Results for Accommodative Amplitude
Within-Group Comparisons: Change in Accommodative Amplitude between Examinations by Treatment Group
The mean increase in accommodative amplitude (range of 4.5 to 4.7 D) from baseline to week 4 for the active therapy groups was significantly greater than zero (p-values <0.0001), whereas the change in the placebo group was not (1.8 D, p = 0.057; Table 3). Between weeks 4 and 8, only the OBVAT group showed a significant improvement in accommodative amplitude (2.8 D, p < 0.001), whereas in the 8- to 12-week interval, both the OBVAT and HBCVAT+ groups showed significant improvements (2.0 D, p = 0.02 and 2.0 D, p = 0.037, respectively).
Increased Accommodative Amplitude: Vision Therapy/ Orthoptics Therapy Compared with Placebo Therapy
Significant treatment group differences in mean accommodative amplitude were present only at weeks 8 and 12 (p < 0.001 and p < 0.0001, respectively; Fig. 1). At the 8-week visit, the mean accommodative amplitude of the OBVAT group was approximately 5 D greater than that of the placebo group (p < 0.0001), with the difference increasing to more than 7 D at week 12 (p < 0.0001; Table 1). The improvement in accommodative amplitude for the HBCVAT+ group was significantly different from that of the placebo group only at week 12 (difference = 4.3 D, p = 0.002), while the HBPP group showed a significantly greater mean amplitude (difference = 3.6 D) at both weeks 8 and 12 (p = 0.009 and p = 0.010, respectively) when compared with placebo.
At study completion, the mean increases in accommodative amplitude (9.3 D for OBVAT, 6.8 D for HBCVAT+, and 5.9 D for HBPP) were significantly greater than the 2.4 D gain found for the placebo group (p-values ≤ 0.01; Table 1; Fig. 2). A decreased amplitude of accommodation was no longer present in 91.4% (32/35) of the patients in OBVAT, 79.3% (23/29) in HBCVAT+, and 74.1% (20/27) in HBPP, compared with 35.7% (10/28) of those assigned to placebo treatment (p < 0.003).
Of the patients who no longer had a decreased amplitude of accommodation at treatment completion (n = 85) and did not undergo subsequent treatment during the 1-year follow-up period (n = 44), the mean decrease in accommodative amplitude was 1.4 D (p = 0.044). A recurrence of decreased accommodative amplitude occurred in 11% (5/44) (4 of 12 in HBPP, 1 of 21 in OBVAT, 0 of 9 in HBCVAT+ and 0 of 2 in placebo).
Within-Group Comparisons: Change in Accommodative Facility between Examinations by Treatment Group
The OBVAT group showed significant improvement in accommodative facility (4.4 cpm, p < 0.0001) from baseline to 4 weeks and between 4 and 8 weeks (4.4 cpm, p < 0.0001), with no significant improvement between 8 and 12 weeks (0.8 cpm, p = 0.39; Fig. 3). The HBCVAT+ group showed significant improvements from baseline to week 4 (3.3 cpm, p < 0.0001) and showed smaller but statistically significant improvements of approximately 2 cpm between weeks 4 to 8 (p = 0.002) and 8 to 12 (p = 0.029). The HBPP group only showed significant gains between weeks 4 and 8 (2.1 cpm, p = 0.004). The placebo group showed significant improvements only at week 4 (2.8 cpm, p = 0.002).
Active Vision Therapy/Orthoptic Therapies Compared with Placebo Therapy after 4, 8, and 12 weeks of Treatment
There was no difference in mean accommodative facility between treatment groups at week 4 (p = 0.30); however, significant differences were found at weeks 8 (p = 0.010) and 12 (p = 0.037) (Fig. 3; Table 2). Compared with the placebo group, only the OBVAT group's mean accommodative facility was significantly better at the 8-week visit (mean difference of 4.7 cpm; p = 0.003) and the 12-week visit (mean difference of 3.9 cpm; p = 0.016).
