Lower tear meniscus height measured by optical coherence tomography in children.

INTRODUCTION: While optical coherence tomography (OCT) measurements of the lower tear meniscus height (LTMH) have been reported in adults, here we obtained LTMH measurements through Fourier Domain OCT in healthy children and compared these with values obtained in healthy adults. METHODS: Participants were children 7-17 years of age and a control group of adults 20-40 years of age. Inclusion criteria were no abnormal eye conditions or the use of contact lenses. Candidates who fulfilled the TFOS DEWS II criteria for dry eye disease (DED) were excluded. All subjects underwent LTMH measurement (OCT Spectralis) and tests for non-invasive tear break-up time and ocular surface staining. Participants also completed the ocular surface disease index questionnaire. RESULTS: A total of 86 children and 27 adults were included. Mean LTMH values in the children and adult groups were 217.40 ± 71.40 µm and 225.0 ± 54.86 µm, respectively; p = 0.53. However, 59.3% of the children had an LTMH ≤210 µm suggestive of DED, compared with only 33.3% of adults (p = 0.02). For the children, no significant differences in LTMH were observed with sex or for those more or less than 12 years of age. CONCLUSIONS: Optical coherence tomography-derived LTMH measurements were obtained in healthy children. While values were similar in children and adults, a greater proportion of children had an LTMH compatible with a diagnosis of DED. More studies in different paediatric populations are required to establish a complete set of normative LTMH measurements.

Prevalence of convergence insufficiency among Spanish school children aged 6 to 14 years

Clinical relevanceConvergence insufficiency (CI) at an early age can lead to learning difficulties affecting school performance. The aim of this study was to examine the prevalence of CI in a non-clinical population of Spanish children using well defined clinical criteria and to determine whether sex is a risk factor.MethodsVisual acuity and binocular vision tests were performed in 628 children aged 6–14 years (mean age 9.6 ± 1.3 years) at three schools in the Madrid Community, Spain. To assess CI prevalence we used CITT (Convergence Insufficiency Treatment Trial) criteria. The three signs considered were: i) exophoria at least 4∆ greater at near than at far; ii) near break point of convergence (NPC) ≥ 6 cm; and iii) reduced positive fusional vergence (PFV) at near (≤ 15∆ base-out break or failed Sheard's criterion).ResultsThe CI prevalence detected was 5.30% (33 children). Proportions of children with one or two signs of CI were 23.76% (148 children) and 12.20% (76 children), respectively. No differences in these CI rates by sex were detected.ConclusionThe clinically significant CI prevalence observed here suggests the need for more binocular vision screening programmes in school settings. (AU)

Measures of accommodative function in secondary school year 9 and year 13: a 4-year longitudinal study.

PURPOSE: To characterize accommodative function in secondary school children in year 9 and year 13 and assess the possible relationship between daily working conditions (number of near work hours and distances) and accommodation variables related to accommodative excess. METHODS: This was a prospective study. Participants were 43 subjects who were first examined in year 9 and then again when they were in year 13. The accommodation variables measured in each session were as follows: accommodation amplitude (AA), accommodative response (AR), monocular and binocular accommodation flexibility (MAF and BAF), negative relative accommodation (NRA), and positive relative accommodation (PRA). Other data recorded were the number of hours spent working at near vision tasks and the distances used for these tasks. Participants were classified as those with accommodation variables within the normal range (NA) and those with variables suggesting accommodative excess (AE). RESULTS: Several accommodative function variables were below normative values in both year 9 and year 13. The number of subjects classified as having AE went from 27.9% in year 9 to 58.1% in year 13 according to AR (p < 0.005) and from 23.3 to 46.5% according to MAF (p = 0.024). More near work was reported in year 13 (44.6 h/week) than year 9 (32.7 h/week) (p < 0.001). It emerged that subjects in year 13 spent more hours working at near if they had AE than if they were assigned to the NA group. No differences were detected in near work distances used by subjects in the NA and AE groups in both years. CONCLUSIONS: In both school years, values outside the norm were detected in several accommodative function measures. Also, devoting more hours to near work was linked to a greater extent of accommodative excess. We would therefore recommend regular accommodative function assessment in secondary school children.

Macular Thickness and Mesopic Visual Acuity in Healthy Older Subjects.

