Contact lens wear and follow-up and its association with signs and symptoms of meibomian gland dysfunction.

INTRODUCTION: This study investigated the equivocal association between contact lens (CL) wear and meibomian gland dysfunction (MGD) by comparing the morphological, functional and subjective outcomes of CL wearers versus control, non-CL wearers. CL wearers were examined as two cohorts based on the annual attendance of follow-up visits (FLU-attended these visits, whereas non-FLU did not). METHODS: Habitual logMAR visual acuity, invasive and non-invasive tear break-up time, Schirmer test, Efron grading scales, meibum quality score (MQS), meibum expressibility score (MES), meibomian gland (MG) loss, lid margin abnormalities and subjective dry eye (DE) symptoms were assessed. RESULTS: Of the 128 participants, 31 were in the FLU cohort, 43 were in the non-FLU cohort and 54 were controls (mean ages: 22.2 ± 3.1, 23.0 ± 4.6 and 22.3 ± 3.5, respectively). Non-FLU CL wearers had more symptoms than controls (3.7 ± 2.4 vs. 2.3 ± 2.1, p < 0.01). Morphologically, FLU (16.9 ± 8.8%, p = 0.02) and non-FLU (18.6 ± 11.3%, p = 0.001) had more MG loss than controls (11.2 ± 6.8%). Functionally, FLU (0.6 ± 0.7, p = 0.01) and non-FLU (0.8 ± 0.9, p = 0.001) had worse MES than controls (0.2 ± 0.5). FLU and non-FLU were both associated with corneal staining (odds ratio [OR] = 3.42, 95% CI: 1.16-10.11, p = 0.03 and OR = 5.23, 95% CI: 1.89-14.48, p = 0.001, respectively) and MG loss (OR = 10.47, 95% CI: 1.14-96.29, p = 0.04 and OR = 16.63, 95% CI: 1.96-140.86, p = 0.01, respectively). Non-FLU CL wear was also associated with abnormal MQS (OR = 12.87, 95% CI: 1.12-148.41, p = 0.04), conjunctival staining (OR = 12.18, 95% CI: 3.66-40.51, p < 0.001) and lid margin telangiectasia (OR = 3.78, 95% CI: 1.55-9.21, p = 0.003). MGD was three times more prevalent in CL wearers (12%) than in controls (4%). CONCLUSIONS: Both CL-wearing cohorts demonstrated significantly more MG abnormalities than controls though the difference was not clinically significant. Non-FLU CL wearers had more DE symptoms. Non-FLU CL wear is an independent predictor for more abnormalities than FLU CL wear, emphasising the importance of follow-ups.

Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review.

Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment.

Topical review of the relationship between contact lens wear and meibomian gland dysfunction

Contact lens (CL) wearers often suffer from ocular discomfort, which leads to cessation of CL wear. About 30% to 50% of CL wearers complain of dry eye (DE) symptoms. Meibomian gland dysfunction (MGD) is considered the most common cause of evaporative DE. Numerous studies have investigated whether CL wear might affect the meibomian glands. This manuscript reviews studies examining the relationship between CL use and MGD. A PubMed database search was conducted for studies published between 1980-2021 with one or a combination of search terms related to “meibomian gland”, “meibomian gland dysfunction”, “contact lens”, and/or “dry eye”. Of the 115 papers reviewed, 22 articles were identified that examined the association between CL and MGD. Fifteen showed that CL wear affects the morphology and function of meibomian glands (MGs), while seven reported no significant impact of CL wear on MGs. This review provides an overview of these studies, emphasizing the diagnostic tests of MGD and conclusions. The review highlights the need for longitudinal prospective large cohort studies with control non- CL wearers to clarify the ambiguous relationship between MGD and CL wear, with special attention to varying CL material and wear times in order to identify the long-term impact of CLs on MG. (AU)

Topical review of the relationship between contact lens wear and meibomian gland dysfunction.

Contact lens (CL) wearers often suffer from ocular discomfort, which leads to cessation of CL wear. About 30% to 50% of CL wearers complain of dry eye (DE) symptoms. Meibomian gland dysfunction (MGD) is considered the most common cause of evaporative DE. Numerous studies have investigated whether CL wear might affect the meibomian glands. This manuscript reviews studies examining the relationship between CL use and MGD. A PubMed database search was conducted for studies published between 1980-2021 with one or a combination of search terms related to "meibomian gland", "meibomian gland dysfunction", "contact lens", and/or "dry eye". Of the 115 papers reviewed, 22 articles were identified that examined the association between CL and MGD. Fifteen showed that CL wear affects the morphology and function of meibomian glands (MGs), while seven reported no significant impact of CL wear on MGs. This review provides an overview of these studies, emphasizing the diagnostic tests of MGD and conclusions. The review highlights the need for longitudinal prospective large cohort studies with control non- CL wearers to clarify the ambiguous relationship between MGD and CL wear, with special attention to varying CL material and wear times in order to identify the long-term impact of CLs on MG.

