Near Point Of Convergence Research Articles

Is near point of convergence associated with symptom profiles or recovery in adolescents after concussion?

Our purpose was to compare the clinical and injury characteristics of concussion patients with a receded near point of convergence (NPC) vs those without a receded NPC. Concussion patients were seen within 14 days of injury. We compared those with receded a NPC (>6 cm) break point distance and those with a normal NPC distance on symptom, behavioral, and clinical assessments. We also compared NPC break points between those who did/did not recover within 28 days of injury. 123 patients completed the assessment. 77/123 (63%) of participants demonstrated a receded NPC when tested within 14 days of injury. Those with receded a NPC break point (n = 77; mean = 14.9, SD = 1.5 years; 47% female) were significantly younger than those with a normal NPC break point (n = 46; mean = 15.7, SD = 1.7 years; 46% female). The receded NPC break point group had a significantly greater proportion of patients reporting headaches (86% vs. 61%), as well as significantly greater cognitive (mean = 13.4, SD = 8.7 vs. mean = 8.8, SD = 8.6), somatic (mean = 10.0, SD = 5.9 vs. mean = 6.9, SD = 6.6), and overall (mean = 23.7, SD = 13.6 vs. mean = 15.8, SD = 14.4) symptom severity. Our multivariable model indicated among all potential predictor variables, more severe somatic symptoms were significantly associated with a greater NPC break point (β = 0.26; 95% CI = 0.01, 0.52). The group who went onto experience persistent symptoms had a significantly greater NPC break point at initial evaluation than those without persistent symptoms (mean = 9.7, SD = 7.5 cm vs. mean = 7.0, SD = 4.0 cm). Those with a receded NPC break point at initial evaluation showed an increased symptom burden, most notable with somatic symptoms, compared with those without a receded NPC break point.

The relationship between headache and convergence insufficiency

Convergence insufficiency (CI) is a common dysfunction of binocular vision. The prevalence of Convergence Insufficiency varies widely ranging from 2% to 27%. The role of CI as a cause of headache is neglected often. In this study, the association between Convergence insufficiency and Headache was being evaluated. Aim: To assess the prevalence of Convergence Insufficiency in headache patients. Materials and Methods: A prospective descriptive study included 84 patients in the age group 5 - 36 years with complaints of headache. After taking detailed history about headache pattern and asthenopic symptoms, complete ocular evaluation of both anterior and posterior segment examination, Refraction and Binocular vision assessment was done. Data was analysed by Percentage and Chi square test. Results: In this study, the prevalence of Convergence Insufficiency was 26.2% among headache patients CI was more common in female patients (63.6%) than in male patients (36.4%). 72.8% of CI was seen in young patients in the age group 10 – 29 years. Frontal headache (78.7%) and Astigmatism (45.5%) was frequently associated with CI. Increase in the Near Point of Convergence (NPC) value and decrease in the value of Base out Prism was associated with asthenopic symptoms in CI patients. Conclusion: Convergence Insufficiency is frequently associated with headache especially in younger patients. In this electronic era, the demand for near work has increased. Apart from thorough refractive evaluation, binocular vision assessment is also important in younger patients presenting with headache. Keywords: Asthenopia, Convergence, Astigmatism, Headache.

Vergence, accommodation, and visual tracking in children and adolescents evaluated in a multidisciplinary concussion clinic

