accommodation insufficiency treatment

JOURNAL CLUBACCOMMODATIVE INSUFFICIENCY…

Amrit Pokharel

Accommodation Insufficiency in Children: Are Exercises Better than Reading Glasses?

Strabismus 2008; 16:65–69. Copyright _c 2008 Informa Healthcare USA, Inc. ISSN: 0927-3972 print / 1744-5132 online DOI: 10.1080/09273970802039763

Researchers

Rune 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

Accommodative dysfunction is a relatively common visual anomaly in children and young adults.

flexible resistant to fatigue

INTRODUCTION

The prevalence of accommodative dysfunction

probably affects at least 2–3% of the population (Rutstein & Daum, 1998).

not associated with presbyopia

INTRODUCTION

Accommodative dysfunction :

Near Work

Accommodative

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

manifest a range of non-strabismic accommodative and vergence disorders (Abdi et al., 2006).

Vision Therapy

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 da tive 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 are

(Daum, 1983b; Mazow et al., 1 989; Rutstein & Daum, 1998)

plus lens reading additions (PLRA)

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 glasses

Role 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.

E1 E2

E3

Inclusion criteria


Inclusion Criteria: Symptoms revealing uncomfortable vision

and/or

refractive error less than 1 . 0 0 D o f hyp 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


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


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


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.


E1 asked the subjects to consecutively participate in the study.

10 subjects-8 weeks of PRLA treatment

Age : 10.3 years ±2.74

24

10

24 subjects with AI(age: 10.3 ±2.5 )

9 subjects-8 weeks of Flipper treatment

5 drop outs Age: 10.3 years ±2.41

14


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


Study variables:

Accommodative amplitude Accommodative facility Lag of accommodation Visual Analogue Scale (VAS) score

E2


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))


were those assessed? lead/lag of accommodation as measured with

No tt d yna m ic re tino s c o p y while fixating a vertical 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)

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.



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.


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.

E3


E3 assigned glasses randomly

E3 assigned flipper treatment randomly

Mixed samples who met inclusion

criteria

E2 performed follow up examination at 8 weeks

E1 examination Included in study

E2 performed examination


10 subjects-8 weeks of PRLA treatment

Age : 10.3 years ±2.74

24

10

24 subjects with AI(age: 10.3 ±2.5 )

9 subjects-8 weeks of Flipper treatment

5 drop outs Age: 10.3 years ±2.41

14

E3


After 8 wks, re-examination by E2

without knowing the kind of treatment.

±1.50D flipper 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.

+1.00 lenses

Flipper PLRA

followed by another one-minute trial of flipping and a one-minute break.

repeated until the subject had done a total of five minutes of flipping

Target

use the glasses as much as possible for all types of near visual work.

Flipper PLRA

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

Flipper6.3 units lower after treatment

[Z(n = 9) = 2.66; p = 0.008]

PLRA4.7 units lower after treatment

[Z(n = 10) = 2.80; 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

is a more

PLRA FLIPPER

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 were comparable to the treatment regime used in this study.

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

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).

VAS

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 tiva 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.

Thank You

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