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Achmed Pircher,1,2 Albert Neutzner,3 Margherita Montali,4 Andreas Huber,5 Hendrik PN Scholl,2,6 Jatta Berberat,7 Luca Remonda,7 Hanspeter E Killer3 1Department of Neuroscience/Ophthalmology, Uppsala University, Uppsala, Sweden; 2Department of Ophthalmology, University Hospital Basel & University Basel, Basel, Switzerland; 3Department of Biomedicine, University Hospital Basel & University Basel, Basel, Switzerland; 4Department of Ophthalmology, San Bassiano Hospital, Bassano del Grappa, Italy; 5Department of Medicine, Private University of the Principality of Lie Triesen, Triesen, Liechtenstein; 6Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland; 7Department of Neuroradiology, Cantonal Hospital Aarau, Aarau, SwitzerlandCorrespondence: Achmed PircherDepartment of Neuroscience/Ophthalmology, Uppsala University, Uppsala, SwedenTel +46 76 496 37 51Email achmed.pircher@gmail.comObjective: To report on the lipocalin-type prostaglandin D synthase (L-PGDS) concentrations in the cerebrospinal fluid (CSF) of the perioptic and lumbar subarachnoid space (SAS) in patients with radiologically proven optic nerve (ON) sheath compartmentation presenting as normal-tension glaucoma (NTG).Methods: Retrospective biochemical analysis of CSF in thirteen patients with ON sheath compartmentation presenting as NTG (four females, mean age 70± 8 years). CSF was sampled from the SAS of the ON during ON sheath fenestration for ON sheath compartmentation and from the lumbar SAS at the time of lumbar puncture. Nephelometry was used for the quantification of L-PGDS and albumin concentration. Albumin was measured in order to assess the amount of contamination with serum in the CSF samples taken from the ON SAS. Main outcome measures were L-PGDS concentrations in the CSF of the perioptic and lumbar SAS.Results: Mean L-PGDS concentration was 24± 8 mg/L in the lumbar SAS compared to 33± 27 mg/L without correction of serum contamination and 45± 39 mg/L after correction of serum contamination in the perioptic SAS. The difference between the lumbar and the perioptic SAS was statistically significant (P=0.0047 without correction of serum contamination, P=0.0002 with correction of serum contamination; Mann–Witney U-test).Conclusion: This study demonstrates a concentration gradient of L-PGDS levels within the CSF with a statistically significant higher concentration in the compartmentalized perioptic SAS compared to that in the lumbar SAS. Biochemical changes in the perioptic SAS might be involved in the pathophysiology in NTG patients with ON sheath compartmentation.Keywords: lipocalin-type prostaglandin D synthase, cerebrospinal fluid, optic nerve sheath compartment syndrome, normal-tension glaucoma, optic nerve

Permanent visual loss is a devastating yet preventable complication of cryptococcal meningitis. Early and aggressive management of cerebrospinal fluid pressure in conjunction with antifungal therapy is required. Historically, the mechanisms of visual loss in cryptococcal meningitis have included optic neuritis and papilloedema. Hence, the basis of visual loss therapy has been steroid therapy and intracranial pressure lowering without clear guidelines. With the use of high-resolution magnetic resonance imaging of the optic nerve, an additional mechanism has emerged, namely an optic nerve sheath compartment syndrome (ONSCS) caused by severely elevated intracranial pressure and fungal loading in the peri-optic space. An improved understanding of these mechanisms and recognition of the important role played by raised intracranial pressure allows for more targeted treatment measures and better outcomes. In the present case series of 90 HIV co-infected patients with cryptococcal meningitis, we present the clinical and electrophysiological manifestations of Cryptococcus-induced visual loss and review the mechanisms involved.