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)

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.