The distribution of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth in an adult population of Shahroud, Iran

Abstract

BackgroundOcular biometric parameters can be influenced by race, ethnicity, and genetics; their differences across different populations can probably explain differences in refractive errors in these populations. The aim of this study is to determine the normal range of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth in the population of Shahroud in the north of Iran.MethodsIn the first phase of Shahroud Eye Cohort Study, the 40–64 year old population were sampled cross-sectionally; 6311 were invited and 5190 (82.2%) participated in the study. Biometric examinations were done using the LENSTAR/BioGraph (WaveLight AG, Erlangen, Germany) after vision tests and before cycloplegic refraction tests. Any type of eye surgery, extensive pterygium, and lack of cooperation were used as exclusion criteria, and analyses were done with data from 4869 eyes.ResultsWe found a mean axial length of 23.14 mm (95% confidence interval [CI], 23.11-23.17), mean anterior chamber depth of 2.62 mm (95% CI, 2.60-2.63), mean lens thickness of 4.28 mm (95% CI, 4.27-4.29), and the mean vitreous chamber depth was 15.72 mm (95% CI, 15.70-15.75).Kolmogorov-Smirnov tests showed that the distribution of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth significantly differed from normal; axial length and vitreous chamber depth demonstrated a leptokurtic distribution as well.Axial length, anterior chamber depth, and vitreous chamber depth significantly decreased with age, and lens thickness significantly increased with age (p < 0.001). All indices were significantly higher in men.ConclusionsThe distributions of axial length, vitreous chamber depth, and lens thickness are reported for the first time in an Iranian adult population. Compared to other studies, axial length was in the mid range, nonetheless, studying axial length components showed that the Iranian population had smaller anterior chamber depth and lens thickness. Age and gender were significantly associated with all indices assessed in this study.

Lens Power in a Population-Based Cross-Sectional Sample of Adults Aged 40 to 64 Years in the Shahroud Eye Study

“…Consistent with this trend, the mean spherical equivalent was more than þ0.45 diopters higher in the older subjects, in both men and women (Table 3, two-way ANOVA for sex and age, P < 0.001). Significant changes in axial length and corneal power with age have been previously reported in this sample 29,30 ; but as can be seen in Table 3, despite the differences in the prevalence of emmetropia and hyperopia, the axial length/corneal radius ratio (AL/CR) did not differ with age (two-way ANOVA for sex and age, P < 0.476).…”

Corneal resistance factor and corneal hysteresis in a 6- to 18-year-old population

“…Similar studies give a detailed description of these indices in different populations. [13][14][15][16][17][18][19][20][21][22][23][24] Results in our study showed that the mean CRF was 11.74 mm Hg and its normal range was from 8.19 to 15.28 mm Hg. The mean CH in this study was 11.49 mm Hg with a normal range from 7.67 to 15.31 mm Hg.…”

“…Biometric indices, especially AL, play a role in the difference between sexes. From previous studies, 23,24 we know that girls have a smaller AL than boys. Also, findings in some studies 9,25 suggest an inverse association between biomechanical properties and AL.…”

The Relationship between Anterior Chamber Depth, Axial Length and Intraocular Lens Power among Candidates for Cataract Surgery

“…It has been proven that basic anatomical parameters (such as AL and ACD) in ophthalmology are variable in different countries according to ethnic groups, genetics and some environmental factors. In result, this may affect some parameters such as IOL power calculations, yet no study has specifically evaluated this matter (11, 12). Understanding region specific differences regarding IOL power calculations is vital for post cataract surgery evaluations.…”