Repeatability and reproducibility of Cobra HD fundus camera meibography in young adults with and without symptoms of dry eye.

PURPOSE: The inter-session repeatability (ISR), inter-examiner reproducibility (IER) and within-subject variability (WSV) of the Cobra HD fundus camera meibographer were examined in participants with and without dry eye symptoms. METHODS: Symptoms were determined based on Ocular Surface Disease Index scores (≥13 being considered symptomatic), and subgroups were compared using the Mann-Whitney U-test. Images of meibomian glands (MGs) from the upper and lower right eyelids were captured by two examiners on the same day (S1) to determine IER. One examiner repeated the measurements on a second day (S2) to obtain the ISR. ISR, IER and WSV were calculated using Friedman, correlation tests and Bland and Altman analyses with mean differences (md) and 95% confidence intervals (CIs), within-subject standard deviations (Sw) and intra-class correlation coefficients (ICC). RESULTS: The ISR experiment included 72 participants (mean age: 23 ± 5 years, range: 19-43, 36 symptomatic). Mean MG loss of the upper (S1: 13.5 ± 9.5%, S2: 12.8 ± 8.5%) and lower eyelids (S1: 7.5 ± 6.9%, S2: 7.3 ± 6.3%) was not significantly different between sessions for all participants, symptomatic and asymptomatic subgroups for both eyelids. The ISR Sw for the upper and lower eyelids was 1.3% and 1.0%; md was 0.7 ± 3.5% (CI:-6.25% to 7.62%) and 0.1 ± 2.1% (CI: -3.94% to 4.17%), respectively. The IER experiment included 74 participants (mean age: 23 ± 5 years, range: 19-43, 37 symptomatic). Mean MG loss of the upper (Examiner 1: 12.7 ± 8.2%, Examiner 2: 13.1 ± 8.0%) and lower eyelids (Examiner 1: 7.0 ± 6.2%, Examiner 2: 7.4 ± 6.2%) was not significantly different between examiners for all participants, symptomatic and asymptomatic subgroups for both eyelids. The IER ICC values were >0.86 for all conditions, Sw was 1.3% and 1.2%, with a md of -0.4 ± 3.2% (CI: -6.65% to 5.90%) and -0.4 ± 2.9% (CI: -6.15% to 5.31%), respectively. The WSV Sw values were <1.4%, and ICC values were >0.89 for both eyelids, examiners and experimental sessions. CONCLUSIONS: The Cobra HD fundus camera demonstrates good repeatability, reproducibility and low WSV, and is a reliable clinical instrument for meibography.

Agudeza Visual Dinámica / Acuidade Visual Dinâmica / Dynamic Visual Acuity

Resumen Presentamos una revisión del tema relativo a la habilidad visual para discriminar detalles sutiles sobre objetos en movimiento (AVD: Agudeza Visual Dinámica), mostrando las diferencias más relevantes, que han sido atribuidas a esta capacidad visual en comparación con la AVE (AV estática). Actualmente, es sabido que la correlación entre AVE y AVD es baja. Además, al medir la AVD no solo evaluamos la mínima separación espacial que el sistema visual puede resolver, sino también la funcionalidad del sistema oculomotor. De este modo, valorar la AVD implica medir la capacidad del ojo como buscador activo de información. Hoy sabemos que la AVD es uno de los mejores indicadores de éxito en ciertas especialidades deportivas (tenis de mesa, baseball, etc.) y que correlaciona negativamente con la siniestralidad en accidentes de tráfico. Entre los factores investigados que producen una reducción significativa de la resolución espacial dinámica destacan: (a) la velocidad del estímulo, afectando tanto a trayectorias verticales como horizontales; (b) el tiempo de exposición del estímulo; (c) la iluminación ambiental; (d) la disminución del contraste y e) la edad del sujeto. Por otra parte, se ha verificado que esta capacidad visual es susceptible de mejorar con el entrenamiento.

