Comparison of preschool vision screening methods in a population with a high prevalence of astigmatism.

PURPOSE: To compare the effectiveness of four methods of screening 3- to 5-year-old children for astigmatism high enough to require spectacle correction. METHODS: Lea Symbols Visual Acuity Screening (LSVAS), MTI Photoscreening (MTIPS), Nidek KM-500 Keratometry Screening (KERS), and Retinomax K-Plus Noncycloplegic Autorefraction Screening (NCARS) were attempted on 379 preschool children who are members of a Native American tribe having a high prevalence of astigmatism that is primarily corneal in origin. The need for spectacle correction was determined by cycloplegic refraction. Receiver Operating Characteristic (ROC) curves were fit, confidence intervals were determined, and area under the curves was compared. RESULTS: Astigmatism > or = 1.00 D was present in the right eye of 47.5% and in the left eye of 48.0% of children. Spectacles were prescribed for children < 48 months of age who had cylinder > or = 2.00 D and children > or = 48 months who had cylinder > or = 1.50 D, with the result that 33% of subjects required spectacles. Area under the ROC curve was 0.98 for NCARS, 0.92 for KERS, 0.78 for MTIPS, and 0.70 for LSVAS, and each of these values differed significantly from the other three (all P < 0.007). Testability was significantly higher for NCARS (99.5%) and KERS (99.7%) than for MTIPS (93.5%) and LSVAS (92.0%). CONCLUSIONS: In a population that included many children with astigmatism, objective, fully automated screening methods (NCARS and KERS) were superior to both visual acuity screening and photoscreening with subjective interpretation in identifying children who had astigmatism requiring spectacle correction.

Interobserver agreement for grating acuity and letter acuity assessment in 1- to 5.5-year-olds with severe retinopathy of prematurity.

PURPOSE: To evaluate interobserver test-retest reliability of the Teller Acuity Card procedure for assessment of grating acuity at ages 1, 2, 3.5, 4.5, and 5.5 years, for HOTV letter acuity at 3.5 and 4.5 years, and for Early-Treatment Diabetic Retinopathy Study (ETDRS) letter acuity at 5.5 years in the multicenter study of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP). METHODS: Subjects were the 73 participants in the CRYO-ROP study who had acuity assessed at one or more ages by two of the seven study visual acuity testers as part of a quality control procedure. All subjects had birth weights of less than 1251 g, and all had severe (threshold) ROP in one or both eyes. RESULTS: For sighted eyes, interobserver agreement for grating acuity (across all five test ages) was 0.5 octave or better in 57% of eyes and 1.0 octave or better in 85% of eyes. Interobserver agreement for letter acuity (3.5-, 4.5-, and 5.5-year test ages) was 0.5 octave or better in 71% of eyes and 1.0 octave or better in 93% of eyes. For all eyes (sighted and blind), Kendall rank correlation coefficients (Tau) were 0.86, 0.83, and 0.94 for grating, HOTV, and ETDRS acuity, respectively. Kappa statistics on data from all eyes indicated excellent interobserver agreement for grating, HOTV, and ETDRS acuity (0.73, 0.80, and 0.84, respectively). Interobserver agreement was not related to age or to severity of retinal residua of ROP. CONCLUSIONS: Excellent interobserver agreement for grating acuity measurements and for letter acuity measurements was obtained. Results suggest that with careful training and implementation of quality control procedures, high reliability of visual acuity results is possible in clinical populations of young children.

Shape recognition contributions to figure-ground reversal: which route counts?

Observers viewed upright and inverted versions of figure-ground stimuli, in which Gestalt variables specified that the center was figure. In upright versions, the surround was high in denotivity, in that most viewers agreed it depicted the same shape; in inverted versions, the surround was low in denotivity. The surround was maintained as figure longer and was more likely to be obtained as figure when the stimuli were upright rather than inverted. In four experiments, these effects reflected inputs to figure-ground computations from orientation-specific shape representations only. To account for these findings, a nonratiomorphic mechanism is proposed that enables shape recognition processes before figure-ground relationships are determined.

Reproducibility of corneal astigmatism measurements with a hand held keratometer in preschool children.

