The shooter, referred to as Guardsman 1 in a report from the Defence Safety Authority, only met the military's minimum entry standards when he was wearing his lenses.
A soldier who was fatally injured during a training exercise was probably mistaken for a firing target by a short-sighted colleague who was not wearing his lenses, a report has found.
Sergeant Gavin Hillier, 35, of the 1st Battalion Welsh Guards, died at the Castlemartin range in Pembrokeshire on 4 March last year. The shooter, referred to as Guardsman 1 in a report from the Defence Safety Authority, only met the military's minimum entry standards when he was wearing his lenses.
On the day that Sergeant Hilier was hit, it is likely that Guardsman 1 "mistook Sgt Hillier for the SFT (switch fire target)" the report found. Not wearing his lenses was something that "significantly impacted" his "ability to identify, acquire and subsequently engage the correct target".
In order for Guardsman 1 to see the same amount of detail as a normally sighted person, he would need to be "three times closer if using both eyes (binocular vision), or six times closer using just their right eye", the report added.
On the night of the incident, the shooter was approximately 290 metres from the target he should have been aiming at. With uncorrected vision, he would have seen the target "in the same detail as someone with normal vision would have seen it at 1,740 metres", the report said.
The shooter, who had been in the Army for 18 months at the time of the incident, had previously been refused entry because of a "visual acuity".
A number of recommendations have made to avoid something similar happening in future. They include ensuring soldiers who need lenses realise they have a responsibility to wear them "for all safety-critical duties". There is also a call for an "assurance mechanism" to ensure they are wearing them "prior to live firing".
Sgt Hillier had a "distinguished career", the Ministry of Defence has said previously, and was deployed on operations in Kosovo, Iraq and Afghanistan. His wife said: "We are absolutely heartbroken and can't express how proud we are of you. "Our boys will continue to make you proud and you will forever live on through them."
An inquest into Sgt Hilier's death was opened at Pembrokeshire and Carmarthenshire Coroner's Court last year.
A spokeswoman for the Army said: "Our thoughts and sympathies remain with the family and friends of Sergeant Gaven Hillier at this sad time. "We are supporting the ongoing investigation into the incident which is being led by Dyfed-Powys Police so it would be inappropriate to comment further."