Peripheral neuropathic pain is often described as "burning", "tingling", "electrical", "stabbing", or "pins and needles". Causes
Pathophysiology
Under persistent activation, the transmission of pain signals to the dorsal horn may produce a pain wind-up phenomenon. This triggers changes that lower the threshold for pain signals to be transmitted. In addition, it may cause nonnociceptive nerve fibers to respond to, generate, and transmit pain signals. The type of nerve fibers that are believed to generate the pain signals are the C-fibers, since they have a slow conductivity and give rise to a painful sensation that persists over a long time. In chronic pain, this process is difficult to reverse or stop once established. In some cases, chronic pain can be caused by genetic factors which interfere with neuronal differentiation, leading to a permanently lowered threshold for pain.Chronic pain of different causes has been characterized as a disease that affects brain structure and function. MRI studies have shown abnormal anatomical and functional connectivity, even during rest involving areas related to the processing of pain. Also, persistent pain has been shown to cause grey matter loss, which is reversible once the pain has resolved.These structural changes can be explained by neuroplasticity. In the case of chronic pain, the somatotopic representation of the body is inappropriately reorganized following peripheral and central sensitization. This can cause allodynia or hyperalgesia. In individuals with chronic pain, EEGs showed altered brain activity, suggesting pain-induced neuroplastic changes.
Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause
Causes include:

Refractive errors
Divergence insufficiency
Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.Unlike esotropia, fusion is possible and therefore diplopia is uncommon. References


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