Purpose/Aim: Impaired mesopic visual acuity (VA) is a risk factor for incident early age-related macular degeneration (AMD) This study examines relationships between macular thickness measurements and photopic or mesopic VA in healthy eyes. MATERIALS AND METHODS: In 38 young and 39 older healthy individuals, total, inner, and outer retinal layer (IRL and ORL) thicknesses were measured in the macula region through spectral-domain optical coherence tomography (SD-OCT). Measurements were made across three subfields centered at the fovea: central foveal, pericentral, and peripheral. Best-corrected distance high-contrast (HC) and low-contrast (LC) VA were measured using Bailey-Lovie logMAR letter charts under photopic and mesopic luminance conditions. In addition, the low luminance deficit in VA (LLD, difference between photopic and mesopic VA) was calculated. Relationships were examined through Spearman correlation in each age group and through multiple linear regressions across all eyes. RESULTS: No significant correlations were detected between photopic VA (HC-VA and LC-VA) and macular thickness measurements in each age group. In mesopic conditions, age and pupil size were independent predictors of HC-VA (p = 0.001) and age and pericentral ORL thickness predictors of LC-VA (p = 0.001). Central foveal thickness emerged as the unique independent predictor of LLD (HC-VA, p = 0.013 and LC-VA, p = 0.005). Only in the older age group, was central foveal thicknesses correlated with LLD (HC-VA, r = + 0.45; p = 0.004 and LC-VA, r = + 0.33, p = 0.038). CONCLUSIONS: Greater macular thicknesses were related to worse mesopic VA and low luminance deficit in healthy subjects.

Macular Inner Retinal Layer Thickness in Relation to Photopic and Mesopic Contrast Sensitivity in Healthy Young and Older Subjects.

Purpose: To examine relationships between the thicknesses of ganglion cell (GC)-related macular layers and central photopic or mesopic contrast sensitivity (CS) in healthy eyes. Methods: Measurements were made in 38 young and 38 older healthy individuals. Total, inner, and outer retinal layer (IRL) thicknesses were measured in the macula region through spectral-domain optical coherence tomography (SD-OCT) across three subfields, or rings, centered at the fovea: central foveal, pericentral, and peripheral. Ganglion cell complex and circumpapillary retinal nerve fiber layer thicknesses were also measured. Low-spatial-frequency CS for gratings presented at the central 10° visual field were measured through computerized psychophysical tests under photopic and mesopic conditions. Relationships were examined by uni- and multivariate regression analysis. Results: Peripheral IRL thickness emerged as the only independent predictor of photopic CS (P = 0.001) in the young group and of photopic (P = 0.026) and mesopic CS (P = 0.001) in the older group. The slopes of regression lines used to predict CS from peripheral IRL thickness were significantly different for pair-wise comparisons of both photopic CS and age group (P = 0.0001) and mesopic CS (P = 0.0001) and age group. These models explained 37% of the variability in photopic CS and 36% of the variability in mesopic CS. Conclusions: Macular IRL thinning likely due to GC loss was related to reduced photopic and mesopic CS in older healthy eyes. In contrast, in the young eyes, a thicker macular IRL, possibly indicating transient gliosis, was associated with reduced CS.

Effects of Light Scatter and Blur on Low-Contrast Vision and Disk Halo Size.

PURPOSE: To investigate the individual effects of forward light scatter (FLS) and refractive blur on low-contrast vision and the size of the disk halo produced in response to an external glare source. METHODS: Monocular disk halo radius, high- and low-contrast distance visual acuity (HCVA, LCVA), and contrast sensitivity (CS) were determined in 25 eyes of 25 healthy subjects under normal, FLS, and blur conditions. FLS was induced using the filter Black ProMist 2 to simulate an early cataract. Blur was induced using a +1.00 diopter lens to simulate an uncorrected refractive error. RESULTS: Similar significant mean increases in halo radius were observed for the FLS (0.32 ± 0.10 log arc min; P < .0001) and refractive blur (0.40 ± 0.18 log arc min; P < .0001). Under induced blur, 3 lines of HCVA (0.32 ± 0.15 logMAR; P < .0001) and 4 lines of LCVA (0.39 ± 0.16 logMAR; P < .0001) were lost. FLS had a minimal (but significant) effect on HCVA, but worsened mean LCVA by more than 1 line (0.13 ± 0.10 logMAR; P < .0001). Similar significant mean CS reductions of 0.17 ± 0.12 (P < .0001) and 0.14 ± 0.12 log units (P < .0001) were produced in response to FLS and refractive blur, respectively (approximately 1 triplet). CONCLUSIONS: Forward light scatter and refractive blur contributed to an increased size of the disk halo produced by a glare source in similar proportion. Although defocus blur has a substantial effect on LCVA, a loss of more than 1 line of LCVA after best refractive correction would be indicative of FLS.

