Current RMA Instruments:
| 95 of 2025 | |
| 96 of 2025 |
Changes from previous Instruments:
ICD Coding:
- ICD-10-AM Codes: G03.1
Brief description
Optochiasmatic arachnoiditis is a rare condition involving chronic inflammation of the arachnoid membrane (one of the protective layers of the meninges) that surrounds the optic chiasm and the intracranial portions of the optic nerves. The optic chiasm itself is an X-shaped structure at the base of the brain where the optic nerves from each eye meet and partially cross over.
This persistent inflammation leads to fibrosis and the formation of adhesions, which can damage these structures and typically results in progressive loss of vision.
Confirming the diagnosis
The diagnosis of optochiasmatic arachnoiditis is difficult to establish, as symptoms and early clinical findings can be non-specific. It may be suspected based on clinical presentation (particularly progressive visual impairment) and MRI imaging findings suggesting inflammation or scarring around the optic chiasm and optic nerves.
In some cases, direct visualisation during neurosurgical exploration may be required to confirm the diagnosis. Ophthalmologists and neurosurgeons are the relevant medical specialists to confirm this diagnosis.
Additional diagnoses covered by SOP
- Nil
Conditions not covered by SOP
- Optic neuritis #
# non-SOP condition
Clinical onset
Because symptoms and examination findings are often non-specific, clinical onset generally corresponds to the time when the diagnosis was first confirmed, usually through imaging and specialist assessment. Once the diagnosis is confirmed, onset may be backdated to the earliest evidence of symptoms attributable to this condition.
Clinical worsening
Optochiasmatic arachnoiditis is difficult to treat, and progressive deterioration in vision is common due to ongoing inflammation and fibrosis.
Assessing whether worsening has occurred beyond the expected course of the disease requires evaluation by a specialist- usually an ophthalmologist or neurosurgeon- because progression may reflect the natural history rather than an avoidable clinical deterioration.