye care practitioners should consider viewing distances when assessing near-visual functions and prescribing a near refractive correction, particularly in non-presbyopes. There should be greater awareness of the importance of adopting appropriate viewing distances when using smartphones.

Refractive blur’s influence on discomfort glare perception from white LED headlights at night

This study examined the effects of refractive blur on discomfort perception caused by peripheral glare from white LED passing (low)-beam headlights at night. The study compared two levels of binocular blur (+0.50 diopter [D] and +1.00D) against a baseline of optimal refractive correction. Thirty participants (mean age 21.3±1.6 years; range 20–24 years) simulating a driving position assessed discomfort from glare sources (headlights of oncoming vehicles) located at 40 and 20 m distances using the de Boer scale. The study found that, with a blur of +0.50D, discomfort glare from white LED headlights did not significantly differ from the baseline regarding de Boer scores. However, with a blur of +1.00D, de Boer scores significantly decreased, indicating increased discomfort glare compared with the baseline for all distances (P=0.004). These results suggest that refractive blur may contribute to an increased perception of discomfort glare during nighttime driving.

Prevalence and association of uncorrected refractive error among Chinese adolescents: a cross-sectional study.

Uncorrected refractive error (URE) is one of the main causes of visual impairments. URE may reduce interaction and learning in the classroom, leading to social isolation, irreversible amblyopia, lack of external knowledge, and restrictions on education and employment opportunities. Our aim was to investigate the prevalence and related factors of URE in adolescents using epidemiological surveys and questionnaire surveys related to lifestyle habits. A cross-sectional school-based study was conducted in Nantong, China, including adolescents 12-19 years of age from 16 schools. URE was defined as presenting visual acuity worse than 6/12 and improving to ≥ 1 lines after correction in either eye. Univariate and multivariate logistic regression analyses were used to investigate specific correlations between URE and related lifestyle parameters. Non-cycloplegic autorefraction was assessed for each adolescent. A total of 2,910 adolescents were analyzed, of which 50.3% (n = 1,465) were male, and 49.7% (n = 1,445) were female. The mean age was 15.23 ± 1.77 years. The overall prevalence of URE was 23.7%. The total prevalence of REC and eREC was 85.1% and 71.7%, respectively, and both of them showed an increasing trend with age (Ptrend = 0.018 and Ptrend = 0.019, respectively). A higher prevalence of URE was related to myopia, anisometropia, and increased daily use of electronic products. Timely visual examination by medical institutions, more extracurricular homework, and older age were protective factors for URE. Among the 689 adolescents with URE, 362 (52.5%) did not receive any refractive correction, and 327 (47.5%) used corrected glasses. URE was highly prevalent among adolescents in China. Myopia was the most important risk factor for URE. The impact of anisometropia and increased daily use of electronic devices on URE was significant. Timely visual examinations by medical institutions served as an effective protective factor against URE. Further research on adjusting intervention strategies is therefore needed to eliminate preventable visual impairments.

3D Modelling and Measuring Dam System of a Pellucid Tufa Lake Using UAV Digital Photogrammetry

The acquisition of the three-dimensional (3D) morphology of the complete tufa dam system is of great significance for analyzing the formation and development of a pellucid tufa lake in a fluvial tufa valley. The dam system is usually composed of the dams partially exposed above-water and the ones totally submerged underwater. This situation makes it difficult to directly obtain the real 3D scene of the dam system solely using an existing measurement technique. In recent years, unmanned aerial vehicle (UAV) digital photogrammetry has been increasingly used to acquire high-precision 3D models of various earth surface scenes. In this study, taking Wolong Lake and its neighborhood in Jiuzhaigou Valley, China as the study site, we employed a fixed-wing UAV equipped with a consumer-level digital camera to capture the overlapping images, and produced the initial Digital Surface Model (DSM) of the dam system. The refraction correction was applied to retrieving the underwater Digital Elevation Model (DEM) of the submerged dam or dam part, and the ground interpolation was adopted to eliminate vegetation obstruction to obtain the DEM of the dam parts above-water. Based on the complete 3D model of the dam system, the elevation profiles along the centerlines of Wolong Lake were derived, and the dimension data of those tufa dams on the section lines were accurately measured. In combination of local hydrodynamics, the implication of the morphological characteristics for analyzing the formation and development of the tufa dam system was also explored.

Effect of Fresnel prism in small-angle esotropia (≤ 20 prism diopters) with fixation preference.

