Have Chronic Neck Pain? How is your near point convergence and why you should measure it.

Chronic Neck Pain has a direct relationship with oculomotor function.

(measuring near point convergence (NPC) distance)

A recent study by Esteves et al. (2025) investigated how those with chronic neck pain also have a variety of dysfunctions with the ocular (eye) muscles and delayed eye reaction times. What still remain unclear is where the dysfunction of afferent (sensory information) from the cervical spine to the central nervous system (CNS) is a cause or an effect of dysfunctional ocular muscle control. Specifically, we are talking about convergence insufficiency (CI) as being a clinical sign of ocular muscle motor control dysfunction. When one has CI, it means that near point convergence (NPC) ability is reduced. It is also common that those who have visual disturbances (dizziness, blurred vision, eye strain/ fatigue, light sensitivity) to have impaired oculomotor control and chronic neck pain and/or stiffness.

For the body to be in a relaxed, homeostatic condition, it requires accurate proprioceptive sensory input from three major sources:

1)     Cervical mechanoreceptors located in the:

a.      Facet joints

b.     Intervertebral discs

c.      Muscle spindles

2)     Vestibular Organs

a.      Semicircular canals (cranial nerve VIII)

3)     Visual Pathway

a.      Field of vision (cranial nerve II) and integration with the occipital lobes and brainstem

With chronic neck pain, we often have a reduction in range of motion and poor quality joint motion which takes out accurate sensory input for the CNS to process and thus requires more input from vestibular and visual pathways. However, if the visual pathway inputs are also compromised, the CNS is really limited for accurate proprioception. The default “safe mode” for the body is maintaining a more rigid, hyperactivation of the intrinsic core stabilizers of the spine. Then we can further reduce the ROM in the neck, begin or exacerbate the formation of trigger points, leading to further deterioration of the input from cervical mechanoreceptors. It becomes a terrible vicious cycle of:

1)     Decreased afferent input into the CNS

2)     Reflexive CNS response to increase muscle tone of the intrinsic neck and spinal musculature (like the suboccipital muscle groups) to try to elicit further sensory input

3)     Tonic musculature resulting in ischemic local focal regions

4)     Leads to pain and trigger point formation

5)     Results in further decrease in ranges of motions.

6)     Cycle continues...

Thus, the main reason of this article is to give hope that if CI is present and you have chronic neck pain, a means of breaking the cycle can be to train and restore ocular motor control, increasing accurate proprioception, requiring less input from the cervical spine which can ease tension and pain in that region.

Lastly, a few quick definitions before we proceed:

1)     CI can be determined both subjectively and objectively

a.      Objectively:

                                                    i.     Exam findings of exophoria. This means that when you focus on a distant object, then cover one eye. Then uncover that eye and watch for the immediate movement afterwards. If as soon as the eye is uncovered, it move back towards the nose (i.e. move medially) then a form of exophoria is present. This means that the default “neutral” of that eye wants to cause the eye to wander outwards, laterally, which impacts the ability to converge the eye.

                                                  ii.     Measuring near point convergence (NPC)

1.     Definition: the distance from your face whereby you can focus without having double vision. You can use special devices, or a pen tip or finger.

2.     Normative values vary by age and device used. Generally speaking, 5-10cm for adults and 6-7cm for children

b.     Subjectively

                                                    i.     Blurred vision

                                                  ii.     Diplopia

                                                iii.     Eye fatique

                                                iv.     Headache

                                                  v.     Difficulty reading

                                                vi.     Difficulty concentrating

According to Esteves et al. (2025), we can begin to establish some normative values for NPC as this is part of what their team sought to determine. The study had two groups, one with chronic neck pain (i.e. neck pain >10 days a month for 3+ months) and one group without neck pain (control group). Mean age was roughly 30 years old. Each group had 12 members (8 female & 4 males). Pertinent results as follows:

	Neck Pain Group	Control Group
Mean NPC distance	12.25cm	4.5cm

So, what do these results mean? It means that those with chronic neck pain have a significantly reduced ability in NPC. And good news if your NPC sucks and when you train it you can dramatically reduce your pain and improve your function (Abdel-Aal et al., 2024).  Thus, if you suffer from neck pain, eye fatigue, dizziness, light sensitivity, headache, diplopia and you test close to 12cm NPC compared to 4.5, then training ocular muscle-motor control might be a great intervention to restoring neck function and reducing (and hopefully eliminating) all of these symptoms.

References:

Abdel-Aal, Nabil & ElKeblawy, Maher & Amine, Randa. (2024). Effectiveness of eye-cervical re-education versus motor imagery therapy on chronic neck pain: A randomized controlled trial. SPORT TK-Revista EuroAmericana de Ciencias del Deporte. 6. 10.6018/sportk.605711.

Esteves, M. M., MacNeil, B., Tailor, G., Glazebrook, C. M., Johnson, M. G., & Passmore, S. R. (2025). Chronic Neck Pain Influence on Oculomotor Performance During Near Point Convergence and Fitts's Tasks: a cross-sectional study. Journal of manipulative and physiological therapeutics, 48(1-5), 119–128. https://doi.org/10.1016/j.jmpt.2025.08.005