Many patients with concussion experience visual symptoms following injury that lead to a diagnosis of convergence insufficiency, accommodative insufficiency, or saccadic dysfunction. However, these diagnostic categories are based on aggregates of clinical tests developed from a non-concussed population and therefore may not accurately describe visual deficits in the concussed population. Thus, we sought to understand individual metrics of visual dysfunction in chronically symptomatic post-concussion patients. This retrospective cross-sectional study included patients examined at the multidisciplinary concussion clinic (MDCC) at Boston Children’s Hospital over four years. Patients aged 5–21 years who had a complete assessment of eye alignment, vergence, accommodation, and visual tracking, and had visual acuity better than or equal to 20/30 in each eye were included. Patients with history of amblyopia, strabismus, or ocular pathology were excluded. Chart review yielded 116 patients who met inclusion criteria (median age 15 years, 64% female). The majority of patients (52%) experienced a single concussion and most were sports-related (50%). Clinical data show vergence, accommodation, or visual tracking deficits in 95% of patients. A receded near point of convergence (NPC, 70/116) and reduced accommodative amplitude (63/116) were the most common deficits. Both NPC and accommodative amplitude were significantly correlated with one another (r = −0.5) and with measures of visual tracking (r = −0.34). Patients with chronic post-concussion symptoms show deficits in individual metrics of vergence, accommodation and visual tracking. The high incidence of these deficits, specifically NPC and accommodative amplitude, highlights the need for a detailed sensorimotor evaluation to guide personalized treatment following concussion.

Utility of Ocular Motility Tests in Orbital Floor Fractures with Muscle Entrapment That is Not Detected on Computed Tomography.

PurposeDetermine the usefulness of ocular motility testing to detect the presence of muscle entrapment.Materials and MethodsCross-sectional study of patients with symptoms of diplopia secondary to facial trauma. Inclusion criteria: age between 20 and 80 years; symptoms of diplopia following facial trauma; presence of orbital floor fracture confirmed radiologically; presence of muscle entrapment confirmed at the time of surgery; best-corrected visual acuity of 0.6 or more. Exclusion criteria: muscle entrapment visible on computed tomography; candidate for immediate surgical correction; prior history of strabismus surgery. Outcome measures: Abnormal Head Position (AHP), Hirschberg Corneal Reflexes (CR), Cover/Uncover and Alternating Cover Test, Hertel exophthalmometry, Near Point of Convergence (NPC), Kestenbaum Limbus test, Red Filter test, and Hess screen test.ResultsForty-six subjects (38 males, 8 females, mean age 27 ± 3.3 SD years). Pre-operative assessment: forty-six (100%) reported diplopia on the Red Filter test and showed some degree of abnormality on the Hess Screen test. Forty-two (91%) showed AHP. Forty-one (89%) had exophthalmometry values that differed 2 mm or more between the two eyes and insufficient NPC. Thirty-two (69.6%) showed deficits of 3 mm or more on the Kestenbaum Limbus test. Sixteen (35%) had abnormal Hirschberg corneal reflexes. Eleven (24%) demonstrated constant or intermittent strabismus.ConclusionOcular motility testing can differentiate non-invasively, pre-operatively, and cost-effectively the presence of muscle entrapment even when this is not visible on computed tomography.

Parkinson's disease and convergence insufficiency: a mini-review

Background: A key manifestation of Parkinson’s disease (PD) is visual impairment. Cognitive impairment has been found to overlap with convergence insufficiency (CI) in patients with PD and is associated with significantly greater near point convergence (NPC) distance. Difficulty in reading and diplopia were the most common symptoms of CI in PD. The prevalence of CI is greater among patients with PD. Therefore, this study aimed to assess the relationship between PD and CI.
 Methods: Studies that had included data on CI, NPC, or both were selected by searching PubMed/MEDLINE and clinicaltrails.gov, without any timeline or language limitation. The following terms were used in PubMed/MEDLINE search: ‘Clinical Trials’, ‘Parkinson’s Disease’, and ‘Convergence Insufficiency’. For clinical trials.gov database, the terms ‘Parkinson’s Disease’, ‘Convergence Insufficiency’, and ‘Completed Studies’ were used. Only those studies with control subjects were included. PubMed/MEDLINE search yielded 1,563 articles, but no article was found in the clinical trails.gov search. Twelve articles met the inclusion criteria, among which nine articles were selected as they had data on CI or NPC distance (cm), and PD. 
 Results: Overall, there were 1,563 articles; among them, 12 articles met the inclusion criteria. Nine articles were selected based on their data concerning CI or NPC distance (cm) and PD. Relative to the control group, the PD group had high CI. In addition, PD group showed increase in NPC distance than the control group.
 Conclusions: These data suggest that the patients with PD had an increased likelihood of developing CI visual symptoms, and increased NPC distance than healthy controls. These findings indicate that regular eye examination is very important for patients with PD.

