Assessing the role of visual dysfunctions in the association between visual symptomatology and the use of digital devices / Evaluación del papel de las disfunciones visuales en la asociación entre la sintomatología visual y el uso de dispositivos digitales

Purpose: To evaluate the association between visual symptoms and use of digital devices considering the presence of visual dysfunctions. Methods: An optometric examination was conducted in a clinical sample of 346 patients to diagnose any type of visual anomaly. Visual symptoms were collected using the validated SQVD questionnaire. A threshold of 6 hours per day was used to quantify the effects of digital device usage and patients were divided into two groups: under and above of 35 years old. A multivariate logistic regression was employed to investigate the association between digital device use and symptoms, with visual dysfunctions considered as a confounding variable. Crude and the adjusted odds ratio (OR) were calculated for each variable. Results: 57.02 % of the subjects reported visual symptoms, and 65.02% exhibited some form of visual dysfunction. For patients under 35 years old, an association was found between having visual symptoms and digital device use (OR = 2.10, p = 0.01). However, after adjusting for visual dysfunctions, this association disappeared (OR = 1.44, p = 0.27) and the association was instead between symptoms and refractive dysfunction (OR = 6.52, p < 0.001), accommodative (OR = 10.47, p < 0.001), binocular (OR = 6.68, p < 0.001) and accommodative plus binocular dysfunctions (OR = 46.84, p < 0.001). Among patients over 35 years old, no association was found between symptoms and the use of digital devices (OR = 1.27, p = 0.49) but there was an association between symptoms and refractive dysfunction (OR = 3.54, p = 0.001). Conclusions: Visual symptoms are not dependent on the duration of digital device use but rather on the presence of any type of visual dysfunction: refractive, accommodative and/or binocular one, which should be diagnosed.(AU)

Clinical Evaluation of a New Spectral-Domain Optical Coherence Tomography-Based Biometer.

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

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.

Causes of intraocular pseudophakic lens explantation in Spain.

PURPOSE: To report the causes of pseudophakic intraocular lens (IOL) explantation in Spain over a 20 year period. METHODS: Multicenter observational prospective study of a consecutive series of cases corresponding to pseudophakic intraocular lenses explantations performed in 22 Spanish clinical centres from 2002 to 2021, within a national clinical research network. The clinical data of all IOL explantation patients was evaluated, and the different causes for IOL explantation were systematically analyzed. RESULTS: From a total of 1013 pseudophakic explantations, 919 cases were included in this investigation. The mean age of the patients at the time of explantation was 66.3 years, and 142 (15.45%) were women. Over the 20 years of the study, the five main reasons for explanting lenses in the last 20 years in Spain according to the Iberia RETICS database were: dislocation / decentration / misalignment (43.08%), bullous keratopathy (16.79%), neuroadaptation failure (13.85%), IOL opacification (9.71%), refractive surprise (6.87%). Other causes, less frequent, were uveitis / endophthalmitis / infection with 39 cases (4.25%); IOL substitution for reasons other than multifocal IOL neuroadaptation failure 3 cases (0.33%); and other causes, 47 cases (5.13%). Hydrophobic lenses were the most frequently explanted with a ratio of 47.1%. CONCLUSIONS: Over the 20 years of the study, the five main reasons for explanting lenses in the last 20 years in Spain according to the Iberia RETICS database were: dislocation / decentration / misalignment, bullous keratopathy, neuroadaptation failure, IOL opacification, and refractive surprise.

Assessing the role of visual dysfunctions in the association between visual symptomatology and the use of digital devices.

PURPOSE: To evaluate the association between visual symptoms and use of digital devices considering the presence of visual dysfunctions. METHODS: An optometric examination was conducted in a clinical sample of 346 patients to diagnose any type of visual anomaly. Visual symptoms were collected using the validated SQVD questionnaire. A threshold of 6 hours per day was used to quantify the effects of digital device usage and patients were divided into two groups: under and above of 35 years old. A multivariate logistic regression was employed to investigate the association between digital device use and symptoms, with visual dysfunctions considered as a confounding variable. Crude and the adjusted odds ratio (OR) were calculated for each variable. RESULTS: 57.02 % of the subjects reported visual symptoms, and 65.02% exhibited some form of visual dysfunction. For patients under 35 years old, an association was found between having visual symptoms and digital device use (OR = 2.10, p = 0.01). However, after adjusting for visual dysfunctions, this association disappeared (OR = 1.44, p = 0.27) and the association was instead between symptoms and refractive dysfunction (OR = 6.52, p < 0.001), accommodative (OR = 10.47, p < 0.001), binocular (OR = 6.68, p < 0.001) and accommodative plus binocular dysfunctions (OR = 46.84, p < 0.001). Among patients over 35 years old, no association was found between symptoms and the use of digital devices (OR = 1.27, p = 0.49) but there was an association between symptoms and refractive dysfunction (OR = 3.54, p = 0.001). CONCLUSIONS: Visual symptoms are not dependent on the duration of digital device use but rather on the presence of any type of visual dysfunction: refractive, accommodative and/or binocular one, which should be diagnosed.

