A visual impairment shall be determined through the manifestation of both of the following:
(a) A visual impairment which, even with correction, interferes with development or which adversely affects educational performance. Visual impairment includes both partial sight and blindness.
(b) One or more of the following:
(i) A central visual acuity for near or far point vision of 20/70 or less in the better eye after routine refractive correction.
(ii) A peripheral field of vision restricted to not more than 20 degrees.
(iii) A diagnosed progressively deteriorating eye condition.