The changes were imposed by IPC and IBSA since the beginning of 2011.  It should be noted that for all sports, vision impaired athletes classified at the recent Paralympic games were done so using new methodology (tumbling Es) and the new definitions of the three IBSA classes. IFDS has notified BSI of changes to the Blind Sport Grading system.

The following link: IBSA-Sports Classification provides a detailed description of the developments.

Attached is a summary taken from the site.  And below is the new classification which uses a vision measurement system called Logmar instead of the original Snellen for sight measurement.  Also included is a conversion from Logmar to Snellen and it seems to only be more precise in measuring acuity.

The new system does not significantly modify the limits of visual field, as these were previously expressed in radius (eg. 5° or 20°) and are now expressed in diameter (eg. 10° and 40°) which is the same.

This should therefore have little or no impact on Classifications for future sailing events.

Definition of Visual Classes
The determination of visual class will be based upon the eye with better visual acuity, whilst wearing best optical correction using spectacles or contact lenses, and/or Visual Fields which include central and peripheral zones.

B1:
Visual acuity poorer than LogMAR 2.60.
2.6 logMAR converted to Snellen acuity is: 20/7962.14341107

B2:
Visual acuity ranging from LogMAR 1.50 to 2.60 (inclusive)
and/or Visual field constricted to a diameter of less than 10 degrees.
1.5 logMAR converted to Snellen acuity is: 20/632.455532034

B3:
Visual acuity ranging from LogMAR 1.40 to 1 (inclusive) and/or Visual field constricted to a diameter of less than 40 degrees.
1 logMAR converted to Snellen acuity is: 20/200
1.4 logMAR converted to Snellen acuity is: 20/502.377286302

A sight grading certificate can be downloaded from the following link
Sight Grading Form

The Sight Grading Form will be part of the Upcoming regatta documentation and can be obtained from the Organisers JBSA

A BSI Form will be available soon