Visually Impaired Persons: Assess and Assist

Опубликовано 17 мая 2019, 18:48

Visually Impaired Persons: What must be Understood to Assess and Assist.

Until approximately 10 years ago abnormalities of focus were the primary cause of vision loss and the focus of ophthalmic and optometric clinicians worldwide. However with the improvement in the methods to measure and repair the ocular optics (spectacles, contact lenses, corneal and cataract surgery), the major cause of mild, moderate, and severe vision loss throughout the world has now become macular disease caused by the severe rapid expansion of diabetes as well as the aging population, The difficulties in managing retinal disease are caused by three significant problems: 1)The failure of patients to seek attention of an ophthalmic provider until vision abnormalities interfere sufficiently with daily visual function, most often defined by when the second eye becomes involved because the brain in daily function merges the images of the two eyes to one composite with varying dominance. 2) The physician fails to understand the vision deficit because of the reliance on chart acuity, which fails to measure functional vision. 3)The physician relies upon retinal examination to define the onset of disease. Although current laser coherence tomography imaging can define the structural abnormalities with considerable improvement, the images are typically interpreted with failure to attach digital quantification of the abnormalities, or currently with the use of engineering-derived digital measurements that are poorly associated with defining the function of the retina under conditions of varying luminance and color-contrasts.

This discussion will present a vision of what must be done in order to detect, understand, and predict the course of macular disease in the individual patient so that treatment can be instigated sufficiently early to prevent functional loss.

First the diabetic at first diagnosis and those persons genetically at risk of developing macular degeneration must undergo multi-wavelength, coherence, tomography imaging at regular intervals with the images registered and presented in overlay so that dynamic changes over time can be understood and quantitated.

Second, the monocular and binocular vision of an individual must be measured in the central visual field in a dynamic situation that mimics real-world luminance and contrasts of typical photopic or mesopic tasks. The results then must be overlaid upon the retinal structural changes in order to understand the relationships of alterations in photoreceptor, middle nuclear layer, or ganglion cell nuclear pathologies with the vision changes. Once this is done, then we can understand the interactive central field of vision and how it is altered under varying luminance conditions of tasks the person is trying to perform and can understand the effects of the pathology and how to prevent, not reverse this process.

Finally then, this will improve our understanding of how to assist those vision tasks the individual wishes to perform. We must switch from focusing on lenticular magnification to understanding the importance of off-axis illumination and reduction in glare with enhancement of edge contrast perception together with shadows that will improve motion parallax detection and depth perception, whether for the individual sitting and trying to crochet, the surgeon performing endoscopic surgery, or the athlete playing on the field. We must understand the problems the central visual field Swiss cheese produces on reading and change the dynamics of the interaction.

So many of these tasks can be certainly be accomplished better with electronics than optics.

See more at microsoft.com/en-us/research/v...