Journal of Korean Ophthalmic Optics Society (한국안광학회지)

The Korean Ophthalmic Optics Society (한국안광학회)
권호 표지

Comparison of Corneal Asphericity with Measuring Range

측정 범위에 따른 각막비구면계수의 비교

  • Received : 2012.11.05
  • Accepted : 2012.12.15
  • Published : 2012.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

Purpose: The purpose of this study is to investigate the changes of asphericity according to diameter and direction of the cornea. Methods: The changes of asphericity according to diameter and direction of cornea is measured by using Pentacam(Oculus Co., Germany), as targeting 57 adults (average $27.0{\pm}4.8$, 20 men, 37 women) without any ophthalmic diseases, which may be effective in eyesight, and refractive surgery. Results: As diameter increases in every direction based on the corneal vertex, asphericity has attentively increased (p<0.05), and the size of asphericity in each direction from every measured diameter showed as superior > nasal > inferior > temporal. In group comparison by nearsightness and astigmatism level, asphericity measured high when nearsightness and astigmatism levels were higher, and this appears to be statistically attentive.(p<0.05). Conclusions: Asphericity of cornea significantly increased according to increase of diameter of cornea, and as measured figure or increased quantity appeared differently in all directions based on corneal vertex, so it helps to understand shape of cornea, and considered that is the part to be considered during manufacturing and fitting of RGP lenses.

목적: 본 연구의 목적은 각막의 직경과 방향에 따른 비구면계수 변화를 알아보고자 하였다. 방법: 시력에 영향을 줄 수 있는 안과적 질환이 없고 굴절교정 수술 경험이 없는 성인 57명(평균 $27.0{\pm}4.8$세, 남 20명, 여37명)을 대상으로 각막비구면계측기(Pentacam, Oculus Co., Germany)을 이용하여 각막의 직경과 방향에 따른 비구면계수 변화를 측정하였다. 결과: 각막정점을 기준으로 모든 방향에서 직경이 증가함에 따라 비구면계수가 통계적으로 유의하게 증가하였으며(p<0.05), 측정된 모든 직경에서 방향별 비구면계수의 크기는 상측> 비측> 하측> 이측 순으로 나타났다. 강주경선과 약주경선에 따른 비구면계수와 변화량은 강주경선에서 높게 측정되었으며 이는 통계적으로 유의한 것으로 나타났다(p<0.05). 결론: 각막의 비구면계수는 각막의 직경이 증가함에 따라 유의하게 증가하였고, 각막정점을 기준으로 모든 방향에서 측정된 수치나 증가량이 다르게 나타나므로 각막형상을 이해하는데 도움이 되고 RGP 렌즈 제조와 피팅시 고려되어야 할 부분이라 생각된다.

Keywords

References

  1. Gonzalez-Meijome JM, Villa-Collar C, Montes-Mico R, Gomes A. Asphericity of the anterior human cornea with different corneal diameters. J Cataract Refract Surg. 2007;33(3):465-473. https://doi.org/10.1016/j.jcrs.2006.11.004
  2. Lotmar W. Theoretical eye model with aspherics. J Opt Soc Am. 1971;61(11):1522-1529. https://doi.org/10.1364/JOSA.61.001522
  3. Davis WR, Raasch TW, Mitchell GL, et al. Corneal asphericity and apical curvature in children: a cross-sectional and longitudinal evaluation. Invest Ophthalmol Vis Sci. 2005;46(6):1899-1906. https://doi.org/10.1167/iovs.04-0558
  4. Holmes-Higgin DK, Baker PC, Burris TE, Silvestrini TA. Characterization of the aspheric corneal surface with intrastromal corneal ring segments. J Refract Surg. 1999; 15(5):520-528.
  5. Kiely PM, Smith G, Carney LG. The mean shape of the human cornea. Optica Acta. 1982;29(8):1027-1040. https://doi.org/10.1080/713820960
  6. Lee SJ, Park SJ, Chun YY. The Change in corneal Eccentricity on the correction of Refraction Error Using Reverse Geometry Lens. J Korean Oph Opt Soc. 2010;15(2):145- 150.
  7. Liou HL, Brennan NA. Anatomically accurate, finite model eye for optical modeling. J Opt Soc Am A. 1997;14(8):1684- 95. https://doi.org/10.1364/JOSAA.14.001684
  8. Horner DG, Soni PS, Vyas N, Himebaugh NL. Longitudinal changes in corneal asphericity in myopia. Optom Vis Sci. 2000;77(4):198-203. https://doi.org/10.1097/00006324-200004000-00012
  9. Yang SW, Lee NY, Kim SY. The effect of cycloplegia on vision and stereopsis: Comparison between before and after cycloplegia. J Korean Ophth Soc. 2006;47(9):1454- 1458
  10. Kim HJ, Lee DH. Corneal asphericity of myopia in Korean. J Korean Oph Opt Soc. 2006;11(2):109-114.
  11. Anera RG, Jimenez JR, Jimenez del Barco L, Diaz JA. Corneal asphericity on visual function after refractive surgery. Optik-International Journal for Light and Electron Optics. 2002;113(2):83-88. https://doi.org/10.1078/0030-4026-00124
  12. Lam AK, Douthwaite WA. Application of a modified keratometer in the study of corneal topography on Chinese subjects. Ophthalmic Physiol Opt. 1996;16(2):130- 134. https://doi.org/10.1016/0275-5408(95)00015-1
  13. Townsley MG. New knowledge of the corneal contour. Contacto. 1970; 13(3):38-43.
  14. Eghbali F, Yeung KK, Maloney RK. Topographic determination of corneal asphericity and its lack of effect on the refractive outcome of radial keratotomy. Am J Ophthalmol. 1995;119(3):275-280.
  15. Kim SY, Choi JH, Park YH, Chang BS, Mah KC, Lee YC. Analysis of refractive error and corneal asphericity in elementary school students in Ilsan city. J Korean Oph Opt Soc. 2008;49(8):1317-1322. https://doi.org/10.3341/jkos.2008.49.8.1317
  16. Lee HJ, Jung SJ, Baek SS, Jung MA, Kim HJ. Correlation of central and peripheral corneal thickness by ages. Korean J Vis Sci. 2009;11(2):127-135.