Patient perspectives on their outcomes from strabismus surgery undertaken for psychosocial reasons.

BACKGROUND: Strabismus surgery undertaken for psychosocial reasons aims to align the eyes in a straighter position, reduce the psychosocial symptoms experienced and improve health related quality of life (HRQoL). Greater evidence of the postoperative outcomes in adults undergoing strabismus surgery for psychosocial reasons is required to inform funding and commissioning decisions about strabismus surgery. METHODS: Semi-structured interviews were conducted with adults who had previously undergone strabismus surgery for psychosocial reasons to explore their perceptions of their postoperative outcomes. Maximum variation sampling was used to recruit males and females, younger and older participants. Interviews were transcribed and analysed using thematic analysis following the principles of grounded theory. RESULTS: Thirteen adults were recruited and interviewed, mean 12.2 months postoperatively (range 4.5-20 months). Participants reported a range of improvements in vision, task performance, physical symptoms and confidence and emotions. Some worsening of physical symptoms was reported. CONCLUSION: Despite undergoing strabismus surgery for psychosocial reasons, a range of improvements in vision, task performance and physical symptoms were reported by adult patients postoperatively, in addition to the expected improvements in confidence and emotions.

Schizophrenia and Orthoptic Conditions: A Literature Review.

Purpose: A narrative review of the literature reporting ocular abnormalities in patients with schizophrenia was undertaken to determine the types and prevalence of orthoptic conditions in this patient cohort. Methods: A systematic search of multiple databases yielded 1,974 studies published between January 1992 and January 2022. All were screened for relevance based on their title and abstract. Results: Seventeen studies were included in the final review. Ocular abnormalities reported in schizophrenia included a high incidence of strabismus, reduced visual acuity and reduced stereopsis compared to controls. Additionally, eye movement abnormalities (including reduced smooth pursuit gain and increased prosaccade latency) were frequently reported. Reduced visual acuity was associated with negative symptoms and reduced quality of life in schizophrenia. Conclusions: Orthoptists and eye care professionals should be aware that a higher incidence of strabismus, reduced visual acuity, reduced stereoacuity, and eye movement abnormalities are reported in patients with schizophrenia. Further research is required to determine whether, or to what extent, ocular abnormalities and visual disturbances influence or exacerbate the symptoms of schizophrenia, and whether there is an effect of schizophrenia medication on these orthoptic conditions.

Strabismus Surgery for Psychosocial Reasons-A Literature Review.

Introduction: Strabismus surgery may be undertaken for visual benefit, to improve or eliminate diplopia symptoms, or to restore or improve binocular single vision (BSV). In patients without visual symptoms or expected visual benefit, strabismus surgery may still be undertaken if the presence of strabismus causes the patient psychosocial symptoms. To evaluate strabismus surgery undertaken for psychosocial reasons, evidence of postoperative outcomes in this specific cohort is needed. Methods: A systematic search of the literature was conducted (1946-2023) to identify evidence where postoperative outcomes were reported for adult patients (age 18 years and above) who had undergone strabismus surgery for psychosocial reasons. Results: Sixty-nine papers were included in the literature review. Most sources of evidence included patients within heterogeneous cohorts of strabismus surgery outcomes, with a range of symptoms and differing surgical aims. Discussion: In adults who underwent strabismus surgery for psychosocial reasons, improved postoperative ocular alignment and/or improved health related quality of life (HRQoL) were common. Strabismus surgery outcomes appeared to be measured satisfactorily at three months postoperatively. Additional surgical outcomes, including an expanded field of vision, unexpected BSV, improved binocular summation, improved task performance and improved eye movements have been reported, but not fully investigated. There was a lack of consensus on how postoperative success should be defined and measured. A core outcome set for strabismus has been suggested and there is potential to add to the available evidence by investigating which outcome measures are most relevant to those with strabismus and psychosocial symptoms. There is a growing need for robust evidence in this specific subgroup of patients due to a lack of evidence specifically reporting postoperative outcomes in adults with strabismus and psychosocial symptoms.

