Long-term effectiveness of vision therapy for symptomatic convergence insufficiency in children

Abstract

Objective To study the long-term effectiveness of vision therapy for children who were cured after treatment for convergence insufficiency (CI) by assessing the symptoms and signs. Methods Forty patients aged 7 to 18 years who were asymptomatic after a 12-week therapy program for CI in optometric center of Tianjin Eye Hospital were recruited in this prospective study. These patients were followed up at 1 week, 3 months, and 6 months after completion of the 12-week office-based visual therapy and were examined for clinical symptom scores (CISS) and visual function parameters that near point of convergence (NPC), near positive fusional vergence (PFV) and accommodative amplitude (AA). The results were analyzed with repeated ANOVA, pearson correlation analysis and independent-samples t-tests. Results The percentage who remained asymptomatic with no clinical signs after 3 months and 6 months was 85%(34/40) and 68%(26/38), respectively. There were no significant changes in the CISS, NPC or near PFV during the half-year follow-up period (F=2.852,1.995, 3.006, P>0.05). But there were significant differences in the NPC, CISS and AA before 12-week therapy program between the patients who had symptoms or clinical signs and those who were normal (Z=-3.212, P<0.01; Z=-2.461, P<0.05; t=2.264, P<0.05). NPC, CISS and AA before 12-week therapy program showed a significant correlation to CISS at 6 months after treatment (r=0.420, P<0.01; r=0.473, P<0.01; r=-0.361, P<0.05). Conclusion Most children who were cured after a 12-week office-based vision therapy program for CI maintained their improvements in symptoms and signs for at least half a year after discontinuing treatment. This may be related to the near NPC and CISS as well as the AA. Key words: Symptomatic convergence insufficiency; Office-based vision therapy; Treatment outcome; Near point convergence (NPC)