AIMS: To evaluate the overall accuracy and reproducibility of the Alcon portable autokeratometer (PAK) measurements in infants and young children. METHODS: The accuracy of the Alcon PAK in measuring toric reference surfaces (1, 3, 5, and 7 D) under various suboptimal measurement conditions was assessed, and the reproducibility of PAK measurements of corneal astigmatism in newborn infants (n = 5), children (n = 19, age 3-5 years), and adults (n = 14) was evaluated. RESULTS: Measurements of toric reference surfaces indicated (a) no significant effect of distance (17-30 mm) on accuracy of measurements, (b) no systematic relation between amount of toricity and accuracy of measurements, (c) no systematic relation between angle of measurement and accuracy, (d) no difference in accuracy of measurements when the PAK is hand held in comparison with when it is mounted, (e) no difference in accuracy of measurements when axis of toricity is oriented obliquely than when it is oriented horizontally, with respect to the PAK, and (f) a small positive bias (+0.16 D) in measurement of spherical equivalent. The PAK did not prove useful for screening newborns. However, measurements were successfully obtained from 18/19 children and 14/14 adults. There was no significant difference in median measurement deviation (deviation of a subject's five measurements from his/her mean) between children (0.21 D) and adults (0.13 D). CONCLUSIONS: The PAK produces accurate measurements of surface curvature under a variety of suboptimal conditions. Variability of PAK measurements in preschool children is small enough to suggest that it would be useful for screening for corneal astigmatism in young children.

Reproducibility and accuracy of measurements with a hand held autorefractor in children.

AIM: To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic. METHODS: Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error. RESULTS: Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D. CONCLUSIONS: Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

Visual field extent in children 3.5-30 months of age tested with a double-arc LED perimeter.

Visual field extent along the four diagonal meridia was measured cross-sectionally in 180 normal children (infants and toddlers), and 22 adults. Infants were tested monocularly at 3.5, 7, or 9 months, and toddlers were tested binocularly at 11, 17, or 30 months. Adult control data were obtained under monocular viewing. Three testing methods were investigated: static and hybrid static-kinetic perimetry, using LED arrays under computer control, and kinetic perimetry, using white styrofoam spheres manipulated by hand. Data analysis included corrections for false positives in the method of constant stimuli and for errors of anticipation in the ascending method of limits. Across all data sets from children, kinetic perimetry yielded larger, more adult-like fields, which approached adult levels around 17 months, whereas static and hybrid static-kinetic perimetry yielded smaller visual fields, approaching adult levels only at 30 months.

Astigmatism and Amblyopia among Native American Children (AANAC): design and methods.

The overall goal of the AANAC study is to improve detection of astigmatism and prevention of amblyopia in populations with a high prevalence of astigmatism. To meet this goal, the study will evaluate four methods of screening for astigmatism in preschool children and will assess both the short-term and long-term benefits of early correction of astigmatism in improving acuity and preventing amblyopia. This paper presents an overview of the design and methodology of the AANAC study. Subjects are members of the Tohono O'Odham Nation, a Native American tribe with a high prevalence of astigmatism. Preschool-age children who attend Head Start are screened with four tools: the Marco Nidek KM-500 autokeratometer, the MTI photoscreener, the Nikon Retinomax K-Plus autorefractor, and the Lea Symbols acuity chart. Sensitivity and specificity for detection of significant astigmatism, as measured by a technique that uses both cycloplegic retinoscopy and cycloplegic autorefraction, is determined for each of the four screening tools. Presence of amblyopia is evaluated by measurement of best-corrected recognition acuity and acuity for orthogonal gratings. Spectacles are provided to all 3-year-old children with > or =2.00 diopters (D) of astigmatism and all 4- and 5-year-old children with > or =1.50 D of astigmatism. Persistence of amblyopia after glasses wearing is evaluated by follow-up measurement of best-corrected recognition acuity and acuity for orthogonal gratings, conducted 2-5 months after glasses are prescribed. Long-term effectiveness of early screening and glasses prescription is evaluated through measurement of recognition acuity in two groups of first-grade children: one group who participated in the Head Start program before the intensive vision screening program was initiated, and a second group who participated in the study's Head Start vision screening program.

Visual acuity screening versus noncycloplegic autorefraction screening for astigmatism in Native American preschool children.

