Accommodation Insufficiency in Children: Are Exercises Better than Reading Glasses?Strabism 2008; 16:65–69. usCopyright _c 2008 Informa Healthcare USA, Inc.ISSN: 0927-3972 print / 1744-5132 onlineDOI: 10.1080/09273970802039763
ResearchersRune Brautaset,BSc (Optom), MPhil, PhD,Marika Wahlberg,BSc (Optom),Saber Abdi, BSc, MSc(Orthop), PhD,and Tony Pansell,BSc (Optom), PhDUnit of Optometry, Departmentof Clinical Neuroscience,Karolinska Institute, Stockholm,Sweden
Purpose: The aim of the study was to compare efficacy of plus lens (+1.00D) reading addition (PLRA) with that of spherical flipper (±1.50D) in the treatment of accommodative insufficiency (AI).
INTRODUCTION The normal accommodative system is often described as resistant flexible to fatigue Accommodative dysfunction is a relatively common visual anomaly in children and young adults.
INTRODUCTION The prevalence of accommodative dysfunction not associated with presbyopia probably affects at least 2–3% of the population (Rutstein & Daum, 1998).
INTRODUCTION Accommodative dysfunction : Near Work Accommodati ve Insufficiency
INTRODUCTION AI is a condition in which the amplitude of accommodation is chronically the lower limit of the expected amplitude for the patient’s age as measured with push-up accommodative stimuli (Mein & Trimbel, 1994; Benjamin, 1998)
INTRODUCTION AI subjects also demonstrate a reduced accommodation facility (Scheiman &Wick, 1994) Sometimes an lag of accommodation (Rutstein & Daum, 1998; Scheiman &Wick, 1994).
INTRODUCTION AI has been reported to be the most common cause of asthenopia in schoolchildren between 8 and 15 years of age (Borsting et al., 2003).
INTRODUCTION Vision Therapy manifest a range of non-strabismic accommodative and vergence disorders (Abdi et al., 2006).
INTRODUCTION Visual therapy involves purposeful and controlled manipulations of target blur, disparity and proximity, with the aim of normalizing the a c c o m m o d a tiv e s y s te m , the ve rg e nc e s y s te m , a nd m utua l inte ra c tio ns (Griffin & Grisham, 1995; Rutstein & Daum, 1998).
INTRODUCTION The two most important vision therapy regimes for AI areplus lens reading additions (PLRA) (Daum, 1983b; Mazow et al., 1 989; Rutstein & Daum, 1998)
INTRODUCTION PLRA Passive mode of therapy Gives a helping hand in getting a clear retinal image
INTRODUCTION PLRA The amount of blur decreases when wearing glassesRole reduce blur to such an extent that the remaining blur is recognized and within the subject’s accommodative capacity.
INTRODUCTION The subject’s task is to recognise the remaining image blur and to clear the image. However, by being able to clear the image, the blur-driven sensors and the adaptive mechanism within the accommodative system will start to regain normal capacity (Ciuffreda, 2002).
INTRODUCTION the initial amount of blur is not reduced however, a controlled amount of additional blur (with the negative side of the flipper) a controlled amount of reduction in blur (with the positive side of the flipper)
INTRODUCTION The subject’s task is to recognise the change in defocus of the image and to try to respond by obtaining a clear image. By being able to recognise and respond to the blurred image, the blur-driven sensors and the adaptive mechanism within the accommodative system will start to regain normal capacity (Ciuffreda, 2002).
Rationale To clarify the issue of whether PLRA or orthoptic exercises are equally effective or whether one method is more effective than the other.
