Visual Efficiency - Accommodation (Focusing)


Borsting E., Rouse MW,  Chu R. "Measuring ADHD behaviors in children with symptomatic accommodative dysfunction or convergence insufficiency: a preliminary study"  Optometry 2005; 76: 588-92
    Background:  Accommodative dysfunction and convergence insufficiency (CI) are common pediatric vision problems that have been associated with an increase in frequency and severity of vision-specific symptoms that affect children when doing schoolwork. However, the relationship between accommodative dysfunction and CI and other learning problems, such as attention deficit hyperactivity disorder (ADHD), are not well understood. The purpose of this study was to evaluate the frequency of ADHD behaviors in school-aged children with symptomatic accommodative dysfunction or CI.
     Methods:  Children 8 to 15 years of age with symptomatic accommodative dysfunction or CI were recruited from the teaching clinic at the Southern California College of Op tometry. Children with learning disabilities or ADHD were excluded. One parent of each child completed the Conners Parent Rating ScaleRevised Short Form (CPRS-R:S). The childrens scores on the CPRS-R:S were compared with the normative sample.
     Results:  Twenty-four children (9 boys and 15 girls) participated in the study with a mean age of 10.93 years (SD = 1.75). On the CPRS-R:S, cognitive problem/inattention, hyperactivity, and ADHD index were significantly different from normative values (p d .001 for all tests).
     Conclusions:  The results from this preliminary study suggest that school-aged children with symptomatic accommodative dysfunction or CI have a higher frequency of behaviors related to school performance and attention as measured by the CPRS-R:S.

 
Borsting E., Rouse MW, et al. "Association of Symptoms and Convergence and Accommodative Insufficiency in School-Age Children." Optometry 2003; 74: 25-34.
    Abstract:  It was found that Accommodative Insufficiency is common among children aged 8-15 and associated with definite symptoms.  This study included 392 children.
 
Cheng D., Schmid K., Woo G., Drobe B. “Randomized trial of effect of bifocal and prismatic bifocal spectacles on myopic progression.” Arch. Opthalmol. 2010; 128(1): 12-19.

   Objective: To determine whether bifocal and prismatic bifocal spectacles could control myopia in children with high rates of myopic progression.

   Methods: This was a randomized controlled clinical trial.  One hundred thirty-five (73 girls and 62 boys) myopic Chinese Canadian children (myopia of 1.00 diopters [D]) with myopic progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments: (1) single-vision lenses (n = 41), (2) + 1.50-D executive bifocals (n=48), or (3) +1.50-D executive bifocals with a 3-prism diopters base-in prism in the near segment of each lens (n=46). 

   Main Outcome Measures: Myopic progression measured by an automated refractor under cycloplegia and increase in axial length (secondary) measured by ultrasonography at 6-month intervals for 24 months.  Only the data of the right eye were used. 
   Results: Of the 135 children (mean age, 10.29 years [SE, 0.15 years]; mean visual acuity, -3.08 D [SE, 0.10 D]), 131 (97%) completed the trial after 24 months.  Myopic progression average -1.55 D (SE, 0.12 D) for those who wore single-vision lenses, -0.96 D (SE, 0.09 D) for those who wore bifocals, and -0.70 D (SE, 0.10 D) for those who wore prismatic bifocals.  Axial length increased an average of 0.62 mm (SE, 0.04 mm), 0.41 mm (SE, 0.04 mm), and 0.41 mm (SE, 0.05 mm), respectively.  The treatment effect of bifocals (0.59 D) and prismatic bifocals (0.85 D) was significant (P < .001) and both bifocal groups had less axial elongation (0.21 mm) than the single-vision group (P < .001). 

   Conclusions: Bifocal lenses can moderately slow myopic progression in children with high rates of progression after 24 months. 

   Applications to Clinical Practice: Bifocal spectacles may be considered for slowing myopic progression in children with an annual progression rate of at least 0.50 D.


Ciuffreda, KJ. "The Scientific Basis for and Efficacy of Optometric Vision Therapy in Nonstrabismic Accommodative and Vergence Disorders." Optometry 2002; 73: 735-62.

    Abstract:  Using bio-engineering models of the oculomotor system as the conceptual framework, findings clearly support the validity of optometric vision therapy. Furthermore, the results are consistent with the tenets of general motor learning.
 
