Glaucoma in patients with shunt-treated normal pressure hydrocephalus

Area of Science:

• Ophthalmology
• Neurosurgery
• Neurology

Background:

• Normal tension glaucoma (NTG) may be linked to pressure gradients at the lamina cribrosa.
• Shunt-treated normal pressure hydrocephalus (NPH) offers a model to study intracranial pressure (ICP) effects on glaucoma.
• Understanding ICP dynamics is crucial for managing NPH and preventing secondary conditions like NTG.

Purpose of the Study:

• To estimate the prevalence of NTG in patients with shunt-treated NPH.
• To assess the relationship between ICP changes (protection and exposure periods) and NTG development.
• To determine if ICP fluctuations are risk factors or protective for glaucoma in NPH patients.

Main Methods:

• Analysis of data from patients who underwent ventriculoperitoneal (VP) shunting for NPH.
• Ophthalmic evaluation for NTG in patients with over 6 months follow-up and no confounding pathologies.
• Calculation of optic nerve exposure to trans-lamina cribrosa pressure gradients.

Main Results:

• NTG prevalence was approximately 40-fold higher in shunt-treated NPH patients compared to the general elderly population (p < 0.001).
• A longer ICP 'protection period' was associated with lower NTG risk (p = 0.033).
• Increased ICP decrease multiplied by exposure duration significantly correlated with NTG development (p = 0.048).

Conclusions:

• The duration of optic nerve exposure to lowered ICP is a critical risk factor for NTG in shunt-treated NPH.
• Informing NPH patients about glaucoma risk prior to CSF shunting is essential.
• Further longitudinal studies are needed to quantify tolerated ICP decrease durations.