We aimed to investigate the effects of Fresnel prism treatment for small-angle esotropia (≤ 20 prism diopters [PD]) with fixation preference. We included 32 patients with remaining esotropia ≤ 20 PD measured using the simultaneous prism and cover test (SPCT) after full refractive error correction. Fresnel prism was applied to make patients orthotropic with glasses. Treatment was discontinued if remaining esotropia ≤ 4 PD was sustained during two consecutive follow-ups (2-month intervals) or if the angle continued to increase with prism adaptation. Patients were divided into treatment success and failure groups. Treatment success was defined by motor and visual acuity (VA) aspects. Criteria for motor success was residual esotropia ≤ 8 PD in patients with initial esotropia > 8 PD and a 30% decrease of esotropia in those with initial esotropia ≤ 8 PD. VA success was improvement of > 0.2 logMAR in the non-dominant eye. The initial esodeviation angle was 6.92 ± 4.66 PD at distance and 10.53 ± 5.58 at near. The logMAR VA was 0.10 ± 0.13 and 0.26 ± 0.20 in the dominant and non-dominant eye, respectively. Among the 32 patients, 14 showed motor success. Among 26 patients whose VA could be measured, 15 showed VA success. Factors influencing motor success were a small amount of maximum prescribed Fresnel prism, less frequent need for Fresnel prism adaptation, and high percentage of achieving orthotropia with Fresnel prism treatment. VA success was influenced by low frequency of anisometropia and the small amount of maximum prescribed Fresnel prism. Fresnel prism could be a non-invasive treatment option for some patients with small-angle esotropia with fixation preference. What is known The optimal approach for addressing small-angle esotropia is a topic of debate. Not much research has been conducted on Fresnel prism treatment in patients with small-angle esotropia. What is new Motor success and visual acuity improvement were observed in some patients undergoing Fresnel prism treatment. Factors contributing to motor success were the small maximum angle of esodeviation, the less frequent necessity for Fresnel prism adaptation, and the achievement of orthotropia during Fresnel prism treatment. Visual acuity improvement was hindered by the presence of anisometropia and thelarge maximum prescribed amount of Fresnel prism. Fresnel prism treatment can be used as a treatment option for some patients with small-angle esotropia with fixation preference.

Multiphoton scaling of femtosecond laser-induced refractive index change (LIRIC) in hydrogels and rabbit cornea.

To find optimal conditions for performing laser induced refractive index change (LIRIC) in living eyes with both safety and efficacy, we investigated multiphoton excitation scaling of this procedure in hydrogel and excised corneal tissue. Three distinct wavelength modalities were examined: high-repetition-rate (HRR) and low-repetition-rate (LRR) 405 nm systems, as well as 800 nm and 1035 nm systems, whose LIRIC-inducing properties are described for the first time. Of all the systems, LRR 405 nm-LIRIC was able to produce the highest phase shifts at the lowest average laser powers. Relative merits and drawbacks to each modality are discussed as they relate to future efforts towards LIRIC-based refractive error correction in humans.

Unforeseen challenge: bilateral, spontaneous, symmetrical displacement of toric implantable collamer lens: case report

Introduction: The phakic intraocular lenses represent a significant advancement in refractive correction particularly in patients for whom conventional procedures such as laser in situ keratomileusis (LASIK) are contraindicated. To our knowledge, although studies have extensively documented the occurrence and management of implantable collamer lens (ICL) rotation, spontaneous displacement of the ICL has not yet been documented. In this article, we present an interesting case of bilateral ICL displacement. Patient and Clinical Findings: After undergoing bilateral ICL surgery, the patient presented with blurring of vision the next day. On examination, there was symmetrical bilateral displacement of the ICL despite having implanted the maximum size of this lens. Diagnosis, Intervention, and Outcomes: After discussion and analysis, a bilateral explantation of the ICL was performed. Conclusions: Despite taking into consideration all the essential anterior segment parameters for ICL size calculation, there can still be a possibility of ICL displacement.

Development and Validation of a Novel Night-Time Hazard Visibility Test.