Resumo Apresentamos uma revisão do tema referente a habilidade visual para discriminar sutís detalhes diante de objetos em movimento (AVD: Acuidade Visual Dinâmica), mostrando as diferenças mais relevantes, que foram atribuídas a esta capacidade visual em comparação com a AVE (AV estática). Atualmente sabemos que a correlação entre AVE e AVD é baixa. Sendo assim, ao medir a AVD não somente avaliamos a mínima separação espacial que o sistema visual pode resolver, também avaliamos a funcionalidade do sistema oculomotor. Desse modo, para avaliar a AVD requer medir a capacidade do olho como buscador ativo de informação. Hoje sabemos que a AVD é um dos melhores indicadores de êxito em certas especialidades desportivas (tênis de mesa, baseball, etc.) e que se correlaciona negativamente com sinistralidade nos acidentes de trânsito. Entre os fatores investigados que produzem una redução significativa da resolução espacial dinâmica destacam: (a) a velocidade do estímulo, que afeta tanto as trajetórias verticais como horizontais; (b) o tempo de exposição do estímulo; (c) a iluminação ambiental; (d) a diminuição do contraste e (e) a idade do sujeito. Por outro lado, verificou-se que esta capacidade visual é suscetível a melhorar com treinamento.

Abstract We present a review on the visual ability to discriminate fine details of moving objects (DVA: Dynamic Visual Acuity), showing the most relevant differences, which have been attributed to this visual capacity in comparison to SVA (static visual acuity). It is known that the correlation between SVA and DVA is low. Moreover, when DVA is measured, not only the minimum spatial separation that the visual system can resolve is evaluated, but also the functionality of the oculomotor system. Therefore, assessing DVA also involves measuring the ability of the eye to actively seek information. Nowadays, it is known that DVA is one of the best indicators of success in certain sports specialties (table tennis, baseball, etc...) and that it negatively correlates with accident rates in traffic scenarios. The investigated factors that produce a significant reduction in dynamic spatial resolution are: (a) the speed of the stimulus, affecting both vertical and horizontal trajectories; (b) the stimulus exposure time; (c) ambient illumination; (d) reduction in contrast and (e) subject age. Moreover, it has been verified that this visual capacity is likely to improve with training.

Changes in Peripheral Refraction, Higher-Order Aberrations, and Accommodative Lag With a Radial Refractive Gradient Contact Lens in Young Myopes.

PURPOSE: To evaluate changes in the peripheral refraction (PR), visual quality, and accommodative lag with a novel soft radial refractive gradient (SRRG) experimental contact lens that produces peripheral myopic defocus. METHODS: 59 myopic right eyes were fitted with the lens. The PR was measured up to 30° in the nasal and temporal horizontal visual fields and compared with values obtained without the lens. The accommodative lag was measured monocularly using the distance-induced condition method at 40 cm, and the higher-order aberrations (HOAs) of the entire eye were obtained for 3- and 5-mm pupils by aberrometry. Visual performance was assessed through contrast sensitivity function (CSF). RESULTS: With the lens, the relative PR became significantly less hyperopic from 30° to 15° temporally and 30° nasally in the M and J0 refractive components (P<0.05). Cylinder foci showed significant myopization from 30° to 15° temporally and 30° to 25° nasally (P<0.05). The HOAs increased significantly, the CSF decreased slightly but reached statistical significance for 6 and 12 cycles per degree (P<0.05), and the accommodative lag decreased significantly with the SRRG lens (P=0.0001). There was a moderate correlation between HOAs and CSF at medium and high spatial frequencies. CONCLUSION: The SRRG lens induced a significant change in PR, particularly in the temporal retina. Tangential and sagittal foci changed significantly in the peripheral nasal and temporal retina. The decreased accommodative lag and increased HOAs particularly in coma-like aberration may positively affect myopia control. A longitudinal study is needed to confirm this potential.

Myopia Control with a Novel Peripheral Gradient Soft Lens and Orthokeratology: A 2-Year Clinical Trial.

