Mean Near Point Of Convergence Research Articles

Are binocular alignment and convergence amplitude different between phakic and pseudophakic older patients?

ABSTRACT Purpose To compare the binocular alignment status and convergence amplitude between phakic and pseudophakic older adults. Methods The present report is a part of the Tehran Geriatric Eye Study (TGES), a population-based study performed on the elderly population above 60 years of age in Tehran, Iran. All study participants were transferred to the examination site and underwent complete ocular examinations including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternating cover tests, and slit-lamp biomicroscopy. Results Of 3791 invitees, 3310 participated in the TGES (response rate: 87.3%). After applying the exclusion criteria, the data of 1969 individuals were analyzed for this report. The mean of far exophoria, far esophoria, near exophoria, and near esophoria was 5.09 ± 3.66, 8.20 ± 9.60, 6.94 ± 3.69, 7.00 ± 5.83 prism diopter in phakic and 5.15 ± 2.43, 6.50 ± 5.80, 7.77 ± 4.00, 4.75 ± 1.50 prism diopter in pseudophakic individuals, respectively. The mean of far exotropia, far esotropia, near exotropia, and near esotropia was 14.92 ± 9.49, 22.00 ± 13.86, 15.09 ± 7.20, 21.33 ± 14.47 prism diopter in phakic and 19.67 ± 22.5, 8.00 ± 0, 17.36 ± 7.55, 17.36 ± 7.55, 0 prism diopter in pseudophakic individuals, respectively. Near exophoria (P = .003) was significantly higher in pseudophakic than in phakic participants after controlling the effects of age, sex, body mass index, diabetes, and hypertension. The mean near point of convergence was 7.94 ± 3.27 cm in phakic and 7.99 ± 3.3 cm in pseudophakic participants. Conclusion Near exophoria was significantly higher in pseudophakic compared to phakic individuals while other deviations and near point of convergence were not significantly different between phakic and pseudophakic groups.

Disparity vergence differences between typically occurring and concussion-related convergence insufficiency pediatric patients

This study sought to test the hypothesis that significant differences would be observed in clinical measures, symptoms, and objective assessments of vergence eye movements between children with typically developing convergence insufficiency (TYP-CI) and children with persistent post-concussion symptoms with convergence insufficiency (PPCS-CI). Data from age-matched binocularly normal controls (BNC) were used for comparison. Data from three groups of children 11 to 17 years of age are presented: BNC (N = 11), TYP-CI (N = 10), and PPCS-CI (N = 15). Clinical measures of vergence, accommodation, and symptom severity were collected. Symmetrical 4° disparity vergence eye movements were quantified with an eye tracker integrated into a head-mounted display (Oculus DK2). Peak velocity and final response amplitude of convergence and divergence eye movement responses were assessed. The mean near point of convergence (break) was more receded (worse), the amplitude of accommodation more deficient, and convergent and divergent peak velocities slower in the PPCS-CI group compared with the TYP-CI and BNC groups. These results suggest that PPCS-CI may be a different clinical entity than TYP-CI. Hence, more research is warranted to determine whether the therapeutic interventions that are effective for TYP-CI can also be used for PPCS-CI populations.

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.

Convergence Insufficiency Neuro-mechanism in Adult Population Study Randomized Clinical Trial: Clinical Outcome Results

These data confirm the effectiveness of office-based vergence/accommodative therapy for improving the near point of convergence and positive fusional vergence in young adults with symptomatic convergence insufficiency within a double-masked longitudinal randomized clinical trial. This study aimed to report changes in clinical signs and symptoms of convergence insufficiency from a randomized clinical trial evaluating the effectiveness of office-based vergence/accommodative therapy for young adults with symptomatic convergence insufficiency. In this double-masked, randomized clinical trial, convergence insufficiency patients (n = 50; average age, 21 ± 3 years; range, 18 to 32 years) were randomized to either office-based vergence/accommodative therapy or office-based placebo therapy. Improvements in (1) near point of convergence, (2) positive fusional vergence, and (3) self-reported symptoms (Convergence Insufficiency Symptom Survey [CISS] score) were evaluated after twelve 1-hour sessions of treatment within the office comparing the results from the vergence/accommodative therapy and the placebo therapy groups. The mean near point of convergence improved by 6.0 and 3.1 cm in the vergence/accommodative and placebo therapy groups, respectively (mean difference of -2.9 cm; 95% confidence interval [CI], -4.6 to -1.0 cm; P < .01). The mean positive fusional vergence increased by 17.3 and 7.4Δ in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 9.9Δ; 95% CI, 4.9 to 16.0Δ; P < .001). The mean CISS score improved by 12.4 and 10.1 points in the vergence/accommodative and placebo therapy groups, respectively (mean difference of 2.3 points; 95% CI, -8.3 to +4.6 points; P = .56). Our results demonstrate that office-based vergence/accommodative therapy is effective for improving the near point of convergence and positive fusional vergence in young adults with symptomatic convergence insufficiency. However, given that both treatment groups had a similar reduction in self-reported symptoms, we recommend that the CISS be revised if it is to be used as an outcome measure in future studies of convergence insufficiency.

