Primary Outcome Measure: Convergence Insufficiency Symptom Score
The CI Symptom Survey score showed a significant reduction in symptoms for patients in each of the three treatment groups (p < 0.001 for each group). Patients in the vision therapy/orthoptics group showed a reduction in symptoms from 36.5 + 8.7 to 20.7 + 12.2 (Table 5). Patients in the placebo vision therapy/orthoptics and pencil pushups groups also showed a decrease in mean symptom score (placebo from 37.5 + 11.4 to 25.2 + 10.3, pencil pushups 37.6 + 7.7 to 26.5 + 7.3), although this change was not as large as that observed in the vision therapy/orthoptic group. There were no statistical differences in the CI Symptom Survey score among the three treatment groups at eligibility (p = 0.86) or at the completion of treatment (p = 0.15).
Figure 3 shows the mean CI Symptom Survey score at eligibility and after 4, 8, and 12 weeks of treatment for patients in each treatment arm. After 12 weeks of treatment, the mean CI Symptom Survey score for patients assigned to vision therapy/orthoptics decreased to a level that would be considered nonsymptomatic (i.e., a CISS-V15 score of <21). Neither the mean score for the pencil pushups group nor placebo vision therapy/orthoptics group ever fell below this level.
Secondary Outcome Measures
Figure 4 shows the mean near point of convergence at eligibility and after 4, 8, and 12 weeks of treatment for patients in each treatment arm. There were statistically significant changes in the near point of convergence in all groups. However, only the vision therapy/orthoptics group showed a clinically significant improvement (6 cm or less). The near point of convergence break improved in the vision therapy/orthoptics group decreasing from 12.8 cm + 7.7 to 5.3 cm + 1.7 (p = 0.002). There was a statistically significant improvement in the mean near point of convergence break measurement in the pencil pushups group (12.5 cm + 6.6 to 7.8 cm + 4.1, p = 0.001) and the placebo vision therapy/orthoptics group (14.5 cm + 7.8 to 9.6 cm + 4.0, p = 0.04), although the changes are not considered clinically significant. Sixty-seven percent (eight of 12) of the patients in the vision therapy/orthoptics group achieved a normal near point of convergence break measurement of <6 cm at the end of treatment, whereas 23.1% (3 of 13) of the placebo vision therapy/orthoptics group and 46.7% (7 of 15) of the pencil pushups group achieved this result.
A comparison of the mean values at the end of treatment demonstrated a significant difference in the near point of convergence break values between the three treatment groups (p = 0.02). Post hoc testing revealed that the mean near point of convergence break for the vision therapy/orthoptics group was significantly different from the mean of the placebo vision therapy/orthoptics group (p = 0.02). There was no significant difference when comparing the pencil pushups group with the vision therapy/orthoptics group (p = 0.18) nor to the placebo vision therapy/orthoptics group (p = 0.43). If we compare the near point of convergence break between groups after imputing values for the six patients who did not complete the entire 12 weeks of treatment, the difference between groups becomes nonsignificant (p = 0.27). The mean for patients in the vision therapy/orthoptics group increased to 7.1 + 4.3 cm, which is no longer significantly different from the mean value for patients in the placebo vision therapy/orthoptics group (mean = 9.5 + 3.9 cm, p = 0.25).
Figure 5 shows the mean positive fusional vergence at near at eligibility and after 4, 8, and 12 weeks of treatment for patients in each treatment arm. The positive fusional vergence break at near increased significantly in the vision therapy/orthoptics group from 11.3Δ + 4.3 to 29.7Δ + 10.8 (p = 0.001). Patients in the placebo vision therapy/orthoptics group experienced a statistically significant improvement from 11.5Δ + 4.4 to 17.5Δ + 5.7 (p = 0.003) and those in the pencil pushups group improvement significantly from 13.6Δ + 7.1 to 24.2Δ + 12.5 (p < 0.001). The mean positive fusional vergence break values at the outcome visit differed significantly between the three groups (p = 0.002). The mean for patients in the vision therapy/orthoptics group was significantly different (improved) compared with the mean for patients in the pencil pushups group (p = 0.04) and those in the placebo vision therapy/orthoptics group (p = 0.002). No difference was observed between the pencil pushups and placebo vision therapy/orthoptics groups (p = 0.36).
