Three-dimensional anatomy and dynamic changes of the conjunctival fornix assessed by high

Abstract Background To characterise the three-dimensional (3D) anatomy and dynamic changes of the conjunctival fornix across different gaze positions using high-resolution magnetic resonance imaging (MRI). Subjects/methods Three eyes of three healthy adult female volunteers without ocular or systemic disease, prior ocular surgery, or ocular surface pathology. A scleral buckling sponge was inserted into the superior and inferior conjunctival fornices to create an implant-induced forniceal space (IFS). High-resolution orbital MRI was performed during primary gaze, upgaze, downgaze and eyelid closure. IFS volume, surface area, fornix depth (FD) and cornea-fornix (C-F) distance were quantified and compared across positions. Results At primary gaze, the superior fornix showed larger IFS volume and surface area than the inferior fornix, though differences were not significant. Both superior and inferior FD and C-F distance varied with gaze. Superior FD was shortest at downgaze and longest at upgaze and eyelid closure, while inferior FD was shortest at primary gaze and longest at eyelid closure. Superior C-F distance was shortest during eyelid closure, whereas inferior C-F distance was longest at primary gaze and shortest at downgaze. Conclusions This first MRI-based 3D quantitative assessment demonstrated gaze-dependent variability of the conjunctival fornix. The fornix should be regarded as a dynamic rather than static structure, with potential implications for ocular surface disease evaluation, surgical planning and the design of fornix-based implants. Introduction The conjunctival fornix is a blind-ended anatomical pouch located between the bulbar conjunctiva covering the anterior sclera and palpebral conjunctiva lining the inner surface of the eyelids. This curved junction forms two fornices, superior and inferior, which serve as flexible reservoirs accommodating the dynamic movements of the globe and act as buffers that minimise excessive friction between the eyelid and ocular surface [1]. The conjunctival fornix is continuous with the conjunctival sac and its elasticity and spatial capacity render it an anatomically distinct and functionally critical component of the ocular surface. Disease conditions involving the conjunctival sac are diverse, including symblepharon, foreign bodies, trauma-related disease status [2,3,4]. In advanced cases, accurate assessment of forniceal anatomy is essential for surgical planning and prognosis, as alterations in forniceal anatomy may affect ocular surface integrity and ocular motility [5, 6]. However, precise evaluation based solely on slit-lamp examination is challenging. Although several methods have been proposed to measure fornix depth, most provide only planar and static information [7,8,9,10]. The conjunctival cul-de-sac has also recently gained attention as a target site for sustained-release ocular drug delivery systems known as cul-de-sac implants. Several devices, such as bimatoprost ocular insert (HELIOSTM, Abbvie Inc., IL, USA), dexamethasone implant (DextenzaTM, Ocular Therapeutix Inc., MA, USA), hydroxypropyl cellulose insert (Lacrisert®, Aton Pharma Inc., Lawrenceville, NJ, USA), have been developed to be placed in the conjunctival fornix to release drugs [11,12,13,14]. These devices aim to improve bioavailability, reduce drug administration frequency and enhance patient compliance. However, discomfort, foreign body sensation, device migration and corneal complications limit their widespread adoption [15,16,17]. Many of these challenges can be attributed to suboptimal anatomical conformity between the device and the fornix, underscoring the need for precise anatomical data to guide implant design. Despite its importance, the three-dimensional (3D) anatomy of the conjunctival cul-de-sac and its positional variability during different eye movements remain underexplored. Existing clinical assessments, such as slit-lamp examinations or the use of fornix depth measurers (FDMs), offer limited static and planar information [18]. However, the fornix is a dynamic structure that undergoes changes in depth, volume and curvature depending on gaze direction