Cooper J, Fledman J, Selenow A, et al. "Reduction of asthenopia after accommodative facility training."  Am J Optom Physiol Opt, 64:430-6, 1987.
    Abstract: Five patients reporting asthenopia (eye strain) secondary to accommodative deficiencies underwent automated monocular accommodative facility training.  A matched-subjects, crossover design was used to control for placebo effects.  All patients receiving automated accommodative training showed a marked increase in accommodative amplitude along with a concurrent reduction of asthenopia.  Decreases of blur and increases of reading time were the most frequently reported changes by patients.  This experiment shows the effectiveness of automated accommodative training in reducing asthenopia and improving accommodative facility.
 
Culhane HM, Winn B. "Dynamic Accommodation and Myopia." Invest. Ophthalmol. Vis. Sci. 1999 40: 1968-1974.
    Purpose: Accommodative effort during nearwork is thought to be a causative factor in the development of myopia. It has been proposed that an anomaly in autonomic control may be a precursor to the development of myopia. In the present study the closed-loop accommodation response after variations in fixation period was investigated in emmetropes, early-onset myopes and late-onset myopes to determine characteristics of reflex accommodation for each refractive group.   
    Methods: Closed-loop accommodation responses were measured in a group of emmetropes (n = 7), early-onset myopes (n = 7), and late-onset myopes (n = 7) by use of a dynamic tracking infrared optometer. A variation in fixation period (10 seconds, 60 seconds, and 180 seconds) before an accommodative step was used to stimulate the accommodation control mechanism differentially.  
    Results: Group results of accommodative response times showed that late-onset myopes were significantly affected by the duration of fixation before the change in stimulus vergence. Accommodative response times after 3 minutes of sustained near vision were significantly longer than those observed for other groups for the near-to-far condition. Reaction time appears to be independent of refractive grouping, prior fixation period, and direction of step change. 
    Conclusions: Late-onset myopes showed significantly extended accommodation response times after a sustained near vision task that was demonstrable under well-controlled experimental conditions. The extended response times observed in the present study were consistent with previous reports of refractive shifts in late-onset myopes and early-onset myopes and provide a corollary between reflex and adaptive components of the accommodation response. Potential mechanisms are discussed in an attempt to explain the resultant hysteresis under closed-loop viewing conditions
 
Daum KM. "Accommodative insufficiency." Am J Optom Physiol Opt, 60:352-9, 1983. 
    Abstract: A retrospective review of the records of 96 patients with accommodative insufficiency was conducted. The results of orthoptic exercises and/or a plus lens addition at near were examined.  Most patients (90%) obtained some relief with treatment.  About 53% had their objective and subjective problems totally solved during an average treatment period of 3.7 weeks.
 
Davies LN, Wolffsohn JS, Gilmartin B.  "Autonomic correlates of ocular accommodation and cardiovascular function." Opthalmic and physiological optics, 29(4):427-35, 2009. 

     Purpose: To evaluate the hypothesis that objective measures of open- and closed-loop ocular accommodation are related to systemic cardiovascular function, and ipso facto autonomic nervous system activity.
    
Methods: Sixty subjects (29 male; 31 female) varying in age from 18 to 33 years (average: 20.3 ± 2.9 years) with a range of refractive errors [mean spherical equivalent (MSE): 7.12 to +1.82 D] participated in the study. Five 20-s continuous objective recordings of the accommodative response, measured with an open-view IR autorefractor (Shin-Nippon SRW-5000), were obtained for a variety of open- and closed-loop accommodative demands while simultaneous continuous measurement of heart rate was recorded with a finger-mounted piezo-electric pulse transducer for 5 min. Fast Fourier Transformation of cardiovascular function allowed the absolute and relative power of the autonomic components to be assessed in the frequency-domain, whereas heart period gave an indication of the time-domain response.
     Results: Increasing closed-loop accommodative demand led to a concurrent increase in heart rate of approximately 2 beats/min for a 4.0 D increase in accommodative demand. The increase was attributable to a reduction in the absolute (p < 0.05) and normalised (p < 0.001) input of the systemic parasympathetic nervous system, and was unaffected by refractive group. The interaction with refractive group failed to reach significance.
     Conclusions:  For sustained accommodation effort, the data demonstrate covariation between the oculomotor and cardiovascular systems which implies that a near visual task can significantly influence cardiovascular behaviour.  Accommodative effort alone, however, is not a sufficient stimulus to induce automomic differences between refractions groups.  The data suggest that both the oculmotor and cardiovascular systems are predominantly attributable to changes in the systemic parasympathetic nervous system. 

