Esotropia and Exotropia Preferred Practice Pattern®

Enhancing automated strabismus classification with limited data: Data augmentation using StyleGAN2-ADA

In this study, we propose a generative data augmentation technique to overcome the challenges of severely limited data when designing a deep learning-based automated strabismus diagnosis system. We implement a generative model based on the StyleGAN2-ADA model for system design and assess strabismus classification performance using two classifiers. We evaluate the capability of our proposed method against traditional data augmentation techniques and confirm a substantial enhancement in performance. Furthermore, we conduct experiments to explore the relationship between the diagnosis agreement among ophthalmologists and the generation performance of the generative model. Beyond FID, we validate the generative samples on the classifier to establish their practicality. Through these experiments, we demonstrate that the generative model-based data augmentation improves overall quantitative performance in scenarios of extreme data scarcity and effectively mitigates overfitting issues during deep learning model training.

Refractive Profile of Surgical Patients with Intermittent Exotropia: A Large-Sample Cross-Sectional Study in Southern China

PURPOSE

To describe the refractive profile of surgical patients with intermittent exotropia (IXT) residing in southern China.

METHODS

Medical records of patients who received strabismus surgery between June 2014 and August 2020 were retrospectively reviewed. Clinical data, including age, sex, refractive errors, preoperative angle of deviation, types of exotropia, accommodative convergence to accommodation ratio (AC/A ratio) and stereopsis, were investigated.

RESULTS

A total of 2250 patients were included, and 93.6% of patients were younger than 30 years of age. The mean angle of exodeviation was 37.0 ± 14.7 prism degree (PD) and 37.5 ± 15.8 PD at distance and near, respectively. Mean spherical equivalent refraction (SER) values were -0.7 ± 2.4 D and -0.8 ± 2.5 D in the dominant eye and nondominant eye, respectively. Significant differences in SER were observed between the dominant eye and nondominant eye among children at 6 years old or younger. The percentage of myopia increased from 11.0% in children (≤6 years old) to 77.9% in teenagers (13-18 years of age). Significant positive associations between the magnitude of exodeviation and the magnitude of myopia were observed (p < 0.0001). Patients with convergence insufficiency type IXT (p < 0.0001) or AC/A < 2 (p < 0.05) showed a greater magnitude of myopia. The mild hyperopia group included a larger proportion of subjects showing a certain degree of stereopsis (p < 0.05).

CONCLUSIONS

Myopia was present in more than half of our patients (51.2%), which is much higher than the percentage in the general population of southern China. Patients with convergence insufficiency, an AC/A ratio < 2, or a larger angle of deviation tended to have a greater magnitude of myopia.

Evaluation of Publications from the American Academy of Ophthalmology: A 5-Year Analysis of Ophthalmology Literature

Objective

To analyze recent publications in Ophthalmology, the journal of the American Academy of Ophthalmology.

Design

Retrospective review of published articles.

Participants

No human participants were involved in the study.

Methods

Articles published in Ophthalmology from January 2018 to December 2022 were reviewed and analyzed.

Main Outcome Measures

Research and review articles were included and analyzed per the following: total number of published articles based on related subspecialty area, level of evidence using the modified Oxford level of evidence, number of citations, number of listed authors, gender of the corresponding author, country of affiliation of the corresponding and contributing author(s), and involvement of consortium(s), group(s), or committee(s).

Results

A total of 965 articles were included. The mean (standard deviation) number of authors per article was 8.6 (5.7) and the majority of corresponding authors were male (665, 70.7%). The greatest number of published articles were related to retina (296, 30.7%) followed by glaucoma (172, 17.8%). The greatest number of Preferred Practice Pattern guidelines were also related to retina (7/24, 29.1%), followed by cornea/dry eye syndrome/external disease (6/24, 25%). Retina (77) had the most level 1 evidence, glaucoma (30) for level 2 evidence, and retina for levels 3 (69) and 4 (65). There were 223 articles contributed by consortia/groups/committees, with most from retina (73, 32.7%) followed by glaucoma (40, 17.9%). The mean number of citations per subspecialty article was highest in retina (45.8/article), followed by uveitis (31.7/article). The United States had the greatest number of affiliated corresponding authors (544, 56.4%), followed by the United Kingdom (68, 7.0%). There were 357 (37.0%) articles with coauthors affiliated outside the corresponding author's country of affiliation, although with a downward trend over the most recent 5-year period. There has been an increasing trend in the number of authors and consortia/group/committee involvement in publications.

