Commentary of Charles Spurgeon, Adam Clarke & Matthew Henry
While the sun, or the light, or the moon, or the stars, 
be not darkened, nor the clouds return after the rain:
Vs.2
Then the sun
and the light of it, the moon and the stars, and the light
which they borrow from it, will be darkened.
They look dim to old people,
in consequence of the decay of their sight;
their countenance is clouded, and
the beauty and luster of it are eclipsed; their intellectual powers and
faculties, which are as lights in the soul, are weakened; their understanding
and memory fail them, and their apprehension is not so quick nor their fancy so
lively as it has been; the days of their mirth are over (light is often put for
joy and prosperity).
Then the clouds return after the rain;
as, when the weather is disposed to wet, no sooner has one cloud blown over than
another succeeds it, so it is with old people, when they have got free from one
pain or ailment, they are seized with another, ....but the beginning of another, and deep calls unto deep. 
While the sun, or the light, or the moon, or the stars, be not darkened - i.e., in the Spring, prime, and prosperity of life.
Nor the clouds return - The infirmities of old age of which Winter is a proper emblem, as spring is of youth, in the former clause of this verse.
The decays and infirmities of old age are here elegantly
described in figurative expressions, —to show how
uncomfortable, generally, the days of old age are.