The Assessment of Vision in Children with Severe Learning Difficulties: A Systematic Review.

Background: Children with learning difficulties that require a vision assessment may not be able to perform standard clinical vision tests, for example, Forced Choice Preferential Looking (FCPL). There is a lack of standardisation on the procedure of vision assessment in this group of children. The aim of this literature review was to identify and evaluate methods of vision assessment when standard clinical vision tests are not possible in children with severe learning difficulties. Method: Three databases (CINAHL, PubMed, Web of Science) were searched from inception to Nov 2022 for methods of vision assessment in children with learning difficulties. Reference lists and grey literature were also searched. The McMaster University Critical review form for quantitative studies was used to assess the methodological quality of the primary studies identified. Results: Five-hundred and seventy one papers were identified from databases and 16 were identified from searching reference lists and grey literature. Of the 587, five studies were relevant and fulfilled all the inclusion and exclusion criteria. Three methods of vision assessment were identified: Visually Evoked Potentials (VEP), questionnaires, and the Bradford visual function box (BVFB). Discussion: The VEP method was validated and reliable, although it had a similar success rate to the standardised FCPL tests in children with learning difficulties. The BVFB was a standardised method for measurement of vision threshold in children that cannot successfully complete FCPL tests, however it has not been validated. Questionnaires are an efficient way to gather descriptive information on the child's functional vision, however no guidance on the interpretation of the information is available. The BVFB and questionnaires require further development and validation. All three methods (VEP, questionnaires, and BVFB) can be useful as part of the assessment of vision in a child with severe learning difficulties where standard clinical tests are not possible, when used in a standardised manner.

Is there value in measuring near visual acuity during occlusion therapy for amblyopia?

Introduction: The purpose of this study was to investigate near and distance visual acuity (VA) prior to, during and on completion of occlusion therapy for amblyopia. Method: Fifty-four patients aged 4-7 years (mean 4.9; ±0.44) with untreated strabismic, anisometropic or mixed amblyopia were recruited to the study following refractive adaptation where applicable. All patients underwent conventional occlusion (patching). Uniocular near and distance VA was tested using age and ability appropriate Crowded LogMAR VA tests prior to, during and upon conclusion of occlusion therapy. Results: In amblyopic eyes, there was no significant difference between near and distance VA prior to occlusion therapy with LogMAR Crowded (p = .66; mean distance VA at 3 m = 0.6 LogMAR; mean near VA at 40 cm = 0.58 LogMAR), or with LogMAR Crowded Kay Picture test (p = .78, mean distance VA at 3 m = 0.44 LogMAR; mean near VA at 33 cm = 0.46 LogMAR;). No significant difference was found between near and distance VA at any visit during occlusion therapy, or on completion of occlusion therapy with LogMAR Crowded (p = .86, mean final distance VA at 3 m = 0.266 LogMAR; mean final near VA at 40 cm = 0.25 LogMAR) or LogMAR Crowded Kay Pictures (p = .74, mean final distance VA at 3 m = 0.16 LogMAR; mean final near VA at 33 cm = 0.16 LogMAR). There was no significant difference in the VA of the fellow (non-amblyopic) eyes prior to and on completion of occlusion therapy with LogMAR Crowded at distance (3 m) or near (40 cm) (p = .05, p = .40 respectively); or with LogMAR Crowded Kay Pictures at distance (3 m) or near (33 cm) (p = .89, p = .35 respectively). Discussion: Improvement in VA of amblyopic eyes did not significantly differ between near and distance testing proximites at any point during the course of occlusion therapy for amblyopia in our study. These findings may aid clinicians with appropriate test selection and help with clinical time pressures. Where patient concentration does not allow for uniocular distance vision, uniocular near vision may be used to diagnose amblyopia, and vice versa. This could prevent delay in the treatment of amblyopia.

Minimal reporting guideline for research involving eye tracking (2023 edition).

A guideline is proposed that comprises the minimum items to be reported in research studies involving an eye tracker and human or non-human primate participant(s). This guideline was developed over a 3-year period using a consensus-based process via an open invitation to the international eye tracking community. This guideline will be reviewed at maximum intervals of 4 years.