Conclusions

Although team science and collaborations have increased recently, ongoing efforts to diversify individuals, groups, and subspecialties may be needed.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Cortical Reorganization After Optical Alignment in Strabismic Patients Outside of Critical Period

PURPOSE

To measure visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortex organization, in older children and adults with horizontal concomitant strabismus before and after strabismus surgery.

METHODS

Using real-time eye tracking to ensure gaze-contingent display, we examined the peripheral visual crowding effects in older children and adults with horizontal concomitant strabismus but without amblyopia before and after strabismus surgery. Patients were asked to discriminate the orientation of the central tumbling E target letter with flankers arranged along the radial or tangential axis in the nasal or temporal hemifield at different eccentricities (5° or 10°). The critical spacing value, which is the minimum space between the target and the flankers required for correct discrimination, was obtained for comparisons before and after strabismus surgery.

RESULTS

Twelve individuals with exotropia (6 males, 21.75 ± 7.29 years, mean ± SD) and 15 individuals with esotropia (6 males, 24.13 ± 5.96 years) participated in this study. We found that strabismic individuals showed significantly larger critical spacing with nasotemporal asymmetry along the radial axis that related to the strabismus pattern, with exotropes exhibiting stronger temporal field crowding and esotropes exhibiting stronger nasal field crowding before surgical alignment. After surgery, the critical spacing was reduced and rebalanced between the nasal and temporal hemifields. Furthermore, the postoperative recovery of stereopsis was associated with the extent of nasotemporal balance of critical spacing.

CONCLUSIONS

We find that optical realignment (i.e., strabismus surgery) can normalize the enlarged visual crowding effects, a reliable psychophysical index of cortical organization, in the peripheral visual field of older children and adults with strabismus and rebalance the nasotemporal asymmetry of crowding, promoting the recovery of postoperative stereopsis. Our results indicated a potential of experience-dependent cortical organization after axial alignment even for individuals who are out of the critical period of visual development, illuminating the capacity and limitations of optics on sensory plasticity and emphasizing the importance of ocular correction for clinical practice.

Harnessing brain plasticity to improve binocular vision in amblyopia: An evidence-based update

Amblyopia is a developmental visual disorder resulting from atypical binocular experience in early childhood that leads to abnormal visual cortex development and vision impairment. Recovery from amblyopia requires significant visual cortex neuroplasticity, i.e. the ability of the central nervous system and its synaptic connections to adapt their structure and function. There is a high level of neuroplasticity in early development and, historically, neuroplastic responses to changes in visual experience were thought to be restricted to a "critical period" in early life. However, as our review now shows, the evidence is growing that plasticity of the adult visual system can also be harnessed to improve vision in amblyopia. Amblyopia treatment involves correcting refractive error to ensure clear and equal retinal image formation in both eyes, then, if necessary, promoting the use of the amblyopic eye by hindering or reducing visual input from the better eye through patching or pharmacologic therapy. Early treatment in children can lead to visual acuity gains and the development of binocular vision in some cases; however, many children do not respond to treatment, and many adults with amblyopia have historically been untreated or undertreated. Here we review the current evidence on how dichoptic training can be used as a novel binocular therapeutic approach to facilitate visual processing of input from the amblyopic eye and can simultaneously engage both eyes in a training task that requires binocular integration. It is a novel and promising treatment for amblyopia in both children and adults.

The Incidence and Risk Factors for Dry Eye After Pediatric Strabismus Surgery

INTRODUCTION

This study aimed to investigate the incidence and risk factors for dry eye after pediatric strabismus surgery.

METHODS

Children aged 5-12 years who underwent strabismus surgery were included in this single-center, prospective, cohort study. The ocular surface assessments were conducted 1 day before and 1, 4, and 8 weeks after surgery. The main outcome measures were the incidence of dry eye after strabismus surgery and associated risk factors.

RESULTS

A total of 84 eyes (48 children) that underwent strabismus surgery were included in the study. The mean age at surgery was 7.21 years. The incidence of dry eye was 47.62% at 1 week, 10.71% at 4 weeks, 0% at 8 weeks after surgery. The preoperative tear breakup time (BUT) was lower in the dry eye group than that in the non-dry eye group (P ≤ 0.01). The univariate analysis showed that preoperative BUT was significantly associated with the incidence of dry eye after pediatric strabismus surgery (odds ratio [OR] 0.647, confidence interval [CI] 0.503-0.833, P ≤ 0.01).

CONCLUSIONS

Dry eye commonly occurs after pediatric strabismus surgery. Tear film instability is more common than deficient aqueous tear production in patients with dry eye after surgery. Children with a low preoperative BUT are more likely to develop dry eye after strabismus surgery.

