Clinical test responses to different orthoptic exercise regimes in typical young adults

Abstract

Purpose: The relative efficiency of different eye exercise regimes is unclear, and in particular the influences of practice, placebo and the amount of effort required are rarely considered. This study measured conventional clinical measures following different regimes in typical young adults.

Methods: A total of 156 asymptomatic young adults were directed to carry out eye exercises three times daily for 2 weeks. Exercises were directed at improving blur responses (accommodation), disparity responses (convergence), both in a naturalistic relationship, convergence in excess of accommodation, accommodation in excess of convergence, and a placebo regime. They were compared to two control groups, neither of which were given exercises, but the second of which were asked to make maximum effort during the second testing.

Results: Instruction set and participant effort were more effective than many exercises. Convergence exercises independent of accommodation were the most effective treatment, followed by accommodation exercises, and both regimes resulted in changes in both vergence and accommodation test responses. Exercises targeting convergence and accommodation working together were less effective than those where they were separated. Accommodation measures were prone to large instruction/effort effects and monocular accommodation facility was subject to large practice effects.

Conclusions: Separating convergence and accommodation exercises seemed more effective than exercising both systems concurrently and suggests that stimulation of accommodation and convergence may act in an additive fashion to aid responses. Instruction/effort effects are large and should be carefully controlled if claims for the efficacy of any exercise regime are to be made.

Keywords: accommodation; convergence; fusion; orthoptic exercises; vision therapy.

Figure 1

Convergence measures. Pre- and post-treatment convergence measures for each treatment group. Abbreviations: NPC, Near point of convergence (in cm.)(NB Median and inter-quartile range error bars for this measure as not-normally distributed) VF, near vergence facility using 12ΔBO/3ΔBI flipper prisms. Group abbreviations; bl, blur/accommodation treatment; bo, both (simultaneous convergence and accommodation treatment); di, disparity (convergence treatment); con+, convergence in excess of accommodation treatment; acc+, accommodation in excess of convergence treatment; mo, motion (placebo treatment); ni, nil (no treatment controls); ef, effort, no treatment. *p < 0.01; **p < 0.001.

Figure 2

Accommodation measures. Pre- and post-treatment accommodation measures for each treatment group (Error bars: Standard error. BNPA, binocular near point of accommodation; MNPA, monocular near point of accommodation; BAF, near binocular accommodation facility; MAF, near monocular accommodation facility. Group abbreviations; bl, blur/accommodation treatment; bo, both (simultaneous convergence and accommodation treatment); di, disparity (convergence treatment); con+, convergence in excess of accommodation treatment; acc+, accommodation in excess of convergence treatment; mo, motion (placebo treatment); ni, nil (no treatment controls); ef, effort, no treatment. *p < 0.01; **p < 0.001.

Figure 3

Base out fusion ranges. Pre- and post-treatment BO PFR measures for each treatment group. NBOD, near BO fusion range to diplopia; NBOR, near BO fusion recovery; DBOD, distance BO fusion range to diplopia; DBOR, distance base out fusion recovery. Group abbreviations; bl, Blur/accommodation treatment; bo, both (simultaneous convergence and accommodation treatment); di, disparity(convergence treatment); con+, convergence in excess of accommodation treatment; acc+, accommodation in excess of convergence treatment; mo, motion (placebo treatment); ni, nil (no treatment controls); ef, effort, no treatment. *p < 0.01.

Figure 4

Base in fusion ranges. Pre- and post-treatment BI PFR measures for each treatment group. Nr BIFR Dip, near BI fusion range to diplopia; Nr BIFR Rec, near BI fusion recovery; Dist BIFR Dip, distance BI fusion range to diplopia; Dist BIFR Rec, distance BI fusion recovery. Group abbreviations; bl, blur/accommodation treatment; bo, both (simultaneous convergence and accommodation treatment); di, disparity (convergence treatment); con+, convergence in excess of accommodation treatment; acc+, accommodation in excess of convergence treatment; mo, motion (placebo treatment); ni, nil (no treatment controls); ef, effort, no treatment. (*),p < 0.05; *p < 0.01.