Socioeconomic Status and Race as Social Determinants of Health to be Considered in Clinical Use of Pre-Season Vestibular and Oculomotor Tests for Concussion

Aside from racial and socioeconomic disparities in computerized neurocognitive testing and symptomology, there is a scarcity of research representing more diverse populations on other widely used tests for concussion, including vestibular and visual assessment. The aim of the study was to investigate if racial and socioeconomic differences exist on baseline vestibular/ocular motor screening (VOMS) and King-Devick (K-D) test performance in high school student-athletes. A total of 670 participants (66.1% White, 33.9% Black) with a mean age of 15.43±1.2 years were administered a baseline VOMS, average Near Point of Convergence (NPC) distance, and K-D test. The exposure variables included race (White or Black) and socioeconomic status (SES), defined as free and reduced lunch status (FRL or No-FRL). FRL status was determined by each participant's school SES. The outcome variables consisted of baseline VOMS item symptom provocation scores, average NPC distance, and K-D baseline time. A series of Mann-Whitney U tests were performed for K-D baseline time, NPC distance, and VOMS items with FRL status or race as a between-subject factor. Two multivariable linear regressions were run to assess the association of (1) K-D baseline times using FRL, race, sex, and corrected vision as variables in the model and (2) average NPC distance using FRL, race, sex, and corrected vision as variables in the model. When adjusting for multiple comparisons, FRL athletes had slower (worse) K-D times (P<0.001) than non-FRL athletes. Black athletes had significantly lower mean NPC distance compared to White athletes at baseline (P=0.02) and FRL status athletes reported a significantly greater (worse) mean symptom provocation following the visual motion sensitivity item on the VOMS (P=0.02); however, these findings were no longer significant following adjustments for multiple comparisons. No differences were noted for any remaining VOMS items. The first model explained 3.9% of the total variance of K-D baseline times, whereas the second model was not significant. Racial and SES differences existed on average NPC distance and the K-D test at baseline. Possible explanations for group differences may be neurobiological, anatomical, and/or disparity in nature. With a higher probability of undiagnosed and uncorrected vision impairment, vestibular dysfunction, and saccadic eye tracking deficits likely to be more apparent as a consequence of poverty or health inequities, it is important that healthcare providers, especially those that diagnose and treat concussions, understand that performance on the VOMS and K-D tests at baseline may be subject to sociodemographic factors of SES and race. To provide the most culturally competent care, clinicians should consider sociodemographic variables of race and SES as social determinants of health worthy of attention on objective and subjective measures of baseline concussion assessment.

High Prevalence of Asthenopia among a Population of University Students

Purpose To determine the prevalence of asthenopia and its associated factors in a sample of university students in Iran.MethodsIn this cross-sectional study, participants were selected using multistage cluster sampling. Presence of at least one of the 10 symptoms—foreign body sensation, diplopia, blurred vision, eye swelling, dry eye, eye pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and photophobia—was considered as asthenopia. Ocular examinations, including uncorrected/corrected visual acuity measurement, objective/subjective refraction, cover test, amplitude of accommodation (AA), and near point of convergence (NPC) were performed.ResultsOf the 1,462 students (mean age: 22.8 3.1 years), 73% were women. The age- and gender-standardized prevalence was 70.9% (95% confidence interval [CI]: 68.3–73.5), 39.8% (95% CI: 36.4–43.1), and 19.7% (95% CI: 16.0–23.3) based on the presence of at least one, two, and three symptoms, respectively. The prevalence was significantly higher in females (P = 0.048), hyperopic students (P 0.001), and astigmatic participants (P 0.001). The mean AA and NPC were 9.7 2.6 D and 10.2 4.2 D (P = 0.008) and 7.0 2.1 cm and 7.7 3.9 cm (P 0.001) in participants with and without asthenopia, respectively. Multiple regression model revealed age (28–29 years), astigmatism, and NPC as independent associated factors (odds ratios: 3.51, 1.61, and 0.91, respectively).ConclusionThis study shows relatively high prevalence of asthenopia in university students. Demographic factors and visual system disorders are important risk factors and timely correction of conditions may lead to decreased asthenopia.