Evaluation of the Nystagmus Information Pack.

Introduction: In response to the need for easily accessible, high-quality information about nystagmus, the Nystagmus Information Pack was created and made freely available online in 2017. This study was undertaken to evaluate the content and accessibility of the Nystagmus Information Pack. Methods: Clinicians, eye clinic liaison officers (ECLOs), teachers, patients, families, and any person with an interest in nystagmus were invited to complete an online questionnaire about the content and accessibility of the Nystagmus Information Pack. Results: One hundred and sixty respondents completed the questionnaire. Respondents who had previously accessed the Nystagmus Information Pack (n = 49, 30.6%) reported the content was appropriate (86%), of sufficient detail (94%), and easy to understand (88%). Minor suggestions were made to improve the content. Respondents who had not accessed the Nystagmus Information Pack (n = 111, 69.4%) reported not being aware of the resource (90%) but had already accessed nystagmus information from a wide range of sources. Poor vision was a barrier to accessing the resource for a small number of respondents (4.5%). Conclusion: Some improvements to the content and accessibility of the Nystagmus Information Pack should be considered, in particular the format options in which it is available, to enable access in preferred formats and with poor vision. The availability of the Nystagmus Information Pack should be promoted and shared more widely, as the majority of respondents were unaware of the resource despite having an association with or interest in nystagmus.

Is a Depth Camera in Agreement with an Electromagnetic Tracking Device when Measuring Head Position?

INTRODUCTION: Clinicians typically observe and describe abnormal head postures (AHPs) and may also measure them. Depth cameras have been suggested as a reliable measurement device for measuring head position using face-tracking technology. This study compared a depth camera (Microsoft Kinect) to a gold standard electromagnetic tracking system (Polhemus device) to measure head position. METHOD: Twenty healthy volunteers (mean age 21 years) had their head position simultaneously recorded using the depth camera (Kinect) and the electromagnetic tracking system (Polhemus). Participants were asked to make 30-degree head movements into chin up, chin down, head turn and head tilt positions. The head movement made and the stability of the head at each position were recorded and analysed. RESULTS: Compared to the electromagnetic tracking system (Polhemus), the depth camera (Kinect) always measured a smaller head movement. Measurements with the two devices were not statistically significantly different for turn right (P = 0.3955, p > 0.05), turn left (P = 0.4749, p > 0.05), tilt right (P = 0.7086, p > 0.05) and tilt left (P = 0.4091, p > 0.05) head movements. However, the smaller depth camera measurement of chin up and chin down head movements were statistically significant, chin up (P = 0.0001, p < 0.01) and chin down (P = 0.0005, p < 0.001). At each eccentric position, the depth camera (Kinect) recordings were more variable than the electromagnetic tracking system (Polhemus). CONCLUSIONS: Compared to the electromagnetic tracking system (Polhemus), the depth camera (Kinect) was comparable for measuring head turns and tilts but was less accurate at measuring chin up and chin down head positions. Further research is needed before the depth cameras are considered for clinical recordings of head position.

Analysing nystagmus waveforms: a computational framework.

