Study of Corneal Biomechanics in Glaucoma Patients Using Brillouin Microscopy

This study explores the biomechanical properties of the cornea in patients with glaucoma using a novel, non-contact imaging technique called Brillouin microscopy. The technology allows in vivo assessment of tissue stiffness without physical perturbation, potentially offering new insights into glaucoma risk and response to therapy.

The study includes two parts: a cross-sectional comparison between patients with normal- and high-tension glaucoma and healthy controls, and a longitudinal analysis of biomechanical changes following IOP-lowering treatment with either prostaglandin analogs or beta blockers.

The goal is to determine whether corneal biomechanics can serve as a biomarker for glaucoma susceptibility and progression, and to evaluate the feasibility of integrating Brillouin imaging into clinical glaucoma care.

• Prostaglandin Analogue -Containing IOP-Lowering Therapy (Drug), also known as Latanoprost, Travaprost, Bimatoprost: Subjects with glaucoma may be prescribed prostaglandin analogs as part of their clinical care. This group will be observed longitudinally to assess changes in corneal biomechanics.
• Beta Blocker (Drug), also known as Timolol: Subjects with glaucoma may be prescribed topical beta blockers as part of their clinical care. This group will be observed longitudinally to assess changes in corneal biomechanics.
• Brillouin Microscopy (Device), also known as Brillouin Imaging: Brillouin microscopy is a non-contact optical imaging method used to assess the biomechanical properties of the cornea in vivo with three-dimensional resolution. It will be used to evaluate corneal stiffness in all study subjects.

Primary outcomes

• Change in Corneal Biomechanical Modulus [Baseline, 3 weeks, and 6 weeks]: Brillouin microscopy will be used to measure the corneal modulus of elasticity. The primary outcome is the change in corneal stiffness (Brillouin shift in MHz) across time points in subjects treated with prostaglandin analogs versus beta blockers, and between groups at baseline (NTG, HTG, controls).

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

\- Age 18 years or older

Diagnosis of primary open angle glaucoma (POAG) or no history of glaucoma (for controls)

Open angle on gonioscopy (Shaffer grade 3 or 4)

Best-corrected visual acuity of 20/25 or better

Refractive error between +3.00 and -5.00 diopters

No prior use of topical glaucoma medications

Diagnosis of:

High Tension Glaucoma (IOP ≥ 22 mmHg on 3 visits)

Normal Tension Glaucoma (IOP ≤ 21 mmHg on 3 visits)

OR age-matched control with normal optic nerve and visual fields

Exclusion Criteria:

Corneal abnormalities or conditions interfering with Brillouin or applanation tonometry

Retinal diseases affecting RNFL (e.g., macular traction)

History of ocular surgery or laser

Diagnosis of diabetes

History of uveitis

History of prolonged steroid use

Neurodegenerative or systemic diseases (e.g., multiple sclerosis, Alzheimer's, Parkinson's, schizophrenia)

Unreliable visual fields

Contraindications to beta blockers (e.g., bradycardia, severe pulmonary disease)

Moderate to severe glaucoma (per Hodapp-Anderson-Parrish criteria)

History of contact lens use

Low blood pressure

• Osamah Saeedi, MD, Principal investigator, University of Maryland, Baltimore

NIH grants: R21EY035483