and eyelid position. These dynamic properties can affect the outcomes of ocular surgery, prosthetic fitting and therapeutic device implantation. Magnetic resonance imaging (MRI) offers a non-invasive approach for high-resolution visualisation of ocular structures under physiological conditions and enables assessment of dynamic anatomical changes [19]. In this study, we investigated the three-dimensional morphology of the superior and inferior conjunctival fornices using high-resolution orbital MRI. We specifically quantified fornix depth and cornea–fornix distance across four eye positions—primary gaze, upward gaze, downward gaze and eyelid closure—to provide novel insights into the dynamic anatomy of the conjunctival fornix. Materials and methods Participants Five healthy volunteers were recruited in this single-centre cross-sectional study. Participants with contraindications for MRI, strabismus, ocular motility disorders, ocular or systemic diseases, prior ocular surgery, long-term ocular medication use, trauma, or radiation exposure were excluded. Patients with ocular surface pathologies, including symblepharon, conjunctivochalasis, or severe dry eye disease, were also excluded. Of the five participants, two were excluded because of a foreign body sensation caused by the forniceal insert. Thus, three eyes from three healthy subjects were included in the final analysis. This study was approved by the Institutional Review Board of Hanyang University Hospital (HYUH 2022-01-039-003) and was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants. Study protocol After instillation of one drop of 0.5% proparacaine hydrochloride (Paracaine®, Hanmi Pharm., Seoul, Korea), a commercially available scleral buckling sponge (Style 506, Dutch Ophthalmic USA, Inc., NH, USA; 3 × 5 × 10 mm) was placed in the superior and inferior fornices of the left eye by an ophthalmologist (Y.J.K.), followed by insertion of a therapeutic contact lens (Acuvue Oasys®, Johnson & Johnson Vision, Jacksonville, FL, USA) to protect the cornea. To enhance visualisation and define a measurable space within the conjunctival fornices, the sponge was deliberately inserted, creating what we defined as the implant-induced forniceal space (IFS), which is the artificial space formed between the inner eyelid surface, ocular surface and implanted sponge (Fig. 1A, B). MRI images were then obtained in four eye positions: primary gaze, upward gaze, downward gaze and eyelid closure. The gaze targets were pre-marked and the participants practiced fixation before scanning. Each scan lasted less than 3 min, with 1-min breaks between gaze position changes. Imaging was performed in the left eye only to ensure consistency of measurement and optimal visualisation; the right eye was excluded due to suboptimal image quality of the fornix region. Pre-MRI clinical assessments included best-corrected visual acuity, tonometry, refraction, slit-lamp examination, dilated fundus examination, axial length measurement and eye-movement tests. MRI acquisition and preprocessing High-resolution T1-weighted images were acquired using a 3 T Siemens Prisma scanner (Siemens, Munich, Germany) at the Center for Neuroscience Imaging Research, Sungkyunkwan University. A 2D gradient-recalled echo sequence was applied in the sagittal plane using a 64-channel head coil (repetition time = 160 ms, echo time = 2.86 ms; flip angle = 80°, slice thickness = 1.5 mm; field of view = 220 × 220 mm², matrix = 320 × 320). MRI data were converted to NIfTI format using MRIcron (https://github.com/neurolabusc/MRIcron). Bias field correction and alignment of the central gaze image were performed using FSL tools (https://fsl.fmrib.ox.ac.uk/fsl/fslwiki) for consistent superimposition across gaze positions. Implant-induced forniceal space volume and surface area Volumetric measurements were conducted for the IFS, which is defined as the space artificially widened by the buckle sponge inserted within conjunctival fornices. The IFS is bound by the inner eyelid surface, outer ocular surface and apical border of the sponge. To enhance anatomical delineation, the intensity of the T1-weighted images was inverted, allowing for a clearer visualisation of structural boundaries. The sponge