Adherence to Treatment
To assess adherence, the therapist asked the patient questions about the home-based treatment and then answered the following question on the CITT follow-up form: “What percent of the time do you feel the patient adhered to the treatment protocol?” The choices were: 0%, 1–24%, 25–49%, 50–74%, 75–99%, or 100%.
There were no differences in the therapist’s assessment of patient adherence between the three treatment groups at any visit. After 4 weeks of treatment, the therapists estimated that 61.5% of patients in the vision therapy/orthoptics group, 91.7% of patients in the placebo vision therapy/orthoptics group, and 61.5% of those in the pencil pushups group were performing their home therapy at least 75% of the time (Kruskal-Wallis p = 0.12). At 8 weeks, the therapists’ estimates were 69.2% for the vision therapy/orthoptics group, 91.7% for the placebo vision therapy/orthoptics group, and 61.5% for the pencil pushups group (Kruskal-Wallis p = 0.07). The percentage of patients estimated to adhere to home therapy at least 75% of the time decreased for all three treatment groups at the 12-week visit, but the estimates were still not significantly different from each other. In the vision therapy/orthoptics group, therapists estimated that 50.0% of the patients performed their home therapy at least 75% of the time. This compares with the 69.2% estimated for patients in the placebo vision therapy/orthoptics group and 86.7% estimated for patients in the pencil pushups group (Kruskal-Wallis p = 0.08).
Placebo Treatment—Were Patients Masked?
To determine the effectiveness of masking the patients assigned to the two office-based treatments (i.e., vision therapy/orthoptics and placebo vision therapy/orthoptics), patients were asked at the 12-week examination if they thought they were randomized into the “true” or the “placebo” treatment. In addition, they were asked how sure they were about their answer. The results (Table 6) indicated that 75% of the patients assigned to placebo vision therapy/orthoptics believed they had been assigned to the real vision therapy/orthoptics group and 44% of these were very sure or pretty sure of their answer. Of the patients assigned to real vision therapy/orthoptics, 90% believed they had been assigned to real vision therapy/orthoptics group and all were very sure or pretty sure of their answer.
It could be argued that if a patient was successfully masked to treatment assignment, that the patient would be equally likely to choose “vision therapy” or “placebo” when asked about perceived group assignment. This would equate to a 50/50 split in the percentage responding “vision therapy” or “placebo.” For those patients assigned to vision therapy, significantly more chose “vision therapy” than would have been expected by chance (p = 0.011). However, among those patients assigned to placebo vision therapy, the percentage choosing “placebo” was not significantly different from 50% (p = 0.083). This lack of significance could certainly be attributed in part to the small sample size (n = 13). Although not significant, it is important to note that patients assigned to placebo were more likely to respond “vision therapy.” Thus, it would appear that successful masking of treatment assignment was achieved in the group assigned to placebo vision therapy.
“Cured” and “Improved” Criteria
Patients who achieved a score of <21 on the CISS-V15 and had both a normal near point of convergence and normal positive fusional vergence at near were considered “cured.” In the vision therapy/orthoptics group, three of 12 (25.0%) patients achieved these criteria, whereas no patients in the placebo vision therapy/orthoptics group or in pencil pushups did so. Patients who achieved a decrease in symptoms (<21 on the CI Symptom Survey–V15) and achieved normal values in either the near point of convergence or positive fusional vergence at near were considered “improved.” In the vision therapy/orthoptics group, three of 12 (25%) patients achieved this criteria, whereas two of 13 (15.4%) in the placebo vision therapy/orthoptics group and two of 15 (13.3%) in pencil pushups group did so.
In this first randomized, placebo-controlled, multicenter clinical trial studying the treatment of symptomatic CI in young adults, office-based vision therapy/orthoptics improved the signs associated with CI. Both the average near point of convergence and the average positive fusional vergence at near improved to roughly normal clinical values, although 58% of the patients in this group were still considered to be symptomatic after 12 weeks of treatment. There were statistically significant but not clinically relevant improvements in both the mean near point of convergence and the mean positive fusional vergence break at near in the pencil pushups and placebo office-based vision therapy/orthoptics groups. In addition, 80% of those in the pencil pushups treatment group and 69% of those in the placebo vision therapy/orthoptics group were still considered to be symptomatic after 12 weeks of treatment.
