Characterization, passive and active treatment in strabismic amblyopia: a narrative review

Strabismic amblyopia is characterized by a distorted spatial perception. In this condition, the neurofunctional disorder occurring during first years of life provoke several monocular and binocular anomalies such as crowding, deficits in the accommodative response, contrast sensitivity, and ocular motility abilities. The inhibition of the binocular function of the brain by the misaligned amblyopic eye induces a binocular imbalance leading to interocular suppression and the reduction or lack of stereoacuity. Passive treatments such as occlusion, optical and/or pharmacological penalization, and Bangerter foils has been demonstrated to be potentially useful treatments for strabismic amblyopia. Recent researches have proved new pharmacological options to improve and maintain visual acuity after occlusion treatment in strabismic amblyopia. Likewise, the active vision therapy, in the last years, is becoming a very relevant therapeutic option in combination with passive treatments, especially during and after monocular therapy, in the attempt of recovering the imbalanced binocular vision.Supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal (RYC-2016-20471)

Stereoacuity Improvement using Random-Dot Video Games

Conventional amblyopia therapy involves occlusion or penalization of the dominant eye, though these methods enhance stereoscopic visual acuity in fewer than 30% of cases. To improve these results, we propose a treatment in the form of a video game, using random-dot stimuli and perceptual learning techniques to stimulate stereoacuity. The protocol is defined for stereo-deficient patients between 7-14 years of age who have already received treatment for amblyopia and have a monocular best corrected distance visual acuity of at least 0.1 logMAR. Patients are required to complete a perceptual learning program at home using the video game. While compliance is stored automatically in the cloud, periodic optometry center visits are used to track patient evolution and adjust the game's stereoscopic demand until the smallest detectable disparity is achieved. The protocol has proved to be successful, and effectiveness is gauged in terms of a two-level gain on a random stereoacuity test (global stereoacuity or cyclopean stereoacuity reference test). Moreover, the random-dot stimuli learning transfers to medial lateral stereoscopic acuity according to a Wirt Circles test, in which success criteria is a final stereoacuity of over 140", and the attained enhancement corresponds to no less than two levels of stereoscopic acuity. Six months later, a random-dot stereoacuity test recorded no reduction in the stereoacuity that was achieved

Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review

Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process. Visual deficits in amblyopia and their neural mechanisms associated are revised, including visual acuity loss, contrast sensitivity reduction and stereopsis impairment. Likewise, the most appropriate stimuli according to the literature that should be used for an efficient rehabilitation of the amblyopic eye are described in detail, including optotypes, Gabor’s patches, random-dot stimuli and Vernier’s stimuli. Finally, the properties of these stimuli that can be modified during the visual training are discussed, as well as the psychophysical method of their presentation and the type of environment used (perceptual learning, dichoptic stimulation or virtual reality). Vision therapy using all these revised concepts can be an effective option for treating amblyopia or accelerating the treatment period when combining with patching. It is essential to adapt the stimuli to the patient’s individual features in both monocular and binocular training.The authors C.J.H.-R., D.P.P., A.M.-M., D.d.F., L.L.-V., M.B.C.-M. have been funded by CDTI (Centro para el Desarrollo Tecnológico Industrial, Ministry of Economy and Competitiveness of Spain) and FEDER (Fondos Europeos de Desarrollo Regional) funds by means of the program PID (“Proyectos de Investigación y Desarrollo”) in the context of the Project NEIVATECH (“Neuroplasticity through virtual reality for amblyopia”, application number 111705). The author León Morales-Quezada is supported by funding from the Spaulding Research Catalyst award. The author David P Piñero has been also supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471

Efficacy of Perceptual Learning-Based Vision Training as an Adjuvant to Occlusion Therapy in the Management of Amblyopia: A Pilot Study

A retrospective study was conducted to evaluate preliminarily the efficacy of perceptual learning (PL) visual training in medium-term follow-up with a specific software (Amblyopia iNET, Home Therapy Systems Inc., Gold Canyon, AZ, USA) for visual acuity (VA) and contrast sensitivity (CS) recovering in a sample of 14 moderate to severe amblyopic subjects with a previously unsuccessful outcome or failure with patching (PL Group). This efficacy was compared with that achieved in a patching control group (13 subjects, Patching 2). At one-month follow-up, a significant VA improvement in the amblyopic eye (AE) was observed in both groups, with no significant differences between them. Additionally, CS was measured in PL Group and exhibited a significant improvement in the AE one month after the beginning of treatment for 3, 6, 12, and 18 cycles/º (p = 0.003). Both groups showed long-lasting retention of visual improvements. A combined therapy of PL-based visual training and patching seems to be effective for improving VA in children with amblyopia who did not recover vision with patching alone or had a poor patching compliance. This preliminary outcome should be confirmed in future clinical trials.The author David P Piñero has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471

