Over the past 19 years we have received very positive feedback from colleagues and ­students about the first three editions of this book. They have remarked that this book is easy to read and understand, and that it provides valuable information about the diagnosis and treatment of binocular vision. We have also continued to receive excellent constructive criticism and suggestions and as in the past we have tried to respond to these suggestions in this new edition.

In both editions 2 and 3, it was necessary to add new chapters to respond to reader suggestions. For this edition, however, we have not added any new chapters. Rather, the main purpose of this new edition is to refresh the book with the latest research and evidence supporting the evaluation and treatment protocols suggested. Over the course of 5 years there have been new research ­studies and other new literature that are relevant to the topics covered in this text. We have carefully reviewed this new literature and have incorporated information from these studies when appropriate.

One of the other important changes has been the introduction of new technology and equipment for vision therapy. We have tried to include information about new vision therapy equipment in this new edition in Chapters 6–8. Finally, all of the illustrations in the book have been updated and a majority of the illustrations are now in color.

We hope that the updated material will make this fourth edition even more useful than the previous editions for faculty designing courses, students studying these topics for the first time, and established practitioners looking for a practical, easy-to-use reference on accommodative, ocular motility, and non-strabismic vision anomalies.

Mitchell Scheiman, O.D.

Bruce Wick, O.D., Ph.D.

One of the authors (M.S.) acknowledges individuals who have had a strong influence on his professional development and the field of binocular vision and vision therapy:

Dr. Jerome Rosner, who was so instrumental in teaching me how to teach in the very early stages of my career and giving me the push I needed to get involved in didactic teaching; Drs. Nathan Flax, Irwin Suchoff, Jack Richman, Martin Birnbaum, and Arnold Sherman, who inspired me to devote my professional career to the areas of vision therapy, pediatrics, and binocular vision; all the investigators of the Convergence Insufficiency Treatment Trial who have helped complete the first large-scale randomized clinical trial of vision therapy for the treatment of convergence insufficiency.

Dr. Michael Gallaway, for his personal and professional support over the last 30 years, Dr.  Barbara Steinman, for her outstanding work in designing the illustrations for the second, third, and fourth editions of this book; my family, for their support, and for showing so much patience with me during my many months of writing.

I (B.W.) wish to acknowledge my father, Dr. Ralph Wick, for his assistance and support throughout my career. In addition, thanks to Drs. Monroe Hirsch, Merideth Morgan, and Mert Flom, who all strongly influenced my development in the field of binocular vision and vision therapy. Above all, thanks to my wife Susan for everything.

After a thorough case history and determination of the refractive error, the first important step in the management of accommodative, ocular motor, and nonstrabismic binocular vision problems is the diagnostic testing routine. In this chapter we discuss testing procedures for assessing accommodation, binocular vision, and ocular motor skills. The emphasis is on presentation of important issues, considerations, and expected values for the various tests. The setup and administration of these tests is summarized in the Appendix to this chapter.

All measures of alignment and accommodation require an accurate full-plus refraction with a binocular balance. It is useful to perform a binocular refraction technique that yields a maximum plus refraction. Such an examination often requires an initial objective determination of the refractive error. This can be accomplished with static retinoscopy, autorefraction, or even starting with the patient’s previous refractive correction. To perform a modified binocular refraction, we recommend the following ­procedure:

1. Use a 20/30 line (or an acuity line two lines above threshold).

2. With the left eye occluded, add plus (0.25 diopter [D] at a time) to the objective findings until the right eye is barely able to read the 20/30 threshold line. If too much plus is used, the next step will be difficult, so you may want to back off slightly (add −0.25 D, at most).

3. Perform Jackson cross-cylinder (JCC) testing. Adding plus in the step above allows the patient to make more accurate JCC responses.

4. Repeat for left eye, with right occluded.

5. Add prism (3 Δ up before the right eye; 3 Δ down before the left) and +0.75 D to each eye.

6. Perform a dissociated balance by adding plus to the clearer target, until both are reported to be equally blurred.

7. Remove the dissociating prism and slowly add minus, until the patient can just read 20/20. Do not ­arbitrarily add some amount of minus!

8. Place the vectographic slide in the projector with analyzers in the phoropter. Place “I” target with letters on each side in the patient’s view and ask if both sides are equally clear. If not, add +0.25 D to the clearer side. This is a binocular balance, but not a true binocular refraction where the JCC would be performed under these conditions as well; it is generally not necessary to perform a JCC here unless the patient has a significant astigmatism (>1.00 DC) and a torsional phoria is suspected.

9. Perform associated phoria measures and stereopsis testing.

10. Return to the standard slide and check visual acuity. If the patient cannot see 20/15, check whether −0.25 more OU improves the acuity. It is virtually never necessary to add more than −0.50 OU total. Do not arbitrarily add some amount of minus!