Sailors who meet the universal criteria for legal blindness are eligible to compete in BSI regattas.  Since legal blindness does not mean total blindness, it is necessary to establish an equitable method of grouping sailors for fair competition.  BSI has traditionally adopted the International Blind Sports Association (IBSA) classification of vision, widely used for other international and world class competitive events.

IBSA Classification of Vision
B1   Total Absence of perception of light in both eyes, or some perception of the light but with the inability to recognize the form of a hand at any distance and in any direction.
B2 From the ability to recognize the form of a hand to a visual acuity of 2/60 and/or visual field of less than 5 degrees.
B3 From a visual acuity of above 2/60 to a visual acuity of 6/60 and/or a visual field of more than 5 degrees and less than 20 degrees.
Under this system the B1, B2 and B3 sailors currently race in three separate divisions, according to the vision classification of the helmsman.

It is important to recognise that this classification is extremely important as the athlete’s classification is subject to verification by an IBSA certified doctor.
Classification forms are required to be submitted with entry by all regatta entrants completed by a registered Ophthalmologist.

A Simple Explanation copied from British Blind Sport Website
Ophthalmologists decide if you can be registered as blind if you can only read the top letter of the eye chart from three metres or less. You can be registered as partially sighted if you can only read the top letter of the eye chart from six metres or less.“

So, if blindness has varying degrees, how do VIs playing sport compete fairly?

This is resolved by a Sight Classification system, introduced by IBSA (International Blind Sports Federation), and used by BBS throughout the UK. Much like the ‘handicap’ system in golf, or even the weighting of horses in races, it allows for fairness when playing and competing and is defined by IBSA as follows:
“The classes were defined primarily by acuity and secondarily by field and the definitions are as follows:-

B1 ‘No light perception in either eye up to light perception but inability to recognise the shape of a hand at any distance or in any direction.’

B2 ‘From the ability to recognise the shape of a hand up to visual acuity of 2/60 and/or visual field of less than 5 degrees.’

B3 ‘From visual acuity above 2/60 up to visual acuity of 6/60 and/or a visual field of more than 5 degrees and less than 20 degrees.’”

Within the UK it has been decided by some sports that for social and historical reasons, a fourth class of B4 should be established and be determined purely by acuity. This class ranges from the top of ‘B3’ to an acuity of 6/24 Snellen. An individual with an acuity of 6/24 would be able to read the three top lines on a Snellen chart at six metres.”
To help you get to grips with these classes, here is some further explanation:

B1is quite straight forward – applicable if at best you can’t do better than distinguish between light and dark.

B2 and B3 are more of a problem for fully sighted people to understand. Most people
have had their sight tested at one time or another. Imagine looking at an optician’s chart. This has letters displayed in lines. The top line has one letter, the second line two, the third line three and so on. If you can only read the top letter at two metres distance, then you have an acuity of 2/60. If you can read at it six metres then you have an acuity of 6/60.
Next, imagine you are standing in the middle of a clock face and looking towards 12 o’clock. If you can only see what exists between half a minute to 12 and half a minute past 12 then you have a visual field of six degrees. If you can see one and a half minutes to twelve and one and a half minutes past 12 then you have visual field of 20 degrees.
Inevitably there is a problem for those who are on the borderline of the categories and even more so for those above the international B3 standard. The general view of BBS is that wherever possible the blind should integrate into mainstream competition.

A B4 classification is accepted in some Junior IBSA competitions and in many domestic competitions.

To obtain a formal sight classification you need to take the sight classification form, available from Head Office, to an optician, ophthalmologist or consultant and once completed return it to the office where it will then go to a sight classifier who allocates the appropriate classification. A sight classification card is then despatched and is accepted throughout disability sport. When attending international competition, particularly for the first time, further classification tests will be required and changes can be made.

Download Sight Classification Form