Sudanese Journal of Ophthalmology

ORIGINAL ARTICLE
Year
: 2017  |  Volume : 9  |  Issue : 1  |  Page : 5--9

Efficacy of home-based vision therapy for convergence insufficiency in secondary schools' students


Layali Ibrahim Hassan1, Samira Mohamed Ibrahim2, Mustafa Abdu3,  
1 Department of Ophthalmology, Dibba Hospital, Dibba, Sultanate of Oman
2 Department of Ophthalmology, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
3 Department of Contact Lenses, Faculty of Optometry and Visual Sciences, Al-Neelain University, Khartoum, Sudan

Correspondence Address:
Layali Ibrahim Hassan
Department of Ophthalmology, Dibba Hospital, P.O. Box 9, P.C 800, Dibba, Sultanate of Oman

Abstract

Background: Convergence insufficiency (CI) is one of the most common causes of ocular discomfort among students that it may have a negative effect on the student's school performance. Although various treatments are prescribed for patients with CI, there is a lack of studies regarding the most effective treatment. Aim: The aim of this study is to determine the efficacy of four home-based vision therapy (VT) techniques in the treatment of symptomatic CI. Materials and Methods: A Convergence Insufficiency Treatment Trial was conducted in Central Khartoum North (Central Bahri) in Sudan. A total of 273 students with mean age of 15.5 ± 2.5 years with symptomatic CI were assigned to one of the four TV groups: Pencil push-Up (n = 66), Cat card (n = 65), Brock string (n = 66), Dot card (n = 66) against placebo control group (n = 66). Data were collected using three outcome measurements: Convergence Insufficiency Symptom Survey score, Near Point of Convergence (NPC), and Positive Fusional Vergence (PFV) at near. Data were collected at baseline, after 3 weeks and at the end 6 weeks of treatment. The participants were advised to do this exercise at home 10 min per day, for 5 days a week for 6 weeks. Results: After 6 weeks of treatment, Dot card therapy group showed the best result in eliminating CI symptoms score by the mean value of 13.59 points (P < 0.001). Pencil push-up therapy group showed the best result in improving NPC by the mean value of 5.60 cm (P < 0.001). However, Cat card therapy group showed the best result in improving PFV by mean value of 7.32 PD (P < 0.001). Conclusions: All four home-based VT techniques were significantly reduced symptoms and improved NPC and PFV. The home-based VT techniques are effective option for treating symptomatic CI. There is no unified treatment suitable for all patients with CI. Therapist should deal with each patient separately.



How to cite this article:
Hassan LI, Ibrahim SM, Abdu M. Efficacy of home-based vision therapy for convergence insufficiency in secondary schools' students.Sudanese J Ophthalmol 2017;9:5-9


How to cite this URL:
Hassan LI, Ibrahim SM, Abdu M. Efficacy of home-based vision therapy for convergence insufficiency in secondary schools' students. Sudanese J Ophthalmol [serial online] 2017 [cited 2017 Dec 13 ];9:5-9
Available from: http://www.sjopthal.net/text.asp?2017/9/1/5/215104


Full Text

 Introduction



Convergence insufficiency (CI) is one of the most common causes of ocular discomfort among students that it may have a negative effect on the student's school performance.[1] Symptoms of CI include eyestrain, headaches, blurred vision, diplopia, difficulty concentrating, movement of print while reading, and lack of comprehension after reading or performing near activities.[2],[3],[4] The various treatments of CI can be mainly grouped into two categories: home-based and office-based vision therapy (VT).[3] Recent studies have suggested that home-based VT is the most commonly prescribed treatment for symptomatic CI.[4] Home-based VT is simple techniques, prescribed in short period, requires fewer office visits, requires fewer follow-up visits, requires no specialized equipment and may be less costly than office-based therapy.[5]

Although various treatments are prescribed for patients with CI, there is a lack of studies regarding the most effective treatment, and there are only a few studies which compare different modalities of treatment. There are significant differences which exist in the time commitment for the patient, dosage, mode of administration, number of office visits, cost, and complexity of the treatment. It is unknown, however, whether these differences affect the outcome of treatment. However, there is a lack of information in Sudan, which related to comparison between different modalities of treatment.

This study is aimed to evaluate four home-based VT techniques used for treatment of CI in secondary schools' students in central Khartoum North Locality in Sudan.

 Materials and Methods



In this study, a total of 273 students with mean age of 15.5 ± 2.5 years (range 13–18 years) with symptomatic CI from ten public secondary schools located in Central of Khartoum North Locality in Sudan were recruited.