INTRODUCTION: Visual acuity screening (VAS) is less reliable in preschoolers than in school-aged children as a means of detecting significant refractive error. We wished to compare the effectiveness of VAS with the effectiveness of an objective method, noncycloplegic autorefraction screening (NCARS), in detecting the presence of significant astigmatism warranting spectacle correction. METHODS: We examined 245 Native American Head Start registrants aged 3 to 5 years. We attempted to obtain uncorrected visual acuity using Lea Symbols logMAR Chart (Precision Vision Inc, Villa Park, Ill), noncycloplegic autorefraction using the Nikon Retinomax K-plus (Nikon Corp, Melville, NY), and cycloplegic refraction (CR) on each eye. The VAS failure criterion was either a 2-line acuity difference between eyes or acuity worse than 20/40 in either eye. The NCARS and CR failure criterion was the spectacle correction threshold exceeding the 50th percentile on the basis of a survey of AAPOS members. RESULTS: We completed VAS in 96% of children and NCARS and CR in 100% of children. There was high prevalence (31%) of significant astigmatic refractive error in this sample. Ten subjects who did not permit bilateral visual acuity measurements were scored as having a positive test result. The sensitivity and specificity of VAS were 90% and 44%, respectively. NCARS had sensitivity and specificity of 91% and 86%, respectively. NCARS becomes cost-effective after 1044 children are screened, assuming that the cost of the autorefractor is 300 times the cost of the referral examination. CONCLUSION: VAS offers high sensitivity but suffers from poor specificity. NCARS greatly reduces the number of unnecessary referrals. In this population, NCARS becomes cost-effective after approximately 1000 children are screened.

History of sexual assault and the treatment of substance abuse disorders.

A treatment outcome study of adult patients treated for substance abuse disorders was conducted in which 80% of the participants were successfully contacted for follow-up six months post discharge. Analyses focused on baseline and outcome comparisons of patients with histories of sexual assault and patients with no history of sexual assault. The prevalence of assault in the sample was 15%. Baseline measures indicated that patients in the assaulted group were more likely to have a history of suicide planning and demonstrated greater psychiatric symptom severity as measured by the Brief Symptom Inventory. Outcome measures indicated that treatment was effective for both groups in psychiatric symptom reduction and in reduction of alcohol and other drug use. Results are discussed in terms of specific treatment needs for substance abuse patients with sexual assault histories.

Decision Support Alerts for Medication Ordering in a Computerized Provider Order Entry (CPOE) System: A systematic approach to decrease alerts.

OBJECTIVE: We sought to determine the frequency and type of decision support alerts by location and ordering provider role during Computerized Provider Order Entry (CPOE) medication ordering. Using these data we adjusted the decision support tools to reduce the number of alerts. DESIGN: Retrospective analyses were performed of dose range checks (DRC), drug-drug interaction and drug-allergy alerts from our electronic medical record. During seven sampling periods (each two weeks long) between April 2006 and October 2008 all alerts in these categories were analyzed. Another audit was performed of all DRC alerts by ordering provider role from November 2008 through January 2009. Medication ordering error counts were obtained from a voluntary error reporting system. MEASUREMENTRESULTS: Between April 2006 and October 2008 the percent of medication orders that triggered a dose range alert decreased from 23.9% to 7.4%. The relative risk (RR) for getting an alert was higher at the start of the interventions versus later (RR= 2.40, 95% CI 2.28-2.52; p< 0.0001). The percentage of medication orders that triggered alerts for drug-drug interactions also decreased from 13.5% to 4.8%. The RR for getting a drug interaction alert at the start was 1.63, 95% CI 1.60-1.66; p< 0.0001. Alerts decreased in all clinical areas without an increase in reported medication errors. CONCLUSION: We reduced the quantity of decision support alerts in CPOE using a systematic approach without an increase in reported medication errors.

The influence of a central stimulus on visual field measurements in children from 3.5 to 30 months of age.

PURPOSE: To provide normative data on the effect of a central competing stimulus on monocular visual field extent in 3.5- to 9-month-olds and adults, and binocular visual field extent in 11- to 30-month-olds. METHODS: Visual field extent along diagonal meridia was measured in 180 infants and children (N = 30 at 3.5, 7, 9, 11, 17, and 30 months) and 20 adults, using static perimetry. Stimuli were 3-deg, 10-Hz flickering, yellow light-emitting diodes (LEDs). Each subject was tested with 12 trials in which the central stimulus remained on and 12 trials in which the central stimulus was turned off during presentation of the peripheral stimulus. RESULTS: A competing stimulus produced a decreased frequency of eye movements at 17 months and evidence suggestive of decreased measured field extent at 17 and 30 months. CONCLUSIONS: A continuously present central stimulus does not produce underestimation of visual field extent in 3.5- to 9-month-old infants with normal vision and adults tested monocularly and 11-month-old infants tested binocularly. However, visual field extent may be underestimated in 1- and 2-year-olds if a competing central stimulus is used.

Long-term grating acuity and visual-field development in preterm children who experienced bronchopulmonary dysplasia.