We present a new computational approach to analyse nystagmus waveforms. Our framework is designed to fully characterise the state of the nystagmus, aid clinical diagnosis and to quantify the dynamical changes in the oscillations over time. Both linear and nonlinear analyses of time series were used to determine the regularity and complexity of a specific homogenous phenotype of nystagmus. Two-dimensional binocular eye movement recordings were carried out on 5 adult subjects who exhibited a unilateral, uniplanar, vertical nystagmus secondary to a monocular late-onset severe visual loss in the oscillating eye (the Heimann-Bielschowsky Phenomenon). The non-affected eye held a central gaze in both horizontal and vertical planes (± 10 min. of arc). All affected eyes exhibited vertical oscillations, with mean amplitudes and frequencies ranging from 2.0°-4.0° to 0.25-1.5 Hz, respectively. Unstable periodic orbit analysis revealed only 1 subject exhibited a periodic oscillation. The remaining subjects were found to display quasiperiodic (n = 1) and nonperiodic (n = 3) oscillations. Phase space reconstruction allowed attractor identification and the computation of a time series complexity measure-the permutation entropy. The entropy measure was found to be able to distinguish between a periodic oscillation associated with a limit cycle attractor, a quasiperiodic oscillation associated with a torus attractor and nonperiodic oscillations associated with higher-dimensional attractors. Importantly, the permutation entropy was able to rank the oscillations, thereby providing an objective index of nystagmus complexity (range 0.15-0.21) that could not be obtained via unstable periodic orbit analysis or attractor identification alone. These results suggest that our framework provides a comprehensive methodology for characterising nystagmus, aiding differential diagnosis and also permitting investigation of the waveforms over time, thereby facilitating the quantification of future therapeutic managements. In addition, permutation entropy could provide an additional tool for future oculomotor modelling.

How Does Vertical Reading Affect Reading Speed?

PURPOSE: Vertical reading is an adaptive reading strategy sometimes used in homonymous hemianopia. This study aimed to measure horizontal and vertical reading speeds in visually normal volunteers using the Radner Reading Chart. METHODS: Fifteen orthoptic students, mean age 19.7 years, took part in this repeated measures study. Participants read sentences aloud from the Radner Reading Chart horizontally and rotated vertically, to read up and down the line. Words read correctly and the time taken to read each sentence were recorded. RESULTS: Reading speeds were calculated (words read correctly per second) for horizontal text (2.95 words per second) and for vertical text, reading up the line (1.73 words per second) and reading down the line (1.57 words per second). Reading horizontal text was significantly faster than reading vertical text. Reading horizontal text was 1.22 words per second faster than reading text vertically up (p < 0.0001) and 1.38 words per second faster than text vertically down (p < 0.0001). There was no statistically significant difference between reading text vertically up the line and vertically down the line (0.16 words per second, p = 0.42). CONCLUSION: Horizontal reading speed, measured with the Radner Reading Chart, was significantly faster than both vertical reading speeds. There was no significant difference between reading vertically up the line and reading vertically down the line. The slower time taken to read the vertically orientated sentences had a greater effect on reading speed than the number of errors made.

Using VR to Investigate the Relationship between Visual Acuity and Severity of Simulated Oscillopsia.

PURPOSE: Oscillopsia is a debilitating symptom resulting from involuntary eye movement most commonly associated with acquired nystagmus. Investigating and documenting the effects of oscillopsia severity on visual acuity (VA) is challenging. This paper aims to further understanding of the effects of oscillopsia using a virtual reality simulation. METHODS: Fifteen right-beat horizontal nystagmus waveforms, with different amplitude (1°, 3°, 5°, 8° and 11°) and frequency (1.25 Hz, 2.5 Hz and 5 Hz) combinations, were produced and imported into virtual reality to simulate different severities of oscillopsia. Fifty participants without ocular pathology were recruited to read logMAR charts in virtual reality under stationary conditions (no oscillopsia) and subsequently while experiencing simulated oscillopsia. The change in VA (logMAR) was calculated for each oscillopsia simulation (logMAR VA with oscillopsia - logMAR VA with no oscillopsia), removing the influence of different baseline VAs between participants. A one-tailed paired t-test was used to assess statistical significance in the worsening in VA caused by the oscillopsia simulations. RESULTS: VA worsened with each incremental increase in simulated oscillopsia intensity (frequency x amplitude), either by increasing frequency or amplitude, with the exception of statistically insignificant changes at lower intensity simulations. Theoretical understanding predicted a linear relationship between increasing oscillopsia intensity and worsening VA. This was supported by observations at lower intensity simulations but not at higher intensities, with incremental changes in VA gradually levelling off. A potential reason for the difference at higher intensities is the influence of frame rate when using digital simulations in virtual reality. CONCLUSIONS: The frequency and amplitude were found to equally affect VA, as predicted. These results not only consolidate the assumption that VA degrades with oscillopsia but also provide quantitative information that relates these changes to amplitude and frequency of oscillopsia.