Eligibility criteria included CI symptomatic patients with best-corrected visual acuity of ≥6/9 in each eye at distance, exophoria at near at least 4 Δ greater than at far, receded Near Point of Convergence (NPC) of ≥7 cm break, insufficient Positive Fusional Vergence (PFV) at near. ≤15 base-out prism, and willingness to participate in the study. Exclusion criteria included patients with previous VT, patients with a history of strabismus (e.g., pattern strabismus), hyperopia, amblyopia, suppression, or uncorrected refractive errors. Patients with systemic diseases or use of medications might influence accommodation, vergence, and ocular motility.

Written consent letter with detailed information about the study was obtained from the Ministry of Higher Education and Scientific Research. Another written consent was obtained from the parents before being involved in the study. Main outcome measures were divided into primary and secondary outcome measures. Primary outcome measure was Convergence Insufficiency Symptoms Survey (CISS) score [Table 1]. Secondary outcome measures were the NPC and PFV at near. In CISS, each symptom question was weighted as 0, 1, 2, 3, and 4 as they reported never, infrequently, sometimes, fairly often, and always, respectively. Symptom score was derived by adding the total symptom weight. Visual acuity was taken with 3 m Snellen chart (Haag-Streit, UK) with maximum contrast both uncorrected and the best most recently prescribed glasses. NPC was measured with RAF binocular gauge (Haag-Streit, UK), PFV, and deviation of the eyes if any were measured with horizontal prism bar (Haag-Streit, UK). NPC value more than 8 cm, PFV of < 25 PD, and CISS of more than 21 were considered to have CI and only these patients were continued for the study. After the initial measurement of mentioned parameters, the participants were assigned to one of the four treatment groups: Pencil push-Up, Cat card, Brock string, Dot card or placebo control group. The participants were given VT training. The dose of VT for all treatment groups was the following: the exercises were carried out at home and for 10 min per day, for 5 days per week for 6 weeks. The written instruction papers and follow-up tables given to each participant to insure doing exercises perfectly. Treatment compliance procedures were also done to insure patients' compliance. Again NPC, PFV and CISS score were recorded at the 6th week. According to Borsting et al., “the success or failure of vision treatment is determined by changes in clinical signs as well as patient symptoms.”[3]{Table 1}

 Results



Out of 329 students included in the study, 273 (83%) students completed their 6 weeks of treatment with drop-out rate of 56 (17.02%) students. The participants were distributed equally between four treatment groups [Figure 1]. There were 173 (52.6%) males and 156 (47.4%) females. The demographic characteristics of participants are illustrated in [Table 2].{Figure 1}{Table 2}

With regard to CISS [Table 1], and using statistical paired sample t-test, Dot card therapy group showed the most effective method in elimination of symptoms of CI (P < 0.001) [Figure 2]. The mean of CI symptom score in Dot card therapy group at first visit was 29.93 ± 11.44 points compared with 16.34 ± 11.81 points after 6 weeks of treatment. The improvement in CI symptom score was calculated to be 13.59 points. Evaluation using CISS score showed that Dot card therapy recorded higher improvement compared to other treatment groups (the mean change was 13.59 points) followed by Cat card therapy (12.90 points), Pencil push-up therapy (12.38 points), and Brock string therapy (11.60 points), respectively [Table 3].{Figure 2}{Table 3}

With regard to NPC, Pencil push-up therapy showed the most effective method in improving the NPC (P < 0.001) using statistical paired sample t-test [Figure 3]. The mean of NPC in the Pencil push-up therapy group at first visit was 20.10 ± 8.22 cm compared with 14.50 ± 5.95 cm after 6 weeks of treatment. The improvement in NPC was calculated to be 5.60 cm. Evaluation using NPC showed that the marked improvement of NPC found in Pencil push-up therapy recorded compared to other treatment groups (the mean change was 5.60 cm) followed by Cat card therapy (3.64 cm), Dot card therapy (3.61 cm), and Brock string therapy (1.07 cm), respectively [Table 3].{Figure 3}

With regard to PFV, and using statistical paired sample t-test, Cat card therapy was the most effective method in improving PFV (P < 0.001) [Figure 4]. The mean of PFV in the Cat card therapy group at first visit was 6.98 ± 3.97 PD compared with 14.30 ± 5.38 PD after 6 weeks of treatment. The improvement in PFV was calculated to be 7.32 PD. Evaluation using PFV showed that Cat card therapy recorded higher improvement compared to other treatment groups (the mean change was 7.32 PD) followed by Dot card therapy (6.58 PD), Pencil push-up therapy (6.24 PD), and Brock string therapy (2.98 PD), respectively [Table 3].{Figure 4}

 Discussion



This study aimed to determine whether significant clinical changes would be observed between clinical findings after 6 weeks of repetitive four different techniques of home-based VT groups in students with CI compared to placebo controls.

