Dr Dougal Watson told Coroner Brigitte Windley during the second day of an inquest into the death of William Bruce Andrews, had CAA been aware of issues Mr Andrews was experiencing, he would have been required to undergo a thorough assessment by an eye specialist.
''Depending on the outcome, he may or may not have been issued a medical certificate.''
Had he been, it would ''almost certainly'' have required ongoing checks.
Mr Andrews (49) died when the Hughes 500 he was piloting crashed in the Glade Valley on December 15, 2013.
Dr David Baldwin, of the Bulls Flying Doctor Service, told Ms Windley yesterday he examined Mr Andrews on November 2, 2013 and reissued his aero-medical certificate two days later, with a condition to have ''half glasses'' to assist with reading.
He was not aware Mr Andrews had been referred by his doctor to optometrist Daryl Parkes in December 2012, nor of Mr Parkes' findings, which included a large right posterior vitreous detachment.
That, he said ''could be'' of significance.
''In a pilot, I would want to know about that ... it should be reported to the Aero-Medical Examiner.
''I would seek that information, talk to the optometrist and depending [on the result of that] discuss with the CAA medical unit.''
Dr Baldwin said Mr Andrews was a ''highly professional pilot'', well-regarded by his peers in New Zealand and overseas and, in his experience, he was ''not someone that would conceal relevant health information that may have affected his ability to obtain a medical certificate''.
Mr Parkes believed his 2012 diagnosis would not have caused any sudden change in vision mid-flight. Issues Mr Andrews had been having with his sight in the days before the fatal crash may have been amaurosis fugax, in which vision is disrupted for up to a minute due to a temporary blockage of blood supply to the eye.
Someone with those symptoms ''really needs to see their medical practitioner to have a full blood work up because they are at risk of a stroke''.
''The risk there is something else going on is high.
''Flying-wise, I would not think that was prudent.''
Dr Baldwin disagreed.
''I couldn't imagine Bruce flying with that. Or anyone. They'd be on the phone [to a doctor] straight away.''
Meanwhile, consultant physician and professor of medicine Charles Beasley said there was a 0.5% chance Mr Andrews had deep vein thrombosis (DVT) leading to a pulmonary embolism.
Pathologist Roland Lass examined Mr Andrews on December 16, 2013 and determined the cause of death was ''massive, traumatic injuries''.
Mr Andrews' body was badly damaged and it was virtually impossible to confirm any medical cause. He believed if Mr Andrews had suffered a pulmonary embolism he would have been able to see that and ''there was none''.
The inquest continues.
