Anterior Sclera Undergoes Thinning with Increasing Degree of Myopia

Abstract

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-

Shape analysis of rectus extraocular muscles with age and axial length using anterior segment optical coherence tomography

“…The distance between the cornea and the insertion site of the rectus EOM was similar to that reported previously ( Table 4 ) [ 16 – 23 ]. However, Indians have a longer average of 8.7 mm of LR and 7.3 mm of MR in the direct measurements [ 19 ].…”

Relationship between Axial Length and Corneo-Scleral Topography: A Preliminary Study

“…There were no significant correlations between central corneal stromal thickness and anterior scleral thickness in myopic participants. These results contrast with the recent study from Rohit Dhakal et al that suggested that the use of the anterior scleral thickness might be a biomarker for myopia progression [ 7 ]. In their study, Rohit Dhakal at al.…”

Anterior Scleral Thickness in Myopic Eyes and Its Association with Ocular Parameters

“…Previous histomorphometric studies have demonstrated that anterior scleral thickness measured at the limbus and ora serrata was not significantly different in nonaxially elongated eyes and axially elongated eyes [5]. Buckhurst et al [14] and Pekel et al [15] also reported similar findings that axial length was not associated with the anterior scleral thickness using in vivo measurements of the sclera using optical coherence tomography (OCT), whereas more recently, Dhakal et al [16] demonstrated significant thinning of the anterior sclera along the inferior meridian with increasing axial length.…”

“…However, little attention has been given to the anterior sclera, and there is limited information in this regard. Although several studies have investigated the anterior sclera in myopic eyes, the results are conflicting [5, 14-16]. Previous histomorphometric studies have demonstrated that anterior scleral thickness measured at the limbus and ora serrata was not significantly different in nonaxially elongated eyes and axially elongated eyes [5].…”