Comparative Analysis of Strabismus Measurement Using a Video Oculagraphy System and Alternate Prism Cover Test.

PURPOSE: The aim of the study was to compare distance vision measurements obtained with video oculography (VOG) and an alternate prism cover test (APCT). DESIGN: Single-center, retrospective, and cross-sectional. METHODS: Eighty-seven subjects with strabismus were included. All patients underwent an optometric examination. The measurement of strabismus in distance vision was performed with the best optical correction using the APCT and the VOG GazeLab. Subjects were divided according to the type of strabismus; 41 were esotropic and 46 were exotropic. RESULTS: The general comparison of APCT and VOG showed a mean difference of 0.60±2.74 prism diopters (Δ), not observing statistical differences between both methods ( P =0.059) and presenting a correlation of 0.976 ( P <0.001). Using APCT, the mean amount of esotropia for the group was 18.31±11.64 Δ and that of exotropia was 19.62±8.80 Δ. Compared with the VOG, the mean value of esotropia for the group was 18.65±11.65 Δ and that of exotropia was 19.48±8.62 Δ. The means are statistically different for the esotropia group ( P =0.005) but not for the exotropia group ( P =0.318). There was a high direct correlation between the methods of measurement for both the esotropic ( R =0.980; P <0.001) and exotropic patients ( R =0.975; P <0.001). Bland-Altman analysis shows a mean difference of 1.37±2.76 Δ for the esotropia patients and 0.31±2.66 Δ for the exotropic patients, respectively. CONCLUSIONS: This study demonstrated comparable results in measuring strabismus between VOG and APTC for esotropia and exotropia, with an excellent correlation between both methods and good agreement, especially in subjects with exotropia.

FS-LASIK for the treatment of moderate-to-high hyperopia.

PURPOSE: To report modern outcomes of femtosecond laser-assisted cataract surgery (FS-LASIK) for the correction of moderate-to-high hyperopia (≥3.50 diopters [D] and ≤6.50 D), excluding low or very high hyperopia. SETTING: Vissum, Alicante, Spain. DESIGN: Monocentric retrospective case series study. METHODS: Visumax-500 kHz femtosecond laser and Amaris-750 excimer-laser were used. Eyes with at least 6 months of follow-up were included. 36-month data was collected when available. Primary outcome measure was short term efficacy and safety. Secondary outcome measure was long term stability. RESULTS: 6-month data of 92 eyes was collected (68 eyes at 36 months). Mean age was 34.6 ± 10.4 years. Mean treated sphere was 4.69 ± 0.87. Efficacy index was 0.91 and 0.90 at 6 months and 36 months respectively. Safety index was 1.00. Uncorrected distance visual acuity was 20/20 or better in 72%, postoperative spherical equivalent within 0.5 D in 80% (93% within 1 D), and loss of 1 line of corrected distance visual acuity (CDVA) occurred in 13% (2 or more lines in 0%). Gain of 1 or more CDVA lines occurred in 17%. A slight but significant regression was observed at 36 months. Postoperatively, 21.73% required flap lift for laser enhancement, and 11.95% an orthoptic visual rehabilitation due to accommodative disorders. CONCLUSIONS: Modern LASIK provides good efficacy and safety levels for the management of moderate to high hyperopia (up to +6.5 D), with levels close to those previously reported with refractive lens exchange for young hyperopia patients without presbyopia, where we defend the maintenance of LASIK as first line therapy. Risk of requiring a refractive enhancement or an orthoptic visual rehabilitation remains relevant and needs to be discussed with patients preoperatively.

