Quantification of Retinal Nerve Fiber Layer Thickness in Highly Myopic Eyes Using Optical Coherence Tomography

以光學同調斷層掃描來評估高度近視眼之視盤周圍視網膜神經纖維層厚度

許祺鑫(Chi-Hsin Hsu) ； 施永豐(Yung-Feng Shih)

《中華民國眼科醫學會雜誌》 49卷2期 (2010/06) Pp. 162-173

https://doi.org/10.30048/ACTASOS.201006.0007

摘要

目的：評估視盤周圍視網膜神經纖維層厚度（以光學同調斷奮掃描）與眼軸長倔光度數的關係性。
方法：這個回溯研究包括了38個眼睛。樣本皆為近視眼，皆以超音波測量過眼軸長及以光學同調斷層掃描儀測量視盤周圍視網膜神經纖維層厚度。樣本中若有其他已知眼科疾病則被排除在研究之外。以眼軸長，總共分成租來討論：第一組：小於26 mm；第二組：26到27 mm；第三組：大於27 mm。各組之間，分別以平均厚度及不同區的厚度來比較。視網膜神經纖維層厚度與眼軸長和屆光度數的關係則以線性迴歸的方式來評估。根據高度近視的定義，丙以眼軸長為26.5 mm為分界，比較上下耐且間神番殲維層厚度的差別。
結果：以視網膜神經纖維層平均厚度來看，分別為：第一組：106.06+/-11.86μm；第二組：104.81+/-11.60μm；第三組：92.81+/-14.19μm；各組間呈現明顯的差異（P=0.018）。以線性迴歸來看，隨著眼軸長的增加，神經纖維層厚度明顯減少(r=-0.499, p=0.001)：屈光度數負值的增加，亦有同樣的趨勢(r=0.125, p=0.455)。以平均厚度來看，若以眼軸長26 mm為界，上下兩組間沒有明顯差異；若以27 mm為界，則呈現顯著差異：26.5 mm則是一個剛好有意義的臨界值(p=0.025)。
結論：隨著近視的增加，視網膜神經纖維層厚度會減少。所以，當我們評估青光眼時，必須考慮到近視程度對視網膜神經纖維層厚度的影響。然而，在考慮到以光學同調斷層掃描所測得的視網膜神經纖維層厚度之影響時，眼軸長度是較好的參考指標。在神經纖維層厚度減少的程度上，眼軸長26.5 mm為有意義的臨界值。

並列摘要

Purpose: To evaluate the relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and the axial length/refractive error of the eye.
Methods: Thirty-eight myopic eyes from 38 patients were studied retrospectively. Axial length was measured using A-scan ultrasonography and RNFL was measured using OCT. Subjects with identified ocular diseases were excluded. Patients were divided into three groups by axial length measurements. Group I: ＜26 mm, Group Ⅱ 26–27 mm, and Group Ⅲ: ＞27 mm. Average and segmental RNFL thicknesses were compared among the groups. Associations between RNFL measurements and axial length and spherical equivalents were evaluated using linear regression analysis. Taking into consideration the definition of high myopia, RNFL thickness and axial length＜or＞26.5 mm were also compared.
Results: The average RNFL thickness for each of the three groups was 106.06±11.86 μm for Group Ⅰ, 104.81±11.60 μm for Group Ⅱ, and 92.81±14.19 μm for Group Ⅲ (p=0.018). The average RNFL thickness decreased with increasing axial length (r=-0.499, p=0.001) and negative refractive power (r=0.125, p=0.455). There was no statistically significant difference between axial lengths of greater than 26 mm and less than 26 mm. However, when the axial length was set to 27 mm, results showed a major distinction. The axial length of 26.5 mm was a meaningful threshold for differentiation (p= 0.025).
Conclusions: As the level of myopia increased, the thickness of the RNFL decreased. Therefore, analysis of RNFL thickness in the evaluation of glaucoma should always be interpreted with reference to the refractive status. Axial length is a better reference when analyzing RNFL thickness measured by OCT. The axial length of 26.5 mm was a meaningful threshold that suggested decreasing RNFL thickness.

並列關鍵字

Retinal nerve fiber layer thickness ； optical coherence tomography ； axial length ； refractive error ； glaucoma