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  5. FP217 : Effectiveness of Modified Glass Prescription & Smartphone Based Exercises in Fusion Insufficiency

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Dr. Amit Mohan, M11516, Dr. Manju Gajraj, Dr. Shalini

Abstract

Purpose: To determine the effectiveness of modified glass prescription with Smartphone based fusion exercises in young adult with fusion insufficiency. Methods: A total of 150 patients using glasses and having asthenopia between 15-30 yrs of age were subjected to thorough eye examination including binocular vision testing and refraction. Of them 26 individuals have convergence insufficiency with fusion weakness and exophoria< 8pd without any manifest strabismus, amblyopia and ocular diseases were chosen, modified glasses (overcorrection of myopia by -0.5 DSph& under correction of hypermetropia by +0.5DSph) were given along with Smartphone based exercise.

Results: Near point of convergence improved by 2.89+_1.08 cm, positive fusion vergence by -10.2+_3.25pd and near phoria by 3.13+_0.32pd (p<0.001). Conclusion: Study focuses on the need to take account of phoria in prescribing glasses in symptomatic fusion insufficiency and android based exercise to recover from symptoms. 

Full text

Introduction

Convergence and fusion insufficiency is defined as binocular disorder in which eyes do not work well at near fixation. Approximately 3-5% of the general population are affected by convergence and fusion insufficiency.[1]  26% population of fusion weakness are wearing spectacles. Symptoms of fusion insufficiency are asthenopia, headache, intermittent blur for near, diplopia, burning sensation and epiphora.[2]There are various treatment options for fusion weakness such as correcting refractive errors, prescribing glasses or orthoptic exercises.[3]  Several studies demonstrated that significant improvement of symptoms and clinical signs of near point of convergence (NPC) and positive fusionalvergence (PFV) measures following orthoptic exercise. Here we have used smartphone based fusion exercise in place of conventional exercise and demonstrated its effectiveness.

Material & methods

A total of 150 young adults, aged 15-30 years who attended our outpatient department of strabismus clinichaving asthenopic symptoms and using glasses regularly were enrolled for study.Examination included history about symptoms, distance and near visual acuity, cover test, NPC (RAF ruler), ocular motility, fusion (Worth 4 dot test) and stereopsis (TNO test).

Refractive errors were determined using an autorefractor and subjective refractionand was performed using monocular fogging method with cross cylinder, followed by binocular balancing to a standard endpoint of maximum plus for best corrected visual acuity.

The binocular visual system were examined including NPC , positive fusional amplitude and prism cover test for distance and near.

Diagnostic criteria for convergence insufficiency are

  • Symptoms associated with reading
  • Signs:

Moderate to high exophoria at near >6pd

Reduced positive fusionalvergence at near

Receded near point of convergence

All participants with convergence insufficiency were prescribed 0.5 Dsphunder correction of plus glasses and overcorrection of minus glasses to ensure to use their accommodation.

Eye Exercises is available on Android for free. We suggest everyone with a spare bit of time give this app a try. All of them followed an 8 weeks of smartphone based fusion exercise of different level (Eye gym exercise available freely atplay store developed by Singapore national eye centre.) daily home therapy session of 15 minutes per day.

Criteria for the improvement were as follows:

  • Symptoms were absent
  • NPC or PFV improved to the normal value ( NPC < 8cm and PFV >35 pd)

Analyses were conducted including descriptive statistics and paired t-test using SPSS (version 16.0 for windows, SPSSInc. Chicago, IL) P <0.05 was considered significant.

Results

A total of 150 patients using glasses and having asthenopia between 15-30 yrs of age were subjected to thorough eye examination including binocular vision testing and refraction. Of them 26 individuals have convergence insufficiencies with fusion weakness and exophoria< 8pd without any manifest strabismus were chosen. Subjects with amblyopia and other ocular diseases were excluded from the study. Modified glasses (overcorrection of myopia by -0.5 DSph& under correction of hypermetropia by +0.5DSph) were prescribed along with Smartphone based exercise.

Table-1 summarizes the detailed results of modified glass prescription and smartphone based exercise for convergence and fusion weakness .

Before intervention After intervention P value
NPC (cm) 10.41+_1.69 7.52+_0.61 <0.001
PFV (pd) break 24.85+_4.17 35.05+_3.85 <0.001
Phoria near (pd) 7.45+_1.56 4.32+_1.24 <0.001
Phoria distance (pd) 3.69+_1.25 2.25+_0.65 <0.001

During 1-2 weeks after starting the therapy some participants complained of eyestrains which can be results of getting used to of newer glasses and orthoptic exercises. After 8 weeks of intervention 22 participants (84.61%) have reached the aim of treatment. The effect of treatment on NPC, PFV and near phoria is highly significant (p<0.001). 