OBJECTIVE: To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) contact lenses, orthokeratology (OK), and single vision (SV) spectacle lenses (control) during a period of 1 year before treatment and 2 years after treatment. METHODS: This was a prospective, longitudinal, nonrandomized study. The study groups consisted of 30, 29, and 41 children, respectively. The axial length (AL) was measured during 2 years after recruitment and lens fitting. RESULTS: The baseline refractive sphere was correlated significantly (Spearman's Rho (ρ) correlation = 0.542; P < 0.0001) with the amount of myopia progression before baseline. After 2 years, the mean myopia progression values for the SRRG, OK, and SV groups were -0.56 ± 0.51, -0.32 ± 0.53, and -0.98 ± 0.58 diopter, respectively. The results represent reductions in myopic progression of 43% and 67% for the SRRG and OK groups, respectively, compared to the SV group. The AL increased 27% and 38% less in the SRRG and OK groups, respectively compared with the SV group at the 2-year visit (P < 0.05). Axial elongation was not significantly different between SRRG and OK (P = 0.430). CONCLUSION: The SRRG lens significantly decreased AL elongation compared to the SV control group. The SRRG lens was similarly effective to OK in preventing myopia progression in myopic children and adolescent.

Efficacy of a gas permeable contact lens to induce peripheral myopic defocus.

PURPOSE: The purpose of this work was to evaluate the potential of a novel custom-designed rigid gas permeable (RGP) contact lens to modify the relative peripheral refractive error in a sample of myopic patients. METHODS: Fifty-two right eyes of 52 myopic patients (mean [±SD] age, 21 [±2] years) with spherical refractive errors ranging from -0.75 to -8.00 diopters (D) and refractive astigmatism of 1.00 D or less were fitted with a novel experimental RGP (ExpRGP) lens designed to create myopic defocus in the peripheral retina. A standard RGP (StdRGP) lens was used as a control in the same eye. The relative peripheral refractive error was measured without the lens and with each of two lenses (StdRGP and ExpRGP) using an open-field autorefractometer from 30 degrees nasal to 30 degrees temporal, in 5-degree steps. The effectiveness of the lens design was evaluated as the amount of relative peripheral refractive error difference induced by the ExpRGP compared with no lens and with StdRGP conditions at 30 degrees in the nasal and temporal (averaged) peripheral visual fields. RESULTS: Experimental RGP lens induced a significant change in relative peripheral refractive error compared with the no-lens condition (baseline), beyond the 10 degrees of eccentricity to the nasal and temporal side of the visual field (p < 0.05). The maximum effect was achieved at 30 degrees. Wearing the ExpRGP lens, 60% of the eyes had peripheral myopia exceeding -1.00 D, whereas none of the eyes presented with this feature at baseline. There was no significant correlation (r = 0.04; p = 0.756) between the degree of myopia induced at 30 degrees of eccentricity of the visual field with the ExpRGP lens and the baseline refractive error. CONCLUSIONS: Custom-designed RGP contact lenses can generate a significant degree of relative peripheral myopia in myopic patients regardless of their baseline spherical equivalent refractive error.

Tear break-up time for tear film evaluation: Are moistening solutions interchangeable?

PURPOSE: It was the main purpose of this study to investigate the influence of the moistening solution on TBUT measurements in an asymptomatic population. METHODS: An online survey was employed to determine the compliance of Spanish eye care practitioners with the recommended normalized procedure to administer TBUT. For the purpose of examining the clinical relevance of discrepancies from the recommended procedure, a randomized, double-masked, bilateral study was designed in which a micropipette was used to moisten fluorescein strips with a controlled volume of six different solutions, commonly available in the contact lens office, and TBUT was measured in 58 non-dry eye (OSDI<15) subjects (age from 19 to 32 years). RESULTS: Results from the online survey revealed that 64% of Spanish practitioners frequently use (or have used) different solutions to moisten fluorescein strips during TBUT assessment. Statistically significant differences in TBUT values were found between the various solutions as a whole (χ(2)=198.384, p<0.001), as well as between all solutions when explored pair-wise (all p<0.001), except for the two saline solutions. CONCLUSIONS: The present findings support the relevance of selecting the appropriate solution when conducting TBUT for the evaluation of the tear film. Deviations from the recommended procedure may result in misdiagnosis of dry eye and unnecessary patient referral.

Effects of transient blur and VDT screen luminance changes on eyeblink rate.