At treatment completion, accommodative facility increased by 9.5 cpm in the OBVAT group, 7.0 cpm in the HBCVAT+ group, 4.9 cpm in the HBPP group, and 5.5 cpm in the placebo group (Table 2). Only the OBVAT group showed a significantly greater improvement in accommodative facility than the placebo group (p = 0.016) (Fig. 4).
After 12 weeks of treatment, decreased accommodative facility was no longer present in 87% (20/23) of OBVAT patients, 70% (21/30) of the HBCVAT+ patients, and 63.6% (14/22) of the HBPP patients, when compared with 57.7% (15/26) of those assigned to placebo treatment (p = 0.15).
Among the patients who did not have reduced accommodative facility at week 12 (n = 70) and performed no other treatments during subsequent 1-year follow-up period (32, 46%) there was a small, non-significant decrease in facility found at the 12-mo follow-up visit (−0.7 cpm, range −12.0 to 9.5 cpm, p = 0.41). Of these 32 patients, 4 (12.5%) regressed sufficiently to be diagnosed with deficient accommodative facility (1/11 OBVAT, 2/7 HBPP, 0/8 HBCVAT+, and 1/6 OBPT).
There were six vision- or eye-related events among the 221 patients enrolled in the study. All were unexpected and further evaluations determined that all six were not serious and unrelated to the study treatment.
We compared the effectiveness of OBVAT, HBCVAT+, and HBPP to office-based placebo therapy for improving accommodative amplitude and facility in children with both symptomatic CI and accommodative dysfunction who were enrolled in the CITT. Although the primary objective of the study was the comparison of the effectiveness of active treatments for symptomatic CI, accommodative function was measured at baseline and at all subsequent study visits, and each active therapy program included accommodative therapy. This allowed us to evaluate the kinetics of change in accommodative function and the effectiveness of the three therapy modalities in improving accommodative amplitude and facility.
All three of the vision therapy/orthoptic treatments were significantly more effective than placebo therapy for improving accommodative amplitude in patients with decreased accommodative amplitude while only OBVAT was significantly more effective than placebo therapy in improving accommodative facility in patients. In addition, at the end of the 12-week treatment period, significantly fewer patients had a decreased amplitude of accommodation or subnormal accommodative facility in the active therapy groups compared with the placebo. Finally, the gains demonstrated at 12 weeks were still present in the majority (>87%) of patients after 1-year off treatment.
Although all three active treatment modalities included some form of accommodative therapy, there were differences in the type of the accommodative procedure, format of the therapy (monocular, biocular, and binocular), and time spent performing the therapy. Accommodative therapy for accommodative insufficiency and infacility traditionally includes procedures designed to increase both the amplitude of accommodation and the dynamics of the accommodative response.5 The objectives of the latter type of accommodative therapy, also referred to as accommodative facility therapy, are to decrease the latency and increase the speed of the accommodative response. Procedures designed to increase the amplitude of accommodation use an accommodative stimulus that is increased in a slow, gradual manner while procedures used to improve the dynamics of the accommodative response alter the accommodative stimulus in large discrete steps. Generally, accommodative amplitude procedures are emphasized initially and once the amplitude normalizes, facility procedures are introduced. In addition, accommodative therapy is generally sequenced so that accommodative function is improved and equalized in each eye monocularly before beginning binocular accommodative therapy.5 Of the three active treatments used in this study, only OBVAT incorporated both accommodative amplitude and facility procedures and used a monocular to binocular therapy sequence. The OBVAT treatment sequence used monocular accommodative amplitude and facility techniques during the first 8 week, and binocular accommodative facility techniques between weeks 8 and 12. The HBCVAT+ group performed biocular (both eyes open, but no fusion) accommodative facility therapy for the entire treatment period. Although there was no specific accommodative therapy procedure per se for the HBPP group, pencil push-up therapy involved maintaining clarity as the accommodative target was moved toward the child's eyes and thus can be considered a binocular accommodative amplitude procedure. These differences in therapy may explain some of the apparent differences in effectiveness.