Grating acuity, visual-field extent, and recognition acuity were examined in 77 children who had bronchopulmonary dysplasia (BPD), 101 children who had hyaline membrane disease (HMD), and 77 healthy preterm (HPT) children. None of the subjects had significant retinopathy of prematurity (ROP) or neurological abnormalities. Grating acuity and field extent were tested at 0 to 1, 4, 9, 12, 17, 24, 30, 36, and 48 months corrected age and recognition acuity was tested at 36 and 48 months corrected age. Ophthalmological examinations indicated that a greater proportion of subjects in the BPD group than in the HMD or in the HPT group had strabismus or high refractive error. However, grating acuity and field extent in the BPD group did not significantly differ from the HMD group or from the HPT group at any test age. Recognition acuity was poorer in the BPD and HMD groups than in the HPT group at both 36 and 48 months, but the difference was significant only at 36 months. These results suggest that children who experienced BPD with no significant ROP and no neurological complications show grating acuity and visual-field development comparable to that of healthy preterm children, but that recognition acuity, or the skills required to perform a recognition-acuity task, may be delayed in this BPD population.

Corneal and refractive astigmatism in a sample of 3- to 5-year-old children with a high prevalence of astigmatism.

PURPOSE: To examine the relation between corneal and refractive astigmatism in a sample of pre-school-age Native American children with a high prevalence of astigmatism. METHODS: Subjects were 250 Tohono O'Odham children, 3 to 5 years of age. Each child had corneal astigmatism measured with the Marco Nidek KM-500 portable autokeratometer without pupil dilation, and with the Nikon Retinomax K-Plus portable autorefractor/autokeratometer without and with pupil dilation. Refractive astigmatism was measured using the Retinomax K-Plus, with cycloplegia, confirmed by retinoscopy. RESULTS: Corneal astigmatism exceeded refractive astigmatism, with a median vector dioptric difference of 0.88 D for the KM-500, 0.76 D for the Retinomax K-Plus without dilation, and 0.75 for the Retinomax K-Plus with dilation. The relation between corneal and refractive astigmatism was adequately described by the modification by Grosvenor et al. of Javal's rule, but not by laval's rule. CONCLUSIONS: The results are in agreement with data reported previously for older Native American and non-Native American populations. The modified laval's rule adequately describes the relation between corneal and refractive astigmatism in a population; however, this rule does not provide accurate prediction of refractive astigmatism in individual children or adults.

Grating acuity and visual-field development in children with intraventricular hemorrhage.

Visual development was studied in 171 preterm children who had intraventricular hemorrhage (IVH) and in 73 healthy preterm (HPT) children who did not develop IVH. Binocular grating acuity was assessed at age 1 month; monocular grating acuity and binocular visual-field extent were assessed at 4, 8, 12, 17, 24, 30, 36, and 48 months; and monocular H, O, T, V letter recognition acuity was tested at 36 and 48 months. A significantly greater proportion of IVH subjects than HPT subjects had ocular abnormalities. IVH subjects had significantly poorer grating acuity than HPT subjects at 1, 4, 8, 36, and 48 months, poorer recognition acuity than HPT subjects at 36 and 48 months, and smaller average field extent than HPT subjects at 4, 12, and 17 months. Acuity deficits were not related to grade of IVH or to the presence of periventricular leukomalacia, but may have been associated with the presence of ocular abnormalities or cerebral palsy in some IVH subjects.

Does rate of stimulus presentation affect measured visual field extent in infants and toddlers?

PURPOSE: To evaluate the effect of stimulus presentation rate on the measurement of visual field extent in infants and toddlers. METHODS: Visual field extent was measured for 300 children (N = 60 at 3.5, 7, 11, 17, and 30 months) and 24 adults using hybrid static-kinetic perimetry. Flickering light-emitting diode (LED) stimuli were illuminated sequentially, peripherally to centrally at 10.2 degrees intervals, along 4 diagonal meridia at 2 stimulus presentation rates: 2 s/stimulus (equivalent to 5 degrees/s) and 3 s/stimulus (equivalent to 3 degrees/s). Rate of presentation was a between-subjects variable. RESULTS: No effect of stimulus presentation rate was found for adults. The faster rate of stimulus presentation yielded smaller measured visual field extent for children between the ages of 7 and 30 months. The apparent difference seen with 3.5-month-olds did not reach significance. CONCLUSIONS: Faster rates of stimulus presentation may result in underestimation of visual field extent in children between the ages of 7 and 30 months.

Measurement of refractive error in Native American preschoolers: validity and reproducibility of autorefraction.

