Characteristics of the Vergence Responses of Binocularly Normal Subjects After a Vision Therapy Protocol

A vision therapy protocol for vergence ability is mentioned. The purpose of this study is to evaluate objectively the change in the vergence responses of binocular and accommodative normal subjects after performing a classic vision therapy protocol. This study is an interventional, cross-over, and randomized study.

After the first evaluation, subjects will be classified in the Experimental Group (EG) or Control Group (CG) randomly. There will be 18 subjects in each group. A classic vision therapy protocol for fusional vergence will be performed in the EG and the CG will be doing a placebo therapy, based on studies done before.

The EG will do weekly office-based therapy of 45 minutes during 12 weeks and the CG will do weekly office-based placebo therapy of 15 minutes during 12 weeks. This placebo therapy will consist of smooth-pursuit and discrimination exercises that do not influence vergence response. The office-based done by the EG consists of a vergence therapy and its protocol will follow Scheiman's indications protocol. This vision therapy will train both positive and negative fusional vergence amplitudes in the same proportion.

A pre-evaluation, a during evaluation, and a post-evaluation will be done at weeks 1, 6, and 12 respectively to all subjects. After the post-evaluation week, the CG will do 12 weeks more of office-based therapy but, this group will do the same conventional vergence protocol as EG. The CG will be evaluated at week 18, and finally, at week 24.

During the evaluations, the vergence eye movements will be measured during the positive and negative fusional vergence tests. The break and the recovery points will be evaluated to all the subjects with three different methods performed in a randomized order: (1) objective computer-based test in the haploscopic system, (2) prism bar, and (3) phoropter rotary prisms. All these tests will be performed at 40 cm with a classic central visual target.

This study aims to evaluate objectively the change in the vergence responses of binocular and accommodative normal subjects after performing a classic vision therapy protocol.

Eligibility Criteria:
Normal binocular and accommodative subjects will participate in the study. All subjects have to fulfill the inclusion criteria. All evaluations will consist of the following objective and subjective optometric tests, which will be executed for all participants.

1. Monocular and binocular VA at near and distance with their habitual correction
2. Refractive error measured with the Grand Seiko WAM-5500 Autorefractor
3. Cover Test at near (40 cm)
4. Near Point of Accommodation
5. Near Point of Convergence
6. Vergence Facility Test at near (40 cm)
7. Monocular and binocular Accommodation Facility Test at near (40 cm)
8. Negative and Positive Relative Accommodation Test (ARN and ARP)
9. Random Dot 2 Stereo acuity Test
10. CISS questionnaire
11. Fusional Vergence Amplitude using both subjective and objective methods

Exclusion Criteria:

* having eye surgery
* having an eye pathology
* having a binocular or an accommodative disorder
* using orto-K lenses