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Biomedical subjects

Robert W Arnold

Publications and source records attributed to Robert W Arnold.

At least 19 recordsLinked to original sources
PubMed2006

Treatment of anisometropic amblyopia in children with refractive correction.

OBJECTIVE: To evaluate the effectiveness of refractive correction alone for the treatment of untreated anisometropic amblyopia in children 3 to <7 years old. DESIGN: Prospective, multicenter, noncomparative intervention. PARTICIPANTS: Eighty-four children 3 to <7 years old with untreated anisometropic amblyopia ranging from 20/40 to 20/250. METHODS: Optimal refractive correction was provided, and visual acuity (VA) was measured with the new spectacle correction at baseline and at 5-week intervals until VA stabilized or amblyopia resolved. MAIN OUTCOME MEASURES: Maximum improvement in best-corrected VA in the amblyopic eye and proportion of children whose amblyopia resolved (interocular difference of < or =1 line) with refractive correction alone. RESULTS: Amblyopia improved with optical correction by > or =2 lines in 77% of the patients and resolved in 27%. Improvement took up to 30 weeks for stabilization criteria to be met. After stabilization, additional improvement occurred with spectacles alone in 21 of 34 patients observed in a control group of a subsequent randomized trial, with amblyopia resolving in 6. Treatment outcome was not related to age, but was related to better baseline VA and lesser amounts of anisometropia. CONCLUSION: Refractive correction alone improves VA in many cases and results in resolution of amblyopia in at least one third of 3- to <7-year-old children with untreated anisometropic amblyopia. Although most cases of resolution occur with moderate (20/40-20/100) amblyopia, the average 3-line improvement in VA resulting from treatment with spectacles may lessen the burden of subsequent amblyopia therapy for those with denser levels of amblyopia.

Amblyopia↗
PubMed2006

A randomized trial to evaluate 2 hours of daily patching for strabismic and anisometropic amblyopia in children.

OBJECTIVE: To compare 2 hours of daily patching (combined with 1 hour of concurrent near visual activities) with a control group of spectacle wear alone (if needed) for treatment of moderate to severe amblyopia in children 3 to 7 years old. DESIGN: Prospective randomized multicenter clinical trial (46 sites). PARTICIPANTS: One hundred eighty children 3 to 7 years old with best-corrected amblyopic-eye visual acuity (VA) of 20/40 to 20/400 associated with strabismus, anisometropia, or both who had worn optimal refractive correction (if needed) for at least 16 weeks or for 2 consecutive visits without improvement. INTERVENTION: Randomization either to 2 hours of daily patching with 1 hour of near visual activities or to spectacles alone (if needed). Patients were continued on the randomized treatment (or no treatment) until no further improvement was noted. MAIN OUTCOME MEASURE: Best-corrected VA in the amblyopic eye after 5 weeks. RESULTS: Improvement in VA of the amblyopic eye from baseline to 5 weeks averaged 1.1 lines in the patching group and 0.5 lines in the control group (P = 0.006), and improvement from baseline to best measured VA at any visit averaged 2.2 lines in the patching group and 1.3 lines in the control group (P<0.001). CONCLUSION: After a period of treatment with spectacles, 2 hours of daily patching combined with 1 hour of near visual activities modestly improves moderate to severe amblyopia in children 3 to 7 years old.

Amblyopia↗
PubMed2006

A comparison of patched HOTV visual acuity and photoscreening.

Early detection of significant vision problems in children is a high priority for pediatricians and school nurses. Routine vision screening is a necessary part of that detection and has traditionally involved acuity charts. However, photoscreening in which "red eye" is elicited to show whether each eye is focusing may outperform routine acuity testing in pediatric offices and schools. This study compares portable acuity testing with photoscreening of preschoolers, kindergarteners, and 1st-graders in 21 elementary schools. School nurses performed enhanced patched acuity testing and two types of photoscreening in a portable tent. Nearly 1,700 children were screened during spring semester 2004, and 14% had confirmatory exams by community eye care professionals. The results indicate that one form of photoscreening using a Gateway DV-S20 digital camera is significantly more sensitive to children with significant vision problems, as well as being the most cost effective (85% specificity and only $0.11 per child). This suggests that the adaptation of photoscreening into a routine vision screening protocol would be beneficial for efficiently detecting vision problems that could lead to amblyopia.

