Until recently, patients with progressive diseases that eventually lead to blindness have had little in the way of treatment, let alone a cure. Conditions such as retinitis pigmentosa and macular degeneration still stump doctors, and even the latest treatments, such as prescribing massive doses of vitamin
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A, only temporarily slow the progress of the disease in some patients. Currently, there is no failsafe way to reverse or even stop the progress of these diseases. Mechanical devices such as retinal implants seem to work with only a limited number of patientsreally, only those whose vision loss is caused by a retinal disorder. However, one new treatment is showing some promise, although it hasn't been thoroughly tested yet. Instead of focusing on dietary solutions, some doctors are attempting to develop an electronic one: a bionic eye that enables the user's brain to translate light impulses and create a virtual black-and-white "picture" of his or her surroundings. The picture, although accurate, only reflects a very limited field of vision, as if the patient had blinders on. Also, the picture moves fairly slowly, as if the patient were watching a film in very slow motion. But, being able to locate and identify objects is a definite first step in achieving everyday functional mobility for the visually impaired. Rather than the glass eye one might imagine, this artificial vision system consists of an elaborate apparatus that looks like a pair of binoculars, as well as a series of wires that are implanted directly into the patient's brain. The wires electrically stimulate the visual cortex, producing phosphenes, which blind people perceive as small points of light. The device then maps these phosphenes, gradually training the patient's brain to "see." One major advantage of the system, as opposed to other proposed treatments such as retinal implants, is that it is not condition specific: Patients can use it regardless of the cause of vision loss. For example, patients with genetic conditions such as retinitis pigmentosa, as well as patients with vision loss resulting from illness or accident, can use the device, since it directly stimulates the brain's vision center. In addition, its construction is fairly flexible and portable (the wires, in fact, are said to be hardly noticeable), and its utilities are far-reaching: One could envision a number of useful additional features, including zoom and night vision functions. In paragraph 2, why does the author use the phrase definite first step to describe the bionic eye? (A) It hasn't been thoroughly tested yet, and should not be viewed as a "cure" for blindness. (B) The device provides only limited vision, but it could be enough to improve mobility for users. (C) Advances in the bionic eye might lead to the development of more effective retinal implants. (D) It provides a viable alternative to dietary treatments.