Table 1.
Rate of convergence insufficiency (“common” (2 clinical signs) or “classic”/clinical (3 clinical signs)) and accommodative insufficiency (AI) in school-based study samples.
| Study | Age in years: range Mean (SD) |
N | CI∗ | CI∗ only, no AI† |
AI† | AI† only, no CI∗ |
CI∗ and AI† | |
|---|---|---|---|---|---|---|---|---|
| Letourneau and Ducic [6] | 6 to 13 — |
1954 | 2.3% | — | — | — | — | |
|
| ||||||||
| Rouse et al. [7] | 9 to 13 11.3 (0.6) |
453 | 13.0% | 4.9% | — | — | — | |
|
| ||||||||
| Borsting et al. [8] | 8 to 15 10.46 (1.41) |
392 | 17.3% | 10.5% | 17.3% | 10.5% | 6.9% | |
|
| ||||||||
| Marran et al. [1] | — 11.5 (0.63) |
299 | 18.1% | 14.7% | 8.0% | 4.7% | 3.3% | |
|
| ||||||||
| Wajuihian and Hansraj [9] | 13 to 19 16.27 (1.79) |
1201 | 12.2% | 10.3% | 4.5% | 2.6% | 1.9% | |
|
| ||||||||
| Present study | 8 to 15 11.67 (1.81) |
All students | 484 | 31.4% | 16.7% | 32.4% | 17.8% | 14.7% |
| No/low astigmatism | 212 | 26.9% | 11.8% | 33.0% | 17.9% | 15.1% | ||
| Moderate astigmatism | 126 | 34.1% | 22.2% | 31.0% | 19.0% | 11.9% | ||
| High astigmatism | 146 | 35.6% | 19.2% | 32.9% | 16.4% | 16.4% | ||
∗Convergence insufficiency (CI): presence of 2 or 3 clinical signs (exophoria at near greater than at far in addition to insufficient PFV and/or receded NPC) for all studies except Letourneau and Ducic [6] (defined only by near point of convergence >10 cm and exophoria greater at near than at distance).
†Accommodative insufficiency (AI): accommodative amplitude (AA) 2D from Hofstetter's minimum age expected AA, except for Wajuihian and Hansraj who defined AI by reduced accommodative amplitude combined with high values on monocular estimation retinoscopy and/or poor accommodative facility.