***DISCLAIMER***The following is far from an exhaustive answer to the question. It is simply an answer nonetheless.
Recently, someone asked me if his sin was the cause of his losing his eyesight. What follows is his question followed by my response to it.
Hi. I am a Christian. I am losing my eyesight now. Is this because of my sin? I am totally hurt.
First, my sincerest condolences to you and your eye-sight. I cannot imagine what that is like.
As for the reason why you are losing your eye-sight, it is not because of some personal sin in your life. Unfortunately, this world is broken because of the sin of Adam, as Romans 5:12-21 states:
Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned— 13 for until the Law sin was in the world, but sin is not imputed when there is no law.14 Nevertheless death reigned from Adam until Moses, even over those who had not sinned in the likeness of the offense of Adam, who is a type of Him who was to come.
15 But the free gift is not like the transgression. For if by the transgression of the one the many died, much more did the grace of God and the gift by the grace of the one Man, Jesus Christ, abound to the many. 16 The gift is not like that which came through the one who sinned; for on the one hand the judgment arose from one transgression resulting in condemnation, but on the other hand the free gift arose from many transgressions resulting in justification. 17 For if by the transgression of the one, death reigned through the one, much more those who receive the abundance of grace and of the gift of righteousness will reign in life through the One, Jesus Christ.
18 So then as through one transgression there resulted condemnation to all men, even so through one act of righteousness there resulted justification of life to all men. 19 For as through the one man’s disobedience the many were made sinners, even so through the obedience of the One the many will be made righteous.20 The Law came in so that the transgression would increase; but where sin increased, grace abounded all the more, 21 so that, as sin reigned in death, even so grace would reign through righteousness to eternal life through Jesus Christ our Lord.
Adam’s sin brought death and condemnation to all men. This means Adam’s sin brought condemnation to you and me (in addition to the entire human race). As a result, we live in a broken, fallen, sinful world. The reason people have cerebral palsy (such as Word-Faith apologist Justin Peters), bad hearing and/or (in your case) bad eyesight (among other deformities and the like) is because of this fallen, sin-filled world we inhabit.
This may lead to the question of whether or not it is always God’s will for one to be healed. Those with deformities may pray desperately for healing. However, while God can still do physical, miraculous healings, it is not always God’s will for one to be healed. 2 Corinthians 12:7-10 explains a bit more on this (NASB):
Because of the surpassing greatness of the revelations, for this reason, to keep me from exalting myself, there was given me a thorn in the flesh, a messenger of Satan to torment me—to keep me from exalting myself! 8 Concerning this I implored the Lord three times that it might leave me. 9 And He has said to me, “My grace is sufficient for you, for power is perfected in weakness.” Most gladly, therefore, I will rather boast about my weaknesses, so that the power of Christ may dwell in me. 10 Therefore I am well content with weaknesses, with insults, with distresses, with persecutions, with difficulties, for Christ’s sake; for when I am weak, then I am strong.
Here, the apostle Paul clearly discusses a messenger of Satan that was given to him to torment him (verse 7). Paul pleaded three times for this to be removed (verse 8). God stated that His grace was sufficient for Paul (verse 9). Paul then goes on to list the various things he is content with for Christ’s sake (verse 10). This man, Paul, wrote roughly half the New Testament. Certainly he would have qualified as one who could have been healed. However, it was not God’s will for him to be healed.
In summary, people have defects, bad eyesight and other things because of this sinful, fallen world we inhabit. While it is not always God’s will for man to be healed, the Christian can take heart that this physical body, broken and imperfect as it is, will not be the same body here and in eternity. There will come a time that will feature no more tears, death, mourning, crying or pain (Revelation 21:1-9). I will pray that God may heal your eyesight. However, take courage, believer, that if you are not healed now, you will be in eternity.
Blessings. Hope you found this helpful.