Near Points of Convergence and Accommodation in a Population of University Students in Iran.

PurposeTo determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran.MethodsThe subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart).ResultsOf 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18–20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18–20 years olds to 11.44 cm in those over 30 years ( = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes ( = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula.ConclusionThe NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population.

The distribution of near point of convergence in an Iranian rural population: A population-based cross-sectional study

ObjectiveTo determine the distribution of near point of convergence (NPC) according to age, sex, and refractive error in a rural population above 1 year of age in 2015. MethodsIn this population-based cross-sectional study, multistage cluster sampling was applied to randomly select two underserved areas from the north and southwest of Iran and all individuals above 1 year living in these areas were invited to participate in the study. All participants underwent ocular examinations including visual acuity measurement, refraction, binocular vision testing including cover test and measurement of NPC, and slit lamp biomicroscopy. ResultsOf 3851 who were invited, 3314 participated in the study (response rate: 86.5%). The NPC was 8.42 ± 2.94 cm in the whole population, 8.59 ± 3.07 cm in men, and 8.30 ± 2.84 cm in women. Subjects above 70 years of age had the most remote NPC (mean: 10.44 ± 3.07 cm). The mean NPC was 7.79 ± 2.93, 8.83 ± 2.72, and 9.63 ± 2.70 cm in emmetropic, myopic, and hyperopic participants, respectively. According to the results of a multiple linear regression model, NPC had a positive correlation with age (b: 0.058, p < 0.001), male sex (b: 0.336, p: 0.005), and hyperopia (b: 0.044, p: 0.011). Among the evaluated variables, age had the greatest effect on NPC (Standardized coefficient: 0.402). ConclusionThe distribution of NPC in the Iranian population is different from other populations. Since NPC is influenced by age more than any other variable and presented normal values according to age in this study, the results can be used to interpret clinical measurements for diagnosis and treatment purposes.

Near Point of Convergence in Iranian Schoolchildren: Normative Values and Associated Factors

ABSTRACTPurpose: To determine the distribution of near point of convergence (NPC) and its related factors in 6 to 12-year-old children. Methods: In a cross-sectional study in 2015, the urban and rural children of Shahroud, north of Iran, were sampled. All rural schoolchildren were invited to the study, and in the urban area, we conducted random cluster sampling. Examinations included measurement of uncorrected and corrected visual acuity, manifest, subjective, and cycloplegic refraction. NPC and near point of accommodation (NPA) were measured with the best optical correction. Results: Of the 6624 sampled schoolchildren, 5620 participated in the study, and after applying the exclusion criteria, the final analysis was conducted on data from 5444 students; their mean age was 9.24 ± 1.71 years (6–12 years) and 53.6% (n = 2918) of them were male. Mean NPC was 8.08 cm [95% confidence interval (CI): 7.96–8.19]; 8.07 cm (95% CI: 7.92–8.22) in males and 8.08 cm (95% CI: 7.91–8.25) in females (p = 0.954). NPC significantly recessed with age (p < 0.001). Mean NPC in emmetropic, myopic, and hyperopic children were 8.13, 7.04, and 8.23 cm, respectively (p < 0.001). The multiple linear regression model revealed significant associations for NPC with age (coefficient = 0.10, 0.95% CI: 0.05–0.15, p < 0.001), spherical equivalent refraction (coefficient = 0.17, 95% CI: 0.10–0.24, p < 0.001), and NPA (coefficient = 0.83, 0.95% CI: 0.76–0.90, p < 0.001). Conclusion: Mean NPC in 6–12-year-old Iranian children was 8.08 cm, which is worse than values reported in previous studies. Mean NPC showed a slight recession with age. Myopic schoolchildren had the least remote and hyperopes had the most remote NPC values. More remote values of NPA were associated with receded NPC.