Bilensectomy: Safety and Visual Outcomes in Angle-Supported, Iris-Fixated, and Posterior Chamber Phakic Intraocular Lenses.

PURPOSE: To report the visual and refractive outcomes, intraoperative and postoperative complications, and main causes of bilensectomy in the different types of phakic intraocular lenses (pIOLs). METHODS: This was a retrospective multicenter study that included 234 eyes of 185 patients that underwent bilensectomy. Patients were divided into three groups depending on the pIOL that was explanted (angle-supported, iris-fixated, or posterior chamber). The main reasons leading to the indication for bilensectomy, time elapsed between pIOL implantation and bilensectomy, intraoperative and postoperative complications, uncorrected and corrected distance visual acuity (UDVA and CDVA), and endothelial cell density loss 1 year after bilensectomy were evaluated. RESULTS: There was a statistically significant improvement in UDVA and CDVA after bilensectomy in all groups. Cataract development was the main reason for bilensectomy, followed by significant endothelial cell density loss. Time between pIOL implantation and bilensectomy was significantly greater in eyes with an anterior chamber pIOL. CONCLUSIONS: Bilensectomy outcomes in general are good. Iris-fixated lenses, particularly hyperopic, are more prone to intraoperative complications and endothelial cell loss than the other pIOLs models. The results show that bilensectomy is a safe and effective procedure with a relatively low rate of intraoperative and postoperative complications and acceptable refractive predictability. [J Refract Surg. 2023;39(3):128-134.].

Efficacy and safety of intense pulsed light direct eyelid application.

To describe the efficacy and safety of intense pulsed light (IPL) applied directly on the eyelids of patients with Meibomian gland dysfunction (MGD) without corneal shield protector. Observational retrospective single centre study where patients underwent 3 treatment sessions of IPL with 2 weeks of interval. The IPL was carried out with Lumenis OPT M22 with a double pass technique of 12 impacts on the infraorbital/lower eyelid region with the 15 × 35 mm guide light (step 1) and a double pass technique of 3 impacts over the upper eyelids with the 8 × 15 mm guide light (step 2). The follow up was conducted through Oculus Keratograph 5 M. 30 patients were enrolled in the study. Although there were no significant differences (p > 0.05), non-invasive tear break-up time, ocular redness, and OSDI questionnaire improved during the 3 IPL sessions. A significant improvement (p = 0.024) in the percentage of meibomian gland loss was also observed. Regarding tear meniscus, it was found similar measurements before and after treatment. No serious adverse effects were reported during the procedure or in subsequent follow-up. Preliminary results suggest that IPL therapy applied directly on the eyelids without corneal shield could be safe and effective in the treatment of MGD.

Corneal Epithelium Thickness and Refractive Changes After Myopic Laser Corneal Refractive Surgery.

PURPOSE: To evaluate the postoperative changes in corneal epithelium thickness and refractive power after femtosecond laser-assisted laser in situ keratomileusis (LASIK) and small incision lenticule extraction (SMILE) for myopia correction using anterior segment optical coherence tomography (OCT) with an integrated Placido disc topographer. METHODS: The VisuMax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) and Amaris 750 excimer laser (SCHWIND eye-tech-solutions) were used. Central, paracentral, and 6-mm epithelial thickness values were obtained, and the change in the value of epithelial thickness was calculated. Changes in the refractive power of the epithelium were also evaluated. The repeatability of this new measurement was also analyzed using the intraclass correlation (ICC). The total follow-up period was 6 months. RESULTS: A total of 77 LASIK eyes were matched with 77 SMILE eyes. Mean spherical equivalent was -3.92 ± 1.67 diopters (D) for LASIK versus -4.02 ± 1.63 D for SMILE (P = .356). Epithelial thickness parameters significantly and equally thickened in both types of surgery. The change in the value of epithelial thickness was positively correlated with spherical aberration. Analysis of the refractive power of the corneal epithelial layer (ICC > 0.70) showed a tendency for the postoperative myopization of the refractive component of this layer (-0.11 D for SMILE and -0.53 D for LASIK at 3 mm) and an increase in its cylinder and aberrometry. Increasing postoperative spherical aberration and epithelial thickness increased myopization of the epithelial refractive sphere (P < .05). CONCLUSIONS: Corneal epithelium thickens similarly after LASIK and SMILE, being slightly higher after SMILE. This correlates with the induced spherical aberration. Corneal epithelium thickening induces myopization of its refractive power, which accounts for a slight regression of the net refractive power change on the treated cornea. [J Refract Surg. 2022;38(9):602-608.].

