Methods: Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects.
Results: Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated.
Conclusions: Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes.
Aziz S, Cleary M, Stewart HK, Weir CR "Are orthoptic exercises an effective treatment for convergence and fusion deficiencies?" Strabismus. Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, UK. 14(4):183-9: 2006.
Purpose: To investigate whether orthoptic exercises are an effective way to influence the near point of convergence, fusion range and asthenopic symptoms.
Methods: Seventy-eight patients met the inclusion criteria of visual acuity 6/9 or better, no history of orthoptic treatment, squint surgery or Meares Irlen syndrome/dyslexia. Information was collected from case records related to diagnosis, near point of convergence, fusion range, prism and cover test measurements and symptoms. Type, duration and frequency of exercises were also recorded. Non-parametric statistics were applied.
Conclusions: Orthoptic exercises are an effective means of reducing symptoms in patients with convergence insufficiency and decompensating exophoria, and appear to target the proximal and fusional components of convergence. Their role in esophoria is unclear and needs further study.
Borsting E; Rouse MW; De Land PN, "Prospective comparison of convergence insufficiency and normal binocular children on CIRS symptom surveys. Convergence Insufficiency and Reading Study (CIRS) group." Optom Vis Sci. 76(4):221-8, 1999.
Cooper J, Duckman R "Convergence insufficiency: incidence, diagnosis and treatment." J Amer O ptom Assoc, (49): 673-680, 1978.
Cooper J. "Review of computerized orthoptics with specific regard to convergence insufficiency." Am J Optom Physiol Opt, 65:448-54, 1988.
Petrunak JL. "The treatment of convergence insufficiency." American Orthoptic Journal, 49:12-16, 1999.
Rouse MW, Borsting E, Hyman L, Hussein M, Cotter SA, Flynn M, Scheiman M, Gallaway M, De Land PN, "Frequency of Convergence Insufficiency Among Fifth and Sixth Graders." The Convergence Insufficiency and Reading Study (CIRS) group. Optom Vis Sci. 76(9):643-9, 1999.
Rouse MW, Hyman L, Hussein M, Solan H. "Frequency of convergence insufficiency in optometry clinic settings. Convergence Insufficiency and Reading Study (CIRS) Group." Optom Vis Sci 1998 Feb;75(2):88-96
Rouse M, Borsting E, Mitchell GL, Kulp MT, Scheiman M, Amster D, Coulter R, Fecho G, Gallaway M; The CITT Study Group. "Academic Behaviors in children with convergence insufficiency with and without parent-reported ADHD." Optom Vis. Sci. 2009.
Scheiman, M; Cotter, S; Rouse, M; Mitchell, G L; Kulp, M; Cooper, J; Borsting, E; et al (CITT). "A Randomized Clinical Trial of Vision Therapy/Orthoptics versus Pencil Pushups for the Treatment of Convergence Insufficiency in Young Adults." Optometry and Vision Science. 2005.
Methods: Seventy-nine patients who were asymptomatic after a 12-week therapy program for convergence insufficiency were followed for 1 year [33/60 in office-based vergence/accommodative therapy (OBVAT), 18/54 in home-based pencil push-ups (HBPP), 12/57 in home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), and 16/54 in office-based placebo therapy (OBPT)]. Symptoms and clinical signs were measured 6 months and 1 year after completion of the 12-week therapy program. The primary outcome measure was the mean change on the Convergence Insufficiency Symptom Survey (CISS). Secondary outcome measures were near point of convergence, positive fusional vergence at near, and proportions of patients who remained asymptomatic or who were classified as successful or improved based on a composite measure of CISS, near point of convergence, and positive fusional vergence.
Conclusions: Most children aged 9 to 17 years who were asymptomatic after a 12-week treatment program of OBVAT for convergence insufficiency maintained their improvements in symptoms and signs for at least 1 year after discontinuing treatment. Although the sample sizes for the home-based and placebo groups were small, our data suggest that a similar outcome can be expected for children who were asymptomatic after treatment with HBPP or HBCVAT+.
Scheiman M; Mitchell GL; Cotter S; Kulp M; et al (CITT). "Vision therapy/orthoptics for symptomatic convergence insufficiency in children: treatment kinetics." Optom. Vis. Sci. June 10: 2010.
Methods: In a randomized clinical trial, 221 children aged 9 to 17 years with symptomatic CI were assigned to home-based pencil push-ups (HBPP), home-based computer vergence/accommodative therapy and pencil push-ups (HBCVAT+), office-based vergence/accommodative therapy with home reinforcement (OBVAT), or office-based placebo therapy with home reinforcement (OBPT). Symptoms and signs were measured after 4, 8, and 12 weeks of treatment. The outcome measures were the mean CI Symptom Survey (CISS), near point of convergence (NPC), positive fusional vergence (PFV), and proportions of patients who were classified as successful or improved based on a composite measure of CISS, NPC, and PFV.
Results: Only the OBVAT group showed significant improvements in symptoms between each visit (p < 0.001). Between weeks 8 and 12, all groups showed a significant improvement in symptoms. Between-group differences were apparent by week 8 (p = 0.037) with the fewest symptoms in the OBVAT group. For each group, the greatest improvements in NPC and PFV were achieved during the first 4 weeks. Differences between groups became apparent by week 4 (p < 0.001), with the greatest improvements in NPC and PFV in the OBVAT group. Only the OBVAT group continued to show significant improvements in PFV at weeks 8 and 12. The percentage of patients classified as "successful" or "improved" based on our composite measure increased in all groups at each visit.
Conclusions: The rate of improvement is more rapid for clinical signs (NPC and PFV) than for symptoms in children undergoing treatment for CI. OBVAT results in a more rapid improvement in symptoms, NPC and PFV, and a greater percentage of patients reaching pre-determined criteria of success when compared with HBPP, HBCVAT+, or OBPT.
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.