Baseline Visual Measures in High School Football Players With and Without Previous Concussion

Visual impairments are common following sport-related concussion and may negatively affect athlete performance and safety if unresolved. PURPOSE: To examine differences in baseline visual assessment measures in high school football players with and without previous concussion. A secondary purpose was to examine the correlations between these asessments. METHODS: High school varsity football players (n=64, n=24 with concussion history) from a single high school (mean age=15.6±1.3 years) were enrolled in the study. Participants completed the following assessments prior to the start of the competitive football season: 1) three near-point of convergence (NPC) trials, 2) vision and sensory performance testing via the Senaptec Sensory Station, and 3) a demographic questionnaire. The independent variable was previous concussion history (with vs. without). Primary outcomes were average NPC across three trials (measured in centimeters) and the Senaptec Sensory Station scores for: visual clarity, contrast sensitivity, depth perception, near-far quickness, perception span, multiple object tracking, and hand-reaction time. Independent samples t-tests were used to examine differences in visual assessments between those with and without previous concussion. Pearson correlations examined relationships between all Senaptec Sensory Station and mean NPC measures. Alpha level was set to P < 0.05 a priori. RESULTS: Over half (62.5%) of those who reported a concussion history indicated that their most recent concussion was within the last year. There was no significant effect of concussion history on any of the visual assessment measures. There was a significant, but clinically insignificant correlation between mean NPC and binocular visual clarity (r=0.26; P=0.03). No other significant correlations among the visual assessment measures were identified (P < 0.05). CONCLUSION: High school football athletes, regardless of concussion history, exhibit similar baseline clinical and performance visual measures. Our data suggest that NPC and binocular visual clarity, while statistically correlated are clinically independent of one another and both worthy of evaluation in assessing concussion.

Accommodation, Convergence, and Stereopsis in Dyslexic Schoolchildren.

BACKGROUND:Previous studies have shown a correlation between reading problems and binocular function, but few studies have assessed visual skills in dyslexic students, particularly in Iranian Farsi-language students. This study is aimed to determine some of the binocular functions of dyslexic children and compare it with a group of age, sex, and social class-matched control children.MATERIALS AND METHODS:We conducted a case–control study on 27 dyslexic children and 40 age, sex, and social class-matched control children (all between 7 and 13 years old) in grades one to six. This study was performed at three elementary schools in Tehran, Iran. Monocular and binocular near point of accommodation (NPA) were measured using the subjective push-up method, near point of convergence (NPC) was determined using the standard push-up technique, and stereoacuity was tested with the Titmus stereotypes in all of the children.RESULTS:Mean NPA of the right eye was 6.90 cm in dyslexic group and 5.98 cm in the control group (P = 0. 003). Mean NPA of the left eye in dyslexic children was 7.32 cm and in the control group was 6.23 cm (P = 0. 003). Mean binocular NPA was 6.66 cm in dyslexic and 6 cm in the control group (P = 0. 049). However, mean NPC (P = 0.33) and mean stereoacuity (P = 0.785) did not differ significantly between the dyslexic and control groups.CONCLUSION:Our findings showed a reduced monocular and binocular NPA in dyslexic children so that this function should be assessed by an optometric clinician in children with dyslexia.

The prevalence of asthenopia and its determinants in a population of university students

PurposeTo determine the prevalence of asthenopia and some of its determinants in a population of Iranian university studentsMethodsIn this cross‐sectional study, multi‐stage cluster sampling was applied in students of Kazerun's universities in south of Iran. After selecting the subjects, ophthalmic examinations and interview was conducted with each student. In line with previous studies, any person with at least one of the symptoms of eye pain, dry eyes, eye swelling, blurred vision, diplopia, foreign body sensation, photophobia, tearing and low visual acuity was considered to have asthenopia.ResultsOf 1462 selected subjects with a mean age of 22.8 ± 3.1 years, 73% of them were females. The prevalence of asthenopia was 71.2%, 40.6%, and 19.7% based on having 1, 2, and 3 symptoms, respectively. The prevalence of asthenopia was 73.3% in females and 65.5% in males (P = 0.004). The highest (81.5%) and lowest (58.4%) prevalence of asthenopia was seen in the age group 28–29 years and 30 years and above, respectively. The prevalence of asthenopia was higher in hyperopic subjects than myopic and emmetropic subjects (P &lt; 0.001). The prevalence of asthenopia was 77.7% in astigmatic and 79.2% in anisometropic participants. The mean amplitude of accommodation was 9.7 ± 2.6 D and 10.28 ± 4.3 D in asthenopic and healthy subjects, respectively (P = 0.008). The mean near point of convergence was 7.2 ± 2.8 cm and 7.7 ± 3.9 cm in asthenopic and healthy subjects, respectively (P0 &lt; 0.001).ConclusionsThe prevalence of asthenopia is markedly high in university students, may causes difficulty in reading and is important to address this condition in this age group.