Patients' dissatisfaction with multifocal intraocular lenses managed by exchange with other multifocal lenses of different optical profiles.

BACKGROUND: The aim of the study was to evaluate the outcomes of dissatisfied patients reporting poor visual quality following implantation of multifocal intraocular lenses (MF-IOLs), managed by IOL exchange with another multifocal optical profile. METHODS: This is a retrospective series of cases. MF-IOL exchange was done in 15 dissatisfied patients (30 eyes) with the perception of poor visual quality for far distance affected by neuroadaptation failure. Patients underwent a bilateral exchange of a MF-IOL with another MF-IOL of a different optical profile. Visual outcomes and complications were analyzed. Questionnaires including Quality of Vision (QoV), Visual Function Index-14 (VF-14) and its Rasch-revised version (VF-8R) and a satisfaction questionnaire were also used for outcome evaluation. RESULTS: The mean elapsed time from implantation to explantation-reimplantation was 11.8 months. The QoV scores improved significantly across all the three subscales. Visual function improved with a change in VF-14 score from 60.41 ± 24.81 to 90.16 ± 10.91 (P < 0.001). The VF-8R score improved as well. The uncorrected distance visual acuity improved from 0.24 to 0.12 logMAR after exchange (P < 0.001) and corrected distance visual acuity improved from 0.15 to 0.04 logMAR (P < 0.001). Safety and efficacy indexes reached 1.46 and 1.16, respectively. Concerning patients' satisfaction following MF-IOL exchange, 80% of the patients reported they would have the MF-IOL reimplantation procedure again. CONCLUSIONS: Patient dissatisfaction with neuroadaptation failure following MF-IOL implantation can be managed in 80% of our cases by MF-IOL exchange with a different MF-IOL optical profile.

Validation of the Symptom Questionnaire for Visual Dysfunctions (SQVD): A Questionnaire to Evaluate Symptoms of any Type of Visual Dysfunctions.

PURPOSE: To assess psychometric properties of the Symptom Questionnaire for Visual Dysfunctions (SQVD) questionnaire, including accuracy, validity, and reliability, in a clinical sample of patients having any type of visual dysfunction. METHODS: A clinical sample of 306 patients self-administered the SQVD. Rasch analysis was performed to analyze the functionality of the response categories, fit statistics, differential item functioning (DIF), person and item reliability, targeting, local dependency, unidimensionality, and transformation table. Accuracy was assessed by means of receiver operating characteristic (ROC) curves, using symptoms reported in each patient's clinical record as the gold standard for classifying patients with and without symptoms. The concurrent validity, known group validity, and test-retest reliability (repeatability, using the intraclass correlation coefficient [ICC]) were also examined. RESULTS: SQVD showed orderly category responses. The 14 items fit the Rasch model without significant DIF for gender, presbyopia, and dysfunctions. Person and item reliabilities were 0.81 and 0.85, respectively. Targeting was -1.49 logits. Yen's Q3 statistic showed no local dependency. SQVD was unidimensional (first contrast of the residual = 1.852 eigenvalue with a variance explained by measures of 52.23%). The area under the ROC curve was 0.836 (95% confidence interval [CI], 0.792-0.879) with a cutoff of ≥6 showing good accuracy (sensitivity = 0.759; specificity = 0.783). SQVD showed good concurrent and known group validity and high repeatability (ICC, 0.857; 95% CI, 0.710-0.933) when administered twice 1 week apart. CONCLUSIONS: SQVD has shown good psychometric properties. It can be considered an accurate, valid, and reliable questionnaire to detect visual symptoms related to any type of refractive, accommodative, and binocular dysfunction. TRANSLATIONAL RELEVANCE: SQVD may be used for diagnostic purposes, as it can accurately detect symptoms related to any sort of visual dysfunction. It may also be useful to monitor the treatment outcomes of these conditions.

Comparison of the Cost-Effectiveness of SMILE, FS-LASIK, and PRK for Myopia in a Private Eye Center in Spain.