Visual Crowding Reveals Field- and Axis-Specific Cortical Miswiring After Long-Term Axial Misalignment in Strabismic Patients Without Amblyopia

Purpose

Inspired by physiological and neuroimaging findings that revealed squint-induced modification of cortical volume and visual receptive field in early visual areas, we hypothesized that strabismic eyes without amblyopia manifest an increase in critical spacing of visual crowding, an essential bottleneck on object recognition and reliable psychophysical index of cortical organization.

Methods

We used real-time eye tracking to ensure gaze-contingent display and examined visual crowding in patients with horizontal concomitant strabismus (both esotropia and exotropia) but without amblyopia and age-matched normal controls.

Results

Nineteen patients with exotropia (12 men, mean ± SD = 22.89 ± 7.82 years), 21 patients with esotropia (10 men, mean ± SD = 23.48 ± 6.95 years), and 14 age-matched normal controls (7 men, mean ± SD = 23.07 ± 1.07 years) participated in this study. We found that patients with strabismus without amblyopia showed significantly larger critical spacing with nasotemporal asymmetry in only the radial axis that related to the strabismus pattern, with exotropia exhibiting stronger temporal hemifield crowding and esotropia exhibiting stronger nasal hemifield crowding, in both the deviated and fixating eyes. Moreover, the magnitude of crowding change was related to the duration and degree of strabismic deviation.

Conclusions

Using visual crowding as a psychophysical index of cortical organization, our study demonstrated significantly greater peripheral visual crowding with nasotemporal asymmetry in only the radial axis in patients with strabismus without amblyopia, indicating the existence of hemifield- and axis-specific miswiring of cortical processing in object recognition induced by long-term adaptation to ocular misalignment.

Augmented-Dose Unilateral Recession-Resection Procedure in Acute Acquired Comitant Esotropia

PURPOSE

To compare the surgical amount of unilateral medial rectus recession and lateral rectus resection (RR) in patients with acute acquired comitant esotropia (AACE) versus common forms of esotropia and to provide dose-response reference for surgical planning in AACE.

DESIGN

Retrospective study.

PARTICIPANTS

Consecutive patients who underwent unilateral RR for AACE or common forms of esotropia correction from January 2018 to January 2022. Only patients who achieved motor and sensory success with a minimum follow-up of 3 months were analyzed.

METHODS

Group differences in the amount of medial rectus (MR) recession and lateral rectus (LR) resection were analyzed using multivariate regression models. Surgical dose responses in AACE were analyzed using multivariable regression models. Regression models were performed with and without adjustment for clinical confounders. Piecewise analysis was used to detect segmented results.

MAIN OUTCOME MEASURES

Group difference in surgical amount and dose responses of unilateral RR in AACE.

RESULTS

Fifty-four patients with AACE and 98 patients with common forms of esotropia were included. To correct comparable deviations, surgical amount performed was significant larger in AACE patients, with the adjusted group differences of 0.49 mm (95% confidence interval [CI], 0.34-0.65 mm; P < 0.001) in MR recession and 1.68 mm (95% CI, 1.25-2.11 mm; P < 0.001) in LR resection in patients with deviation < 40 prism diopters (Δ) and with a group difference of 1.22 mm (95% CI, 0.76-1.68 mm; P < 0.001) in LR resection in those with deviation ≥ 40 Δ. In AACE patients, in the adjusted model taking into account the intercept, dose responses of MR recession and LR resection in patients with deviation < 30 Δ were 5.11 Δ/mm (95% CI, 0.98-9.23 Δ/mm; P = 0.02) and 2.51 Δ/mm (95% CI, 0.57-4.45 Δ/mm; P = 0.02), respectively, and for those with deviation ≥ 30 Δ, the dose response of additional LR resection was 5.48 Δ/mm (95% CI, 4.56-6.40 Δ/mm; P < 0.001) to correct remaining deviation beyond 30 Δ.

CONCLUSIONS

These findings provide quantitative evidence that augmented-dose unilateral RR should be performed in AACE for favorable surgical outcomes. The new surgical dose calculation proposed provides reference for surgical planning.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Screening, Diagnosis, and Treatment of Pediatric Ocular Diseases

Vision is an important aspect of a child's quality of life and intellectual, social, and emotional development. Disruptions to vision during infancy and early childhood can cause lifelong vision impairment or blindness. However, early identification and treatment of eye disease can prevent loss of sight and its consequent long-term effects. Therefore, screening guidelines exist to guide physicians in detecting the most common threats to sight in the different stages of infancy and childhood. This review describes common causes of pediatric vision impairment, the recommended screening guidelines for diagnosing them, and current treatment modalities.