Frequency of oculomotor disorders in adolescents 11 to 17 years of age with concussion, 4 to 12 weeks post injury

The purpose of the study was to determine the frequency of vision diagnoses after concussion in adolescents and evaluate the sensitivity and specificity of physician-administered screening for detecting convergence and accommodative disorders post-concussion. We enrolled participants 11 to 17 years old, assessed 4 to 12 weeks following a diagnosed concussion. During the initial concussion examination, a sports medicine physician measured the near point of convergence (NPC), monocular accommodative amplitude (AA), and symptoms using the Convergence Insufficiency Symptom Survey (CISS). A comprehensive oculomotor evaluation was performed by an optometrist. One hundred and thirteen adolescents were enrolled, with a mean age of 15.2 years. Seventy-nine of the 113 (70%) participants had at least one oculomotor diagnosis after concussion, with the most common problems being vergence disorders (60%) and accommodative disorders (57%). The most common vergence disorder was convergence insufficiency (35%). Among accommodative disorders, the most common problem was accommodative insufficiency (35%). In all, 47% of the participants had more than one oculomotor diagnosis following concussion. The sensitivity of physician screening using measures of NPC, AA, and CISS for detecting convergence and accommodative insufficiency was 63%, 43%, 48%, respectively. The results of this study provide additional evidence that vision problems are common in adolescents with persistent concussion symptoms in the sub-acute phase 4 to 12 weeks post-concussion, and current physician screening methods using the NPC, AA, or the CISS underperform. Thus, it is prudent that adolescents with post-concussion symptoms lasting more than 4 weeks post injury receive a comprehensive oculomotor examination.

Longitudinal Vestibular and Oculomotor Impairments Among Amateur Athletes 1 Year Following Sport-Related Concussion: A Prospective Follow-Up.

To investigate (i) the presence of vestibular and oculomotor impairments and (ii) the self-perceived effects of concussion-associated dizziness on health-related quality of life among amateur athletes 6 months and 1 year following sport-related concussion compared with nonconcussed, control athletes. Prospective, matched-cohort study. Clinical assessment laboratory. Amateur athletes who were diagnosed with sport-related concussion within 1 week of injury, and sex-, age-, and activity-matched nonconcussed, control athletes. Participants were evaluated 6 months and 1 year following sport-related concussion and enrollment in the longitudinal study using the Vestibular and Oculo-Motor Screening and the Dizziness Handicap Inventory. We performed multivariate analyses of variance and chi-square analyses to compare concussion and control group scores at each study assessment. Forty-seven participants with concussion and 47 control participants completed the study. The concussion group reported similar mean symptom provocation scores on the Vestibular and Oculo-Motor Screening and exhibited a similar near-point convergence distance compared with the control group at the 6-month and 1-year study assessments. The concussion and control groups had similar perceptions of the effects of dizziness on their health-related quality of life at both study assessments. Meaningful differences in vestibular and oculomotor symptom provocation and self-perceived effects of dizziness on everyday life were not observed between concussed and nonconcussed, control athletes 6 months and 1 year following sport-related concussion.

87842 The Effects of Head Impact Exposure on Changes in Neurocognitive and Oculomotor Function Across a High School American Football Season: A Pilot Study

