Adduction induces large optic nerve head deformations in subjects with normal-tension glaucoma

• Published in: British journal of ophthalmology Vol. 108; no. 4; pp. 522 - 529
• Main Authors: Chuangsuwanich, Thanadet, Tun, Tin A, Braeu, Fabian A, Wang, Xiaofei, Chin, Zhi Yun, Panda, Satish K, Buist, Martin, Milea, Dan, Strouthidis, Nicholas, Perera, Shamira, Nongpiur, Monisha Esther, Aung, Tin, Girard, Michael J A
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.04.2024; BMJ Publishing Group LTD
• Subjects: Biomechanics; Cerebrospinal fluid; Cross-Sectional Studies; Deformation; Eye movements; Glaucoma; Glaucoma, Open-Angle - diagnosis; Humans; Intraocular Pressure; Low Tension Glaucoma - diagnosis; Optic Disk; Optic Nerve; Optics; Tomography; Tomography, Optical Coherence; United States > US; Singapore; Glaucoma; Optic Nerve
• ISSN: 0007-1161; 1468-2079; 1468-2079
• DOI: 10.1136/bjo-2022-322461

PurposeTo assess intraocular pressure (IOP)-induced and gaze-induced optic nerve head (ONH) strains in subjects with high-tension glaucoma (HTG) and normal-tension glaucoma (NTG).DesignClinic-based cross-sectional study.MethodsThe ONH from one eye of 228 subjects (114 subjects with HTG (pre-treatment IOP≥21 mm Hg) and 114 with NTG (pre-treatment IOP<21 mm Hg)) was imaged with optical coherence tomography (OCT) under the following conditions: (1) OCT primary gaze, (2) 20° adduction from OCT primary gaze, (3) 20° abduction from OCT primary gaze and (4) OCT primary gaze with acute IOP elevation (to approximately 33 mm Hg). We then performed digital volume correlation analysis to quantify IOP-induced and gaze-induced ONH tissue deformations and strains.ResultsAcross all subjects, adduction generated high effective strain (4.4%±2.3%) in the LC tissue with no significant difference (p>0.05) with those induced by IOP elevation (4.5%±2.4%); while abduction generated significantly lower (p=0.01) effective strain (3.1%±1.9%). The lamina cribrosa (LC) of HTG subjects exhibited significantly higher effective strain than those of NTG subjects under IOP elevation (HTG: 4.6%±1.7% vs NTG: 4.1%±1.5%, p<0.05). Conversely, the LC of NTG subjects exhibited significantly higher effective strain than those of HTG subjects under adduction (NTG: 4.9%±1.9% vs HTG: 4.0%±1.4%, p<0.05).ConclusionWe found that NTG subjects experienced higher strains due to adduction than HTG subjects, while HTG subjects experienced higher strain due to IOP elevation than NTG subjects—and that these differences were most pronounced in the LC tissue.