Appellants' only contention is that the board's decision to the effect that claimant's refusal to submit to a surgical operation designed to relieve his disability is not unreasonable, is erroneous as a matter of law. The question involved is essentially one of fact. The medical proofs that claimant's refusal to submit to the operation is unreasonable is opinion evidence. However, the nature of claimant's affliction, its history and the kind and character of the requested operation is such that we may not say the board's decision is without evidence to sustain it. Decisions and awards unanimously affirmed, with costs to the Workmen's Compensation Board.