Amblyopia treatment and quality of life: the child's perspective on atropine versus patching.

Background: The impact on children of patching versus atropine treatment for amblyopia was assessed using children's perspective Health-Related Quality of Life (HRQoL) scores in 5 to 7-year olds. Methods: Forty-six children on the threshold of commencing either patching or atropine treatment for amblyopia were recruited. Treatment was prescribed for uniocular amblyopia of visual acuity (VA) 0.2 logMAR or worse. After four weeks of their chosen treatment, each child completed the Child Amblyopia Treatment Quality-of-Life Questionnaire (CAT-QoL). The Pediatric Quality of Life Inventory (PedsQL™), Young Child (5-7) Self-Report version, was completed before and after four weeks of treatment. Quality of life scores were compared between the two treatment groups. Results: Sixty-one percent (n = 28) of participants were male and 56.5% (n = 26) were white British. The CAT-QoL has a range of 0-16, with 16 being the worst quality of life. No significant difference was found between the patching group (n = 30, mean age 69.7 months) and the atropine group (n = 16, mean age 69.3 months) for CAT-QoL quality of life scores (Patch median = 6.3, Atropine median = 5.6, U = 199, p = .341, 95% CI of the median difference of -2.3 to 0.9). The Young Child (5-7) Self-Report version of the PedsQL™ has a 'total score' range of 0-100, with 0 being the worst quality of life. There was also no significant difference in PedsQL™ quality of life total scores (Patch median = 80, Atropine median = 83.33, U = 239.5, p = .991, 95% CI of the median difference -13.33 to 10) after four weeks of treatment. Conclusion: Amblyopic children reported that patching and atropine treatments did not have a significant impact on their quality of life. Patching and atropine should continue to be offered as first-line treatments for amblyopia, as children appear to tolerate both well and do not favor one over the other.

The Impact of Diplopia on Reading.

AIM: To compare the effect of induced vertical diplopia (small and large separation) on reading speed and accuracy. METHODS: The Radner Reading Chart (RRC) was used to measure reading speed (correct words per minute (wpm)) and accuracy (percentage). Accuracy was measured using two different methods: 'accuracy-omission' where only the omission of a word reduced the score, and 'accuracy-addition and omission' where any error reduced the score. Three viewing conditions were created using Fresnel prisms on plano glasses: a control condition without diplopia (6 prism dioptres (Δ) base up (BU) over each eye), small separation vertical diplopia (3Δ BU right eye and 3Δ base down (BD) left eye) and large separation vertical diplopia (6Δ BU right eye and 6Δ BD left eye). Viewing conditions were counterbalanced to minimise order effects. RESULTS: Twenty-four participants were included with a mean age of 20.1 years. The mean reading speed in the control condition was 156.90 wpm. Both diplopic conditions significantly reduced the reading speed compared to the control condition, small separation diplopia to 62.75 wpm (p < 0.001) and large separation diplopia to 105.71 wpm (p < 0.001). The mean reading speed with small separation diplopia was significantly slower than the mean reading speed with large separation diplopia (p < 0.01). Median accuracy scores in the control and the large separation diplopia conditions were 100% using both methods of measuring accuracy. The small separation diplopia condition significantly reduced accuracy to 92.86% (accuracy-omission method) and to 57.50% (accuracy-addition and omission method) compared to the control condition (p < 0.01) and the large separation diplopia condition (p < 0.05). CONCLUSION: When vertical diplopia was induced using Fresnel prisms, diplopia of smaller separation resulted in the greatest reduction in reading speed and accuracy, compared to without diplopia and large separation diplopia.

The Provision of Patient Information about Nystagmus.