The distribution of near point of convergence and its association with age, gender and refractive error: a population‐based study

PurposeThe aim was to determine the distribution of the near point of convergence (NPC) and its association with age, gender and refractive errors through a population‐based study.MethodsIn this cross‐sectional study, samples were randomly selected from the population of Mashhad city in the northeast of Iran through stratified cluster sampling. In each of the 120 randomly selected clusters, 10 households were systematically chosen. Examinations included visual acuity testing, refractive and binocular vision examination. NPC was measured using a 6/12 single target on a Gulden fixation stick. Positive and negative fusional vergences were measured by the step method at far and near fixation distances.ResultsOf the 4,453 invitees, 3,132 people participated (response rate of 70.4 per cent) and after applying the exclusion criteria, analysis was conducted on data from 2,433 individuals whose mean age was 31.2 ± 15.1 years (range: 10 to 86 years). Mean NPC was 8.59 ± 4.82 cm (range: 2 to 40 cm) in the total sample, 6.95 ± 3.87 cm in the 10–19 years age group and 13.06 ± 5.2 cm in those over 70 years. The relationships of NPC with the variables ages, gender and refractive errors (spherical equivalent) was assessed in a multiple linear regression model. Based on this model, older age (p < 0.001, coefficient = 0.106), male gender (p = 0.002, coefficient = 0.608) maintained a significant correlation with NPC, while the association with refractive error was no longer significant (p = 0.109, coefficient = 0.128) after adjusting for age and gender.ConclusionThis is the first population‐based study to examine the normal ranges of NPC and also the first to describe normal values in a presbyopic population. The results of this study indicate an age‐related change in NPC. These changes should be noted in the interpretation of tests for the diagnosis and treatment of problems with binocular vision.

Strabismus and Near Point of Convergence and Amblyopia in 4–6 Year-Old Children

ABSTRACTPurpose: To determine the prevalence of strabismus and amblyopia, and the distribution of the near point of convergence (NPC), in a population of children aged 4 to 6 years.Methods: In this cross-sectional study, preschoolers in Mashhad were sampled using a random multistage cluster sampling approach. Examinations were done after obtaining parental consent. All participants had measurements of uncorrected visual acuity, corrected visual acuity, and non-cycloplegic refraction, and they had near and far cover tests to determine tropia and phoria.Results: Of the 3765 selected children, 3701 participated in the study. The prevalence of tropia was 1.21% (95% confidence interval [CI]: 0.86–1.57). Near and near/far tropia was observed in 0.83% (95% CI: 0.53–1.12) and 0.39% (95% CI: 0.18–0.59), respectively. Tropia was significantly more prevalent in boys (P=0.005). The most common type of tropia was esotropia, 0.22% (95% CI: 0.07–0.37). Among participants, 63.92% (95% CI: 62.36–65.48) had phoria; prevalence of far, near, and near/far phoria was 0.22% (95% CI: 0.07–0.37), 60.47% (95% CI: 58.88–62.07), and 3.22% (95% CI: 2.65–3.8), respectively. Mean NPC was 5.1 cm (95% CI: 5.05–5.14). NPC increased by 0.08 cm per month of age (P=0.033) and was 0.10 cm higher in boys compared to girls (P=0.027). Based on NPC, 61.58% (95% CI: 59.99–63.17) were symptomatic. The prevalence of amblyopia was 0.41% (95% CI: 0.20–0.61). The type of amblyopia was anisometropic, strabismic, and isoametropic in 75%, 11.1%, and 8.5%, respectively.Conclusion: The prevalence of amblyopia in this study population was not high; however, the prevalence of tropia was average compared to previous studies in Iran. Describing NPC in a 4- to 6-year-old Iranian population for the first time, we found that NPC increased with age in this sample.