PURPOSE: To examine (1) reproducibility of cycloplegic retinoscopy (C-RNS), cycloplegic autorefraction (C-Autoref), and noncycloplegic autorefraction (NC-Autoref), and (2) validity of C-Autoref and NC-Autoref compared with C-RNS in preschoolers with astigmatism. METHODS: Subjects were 36 Native American preschoolers. Three measurements of right eye refractive error were obtained with each of three methods: C-RNS (by three different retinoscopists), C-Autoref, and NC-Autoref (Nikon Retinomax K+). Vector methods (vector dioptric distance, VDD) were used in the analyses. RESULTS: Mean reproducibility was 0.41 D (SD = 0.18) for C-RNS, 0.25 D (SD = 0.17) for C-Autoref, and 0.37 D (SD = 0.21) for NC-Autoref. Mean agreement between C-Autoref and C-RNS ranged from 0.51 to 0.61 VDD (SD = 0.24 to 0.35), and ranged from 1.66 to 1.74 VDD (SD = 1.11 to 1.25) for agreement between NC-Autoref and C-RNS. Mean bias was -0.07 +0.21 x 149 and -1.33 +0.34 x 178 for C-Autoref and NC-Autoref, respectively. CONCLUSIONS: C-Autoref provided reliable and valid measurements of refractive error in young children. NC-Autoref measurements were reliable within subjects, but there was large variability in validity among subjects.

The effect of flicker rate on measured visual field extent in very young children.

PURPOSE: To investigate the effect of flicker rate on measured visual field extent in toddlers. METHODS: A total of 270 full-term children (90 each at 11-, 17-, and 30-months of age) and 36 adults were tested binocularly with an LED static perimetry procedure using a black double-arc perimeter. Each subject was tested with one of three flicker rates: 0, 3, or 10 Hz. The median farthest location seen and an interpolated estimate of the location at which 50% of the subjects detected the peripheral stimulus were calculated for each age group for each flicker rate. RESULTS: For 11-, 17-, and 30-month-old subjects, but not adults, flickering stimuli produced a larger measured visual field extent than nonflickering stimuli. For the 10-Hz stimuli, measured visual field extent in children did not differ from that of adults. CONCLUSIONS: In infants and young children, binocular measured visual field extent is enhanced by peripheral stimulus flicker. Maturity of the measured visual field depends on the stimulus parameters used during testing.

Inter-rater and intra-rater reliability in the interpretation of MTI Photoscreener photographs of Native American preschool children.

PURPOSE: To evaluate inter- and intra-rater reliability for the interpretation of MTI Photoscreener photographs taken in a population of Native American preschool children with a high prevalence of astigmatism. METHODS: Photographs of 369 children were rated by 11 nonexpert and 3 expert raters. Photographs for each child were scored as pass, refer, or retake. Nonexpert raters scored photos on two separate occasions, permitting analysis of intra-rater reliability. RESULTS: Analyses of pass/refer responses only: inter-rater reliability was moderate to substantial among nonexpert raters and substantial among expert raters. Intra-rater reliability among nonexperts was substantial. Analyses of all responses (pass, refer, and retake): inter-rater reliability for pass and refer scores was moderate among nonexperts and substantial among experts; for retake scores inter-rater reliability was slight for nonexperts and moderate for experts. Intra-rater reliability among nonexperts was substantial for pass and refer scores and moderate for retake scores. CONCLUSIONS: In this population with a high prevalence of astigmatism, whether MTI photoscreening results are interpretable is much more variable among and within raters than whether an interpretable photograph should be scored as pass or refer. The level of agreement among raters in the current study was influenced by the experience of the raters. In addition, nonexpert raters were more likely to deem a photograph uninterpretable than expert raters.

Stimulus motion increases measured visual field extent in children 3.5 to 30 months of age.

PURPOSE: To examine the influence of stimulus motion on measured visual field extent of 3.5- to 30-month-old children and adults. METHODS: Each subject was tested with LED-hybrid and LED-kinetic perimetry procedures, using a black double-arc perimeter. Targets in both procedures were identical in size, color, luminance, contrast, and flicker rate. However, in the LED-hybrid procedure, peripheral targets were sequentially illuminated from more peripheral to more central locations, whereas in the LED-kinetic procedure, a peripheral target on a black wand was manually moved centrally along the perimeter arm. A subset of subjects was also tested with white sphere kinetic perimetry (WSKP). RESULTS: The LED-kinetic procedure produced larger measured visual field extent than the LED-hybrid procedure in 3.5-, 11-, 17-, and 30-month-olds, but not in 7-month-olds or adults. Data from subjects tested with WSKP indicated that both stimulus motion and discrepancies in scoring methods contributed to the difference reported previously between visual field measurements obtained with WSKP vs. LED-hybrid perimetry. CONCLUSION: In infants and toddlers, measured visual field extent is larger for moving than for nonmoving targets. Further research is needed to determine whether the effect of motion is related to the visual system or to attentional factors.