Academic journal article Journal of Visual Impairment & Blindness

Restoration of Vision Following Long-Term Blindness: Considerations for Providing Rehabilitation

Academic journal article Journal of Visual Impairment & Blindness

Restoration of Vision Following Long-Term Blindness: Considerations for Providing Rehabilitation

Article excerpt

Restoration of vision has been a dream of science and part of human folklore and religion for centuries (Gregory & Wallace, 1963; Mark 8:22-26). Substantive scientific efforts have been ongoing since the 1960s (Brindley & Lewin, 1968). The disease that has attracted major efforts in this regard has been retinitis pigmentosa (Pagon, 1988), a secondary retinal degeneration process caused by any of a multitude of mutations in one of the many genes encoding proteins in the retinal photoreceptors and underlying pigment epithelium (Daiger, Sullivan, & Bowne, 2013). There has been encouraging progress in therapeutic interventions seeking to lessen vision loss or to slow down progression of the disease through dietary supplements (Berson et al., 2010) or to halt the degenerative process through replacement therapy of small genes using an adenoviral vector (Bennett et al., 2012). Even gene replacement may not halt the degeneration process, however (Cideciyan et al., 2013), and differentiation of stem cells into photoreceptors and successful integration, even into the retina, may be many years away (West et al., 2012). For the foreseeable future, therefore, the best hope for restoring vision may come from electrical stimulation of secondary retinal cells and transmission of the activity to the visual cortex, substituting electrical for physiological stimuli. A demonstration of the ability of a person who is blind from retinitis pigmentosa to perceive stimulation of the retina through a single electrode was reported in 1996 (Humayun et al., 1996), and just 20 years later there are two commercially available products that provide rudimentary eyesight to blind persons (Humayun et al., 2009; Stingl et al., 2013). In the Argus II Retinal Prosthesis System, a 6 x 10 electrode grid covering a 12[degrees] x 20[degrees] area of the central retina conveys a crude image, extracted from a head-mounted video camera by a belt-pack processor and transmitted wirelessly to an electronics capsule on the outside of the eye (Humayun et al., 2012). In the Alpha IMS, a 10[degrees] x 10[degrees] grid of 38 x 40 units, each containing a photocell, amplifier, and electrode, is placed under the retina, with external power provided wirelessly through the scalp (Gekeler et al., 2006). Both systems are capable of providing the implantee with shadowy gray-scale images of the outside world. Clinical trials have shown that patients receiving these implants can learn to detect and follow markings on a floor (Humayun et al., 2012); locate (Ahuja et al., 2011); and identify (Dorn et al., 2012) objects and track movement (Stingl et al., 2013) on a screen; recognize letters (da Cruz et al., 2013; Zrenner et al., 2011); and perform simple hand-eye coordination tasks (Barry & Dagnelie, 2012).

The authors have experience with the Argus II Retinal Prosthesis System by Second Sight Medical Products (Sylmar, California). The Argus II is the first vision restoration device with market approval in the European Economic Area and the United States for patients blinded by retinitis pigmentosa. This system was designed to create visual percepts by electrically stimulating the remaining retinal cells, following loss of sight due to the degeneration of the rod and cone photoreceptors. The authors also have decades of experience with native low vision and blindness due to age-related macular degeneration, diabetes, glaucoma, and retinitis pigmentosa, to name only the most common causes of low vision in developed countries.

Drawing on our background of working with the rehabilitation of native low vision and now of restored vision, we will compare and contrast traditional rehabilitation for low vision with this new challenge: rehabilitation of restored low vision following decades of blindness. The life experience of a patient with restored vision following years of blindness offers unique opportunities and challenges for both the patient and the provider of rehabilitation. …

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