Discussion

In our study modification of glasses along with smartphone based exercise increased the accommodative ability of participants, all three parameters i.e. NPC, degree of exophoria and PFV were improved. Our data confirm that smartphone based exercises is an effective and good alternative for conventional exercises to improve binocular function in young adults who are spending a lot of time in these hand held android devices and having convergence insufficiency

Convergence insufficiency are often extremely troublesome for patients especially at near work.[4] In this study all patients were symptomatic and symptoms vary from mild to severe.The disorder is reported to be common in young adults because of increased visual demands of reading and school and college work.[5] All participants in this study is young adults. The prevalence of convergence insufficiency has been reported to be approximately 3-5%. In our study the prevalence is 26/150 (17.33%) because we have taken only patients with asthenopic symptoms.

Convergence exercises (ie, orthoptics, vision therapy) and/or base-in prisms are the mainstays of treatment of convergence insufficiency. [6]stereogram cards may be used by an orthoptist or a vision therapist to improve fusional convergence. New, affordable computerized fusionalvergence training programs (eg, Computer Orthoptics) are also available. These self-paced programs can be used on a personal computer in the patient’s home.

A paper by Scheiman et al [7] in a review of 3 multicenter randomized clinical trials, while recognizing some limitations of the summarized studies, reported that office-based vision therapy provides superior results as a treatment modality versus specific home-based therapies (pencil push-up and some computer-based therapy) or placebo. A study done  through the Pediatric Eye Disease Investigator Group (PEDIG) regarding the treatment of symptomatic convergence insufficiency to determine the effectiveness of active home-based computer (HB-C) vergence/accommodative therapy versus placebo home-based computer (HB-PU) vergence/accommodative therapy for the treatment of symptomatic convergence insufficiency in children aged 9-18 years. At the 12-week primary outcome examination, 16 of 69 participants (23%, 95% CI: 14–35%) in the HB-C group, 15 of 69 participants (22%, 95% CI: 13–33%) in the HB-PU group, and 5 of 31 participants (16%, 95% CI: 5–34%) in the HB-P group achieved a successful outcome.[8]

There is no study on smartphone based exercise till date so we have decided to study the home based smartphone exercise in symptomatic convergence insufficiency. In our study  near point of convergence improved by 2.89+_1.08 cm, positive fusion vergence by -10.2+_3.25pd and near phoria by 3.13+_0.32pd (p<0.001). All patients were symptomatically free at 12 weeks follow up. Our result is similar to the study done by Jang  et al on school children to see the effectiveness of vision therapy.[9]

We have also modified the glass prescription to ensure the active use of participants own accommodation to control his/her phoria. Rules which we have followed: 1- Any refractive error resulting in reduced vision should be corrected to improve fusion 2- Minor amount of myopia should also be corrected 3- Hypermetropia with normal vision does not warrant a prescription, as it reduces the need to converge. 4- High hypermetropia with reduced vision should be prescribed but under corrected. Our study also focuses on the need of basic rule of prescribing glasses to take into account associated conditions like convergence insufficiency and fusion weakness and accommodative elements prior to prescribing glasses before asking for orthoptic exercises.

Conclusion

In conclusion, the current study  emphasizesthe efficacy of smartphone based fusion exercises and prescription of glasses with modification after considering the phoria component in management of symptomatic convergence and fusion insufficiency. A home based smartphone application  program appears to be the treatment of choice forreducing CI symptoms in current mobile era. Indeed, this novel newly designed approach for CI improvessymptoms by reducing NPC and degree of exophoriaand increasing PFV. 

References

  1. Daftari A, Alvarez TL, Chua F, Demarco R, Ciuffreda K. The dynamics of convergence insufficiency.Bioengineering Conference 2003, IEEE 29th annual, Proceedings; 2003.pp. 41‑42.
  2. Mcgregor ML. Convergence Insufficiency and vision therapy. PediatrClin N Am 2014;61:621‑630.
  3. Scheiman M, Wick B. Clinical management of binocular vision. 2nd ed. USA: Lippincott‑Raven; 2002. pp. 224.
  4. Danchaivijitr C, Kennard C. Diplopia and eye movement disorders.J NeurolNeurosurg Psychiatry. 2004 Dec. 75 Suppl 4:iv24-31.
  5. Clark TY, Clark RA. Convergence Insufficiency Symptom Survey Scores for Reading Versus Other Near Visual Activities in School-Age Children. Am J Ophthalmol. 2015 Aug
  6. – Sreenivasan V, Bobier WR. Increased onset of vergence adaptation reduces excessive accommodation during the orthoptic treatment of convergence insufficiency. Vision Res. 2015 Jun. 111 (Pt A):105-13.
  7. – Scheiman M, Rouse M, Kulp MT, Cotter S, Hertle R, Mitchell GL. Treatment of convergence insufficiency in childhood: a current perspective. Optom Vis Sci. 2009 May. 86(5):420-
  8. Pediatric Eye Disease Investigator Group. Effectiveness of Home-Based Therapy for Symptomatic Convergence Insufficiency. Optometry & Vision Science: December 2016 – Volume 93 – Issue 12 – p 1457–1465
  9. Jang JU, Jang JY, Tai-hyung K, Moon HW. Effectiveness of vision therapy in school children with symptomatic convergence insufficiency. J Ophthalmic Vis Res 2017;12:187-92.

 

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