![]() The pupil describes the aperture defined by the iris, which regulates the amount of light entering the posterior chamber of the eye and therefore influences the image at the retina. ![]() This case illustrates why an assessment of the pupils is an essential part of every routine eye examination. In this case the pupils are diagnostic, objective and confirm other findings that are reliant upon the patient’s subjective input. ![]() So how to find if the left optic nerve is not working as well as the right? Check pupils.Ĭonfirmation of a left relative afferent pupil defect (see later) would confirm an issue with the optic nerve and the onset (age, hours onset, trigger by a hot bath – possible Uhthoff’s phenomenon) would lead to the reasonable conclusion of a retrobulbar neuritis. Likewise, unilteral vision loss would suggest a problem either in the left eye (ruled out by examination) or the left optic nerve. The progressive onset and her young age suggests a vascular problem is unlikely. So, at the risk of flippancy, was this actually an eye problem? Slit-lamp and fundoscopy showed no anomalies, binocular assessment likewise, and there was no other symptoms reported, other than the drop in acuity. The acuity in the affected eye had fallen to 6/36, and she reported the vision as ‘like looking through a fog.’ Colours seemed washed out, though colour vision testing and visual fields proved unreliable, if not impossible. By lunchtime, the vision had become cloudy enough for her to be concerned and to seek the opinion of a local optometrist. To complement our regular CPD features focusing on the latest advanced techniques in optometry, Optician will be publishing a regular series of primers covering the key techniques which are integral to the eye examination.Ī 23-year-old previously healthy female first noticed something wrong with her vision in the left eye when having a hot bath before going to work. So, consider the example in the next column. Visual acuity is, likewise, subjective by its very nature. Visual fields is heavily dependent upon patient response, which, as we all know only too well, can be variable to say the least. Until there is more widespread access to practice-friendly electrophysiological testing, assessing the way a pupil responds to light is the best way practitioners have of objectively assessing the functioning of the visual pathway. Pupil assessment is an objective test of neurological function.As such, clinical assessment of the pupil response to light elicits important information about the health of all these structures. The response of the iris to light levels and with accommodation is a result of a neural reflex pathway that involves the iris, retina, visual pathway, midbrain, and parasympathetic and sympathetic innervation of the eye.
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