exhibited a uniform intensity value of 1 after inversion, which facilitated accurate segmentation of the IFS using ITK-SNAP software (version 3.6.0) (Fig. 1C–F). The volume and surface area of the IFS were estimated from the segmented images using MATLAB’s regionprops3 function, which calculates morphological properties based on voxel geometry. Surface area of the IFS was calculated by summing the surface contributions of the boundary voxels. Measurements were performed for both superior and inferior fornices. Fornix depth and cornea-fornix distance The fornix depth (FD) was defined as the length from the fornix apex to the most distant eyelid margin point, manually traced along the fornix curve by two ophthalmologists (Y. J. K. and J. S. K.) on sagittal MRI images (Fig. 2A). The cornea-fornix (C-F) distance, defined as the Euclidean distance from the corneal centre to the fornix apex, was similarly measured (Fig. 2B). Measurements were performed using a custom MATLAB script. Statistical analysis Kruskal-Wallis tests were used to compare IFS volume, IFS surface area, FD and C-F distance across the four gaze positions. Pairwise comparisons were performed using the Mann-Whitney U test. Statistical analysis was conducted using SPSS v29.0 (IBM, Chicago, IL, USA), with p < 0.05 considered as significant. Results Demographics and clinical characteristics Three eyes from three healthy female participants were included in the final analysis. Demographic data are presented in Table 1. The mean age was 41.7 ± 2.3 years (range, 39–44 years). The mean intraocular pressure was 18.3 ± 1.0 mmHg (range, 18–19 mmHg). All participants were myopic, with a mean spherical equivalent of –3.9 ± 2.7 D (range, –0.8 to –5.5 D) and a mean axial length of 24.5 ± 0.8 mm (range, 23.5–24.9 mm). Volume and surface area of implant-induced forniceal space Across all gaze positions, the volume and surface area of the superior IFS were greater than those of the inferior IFS. At primary gaze, the mean volume was 171.3 ± 23.6 mm³ for the superior IFS and 148.2 ± 46.5 mm³ for the inferior IFS (Table 2). Corresponding surface areas were 116.5 ± 18.4 mm² and 96.2 ± 45.9 mm², respectively (Table 2). However, no statistically significant differences were observed in volume or surface area between the superior and inferior fornices, or across different gaze positions (Table 2). Fornix depth FD varied significantly across gaze directions and is summarised in Table 3. Mean superior FD at primary gaze was 14.2 ± 1.0 mm. The superior FD was shortest during downgaze (13.5 ± 1.7 mm) and significantly increased during upgaze (14.8 ± 1.7 mm, p = 0.02) and eyelid closure (14.8 ± 2.6 mm, p = 0.01). For the inferior fornix, the mean depth was shortest at primary gaze (7.4 ± 1.3 mm) and longest at eyelid closure (8.6 ± 2.9 mm), with a statistically significant difference (p = 0.01). Cornea-fornix distance Similar to FD, the C–F distance also showed significant gaze-dependent variability (Table 3). The mean superior C-F distance at the primary gaze was 19.7 ± 1.9 mm. The superior C-F distance was shortest at eyelid closure (11.1 ± 1.7 mm, p < 0.01 vs. other positions). For the inferior fornix, the shortest distance was observed during downgaze (9.6 ± 1.1 mm, p < 0.01 vs. other positions), whereas the longest distance occurred at primary gaze, which was significantly greater than at other positions (p < 0.01). Discussion To the best of our knowledge, this is the first study to characterise the 3D anatomy of the conjunctival fornix and its dynamic changes in different eye positions. By quantifying FD, C-F distance and IFS volume and surface area across the primary gaze, upward gaze, downward gaze and eyelid closure, we provide novel insights into a region that has traditionally been regarded as a static space with little clinical significance. This paradigm shift from a static to a dynamic anatomical concept has important implications for both clinical evaluation and device design. Despite the insertion of sponges with identical volumes, the superior IFS demonstrated a larger volume and surface area than the inferior IFS. This suggests that the superior fornix may exhibit greater compliance and flexibility, thereby serving as a principal tear