Hashemi Hassan, Khabazkhoob Mehdi, Miraftab Mohammad, Emamian Mohammad Hassan, Shariati Mohammad, Abdolahi-Nia Tahereh, Fotouhi Akbar
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran ; Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
J Ophthalmic Vis Res. 2013 Jul;8(3):220-6.
To determine the distribution of axial length (AL) to corneal radius of curvature (CRC) ratio and to evaluate its association with refractive errors in an Iranian population.
In this cross sectional study, multistage cluster sampling was used to select subjects 40-64 years of age residing in Shahroud, northern Iran. All subjects underwent manifest and cycloplegic refraction, and biometry using the Allegro Biograph (WaveLight AG, Erlangen, Germany). Individuals with a history of intraocular surgery, extensive pterygia and ocular trauma were excluded.
Of a total of 6,311 patients, 5190 (82.2%) participated in the study. We excluded 247 patients to adhere with study criteria and 132 patients due to missing data. Mean AL/CRC was 3.034 [95% confidence interval (CI), 3.031-3.037]. AL/CRC was 3.028 and 3.042 in female and male subjects, respectively (P<0.001). The R2 coefficients between spherical equivalent (SE) refractive error and AL/CRC, AL, CRC, lens thickness, and anterior chamber depth were 0.607, 0.351, 0.012, 0.038, and 0.091, respectively. Linear regression showed a 12.1 diopter (D) shift towards myopia with every 1 unit increase in AL/CRC (P<0.001). Mean AL/CRC was 3.472 among myopes with SE less than-5.0D; this value decreased linearly and was as low as 2.690 among hyperopes with SE more than 5.0D. R2 coefficients for AL/CRC with spherical and cylindrical power were 0.560 and 0.071, respectively.
Minimal changes in AL/CRC lead to large changes in refractive error. The correlation between refractive errors was significantly stronger with the AL/CRC ratio than with AL and CRC alone.
确定眼轴长度（AL）与角膜曲率半径（CRC）比值的分布情况，并评估其与伊朗人群屈光不正的相关性。
在这项横断面研究中，采用多阶段整群抽样法选取居住在伊朗北部沙赫鲁德的40 - 64岁受试者。所有受试者均接受了显验光和睫状肌麻痹验光，并使用Allegro Biograph（德国爱尔朗根WaveLight AG公司）进行生物测量。排除有眼内手术史、广泛翼状胬肉和眼外伤史的个体。
在总共6311例患者中，5190例（82.2%）参与了研究。为符合研究标准，我们排除了247例患者，因数据缺失又排除了132例患者。平均AL/CRC为3.034[95%置信区间（CI），3.031 - 3.037]。女性和男性受试者的AL/CRC分别为3.028和3.042（P<0.001）。球镜等效（SE）屈光不正与AL/CRC、AL、CRC、晶状体厚度和前房深度之间的R2系数分别为0.607、0.351、0.012、0.038和0.091。线性回归显示，AL/CRC每增加1个单位，近视度数向近视方向偏移12.1屈光度（D）（P<0.001）。SE小于 - 5.0D的近视患者平均AL/CRC为3.472；该值呈线性下降，在SE大于5.0D的远视患者中低至2.690。AL/CRC与球镜度数和柱镜度数的R2系数分别为0.560和0.071。
AL/CRC的微小变化会导致屈光不正的较大变化。屈光不正与AL/CRC比值之间的相关性明显强于单独与AL和CRC的相关性。
