Thank you for the additional information. It is very helpful.
There are 3 possibility for his vision loss.
1) Cancer associated retinopathy - This is a retinal degeneration caused by a cross-reactivity with certain cancers and they eye. This is common associated with lung cancers. In the early stages, it may be difficult to tell on exam, but there are specialized testing of electrical activity of the brain that can differentiate it (ERG - electroretinogram).
2) Optic nerve damage from the intrathecal methorexate - The optic nerve carries the signals from the eye to the brain. The optic nerve could have been damaged due to direct contact with the chemotherapy drugs (methotrexate).
3) Damage to the visual pathways - The signals go through the nerve, then back to different pathways and finally to the part of the brain that process the information. Possibly, the lymphoma could have damage part of this pathway. This usually causes a focal visual field defect, such as not seeing half of the vision or only a quarter of the visual field.
I believe he needs to be examined by an ophthalmologist
. He will check his current vision and assess the function of the optic nerve. Likely perform an automated visual field test
and look in the back.
I suspect it could to optic nerve damage from the methotrexate. It that is the case, then you will need to discuss with your oncologist regarding risk/benefits of continuing it. Treatment for #1 is the treat the underlying cancer. For #3, CT scan may help to visualize any masses that could be affecting the visual pathways.
Remember to press the accept button. It was a pleasure helping you with your question today. I wish the best for you and your husband and continued strength to help you through this. Feel free to ask any additional questions.