Actualización en ambliopía

L'ambliopia és una condició produït per un desenvolupament visual anòmal que provoca una pèrdua de l'agudesa visual i d'altres habilitats visuals binoculars. Apareix principalment en les primeres etapes de la vida i ocasiona problemes en la qualitat de vida del pacient si no es detecta a temps. L'objectiu d'aquest treball és proporcionar una actualització dels últims avenços en el tractament de l'ambliopia mitjançant la recerca bibliogràfica de documents i articles, la majoria extretes de les bases de dades Medline i PubMed. El tractament tradicional per l'ambliopia és l'oclusió de l'ull dominant mitjançant un pegat per entrenar l'ull ambliop. En els estudis més recents s'han suggerit tractaments d'aprenentatge perceptiu mitjançant videojocs i sistemes de realitat virtual per a obtenir millors resultats i millorar les habilitats visuals com la estereopsis i la sensibilitat al contrast. Però no poden considerar-se substituts dels tractaments convencionals perquè encara estan en fase d'investigació.La ambliopía es una condición producida por un desarrollo visual anómalo que provoca una pérdida de la agudeza visual y de otras habilidades visuales binoculares. Aparece principalmente en las primeras etapas de la vida y ocasiona problemas en la calidad de vida del paciente si no se detecta a tiempo. El objetivo de este trabajo es proporcionar una actualización de los últimos avances en el tratamiento de la ambliopía mediante la búsqueda bibliográfica de documentos y artículos, la mayoría extraídas de las bases de datos Medline y PubMed. El tratamiento tradicional para la ambliopía es la oclusión del ojo dominante mediante un parche para entrenar el ojo amblíope. En los estudios más recientes se han sugerido tratamientos de aprendizaje perceptivo mediante videojuegos y sistemas de realidad virtual para obtener mejores resultados y mejorar las habilidades visuales como la estereopsis y la sensibilidad al contraste. Pero no pueden considerarse sustitutos de los tratamientos convencionales porque todavía están en fase de investigación.Amblyopia is a condition produced by an abnormal visual development that causes a loss of visual acuity and other binocular visual skills. It appears mainly in the early stages of life and causes problems in the patient's quality of life if not detected early. The aim of this thesis is to provide an update on the latest advances in the treatment of amblyopia by means of a literature search of papers and articles, mostly extracted from Medline and PubMed databases. The traditional treatment for amblyopia is occlusion of the dominant eye by patching to train the amblyopic eye. More recent studies have suggested perceptual learning treatments using video games and virtual reality systems to obtain better results and improve visual skills such as stereopsis and contrast sensitivity. But they cannot be considered substitutes for conventional treatments because they are still in the research phase

Effect of vision-based treatments on visual acuity and motor function in children with amblyopia

Purpose: To investigate existing as well as novel vision-based treatments in children with amblyopia and determine the utility of motor function as a potential outcome measure. Methods: Three experiments were conducted. Experiment 1 was a meta-analysis that initially found 3346 articles through a comprehensive literature search in Ovid Embase, PubMed, the Cochrane Library, Vision Cite, and Scopus. The search was for randomized clinical trials (RCTs) from 1975 to June 2020 and investigated improvement in visual acuity (VA) of the amblyopic eye. The population was patients aged 4 – 17 years old with amblyopia undergoing vision-based treatment. Two independent reviewers narrowed the results to 36 articles. Meta-analyses and a meta-regression were conducted on a subset of these RCTs in order to determine if any one vision-based treatment was superior at improving VA of the amblyopic eye. The goal of Experiment 2 was to characterize the types of motor function deficits seen in children (aged 3 - >7) with amblyopia and binocular vision problems (anisometropia without amblyopia, and strabismus without amblyopia), compared to controls. A total of 64 participants were recruited. Visual acuity (HOTV), stereopsis (Randot Preschool Stereoacuity Test), suppression (Worth 4 dot test) and motor function scores were assessed (Movement Assessment Battery for Children 2nd edition). Experiment 3 involved developing a binocular video treatment for use in a multi-site RCT. This treatment aimed for children aged 3 – 6 with amblyopia was created by transforming an existing cartoon (Q Pootle 5, provided by the British Broadcasting Corporation) into a dichoptic format. The goal was to create a video treatment that inspired high adherence rates and could separate specific, key characters between the eyes. Results: In Experiment 1, of the 3346 studies identified, 36 were included in a narrative synthesis. A random effects meta-analysis (five studies) compared the efficacy of binocular treatments versus patching: mean difference −0.03 logMAR; 95% CI 0.01 to 0.04 (p<0.001), favouring patching. An exploratory study-level regression (18 studies) showed no statistically significant differences between vision-based treatments and a reference group of 2–5 hours of patching. Age, sample size and pre- randomisation optical treatment were not statistically significantly associated with changes in amblyopic eye acuity. A network meta-analysis (26 studies) comparing vision-based treatments to patching 2–5 hours found one statistically significant comparison, namely, the favouring of a combination of two treatment arms comparing combination and binocular treatments, against patching 2–5 hours: standard mean difference: 2.63; 95% CI 1.18 to 4.09. However, this result was an indirect comparison calculated from a single study. A linear regression analysis (17 studies) found a significant relationship between adherence and effect size, but the model did not completely fit the data: regression coefficient 0.022; 95% CI 0.004 to 0.040 (p=0.02). In Experiment 2, An ANCOVA did not find a significant main effect of patient group on total motor function standard scores F(2, 51) = 1.59, p = 0.82). None of the covariates (visual acuity and stereopsis) were significantly associated with total motor function scores (lowest p = 0.42). When investigating the sub-categories of the MABC-2, one-way ANOVAs showed no significant effect of group for manual dexterity, catching and throwing, and balance scores. A novel binocular treatment was developed from the ground up for Experiment 3. The resulting treatment separated key characters and/or items between the eyes, to ensure that the use of the amblyopic eye was essential for the patient to understand each scene. The cartoon was successfully ported to the New Nintendo 3DS XL, a handheld device that allows dichoptic videos to be shown without the need for glasses. This treatment is distinct from previous video treatments in the literature and we hypothesize that it will improve visual acuity of the amblyopic eye, stereopsis and fine and gross motor function skills in children with amblyopia. Conclusion: Clinicians have many available options for treatment that are just as efficacious as patching for 2-5 hours. This includes the possibility of binocular treatments, which may also improve stereopsis. More research on symptoms other than just visual acuity, such as motor function, should be further investigated in patients with amblyopia in order to provide a complete healthcare plan