 

Hung GK, Ciuffreda KJ, Semmlow JL. "Static vergence and accommodation: population norms and orthoptics effects." Doc Opthalmologica 62:15-79, 1986. 
    Abstract: This study investigated the effect of orthoptic therapy lasting 8-16 weeks on the accommodative and vergence system function of 22 visually-normal asymptomatic individuals and 21 visually-abnormal symptomatic individuals. Following therapy, asymptomatic individuals experienced reduction of symptoms and improvement in visual parameters toward the normal mean function.
 
Hoffman LG.  "The effect of accommodative deficiencies on the developmental level of perceptual skills."  Am J Optom Physiol Opt, 59:254-62, 1982. 
    Abstract: The relation of accommodative to visual-motor perceptual abilities was investigated.  Patients between 5 and 13 years of age manifesting both accommodative and visual-motor perceptual deficits were given accommodative therapy.  The effect of this therapy was analyzed, and the results indicated that improvement in the visual and motor perceptual abilities occurred in the 5 to 7 years, 11 month age group.
 
Liu JS, Lee M, Jang J, et al. "Objective assessment of accommodation orthoptics. 1. Dynamic Insufficiency."  Am J Optom Physiol Opt, 56:285-94, 1979.
    Abstract: Three young adult females with symptoms related to focusing difficulties at near were treated by standard optometric vision therapy procedures.  Home training was done 20 minutes each day for 4 1/2  7 weeks.  Objective measures of dynamic accommodation were made each week.  During treatment, the patients showed significant reductions in time constants and latencies that correlated well with elimination of subjective symptoms.  Also, in all three patients, symptoms were either markedly diminished or no longer present at termination of therapy. These results clearly demonstrate that optometric vision therapy resulted in objective improvement of accommodation function.
 
Rouse MW  "Management of binocular anomalies: efficacy of vision therapy in the treatment of accommodative deficiencies."  Am J Optom Physiol Optics, (64):415-420, 1987
    Abstract: This paper is a review of the literature supporting optometric vision therapy as an effective treatment mode for accommodative deficiencies.  Optometric vision therapy procedures have been shown to improve accommodative function and eliminate or reduce associated symptoms.  In addition, the actual physiological accommodative response variables modified by the therapy have been identified, eliminating the possibility of Hawthorne or placebo effects accounting for treatment success.  The improved accommodative function appears to be fairly durable after treatment.
 
Sterner B, Abrahamsson M, Sjostrom A. "Accommodative facility training with a long term follow up in a sample of school aged children showing accommodative dysfunction." Doc Ophthalmol 99:93-101, 1999.
    Abstract:  The purpose of this study was to evaluate the effect of accommodative training in a group of children with accommodative dysfunction and subjective symptoms. A total of 38 symptomatic children (ages nine to thirteen) and 24 controls, participated in the study. The length of training varied from 3 to 25 weeks.  A follow-up examination was performed two years after the end of training. The study showed that it is possible to increase relative accommodative by accommodative facility training and minimize subjective symptoms. In the followup evaluation, none of the children had regained any subjective symptoms.
 
Stewart RE, Woodhouse JM, Trojanowska LD. "The use of bifocal spectacles with children with Down's Syndrome." Ophthalmic and Physiological Optics,  25: 514, Nov 2005
    Purpose: Over 75% of children with Down's syndrome fail to accommodate accurately on near targets. This deficit must result in optically blurred images for near work. This present study set out to evaluate the controlled use of bifocal spectacles as an aid to near focusing. Although sometimes used clinically, no systematic studies of bifocals for children with Down's syndrome have been reported.
    Methods: This was a comparative non-randomised interventional study. Thirty-four children with Down's syndrome of primary school age (5-11 years) took part, assigned in equal numbers to form two matched groups. All children received a full optometric assessment prior to entering the study. The treatment group was prescribed bifocal spectacles with a +2.50 addition, and the control group provided with single vision lenses to correct any clinically significant refractive error. Three follow-up visits were made over a 5-month period after spectacle provision.
    Results: The treatment group showed consistently more accurate accommodation than the control group both through the bifocal segment, and, unexpectedly, through the distance part of the lens (p < 0.05).  Compliance with new spectacles was high in both groups (>82% fully compliant).
    Conclusions: Bifocals confer benefit to children with Down's syndrome who under-accommodate, both directly (better focusing through the bifocal) and indirectly (by encouraging improved accommodation through the distance part of the lens). Based on the results of this study, eye examinations of children with Down's syndrome should routinely include a measure of accommodation at near, and bifocal spectacles should be considered for those who show under-accommodation.
 