Alaska↗
PubMed2006

The yield and challenges of charitable state-wide photoscreening.

INTRODUCTION: State-wide cooperative programs for pediatric vision screening utilizing the MTI photoscreener and centralized interpretation were established in Alaska (The Alaska Blind Child Discovery, ABCD) and in Tennessee (Tennessee Lions Outreach). METHODS: Details of setup, implementation and interpretation of the state-wide MTI photoscreening programs are compared through 2002. The absolute numbers of children screened and the breakdown in interpretation categories are presented. RESULTS: ABCD screened 14,000 children while Tennessee Lions screened 100,800. Similarities between ABCD and Tennessee programs were funded by Lions Clubs and other charitable and public health organizations, community screening and each had coordinated centralized image interpretation and notification. The programs differed by clinic focus (Tennessee Lions organized pre-schools while ABCD used village and community health fairs and schools), parent notification (Tennessee Lions communicated through pre- schools and ABCD mailed directly to parents), and image interpretation (Tennessee used VOIC age-based and pupil-size crescents while ABCD used "delta-center crescent"). Predictive value positive was 73% for Tennessee and 89% for ABCD. Tennessee achieved better followup on referrals after a specific coordinator was employed. Image interpretation breakdown for ABCD: Tennessee Lions Outreach were anisometropia (29%:34%), high hyperopia (33%:16%), astigmatism (18%:30%), strabismus (7%:15%), myopia (5%:2%), cataract (0.7%:0.2%). Two state-wide programs detected 3216 amblyopic children at a charity borne-cost of 1.5 million dollars. If the parents persisted with appropriate amblyopia therapy, the expected societal value was estimated at 17 million dollars. Lacking societal mandate and funding, these concerted charitable efforts only achieved a community penetration rate of 10% to 14%. CONCLUSION: National adoption of preschool vision screening by a method with similar or even better validity and cost effectiveness as MTI photoscreening, ideally in the pediatric medical home, is warranted.

Alaska↗
PubMed2005

Is Pacific race a retinopathy of prematurity risk factor?

BACKGROUND: Black race affords some protection from retinopathy of prematurity (ROP), but more ROP was previously found in another darkly pigmented race, the Alaskan natives. DESIGN: From fall 1989 through summer 2003, all Alaskan infants with a birth weight of 1500 g or less were examined, documenting mother's stated race, prenatal care, and neonatal intensive care unit course. RESULTS: Retinopathy of prematurity was classified as to predefined threshold for peripheral ablative treatment (region of avascular retina and fibrovascular ridge and vessel tortuosity) in 873 infants. Threshold ROP was more prevalent in Alaskan natives (24.9%) and Asians (15.9%) (10% overall), with no significant difference between Alaskan natives and Asians (P = .24). Alaskan native males had more threshold ROP (69%) compared with non-Alaskan native males (51%). Compared with threshold nonnatives, Alaskan native threshold infants had greater birth weights (829 +/- 222 vs 704 +/- 186 g), required less time on ventilation (46 +/- 22 vs 70 +/- 75 days), and progressed to treatment at a younger age (35.5 +/- 2.2 vs 36.2 +/- 2.6 weeks' gestational age) (data are given as mean +/- SD). CONCLUSIONS: In this limited study, we find increased risk of threshold ROP in 2 northern Pacific races. Threshold Alaskan natives had similar or better prenatal and neonatal intensive care unit variables than did threshold nonnatives; however, Alaskan native males were still at a greater risk.

Alaska↗
PubMed2005

A randomized pilot study of near activities versus non-near activities during patching therapy for amblyopia.

