In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

Le, Qihua; Cordova, Daniel; Xu, Jianjiang; Deng, Sophie X.

doi:10.1167/tvst.7.4.12

Cited by 14 publications

(5 citation statements)

References 17 publications

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“…Figure 5 b shows the B-mode image of the OCE field-of-view where estimations of Lamb wave speed were conducted and corresponds to the dashed box in Figure 5 a. Here, the limbus region was selected based on previous reports using OCT imaging and histology 40 and giving extra tolerance in the segmentation as follows: (1) we define a starting point as the intersection of the projective line following the iris with any visible posterior surface in the eye's anterior segment, as shown in Figure 5 a; then (2) from that point we trace a line perpendicular and toward the surface of the eye's anterior segment; finally, (3) we roughly delimit the lateral boundaries of limbus by tracing parallel segments separated 1 mm to the left and right side of the line calculated in (2).…”

Section: Resultsmentioning

confidence: 99%

Dynamic Optical Coherence Elastography of the Anterior Eye: Understanding the Biomechanics of the Limbus

Zvietcovich

Nair

Singh

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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Purpose Currently, the biomechanical properties of the corneo-scleral limbus when the eye-globe deforms are largely unknown. The purpose of this study is to evaluate changes in elasticity of the cornea, sclera, and limbus when subjected to different intraocular pressures (IOP) using wave-based optical coherence elastography (OCE). Special attention was given to the elasticity changes of the limbal region with respect to the elasticity variations in the neighboring corneal and scleral regions. Methods Continuous harmonic elastic waves (800 Hz) were mechanically induced in the sclera near the corneo-sclera limbus of in situ porcine eye-globes ( n = 8). Wave propagation was imaged using a phase-sensitive optical coherence tomography system (PhS-OCT). The eyes were subjected to five different IOP-levels (10, 15, 20, 30, and 40 mm Hg), and spatially distributed propagation velocities were calculated along corneal, limbal, and scleral regions. Finite element analysis (FEA) of the same regions under the same excitation conditions were conducted for further validation of results. Results FEA demonstrated that the stiffness of the heterogeneous cornea-limbus-sclera transition can be characterized by phase velocity measurements of the elastic waves produced at 800 Hz in the anterior eye. Experimental results revealed that the wave speed in the limbus ( c L = 6.5 m/s) is between the cornea ( c c = 2.9 m/s) and sclera ( c s = 10.0 m/s) at a physiological IOP level (15 mm Hg) and rapidly increases as the IOP level is increased, even surpassing the wave speed in the sclera. Finally, the change in elastic wave speed in the limbus (Δ c L ∼18.5 m/s) was greater than in the cornea (Δ c c ∼12.6 m/s) and sclera (Δ c s ∼8.1 m/s) for the same change in IOP. Conclusions We demonstrated that wave-based OCE can be utilized to assess limbus biomechanical properties. Moreover, experimental evidence showed that the corneo-scleral limbus is highly nonlinear compared to the cornea and sclera when the eye-globe is deformed by an increase of IOP. This may suggest that the limbus has enough structural flexibility to stabilize anterior eye shape during IOP changes.

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Section: Resultsmentioning

confidence: 99%

Dynamic Optical Coherence Elastography of the Anterior Eye: Understanding the Biomechanics of the Limbus

Zvietcovich

Nair

Singh

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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“…OCT provides a more rapid and accurate means to explore the structure of the corneal limbus under pathological conditions than ex vivo histologic studies because it allows for the omission of the fixation and dehydration process [ 13 ]. In the current study, we evaluated the status of the corneal limbus of patients with pterygium via OCT and further explored potential effects of age.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

Wang

et al. 2022

JCM

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Previous studies suggest that regions of corneal limbus may possess structural differences. We aimed to investigate the limbal changes associated with pterygium and aging via optical coherence tomography (OCT). Palisades of Vogt epithelial thickness (POV-ET) and Bowman’s membrane epithelial thickness (BM-ET) were measured at the nasal, temporal, superior, and inferior quadrants of patients with pterygium and healthy subjects of different ages. Values were expressed as a ratio that functioned as an index used to evaluate the change of limbus. Ratio values determined for quadrants of the corneal limbus were correlated highly in young healthy subjects. Further, parameter values were significantly greater than those of elder healthy subjects. In young subjects, the temporal and superior quadrants of patients with pterygium were significantly lower than those of healthy subjects. Temporal and superior quadrants of elder pterygium patients affected by both pterygium and age were significantly lower than those of healthy subjects; however, the inferior quadrant of elderly pterygium patients was significantly higher than that of age-matched healthy subjects. Our findings revealed that the thickness of limbal epithelium was negatively correlated with age, while pterygium led to the thinning of the temporal and superior limbal epithelium and inferior limbal epithelial thickening.

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“…12 To date, there is no clear delineation of anatomical limbus based on AS-OCT; however, it is grossly visualized as the transition of hyporeflectivity and hyperreflectivity using scleral spur as anatomical landmark. Le et al 26 attempted to define limbus on AS-OCT by measuring difference between scleral spur and Bowman layer. Future imaging studies would be needed to accurately determine limbal clearance on AS-OCT with enhanced visualization of scleral spur.…”

Section: Limbusmentioning

confidence: 99%

Novel High-Resolution Imaging Using ANTERION Optical Coherence Tomography to Assess Fluid Reservoir Change in Scleral Lens Periphery

Tran¹,

Roberts²,

Mahmoud³

et al. 2022

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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Objectives:To assess scleral lens fluid reservoir (FR) change simultaneously in four quadrants with single acquisition using novel ANTERION anterior segment swept-source optical coherence tomography (SS-OCT).Methods:A prospective, observational, clinical study of 18 subjects (30 eyes) was performed on adults fitted with a scleral lens for ocular surface disease (n=8), irregular cornea/scar (n=7), and corneal ectasia (n=15). ANTERION anterior segment SS-OCT imaging was obtained at the initial visit and at the follow-up to determine pre and post scleral lens settling, measured in microns, centrally and peripherally. Peripheral measurements were grouped into four quadrants. Repeated-measures ANOVA was performed comparing vault post minus pre differences by quadrant, and TTests comparing difference in FR by lens design were performed with a significant threshold at P<0.05.Results:The mean central scleral lens settling was significant at −48.3±41.7 μm. The change in FR by quadrant was superior (S): −47.8±67.3 μm, inferior (I): −68.0±102.2 μm, nasal (N) −46.3±63.4 μm, and temporal (T): −56.7±49.3 μm. There were no significant differences in lens settling between the quadrants. Within the three categories, the irregular cornea group experienced significantly greater lens settling. There was no significant difference in central FR when comparing lens design or lens diameter.Conclusions:The ANTERION SS-OCT allows for high-resolution central and peripheral assessment of FR in scleral lens wear. With increased technology available for scleral lens customization, this imaging modality can assist in more detailed assessment in quadrant-specific scleral lens designs.

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In Vivo Evaluation of the Limbus Using Anterior Segment Optical Coherence Tomography

Cited by 14 publications

References 17 publications

Dynamic Optical Coherence Elastography of the Anterior Eye: Understanding the Biomechanics of the Limbus

Dynamic Optical Coherence Elastography of the Anterior Eye: Understanding the Biomechanics of the Limbus

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

Novel High-Resolution Imaging Using ANTERION Optical Coherence Tomography to Assess Fluid Reservoir Change in Scleral Lens Periphery

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