Differences in Inferior Oblique Muscle Satellite Cell Populations between Primary and Secondary Inferior Oblique Muscle Overaction

INTRODUCTION

The aim of the study was to compare the number of paired box 7 (PAX7)-positive, myogenic differentiation 1 (MyoD1)-positive, and neural cell adhesion molecule-1 (NCAM)-positive satellite cells in human primary versus secondary inferior oblique muscle overaction (IOOA).

METHODS

This prospective observational study enrolled patients who underwent inferior oblique muscle myectomy at the Department of Pediatric Ophthalmology and Strabismus in Tianjin Eye Hospital between January 2020 and November 2020. The muscle specimens were processed. Immunohistochemistry and immunofluorescence were used to quantify inferior oblique muscle fiber diameter and PAX7-positive, NCAM-positive, and MyoD1-positive satellite cells.

RESULTS

Thirty-eight patients with inferior oblique overaction were enrolled: 18 with primary IOOA and 20 with secondary IOOA. The participants were significantly younger in the secondary IOOA group than in the primary IOOA group (2.8 ± 1.2 vs. 9.0 ± 3.2 years, p < 0.001). The muscle fiber diameter between the two groups was not significantly different (13.5 ± 1.4 vs. 13.8 ± 0.7 µm, p = 0.530), but PAX7+ (3.3 ± 2.8 vs. 1.8 ± 0.6, p < 0.001), NCAM+ (3.6 ± 1.5 vs. 1.7 ± 0.2, p < 0.001), and MyoD1+ (4.8 ± 1.9 vs. 2.7 ± 0.5, p < 0.001) cell counts were higher in primary IOOA than in secondary IOOA.

CONCLUSIONS

PAX7pos, MyoD-1pos, and NCAMpos cell counts per laminar nucleus were almost 2-fold higher in the primary IOOA group than in the secondary IOOA group.

Development and Validation of a Nomogram for Predicting Second Surgery in Patients with Concomitant Esotropia

INTRODUCTION

This study developed and validated a nomogram for predicting the risk of second surgery in patients with concomitant esotropia (CE) based on a cohort in Beijing.

METHODS

In this retrospective cohort study, the inpatient and outpatient medical records of 419 patients with CE who underwent surgery at the Peking University First Hospital between January 1, 2005 and December 31, 2009 were collected. A total of 357 CE cases were included. For those cases 70% were randomly assigned to the training set (n = 234) and 30% to the validation set (n = 123). Demographic and clinical variables were ascertained at hospital admission and discharge and screened using multivariate Cox proportional hazards regression analysis to construct predictive models and generate a 1-, 4-, and 8-year overall survival nomogram. This nomogram provided an estimate of the risk of second surgery in patients with surgically treated CE. Internal validation was conducted using the concordance index (C-index) and calibration curve for the training and validation sets.

RESULTS

Six independent prognostic factors were identified, namely age at surgery, age at onset, amblyopia, deviation angles, surgical amount, and deviation angles 1 week after surgery, and these were entered into the nomogram. The proposed nomogram showed favorable discrimination and accuracy in the training and validation sets. The C-indexes of the training and validation sets were 0.84 (95% CI 0.79-0.89) and 0.80 (95% CI 0.78-0.82), respectively.

CONCLUSIONS

The proposed nomogram can serve as a predictive tool for prognostic evaluation of CE surgery.

Children with strabismus and amblyopia presented abnormal spontaneous brain activities measured through fractional amplitude of low-frequency fluctuation (fALFF)

Purpose

Based on fMRI technology, we explored whether children with strabismus and amblyopia (SA) showed significant change in fractional amplitude of low-frequency fluctuation (fALFF) values in specific brain regions compared with healthy controls and whether this change could point to the clinical manifestations and pathogenesis of children with strabismus to a certain extent.

Methods

We enrolled 23 children with SA and the same number matched healthy controls in the ophthalmology department of the First Affiliated Hospital of Nanchang University, and the whole brain was scanned by rs-fMRI. The fALFF value of each brain area was derived to examine whether there is a statistical difference between the two groups. Meanwhile, the ROC curve was made in a view to evaluate whether this difference proves useful as a diagnostic index. Finally, we analyzed whether changes in the fALFF value of some specific brain regions are related to clinical manifestations.

Results

Compared with HCs, children with SA presented decreased fALFF values in the left temporal pole: the superior temporal gyrus, right middle temporal gyrus, right superior frontal gyrus, and right supplementary motor area. Meanwhile, they also showed higher fALFF values in specific brain areas, which included the left precentral gyrus, left inferior parietal, and left precuneus.

Conclusion

Children with SA showed abnormal fALFF values in different brain regions. Most of these regions were allocated to the visual formation pathway, the eye movement-related pathway, or other visual-related pathways, suggesting the pathological mechanism of the patient.