If we instead consider both symptom level and clinical findings to classify patients as “cured” or “improved,” patients receiving vision therapy/orthoptics again fared better than patients in either of the other two treatment groups. After 12 weeks of treatment, 50% of patients in the vision therapy/orthoptics group were either “cured” (three of 12 or 25%) or “improved” (three of 12 or 25%). In contrast, none of the patients assigned to pencil pushups and placebo vision therapy/orthoptics group were “cured,” and only two of 13 (15%) in the pencil pushups and two of 15 (13%) in the placebo vision therapy/orthoptics group were “improved.”
These findings are surprising in light of previous studies demonstrating a significant decrease in symptoms after orthoptic treatment for CI in adults. Both Cooper23 and Grisham,14 in reviewing the literature, reported that over 90% of patients with CI reported elimination of their symptoms. Most of the studies reviewed by these authors reported on adult patients with CI. However, these findings were based on papers that were retrospective, uncontrolled and did not use a valid instrument to assess symptoms before and after treatment. In these studies, patients simply reported their symptoms verbally to the doctor before and after treatment. This approach is prone to interpretation error and experimenter bias.
However, in one cohort of symptomatic patients with CI, Cooper15 used an automated computer program to present vergence stimuli in an A–B crossover design to systematically treat eight adult patients. Positive reinforcement, time of treatment, and therapy stimuli used were the same in the two groups except that half of the patients received vergence therapy, whereas the other half received placebo nonvergence therapy. After end-point criteria were achieved, the two treatment groups were reversed, i.e., those receiving vergence therapy received placebo and vice versa. Those patients receiving vergence therapy demonstrated a mean 18r increase in positive fusional vergence to a posttreatment mean of 30r BO and a change in symptom score from moderately uncomfortable to almost symptom-free. It is surprising that in our slightly larger cohort, we did not achieve a comparable decrease in asthenopia, especially in light of the fact that various accommodative and vergence treatment procedures were performed.
One could argue that a longer treatment period may have resulted in additional changes. After 12 weeks of treatment, the mean symptom score for the patients in the vision therapy/orthoptics group decreased below 21 (i.e., considered asymptomatic) for the first time and did not appear to have reached a plateau yet. Perhaps additional improvement would have occurred after more treatment visits. We struggled with determining the appropriate length of treatment time when we were planning this study. Although traditional in-office vision therapy/orthoptics for patients with CI may require anywhere from 12 to 24 office visits,8,9 we selected the minimum number of visits because we thought it would 1) be sufficient length of treatment time for adult patients with CI and 2) because we wanted to minimize the number of treatment sessions for those assigned to placebo treatment. We were also concerned that the longer the treatment program, the more the potential for retention problems with the placebo treatment group.
Another issue is what happens to symptoms, near point of convergence, and positive fusional vergence at near over time. The CITT study was not designed to look at long-term results. This question needs to be answered in a prospective, large-scale, randomized clinical trial.
The results from this study of young adults with symptomatic CI are also different from the results we reported for children with symptomatic CI.18 In the previous study of children with CI, we found a statistically significant improvement in both clinical signs and symptoms using the same 12-week vision therapy/orthoptics regimen. Pencil pushups treatment was not found to be effective in decreasing signs or symptoms in children with CI, and in fact, pencil pushups was no more effective than placebo vision therapy/orthoptics. One simple explanation for the treatment differences found between the children and adults in these two studies is that CI can be more effectively treated in children than adults. However, previous retrospective research described here suggests that this may not be true. Because clinical findings improved in the vision therapy/orthoptics group to approximately the same degree in both children and adults, the two groups may have responded differentially to the CI Symptom Survey. Perhaps young adults in college or in the work force spend more time reading or using computers or experience more nonvisually related symptoms that might mimic the visual symptoms tested on the CI Symptom Survey and thus remain symptomatic even after treatment. The higher mean scores for patients 19 to 30 years of age compared with those 9 to 18 years of age18 and the higher cut point for an asymptomatic score on the CISS V-1519 suggest that this may be true.