PURPOSE: A study was designed to evaluate the efficacy of three different strategies aiming at increasing spontaneous eyeblink rate (SEBR) during computer use. METHODS: A total of 12 subjects (5 female) with a mean age of 28.7 years were instructed to read a text presented on a computer display terminal during 15min. Four reading sessions (reference and three "blinking events" [BE]) were programmed in which SEBR was digitally recorded. "Blinking events" were based on either a slight distortion of the text characters or on the presentation of a white screen instead of the text, with or without accompanying blinking instructions. All BE had a duration of 20ms and occurred every 15s. Participants graded the intrusiveness of each BE configuration, and the number of lines participants read in each session was recorded. RESULTS: Data from 11 subjects was analysed. A statistically significant difference in SEBR was encountered between the experimental configuration consisting on a white screen plus blinking instructions (7.8 blinks/min) and both reference (5.2 blinks/min; p=0.049) and white screen without blinking instructions (4.8 blinks/min; p=0.038). All three BE had superior levels of intrusiveness than reference conditions, although the performance of participants (line count) was not compromised. CONCLUSIONS: The joint contribution of white screen and blinking instructions has been shown to result in a short term improvement in blinking rate in the present sample of non-dry eye computer users. Further work is necessary to improve the acceptance of any BE aiming at influencing SEBR.

Toric double tear reservoir contact lens in orthokeratology for astigmatism.

OBJECTIVES: This study aimed at assessing the performance of a double tear reservoir toric reverse geometry contact lens design for the correction of myopic and astigmatic refractive errors through overnight orthokeratology (Ortho-K). METHODS: Consecutive records of a total of 32 patients with refractive astigmatism greater than 1.25 D at any orientation, best corrected distance monocular visual acuity ≥ 1.00 (decimal) before Ortho-K treatment and stable ocular refraction for at least 1 month at the time of the last visit were retrospectively examined. Preorthokeratology and postorthokeratology information included noncycloplegic subjective refraction, best-corrected visual acuity, pupil diameter, corneal topography, and ocular aberrometry. The associations between the achieved myopic and cylinder reduction and the modifications in various corneal topographic parameters were investigated. Right eyes were chosen for data analysis. RESULTS: A statistically significant difference (Z=-4.805; P<0.001) was encountered between initial refractive sphere and final residual refractive sphere, with a dioptric change of -2.05 ± 1.46 D (median: -1.88; -5.25 to 0.50), accounting for a change of 106% of the initial myopia. Similarly, differences between pretreatment and posttreatment refractive cylinders were significant (Z=-4.945; P<0.001), with a dioptric change of -1.80 ± 1.06 D (median: -1.50; -5.25 to -0.50), that is, a change of 85% of the initial astigmatism. Changes in topographic Best Fit Sphere and Best Fit Toric presented a strong positive correlation with the accomplished myopic and astigmatic refractive changes, respectively. CONCLUSIONS: The results of this investigation suggest that the correction of astigmatic errors with toric orthokeratology lens designs may have a promising future.

Knowledge and use of tear film evaluation tests by spanish practitioners.

PURPOSE: The present study aimed at investigating the use and knowledge of tear film and dry eye evaluation tests by a representative sample of Spanish optometrists and ophthalmologists. METHODS: A simple on-line survey was designed to explore the preferred tests for tear film evaluation and dry eye diagnosis. Additional questions surveyed knowledge of basic tear film evaluation concepts, attitude (proactive or reactive) toward patient symptoms and use of standardized dry eye questionnaires. Respondents also provided information regarding academic background, continuing education and training courses, and weekly number of tear film examinations. RESULTS: A total of 140 optometrists and 103 ophthalmologists responded to the survey. The tear break-up time test was the first preference of optometrists and ophthalmologists, whereas the Schirmer test and the non-invasive break-up time were frequently reported by ophthalmologists and optometrists, respectively, to supplement a first test. Optometrists and ophthalmologists were similar in terms of continuing education, knowledge of basic tear film concepts, and attitude regarding symptoms. Continuing education was found to positively influence knowledge, attitude toward symptoms and use of more sophisticated tear film evaluation tests. Standardized dry eye questionnaires were rarely used. A strong positive statistically significant correlation was encountered between the number of continuing education and training courses and the number of weekly tear film examinations. CONCLUSIONS: Continuing education is an invaluable tool for practitioners to increase their self-confidence and improve their clinical practice when conducting tear film evaluations and dry eye diagnosis.

Temporal stability in the perception of dry eye ocular discomfort symptoms.

