When diagnosing binocular conditions, it is a good idea to test the binocular system as a whole to understand how the eyes are working together and determine the underlying cause. Your basic binocular work-up should include:

• Assessment of extraocular muscles 

• Distance and near cover test

• Near point convergence (NPC)

• Saccades/pursuits

• Manifest refraction

• NRA/PRA

• Distance and near subjective phoria testing 

• Distance and near horizontal and vertical ranges

• Accommodative amplitudes 

You can consider additional tests such as:

• Monocular estimated method (MEM) retinoscopy to assess lead/lag of accommodation

• 9 positions of gaze

• NPC with a red lens

• AC/A ratio 

• Accommodative facilities 

• Vergence facilities 

• Cycloplegic refraction

• Description: A condition where the eyes struggle to converge for near tasks, resulting in symptoms like double vision, eyestrain, and reading difficulties.

• Treatment: Vision therapy, prism glasses, accommodative exercises.

• Emergency?: No, but it can be very debilitating.

• Helpful Testing: Expect to see a reduced NPC, reduced NRA, reduced convergence ranges, possible exophoria. 

• Differential Diagnoses: Accommodative insufficiency, binocular vision disorders, asthenopia.

• Description: Excessive contraction of the ciliary muscle leads to near vision blur and headaches, often triggered by prolonged near work.

• Treatment: Cycloplegic drops (e.g., atropine), rest, and managing visual demands.

• Emergency?: No, but discomfort can be significant.

• Helpful Testing: Expect to see a lead of accommodation, reduced divergence ranges, reduced NRA, difficulty clearing plus, less minus on cycloplegic refraction. 

• Differential Diagnoses: Accommodative insufficiency, refractive error, convergence excess.