Dear Editor,

I read with great interest your extremely valuable article. I have been working in the field of PTC and optic nerve sheath decompression for about 12 years now and my clinical experience very much supports the findings in your work. There are variable degrees of papilledema in the same patient with the same level ICP and variable responses of patients to medical therapies decreasing the ICP, with some patients responding and some patients needing surgery. There are patients who respond to CSF shunting procedures and those who do not, leading to the indication of optic nerve sheath decompression.

I proposed a new theory called the pressure dissociation theory, which suggests a pressure dissociation between the ICP and the subarachnoid pressure of the optic nerve due to the presence of a valve mechanism related to subarachnoid trabeculations. This may be a crucial factor in determining the response to decompressing the central compartment.

I also suggested that PTC may be classified into communicating and non-communicating according the degree of communication between the subarachnoid space of the optic nerve and the central compartment.

The clinical variability in this disease suggests a great variability in the communication that may be very important in determining who will respond to therapy.

I suggest that this paper should have another phase studying cadavers having PTC with and without visual loss and I think that this may be different from the normal population.

Your work opens the way for more understanding of visual loss in papilledema due to PTC .

Sherif AK Amer
MD ophthalmology
Cairo University
Consultant neuroophthalmologist
National Eye Center
Egypt