reservoir [7]. In a disease status, superior fornix involvement would likely lead to more pronounced clinical consequences and render it a critical structure for reconstructive surgery [5,6,7, 20]. From a therapeutic perspective, the superior fornix may also provide more favourable site than the inferior fornix for accommodating implants of a given size. Moreover, because IFS volume and surface area did not differ significantly across gaze positions in our dataset, these findings suggest that physiologic eye movements alone may not impose sufficient deformation to measurably compress a forniceal insert. Notably, FD and C-F distance exhibited gaze-dependent variability, reflecting the dynamic nature of the fornix. The superior FD was shortest during downgaze and significantly increased during upgaze and eyelid closure. The inferior FD was shortest at primary gaze and significantly increased during eyelid closure. These findings suggest that the positional behaviour of fornix-based implants may vary depending on eye position and eyelid state [17]. Similarly, the superior C-F distance was shortest during eyelid closure, likely reflecting the combined effects of lid closure and Bell’s phenomenon, which brings the fornix apex closer to the corneal surface. This finding suggests a potential risk of closer implant-cornea proximity during eyelid closure, which may be relevant during sleep [21, 22]. In contrast, the inferior C-F distance was longest at primary gaze and shortest at downgaze, further highlighting the mechanical interplay between the globe and eyelids. Collectively, these results may provide preliminary framework for assessing device safety with respect to eye position and for guiding surgical strategies in fornix reconstruction. Clinically, diseases that shorten the fornix, such as ocular cicatricial pemphigoid and symblepharon, have been graded primarily on slit-lamp based assessments of horizontal involvement [23, 24]. More recent grading systems, such as that proposed by Kheirkhah and colleagues, incorporate fornix length and width to guide surgical planning and graft sizing, leading to improved outcomes [25]. However, these approaches remain restricted to planar or subjective evaluations. Our study demonstrates that MRI-based quantification provides an objective, reproducible and 3D assessment of fornix anatomy, while capturing dynamic changes not detectable with conventional methods [9, 18, 26, 27]. As the fornix plays a key role in tear distribution and ocular motility, improved understanding of its dynamics may enhance surgical strategies and guide the design of fornix-based devices [1, 6, 11]. Unlike our expectations, in our MRI-based study, the mean superior FD at primary gaze was 14.2 mm, which was shorter than those reported in FDM-based studies: 15.3 mm in healthy South Asians and 15.6 mm in healthy White Caucasians [9, 18]. Similarly, the inferior FD in our study (7.4 mm) was shorter compared to those reported by Khan et al. and Jutley et al. (both 10.9 mm) [9, 18]. These discrepancies may be attributed to methodological differences. In our study, the inserted buckling sponge expanded the fornix but did not increase its anatomical length. In contrast, the FDM may have increased the measured FD by mechanically stretching the fornix, as the device is often pushed all the way to the innermost corner of the fornix by the examiner during use. Moreover, FD measurements using the FDM may be overestimated, as the device must be slightly lifted to avoid corneal contact and to ensure clear visibility of the scale. Populations or sex specific anatomic variations could also be a contributing factor, as previous normative studies with South Asian, White Caucasian, Turkish and Asian Chinese populations consistently reported that conjunctival fornix depth decreases with age and is generally smaller in females than males [9, 18, 26, 27]. (Supplementary Tables 1, 2) Ethnic variation, likely linked to craniofacial and orbital morphology, has been proposed, but absolute fornix depth values appear broadly comparable across populations. Recent Chinese data by Tan et al. also reported no significant differences when compared with Caucasian, South Asian and Turkish datasets [9, 18, 26, 