ABSTRACT IMPACT: This work reveals the influence of a season of American football-related head impact exposure on two functional outcome measures in a cohort of adolescent boys, shedding light on the chronic effects of 'subconcussive head impacts.' OBJECTIVES/GOALS: To examine the influence of a season of exposure to head impacts in American football on changes in neurocognitive and oculomotor function in adolescent male athletes. METHODS/STUDY POPULATION: Participants were recruited from a local high school: the football group (FB; n = 26) was instrumented with sensor-installed mouthguards to track impact exposure during games and practices, and members of the men’s cross-country team were recruited to the control group (CON; n = 9). All participants were administered Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) and were assessed for near point of convergence (NPC) at pre- and post-season. Linear models will be fit for changes in the five ImPACT composite scores and NPC values, with group and one of the head impact variables as predictors for each model. In a secondary within-group analysis, correlation coefficients will be calculated for the relationships between the head impact variables and the functional change scores for the FB group. RESULTS/ANTICIPATED RESULTS: The two groups did not differ significantly on age or number of previous concussions; the CON group had significantly lower BMI. Group assignment was significantly associated with change in NPC (p < 0.05 for all three models); no significant associations were observed for any of the head impact variables with change in NPC. Group and each of the head impact variables (total impacts, sum of peak linear acceleration [PLA], and sum of peak rotational acceleration [PRA]) were not significantly associated with change in any of the five ImPACT composite scores. Change in visual memory composite score was negatively correlated with total impacts (r = -0.37, p = 0.034) and sum of PRA (r = -0.36, p = 0.040). DISCUSSION/SIGNIFICANCE OF FINDINGS: Significant, albeit relatively weak, correlations between change in visual memory composite score and two head impact kinematic variables, coupled with significant increases in NPC in the FB group compared to the CON group, suggest that a season of exposure to football-related head impacts has the potential to elicit minor functional impairments.

Predictor factors of prism effectiveness in young adults with convergence insufficiency

ABSTRACT Clinical relevance: The findings of this study can be useful in the process of patient selection as well as in optimising the prescription of the prism in patients with convergence insufficiency. Background: To determine the relationship between the demographic variables and baseline clinical characteristics with the prism effectiveness in young adults with convergence insufficiency. Methods: Sixty-four young adults with convergence insufficiency entered a randomised clinical trial and were randomly assigned to either treatment or placebo groups. For participants in the treatment group, the near optical correction containing base-in prism was determined based on the Sheard’s criterion. Participants in the placebo group received near optical correction. After three months of using the assigned correction, the outcome examinations were performed. Results: In the univariate analysis, a remote near point of convergence, a higher baseline symptoms score, and a higher prescribed prism power showed a significant relationship with the increase in prism effectiveness. A significant inverse relationship was found between the near positive fusional vergence, vergence facility, and prism adaptation rate with the prism effectiveness. Based on the results of the multiple regression, the prism adaptation rate was the only independent predictor factor of prism effectiveness, so that the prism effectiveness increased by 0.60 for each per cent reduction in prism adaptation rate. Conclusion: Prism adaptation is the only independent predictive factor of prism effectiveness in young adults with convergence insufficiency. Based on the findings of the present study, it is recommended that careful assessment of prism adaptation be considered before considering prism prescription.

The distribution of the near point of convergence and its related factors in an elderly population: the Tehran Geriatric Eye Study (TGES).

To determine the distribution of the near point of convergence (NPC) and its related factors in an elderly population in Tehran, Iran. This population-based cross-sectional study was conducted on the elderly population (60 years of age and over) of Tehran, Iran in 2019. The samples were selected using stratified random cluster sampling. The examinations included the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternate cover test, ocular health examination, and NPC measurement. The mean age of the participants was 65.90 ± 4.56 years and 59.6% of them were females. The mean (95% CI) NPC in the total sample was 7.84 cm (95% CI: 7.65-8.03). The mean (95% CI) NPC in males and females was 7.92 cm (7.63-8.21) and 7.75 cm (7.54-7.97) (P = 0.338), respectively. The mean NPC increased from 7.8 cm (95% CI: 7.55-8.05) in the age group 60-64 years to 8.83 cm (95% CI: 7.47-10.2) in the age group ≥ 80 years (P > 0.05). The mean (95% CI) NPC in emmetropic, myopic, and hyperopic individuals was 7.67 cm (95% CI: 7.33-8.02), 7.96 cm (7.56-8.37), and 7.87 cm (7.63-8.11), respectively (P = 0.378). There was no statistically significant relationship between NPC with education level, smoking, diabetes mellitus (DM), and hypertension (HT). The NPC values found in this study were significantly lower (less remote) than the values reported in previous studies in similar age groups. The NPC had no significant relationship with age, sex, education level, smoking, DM, and HT.

