From time to time a proposal surfaces in the ASTM F8.53 Subcommittee to add a new parameter to the standard for bicycle helmets to ensure an unobstructed field of vision. It is not something like impact protection or strap strength where the consumer must have lab test results. Riders can tell what they can see, and they know if the helmet is interfering. Helmet designers are well aware that riders need to see in front, and the adequate vision clearance in current helmets indicates that this requirement is being satisfied without ASTM testing for it.
Consumers can choose a helmet that meets their needs for forward vision.
The current ASTM standard is the most-used standard in the world. There are millions of ASTM-certified helmets in use every day without field of vision problems. That indicates that current helmets are performing well without field of vision requirements in our standard. As with any testing, adding field of vision requirements would force designers to allow extra room in front to make sure that they could pass the test in different labs using different test personnel. Foam thickness equates to more stopping distance, and assuming the foam in most helmets will be similar, cutting away front foam to increase clearance for vision beyond actual requirements will reduce the protection of the helmet in front, known to be a site of frequent impacts where maximum protection is important.