27]. Thus, age and sex seem to be stronger determinants of FD than ethnicity, although population-specific normative datasets remain important for accurate interpretation. In this study, all participants were Korean women in their 40 s, resulting in reduced cohort heterogeneity but limiting generalisability. Future large-scale normative studies including broader age ranges and both sexes of South Korean ethnicity would be helpful. Nevertheless, because age-related reductions in fornix depth are more pronounced after 50–60 years, the gaze-dependent patterns observed in this cohort may still provide meaningful reference data [9, 18, 26, 27]. Beyond demonstrating the feasibility of MRI-based assessment of fornix dynamics, this study suggests several directions for technical development. The imaging workflow and segmentation process could be further refined and potentially automated. While fully automated fornix quantification is not yet available, recent MRI studies of adjacent ocular structures—such as the eyeball, optic nerve and orbit—show that semi-automated morphometric extraction is achievable [28,29,30]. These precedents, together with our findings, suggest the possibility of automated fornix-specific morphometry, particularly with high-resolution ocular MRI and standardised gaze registration. However, given the thin and deformable nature of the fornix, a semi-automated landmark- or contour-based approach may be a more realistic initial step. In addition, the development and validation of such methods will require larger multicentre datasets to improve robustness, clinical applicability and generalisability. Furthermore, MRI-derived anatomical data may be integrated with computational modelling to improve the design of fornix-based implants and to predict implant-fornix interactions. In ophthalmology, finite element and computational fluid dynamics approaches have already been used to connect anatomy, mechanics and device behaviour. For example, dynamic MRI has been combined with finite element modelling to estimate optic nerve head strain during eye movements [31,32,33,34,35]. In the implant field, computational modelling of glaucoma drainage devices has demonstrated that geometry, flow resistance, insertion angle and tissue interaction significantly influence device performance [36, 37]. These precedents suggest that future fornix imaging could be used not only descriptively, but also predictively. Patient-specific MRI-derived fornix geometry may provide the basis for finite element or fluid-structure models of implant-fornix interaction in the future. Such models could help optimise implant design, identify configurations prone to focal compression or instability and improve preclinical evaluation before broader clinical application. Our study has several limitations. The small sample size, along with the inclusion of a single ethnicity and sex cohort, limits the generalisability of the findings. Additionally, sponge insertion, though necessary for MRI visualisation, may have altered the native fornical configuration; its stiffness, shape and compressibility could have affected expansion patterns. Thus, the present results likely represent sponge-expanded rather than purely native anatomy. Future studies involving larger and more diverse populations, imaging approaches that reduce or avoid artificial expansion, will be important to validate and extend these findings. In conclusion, this proof-of-concept study demonstrates gaze-dependent forniceal configuration and that high-resolution MRI can be used to quantify its anatomy. Although the findings should be interpreted in the context of a small cohort and sponge-expanded anatomy, they provide a basis for future studies of fornix morphology and for imaging-based evaluation of diseased fornix and fornix-targeted devices. Summary What is known about this topic - The conjunctival fornix plays an important role in tear distribution, ocular surface protection and ocular device placement. - Existing clinical assessments of the fornix mainly provide static and planar measurements. - The three-dimensional anatomy and dynamic changes of the conjunctival fornix during eye movement remain poorly understood. What this study adds - High-resolution