Eur J Anat, 5 (3): 145-150 (2001)

Consolidating the anatomical relationship between ocular axial length and spherical equivalent refraction

Cegarra M.J., Casanova Izquierdo J., Alonso L., Hernandez Gil de Tejada T., Rahhal M.S., Martinez Soriano F., Sanchis Gimeno J.A.

Dpto. de Ciencias Morfologicas, Facultad de Medicina, Av/Blasco Ibáñez, 17, E-46010 Valencia, Spain

ABSTRACT The basis of refractive error is ocular axial length since this will indicate the presence of either a myopic eye or a hyperopic one, Today, ultrasonic biometry can be used to study the anatomical differences between the ocular myopic and the hyperopic globe. Following on from this, we analysed the anatomical relationship between ocular axial length, refraction and the degree of refractive error. To this end, we measured the ocular axial length with the Compuscan A-B Storz ultrasonic biometer (San Louis, MO, USA) in 100 patients with myopia (n=100; mean age 33.53±8.15; 51.0% women and 49.0% men) and 100 with hyperopia (n=100; mean age 30.90±7.73; 56.0% women and 44.0% men). We established three groups of myopic patients (group M1: -6.50 to -12.00 diopters; group M2: -12.50 to -18.00 diopters; group M3: -18.25 to -24.00 diopters) and two groups of hyperopic patients (group H1: +1.75 to +4.00 diopters; group H2: +4.50 to +9.50 diopters). Mean ocular axial length was 27.11±1.55 mm in M1, 28.70±1.55 in M2, 29.78±1.10 in M3, 21.66±0.83 in H1 and 21.31±0.92 in H2 (p < 0.001). Among the myopic groups (p < 0.001) and between the hyperopic groups (p=0.025), differences in mean ocular axial length were significant. Women had an ocular axial length, which was significantly less in the hyperopic groups and in M1 (p=0.020 in H1, p=0.046 in H2 and p=0.027 in M1). In M2 and M3, no significant differences were found (p=0.742 and p=0.104, respectively). Our study confirms the involvement of ocular axial length in the refractive state and reveals a major difference in the way mean ocular axial length behaves between the sexes as a function of the degree of myopic error presented.

Keywords: adult, anatomy, article, biometry, device, female, human, hypermetropia, major clinical study, male, myopia, refraction error