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Table 1 Signs characterising normal binocular vision (NBV), convergence insufficiency (CI) and accommodative insufficiency (AI). (NFV-negative fusional vergence; PFV-positive fusional vergence; NPC-near point of convergence; RE-right eye)

From: Convergence insufficiency and accommodative insufficiency in children

Condition Signs
NBV 1. Distance phoria: between 3∆ exo and 2∆ eso
2. Near phoria: between 6∆ exo and 2∆ eso
3. Near NFV ≥ x/7/3 (∆)
4. Near PFV ≥ x/15/10 (∆)
5. NPC break ≤6 cm
6. Amplitude of Accommodation (RE): AA > (15–0,25*Age)-2 (Hofstetter’s minimum age formula)
7. Monocular Accommodative Facility (RE): MAF ≥ 6 cpm
CI 8. Near exophoria 4∆ greater than distance phoria
9. PFV break < 15∆ or failing Sheard’s criterion
10. NPC break > 6 cm
AI 11. Monocular AA 2D ≤ Hofstetter’s minimum age formula: 15–0,25*Age
12. MAF < 6 cpm (difficulty clearing − 2,00D)
OBD OBD’s include children with tests outside normal limits not included in previously categories.