MATERIALS AND METHODS Partly blind study Consisted of assessments by three examiners. Inclusion criteria E1 E2 E3
MATERIALS AND METHODS Inclusion Criteria: Symptoms revealing uncomfortable vision and/or refractive error less than 1 . 0 0 D o f hy p e rm e tro p ia and less than 0 . 5 0 D o f m y o p ia , and/or a s tig m a tis m le s s tha n 0 . 5 0 D m e a s ure d in c y c lo p le g ia
MATERIALS AND METHODS Inclusion Criteria: distance heterophoria between 2 p d of exophoria and 2 p d of esophoria near (40 cm) heterophoria between 6 p d of exophoria and 4 p d of esophoria near point of convergence of 10 cm or better on the RAF (Royal Air Force) rule
MATERIALS AND METHODS Inclusion Criteria: fusional reserve at least twice the near phoria near point of accommodation worse than (100/ (15D-(0.4 age))) on the RAF rule distance Snellen visual acuity of 0.8 or better both monocularly and binocularly normal ocular motility
MATERIALS AND METHODS Inclusion Criteria: full stereo vision on the Lang II test no ocular pathology no history of ophthalmologic treatment not taking any drugs with a known effect on visual acuity and/or binocular function and accommodation.
MATERIALS AND METHODS E1 asked the subjects to consecutively participate in the study. 24 subjects with AI (age: 10.3 ±2.5 ) 24 10 14 10 subjects-8 weeks of PRLA 9 subjects-8 weeks of treatment Flipper treatment Age : 10.3 years ±2.74 5 drop outs Age: 10.3 years ±2.41
MATERIALS AND METHODS If the subject met the inclusion criteria, the subject was seen by a second examiner (E2) who, without knowing the results of the inclusion examination, performed measurements of the study variables. E2
MATERIALS AND METHODS Study variables: E2 Accommodative amplitude Accommodative facility Lag of accommodation Visual Analogue Scale (VAS) score
MATERIALS AND METHODS were those assessed? AA- three measurements were taken AF- accommodative facility at 40 cm with a ±2.00D flipper while fixating a vertical row of letters equivalent to 6/9 visual acuity (measured binocularly and in the dominant eye; dominance was tested with the Miles test (Michaels, 1975))
MATERIALS AND METHODS were those assessed? lead/lag of accommodation as measured with N tt d y na m ic re tino s c o p y while fixating a vertical o row of letters equivalent to 6/9 visual acuity at 40 cm subjective grading of the degree of asthenopia on a Visual Analogue Scale (VAS)
MATERIALS AND METHODS A visual analogue scale (VAS) is a psychometric response scale which can be used in questionnaires. It is a measurement instrument for subjective characteristics or attitudes that cannot be directly measured. Numbering from 0-10.
MATERIALS AND METHODS If 0 equals no problem when doing near work and 10 equals the worst degree of problems, what number would you grade your problems at near work to be now?” These four measures were repeated after the 8 weeks’ treatment period.
MATERIALS AND METHODS E3 The subject was then seen by a third examiner (E3) who, according to a randomization list and without knowing the results obtained by E1 and E2, assigned the subjects to either flipper or PLRA treatment.
MATERIALS AND METHODS E1 examination E2 performed Included in study examination Mixed samples who met inclusion criteria E3 assigned glasses E3 assigned flipper randomly treatment randomly E2 performed follow up examination at 8 weeks
MATERIALS AND METHODS E3 24 subjects with AI (age: 10.3 ±2.5 ) 24 10 1410 subjects-8 weeks of PRLA 9 subjects-8 weeks of treatment Flipper treatment Age : 10.3 years ±2.74 5 drop outs Age: 10.3 years ±2.41
MATERIALS AND METHODS After 8 wks, re- examination by E2 without knowing the kind of treatment.
Flipper PLRA ±1.50D flipper lenses +1.00 lenses Two sessions of nine minutes each day To be done when not tired or not feeling asthenopia Done at 40 cm Done as many flips a minute.
Flipper PLRA followed by another use the glasses as one-minute trial of much as possible for flipping and a one- all types of near minute break. visual work. repeated until the subject had done a total of five minutes of flipping Target
Statistical Methods The effect of treatment (before vs. after), the type of therapy regime (flipper vs. PLRA) and the interaction effect between them were analysed using multivariate analysis of variance.