Vestibulo-ocular reflex evaluation of the children with acquired esotropia

OBJECTIVES

This study aims to evaluate the effects of acquired esotropia on vestibulo-ocular reflex (VOR) gain in children using video (vHIT) and functional head impulse (fHIT) tests.

METHODS

A total of 62 children aged 6-18 years, with acquired esotropia and normal vision, were evaluated in the study. The patients were divided into two sub-groups: accommodative and non-accommodative. VOR gains were analyzed by performing lateral canal vHIT and fHIT with monocular and binocular recordings by a single examiner.

RESULTS

Seventeen (10 male, 7 female) children with accommodative esotropia, 24 (14 male, 10 female) children with non-accommodative esotropia, and 21 (8 male and 12 female) healthy controls were included in this study. The vHIT findings did not differ between the groups (p˃.05). In the non-accommodative esotropia group, the location of the camera in both binocular and monocular vHIT recordings made a significant difference in the left VOR gain (p = .025, z = -2.243, p = .032, and z = -2.143, respectively), but no difference was observed in the right VOR gain. In the accommodative esotropia group, while the camera was on the left there was a significant difference in the right VOR gain between binocular and monocular recordings (p = .016, z = -2.413) but no difference was observed in the left VOR gain. No overt or covert saccade was detected in any group.

CONCLUSIONS

The statistical differences found in vHIT and fHIT in acquired esotropia patients are thought to be sporadic and based on the results of this study no correction or change in recording technique is required for vHIT or fHIT in children with acquired esotropia.

Application of Absorbable Suture in Strabismus Correction and Nursing Management Advantage of Watson Care Theory in Perioperative Period

Objectives

The article is aimed at investigating the suture effect of absorbable suture in strabismus correction and the advantage of Watson care theory.

Methods

148 children with strabismus were enrolled in this study and divided into two groups. The control group received routine nursing, and on this basis, the observation group was given Watson care theory nursing and eye muscle suture with absorbable sutures. The degree of cooperation (induction compliance checklist (ICC) score), negative emotion (modified Yale preoperative anxiety scale (m-YAPS) score), pain (face pain scale (FPS) score), quality of nursing management, parents' satisfaction, clinical efficacy, and adverse reactions were compared.

Results

After nursing and surgical treatment, all children's strabismus symptoms were improved, and the improvement of strabismus and visual function in the observation group was more obvious. Watson care nursing can effectively improve the nursing management quality, parents' satisfaction, children's negative emotions, and treatment compliance.

Conclusions

As a result, Watson care theory nursing is of great significance for improving the relationship between nurses and patients and building a harmonious hospital.

Functional changes in the visual cortex in preoperative and postoperative patients with intermittent exotropia: study protocol for a non-randomised case-control clinical trial

INTRODUCTION

Intermittent exotropia (IXT) is the most common type of divergent squint. IXT is primarily a cortical neurologic dysfunction disorder, occurring as a result of the insufficient maintenance of sensory and motor fusion. Recent reports have demonstrated the relationship between IXT and visual cortical impairment. We planned to assess blood oxygen level-dependent (BOLD)-functional magnetic resonance imaging (fMRI) in patients with IXT during the preoperative and postoperative follow-ups to evaluate the functional changes in the visual cortex.

METHODS AND ANALYSIS

A total of 90 Chinese subjects will be recruited, and their ages will be between 18 and 40 years old. The subjects will include the surgical treatment (ST) group (45 subjects with IXT who will undergo surgery) and the HC group (45 age-matched, sex-matched and education-matched healthy volunteers). The assessments will include the following aspects: fMRI and general ophthalmic examinations, optometry measurements and strabismus-related tests, such as the ocular deviation, binocular vision test and Newcastle Control Score (NCS). Each subject will complete the resting-state BOLD-fMRI, and the sequences will include echo planar imaging (EPI) pulse and 3-dimensional brain volume (3D-BRAVO) to acquire high-resolution images. The follow-up schedule will be 6 and 12 months after the surgery. The primary outcome will be determined by cortex changes in BOLD-fMRI in the ST group before and after surgery. We will also compare the HC group with the preoperative subjects in the ST group. The secondary outcomes will be changes in strabismus-related examinations, such as binocular visual function and NCS.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Medical Ethics Committee of Beijing Tongren Hospital. We plan to publish the results of this study in a peer-reviewed journal article.

TRIAL REGISTRATION NUMBER

ChiCTR2100048852.

