Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 86. Blinding Laser Weapons
Section B. Laser systems incidentally causing blindness
The UK LOAC Manual (2004) states:
6.15. “It is prohibited to employ laser weapons specifically designed, as their sole combat function or as one of their combat functions, to cause permanent blindness to unenhanced vision”. These weapons must not be transferred to other states or non-State entities.
6.15.1. Other laser systems may be employed against military objectives, for example, against military optical equipment even though this may cause incidental effects, including blindness, to the users of that equipment.
6.15.2. “In the employment of laser systems, … all feasible precautions” must be taken “to avoid the incidence of permanent blindness to unenhanced vision.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 6.15–6.15.2.
In 1998, in a letter to the ICRC President, the UK Secretary of Defence stated: “The capabilities of weapons systems under development which employ lasers, and the concepts of operation for their use, are already consistent with the [1995 Protocol IV to the Convention on Certain Conventional Weapons].” 
United Kingdom, Letter from the Secretary of Defence to the ICRC President, 23 March 1998.