Binocular function changes produced in response to overnight orthokeratology.

PURPOSE: To analyze the binocular function changes produced on subjects undergoing overnight orthokeratology (OK) treatment over short-term (3 months) and long-term (3 years) wear. METHODS: A prospective, longitudinal study on young adult subjects with low to moderate myopia was carried out. Binocular function was assessed by the following sequence of tests: Distance and near horizontal phoria (Von Graefe technique), distance and near horizontal vergence ranges (Risley rotary prisms), accommodative convergence/accommodation (AC/A) ratio (gradient method) and the near point of convergence (standard push-up technique). The short-term sample consisted of: 21 subjects in the control group, 26 in a corneal refractive therapy (CRT) treatment lenses group and 25 in a Seefree treatment lenses group. Those subjects were evaluated at baseline and at a 3-month follow-up visit. Twenty one subjects were old CRT wearers that attended a 3-year follow-up visit (long-term group). RESULTS: A statistically significant difference over the 3-month treatment was found for divergence at distance: the break point decreased 1.4 Δ (p = 0.0006) in the CRT group and the recovery point increased 1.2 Δ (p = 0.001) in the Seefree group. Also, the Seefree group had an exophoric trend of 2.3 Δ at near (p = 0.02) and a base-out break decrease of 2.3 Δ (p = 0.03). For the long-term group, only the base-out break point at distant vision showed a statistically significant difference of 4.9 Δ (p = 0.02). CONCLUSIONS: OK induces minimal changes in the binocular function for either short-term or long-term periods, apart from a near exophoric trend over the short-term period.

Capacity of straylight and disk halo size to diagnose cataract.

PURPOSE: To examine the capacity of straylight and disk halo size to diagnose cataract. SETTING: Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain. DESIGN: Prospective study. METHODS: Straylight, disk halo radius, and high-contrast corrected distance visual acuity (CDVA) measurements were compared between patients with age-related cataract and age-matched normal-sighted control subjects by calculating the area under the curve (AUC) receiver operating characteristic. RESULTS: Measurements were made in 53 eyes of 53 patients with a mean age of 67.94 years ± 7.11 (SD) and 31 eyes of 31 controls with a mean age 66.06 ± 5.43 years. Significantly worse (P < .001) mean straylight (1.38 ± 0.24 log[s]), mean disk halo radius (2.40 ± 0.18 log minutes of arc [arcmin]), and mean CDVA (0.17 ± 0.11 logMAR) were recorded in the cataract group than in the control group (1.17 ± 0.11 log[s], 2.10 ± 0.16 log arcmin, and 0.08 ± 0.08 logMAR). Significant differences in AUCs were observed for disk halo radius (0.89 ± 0.04) versus straylight (0.77 ± 0.05) (P = .03) and disk halo radius versus CDVA (0.72 ± 0.05) (P = .001). The comparison of disk halo radius versus the discriminant function with input from CDVA and straylight (0.80 ± 0.05) was at the limit of significance only (0.091 ± 0.05, P = .051). CONCLUSION: Although all 3 variables discriminated well between normal eyes and eyes with cataract, the disk halo radius showed the best diagnostic capacity. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Relationship between halo size and forward light scatter.

PURPOSE: To determine the relationship between the size of a halo induced by a glare source and forward scatter or visual acuity (VA) in healthy eyes. METHOD: Measurements were made in the right eyes of 51 healthy individuals of mean age 29.3 ± 7.5 years. Halo radius was measured using the Vision Monitor and low luminance (1 cd/m(2)) optotypes presented at a distance of 2.5 m. The visual angle subtended by the radius of the halo was calculated in minutes of arc (arc min). Forward scatter or, straylight, was measured using the compensation comparison technique. Best-corrected distance VA was measured using high contrast (HC) (96%) and low contrast (LC) (10%) Bailey-Lovie logMAR letter charts under photopic (85 cd/m(2)) and mesopic (0.15 cd/m(2)) luminance conditions. RESULTS: Mean halo radius was 202 ± 43 arc min (3.4 ± 0.7°) and mean retinal straylight was 0.95 ± 0.12 log units. Mean photopic distance HC-VA and LC-VA were -0.02 ± 0.06 and 0.12 ± 0.09 logMAR, respectively. Mean mesopic distance HC-VA and LC-VA were 0.35 ± 0.11 and 0.74 ± 0.11 logMAR, respectively. Forward stepwise regression analysis revealed that halo radius was significantly correlated with straylight (r=0.45) and mesopic LC-VA (r=0.48), but not with photopic HC-VA and/or LC-VA and mesopic HC-VA. CONCLUSIONS: In healthy eyes, the larger the halo size induced by a given glare source, the greater the forward-scatter (straylight) and worse the mesopic LC-VA. Halo size seems to be independent of photopic HC-VA or LC-VA and mesopic HC-VA.

