The study covers a sample of 3,334 people residing in Colombian in the departments of Atlántico, Caldas, Casanare, Cauca, Cesar, Nariño, Quindío, Santander and Tolima, and it shows that there is a statistically significant influence of variables such as gender, area of residence (rural / urban), refractive condition, anterior chamber depth and corneal curvature over axial length of the eyeball.
The data show particularly that the mean axial length of the studied population is 23.13mm, similar to that reported for the Iranian population (mean axial length 23.14 mm),24 but lower than the results of studies carried out in Port Harcourt in the state of Rivers, Nigeria (mean axial length 23.2mm),25 China (23.25 mm)26 (23.32 mm),27 India (23.28 mm),28 Nigeria (23.31 mm),29 Saudi (mean AL 23.48 mm),30 in a Mexican population (mean AL 23.44 mm)3 and in the systematic review carried out by de Hoffer et al (23.43 mm).31 It is higher, however, than that reported in Gujrat India (22.78 mm)32 and the Sudan (23.09 mm)33; even so, were carried out in population groups with different sample sizes and ages.
Additionally, when analyzing the relationship of axial length and sex, it was evidenced that men have a higher axial length than women (23.29 mm VS 22.92 mm). A similar finding is reported in studies carried out in the Mexican population,3 in a suburban Caucasian population residing in Australia aged 49 years or older (23.76 mm Vs 23.19 mm),34 in Saudi Arabia (23.61 mm Vs 23.34 mm),30 and in Nigeria, the latter showing a mean difference of .70 ± .10 mm (P≤.01).25 In the study by Hoffer and Savini that included different races, a higher AL for all races was also evidenced in men than in women (Westerners 23.77 mm Vs 23.23 mm, Latinos 23.80mm vs 23.33mm, Asian 24.00mm vs 23.33mm, Middle East 23.42mm vs 22.99mm, and Asian Indian 23.68mm vs 23.23).31 This result is consistent with the hypothesis tested by various studies in which a relationship exists between the dimensions of the eyeball and anthropometric measurements.2
In Port Harcourt, Nigeria, the relationship between age and axial length was studied without considering the refractive condition. There was shown to be no statistically significant difference. A longer axial length was recorded in men aged 51 to 60 and in women between 41 and 50 after which a decrease in axial lengths was observed in both sexes.25 In Saudi Arabia, a shorter axial length was found in people over 40 years of age (23.35 mm vs. 24.23).30 In the present study, the refractive condition was considered, and it was evidenced that myopic women aged between 21 and 40 have a higher axial length (28.45mm) than myopic men (26.03mm) of the same age group.
In this regard, in a study with 152 participants carried out between 2010 and 2011 in West Bengal, India between 8 and 70 years, an average axial length for emmetropes of 23.26 mm (± .64)34 is reported. This result coincides with the data in the group of women from 11 to 20 years of age 23.23 (± .05). In the case of myopic patients, an average of 25.31 mm (± 1.12) was recorded, which is close to results in the group from 21 to 40 years of age 26.03 mm (± 1.48). In hyperopes, the average axial length was 22.50 (± 1.38), close to that registered in women between 21 and 40 years of age observed in the present study 22.94 (± .10).
Additionally, the anterior chamber depth was 3.32mm higher than that reported in the studies of West Bengal,34 India (2.97mm),28 Saudi Arabia (3.10 mm),30 Nigeria (3.23mm),35 and that reported in the review by Hoffer and Savini (3.09mm).31 In the study carried out in a Nigerian population, it was also found that men tend to have a deeper anterior chamber than women,35 a finding that agrees with the results of the present study, since an anterior chamber depth of 3.43mm was found in men and of 3.25mm in women.
About keratometry, the average of the flattest K was 43.08 diopters, a flatter value than in the Saudi population 43.74 diopters 30 and in the study by Hoffer and Savini 44.01 diopters.31
On the other hand, with the participants of this research, the prevalence of astigmatism and hyperopia was 35.60% and 35.09%, higher than in Mashhad, Iran since the prevalence of these two refractive errors in individuals>15 years of age was 25.64% and 34.21%, 36 while the proportion of myopia was 3.64% in individuals ≤ 15 years of age, and for subjects> 15 years old, it was 22.36%. In the present study the frequency of myopia was 4.56%.
Finally, considering advantages of this research, the inclusion of an urban and rural population residing in a Latin American country should be emphasized. Also, to be highlighted is the fact that it involves a wide age range that include children, adolescents and young adults, age groups that do not normally correspond to a population commonly addressed in studies on ocular biometric parameters. As limitations we recognize, the variations in the physical conditions for the performance of the exams, and the failure to include information related to the level of education15 and anthropometric measurements.