Determining Near Point of Convergence: Exploring a Component of the Vestibular/Ocular Motor Screen Comparing Varied Target Sizes

BackgroundNear point of convergence (NPC), a component of the Vestibular Ocular Motor Screening (VOMS) assessment, may be helpful in diagnosing concussion. The VOMS uses a standardized approach to measure NPC; however, methods of screening for NPC are not standardized.PurposeThe purpose of this study was to determine whether four different methods of measuring NPC yielded different estimates.Study DesignDescriptive within-subjects laboratory study.Level of EvidenceLevel 3.MethodsHealthy recreational athletes participated in a comparison of 4 commonly used methods of measuring NPC: a 12-point font target, the VOMS (14-point font target), the tip of a black pen, and the Bernell VergelTM device (9-point font target). The order of the presentation of the 4 targets was randomized.ResultsSeventy-five participants (59 females, 16 males; mean [SD] age=21.0 [6.12] years) completed 3 trials. The mean (SD) of the 900 NPC measurements was 7.11 (3.67) cm. Measurements for all targets had excellent reliability (r=0.94 to 0.98). In a comparative analysis, participant age was associated with NPC (p<0.01) and was covaried. The NPCs derived from both the 12-point and 14-point font targets were smaller than NPCs from the tip of the black pen and the 9-point font device (p<0.01). Measurements between the tip of the black pen and the 9-point font device (p=0.25) and between the 12-point and 14-point font targets (p=0.84) did not differ.ConclusionsThe method used to measure NPC as a screening test for concussion should be standardized because the estimate differs depending on the technique chosen. The current study supports previous findings that the type of target used to measure NPC should be standardized for concussion assessment.Clinical RelevanceScreening of NPC should be standardized for concussion assessment to improve the reliability of NPC testing.

Binocular Vision in Patients with Multiple Sclerosis.

PurposeOculomotor disorders have been reported in multiple sclerosis (MS) in up to 80% of cases. There have been studies evaluating binocular vision in several neurological diseases, but not in MS. Considering that a high percentage of eye-movement anomalies have been reported, the aim of this study was to analyze binocular vision in these subjects.MethodsA total of 59 participants with MS — 21 with monocular optic neuritis, eleven with binocular optic neuritis, and 27 without optic neuritis — and 26 age-matched controls were enrolled. Binocular vision was analyzed using near point of convergence (NPC), positive and negative fusional vergence for far and near distance, measurement of heterophoria at both distances with cover and modified Thorington tests, and random-dot stereoscopy.ResultsThe percentage of subjects with abnormal NPC values was highest in the MS group, followed by the MSONm (MS with optic neuritis in one eye), MSONb (MS with optic neuritis in both eyes), and control groups. MS patients showed an esophoric trend at near distance. Positive fusional vergence showed no significant differences between control and MS groups, but higher variability in recovery was found in MS groups. Negative fusional vergence at near distance showed significant differences between the control group and the two MS groups, with optic neuritis for both break-point and recovery values. A high percentage of patients with MS had alterations on stereopsis.ConclusionAlterations in binocular vision were present in MS, with divergence at near distance and stereopsis the most affected parameters. Likewise, MS patients with optic neuritis showed worse binocular vision.

Development and Validation of a Mobile Application to Detect Visual Dysfunction Following Mild Traumatic Brain Injury.