Treatment of symptomatic convergence insufficiency with home-based computerized vergence system therapy in children

To evaluate the efficacy of a home-based computer orthoptic program for symptomatic convergence insufficiency (CI) in children. The medical records of participants aged 5 to <18 years who were diagnosed with symptomatic CI and were treated with the Computerized Vergence System (CVS) program were retrospectively reviewed. All participants were prescribed 9 or 15 minutes of daily convergence exercises with the CVS program, 5 days per week, for the initial 6 weeks. Near point of convergence (NPC) and near convergence amplitude (NCA) were measured at baseline, 6 week, and final examinations. The presence or absence of diplopia and asthenopia with reading were recorded at baseline and final examinations. A total of 186 participants were included. At diagnosis, 72 participants (39%) reported diplopia and 182 (98%), reported asthenopia. At final examination, 172 participants (92%) were asymptomatic. Twelve participants (6%) subsequently received other treatment modalities. Mean NPC at baseline (5.9 cm) improved after 6 weeks of CVS therapy (3.3 cm) and at final examination (2.9 cm; P < 0.0005). Mean NCA at baseline (20.3(Δ)) improved after 6 weeks of CVS therapy (37.0(Δ)) and at the final examination (38.0(Δ); P < 0.0005). In this study, home-based CVS therapy reduced symptoms related to CI and improved the NPC and NCA of most children aged 5 to <18 years with symptomatic CI.

The relationship between binocular vision symptoms and near point of convergence

Aim and Background:Due to the relatively high prevalence of binocular vision anomalies, a regular examination including tests for assessment and determination of these anomalies is necessary. The aim of this study was to assess the relationship between near point of convergence (NPC) and near binocular vision symptoms and finding of an NPC cutoff point for symptoms in university students.Materials and Methods:In this cross-sectional study, 124 students of different majors of Zahedan University of Medical Sciences were randomly selected. If they met the inclusion criteria, they were divided into two groups (symptomatic and asymptomatic) according to the convergence insufficiency symptom survey questionnaire. For NPC measurement, a small isolated letter E of approximately 20/30 size on a metal rod was used. After data collection, data were analyzed in SPSS.17 software (SPSS for Windows, SPSS Inc., Chicago, IL) using descriptive and analytical statistics, including Mann–Whitney U test and receiver operating characteristic (ROC) curve.Results:The mean NPC findings in the symptomatic and asymptomatic groups were 11.7 ± 5.0 and 8.4 ± 3.4 cm, respectively, with a significant difference between the two groups (P < 0.001). The ROC curve suggests an NPC cutoff point of 9.5 cm for the presence of symptoms with the testing procedures used in this study.Conclusion:The determination of NPC is helpful in the differentiation of symptomatic from asymptomatic subjects.

Treatment of symptomatic convergence insufficiency with a home-based computer orthoptic exercise program

To determine the efficacy of a home-based computer orthoptic program to treat symptomatic convergence insufficiency. A retrospective review of consecutive patients with symptomatic convergence insufficiency treated with a home-based computer orthoptic program was performed. Symptomatic convergence insufficiency was defined as: near point of convergence (NPC) >6 cm, decreased positive fusional vergence, exophoria at near at least 4(Δ) greater than at far, and documented complaints of asthenopia, diplopia, or headaches with reading or near work. The Computer Orthoptics CVS program was used for this study. Before beginning the computer orthoptic program, patients with an NPC >50 cm were given 4 base-in prisms and push-up exercises (NPC exercises with an accommodative target) for 2 weeks. A total of 42 patients were included. Mean treatment duration was 12.6 weeks; mean follow-up, 8.5 months. Of the 42 patients, 35 were treated with the home-based computer orthoptic program and push-up exercises; the remaining 7 only used the computer orthoptic program. Because of a remote NPC, 5 patients were given base-in Fresnel prism before starting treatment. Baseline mean NPC was 24.2 cm; posttreatment mean NPC improved to 5.6 cm: 39 patients (92.8%) achieved an NPC of ≤6 cm (p < 0.001). Positive fusional vergence improved in 39 patients (92.8%). Fourteen patients reduced their near exophoria by ≥5(Δ). A total of 27 patients (64.2%) reported resolution of symptoms after treatment. In our study, home-based computer orthoptic exercises reduced symptoms and improved NPC and fusional amplitudes. The computer orthoptic program is an effective option for treating symptomatic convergence insufficiency.