PURPOSE: A prospective longitudinal study was designed to investigate the ability of patients with tear deficiency to correctly recall their past symptoms. The ultimate goal of the study was to contribute to the ongoing research concerning the lack of association between dry eye symptomatology and clinical tests of tear film evaluation. METHODS: A total of 26 subjects with ages ranging from 29 to 61 years participated in the study. All subjects reported symptoms associated with tear deficiency, although none had been diagnosed with dry eye disease. Subjects were instructed to grade their symptoms on two different occasions, at the precise moment they were experiencing them, by means of a home questionnaire, and through a recall questionnaire, which was administered within a maximum interval of 10 days from the first questionnaire. Tear evaluation tests were performed at this second time. Non-parametric statistical analyses were used to investigate the relationship between present and recalled symptoms and between symptoms and signs, as well as between the different dry eye tests. The contributions of age, gender, and recall period were also evaluated. RESULTS: With the exception of irritation (p = 0.029) and scratchiness (p = 0.025), no statistically significant difference was encountered between home and recall questionnaires, although females were found to recall their symptoms slightly better than males (p = 0.048). An increase in the severity of the symptoms was associated with a better recollection (p = 0.007). Symptoms (home or recalled) and clinical signs were not correlated, although the recalled symptom of scratchiness presented moderately strong correlations with several dry eye tests. CONCLUSIONS: Although the lack of correlation between dry eye tests and symptoms mirrored previous research, symptoms recall was found to follow certain interesting patterns, similar to those published in pain research literature.

Una tarea para evaluar la agudeza visual dinámica y una valoración de la estabilidad de sus mediciones / No disponible

Apenas existen instrumentos de medición adecuados de la capacidad paradiscriminar estímulos en movimiento, cuya aplicación resulte fácil y cuyasvaloraciones sean estables a través del tiempo. También se constata laausencia de un paradigma de evaluación que se muestre sensible anteaquellos factores que, en estudios previos, han sido relacionados con lavisión dinámica. En consecuencia, nos proponemos como objetivo diseñaruna tarea que permita la valoración de la agudeza visual dinámica (AVD),definida como la capacidad de discriminar detalles en condiciones demovimiento relativo entre sujeto y objeto. Para ello, hemos realizado dosestudios psicofísicos. El primero muestra que la AVD resulta modulada portres factores: velocidad, contraste y trayectoria del estímulo móvil,interaccionando significativamente los dos primeros. En el segundo estudio,hemos averiguado la correlación entre la AVD obtenida por los sujetos entres momentos separados, al menos, una semana (t1 y t2) y entre, al menos,dos semanas (t2 y t3). Estas oscilaron entre 0,78-0,92, para una velocidad de14,1º/seg. y entre 0,72-0,85 para una velocidad de 1,4º/seg. Finalmente,comparamos las valoraciones de AVD en esos tres momentos, noencontrando diferencias significativas en el factor temporal. Concluimosque, nuestra tarea constituye una herramienta objetiva, y de fácil aplicacióntanto clínica como experimental, muy útil para valorar la AVD(AU)

The effects of drift and displacement motion on Dynamic Visual Acuity

Dynamic Visual Acuity (DVA) can be measured from two types ofequivalently considered movement referred to as drifting-motion anddisplacement-motion. Displacement motion can be best described as thehorizontal displacement of a stimulus, thus implying pursuit eyemovements, and involves moving the stimulus from the fixation point ofgaze towards the periphery. The drifting motion of a Gabor patch, forexample, avoids pursuit eye movements, since the gaze is fixed in a point ofthe patch. Our data shows that in both types of movement visual acuity(VA), expressed in terms of spatial frequency, diminished as the velocity ofthe target increased. However, the slope of the regression equation indicatedthat this impairment is more than two-fold in the case of drifting-motionwhen compared to displacement motion. As the greater impairment tookplace when pursuit eye movements did not exist, our data suggests that thesetwo types of motions correct differently for retinal slip. Retinal slip appearsto be less efficiently compensated for in the case of drifting motion havingadverse consequences on VA, while retinal slip has a higher tolerance in thecase of displacement motion exhibited by the performance in VA

Experimental study of visual training effects in shooting initiation.

INTRODUCTION: The present study was conducted to investigate the influence of specific visual training in shooting initiation performance. METHODS: Seventy-one first-year university students were divided randomly into two groups. The experimental group followed a nine-session shooting training program that included technical, physical and psychological components, along with specific visual exercises. The control group followed the same program with one difference: this group received theoretical lectures on psychological training techniques instead of doing visual exercises. Pre- and post-test results were obtained for shooting, concentration, saccades and visual acuity. RESULTS: Statistical analysis indicated significant gains in the four mentioned variables for the experimental group. The control group also showed significant differences in the three first variables but no significant improvement in visual acuity. No significant differences in shooting performance were observed between groups. CONCLUSIONS: The effect of vision training on sports initiation performance is still not clear. It cannot be assumed that the improvement is transferable to the performance of precision shooting at the stage of sports initiation.