Table 1.

Diagnostic criteria used for NSBVA diagnosis.

1. Convergence insufficiency

1. Exophoria > 4 BI greater for near than distance

2. NPC > 6 cm break with accommodative target

3. PFV < 15 BO (break or blur value)

2. Divergence insufficiency

1. Esophoria > 2 BO for distance

2. NFV < 7 BI (break – step vergence for distance)

3. Convergence excess

1. Significant esophoria at near, >2 prisms

2. Reduced negative fusional vergence < 13/10 for break and recovery

3. High MEM, >+0.75 DS

4. Divergence excess

1. Intermittent to constant exodeviation for distance 5 PD greater than near

2. Low PFV break value of <11 BO for distance

5. Accommodative insufficiency

1. Reduced monocular amplitude of accommodation at least 2 D below Hofstetter's calculation for minimum amplitude: 15–0.25 (age)

2. Difficulty with monocular accommodative facility with −2.00 DS

3. High MEM finding, >+0.75 DS

6. Accommodative infacility

1. Difficulty with both plus and minus lenses in monocular accommodative facility testing with <7 cpm for 8–12 year old and <13 cpm for 13 years and above with ±2.00 DS

2. Difficulty with both plus and minus lenses in binocular accommodative facility testing with <5 cpm using ±2.00 DS

8. Fusional vergence dysfunction

1. Near NFV break <12 BI

2. Near PFV break <23 BO

3. Distance NFV break <7 BI

4. Distance PFV break <11 BO

For diagnosis: a minimum of 2 signs are mandatory

Adopted and modified from Scheiman and Wick (2014).¹⁶