BACKGROUND: To plan a future randomized clinical trial, we conducted a pilot study to determine whether children randomized to near or non-near activities would perform prescribed activities. A secondary aim was to obtain a preliminary estimate of the effect of near versus non-near activities on amblyopic eye visual acuity, when combined with 2 hours of daily patching. METHODS: Sixty-four children, 3 to less than 7 years of age, with anisometropic, strabismic, or combined amblyopia (20/40 to 20/400) were randomly assigned to receive either 2 hours of daily patching with near activities or 2 hours of daily patching without near activities. Parents completed daily calendars for 4 weeks recording the activities performed while patched and received a weekly telephone call in which they were asked to describe the activities performed during the previous 2 hours of patching. Visual acuity was assessed at 4 weeks. RESULTS: The children assigned to near visual activities performed more near activities than those assigned to non-near activities (by calendars, mean 1.6 +/- 0.5 hours versus 0.2 +/- 0.2 hours daily, P < 0.001; by telephone interviews, 1.6 +/- 0.4 hours versus 0.4 +/- 0.5 hours daily, P < 0.001). After 4 weeks of treatment, there was a suggestion of greater improvement in amblyopic eye visual acuity in those assigned to near visual activities (mean 2.6 lines versus 1.6 lines, P = 0.07). The treatment group difference in visual acuity was present for patients with severe amblyopia but not moderate amblyopia. CONCLUSIONS: Children patched and instructed to perform near activities for amblyopia spent more time performing those near activities than children who were instructed to perform non-near activities. Our results suggest that performing near activities while patched may be beneficial in treating amblyopia. Based on our data, a formal randomized amblyopia treatment trial of patching with and without near activities is both feasible and desirable.

Activities of Daily Living↗
PubMed2004

Vision screening for children: current trends, technology, and legislative issues.

PURPOSE OF REVIEW: The purpose of this review is to examine current trends in vision screening for children. RECENT FINDINGS: Literature within the past year regarding children's vision screening has been dominated by clinical validation studies of autorefractors or photoscreeners that allow the detection of amblyogenic refractive errors, misalignment of the eyes, or media opacities. New technologies reported include wave-front analysis for amblyogenic factors and a visual evoked potentials-based screening tool for the preverbal child. Studies evaluating the goals of the screening program, the target population, and the physical limitations of the screening environment have prompted multipronged or hybrid studies designed to more accurately detect vision problems, particularly in the preschool child, in whom cooperation and cognitive development affect reliability of results. State and federal legislation in the United States has been proposed or adopted to regulate and partially fund pediatric vision screening and comprehensive examinations. SUMMARY: Through improvements and new developments in technology, study design, the efforts of organized medicine, and legislative initiatives, vision screening for children continues toward the goal of bringing all children with eye disease or vision problems to treatment in a timely fashion.

Child↗
PubMed2004

Pseudo-false positive eye/vision photoscreening due to accommodative insufficiency. A serendipitous benefit for poor readers?

BACKGROUND: Children whose eyes and vision are otherwise normal and who should screen negatively as normals, but who fail to compensate for their normal mild hyperopia (i.e. by normally accommodating, or rather actually failing to accommodate) will generate hyperopic crescents in a photoscreen test that can be interpreted as "positive" (for pathology) because high and asymmetric levels of hyperopia are common risk factors for amblyopia. This would therefore usually be considered a "false positive" and no further care would be offered. However, this failure to compensate, may in fact be a pathological disorder, accommodative insufficiency, making this apparently "false positive" situation actually a actually a "false-positive-false- negative positive test", or more simply a "false- false positive test". METHODS: The Alaska Blind Child Discovery Project photoscreened just under 16,000 children referring 6% as "positive", of which, after examination, the false positive rate was just 6% of those referred (0.4% of the total number screened). RESULTS: Ten (42%) of the 24 false positives had evidence of accommodative insufficiency inspite of only average (for age) amounts of cycloplegic hyperopia and a lag of accommodation on dynamic retinoscopy. Eight of the 10 were boys of kindergarten age. Most of these subsequently benefitted from prescription and use of reading glasses of low plus sphere correction. CONCLUSION: About 0.15% of photoscreened children, or 2.5% of those screening positive, and 42% (10/24) found initially on exam to be falsely positive, yielding hyperopic interpretations despite low and usually acceptably normal for age amounts of hyperopia, are in fact suffering from a pathological accommodative insufficiency. Identification of such false- false positives by a combination of photoscreening and dynamic retinoscopy may be used to determine which students might be helped with enforced reading glasses. Confirmatory exams on photoscreen positive-hyperopia cases should include an assessment of accommodation to identify these children.