Global research of artificial intelligence in strabismus: a bibliometric analysis

PurposeTo analyze the global publications on artificial intelligence (AI) in strabismus using a bibliometric approach.MethodsThe Web of Science Core Collection (WoSCC) database was used to retrieve all of the publications on AI in strabismus from 2002 to 2023. We analyzed the publication and citation trend and identified highly-cited articles, prolific countries, institutions, authors and journals, relevant research domains and keywords. VOSviewer (software) and Bibliometrix (package) were used for data analysis and visualization.ResultsBy analyzing a total of 146 relevant publications, this study found an overall increasing trend in the number of annual publications and citations in the last decade. USA was the most productive country with the closest international cooperation. The top 3 research domains were Ophthalmology, Engineering Biomedical and Optics. Journal of AAPOS was the most productive journal in this field. The keywords analysis showed that “deep learning” and “machine learning” may be the hotspots in the future.ConclusionIn recent years, research on the application of AI in strabismus has made remarkable progress. The future trends will be toward optimized technology and algorithms. Our findings help researchers better understand the development of this field and provide valuable clues for future research directions

A Covered Eye Fails To Follow an Object Moving in Depth

To clearly view approaching objects, the eyes rotate inward (vergence), and the intraocular lenses focus (accommodation). Current ocular control models assume both eyes are driven by unitary vergence and unitary accommodation commands that causally interact. The models typically describe discrete gaze shifts to non-accommodative targets performed under laboratory conditions. We probe these unitary signals using a physical stimulus moving in depth on the midline while recording vergence and accommodation simultaneously from both eyes in normal observers. Using monocular viewing, retinal disparity is removed, leaving only monocular cues for interpreting the object\u27s motion in depth. The viewing eye always followed the target\u27s motion. However, the occluded eye did not follow the target, and surprisingly, rotated out of phase with it. In contrast, accommodation in both eyes was synchronized with the target under monocular viewing. The results challenge existing unitary vergence command theories, and causal accommodation-vergence linkage

Eye tracking in optometry: A systematic review

This systematic review examines the use of eye-tracking devices in optometry, describing their main characteristics, areas of application and metrics used. Using the PRISMA method, a systematic search was performed of three databases. The search strategy identified 141 reports relevant to this topic, indicating the exponential growth over the past ten years of the use of eye trackers in optometry. Eye-tracking technology was applied in at least 12 areas of the field of optometry and rehabilitation, the main ones being optometric device technology, and the assessment, treatment, and analysis of ocular disorders. The main devices reported on were infrared light-based and had an image capture frequency of 60 Hz to 2000 Hz. The main metrics mentioned were fixations, saccadic movements, smooth pursuit, microsaccades, and pupil variables. Study quality was sometimes limited in that incomplete information was provided regarding the devices used, the study design, the methods used, participants' visual function and statistical treatment of data. While there is still a need for more research in this area, eye-tracking devices should be more actively incorporated as a useful tool with both clinical and research applications. This review highlights the robustness this technology offers to obtain objective information about a person's vision in terms of optometry and visual function, with implications for improving visual health services and our understanding of the vision process