Following mild traumatic brain injury, visual dysfunction is a common occurrence, yet the condition often goes undiagnosed. A mobile application was developed to measure aspects of visual acuity and oculomotor function. The aim of this project was to validate the newly developed suite of outcomes conducive for use in the field to detect visual dysfunction. A custom mobile application was developed on an Apple iPad using iOS operating system software version 11.0 in Objective C to measure near point of convergence (NPC), distance visual acuity, reading fluency, and self-rated convergence insufficiency (CI). To determine construct validity, 50 healthy young adults were administered NPC and distance visual acuity assessments using the iPad and standard clinical approaches. A ruler measurement was obtained simultaneous to the iPad NPC measurement to determine measurement accuracy. All testing was administered by a licensed optometrist and the order of testing (iPad versus clinical) was randomized. The correlation coefficient between the iPad and clinical measurements of NPC was 0.893, while iPad and ruler measurement was 0.947. Modest accordance was found between iPad and wall chart measures assessing distance visual acuity. A ceiling effect was evident with use of a wall chart to determine distance visual acuity. Healthy young adults scored a mean (SD) of 13.0 (7.4) on the Convergence Insufficiency Symptom Survey. Reading fluency was highly variable with a mean (SD) of 291 (119) words per minute. iPad measures of NPC were highly correlated with clinical measures, while visual acuity measured with the iPad showed modest correlation. Nonetheless, the suite of visual assessments provide value as screening tools, and when used in combination with reading fluency assessment and self-reported CI may be effective in identifying visual dysfunction following mild traumatic brain injury.

A comparison of accommodation and ocular discomfort change according to display size of smart devices

BackgroundTo evaluate the change of accommodation and ocular discomfort according to the display size, using quantitative measurements of accommodation and ocular discomfort through subjective and objective metrics.MethodsForty six subjects without any ophthalmic disease history were asked to watch the documentary movie, using two different sizes of smart devices; smartphones and tablets. Before and after using devices, the near point accommodation (NPA) and the near point convergence (NPC) were measured, and objective accommodation was measured using an auto refractometer/keratometer. The subjective ocular discomfort was assessed through a survey.ResultsBoth devices showed a decrease in post-use NPA and NPC, and the change after use of the smartphone was significantly severe, 1.8 and 2.5 folds respectively, compared to tablet (p = 0.044, p = 0.033, respectively). Neither smartphone nor tablet showed significant changes in the accommodative response induced by dynamic accommodative stimulus of auto refractometer/keratometer (p = 0.240 and p = 0.199, respectively). Subjects showed a more severe increase in ocular discomfort after using smartphones (p = 0.035) and reported feeling tired even with shorter use times (p = 0.012).ConclusionsBoth devices showed significant decreases in NPA and NPC, and the larger changes were seen when using the small display smartphone. Even within 20minutes of using, subjects start to feel ocular discomfort, and it was more severe and faster after smartphones than tablets. Therefore, the smaller the display size, the greater the adverse impact on eyes, and thus, appropriate display size will need to be selected depending on the time and purpose of use.

The impact of high- and moderate-intensity exercise on near-point of convergence metrics

ABSTRACT Background: Near point of convergence (NPC) assesses the vergence ability of the visuo-oculomotor system; however, little is known regarding: the extent and duration exercise impacts NPC and the between- and within-day reliability of NPC metrics. Methods: An accommodative ruler with a miniature Snellen chart was placed upon the philtrum (upper lip). Participants (n=9) focused upon a ‘V’ sized 20/20, while the chart was moved at ~1–2 cm/s toward and away from the eyes (twice in each direction). Testing commenced at 8:00am with NPC measures being collected at baseline before three randomized conditions with serial follow-ups occurring at six post-condition timepoints (0–8 hours following). The conditions consisted of 25-minutes high-intensity intervals (10, one-minute intervals at ~85-90% heart-rate reserve), 45-minutes of moderate-intensity exercise (at ~50-60% heart-rate reserve), and a control condition (30-minutes quiet rest). Results: NPC was not impacted across any of the three conditions (all p > .59). Additionally, NPC measures between baseline conditions and across the control condition displayed very high levels of within-day and between-day reliability (coefficient of variation <3.8%). Conclusions: Future NPC measures using an accommodative ruler can be taken immediately following exercise and may be pertinent as a complementary tool in the future sideline screening of concussion.