Suchoff IB, Petito GT.  "The efficiency of visual therapy: accommodative disorders and non-strabismic anomalies of binocular vision."  J Am Optom Assoc, 57:119-25, 1986. 
    Abstract: This paper examines the available literature in order to answer the question, "Is there evidence that `orthoptics' or `vision therapy' causes changes in an individual's accommodative or vergence eye movement systems?" This review neither examines alternative methods of causing these changes nor provides information concerning which particular techniques are most effective although the literature does provide such information. The literature cited substantiates that optometric vision therapy can modify visual functions and also points out the relationship of these changes to the relief of certain symptoms.
 
Tarczy-Hornoch, K. "Modified Bell Retinoscopy: Measuring Accommodative Lag in Children."   Optometry and vision Science, 86(12): 1337-45, 2009 

      Purpose:  to describe a modified bell retinoscopy (MBR) method for quantifying accommodative lag in children and to assess it repeatability and comparability with other techniques.

     Methods: In MBR, the target is advanced toward the patient until the retinoscopic reflex is neutralized. A standardized 40-cm target estimate of lag was derived for each child using data from three retinoscope distances. Within-visit repeatability was assessed in normal children 5 to 23 months of age, a heterogenous group of clinic patients, and a group of children with Down syndrome. Clinic patients were tested on separate days for between-visit repeatability and, also, with Nott retinoscopy (NR) and the monocular estimate method (MEM) on day 2.

     Results: MBR correlated with NR (r = 0.84) and MEM (r = 0.82). MBR and NR estimates were lower than MEM for high lags. Within-visit repeatability of the standardized 40-cm target estimate of MBR in normal children and clinic patients varied with the amount of lag (p < 0.0001). The repeatability index for 0.50 D lag was 0.49 D and for 1.00 D lag it was 0.80 D. Repeatability was similar in children with Down syndrome. In clinic patients, the between-visit repeatability index for 0.50 D lag was 0.60 D for the second estimate of each day, with lower repeatability for the first measure of each day. Repeatability did not vary with age or refractive error. The decrease in repeatability with high lag may be attributable to spatial measurement error.

     Conclusions: MBR estimates of accommodative lag correlate with traditional dynamic retinoscopy measures over a wide range of lags and show comparable repeatability. MBR may be a useful addition to the repertoire of clinical tools available for assessing accommodation in young children.

 

Tosha t, Borsting E, Ridder III WH, Chase C. "Accommodative response and visual discomfortOphthalmic and Physiological Optics, 29(6): 625-33, 2009.

    Purpose:  Although visual discomfort symptoms associated with near work have been correlated with clinical measures of accommodation, studies using objective recordings have not found corresponding deficits in accommodative function. One problem with previous studies is that accommodation measures have been too brief to assess accommodative fatigue. 
   Method: This study examined steady state accommodative responses among a college population with visual discomfort, over a 90-s time period. Thirty-one participants were grouped into high (n = 15) or low visual discomfort groups (n = 16) based on their scores on the Conlon Visual Discomfort Survey. Using the WAM-5500 autorefractor, accommodation responses were recorded at 5 Hz for two consecutive minutes at five viewing distances. 
   Results: The results showed a significant interaction between the high and low discomfort groups over time in accommodation response. The high discomfort group showed an increase in accommodative lag, whereas the low discomfort group had a stable response. Our study suggests that the high visual discomfort group is characterized by accommodative fatigue, with a higher lag of accommodation developing at a near viewing distance over time.
 
Weisz CL.  "Clinical therapy for accommodative responses: transfer effects upon performance."  J Am Optom Assoc, 50:209-12, 1979. 
    Abstract: A clinical therapy program featuring accommodative training was administered to a group of children with diagnosed disorders of accommodative function. The children ranged in age from six to twelve years. A group of subjects representing the same clinical population, and not differing significantly in age or grade level, acted as a control group. The control subjects participated in a therapy program of a similar duration, wherein perceptual-motor training (unrelated to the training of accommodative skills) was administered. A nearpoint pencil-and-paper task was administered to all subjects before and after their training programs, to assess changes in performance as a criterion of learning transfer and behavioral generalization. A significantly greater decrease in errors occurred in the group receiving the accommodative training as contrasted to the control group. No significant differences were found in the time scores. The results suggest that accommodative training, for children with diagnosed accommodative disorders, had transfer effects upon nearpoint performance relating to improved accuracy.
 
Wold, RM, Pierce JR, Keddington, J "Effectiveness of optometric vision therapy." J Amer Optom Assoc, 49:1047-1059, 1978
    Eighty out of 100 children improved in accommodative amplitude (the ability to focus on close objects) and 76 improved in accommodative facility (the ability to adjust focus from near to far) after vision therapy.