We attempted to control for the effect of the “therapist as a placebo”24 because it has been reported that the enthusiasm, caring, and compassion of a therapist may play a key role in treatment outcome.25 We did this by designing placebo therapy that simulated bona fide procedures, and training the therapists to behave identically for patients in both the vision therapy/orthoptics and placebo vision therapy/orthoptics groups. We believe that the data reported here confirms that we were successful in achieving this objective because 75% of the patients assigned to placebo vision therapy/orthoptics believed they had been assigned to the vision therapy/orthoptics group.
This study was designed as a pilot study to prepare the CITT Study Group for a large-scale randomized clinical trial. As such, there are a number of limitations that must be considered when interpreting the results of this study. First, the sample size of 46 patients was small, which affects the precision of our treatment effects. Second, although the retention rate for this study was acceptable and patient loss was not related to treatment assignment, six of 46 (13%) patients were dropped from the study or did not complete the 12 weeks of treatment within the window for the outcome visit. A third potential issue was the 12-week treatment period. Perhaps a longer treatment period may have resulted in additional changes in signs and symptoms. Finally, it will be critical in future studies to investigate the long-term outcome of any treatment for CI.
This first multicenter, randomized clinical trial of the treatment of symptomatic CI in young adults demonstrated that of the three treatment modalities, only vision therapy/orthoptics was effective in achieving normal clinical values for both the near point of convergence and positive fusional vergence. Patients in the pencil pushups group achieved normal values only for positive fusional vergence at near and patients in the placebo vision therapy/orthoptics group did not achieve normal findings for either the near point of convergence or positive fusional vergence at near. Therefore, the effectiveness of vision therapy/orthoptics in improving the near point of convergence and positive fusional convergence values at near in adults cannot be explained on the basis of a placebo effect. Based on the results of this preliminary study, it would appear that pencil pushups, the most popular treatment for CI, is not effective for achieving clinically significant improvements in symptoms or signs associated with CI in young adults.
THE CONVERGENCE INSUFFICIENCY TREATMENT TRIAL (CITT) STUDY GROUP CLINICAL SITES
Listed in order of number of patients enrolled into the study, with city, state, site name, and number of patients in parentheses. Personnel are listed as (PI) for principal investigator, (I) for investigator, (C) for coordinator, and (T) for therapist.
Columbus, OH—The Ohio State University College of Optometry (15)
Marjean Taylor Kulp (PI), Michael J. Earley (I), Andrew J. Toole (I), Heather R. Gebhart (T), Ann M. Hickson (T)
Fullerton, CA—Southern California College of Optometry (13)
Susan A. Cotter (PI), Michael W. Rouse (I), Eric Borsting (I), Susan M. Shin (I), Raymond H. Chu (I), Carmen N. Barnhardt (I), John H. Lee (I), Yvonne Flores (C)
New York, NY—State University of New York, College of Optometry (12)
Jeffrey Cooper (PI), Jerry Feldman (I), Audra Steiner (I), Rose Hughes (T), Jennifer Colavito (T), Esperaza Samonte (C)
Philadelphia, PA—Pennsylvania College of Optometry (3)
Mitchell Scheiman (PI) Michael Gallaway (I), Jo Ann Bailey (I), Karen Pollack (T)
University of Houston College of Optometry (2)
Janice Wensveen (PI)
Forest Grove, OR—Pacific University College of Optometry (1)
Richard London (PI), Jayne L. Silver (T)
Columbus, OH, The Ohio State University College of Optometry, Optometry Coordinating Center
G. Lynn Mitchell (PI), Linda Barrett (I)
Supported by the National Eye Institute of the National Institutes of Health, Department of Health and Human Services grant EY13164-01. The authors thank Karla Zadnik, OD, PhD, and Israel A. Goldberg, PhD, for their advice and help in the development of the research design for this study.
Pennsylvania College of Optometry
1200 West Godfrey Ave.
Philadelphia, PA 19141
1.Duke-Elder S, Wybar K Ocular motility and strabismus. In: Duke- Elder S, ed.System of Ophthalmology. St. Louis: Mosby; 1973:547-51.
2.von Noorden GK. Binocular Vision and Ocular Motility: Theory and Management of Strabismus, 5th ed. St. Louis: Mosby; 1996.
3.Abrams D. Duke-Elder’s Practice of Refraction, 10th ed. Edinburgh: Churchill-Livingstone; 1993.