Normal values for the size of a halo produced by a glare source.

PURPOSE: To determine the size of a halo in the visual field induced by bright light in healthy eyes of all ages using the Vision Monitor (MonCv3; Metrovision, Pérenchies, France) and to assess the repeatability of the method. METHODS: Measurements were made in the right eyes of 147 healthy subjects (mean age: 48.2 ± 16.2 years) who were classified into six age groups. Using the Vision Monitor, optotypes of low luminance were presented at a distance of 2.5 m. The visual angle subtended by the radius of the halo was calculated in minutes of arc (arc min). The repeatability of the method was determined in a subset of 37 subjects older than 50 years by calculating the Bland-Altman coefficient of repeatability. RESULTS: The mean radius of the halo was 111.6 ± 39.8 arc min. Halo radius started to increase significantly from the age of 50 to 59 years. The relationship between halo radius and age (r = 0.65; P < .0001) was described by fitting a power function to the data. Halo size was independent of gender. The coefficient of repeatability of the method was ±44 arc min. CONCLUSIONS: Halo size increases with age following a power model. The normal halo size values provided could help clinicians distinguish between normal or abnormal glare problems. The intersession repeatability observed for halo size measurement indicates this method could be useful for assessing visual impairment caused by glare.

Relationship between macular pigment and visual acuity in eyes with early age-related macular degeneration.

PURPOSE: Today the extent to which MP impacts visual function in early AMD remains unclear. This study examines the relationship between macular pigment optical density (MPOD) and high-contrast visual acuity (HC-VA) and low-contrast visual acuity (LC-VA) in eyes with early age-related macular degeneration (AMD). METHODS: Measurements were made in 22 subjects with early AMD and 27 healthy control subjects. Distance best-corrected VA was measured using HC (96%) and LC (10%) Bailey-Lovie logMAR letter charts under photopic luminance conditions. MPOD was determined at the fovea through apparent motion photometry using the cathode ray tube-based Metropsis psychophysical vision test (Cambridge Research Systems). RESULTS: No significant differences in foveal MPOD were detected between the control eyes (0.30 ± 0.24 log units) and eyes with early AMD (0.27 ± 0.15 log units). Neither were differences detected between the two groups in mean HC- and LC-VA. Foveal MPOD showed significant correlation with both photopic HC-VA (r = -0.47, p = 0.0008) and LC-VA (r = -0.46, p = 0.0008) such that as MPOD increased, photopic HC-VA and LC-VA improved (lower logMAR values). CONCLUSIONS: Low MP levels were related to worse visual function in both healthy eyes and eyes with early AMD. Our findings provide direction for future studies designed to improve retinal function through the use of oral supplements known to increase MP levels, especially in eyes with AMD and a low MPOD.

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties.

BACKGROUND: Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties. METHODS: A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3-6 (aged 9-11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n = 46) and a without-treatment group (n = 36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed. RESULTS: Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p = 0.01). CONCLUSION: No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.

Impaired mesopic visual acuity in eyes with early age-related macular degeneration.

PURPOSE: To determine photopic and mesopic distance high-contrast visual acuity (HC-VA) and low-contrast visual acuity (LC-VA) in eyes with early age-related macular degeneration (AMD). METHODS: Measurements were made in 22 subjects with early AMD and 28 healthy control subjects. Inclusion criteria included a photopic HC-VA of 20/25 or better. Distance VA was measured using HC (96%) and LC (10%) Bailey-Lovie logMAR letter charts under photopic (85 cd/m(2)) and mesopic (0.1-0.2 cd/m(2)) luminance conditions. RESULTS: Mean mesopic distance HC-VA and LC-VA were significantly worse (0.1 logMAR and 0.28 logMAR, respectively) in the early AMD group than in the control group. Under mesopic conditions, the mean difference between LC-VA and HC-VA was significantly greater in the early AMD (0.45 logMAR) than the control group (0.27 logMAR). Mean differences between mesopic versus photopic HC-VA and mesopic versus photopic LC-VA were significantly greater in the early AMD than the control group (0.13 and 0.32 logMAR of difference between the means, respectively). Sensitivity and specificity were significantly greater for mesopic LC-VA than for mesopic HC-VA (Receiver Operating Characteristics, area under the curve [AUC], 0.94 ± 0.030 and 0.76 ± 0.067, respectively). AUC values for photopic HC-VA and LC-VA were below 0.70. CONCLUSIONS: Visual acuity testing under low luminance conditions emerged as an optimal quantitative measure of retinal function in early AMD.

