Comparison of Corneal Layers and Anterior Sclera in Emmetropic and Myopic Eyes

Pekel, Gökhan; Yağcı, Ramazan; Acer, Semra; Ongun, Gülin Tuğba; Çetin, Ebru; Simavlı, Hüseyin

doi:10.1097/ico.0000000000000422

Cited by 35 publications

(37 citation statements)

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“…Among all the four meridians, the sclera was thinnest in the superior meridian in the current study, which is consistent with the results reported by the only in vivo study that investigated AST along vertical meridian in South Asians and Europeans. 20,26 Similar results were stated by Norman et al 26 after MRI of 11 enucleated eyes, where the thinnest sclera was found along the superior meridian and the thickest along the inferior meridian from the limbal to the equatorial area. However, the AST reported by Buckhurst et al 12 along each meridian is thicker than our findings, which could be attributed to the inclusion of episcleral tissue thickness for computing scleral thickness, because the poor axial resolution of AS-OCT used in their study (18 μm with AS-OCT vs. 8 μm with SS-OCT) makes it difficult to demarcate the boundary between the episclera and the sclera.…”

Section: Discussionsupporting

confidence: 76%

“…10,[14][15][16][17][18] Previous studies that reported peripheral AST have certain limitations in terms of the meridians investigated (temporal or nasotemporal meridians only) and included participants with -0.50 to -11.00 diopters (D) of myopic refractive errors. 19,20 In addition, there is limited information about the changes in scleral thickness that occur in various locations of sclera from anterior (limbus) to the posterior (foveal) region of the myopic eye.…”

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confidence: 99%

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Anterior Sclera Undergoes Thinning with Increasing Degree of Myopia

Dhakal

Vupparaboina

Verkicharla

2020

Invest. Ophthalmol. Vis. Sci.

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Citation: Dhakal R, Vupparaboina KK, Verkicharla PK. Anterior sclera undergoes thinning with increasing degree of myopia. Invest Ophthalmol Vis Sci. 2020;61(4):6. https://doi. org/10.1167/iovs.61.4.6 PURPOSE.Considering that ocular expansion is associated with scleral thinning, this study investigated variation in scleral thickness (anterior scleral thickness [AST] and posterior scleral thickness [PST]) in different meridians across emmetropes and a wide range of myopes. METHODS.A total of 95 participants (mean age, 24 ± 4 years) including emmetropes (spherical equivalent refractive error, ±0.75 diopters [D]; n = 20) and myopes (-1.00 to -27.25 D; n = 75) underwent ocular imaging with swept-source optical coherence tomography. All the images were analyzed using semiautomated custom-designed software to determine scleral thickness in 1-mm intervals. AST was estimated from limbus to 5 mm (n = 95), and PST from fovea to 5 mm (n = 25; high myopes only) along the horizontal and vertical meridian. RESULTS.The median spherical equivalent refractive error and axial length were −4.25 D (IQR, -12.50 to -1.00 D) and 25 mm (IQR, 23.72-28.35 mm), respectively. The anterior sclera was thinnest in the superior and thickest in the inferior region (475.3 ± 19.0 vs. 605.9 ± 18.6 μm; P < 0.001). The inferior AST alone decreased significantly with increasing magnitude of myopia (r = 0.27; P = 0.008). There were no differences in AST between nasal and temporal meridians (583.24 ± 15.00 vs. 587.09 ± 27.00 μm; P > 0.05). The mean subfoveal PST for the subset of high myopes was 251.7 ± 12.0 μm which was thinner than mean AST along all the meridians by more than 45%. The averaged scleral thickness peripheral to fovea (1-5 mm) was similar along different meridians (P > 0.05). CONCLUSIONS.The relative significant thinning of the anterior sclera along the inferior meridian with increasing degree of myopia compared with the other three meridians indicates the potential role of AST, especially in the inferior meridian, to act as a marker for myopia progression. E yes with myopia are more susceptible to develop patho-

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Section: Discussionsupporting

confidence: 76%

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confidence: 99%

Anterior Sclera Undergoes Thinning with Increasing Degree of Myopia

Dhakal

Vupparaboina

Verkicharla

2020

Invest. Ophthalmol. Vis. Sci.

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“…(458 μm) in their populations of normal adults. Of note, Pekel et al . also examined the temporal scleral thickness in normal adults, and reported substantially higher thickness values compared to our results and to those of Ebneter et al .…”

Section: Discussionsupporting

confidence: 71%

“…A small number of recent studies have reported upon anterior scleral thickness using AS‐OCT in normal adults with a variety of ages . Ebneter et al .…”

Section: Discussionmentioning

confidence: 99%

“…A number of recent studies have used AS‐OCT to examine the in vivo changes in anterior scleral morphology associated with the presence of glaucoma, glaucoma filtration surgery, ocular therapeutic procedures, keratoconus, contact lens wear and the presence of inflammatory conditions such as scleritis and episcleritis . A small number of studies have also reported upon the thickness characteristics of the anterior sclera in normal adult eyes, and others have examined the normal dimensions of the bulbar conjunctiva using AS‐OCT …”

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confidence: 99%

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Diurnal variation of anterior scleral and conjunctival thickness

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Alonso‐Caneiro

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et al. 2016

Ophthalmic Physiologic Optic

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This study provides the first evidence of diurnal variations occurring in the thickness of the anterior sclera and conjunctiva. Studies requiring precise measures of these anatomical layers should therefore take time of day into consideration. The majority of the observed changes occurred in the early morning immediately after waking and were of larger magnitude in the conjunctiva compared to the sclera. Thickness changes at other times of the day were of smaller magnitude and generally not statistically significant.

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Understanding Myopia: Pathogenesis and Mechanisms

2019

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• Visual environment (or the quality of the retinal image) modulates the refractive development of the eye. • Ocular response to form-deprivation and lens induced defocus is evident across a wide range of animal species, including humans. • The visual system appears to be more sensitive to myopic than hyperopic defocus. • Evidence suggests that greater time spent outdoors is protective against development and progression of myopia in children.

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Comparison of Corneal Layers and Anterior Sclera in Emmetropic and Myopic Eyes

Abstract: The thickness of anterior wall structures and preocular tear film of patients with moderate to high myopia are not statistically different compared with those of healthy controls.

Cited by 35 publications

References 28 publications

Anterior Sclera Undergoes Thinning with Increasing Degree of Myopia

Anterior Sclera Undergoes Thinning with Increasing Degree of Myopia

Diurnal variation of anterior scleral and conjunctival thickness

Understanding Myopia: Pathogenesis and Mechanisms

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