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When we fixate on the optotypes we are able, under normal circumstances, not only to identify them but also to have a sense of all the surrounding space, without having to move our head or eyes.
The notion of this perception is called Visual Field, and its study is called Perimetry. In the Instituto de Microcirurgia Ocular, the study of the Visual Field is carried out in a computerized way through a device called Computerized Perimeter.
It is basically a dome that intends to reproduce our visual field, and where luminous stimuli are projected in various locations and of different sizes and intensities. The fact that this is a computerized analysis has the great advantage of eliminating factors of error arising from the subjectivity of the exam itself, not only from the examiner but also the patient, which makes it possible to have a fairly accurate idea of the reliability of the examination.
On the other hand, the evaluation programs are designed to compare the result of the exam with what is considered normal for the age and sex of the patient – which allows us to know the normality, or not, of the result with a high degree of probability – and allows us to compare tests carried out at different times, quantifying the changes, giving us a picture of the evolutionary character of the disease over time, which in some situations is of major importance in the therapeutic elaboration and orientation.
The study of the Visual Fields is performed essentially to characterize the diseases of the Retina, the Optic Nerve and the Optic Path – that is, of the whole nerve path that leads the visual information of the Eye to the Occipital Cortex, the part of the brain responsible for the vision.
In diseases of the optic nerve, we highlight glaucoma, where the perturbation of the Visual Field is often its first manifestation- that is, it is possible, in extreme cases, to have a visual acuity almost or equal to 100%, in reading or identifying the smallest letters or figures, and have a serious disturbance of the Visual Field.
Since the loss of the Visual Field, or of the sensitivity portion sensitivity of it, leads to a damage of the nerve fibers that is often irreversible, the assessment of the Visual Fields through the Computerized Perimetry is of major importance in ophthalmological evaluation.
With our equipment, it is possible to carry out Static Computing Perimetry as well as Computerized Kinetic Perimetry (equivalent to C.V. Goldmann).