MRI enabled three-dimensional visualisation and quantitative assessment of the conjunctival fornix - Fornix depth and cornea-fornix distance showed significant gaze-dependent changes - These findings may help improve the evaluation of fornix disorders and guide the design of the fornix-based ocular implants and drug delivery devices. Data availability The datasets generated or analyzed during the current study are not publicly available due to patient privacy and institutional restrictions, but are available from the corresponding author on reasonable request. References Dean AM. Physiology of the conjunctival sac. J Iowa State Med Soc. 1951;41:459–60. Aslan Katircioglu Y, Kaderli A, Singar Ozdemir E, Ornek F. Clinical results of the use of amniotic membrane transplantation alone or in combination with adjuvant therapies in conjunctival fornix reconstruction. Turk J Ophthalmol. 2022;52:237–45. Kim YJ, Kim J, Choung H, Kim MK, Wee WR. Conjunctival granuloma with necrosis associated with exposed suture in upper double lid masquerading as ocular surface squamous neoplasia: a case report. BMC Ophthalmol. 2017;17:55. Suh IS, Yang YM, Oh SJ. Conjunctival cul-de-sac reconstruction with radial forearm free flap in anophthalmic orbit syndrome. Plast Reconstr Surg. 2001;107:914–9. Cheng AM, Yin HY, Chen R, Tighe S, Sheha H, Zhao D, et al. Restoration of fornix tear reservoir in conjunctivochalasis with fornix reconstruction. Cornea. 2016;35:736–40. Cheng AMS, Mead OG, Tighe S, Tseng SCG. Fornix deepening reconstruction in conjunctivochalasis surgery. Taiwan J Ophthalmol. 2023;13:49–54. Huang Y, Sheha H, Tseng SC. Conjunctivochalasis interferes with tear flow from fornix to tear meniscus. Ophthalmology. 2013;120:1681–7. Kang Y, Li S, Liu C, Liu M, Shi S, Xu M, et al. A rabbit model for assessing symblepharon after alkali burn of the superior conjunctival sac. Sci Rep. 2019;9:13857. Khan IJ, Ghauri AJ, Hodson J, Edmunds MR, Cottrell P, Evans S, et al. Defining the limits of normal conjunctival fornix anatomy in a healthy South Asian population. Ophthalmology. 2014;121:492–7. Williams GP, Saw VP, Saeed T, Evans ST, Cottrell P, Curnow SJ, et al. Validation of a fornix depth measurer: a putative tool for the assessment of progressive cicatrising conjunctivitis. Br J Ophthalmol. 2011;95:842–7. Brandt JD, DuBiner HB, Benza R, Sall KN, Walker GA, Semba CP, et al. Long-term safety and efficacy of a sustained-release bimatoprost ocular ring. Ophthalmology. 2017;124:1565–6. Trivedi RH, Wilson ME. A sustained-release intracanalicular dexamethasone insert (Dextenza) for pediatric cataract surgery. J AAPOS. 2021;25:43–5. Hosoya K, Lee VH, Kim KJ. Roles of the conjunctiva in ocular drug delivery: a review of conjunctival transport mechanisms and their regulation. Eur J Pharm Biopharm. 2005;60:227–40. Luchs JI, Nelinson DS, Macy JI, Group LACS. Efficacy of hydroxypropyl cellulose ophthalmic inserts (LACRISERT) in subsets of patients with dry eye syndrome: findings from a patient registry. Cornea. 2010;29:1417–27. Lee K, Lee G, Lee S, Park CY. Advances in ophthalmic drug delivery technology for postoperative management after cataract surgery. Expert Opin Drug Deliv. 2022;19:945–64. Dosmar E, Walsh J, Doyel M, Bussett K, Oladipupo A, Amer S, et al. Targeting ocular drug delivery: an examination of local anatomy and current approaches. Bioengineering. 2022;9:41. Bertens CJF, Dunker SL, Dias A, van den Biggelaar F, Nuijts R, Gijs M. Safety and comfort of an innovative drug delivery device in healthy subjects. Transl Vis Sci Technol. 2020;9:35. Jutley G, Carpenter D, Hau S, Booth D, Jasim HA, Tay E, et al. Upper and lower conjunctival fornix depth in healthy white caucasian eyes: a method of objective assessment. Eye. 2016;30:1351–8. Franceschiello B, Di Sopra L, Minier A, Ionta S, Zeugin D, Notter MP, et al. 3-Dimensional magnetic resonance imaging of the freely moving human eye. Prog Neurobiol. 2020;194:101885. Pflugfelder SC. Tear dysfunction and the cornea: LXVIII Edward Jackson Memorial Lecture. Am J Ophthalmol. 2011;152:900–9. e1. Jacobs L, Feldman M, Bender MB. Eye movements during sleep. I. The pattern in the normal human. Arch Neurol. 