Accommodation, Ocular↗
PubMed2004

Duration and effect of single-dose atropine: paralysis of accommodation in penalization treatment of functional amblyopia.

BACKGROUND AND PURPOSE: Atropine dilates the pupil and paralyzes the ciliary muscle accommodation, blurring vision, and therefore is an effective penalization of the sound eye in the treatment of functional amblyopia of the other eye. The degree of blur induced is a function of the amount of the patient's uncorrected hyperopia and the distance from the eye of the viewed material or object. Another factor determining effectiveness of atropine penalization is the duration of the effect of the atropine. It is the purpose of this study to investigate these factors. METHODS: Six normal children underwent complete eye exam with cycloplegic refraction several days before deliberate instillation of atropine 1% in the sound, or right eye. Distance and near acuity was then tested after 30 minutes, and on subsequent days. Additional data points were derived by placing known minus lenses in front of the tested eye. In addition, we also studied one successfully treated amblyopic patient when he terminated chronic daily atropine in his normal, sound eye. RESULTS: Atropine initially produced a linear reduction in logMAR acuity (blur) at distance of about 0.2 logMAR lines per diopters of uncorrected hyperopia. The magnitude of the blur was greater for near, but the effect of increased hyperopia was slightly greater for distance measurements. This blurring of acuity lasted just less than 48 hours for normal subjects, and just over 48 hours following prompt cessation of chronic daily atropine in that one subject. Regression formulae were derived relating uncorrected hyperopia and time interval following atropine cessation on distance and near acuity in children of amblyopic age range. CONCLUSION: The degree of penalization is highly dependent on the uncorrected hyperopic refractive error. A significant penalization effect is present only for one day or so. Daily atropine is therefore indicated for penalization. To better tailor penalization therapy to target sound eye acuity blur, these formulae and graphs can be used, specifically, in addition, to determine the amount of deliberate spectacle hyperopic undercorrection to maximize the penalization effect.

Accommodation, Ocular↗
PubMed2004

The profound augmentation of the oculocardiac reflex by fast acting opioids.

BACKGROUND: Trigemino-vagal bradycardia elicited by tension on an extraocular muscles (oculocardiac reflex; OCR) is a hazard for strabismus surgery patients. OCR can be reduced by anticholinergic medications and regulating the depth of anesthesia. We investigated the influence of narcotic agents as a routine part of general anesthesia for strabismus surgery in adults and children. METHOD: From August, 1992 through September, 2000, 1275 patients undergoing extraocular muscle surgery were prospectively studied during 10 second, 200 gram square wave tension on gently isolated rectus muscles. The anesthetic agents, gas concentrations, and patient age were recorded. Patients receiving an anticholinergic agent and reoperated cases were excluded, yielding 1029 study cases. 849 received no narcotic as a part of induction. Two groups of patients were given no opiate before the first inferior rectus muscle was pulled. A narcotic was administered IV 5 minutes before the second inferior rectus was pulled. One group of 49 received fentanyl 0.15 uL/Kg and the second group of 12 received meperidine 1 mg/kg. RESULTS: Faster acting intravenous induction opioids had a profound augmenting effect on the degree of oculocardiac reflex. Compared to no narcotic, the OCR was increased most by remifentanyl (p less than .0001), then sufenta (p=.02), and fentanyl (p less than .0001). Induction morphine had no appreciable effect on the OCR (p=.9). For the 49 patients with IV fentanyl delivered between the first OCR and second OCR, a significant increase occurred (p=.003). This increase in %OCR was not correlated with a change in inhalational gas concentration (p=.9), CO2 concentration (p=.6) or age (p=.12). For the 12 patients given demerol between the first and second rectus tension, no significant OCR change occurred (p=.7). The OCR was greatest for inferior rectus, then superior rectus, then medial rectus, and least for lateral rectus. (See text for details.) CONCLUSION: In the absence of anticholinergic blockade, rapidly acting narcotics enhance the degree of bradycardia due to the OCR elicited by controlled extraocular muscle tension during strabismus surgery. Some opioids had the same augmenting magnitude as the blocking effect of IV anticholinergic medication. Meperidine, which has some anticholinergic characteristics, neither blocked nor augmented the OCR.

