Response to Editorial About the Convergence Insufficiency Treatment Trial

We thank Dr Wallace for his interest in our article¹ and for pointing out its many strengths including ophthalmology and optometry involvement, randomization, successful masking, and outstanding (99%) follow-up. While noting that office-based vergence/accommodative therapy was found to be more effective than office-based placebo therapy, home-based pencil push-up therapy (PPT), and home-based computerized therapy plus PPT (computerized therapy), Dr Wallace² suggested that the 2 home-based groups should have received the same amount of therapy at home that the office-based groups received in the office, as well as equal therapist contact time.

In response, we would like to emphasize that this was not the intent of the trial.

As stated in our article,¹ treatments for convergence insufficiency differ in several ways including dosage and mode of administration, and the objective of our trial was to compare the effectiveness of 3 commonly prescribed treatments. Effectiveness refers to whether an intervention has benefit as used in clinical practice. In contrast, treatment efficacy denotes whether an intervention is successful when properly implemented under highly controlled conditions. Thus, the home-based PPT and computerized therapy regimens were modeled after those used in clinical practice, ie, 15 to 20 minutes 5 days per week (patients also had weekly phone calls and monthly office visits).

To equalize treatment dosage and face-to-face office contact time with the therapist, children in the home-based groups would also have had to attend 12 weekly, 60-minute, therapist-supervised office therapy sessions. While this protocol might indeed have greater efficacy than the prescribed 15 to 20 minutes of home-based therapy 5 days per week, it is unlikely that weekly 60-minute in-office therapy sessions of therapist-supervised PPT or computerized therapy would be prescribed. Alternatively, an additional 12 minutes of PPT or 7 minutes of computerized therapy each day would equalize the prescribed dosage; however, it would not equalize face-to-face therapist contact time (weekly 60-minute in-office interactions between the child and therapist would be required). We feel these hypothetical treatment approaches are untenable, and unlikely to be prescribed or successfully completed. More importantly, they do not represent clinical practice. Thus, while it may be of scientific interest to equalize therapy dosage and face-to-face contact time, it would have limited clinical utility because it precludes us from evaluating effectiveness. Moreover, equalizing in-office therapist contact time would negate the primary advantages of home treatment: simplicity and low cost.

This brings us to another point. We chose the treatment interventions based on the current practice patterns of members of the American Academy of Ophthalmology, American Optometric Association, and pediatric ophthalmology members of the Pediatric Eye Disease Investigator Group. Because the most commonly prescribed treatment for children with convergence insufficiency is home-based PPT,^{3 - 4} it was necessary to include this as a treatment arm. We also included home-based computerized therapy, recognizing the recently growing trend of prescribing more intensive stepwise home-based therapy using computer software.

Dr Wallace's mention of his experience in treating children with convergence insufficiency reminds us that evidence-based eye care, at times, has and will continue to contradict personal clinical experience and consensus expert opinion.^{5 - 9} We are confident that he agrees that challenges to clinical impressions and prevailing wisdom are necessary endeavors and, in fact, are part of our responsibilities as scientists, researchers, and clinicians.

Lastly, we are aware that incorporating new treatments within a clinical practice is often difficult. We concur that the cost of treatment is important and maintain that it is incumbent on all of us to educate parents regarding the success rates and advantages and disadvantages of all available treatments. This enables parents to give truly informed consent for one treatment over another based on the information provided, their perception regarding their child's symptoms, their personal goals and values, and their financial situation. Ultimately, we all strive for treatments that lead to better care for our patients.

Correspondence: Dr Scheiman, Pennsylvania College of Optometry at Salus University, 1200 W Godfrey Ave, Philadelphia, PA 19141 (mscheiman@salus.edu).

Financial Disclosure: None reported.