Ultrasonography can be used in the diagnosis and monitoring of neurological diseases of the eye in 3 main ways: 1. It can measure the diameter of the optic nerve sheath to detect increased intracranial pressure earlier than papilledema by examining for swelling above cutoff values. 2. It aids in diagnosing visual loss conditions like central retinal artery occlusion and temporal arteritis by examining blood flow in orbital vessels using Doppler modes. 3. It can identify pseudopapilledema causes like optic disc drusen which appear as calcific dispositions on the optic nerve head.

1. Use of Ultrasonography in
Neurological diseases of the eye:
Dr.Roopchand PS
Senior Resident Academic
Department of Neurology

2. Introduction:
• Settings used in USS eye
– B-mode – transmit frequency 14 MHz, mechanical
index (MI) = 0.23, single focal zone at 2.5 cm,
bandwidth 74 dB;
– C-mode – transmit frequency 10 MHz, MI = 0.23,
color scale optimized for low velocities, no wall
filter
– pw-Mode – transmit frequency 2 MHz, MI = <0.23
(<0.44*) .

3. • During the examination the patient lies in
supine position with the eyes closed.
• A layer of acoustic gel is applied to the closed
lids, the transducer is placed on the upper and
slightly lateral eye-lids with the examiner’s
hand resting on the orbital margin to minimize
pressure on the globe.

5. ICP Monitoring:
• Raised Intracranial Pressure (ICP) is a dreaded
complication of neurological disease.
• Invasive measurement by an intraventricular
or intra-parenchymal catheter is the gold
standard.
• It may not be feasible in a heterogenous group
of medical patients.

6. • The optic nerve sheath is an anatomical
extension of the duramater
• The subarachnoid space around the optic
nerve is continuous with the intracranial
subarachnoid space.
• Any pressure rise within the intracranial
compartment impacts on the optic nerve head
as swelling of the optic disc and papilledema.

7. • Requiring a skilled observer for precise
identification.
• May develop late or may evolve.
• Dilatation of the optic nerve sheath has been
shown to be a much earlier manifestation of
ICP rise.
• B Mode USS can be used to measure optic
nerve sheath.

8. • Using cut-off values of 4.6 mm for females,
and 4.8 mm for males-high level of sensitivity
and specificity for the diagnosis of intracranial
hypertension as evident on CT or MRI imaging.
• Can be used for early detection aswell as
monitoring of ICP.

10. Papilledema
The mean depth measurements ranged from 0.68 to 2.01 mm (1.17 +/-
0.38 mm)

11. Vascular diagnostics:
• It can greatly aid in the diagnosis of visual loss
due to CRAO and Temporal Arteritis.
• B mode scan, Spectral Doppler with colour
mode are used.
Orbital vessel Mean ± SD Blood Flow, cm/s (Range)
Central retinal artery 10.3 ± 2.1 (6.4-17.2)
Central retinal vein 2.9 ± 0.73 (1.9-5.4)
Ophthalmic artery 31.4 ± 4.2 (23.5-39.8)
Posterior ciliary artery 12.4 ± 4.8 (1.4-22.7)

12. Normal:

13. • CRAO a hyperechoic structure might be
depicted in the optic nerve head, representing
a fresh cholesterol embolus - termed “spot
sign

15. Pseudopapilledema:
• A common cause for pseudopapilledema are
optic disc drusen.
B-mode sonography: calcific dispositions in the optic nerve head representing optic
disc drusen. (b) Fundoscopy: nasally located superficial drusen, blurred rim of optic
disc, optic disc edema and hyperemia