Assessment of Intraocular Pressure Using Three-Dimensional MR Elastography in Ophthalmologically Normal Individuals.

BACKGROUND

Elevated intraocular pressure (IOP) is a major risk factor for glaucoma, and accurate assessment is required for diagnosis and management. Goldmann applanation tonometry (GAT) requires corneal contact, whereas non-contact tonometry (NCT) is susceptible to ocular geometry.

PURPOSE: To evaluate three-dimensional MR elastography (3D-MRE) as a non-invasive method for IOP assessment.

STUDY TYPE: Prospective.

SUBJECTS: Twenty-nine healthy volunteers (13 females and 16 males, median age: 33).

FIELD STRENGTH/SEQUENCE: Phase-contrast spin-echo echo planar MRE at 3.0 T.

ASSESSMENT: IOP measured by GAT (IOPGAT) and NCT (IOPNCT) was obtained. Ocular geometry parameters (central corneal thickness [CCT], mean keratometry [Km], axial length [AL], anterior chamber depth [ACD], and lens thickness [LT]) were measured by optical biometry. The first 10 subjects underwent repeated MRE at 60, 90, and 120 Hz to assess test-retest repeatability, and 90 Hz was used in subsequent acquisitions. Three readers (S.Y., G.Z., and Z.Y., with 12, 3, and 3 years of experiences in MRE, respectively) independently assessed shear stiffness (SS) of the anterior segment and whole eye to evaluate test-retest repeatability and inter-/intra-observer agreement.

STATISTICAL TESTS: Wilcoxon signed rank test; multivariable regression; intraclass correlation coefficient (ICC); Spearman's correlation; Significance level: p < 0.05.

RESULTS

SS@90 Hz of the anterior segment (SS-AS@90 Hz) demonstrated excellent repeatability and inter-/intra-observer agreement (all ICC ≥ 0.889). IOPGAT demonstrated a stronger correlation with SS-AS@90 Hz (r = 0.64) than with IOPNCT (r = 0.59). Multivariable regression identified SS-AS@90 Hz (β = 0.53) and IOPNCT (β = 0.40) as independent predictors of IOPGAT, collectively explaining 58.3% of the variance. No correlation between SS-AS@90 Hz and CCT (p = 0.10), Km (p = 0.67), ACD (p = 0.90), or LT (p = 0.82) was found, while a significant correlation with AL (r = 0.02) was observed.

DATA

CONCLUSION

SS-AS@90 Hz was identified as a robust biomarker for predicting IOP, independent of most ocular geometric parameters.

EVIDENCE LEVEL: 1.

TECHNICAL EFFICACY: 1.