Comparison of Botulinum toxin type A with surgery for the treatment of intermittent exotropia in children

Background

The aim of this study was to observe the effectiveness of botulinum toxin type A (BTA) in the treatment of intermittent exotropia (IXT) in children compared with strabismus surgery.

Methods

One hundred forty-four children with a clear diagnosis of IXT and an indication for surgery were eligible for inclusion. Subjects were divided into two groups based on parental decision: the BTA injection group (injection group) or the conventional surgery group (surgery group). All cases were followed up for 6 months. The primary outcome was a comparison of the success rate (deviation between − 10 and + 10 PD) between the two groups at 6 months after the initial treatment. Secondary outcomes included change in deviation, visual function, and post-surgical complications.

Results

Seventy-two patients were enrolled in each group. At 6-month follow-up, there was no significant difference in the success rate between the injection and surgery groups (52.8% vs 66.7%, P = 0.13; postoperative deviation − 12.22 ± 10.80 PD vs − 9.17 ± 10.30 PD, P = 0.09). The binocular Visual function, except for near stereoacuity, improved after treatment in both groups, while the fusion recovery rate was higher in the surgical group (68.1% vs 95.8%, P < 0.001). Transient complications in the injection group included diplopia, ptosis, and subconjunctival hemorrhage, whereas subconjunctival hemorrhage, conjunctival edema, foreign body sensation, pain, and diplopia were seen in the surgical group. The complications of BTA were relatively mild.

Conclusions

BTA is as effective as surgery in the treatment of IXT in children, but the recovery of the fusion is lower than surgery.

Trial registration

The study has completed the clinical registration on (ChiCTR-INR-17013777).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02285-2.

An artificial intelligence platform for the diagnosis and surgical planning of strabismus using corneal light-reflection photos

Background

Strabismus affects approximately 0.8–6.8% of the world’s population and can lead to abnormal visual function. However, Strabismus screening and measurement are laborious and require professional training. This study aimed to develop an artificial intelligence (AI) platform based on corneal light-reflection photos for the diagnosis of strabismus and to provide preoperative advice.

Methods

An AI platform consisting of three deep learning (DL) systems for strabismus diagnosis, angle evaluation, and operation plannings based on corneal light-reflection photos was trained and retrospectively validated using a retrospective development data set obtained between Jan 1, 2014, and Dec 31, 2018. Corneal light-reflection photos were collected to train the DL systems for strabismus screening and deviation evaluations in the horizontal strabismus while concatenated images (each composed of two photos representing different gaze states) were procured to train the DL system for operative advice regarding exotropia. The AI platform was further prospectively validated using a prospective development data set captured between Sep 1, 2019, and Jun 10, 2020.

Results

In total, 5,797 and 571 photos were included in the retrospective and prospectively development data sets, respectively. In the retrospective test sets, the screening system detected strabismus with a sensitivity of 99.1% [95% confidence interval (95% CI), 98.1–99.7%], a specificity of 98.3% (95% CI, 94.6–99.5%), and an AUC of 0.998 (95% CI, 0.993–1.000, P<0.001). Compared to the angle measured by the perimeter arc, the deviation evaluation system achieved a level of accuracy of ±6.6º (95% LoA) with a small bias of 1.0º. Compared to the real design, the operation advice system provided advice regarding the target angle within ±5.5º (95% LoA). Regarding strabismus in the prospective test set, the AUC was 0.980. The platform achieved a level of accuracy of ±7.0º (95% LoA) in the deviation evaluation and ±6.1º (95% LoA) in the target angle suggestion.

Conclusions

The AI platform based on corneal light-reflection photos can provide reliable references for strabismus diagnosis, angle evaluation, and surgical plannings.

Detection of Referable Horizontal Strabismus in Children's Primary Gaze Photographs Using Deep Learning

PURPOSE

This study implements and demonstrates a deep learning (DL) approach for screening referable horizontal strabismus based on primary gaze photographs using clinical assessments as a reference. The purpose of this study was to develop and evaluate deep learning algorithms that screen referable horizontal strabismus in children's primary gaze photographs.

METHODS

DL algorithms were developed and trained using primary gaze photographs from two tertiary hospitals of children with primary horizontal strabismus who underwent surgery as well as orthotropic children who underwent routine refractive tests. A total of 7026 images (3829 non-strabismus from 3021 orthoptics [healthy] subjects and 3197 strabismus images from 2772 subjects) were used to develop the DL algorithms. The DL model was evaluated by 5-fold cross-validation and tested on an independent validation data set of 277 images. The diagnostic performance of the DL algorithm was assessed by calculating the accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC).