A prospective study of different test targets for the near point of convergence

To determine whether different test targets including an accommodative target (AT), a transilluminator (TR), and a transilluminator with a red lens (RL), affect the near point of convergence (NPC) value; and to determine which test target is most sensitive to identify convergence insufficiency (CI) in young adults. Subjects were 36 optometry students from the Illinois College of Optometry, including 18 subjects with normal binocular vision (control group) and 18 subjects with CI. None of the subjects had accommodative insufficiency. The NPC break and recovery were measured by three methods: AT, TR, and RL. Each test method was administered by a different examiner and the test sequence was randomized. The mean NPC break values for AT, TR, and RL in the control group were 4.31, 3.76, and 4.08 cm respectively, compared to 10.05, 11.37 and 13.04 cm in the CI group. The mean recovery values were 6.23, 5.56, and 5.95 cm for AT, TR, and RL respectively in the control group, vs 12.21, 14.37, 16.40 cm in the CI group. Significant differences in NPC break and recovery values were detected in the CI group between RL and AT, but not between AT and TR, or TR and RL. There was no significant difference in NPC values using the three targets in the control group. For an NPC cut point of 6 cm (break) and 9 cm (recovery), RL had higher sensitivity (100%) and specificity (88.9%) as well as lower false positive (10%) and false negative (0%) values compared to AT. NPC with RL is a more sensitive method to identify abnormal findings and assist in diagnosing CI compared to using AT or TR. We recommend that NPC with RL be routinely used to evaluate patients suspected of having CI.

Binocular function in school children with reading difficulties

Prior findings suggest that poor readers tend to have poor binocular vision skills, but data on the binocular abilities of children with poor reading skills are lacking. Our aim was to characterize distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, accommodative convergence/accommodation (AC/A) ratio, near point of convergence, and stereopsis in poor-reading school-age children without dyslexia selected from a non-clinical population. We conducted a cross-sectional study on 87 poor readers and 32 control children (all 8-13 years of age) in grades three to six recruited from eleven elementary schools in Madrid, Spain. With best spectacle correction in each subject, distance and near horizontal heterophoria measurements were obtained using the von Graefe technique, distance and near horizontal fusional vergence ranges were obtained using Risley rotary prisms, the AC/A ratio was measured using the gradient method, near point of convergence (NPC) was evaluated by the standard push-up technique using a transilluminator, and stereoacuity was tested with the Randot stereotest. Mean distance base-in break and base-in recovery values were nearly 2 Delta lower (p < 0.01) in the poor readers than those recorded in the control group. However, mean distance base-out vergences (blur, break and recovery), mean distance and near horizontal heterophoria, mean near horizontal fusional vergence ranges, mean AC/A ratio, mean near point of convergence (NPC), and mean stereoacuity did not differ significantly between the poor readers and controls. This study provides information on the binocular ability of children with poor reading skills but without dyslexia. Our findings suggest reduced distance base-in break and base-in recovery, such that distance fusional vergence ranges should always be assessed in children who complain of reading difficulties.

Are Orthoptic Exercises an Effective Treatment for Convergence and Fusion Deficiencies?

Purpose: To investigate whether orthoptic exercises are an effective way to influence the near point of convergence, fusion range and asthenopic symptoms. Methods: Seventy-eight patients met the inclusion criteria of visual acuity 6/9 or better, no history of orthoptic treatment, squint surgery or Meares Irlen syndrome/dyslexia. Information was collected from case records related to diagnosis, near point of convergence, fusion range, prism and cover test measurements and symptoms. Type, duration and frequency of exercises were also recorded. Non-parametric statistics were applied. Results: Patients ranged in age from 5 to 73 years (mean 11.9). Females outnumbered males (46:32). The diagnoses were: decompensating heterophoria (n = 50) or convergence insufficiency (n = 28: primary 27; secondary 1). Exophoria was more common (n = 65), than esophoria (n = 11) or orthophoria (n = 1). Treatments were aimed at improving near point of convergence and/or reduced fusional reserves. The mean treatment period was 8.2months. Reduced near point of convergence normalized following treatment in 47/55 cases, and mean near point of convergence improved from 16.6 to 8.4 cm (p = 0.0001). Fusional reserves normalized in 29/50. Fusional convergence improved significantly for those with exodeviation (p > 0.0006). Asthenopic symptoms improved in 65 patients. A reduction in deviation of 5 pd or more occurred in 20 patients. Conclusions: Orthoptic exercises are an effective means of reducing symptoms in patients with convergence insufficiency and decompensating exophoria, and appear to target the proximal and fusional components of convergence. Their role in esophoria is unclear and needs further study.