New approach to Visual Rehabilitation, “virtual reality” system P.G. Limoli
Introduction Impaired vision is a condition whereby a patient, affected by not reversible neurophthalmic pathology, is subject to a reduction of the visual function that cannot be corrected with standard lenses and results in visual disability in respect of the necessary visual needs (1, 2, 3, 4). In recent years the definition “low-vision” has certainly become more familiar in ophthalmology as this condition has become more frequent for two reasons: the senile population has increased steadily and as consequence the degenerative pathologies, which mainly affect the aged, are increasing; on the other side, the level of ophthalmic therapy and prevention has increased dramatically, especially after the 1970’s, this has reduced the number of patients whose illness resulted in blindness, and conversely increased the cases where therapy allows to maintain residual vision which if not useful in itself may at least be utilized (4). Patients may be defined low-vision for a variety of reasons. Some have impaired vision because of a central scotoma in their field of vision, others suffer of a general retinic sensitivity reduction, others are subject to tubular contraction, or various amputation of their visual field (3, 4). The common experience of those who examine these patients is that it is difficult to find two exactly similar low-vision patients. It is highly improbable that two patients have similar characteristics with regard to the type of pathology and its evolutionary trend, visual acuity (far and near), specific needs, clinical condition in both eyes, necessary magnification, preferred system reading speed, age, socio-cultural condition, etc. Variations observed in treating low-vision patients make statistical evaluations
unreliable and the application of a rational unified protocol is difficult. Testing various magnifying systems to ascertain which is the best one is a lengthy process. These lengthy tests reduce the patient's attention, quality of performance, precision of the choice, and finally increase the frustration of the patient. Our goal is to find a method to make the visual rehabilitation more simple, quick and precise. As a consequence, we suggest that the simulation of the condition of impaired vision may be useful in research on low vision. The basis of simulation as a research method is in fact the artificial reproduction of the phenomenon under examination, this phenomenon can be reproduced with the help of mathematical models, through its virtual rapresentations with a personal computer (5, 6, 7, 8, 9, 10). The following reasons suggest to replace the real object with a virtual one: first of all, the possibility to give an example and visualize schematically the concept of low vision, which is often not well defined; secondly, the opportunity to study a virtual model representing the patient without his necessarily being present, in other words the theoretical representation of a real case. The virtual model leads to other benefits motivations lead to other advantages: quickness and ease of use, the examination can be reproduced where and when desired, specially presents an accurate predictive different hypothetical solution to be applied after appropriate evaluation to the low vision patient while becoming a valuable education tool (11, 12, 13, 14, 15, 16, 17). We conducted a selection of the schematics aspects to represent vision in low vision patients.