RESULTS

Using 5-fold cross-validation during training, the average AUCs of the DL models were approximately 0.99. In the external validation data set, the DL algorithm achieved an AUC of 0.99 with a sensitivity of 94.0% and a specificity of 99.3%. The DL algorithm's performance (with an accuracy of 0.95) in diagnosing referable horizontal strabismus was better than that of the resident ophthalmologists (with accuracy ranging from 0.81 to 0.85).

CONCLUSIONS

We developed and evaluated a DL model to automatically identify referable horizontal strabismus using primary gaze photographs. The diagnostic performance of the DL model is comparable to or better than that of ophthalmologists.

TRANSLATIONAL RELEVANCE

DL methods that automate the detection of referable horizontal strabismus can facilitate clinical assessment and screening for children at risk of strabismus.

Prevalence and associated risk factors for childhood strabismus in Lhasa, Tibet, China: a cross-sectional, school-based study

Background

To estimate the prevalence of strabismus and associated risk factors among grade one school children in Lhasa, Tibet, China.

Methods

The Lhasa Childhood Eye Study (LCES) was a cross-sectional, school-based childhood study conducted in Grade one students from primary schools in Lhasa, Tibet, China. Comprehensive ophthalmic examinations and basic systemic examinations were evaluated. A questionnaire survey containing information about children, as well as parents’ information, was sent to the corresponding parents of eligible children. The prevalence of strabismus and its 95% confidence interval was estimated. Univariate and multivariate logistic regression analyses were conducted to determine the associated risk factors.

Results

A total of 1942 eligible grade one students were enrolled, of which 1856 participants completed all examinations. The average age was 6.83 ± 0.46 years, 53% of participants were boys and 1762 were the Tibetan Minority. Over all, the prevalence of strabismus was 68/1856 (3.7%) (95%CI: 2.81,4.52), with no difference between the ages, genders, ethnicities and body mass index, while tilting one’s head when writing may be a risk factor for strabismus (P = 0.004). Strabismus students had mean best corrected visual acuity of 0.16 ± 0.28(LogMAR), over 50% patients with esotropia were hyperopic, and participants who had stereopsis impairments showed a significant difference between esotropia and exotropia (P = 0.026).

Conclusions

The prevalence of strabismus in LCES was 3.7%, which is higher than previous reports from Chinese childhood epidemiology studies. Strabismus is a common contributing factor to amblyopia. Tilting one’s head when writing may be a risk factor. Esotropia is more likely to affect stereopsis and be associated with the refractive state of hyperopia.

Trial registration

The study has finished the clinical registration on Chinese Clinical Trial Registry. (http://www.chictr.org.cn, ChiCTR1900026693).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-020-01732-2.

Disrupted neural signals in patients with concomitant exotropia

PURPOSE

Decreased binocular and oculomotor function in strabismics has recently been considered as cortical in origin. This study aimed to investigate functional abnormalities using a frequency-specific neuroimaging method in patients with concomitant exotropia (XT), and to demonstrate the clinical implications.

METHODS

Resting-state functional magnetic resonance imaging data were collected in 26 XT patients and 26 matched controls. To evaluate the local spontaneous neural activity, the amplitude of low frequency fluctuations (ALFF) was calculated in the typical frequency band (0.01-0.08 Hz) as well as five narrowly-defined frequency bands (slow-6: 0-0.01 Hz, slow-5: 0.01-0.027 Hz, slow-4: 0.027-0.073 Hz, slow-3: 0.073-0.167 Hz, and slow-2: 0.167-0.25 Hz), respectively.

RESULTS

Patients with XT showed decreased ALFF in the bilateral parieto-occipital sulcus (POS), and increased ALFF in the bilateral thalamus within the typical frequency band. Frequency-dependent ALFF alterations were found in the higher visual areas such as the right lateral occipital complex (LOC). Furthermore, ALFF in the right LOC in the slow-5 band was positively correlated with fusion control score (r = 0.70, p < 0.0001) and binocular function score (r = 0.67, p = 0.0002). Regression analyses showed that early age of onset remained the only significant explanatory factor for ALFF reduction in the right POS in the typically-measured frequency band (also referred to as the typical frequency band) (Odds ratio, 0.038; 95% confidence interval, 0.001 to 0.075).

CONCLUSIONS

Our findings provide spatial information regarding the functionally disrupted regions in XT. Moreover, the frequency-dependent ALLF alteration in the right LOC might reflect a potential plastic capacity in binocular function, which could be a potential objective index for evaluating disease severity.

A Randomized Clinical Trial of Immediate Versus Delayed Glasses for Moderate Hyperopia in Children 3 to 5 Years of Age

PURPOSE

To compare visual acuity (VA) and binocularity outcomes in moderately hyperopic children with normal VA and binocularity assigned to glasses versus observation.