Adolescent↗
PubMed2003

The phoropter trapeze. A portable refractive support for remote clinics.

A trapeze was engineered using inexpensive pre-threaded commercial polyvinyl chloride ("PVC") plumbing pipe. This was suspended from a convenient overhead point and the phoropter was clamped to it. It was stabilized by the patient holding on two attached handles. Illustrated in photographs.

Ambulatory Care Facilities↗
PubMed2003

The effect of induced muscle tension and fatigue on the oculocardiac reflex.

INTRODUCTION: We investigated surgeon-modified factors in the oculocardiac reflex (OCR) including repeating tension after return to baseline pulse (fatigue) or modifying the tension place on the extraocular muscle (EOM). METHODS: A control group of 842 adult and pediatric strabismus cases underwent controlled, 200 gram, 10-second square wave tension on at least two EOM. The effect of TENSION was studied in 90 random cases by placing a tension of 50 grams on one of the later muscles and a tension of 400 grams on another subsequent muscle. The effect of FATIGUE was studied in 30 cases when the initial tension elicited a profound bradycardia. The heart rate was allowed to return to within 96% of pre-tension levels, and the same muscle had a second identical tension. RESULTS: For the 842 control cases, aged 12 +/- 16 (s.d.) years, initial 200 gram OCR was -16.9 +/- 19% and the second muscle 15 +/- 7 minutes later was significantly less percent change -14.6+/- 17%, paired t=3.9, p= .0001. TENSION: OCR was a similar reduction of 16-18% for 200 gram and 400 gram tension but had a modest reduction of 10% for 50 gram EOM tension. FATIGUE: For cases with profound initial OCR, waiting 3 minutes produced only a 17% reduction in OCR severity. CONCLUSION: A surgeon can reduce oculocardiac reflex by exerting very gentle 50 gram tension on the EOM or waiting for return to baseline heart rate before fatiguing the reflex. These reductions are of less clinical value than pharmacologic intervention.

Adult↗
PubMed2002

The attenuating effect of intraglossal atropine on the oculocardiac reflex.

INTRODUCTION: Bradycardia during strabismus surgery is reduced better by intravenous than by intramuscular (deltoid) anticholinergics, but recent studies suggest that injection into the tongue works faster than into the deltoid. We sought to study this using the suppression of the oculocardiac reflex during eye surgery as a parameter. METHODS: 804 children and adults underwent calibrated extraocular muscle tensioning during controlled, inhalational general anesthesia. A systemic anticholinergic agent was distributed by different routes to patient-subject sub-groups: preoperative oral, or induction intravenous, intramuscular (deltoid) and intraglossal (submucosal at the base of the tongue). A large control group received no anticholinergic. RESULTS: The control group had an oculocardiac reflex averaging 17.2% heart rate reduction (bradycardia), 6% of whom had greater than a 50% heart rate reduction. This oculocardiac reflex bradycardia was reduced to only a 6.7% heart rate reduction by oral and intradeltoid routes and was essentially eliminated by both intravenous (-2.3%) and intraglossal (-0.9%) routes. CONCLUSION: Intraglossal atropine is an effective alternative for oculocardiac reflex prophylaxis when intravenous access is not readily available in strabismus surgery. The intraglossal route is in fact slightly more effective in this regard that the intravenous route per se.

Adolescent↗