Statistical Methods Bonferroni post-hoc analysis Planned comparison. Wilcoxon matched pair test was used for analysis of the VAS score and the within-group results A significance level of 0.05 was considered significant. Dropouts have not been included in the analysis.
RESULTS Accommodative Amplitude and Accommodative Facility Significant interaction between the study variables and the treatment [F(2,34) = 6.97, p = 0.003]. The post hoc analysis showed a significant change in accommodative amplitude [F(1,17) = 18.84, p < 0.001].
RESULTS Accommodative amplitude change over a period.
RESULTS Accommodative facility change over a period.
RESULTS Flipper vs. PLRA The analysis did not reveal any statistically significant difference between the two therapy regimes [F(1,17) = 0.31, p = 0.58]. With the accommodative response excluded, the difference was still not significant [F(1,17) = 2.06, p = 0.17].
RESULTS VAS Flipper PLRA 6.3 units lower 4.7 units lower after treatment after treatment [Z(n = 9) = 2.66; p [Z(n = 10) = 2.80; = 0.008] p = 0.005]
DISCUSSION Visual therapy in AI involves Purposeful and controlled manipulations of target blur, disparity and proximity with the aim of normalizing the accommodative system (Griffin & Grisham, 1995; Rutstein & Daum, 1998).
DISCUSSION The two most commonly used regimes of therapy for AI are fundamentally different. PLRA is a much more passive type of treatment as compared with flipper treatment. However, in both regimes, the aim is to improve the response of the blur-driven sensors and the adaptive mechanisms within the accommodative system so that they can regain normal capacity (Ciuffreda, 2002).
DISCUSSION The purpose of the present study was to evaluate which mode of therapy PLRA FLIPPER is a more
DISCUSSION Expected values for accommodative amplitude in the age range tested in this study are between 14.0 and 16.5D (Rutstein & Daum, 1998). This is less than the improvement found by Abdi et al. (2007) over a 12-week treatment period with the same +1.00D reading addition and less than that found by Daum (1983b).
DISCUSSION The results of the present study show that both methods improve accommodative amplitude. The improvement with PLRA was from 3.58D to 4.25D.
DISCUSSION With accommodative amplitude improved from 5.16D to 7.82D, a significant improvement which occurred due to good compliance.Daum (1983)
DISCUSSION Present study results Sterner et al. (2001).The amount of treatment and the treatment time werecomparable to the treatment regime used in thisstudy.
DISCUSSION The expected binocular values for accommodative facility are between 6 and 10 cpm (Rutstein & Daum, 1998).Before treatment, all subjects performed worse on accommodative facility. After treatment, all subjects reached values just within the normal range, irrespective of the treatment regime. Despite this, the improvement was small and not statistically significant (p = 0.06).
DISCUSSION VAS Before treatment, all subjects included had a grading of much more than 2 (7.3 and 8.1 on average in the PLRA and flipper groups, respectively).
DISCUSSION The reduction in VAS score was significant in both groups, but only in the flipper group was an average VAS score below 2 achieved. The higher level of improvement in accommodative amplitude and the lower VAS score after treatment in the flipper treatment group indicates that the treatment time needed will be shorter with this type of treatment as compared with PLRA.
DISCUSSION On the other hand, the fact that dropout only occurred in the flipper treatment group indicates that it m a y be m o re d iffic ult to m o tiv a te s ubje c ts to d o o rtho p tic e x e rc is e s a s c o m p a re d to we a ring re a d ing g la s s e s .
CONCLUSION The results indicate that both methods improve the accommodative amplitude, but that overall accommodative function reaches higher levels of improvement with spherical flipper as compared with PLRA treatment. However, the accommodative function did not gain normal values in 8 weeks of treatment with either regime.