A bead of sweat slipped down his forehead, along the crease between his brows and into his eye.
- I struggle with eyes, arms, hands, feet... I don't want to write 'into his left eye', as it seems odd to specify which eye. I don't want to write 'into an eye', which sounds as though there is a random eye lying around. But does 'into his eye' suggest that he only has one?