DESIGN

Prospective randomized clinical trial (RCT).

METHODS

One hundred nineteen 3- to 5-year-old children with hyperopia between +3.00D and +6.00D spherical equivalent were randomly assigned to glasses versus observation (with glasses prescribed if deteriorated for subnormal distance VA or near stereoacuity, or manifest strabismus). Follow-up occurred every 6 months. At 3 years, the treatment strategy was classified as "failed" if any of the following were met, both with and without correction: subnormal distance VA or stereoacuity; manifest strabismus; or strabismus surgery during follow-up.

RESULTS

Of 84 (71%) children who completed the primary outcome examination, failure occurred in five (12%; 95% confidence interval [CI]: 4%-26%) of 41 assigned to glasses and four (9%; 95% CI: 3%-22%) of 43 assigned to observation (difference = 3%; 95% CI: -12%-18%; P = .72). Deterioration prior to 3 years (requiring glasses per protocol) occurred in 29% (95% CI: 19%-43%) assigned to glasses and 27% (95% CI: 17%-42%) assigned to observation.

CONCLUSIONS

In an RCT comparing glasses to observation for moderately hyperopic 3- to 5-year-old children with normal VA and binocularity, failure for VA or binocularity was not common. With insufficient enrollment and retention, our study was unable to determine whether immediate glasses prescription reduces failure rate, but low failure rates suggest that immediate glasses prescription for these children may not be needed to prevent failure for VA and/or binocularity.

LONG-TERM VARIABILITY OF STRABISMUS ANGLE IN NEUROLOGICALLY IMPAIRED PREMATURE INFANTS: A 12-YEAR FOLLOW UP

The aim of this retrospective study was to determine the strabismus angle variability and rationality of surgical treatment of strabismus in prematurely born children with neurological impairment during 12-year follow up. Eleven premature infants born in 2003 were included in the study and treated with equal conservative approach from 2005 until 2016. Initial esotropia was found in seven and exotropia in four of eleven children. Changes in the strabismus angle correlated significantly with aging of the children. In children with initial esotropia, the strabismus angle became less convergent (less positive), changed the orientation and became more divergent with aging. In those with initial exotropia, the angle became less divergent (more positive), changed the orientation and became more convergent. Moreover, a significant difference in the strabismus angle was found during the 12-year follow up. Based on our results, due to the variability in strabismus angle, we did not find enough evidence for optimal timing or rationality of strabismus surgery in neurologically impaired children born prematurely.

A Randomized Clinical Trial of Immediate versus Delayed Glasses for Moderate Hyperopia in 1- and 2-Year-Olds

PURPOSE

Two strategies were compared for managing moderate hyperopia without manifest strabismus among 1- and 2-year-old children: (1) immediate prescription of glasses versus (2) observation without glasses unless reduced distance visual acuity (VA), reduced stereoacuity, or manifest strabismus.

DESIGN

Prospective randomized clinical trial.

PARTICIPANTS

A total of 130 children aged 1 to 2 years with hyperopia between +3.00 diopters (D) and +6.00 D spherical equivalent (SE) in at least 1 eye, anisometropia ≤1.50 D SE, and astigmatism ≤1.50 D based on cycloplegic refraction and no manifest strabismus.

METHODS

Participants were randomly assigned to glasses (1.00 D less than full cycloplegic hyperopia) versus observation and followed every 6 months for 3 years. Glasses were prescribed to those assigned to observation if they met prespecified deterioration criteria of distance VA or near stereoacuity below age norms, or development of manifest strabismus.

MAIN OUTCOME MEASURES

At the 3-year primary outcome examination, participants were classified as failing the randomized management regimen if distance VA or stereoacuity was below age norms or manifest strabismus was observed (each with and without correction in trial frames, confirmed by masked retest, irrespective of whether deterioration had occurred previously), or if strabismus surgery had been performed.

RESULTS

Of the 106 participants (82%) completing the 3-year primary outcome examination, failure occurred in 11 (21%) of 53 in the glasses group and 18 (34%) of 53 in the observation group (difference = -13%; 95% confidence interval [CI], -31 to 4; P = 0.14). Sixty-two percent (95% CI, 49-74) in the observation group and 34% (95% CI, 23-48) in the glasses group met deterioration criteria (requiring glasses if not wearing).

CONCLUSIONS

For 1- and 2-year-olds with uncorrected moderate hyperopia (+3.00 D to +6.00 D SE), our estimates of failure, after 3 years of 6-month follow-ups, are inconclusive and consistent with a small to moderate benefit or no benefit of immediate prescription of glasses compared with careful observation (with glasses only if deteriorated).