Neurophysiology of vision studies the physiological mechanisms that make visual perception possible. It evaluates the complex mechanisms that transform light stimuli into electric stimuli and their transmission from the retinal photoreceptors to the visual cortex.
Neuro-ophthalmology. The loss of visual function can be linked not only to eye diseases but also to pathologies that may involve those portions of the brain (optical nerve, optical chiasm, optical tract, lateral geniculate nucleus, optical radiation, occipital cerebral cortex) used for the transmission and decoding of visual information. In this context, the pathologies of the optical nerve play a key role, which may be due to diabetes, glaucoma, demyelinating pathologies (multiple sclerosis), ischaemic phenomena, toxic or iatrogenic processes, infectious processes, autoimmune diseases (SLE, rheumatoid arthritis), hypo-allergenic diseases, neurodegenerative diseases (degenerative ataxias, Alzheimer's disease, Parkinson's disease) neoplastic processes, trauma. In addition, many pathologies of the optic nerve are caused by genetic mutations such as Leber hereditary optic neuropathy or the dominant or recessive hereditary optical neuritis.
The pathologies of the optic nerve manifest themselves with a progressive or acute loss of visual acuity, with a deficit of the visual field, with changes in chromatic perception or contrasts.
Depending on the localization of the neuritic process, the pathologies of the optic nerve may be anterior (and in this case typical modifications of the head of the optic nerve or ophthalmoscopic visible optic papilla) or retrobulbary (non-negativity of the ophthalmoscopic examination are observed).
In order to provide a correct diagnostic framework, an accurate anamnestic connection, a visual acuity assessment even after cycloplegia, eye motility tests, perimeter or campimetric examinations, electrofunctional tests (ERG, PERG, F-ERG, mfERG, MfERG, PEV), morphological retinal and optic nerve evaluations by means of OCT examinations, a targeted neuroradiological diagnosis are essential. The therapy, which must be established as early as possible, is mainly based on cortisone or neuropathic drugs (e. g. cyticoline).
Other pathologies of the central nervous system such as migraine headaches (with or without visual aura), TIA., ictus, cerebral infarctions, neoplastic pathologies, head injuries, can induce visual perception deficits or specific losses of part of the visual field. In this case, the diagnostic framework is very similar to that of neuropathy, while as far as therapy is concerned, it is linked to the basic pathology.
In addition, various pathologies that recognize inflammatory, vascular, neoplastic or toxic, metabolic etiology may induce other unnecessary visual system dysfunctions associated with changes in visual perception such as diplopia (paralytic strabisms), adaptive deficits, ptosis or abnormalities of the pupil diameter. Also in this case the diagnostic framework is very similar to that of neuropathy and the therapy is related to the basic pathology..