The mean symptoms score CISS showed improvement in symptoms score by the mean value of 12.62 points. Hence, it shows that the VT techniques are beneficial with CI. Findings from the current study contradicted with that found in other studies carried out by Scheiman et al. in USA.[6],[7] They found that symptom score can be improved by office-based VT only but not by home-based VT.

The mean NPC at first visit was 17.55 ± 6.48 cm which decreased to 13.66 ± 5.15 cm after 6 weeks of treatment. These finding showed that the VT techniques are beneficial with CI. Similar results were found in a study reported by Kim and Chunin the Korean population.[8] The initial mean NPC of 36.3 cm was improved to mean NPC of 14.4 cm after 12 weeks of treatment. Gallaway et al. in their pilot study also found that NPC improved in almost all patients with Pencil push-up therapy.[9] In a recent multicenter, placebo-controlled, randomized Convergence Insufficiency Treatment Trial study carried out by Convergence Insufficiency Treatment Trial study group reported that NPC can be improved only by office-based VT not improve significantly with home-based VT in CI patients.[10]

In the present study, mean of PFV showed improvement of 6.56 PD and it clearly showed that the VT is efficacious in improving fusional vergence. These findings were similar to that reported by other studies.[8],[9] However, the findings of Scheiman et al.[6],[7],[10] were totally different from the current study. They found that home-based VT can not improve the PFV significantly.

By comparison, office-based VT for CI uses more specialized equipment and it is not surprising that office-based VT techniques are robust and quickly effective. While in-office VT is the ideal treatment of choice for symptomatic CI, it is not always practical, may be too expensive, needs specialized equipment necessary for a full course and may not be locally available. In these instances, a viable alternative would be to prescribe home-based VT.

Finally, the current study showed that the home-based VT is an effective method for treating CI among Sudanese secondary schools' students. There is clinical significant improvement on binocular functions and elimination of symptoms. In the authors' opinion, there is no unified therapy suitable for all patients. Therapist should deal with individual patients as separately and put the therapy plan for each patient according to the patient's needs and according to specific signs and symptoms.

 Conclusion



Home based VT techniques are effective option for treating symptomatic CI. There is no unified treatment suitable for all patients with CI. Therapist should deal with each patient separately.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1von Noorden GK, Campos EC. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed. St. Louis: Mosby; 2002. p. 502-3.
2Daum KM. Convergence insufficiency. Am J Optom Physiol Opt 1984;61:16-22.
3Borsting EJ, Rouse MW, Mitchell GL, Scheiman M, Cotter SA, Cooper J, et al. Validity and reliability of the revised convergence insufficiency symptom survey in children aged 9 to 18 years. Optom Vis Sci 2003;80:832-8.
4Scheiman M, Cooper J, Mitchell GL, de LP, Cotter S, Borsting E, et al. A survey of treatment modalities for convergence insufficiency. Optom Vis Sci 2002;79:151-7.
5Pediatric Eye Disease Investigator Group. Home-Based Therapy for Symptomatic Convergence Insufficiency in Children: A Randomized Clinical Trial. Optom Vis Sci 2016;93:1457-1465.
6Scheiman M, Mitchell GL, Cotter S, Cooper J, Kulp M, Rouse M, et al. A randomized clinical trial of treatments for convergence insufficiency in children. Arch Ophthalmol 2005;123:14-24.
7Scheiman M, Mitchell GL, Cotter S, Kulp MT, Cooper J, Rouse M, et al. A randomized clinical trial of vision therapy/orthoptics versus pencil pushups for the treatment of convergence insufficiency in young adults. Optom Vis Sci 2005;82:583-95.
8Kim KM, Chun BY. Effectiveness of home-based pencil push-ups (HBPP) for patients with symptomatic convergence insufficiency. Korean J Ophthalmol 2011;25:185-8.
9Gallaway M, Scheiman M, Malhotra K. The effectiveness of pencil pushups treatment for convergence insufficiency: A pilot study. Optom Vis Sci 2002;79:265-7.
10Convergence Insufficiency Treatment Trial Study Group. Randomized clinical trial of treatments for symptomatic convergence insufficiency in children. Arch Ophthalmol 2008;126:1336-49.