PURPOSE: To describe and compare the cost-effectiveness of small incision lenticule extraction (SMILE), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and photorefractive keratectomy (PRK) for treating myopia and myopic astigmatism in a private eye center. METHODS: The perspectives for this cost-effectiveness analysis were for the payer and the health care sector. For the payer's perspective, a decision tree model was made, with a time period of 30 years, and the average weighted utility values and quality-adjusted life years (QALY) were computed for each procedure. The average weighted costs were derived for each procedure and divided by the QALY to obtain the incremental cost-effectiveness ratios (ICER). For the health care sector's perspective, the direct and indirect costs of acquiring the equipment and maintaining the facilities-including consumables and personnel salaries-were obtained to compute the minimum number of patients treated per year. RESULTS: The weighted utility values were 0.8 for SMILE and PRK and 0.77 for FS-LASIK. The weighted QALYs were 24 for SMILE and PRK, and 23.1 for FS-LASIK. The average weighted costs were 335.45, 443, and 346.96€, respectively. The resulting incremental cost-effectiveness ratios were 13.98 €/QALY for SMILE, 18.46 €/QALY for PRK, and 15.02 €/QALY for FS-LASIK. There was a negative correlation between the ICER and the time (in years) after the surgery. To achieve a profit, the minimum number of patients treated per year is 155 for SMILE, 136 for PRK, and 155 for FS-LASIK. CONCLUSIONS: Laser corneal refractive surgery is cost-effective for a person desirous of refractive correction for myopia. SMILE had the lowest ICER, followed by FS-LASIK and PRK. This trend was noted at all time periods. The cost of investing in laser refractive surgery facilities is outweighed by the potential income in high-volume eye centers. [J Refract Surg. 2022;38(1):21-26.].

Corneal stromal thickness changes after myopic laser corneal refractive surgery.

PURPOSE: To evaluate the postoperative behavior of the central corneal stromal thickness after myopic femto-laser-assisted in-situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) by using combined anterior segment optical coherence tomography and a Placido disk topographer and to compare the accuracy of both laser machines in predicting the real stromal change. SETTING: Vissum Miranza, Alicante, Spain. STUDY DESIGN: Prospective, observational, comparative study. METHODS: The VisuMax 500 kHz femtosecond laser (FS) and the Amaris 750 excimer laser were used for the correction of myopia with or without myopic astigmatism. Central and paracentral stromal thicknesses (ST) and 6.0 mm corneal aberrometry were obtained with the MS39 topographer. Laser-predicted stromal consumption was recorded (maximum lenticule thickness for SMILE and central ablation depth for LASIK). Visual and refractive outcomes were also evaluated. Total follow-up was 6 months. RESULTS: 77 LASIK eyes were matched with 77 SMILE eyes. Mean preoperative spherical equivalent (SE) was -3.92 ± 1.67 diopters (D) for LASIK and -4.02 ± 1.63 D for SMILE (P = .356). After LASIK, ST parameters showed significant rethickening between months 1 and 3 (+4.38 µm for central ST; P < .001), remaining stable thereafter. After SMILE, all ST parameters remained stable from month 1. Stromal ablation prediction was higher for SMILE compared with LASIK for all SE ranges, although postoperatively such differences were significant only for ametropias ≤4 D. At 6 months, mean SMILE laser prediction error was -13.21 ± 7.00 µm, whereas LASIK prediction showed better accuracy (+0.92 ± 8.16 µm; P < .001). CONCLUSIONS: The accuracy of the Amaris 750 excimer laser in predicting the stromal consumption after LASIK was better than the VisuMax FS laser for SMILE. Although SMILE ST remained stable from month 1, after LASIK, mild stromal rethickening was observed up to the third month.

Influence of age on small incision lenticule extraction outcomes.

