In manga, a man's gaze is often firmer.
The eyebrow must be straighter, and its edge thinner.
The eye begins one third of the way along the eyebrow. The lines must be very straight.
The upper eyelid should almost be a straight line.
The eye shouldn't be too big, otherwise it will bring out the man's softer side.
The lower eyelid can end in a triangle to accentuate the effect of his gaze.
The internal structure of the eye doesn't change. The pupil remains the darkest part. The edge of the eye must be darker than the center.
Then you need to fill in the eyebrow. If it is darker than the pupil, it means you have to darken the pupil again since it must always be the darkest part of the eye.