1971;25:151–9. Jacobs L, Feldman M, Bender MB. Eye movements during sleep. II. The pattern with upward gaze paralysis. Arch Neurol. 1971;25:212–7. Tauber J, Jabbur N, Foster CS. Improved detection of disease progression in ocular cicatricial pemphigoid. Cornea. 1992;11:446–51. Foster CS, Sainz De La Maza M. Ocular cicatricial pemphigoid review. Curr Opin Allergy Clin Immunol. 2004;4:435–9. Kheirkhah A, Blanco G, Casas V, Hayashida Y, Raju VK, Tseng SC. Surgical strategies for fornix reconstruction based on symblepharon severity. Am J Ophthalmol. 2008;146:266–75. Tan ST, Htoon HM, Davidson M, Rauz S, Mehta JS, Ong HS. Defining the limits of upper and lower conjunctival fornix depths in a healthy Asian Chinese population. Eye. 2025;39:2289–97. Bulut O, Kaplan A, Furundaoturan O, Kose T, Barut Selver O. Identification of normal fornix depth dataset generated with a validated fornix meter in healthy turkish population. Ocul Immunol Inflamm. 2024;32:713–7. Tang G, Ahmadi SA, Jillings S, Jeurissen B, Tomilovskaya E, Nosikova I, et al. MReye-Seg: development and validation of an automated MRI pipeline for standardised ocular and orbital morphometrics. Eye. 2025;39:3294–305. van Elst S, de Bloeme CM, Noteboom S, de Jong MC, Moll AC, Goricke S, et al. Automatic segmentation and quantification of the optic nerve on MRI using a 3D U-Net. J Med Imaging. 2023;10:034501. Yang JJ, Kim KH, Hong J, Yeon Y, Lee JY, Lee WJ, et al. Fully Automated segmentation of human eyeball using three-dimensional U-Net in T2 magnetic resonance imaging. Transl Vis Sci Technol. 2023;12:22. Kang E, Park JH, Yoo C, Kim YY. Elevated lamina cribrosa-sclera interface stress in glaucomatous eyes with optic disc haemorrhage. Br J Ophthalmol. 2026;110:410–6. Li Q, Zhan B, Liu T, Han Y, Xin S, Chen Z, et al. An automated optical coherence tomography to finite element analysis pipeline reveals key morphological determinants of optic nerve head biomechanics in glaucoma. Eye. 2026;40:238–44. Park J, Shin A, Demer JL. Finite element modeling of effects of tissue property variation on human optic nerve tethering during adduction. Sci Rep. 2022;12:18985. Jafari S, Lu Y, Park J, Demer JL. Finite element model of ocular adduction by active extraocular muscle contraction. Investig Ophthalmol Vis Sci. 2021;62:1. Munoz Sarmiento DM, Rodriguez Montano OL, Alarcon Castiblancoa JD, Cortes Rodriguez CJ. The impact of horizontal eye movements versus intraocular pressure on optic nerve head biomechanics: a tridimensional finite element analysis study. Heliyon. 2023;9:e13634. Basson N, Peng CS, Geoghegan P, van der Lecq T, Steven D, Williams S, et al. A computational fluid dynamics investigation of endothelial cell damage from glaucoma drainage devices. Sci Rep. 2024;14:3777. Panduro RMR, Monterrey C, Mantari JL, Canahuire R, Alvarez H, Miranda M, et al. Computational and experimental analysis of a Glaucoma flat drainage device. J Biomech. 2021;118:110234. Acknowledgements The authors thank the Institute for Basic Science (IBS) Center for Neuroscience Imaging Research (IBS-R015-D1) for providing MRI time and professional technical support. Funding This research was supported by the Digital Healthcare Research Grant through the Seokchun Caritas Foundation (SCY2503P). This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI22C071800). Author information Authors and Affiliations Contributions HMP and HSC were responsible for data analysis, manuscript writing and literature search. EC, JK, YY, HSC, JHK and WJL were responsible for data collection, literature review and study design. HWL and JJY were responsible for data collection, data extraction and MRI data analysis and processing. YJK was responsible for study design, supervision, data interpretation and manuscript writing. Corresponding authors Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary information Rights and permissions Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. About this article Cite this article Park, H.M., Cho, H.S., Cho, E. et al. Three-dimensional anatomy and dynamic changes of the conjunctival fornix assessed by high-resolution magnetic resonance imaging. Eye Open 2, 12 (2026). https://doi.org/10.1038/s44440-026-00018-8 Received: Revised: Accepted: Published: Version of record: DOI: https://doi.org/10.1038/s44440-026-00018-8