PURPOSE: To evaluate the influence of patient's age at the time of surgery on small incision lenticule extraction (SMILE) refractive outcomes. METHODS: This is a retrospective, consecutive, comparative study. We compared the refractive outcomes after myopic SMILE from two groups of patients divided by age (patients ≤35 and ≥40 years old). All eyes were evaluated preoperatively and at 1 and 6 months postoperatively. Main outcome measures were differences on efficacy, safety, predictability and astigmatic changes by vector analysis with ASSORT software between both study groups. RESULTS: 102 matched eyes of 53 patients were included. Preoperatively, we evidenced no differences in the mean SE or astigmatism between groups. However, 6 months postoperatively we observed a significantly worse mean astigmatism (p=0.019), while not regarding SE, in the older population, with a trend towards undercorrection of the refractive cylinder in the ≥40 group. We also observed a statistically significant difference in the efficacy (0.86-1 month and 0.97-6 months in ≥40group vs 0.97-1 month and 1.07-6 months in the ≤35 group; p=0.003) and safety indexes (0.93-1 month and 1.04-6 months in ≥40 group vs 1.0-1 month and 1.11-6 months in the ≤35 group; p=0.008) at 6 months among groups. CONCLUSIONS: Post-SMILE refractive outcomes in those patients over 40 years of age, although acceptable, are not as good as those obtained in younger patients, showing a significantly lower efficacy and safety indexes, and poorer astigmatic outcomes, with a tendency towards undercorrection. We hypothetise that the increased corneal stroma stiffness in the aged group modifies the post-SMILE corneal stroma remodelling capacity, thus affecting the SMILE refractive and visual response.

Rasch analysis for development and reduction of Symptom Questionnaire for Visual Dysfunctions (SQVD).

To develop the Symptom Questionnaire for Visual Dysfunctions (SQVD) and to perform a psychometric analysis using Rasch method to obtain an instrument which allows to detect the presence and frequency of visual symptoms related to any visual dysfunction. A pilot version of 33 items was carried out on a sample of 125 patients from an optometric clinic. Rasch model (using Andrich Rating Scale Model) was applied to investigate the category probability curves and Andrich thresholds, infit and outfit mean square, local dependency using Yen's Q3 statistic, Differential item functioning (DIF) for gender and presbyopia, person and item reliability, unidimensionality, targeting and ordinal to interval conversion table. Category probability curves suggested to collapse a response category. Rasch analysis reduced the questionnaire from 33 to 14 items. The final SQVD showed that 14 items fit to the model without local dependency and no significant DIF for gender and presbyopia. Person reliability was satisfactory (0.81). The first contrast of the residual was 1.908 eigenvalue, showing unidimensionality and targeting was - 1.59 logits. In general, the SQVD is a well-structured tool which shows that data adequately fit the Rasch model, with adequate psychometric properties, making it a reliable and valid instrument to measure visual symptoms.

Evolution of corneal thickness and optical density after laser in situ keratomileusis versus small incision lenticule extraction for myopia correction.

PURPOSE: To compare the thickness and stromal optical density (OD) evolution of the flap and cap after femtosecond (FS-LASIK; Visumax) and small incision lenticule extraction (SMILE), respectively, for myopia correction. METHODS: A prospective study comprising 78 eyes (n=39 per group) was performed. Anterior segment optical coherence tomography (MS39) images were collected at each postoperative visit (1 day, 1 week and 1 and 3 months) and flap/cap thicknesses were measured. Using ImageJ software, three regions were defined to measure OD (in grayscale units: flap/cap stroma, residual stromal bed (RSB) and all stroma (including flap/cap-stroma, surgical interface and RSB). RESULTS: Mean central thickness significantly increased during the 3-month follow-up in both LASIK (5.43±4.23 µm; p=0.0118) and SMILE (2.76±5.61 µm; p=0.0118), with differences between both techniques statistically significant (p=0.020). All OD values showed a statistically significant reduction during SMILE follow-up: cap 48.96±5.55 versus 44.95±5.41 (p=0.19×10-6), RSB 50.26±7.06 versus 45.42±7.53 (p=0.00005), total stroma 50.34±6.49 versus 45.46±6.96 (p=0.5×10-5) at 1 day and 3 months, respectively, whereas no statistically significant changes were found during LASIK follow-up. No significant differences were observed in OD values between both techniques at any time point, although SMILE showed a tendency for higher OD values than LASIK within the first postoperative month. Visumax presented a tendency for thicker caps than target (11.48±7.85 µm), but not for flaps (2.73±8.93 µm) (p=0.00003). CONCLUSIONS: Both LASIK flaps and SMILE caps show a significant postoperative rethickening. SMILE corneas present higher optical densities than LASIK corneas in the early postoperative period, with a significant decrease thereafter and up to 3 months. These findings correlate with the delayed visual recovery observed after SMILE.

Laser-assisted in situ keratomileusis long term outcomes in late adolescence.

