Mine eye is consumed - The word here rendered "consumed" - עשׁשׁ ‛âshêsh - means properly to fall in, to fall away, and is applied here to the "eye" as pining or wasting away from care, anxiety, and sorrow. Tears were poured forth from the eye, and it seemed to be exhausting itself in this manner. The meaning is, that it had grown "dim," or that its sight began to fail, like that of an old man, on account of his troubles. Many have understood the word here rendered "eye" as referring to the "countenance;" but it is doubtful whether the word ever has this signification; and at any rate the common signification, referring it to the "eye," best suits this connection.
It waxeth old - It seems to grow old; it experiences the effects commonly produced by age in blunting the power of vision. This is not an uncommon effect of grief and sadness. Even while I am writing this I am called in my pastoral visitations to attend on a young lady lying on a bed of languishing, and probably of death, one of whose symptoms is a quite diminished, and indeed almost total loss of vision, as the effect of trouble and disease.
Because of all mine enemies - From the trouble which they have brought upon me. The reference here, according to the interpretation proposed of the psalm, is to Absalom and those who were associated with him. Their conduct had been such as to bring upon David this overwhelming tide of sorrows.

Mine eye is consumed - עששה asheshah, is blasted, withered, sunk in my head.

Mine eye is consumed because of grief,.... Either by reason of the affliction he laboured under, which could not he joyous, but grievous; or because, of the sin that was in him, and those that he had committed, which were grieving to him; or through the sins of other professors of religion, or profane sinners, whom he beheld with grief of heart and weeping eyes: the word (f) used signifies anger and indignation, and sorrow arising from thence, and may denote either indignation in himself at his enemies, who were rejoicing at his calamities; or the sense he had of the anger of God, and his hot displeasure, which he feared he was rebuking and chastening him with; and now his heart being filled with grief on one or other of these accounts, or all of them, vented itself in floods of tears, which hurt the visive faculty; for through much weeping the eye is weakened and becomes dim; and through a multitude of tears, and a long continuance of them, it fails; see Job 17:7;
it waxeth old because of all mine enemies; saints have many enemies, sin, Satan, and the world; and these are very oppressive ones, as the word (g) here signifies; such as beset them about, straiten them on all hands, and press them sore; and they must be pressed down by them, were it not that he that is in them is greater than he that is in the world; and David's enemies gave him so much trouble, and caused him to shed such plenty of tears, that his eye waxed old, was shrunk up, and beset with wrinkles, the signs of old age; or it was removed out of its place, as the word is rendered in Job 18:4; or the sight was removed from that, it was gone from him, Psalm 38:10.
(f) "prae ira", Pagninus; "prae indignatione", Montanus, Musculus; "ex indignatione", Piscator. (g) "angustiatores", Montanus; "angustiis afficientes me", Vatablus; "oppressores meos", Junius & Tremellius, Gejerus.

consumed--or, "has failed," denoting general debility (Psalm 13:3; Psalm 38:10).
waxeth old--or, "dim."
grief--mingled with indignation.