Comparison of home-based pencil push-up therapy and office-based orthoptic therapy in symptomatic patients of convergence insufficiency: a randomized controlled trial.

To assess and compare the effectiveness of home-based pencil push-up therapy (PPT) and office-based orthoptic therapy (OBOT) in patients with convergence insufficiency. In this randomized clinical trial, 176 symptomatic patients with convergence insufficiency, aged between 9 to 30years, were randomly assigned to receive 6weeks of home-based PPT (Group I) or OBOT (Group II) after determining refractive error, near point of convergence (NPC), convergence insufficiency symptom survey (CISS) score, near phoria and positive fusional vergences (PFV) at near. The participants of Group I underwent home-based PPT (pencil push-ups exercises15 minutes per day, daily for 6weeks) and those of Group II OBOT (convergence fusional exercises on synoptophore for 20min per day, 3days a week, for 6weeks) without home reinforcement. Patients were re-examined at 3 and 6weeks after initiation of treatment. NPC and CISS score were the primary and secondary outcome measures, respectively. Statistical analysis was performed with the independent samples t-test, Friedman test and the analysis of variance (ANOVA). Statistical significance was indicated by p-value < 0.05. Participants of both the groups had statistically significant improvement in NPC, CISS score, PFV and near phoria (p < 0.001), but there was no statistically significant difference between the two groups (p > 0.05). However, patients of Group II had significantly better PFV after final visit than those of Group I (p < 0.001). Home-based PPT with good suppression control and with compliance ensured by log book entries, is a simple, cheap, less time consuming and comparably effective alternative to more expensive OBOT for patients suffering from CI. CTRI registration number: REF/2016/11/012,732, Date of registration 25/04/ 2016, Retrospectively Registered.

Abobotulinum toxin A for periorbital facial rejuvenation: impact on ocular refractive parameters

ABSTRACT Clinical relevance Botulinum toxin is commonly used for cosmetic facial rejuvenation and can result in pain at the injected site, bruising and ecchymosis, erythema and oedema, headache, diplopia, blurred vision, focal facial weakness. This study evaluates the impact of botulinum toxin on refractive error and binocular vision. Background Botulinum toxin (trade name: Dysport) is a neurotoxic protein which is made from a Gram‐positive anaerobic bacterium known as Clostridium botulinum. In this study, we aimed to evaluate the impact of Dysport injection on refractive error, near point of accommodation and convergence, and palpebral fissure height. Methods Twenty‐eight subjects were treated for facial wrinkles, using Dysport. A 500‐unit vial of Dysport was diluted with 2.5-ml preserved normal saline, and injected doses were 30-units for crow’s feet, six units for lower eyelid wrinkles, 25 to 50-units for glabellar lines (five points), and 20 to 40 for forehead creases on four points. The refractive error, near point of accommodation and convergence and palpebral fissure heights were assessed before and two weeks after injection. Results The participants comprised 23 women and five men at a mean age of 53.51 ± 14.1-years. The means of the equivalent sphere before and after injection were −0.07 ± 1.34 and −0.08 ± 1.35 (p = 0.36). The means of near point of accommodation monocularly before and after injection were 29.75 ± 6.16-cm and 26.75 ± 6.00, respectively. The means of near point of convergence before and after injection were 16.03 ± 5.27-cm and 15.55 ± 6.14, respectively (p = 0.30). The means of palpebral fissure height before and after injection were 10.33 ± 1.69-mm and 10.20 ± 1.46-mm, respectively. The changes in equivalent spherical refractive error, binocular near point of accommodation and convergence were not statistically significant. Conclusion Dysport injection for the correction of upper face animation lines, if performed at the appropriate sites and the appropriate concentration, has no significant impact on refractive error, near point of accommodation and convergence, and palpebral fissure height.

Nearwork-induced transient myopia and accommodation function before and after laser-assisted in situ keratomileusis surgery.