Binocular function in school children with reading difficulties.

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Relationship between oculomotor scanning determined by the DEM test and a contextual reading test in schoolchildren with reading difficulties.

BACKGROUND: The relationship between oculomotor scanning and reading in poor readers of primary school age is not well known. This study was designed to assess this relationship by determining mean Developmental Eye Movement (DEM) test times and reading speeds in a Spanish non-clinical population of children with poor reading skills but without dyslexia. METHODS: We conducted a cross-sectional study on 81 poor readers (8-11 years of age) in the third to fifth grades recruited from 11 elementary schools in Madrid, Spain. In each subject with best spectacle correction, oculomotor scanning was measured using the DEM test, and reading speed (words per minute) was assessed by a standardized Spanish contextual reading test. RESULTS: Mean horizontal DEM times were higher than normative values for children in the third, fourth and fifth grades, by 20 seconds, 12 seconds, and 3 seconds respectively. Mean reading speeds were 18 words per minute lower than the norm for the third and fourth grades respectively, and 30 words per minute lower than the norm for the fifth grade. Reading speeds were significantly related to horizontal DEM times (r = -0.53, p < 0.0001). Thus, children showing a longer, or worse, horizontal DEM time achieved lower reading speeds. CONCLUSIONS: Poor readers showed poor horizontal scanning as assessed by the DEM test that was related to a slow reading speed. This test should be used by optometric clinicians as a screening tool to help identify poor reading skills in school children at an early stage.

Accommodative function in school children with reading difficulties.

BACKGROUND: Prior findings suggest correlation between reading problems and accommodative function, but few studies have assessed accommodation in children with poor reading skills. Our aim was to characterize monocular accommodative amplitude, relative accommodation and binocular accommodative facility in a population of healthy, non-dyslexic primary school children with reading difficulties. METHODS: We conducted a cross-sectional study on 87 poor readers and 32 control children (all between 8 and 13 years of age) in grades three to six recruited from 11 elementary schools in Madrid, Spain. In each subject with best spectacle correction, negative relative accommodation (NRA) and positive relative accommodation (PRA) were measured using a phoropter, monocular accommodative amplitude (MAA) was determined using the minus lenses method, and binocular accommodative facility (BAF) was measured using the Bernell Acuity Suppression Slide (VO/9) and a +/- 2.00 D accommodative demand for a period of 1 minute. RESULTS: Monocular accommodative amplitude was significantly lower (p < 0.001) in the group of poor readers (right eye 9.1 D +/- 2.3, left eye 9.0 D +/- 2.3) than in the control group (right eye 10.5 D +/- 1.7, left eye 10.5 D +/- 1.7). Binocular accommodative facility values were significantly lower (p < 0.05) in the poor readers (4.9 cpm +/- 3.1) than controls (6.3 cpm +/- 2.9). Negative and positive relative accommodation values were similar in both groups of children. CONCLUSIONS: This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility, such that this function should be assessed by an optometric clinician in children whose reading level is below average.

Normal values of distance heterophoria and fusional vergence ranges and effects of age.

BACKGROUND: Although it is well known that age affects visual function, we still have much to learn about the impact of aging on binocular vision. Our aim was to establish distance heterophoria and distance fusional vergence ranges in a large non-clinical population of wide age range, to provide normal values for comparisons. METHODS: A cross-sectional study was performed on 271 non-clinical subjects stratified into six age groups. Distance heterophoria measurements were obtained using the von Graefe technique and distance horizontal fusional vergence ranges using Risley rotary prisms in each subject, with best spectacle correction. RESULTS: The mean heterophoria value for distance fixation was exophoric except for the 71-80 year age group, which was esophoric. No effects of age were observed on distance heterophoria and distance base-in and base-out break means. However, a significant effect of age was noted on base-in recovery and base-out recovery. Between the youngest and oldest age groups, mean base-in recovery decreased by 2.5 Delta and mean base-out recovery by 3.3 Delta. CONCLUSIONS: Distance base-in and base-out recovery means diminished significantly with age such that recovery values fell outside the norm in subjects in the 61-70 year age group and older. This study establishes statistical normal values for distance heterophoria and fusional vergence in a non-clinical population. Mean values such as these are valuable tools for identifying subjects with far binocular anomalies.