Night-time driving is dangerous, with increased crash rates, particularly involving vulnerable road users. A Night-Time Hazard Visibility Test (NHVT) was developed and validated by exploring the effects of refractive and cataract blur on performance. The NHVT comprised video clips of night-time roads from the driver's perspective, including different hazards (pedestrians, cyclists, and vehicles). Participants responded when they first recognized hazards requiring them to take evasive action to avoid a collision. In experiment 1, there were 16 young visually normal drivers (mean age = 22.3, standard deviation [SD] = 2.2 years) who completed 2 NHVT sets, viewed separately through best-correction and refractive blur (+1.00 diopter sphere [DS]). In experiment 2, a refined version of the NHVT was administered to an additional 16 young visually normal drivers (mean age = 21.1, SD = 1.2 years) with best-correction and cataract blur. The order of visual conditions and NHVT sets were counterbalanced. In experiment 1, refractive blur significantly reduced photopic visual acuity (VA) compared to best-corrected vision (+0.09 vs. -0.21 logMAR, P < 0.001) and delayed response times by 0.69 seconds (3.10 vs. 2.41 seconds, P < 0.001) compared to best-corrected vision. In experiment 2, cataract blur reduced VA compared to best-corrected vision (+0.03 vs. -0.17 logMAR, P < 0.001) and delayed response times by 0.63 seconds (2.92 vs. 2.29 seconds, P < 0.001). The NHVT was sensitive to refractive and cataract blur, providing preliminary support of its validity as a measure of night-time hazard visibility performance. The NHVT has potential as an off-road assessment of visibility for night driving and application for assessment of drivers with different refractive corrections and ocular diseases.

Corneal Epithelial Remodeling Following Cylinder Correction With SMILE or FS-LASIK: A Contralateral Comparative Study.

To compare the corneal epithelial remodeling in eyes with high astigmatism that had small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Seventy-four patients with myopic astigmatism of greater than -2.00 diopters (D) and little binocular difference in spherical equivalent were included in this contralateral comparative study. All patients received SMILE in one eye and FS-LASIK in the other eye randomly. The corneal epithelial remodeling pattern was mapped using the latest RTVue spectral-domain optical coherence tomographer (Optovue) by region. Satisfactory refractive correction was achieved in all enrolled eyes with either SMILE or FS-LASIK. The corneal epithelium gradually thickened following surgical cylinder correction, distributing mainly along the flat medium. The corneal epithelium proliferation is milder centrally but more pronounced in the mid-peripheral area after SMILE, compared with FS-LASIK. The flat-steep difference in corneal epithelial thickness (CET) is evident in the mid-peripheral and peripheral areas, which is more obvious in SMILE. Residual cylinder was positively correlated with CET in eyes that had FS-LASIK, but not SMILE. More importantly, these epithelial changes were positively correlated with the ablation depth and higher order aberrations following surgical refractive correction. The postoperative CET map varied between SMILE and FS-LASIK. In eyes with high astigmatism, SMILE surgery is followed by milder and more stable corneal epithelial thickening. Moreover, the corneal epithelium is sensitive to stromal ablation and corneal remodeling is crucial to the postoperative visual quality. This study rigorously distinguished the CET difference between SMILE and FS-LASIK in astigmatic eyes and shed light on subsequent research. [J Refract Surg. 2024;40(10);e728-e741.].

Development, Validity, and Reliability of the Primary Eye Care Questionnaire (PECQ) Among Optometrists in Malaysia.

Visual impairment and vision loss are preventable or treatable if there is access to eyecare services for early detection and if proper interventions are given.Optometristsplay a vital role in the early detection of eye and visual-related issues.As healthcare professionals, optometrists are trained to provide comprehensive eye and vision care encompassing dispensing and refraction, detection of abnormalities in the vision and eye, and the rehabilitation of conditions of the visual system, as suggested by the World Council of Optometry.In the current practice of primary eye care, optometrists are not fully utilized and are mostly restricted to refractive correction. Therefore, the optometrists' practice level, scope, and challenges to practice primary eye care must be identified before strengthening optometrists' role in the community. The present study aimed to develop and validate a questionnaireto determine the contributing factors and challenges to the practice of primary eye care by optometrists in Malaysia. The Primary Eye Care Questionnaire (PECQ) was developed through an extensive literature search to identify the domains and to construct the items. The items were then scrutinized further through focus group discussions with experts (n = 10) from various sectors of eye care. Content validation was conducted with ophthalmologists and optometrists as panels (n = 10), followed by face validation (n = 10) by optometrists from the public and private sectors. Construct validation was performed with exploratory factor analysis and reliability was evaluated by using Cronbach's alpha coefficient and the test-retest reliability. In total, the PECQ questionnaire was constructed with 123 itemsunder three main domains: contributing factors, challenges, and continuous education. The content validity index (CVI) for each item (I-CVI) score ranged from 0.9 to 1.0 for each item and the CVI for average scale (S-CVI/Ave) was above 0.8 for each domain, with internal consistency of 0.948 and Cronbach's alpha coefficient of 0.971. The PECQ is a valid and reliable tool for assessing the optometrists' scope of practice, challenges, and contributing factors to the practice of primary eye care.