The Measurement of Elderly Volunteers’ Optic Nerve Sheath Diameters by Ocular Ultrasonography

Abstract

Background and objectives: The optic nerve is a component of the central nervous system, and the optic nerve sheath is connected to the subarachnoid space. For this reason, intracranial pressure (ICP) increases are directly transmitted to the optic nerve sheath. Knowing the normal optic nerve sheath diameter (ONSD) range in a healthy population is necessary to interpret this measurement as a sign of intracranial pressure in clinical practice and research. In this study, we aimed to determine the standard ONSD value in healthy adultsaged65 years of age or older who had not previously been diagnosed with a disease that could increase the ICP. Materials and Methods: The right and left ONSD values and ONSD differences were compared, according to the gender of the patients. The patients were divided into 3 groups, according to their age. The age groups were assigned as follows: Group 1: 65–74 years of age; Group 2: 75–84 years of age; and Group 3: 85 years of age or older. The ONSDs and the ONSD difference between the left and right eyes of Group 1, Group 2 and Group 3 were compared. Results: The study included 195 volunteers. The mean ONSD of both eyes was 4.16±0.69 mm, and the difference between the ONSD of the left and right eyes was 0.16±0.18 mm. There was no difference between genders in terms of right ONSD, left ONSD, mean ONSD and ONSD difference between the left and right eyes. There was no correlation between age and ONSD and ONSD difference. When the age groups and ONSD were compared, no difference was found between the groups. Conclusions: In conclusion, the ONSDs of both eyes do not vary with age in healthy adults aged65 years or older. ONSD does not vary between genders. The calculation of ONSD difference can be used to determine ICP increase.

High-resolution MRI assessment of optic nerve sheath diameter in adults: optic nerve sheath variation and a new diagnostic tool for intracranial hypertension

“…One previous study reported that in children, ONSD increases with age until the age of 10 years (7,21). Furthermore, some studies have found no difference in the ONSD between different ages in healthy adults (1,6,22). Our results were similar, whereby ONSD was not correlated with age in the participants in the control group.…”

“…An enlarged ONSD is regarded as an undisputed imaging sign that is suggestive of an elevated ICP (2–5). The anatomical connection between the optic nerve sheath and the subarachnoid space make the direct transmission of an ICP increase to the optic nerve sheath possible (6).…”

Relationship between internal carotid artery stenosis grade and optic nerve sheath diameter measured by transorbital ultrasonography

“…Yet, there is still no consensus on cut-off values in the detection and monitoring of increased ICP, which is the most common reason for ONSD measurement. 4 False positive and false negative results are mentioned in some studies investigating the usefulness of the transorbital ultrasonographic ONSD measurement in different clinical situations. [22][23][24][25] In a study conducted with 102 patients to investigate the relationship between ONSD values and increased ICP, false negative results were obtained in 9.6% and false positivity in 8.2% of cases.…”

“…6 In elderly volunteers, the right-left ONSD difference was 0.15 ± 0.17 mm in women and 0.18 ± 0.19 mm in men. 4 Therefore, there appears to be a difference between the right and left ONSDs not only in patients but also in healthy adults, and this difference may increase in the presence of an intracranial event. In the present study, the right-left ONSD difference was 0.05 ± 0.05 mm in the patients with no grade difference between the right and left ICA, 0.55 ± 0.32 mm in those with a single-grade difference, and 0.78 ± 0.39 mm in those with a twograde difference.…”

“…Studies comparing these techniques have shown that the transorbital ultrasonographic measurement of the ONSD is an easily applicable method with high accuracy for the noninvasive diagnosis of increased ICP. [2][3][4] Patients with glaucoma, impaired ophthalmic anatomy due to a tumor or trauma, endocrinopathy, electrolyte disturbances, or using drugs affecting ICP, are generally excluded from such evaluations 3,[5][6][7][8] in order to eliminate the confounding effects of extrinsic factors on ONSD. Some studies revealed that internal carotid artery (ICA) stenosis may by associated with ocular blood flow abnormalities.…”