AIMS: The aims of this study were to evaluate the current provision of patient information about nystagmus in orthoptic clinics in the UK and Ireland and to develop a standardised information pack about nystagmus. METHODS: A questionnaire was circulated to orthoptists in the UK and Ireland asking whether they had information to provide to patients with nystagmus, what was included in this information and how it could be improved. Orthoptists were also asked what should be included in a standardised information pack about nystagmus. RESULTS: Two hundred and thirty three orthoptists completed the questionnaire. One-third of responding orthoptists did not have information to provide to patients with nystagmus. Most reported the information available to them included details of support services and physical symptoms. Including information about living with nystagmus at different ages and long-term prognosis were the most common suggestions to improve information about nystagmus. More than half of orthoptists selected all the suggested topics to be included in a standardised information pack, with support services and long-term prognosis most frequently selected. CONCLUSIONS: Only 67% of responding orthoptists had information about nystagmus to give to patients or their families. Ways to improve the current information and content considered important by orthoptists were taken into account to create a nystagmus information pack, which is now available online.

Simulation of Oscillopsia in Virtual Reality.

PURPOSE: Nystagmus is characterised by involuntary eye movement. A proportion of those with nystagmus experience the world constantly in motion as their eyes move: a symptom known as oscillopsia. Individuals with oscillopsia can be incapacitated and often feel neglected due to limited treatment options. Effective communication of the condition is challenging and no tools to aid communication exist. This paper describes a virtual reality (VR) application that recreates the effects of oscillopsia, enabling others to appreciate the condition. METHODS: Eye tracking data was incorporated into a VR oscillopsia simulator and released as a smartphone app - "Nystagmus Oscillopsia Sim VR". When a smartphone is used in conjunction with a Google Cardboard headset, it presents an erratic image consistent with oscillopsia. The oscillopsia simulation was appraised by six participants for its representativeness. These individuals have nystagmus and had previously experienced oscillopsia but were not currently symptomatic; they were therefore uniquely placed to judge the app. The participants filled in a questionnaire to record impressions and the usefulness of the app. RESULTS: The published app has been downloaded ~3700 times (28/02/2018) and received positive feedback from the nystagmus community. The validation study questionnaire scored the accuracy of the simulation an average of 7.8/10 while its ability to aid communication received 9.2/10. CONCLUSION: The evidence indicates that the simulation can effectively recreate the sensation of oscillopsia and facilitate effective communication of the symptoms associated with the condition. This has implications for communication of other visual conditions.

The incidence and visual acuity outcomes of children identified with ametropic amblyopia by vision screening.

PURPOSE: To determine the incidence of ametropic amblyopia within a vision screening program's population and report the visual acuity outcomes of children identified with the condition. METHOD: The medical records of children who underwent vision screening as their first assessment at 4-5 years of age between September 1, 2005 and August 31, 2006, were retrospectively reviewed. Children referred with ≤0.30 logMAR in each eye with at least 1 year of follow-up had their hospital notes reviewed and data on final visual acuity, refractive error, and follow-up period collected. RESULTS: A total of 33 children identified as having ametropic amblyopia with a follow-up of at least 1 year. The incidence of ametropic amblyopia was 2%-3.2%, depending on the definition used. The mean visual acuity achieved after treatment was 0.12 logMAR, which is significantly less than the age-appropriate mean of 0.00 logMAR (P < 0.01). CONCLUSIONS: Ametropic amblyopia responds to treatment, but most children demonstrate persistent reduced visual acuity at age 7 years. The incidence of ametropic amblyopia within a routine vision screening population shows that significant numbers fail to self-present.

Decompensating esophoria as the presenting feature of myasthenia gravis.

Myasthenia gravis is a disease in which antibodies directed at nicotinic acetylcholine receptors are produced, leading to a deficiency of acetylcholine receptors at the neuromuscular junction. This results in impairment of muscular excitation, which appears clinically as fatigable muscle weakness. Weakness of the extraocular muscles occurs in nearly 90% of all myasthenics at disease onset, with ptosis being the most common presenting feature. Myasthenia gravis affecting one or a combination of the extraocular muscles without ptosis is less common; however, cases such as bilateral internuclear ophthalmoplegia without ptosis have been described in the literature. The authors present a case in which decompensating esophoria was the presenting feature of myasthenia gravis.