PURPOSE: Evaluate the long term outcomes of myopic-LASIK in a late adolescent population (age ⩾17 and <20 at the time of surgery). METHODS: Monocentric retrospective case series study. Eyes with at least 3 years of follow-up time were included. Primary outcome measures were long term efficacy, safety and stability of the refractive error. Secondary outcome measure was the evaluation of the relation between the postoperative spherical aberration and the long term stability of the refractive error. RESULTS: Forty-seven eyes of 25 patients were included. Mean follow-up was 9.23 ± 3.16 years. Mean age at the time of surgery was 18.74 ± 0.44 years. With time, postoperative UDVA showed a mild but significant deterioration of 1-2 Snellen lines (p = 0.012), in connection with a mild but significant myopization of the SE (mean increase of -0.43 D; p < 0.001), sphere (mean increase of -0.29 D; p = 0.004) and cylinder (mean increase of -0.16 D; p = 0.013). CDVA remained stable over time (p > 0.05). Efficacy index decreased from 1.01 to 0.87 in the long term (77% UDVA ⩾ 20/32). Safety remained at 1.06. 66% and 74% of eyes presented a SE within ±0.50 D and ±1.00 D respectively. SE changed over 0.50D in 33% of eyes. No correlation could be detected between the SE and the postoperative spherical aberration. No cases of corneal ectasia were detected. CONCLUSIONS: Myopic-LASIK in late adolescence is safe and effective, but a mild myopic progression occurs. Despite presence of refractive stability is preferable, if necessary, myopic LASIK provides relatively good outcomes in the long term in this young population.

Delphi methodology for symptomatology associated with visual dysfunctions.

To analyse what eyecare clinicians think about which symptoms are associated with refractive, accommodative and binocular dysfunctions, and which of them should be used in a questionnaire of visual symptomatology. A Delphi method was developed, using a coordinating group and a group of experts, and the process was conducted in three rounds. In the first round we compiled a list of 34 symptoms from the scientific literature and additional 10 suggested by the experts. These symptoms were categorized by each expert to the associated visual anomalies and working distance. In the second round, the relationship between each symptom and visual dysfunctions was analysed using a numeric scale. In the third round, the appearance or absence of the 44 symptoms in a questionnaire was assessed. Symptoms most frequently assigned by the experts to visual anomalies were related to near vision. Symptoms of blurred vision, difficulty focusing from one distance to another and close one eye obtained the highest mean score for refractive, accommodative and binocular disorders respectively. The experts were in agreement for 15 symptoms and in disagreement for 5 symptoms that should appear in a questionnaire. Delphi method has been used to identify the symptoms related to visual dysfunctions according to eyecare professionals and has allowed to arrive at appropriate symptoms to be asked for in a visual symptomatology questionnaire.

Laser flap enhancement 5 to 9 years and 10 or more years after laser in situ keratomileusis: Safety and efficacy.

PURPOSE: To study the safety and efficacy of refractive enhancement by flap lifting 5 and 10 years after laser in situ keratomileusis (LASIK). SETTING: Vissum Alicante, Spain. DESIGN: Retrospective case series. METHODS: Eyes with a flap lift at least 5 years after primary LASIK with a 3-month follow-up were evaluated. The primary outcome measures were safety and the complication rate. Moderate epithelial ingrowth was managed with Nd:YAG laser treatment. RESULTS: The primary LASIK procedure was myopic in 45 eyes, hyperopic in 22 eyes, and presbyopic in 3 eyes. The mean time from primary LASIK to the flap lift was 12.3 years ± 3.45 (SD). In 57 eyes, the primary LASIK flap was created at least 10 years before the enhancement. The mean pre-lift spherical equivalent was -1.29 ± 1.23 diopters (D) in the myopia group and +0.65 ± 1.72 D in the hyperopia group. Three months later, 88% of eyes and 74% of eyes, respectively, had an uncorrected distance visual acuity of 20/20 or better; 100% achieved at least 20/25. No eye lost 2 lines or more of corrected distance visual acuity. In the myopia group, the efficacy index was 0.94 and the safety index was 0.98 at 6 months. Mild epithelial ingrowth developed in 31.43% of eyes and clinically significant epithelial ingrowth in 11.42% of eyes; 4.28% required a relift for severe epithelial ingrowth. CONCLUSIONS: Late flap lift for refractive enhancement 10 years or more after LASIK provided good efficacy and safety with fast visual recovery. The rate of surgical intervention for significant postoperative epithelial ingrowth was low.