My heart hath turned round The verb which David here uses signifies to travel or wander hither and thither; but here it is taken for the agitation or disquietude which distress of heart engenders when we know not what to do. According as men are disquieted in mind, so do they turn themselves on all sides, and so their heart may be said to turn round, or to run to and fro. But since faith, when it has once brought us into obedience to God, holds our minds fixed on his word, it might here be asked by way of objection, How it is that the heart of David was so affected by disquietude and trouble? To this I answer, That although he continued to walk in the ways of God, while he was sustained by the promises of God, yet he was not altogether exempted from human infirmity. And, indeed, it will always happen, that as soon as we fall into some danger, our flesh will suggest to us various shifts and devices, and lead us into many errors in search of counsel; so that even the most confident would fail and go astray, unless he laid upon himself the same restraint by which David was preserved and kept in subjection, namely, by keeping all his thoughts shut up within the limits of God's word. Nay, even in the prayers which we offer up when our minds are at ease, we experience too well how easily our minds are carried away, and wander after vain and frivolous thoughts, and how difficult it is to keep them uninterruptedly attentive and fixed with the same degree of intensity upon the object of our desire. If this happen when we are not exercised by any severe trial, what will be the case when we are agitated by violent storms and tempests which threaten a thousand deaths, and when there is no way to escape them? It is, therefore, no great wonder if they carried away the heart of David, so that it was subject to various emotions amidst such tempestuous agitations. He adds, that his strength had failed him, as if he had compared himself to a dead man. What he adds concerning the light of his eyes some understand as if he had said, that he was so much oppressed with despair on all sides, that no counsel or foresight was left to him. The more simple meaning, however, is, that the light of life was taken away from him, because in it the energy of the soul principally shows itself.

My heart panteth - The word rendered "panteth," in its original form, means properly to go about; to travel around; and then, to travel around as a merchant or pedlar, or for purposes of traffic: Genesis 23:16; Genesis 37:28; Genesis 42:34. Applied to the heart, as it is here, it means to move about rapidly; to palpitate; to beat quick. It is an expression of pain and distress, indicated by a rapid beating of the heart.
My strength faileth me - It is rapidly failing. He regarded himself as rapidly approaching death.
As for the light of mine eyes - My vision; my sight.
It also is gone from me - Margin, as in Hebrew: "is not with me." This is usually an indication of approaching death; and it would seem from all these symptoms that he appeared to be drawing near to the end of life. Compare Psalm 13:3; Psalm 6:7; Psalm 31:9.

My heart panteth - סחרחר secharchar, flutters, palpitates, through fear and alarm.
My strength faileth - Not being able to take nourishment.
The light of mine eyes - is gone - I can scarcely discern any thing through the general decay of my health and vigor, particularly affecting my sight.

My heart panteth, my strength faileth me: as for the light of mine eyes, (h) it also is gone from me.
(h) My sight fails me for sorrow.

My heart panteth,.... Or "goes about" (m); runs here and there, and finds no rest; as Aben Ezra interprets the word from the Targum he cites; though the Targum we have renders it, "my heart shakes with fear", or dread, as persons in a fever. Jarchi interprets the word, surrounded with grief; it denotes the panting or palpitation of the heart, through sorrow and dread, and the failing of it, even as at death;
my strength faileth me, or "forsakes me" (n); bodily strength and spiritual strength; the strength of faith, hope, and confidence;
as for the light of mine eyes, it also is gone from me; which is often the case of persons under bodily disorders, their eyes grow dim, and sight fails them; and this might be true in a spiritual sense of the psalmist, who had lost sight of God as his covenant God; of his interest in his love, in the blessings of his grace, and in eternal salvation, and was walking in darkness, and saw no light.
(m) "circuivit", Pagninus, Montanus, Vatablus. (n) "dereliquit me", Pagninus, Montanus, Junius & Tremellius, Piscator; so Musculus, Cocceius.

My heart panteth--as if barely surviving.
light . . . from me--utter exhaustion (Psalm 6:7; Psalm 13:3).