Purpose:To assess the change in Near Induced Transient Myopia (NITM) and other accommodation parameters, before and after undergoing LASIK surgery for myopia correction.Methods:Twenty-nine myopic subjects were recruited from a tertiary eye hospital in India. Age range was 21 to 35 years with an average age of 26.1 ± 3.5 years. Mean spherical equivalent was –3.86 D ± 1.50 D presurgery. NITM, lag of accommodation, near point of convergence (NPC), accommodative amplitude (AA), and binocular near accommodative facility (AF) were measured. All data were collected 21 days prior to and 30 days after LASIK surgery.Results:NITM, lag of accommodation and amplitude of accommodation were significantly lower (NITM -0.05 ± 0.15, Lag 0.38 ± 0.38, AA 10.27 ± 2.24) after surgery when compared to before (NITM 0.26 ± 0.12, Lag 0.77 ± 0.51, AA 12.18 ± 2.02; P < 0.001). Accommodative facility increased and near point of convergence was significantly more distal following surgery (AF 10.70 ± 2.29, NPC 7.96 ± 1.63) when compared to prior (AF 8.65 ± 2.74, NPC 5.62 ± 1.71; P < 0.001).Conclusion:Significant changes in NITM and accommodation function should be expected in the short term following LASIK surgery. This study supports the importance of evaluating accommodative parameters and patient counselling prior to and following refractive surgery.

Agreement between three methods for measuring near point of convergence among patients with different refractive errors.

PURPOSE:To describe the agreement of three methods of Near Point of Convergence (NPC) measurement among patients with different refractive errors.METHODS:60 asymptomatic subjects, 18 – 25 yrs old, were included in 3 groups: emmetropes, myopes and hypermetropes. All subjects underwent NPC break point and recovery point measurement by Royal Air Force (RAF) rule, Pencil Rule (PR) and penlight with red green glasses (RG) using standard techniques. The values obtained were compared within each group by Friedman test. Bland Altman plots were constructed and Limits of Agreement calculated.RESULTS:Hypermetropes performed poorly in RG test with significantly receded break point and recovery point values (10.30 ± 1.45cm, 13.13± 1.20cm) compared to RAF test (7.18 ± 1.86 cm, 10.15 ± 2.11cm ) and PR test (7.78 ± 1.75 cm, 10.75 ± 1.44cm). The recovery point values of the emmetropes with RG test (10.15 ± 2.32cm) was significantly receded compared to PR (9.30 ± 1.72 cm) and RAF test (Emm: 9.08 ± 2.30cm). The myopes performed better with PR test with significantly better recovery point values with PR test (8.70 ± 1.97 cm) compared to RAF (9.68 ± 2.08) and RG (9.45 ± 1.73) tests. The limits of agreement were wide suggesting disagreement between the tests.CONCLUSION:The RG test yields more receded results in hypermetropes compared to the RAF and PR tests, and the PR test yields better results than the RAF test in myopes. Thus, the results obtained by these different methods show a lack of agreement. The variability is not uniform in patients with different refractive errors.

New Progress in the Study of Convergence Insufficiency

Convergency insufficiency is typical symptoms such as blurring of distant vision, reexamination of near vision, jumping words and walking while reading, visual fatigue and so on after reading or working closely for a period of time, According to the corresponding symptoms and signs, visual function tests were carried out, such as far and near eye position, accommodative response (BCC), positive relative accommodation (PRA), negative relative accommodation (NRA), near point of convergence (NPC), accommodation amplitude (AMP), etc., The detected visual function data were evaluated according to the normal value of Morgan and Sherad criteria. In daily life, people not only require clear vision, but also pay great attention to the comfort of using eyes, and the convergency insufficiency has become one of the important factors hindering the clarity, persistence and comfort of vision. Making binocular vision system to produce the cognition of regulation, convergence and eye movement through various methods such as optics, psychology and physics, vision therapy improves the application ability of eye vision system, and finally cures visual function problems such as visual fatigue, adjustment and convergence abnormality. We review the incidence, pathogenesis, new progress in the treatment of convergence insufficiency, the mechanism of visual formation and the basic principles of visual training.