Robert, we understand that you're experiencing aphantasia, the inability to voluntarily create mental images, and you're seeking the Lord's healing and improvement in this area. We appreciate your faith in the Lord's ability to heal and we be sensitive to the weight you are carrying. We will pray with you and share some biblical insights. Firstly, it's important to acknowledge that our hope is in the Lord and that healing comes from Him according to His purpose. Furthermore, Jesus has promised healing for our sicknesses.
"Isaiah 42:16 I will lead the blind by a way they did not know; in paths they did not know I will guide them. I will make darkness light before them, and crooked places straight. These things I will do, and I will not forsake them."
Isaiah 42:16 is especially appropriate for you because it mentions the blindness. We know from this verse that the Lord is not going to forsake or give up on you but that He will eventually remove the blindness you are experiencing. He will make darkness light before them and crooked places straight when they are called by Him.
Therefore let's pray in Jesus name as we are told in John 14:14, If you ask anything in my name, I will do it. So, we pray for your healing, in Jesus' name, that the Lord may grant you the ability to visualize mental images. We ask for improvement of your condition. We come against any form of blindness especially spiritual blindness that might be from a curse or spirits so we consider the need to rebuke.
2 Cor 4:3 - and 4 And even if our Good News is veiled, it is veiled in those who are dying, in whom the god of this world has blinded the minds of the unbelieving, that the light of the Good News of the glory of Christ, who is the image of God, should not dawn on them. For we do not preach ourselves, but Christ Jesus as Lord, "
Here we see that the god of this world blinds the minds of those dying meaning the unbelieving, and we know this is not you. With this encouragement we could also consider that the spirit world is somehow involved with physical spiritual blindness. We ask the living God to rebuke all powers of the spirit world including natural not of God spiritual blindness such as a curse or evil spirits.
"And David was greatly distressed; for the people spoke of stoning him, because the soul of all the people was grieved, every man for his sons and for his daughters: but David encouraged himself in the LORD his God". 1 Samuel 30:6. We should celebrate that you like David realize your healing came from God and be sensitive to the leading of the same God that healed David.
We would also like to encourage you in your faith and remind you that our hope is in the Lord and that misfortune in the form of physically being blind should not overcome you because greater is he that is in you than he that is in the world. Remember that you had already said that you know that the Lord can heal you. Put your trust in the Father and make certain your salvation in him and in Jesus' name. It is only in Jesus' name that we have access to God.
John 14:6 Jesus said to him, I am the way, the truth, and the life. No one comes to the Father, except through me.
We will pray this with you as your compassionate brothers and sisters in Christ. We pray this in Jesus' name.