In terms of the kinetics of change in accommodative amplitude during the 12-week treatment program, there was a significant improvement in amplitude from baseline to week 4 in all groups except the placebo group but only the OBVAT group demonstrated continued improvements between weeks 4 and 12. For accommodative facility, most improvements occurred during the first 8 week of therapy for all three active therapy groups. The treatment kinetic data reported herein provide guidance regarding the timing of follow-up visits. Because the largest changes in both accommodative amplitude and facility occurred by 4 weeks for all three treatment groups, 4 weeks appears to be an appropriate time for a progress evaluation. Absence of any improvement after 4 weeks of treatment might suggest poor adherence to therapy or cast doubt on the accuracy of the diagnosis.
Although previous studies have reported that active vision therapy is an effective treatment for accommodative dysfunction, these studies suffer from a variety of design limitations including retrospective design,10,19,20 small sample size,12,20,32 lack of a placebo group,10,19,20 and use of unmasked examiners.10,12,19,20,32 In addition, some of the studies used adult patients17,19 and only investigated home-based therapy.12,19 Thus, there are no other data from well-designed, randomized clinical trials showing the effectiveness of vision therapy/orthoptics compared with a placebo control group for accommodative dysfunction in children.
The strengths of our study include its prospective design, adequate sample size, randomization of patients, having a placebo control for the OBVAT group, evidence of successful masking of examiners and patients in the OBVAT and OBPT groups, and outstanding follow-up.22 Because the study was not designed specifically to investigate the effectiveness of therapy for accommodative function, one might argue that the data do not demonstrate whether office- or home-base therapy are effective for patients with accommodative dysfunction alone. However, because the therapy procedures that would be prescribed for children with accommodation dysfunction alone would actually be more extensive, there is good reason to believe that the results of this study may underestimate the potential for success. Only approximately half of the subjects could be included in the analyses of long-term follow-up because subjects had to be both asymptomatic and have normal accommodative function. We are also unable to comment about the effect of therapy on symptoms related to accommodative problems because the patients all had CI as well. Because a natural history group was not included in the study, it is unknown if the small and generally nonsignificant improvements in the placebo group were due to placebo effect or regression to the mean. We can conclude, however, that meaningful and significantly greater improvements in accommodative amplitude and facility can be achieved using vision therapy/orthoptics and that the gains cannot be attributed to the placebo effect. Furthermore, these gains are maintained for a least a year in the majority of subjects. Future studies should consider including objective measures of accommodative function and additional studies are necessary to compare office-based vs. home-based treatments specifically designed to address accommodative dysfunction. Our data demonstrate improvement of accommodative function in children with poor accommodative amplitudes or facility and should be the impetus for a new randomized clinical trial studying the effectiveness of various therapies for the treatment of symptomatic accommodative dysfunction in children.
In this first, large-scale randomized clinical trial in children with CI and accommodative dysfunction, vision therapy/orthoptics was effective for improving decreased accommodative amplitude and accommodative facility. Further study is required to determine the most effective treatment approach (office-based vs. home-based), most effective therapy procedures, effect of accommodative therapy on symptoms in patients with symptomatic accommodative dysfunction alone, and the optimum duration of therapy.
The Convergence Insufficiency Treatment Trial Study Group
Sites are listed in order of the number of patients enrolled in the study with the number of patients enrolled is listed in parentheses preceded by the site name and location. Personnel are listed as (PI) for principal investigator, (SC) for coordinator, (E) for examiner, and (VT) for therapist.
