Low Vision and Aniridia
Low Vision and Aniridia
Aniridia affects many visual aspects of one’s life. This chapter will highlight many of these effects. Functional changes that occur due to aniridia will be discussed. Once the patient’s vision is assessed and goals are established with a thorough eye examination, numerous avenues can be taken to ensure the support of all the patient’s health care providers. Referrals can be made to appropriate professionals to ensure full understanding and management of the ocular condition. Visual acuity is the measurement used to determine vision levels. Normal vision is 20/20, which means that what a normal person sees at 20 feet, the patient sees at 20 feet. If their vision is 20/40, they would need to be at a distance of 20 feet to see what someone with normal vision can see at 40 feet. The decrease in visual acuity in those with aniridia usually ranges from under 20/60 to as low as approximately 20/400. This is due to the lack of development of the macular area, or fovea. The fovea is responsible for our clearest, most precise vision. Those with visual acuity of 20/200 or worse that is best corrected while wearing spectacles or contact lenses in the better-seeing eye are considered legally blind. While most people who suffer from aniridia are not legally blind, they are visual impaired. Visual impairment is defined as visual acuity of 20/70 in the better-seeing eye when optimally corrected with glasses or contact lenses. The designation of “visual impairment” also has a functionality factor. If a person has a reduction in the ability of the eye or the visual system to perform to a normal ability, he/she is considered visually impaired. Visual field is the measurement of peripheral vision. Those with aniridia may have decreased peripheral vision. This is not directly due to aniridia, but rather to glaucoma, which may develop due to structural changes in the eye. Glaucoma is explained in detail in the glaucoma chapter of this book.
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