4.Cibis G, Tongue A Evaluation of asthenopia in childhood. In: Cibis, G, Tongue A, Stass-Isern M, eds. Decision Making in Pediatric Ophthalmology. St. Louis: BC Decker; 1993:208-9.
5.Pratt-Johnson JA, Tillson G. Management of Strabismus and Amblyopia: A Practical Guide, 2nd
ed. New York: Thieme; 2001.
6.von Noorden GK, Helveston EM. Strabismus: A Decision Making Approach. St. Louis: Mosby; 1994.
7.Griffin JR, Grisham DJ. Binocular Anomalies: Diagnosis and Vision Therapy, 4th ed. Boston: Butterworth-Heinemann; 2002.
8.Press LJ. Applied Concepts in Vision Therapy. St. Louis: Mosby; 1997.
9.Scheiman M, Wick B. Clinical Management of Binocular Vision: Heterophoric, Accommodative and Eye Movement Disorders, 2nd
ed. Philadelphia: Lippincott Williams & Wilkins; 2002.
10.Hugonnier R, Clayette-Hugonnier C. Strabismus, Heterophoria and Ocular Motor Paralysis: Clinical Ocular Muscle Imbalance. St. Louis: Mosby; 1969.
11.Gallaway M, Scheiman M, Malhotra K. The effectiveness of pencil pushups treatment for convergence insufficiency: a pilot study. Optom Vis Sci 2002;79:265–7.
12.Chin B, Faibish B, Hisaka C, Thal L, Tsuda K. A survey of the treatment of convergence insufficiency by optometrists in the greater San Francisco Bay Area. J Beh Optom 1995;6:91–2, 109.
13.Scheiman M, Cooper J, Mitchell GL, de, LP, Cotter S, Borsting E, London R, Rouse M. A survey of treatment modalities for convergence insufficiency. Optom Vis Sci 2002;79:151–7.
14.Grisham JD. Visual therapy results for convergence insufficiency: a literature review. Am J Optom Physiol Opt 1988;65:448–54.
15.Cooper J, Selenow A, Ciuffreda KJ, Feldman J, Faverty J, Hokoda SC, Silver J. Reduction of asthenopia in patients with convergence insufficiency after fusional vergence training. Am J Optom Physiol Opt 1983;60:982–9.
16.Daum K. Double-blind placebo-controlled examination of timing effects in the training of positive vergences. Am J Optom Physiol Opt 1986;63:807–12.
17.Birnbaum MH, Soden R, Cohen AH. Efficacy of vision therapy for convergence insufficiency in an adult male population. J Am Optom Assoc 1999;70:225–32.
18.Scheiman M, Mitchell GL, Cotter S, Cooper J, Kulp M, Rouse M, Borsting E, London R, Wensveen J. A randomized clinical trial of treatments for convergence insufficiency in children. Arch Ophthalmol 2005;123:14–24.
19.Rouse MW, Borsting EJ, Mitchell GL, Scheiman M, Cotter SA, Cooper J, Kulp MT, London R, Wensveen J. Validity and reliability of the revised convergence insufficiency symptom survey in adults. Ophthal Physiol Opt 2004;24:384–90.
20.Hayes GJ, Cohen BE, Rouse MW, De Land PN. Normative values for the nearpoint of convergence of elementary schoolchildren. Optom Vis Sci 1998;75:506–12.
21.Sheard C. Zones of ocular comfort. Am J Optom 1930;7:9–25.
22.Borsting EJ, Rouse MW, Mitchell GL, Scheiman M, Cotter SA, Cooper J, Kulp MT, London R. Validity and reliability of the revised convergence insufficiency symptom survey in children aged 9 to 18 years. Optom Vis Sci 2003;80:832–8.
23.Cooper J, Duckman R. Convergence insufficiency: incidence, diagnosis, and treatment. J Am Optom Assoc 1978;49:673–80.
24.Margo CE. The placebo effect. Surv Ophthalmol 1999;44:31–44.
25.Brody H. The doctor as therapeutic agent: a placebo effect research agenda. In: Harrington A, ed. The Placebo Effect: An Interdisciplinary Exploration. Cambridge, MA: Harvard University Press; 1997: 77-92.
Keywords:© 2005 American Academy of Optometry
convergence; insufficiency; vision therapy; orthoptics; pencil push-ups; placebo; exophoria; eyestrain; symptoms