Bascom Palmer Eye Institute (35)
Susanna Tamkins, OD (PI); Hilda Capo, MD (E); Mark Dunbar, OD (E); Craig McKeown, MD (CO-PI); Arlanna Moshfeghi, MD (E); Kathryn Nelson, OD (E); Vicky Fischer, OD (VT); Adam Perlman, OD (VT); Ronda Singh, OD (VT); Eva Olivares (SC); Ana Rosa (SC); Nidia Rosado (SC); Elias Silverman (SC)
SUNY College of Optometry (28)
Jeffrey Cooper, MS, OD (PI); Audra Steiner, OD (E, Co-PI); Marta Brunelli (VT); Stacy Friedman, OD (VT); Steven Ritter, OD (E); Lily Zhu, OD (E); Lyndon Wong, OD (E); Ida Chung, OD (E); Kaity Colon (SC)
UAB School of Optometry (28)
Kristine Hopkins, OD (PI); Marcela Frazier, OD (E); Janene Sims, OD (E); Marsha Swanson, OD (E); Katherine Weise, OD (E); Adrienne Broadfoot, MS, OTR/L (VT, SC); Michelle Anderson, OD (VT); Catherine Baldwin (SC)
NOVA Southeastern University (27)
Rachel Coulter, OD (PI); Deborah Amster, OD (E); Gregory Fecho, OD (E); Tanya Mahaphon, OD (E); Jacqueline Rodena, OD (E); Mary Bartuccio, OD (VT); Yin Tea, OD (VT); Annette Bade, OD (SC)
Pennsylvania College of Optometry (25)
Michael Gallaway, OD (PI); Brandy Scombordi, OD (E); Mark Boas, OD (VT); Tomohiko Yamada, OD (VT); Ryan Langan (SC), Ruth Shoge, OD (E); Lily Zhu, OD (E)
The Ohio State University College of Optometry (24)
Marjean Kulp, OD, MS (PI); Michelle Buckland, OD, MS (E); Michael Earley, OD, PhD (E); Gina Gabriel, OD, MS (E); Aaron Zimmerman, OD, MS (E); Kathleen Reuter, OD (VT); Andrew Toole, OD, PhD (VT); Molly Biddle, MEd (SC); Nancy Stevens, MS, RD, LD (SC)
Southern California College of Optometry (23)
Susan Cotter, OD, MS (PI); Eric Borsting, OD, MS (E); Michael Rouse, OD, MS, (E); Carmen Barnhardt, OD, MS (VT); Raymond Chu, OD (VT); Susan Parker (SC); Rebecca Bridgeford (SC); Jamie Morris (SC); Javier Villalobos (SC)
University of CA San Diego: Ratner Children's Eye Center (17)
David Granet, MD (PI); Lara Hustana, OD (E); Shira Robbins, MD (E); Erica Castro (VT); Cintia Gomi, MD (SC)
Mayo Clinic (14)
Brian G. Mohney, MD (PI); Jonathan Holmes, MD (E); Melissa Rice, OD (VT); Virginia Karlsson, BS, CO (VT); Becky Nielsen (SC); Jan Sease, COMT/BS (SC); Tracee Shevlin (SC)
CITT Study Chair
Mitchell Scheiman, OD (Study Chair); Karen Pollack (Study Coordinator); Susan Cotter, OD, MS (Vice Chair); Richard Hertle, MD (Vice Chair); Michael Rouse, OD, MS (Consultant)
CITT Data Coordinating Center
Gladys Lynn Mitchell, MAS, (PI); Tracy Kitts, (Project Coordinator); Melanie Bacher (Programmer); Linda Barrett (Data Entry); Loraine Sinnott, PhD (Biostatistician); Kelly Watson (student worker); Pam Wessel (Office Associate)
National Eye Institute, Bethesda, MD
Maryann Redford, DDS, MPH
CITT Executive Committee
Mitchell Scheiman, OD; G. Lynn Mitchell, MAS; Susan Cotter, OD, MS; Richard Hertle, MD; Marjean Taylor Kulp, OD, MS; Maryann Redford, DDS., MPH; Michael Rouse, OD, MSEd
Data and Safety Monitoring Committee
Marie Diener-West, PhD, Chair; Rev. Andrew Costello, CSsR; William V. Good, MD; Ron D. Hays, PhD; Argye Hillis, PhD; (through March 2006); Ruth Manny, OD, PhD
Pennsylvania College of Optometry at Salus University
1200 West Godfrey Avenue
Philadelphia, Pennsylvania 19141
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Keywords:© 2011 American Academy of Optometry
accommodative dysfunction; accommodative amplitude; accommodative facility; accommodative insufficiency; convergence insufficiency; vision therapy; orthoptics; vergence/accommodative therapy; HTS