Abstract
Variations in ocular sizes exist in the population and this may be congenital or pathological. Reference values are therefore essential in management of ophthalmic pathologies in the fields of Ophthalmology and Neurology. The aim of the study was to establish computer tomography (CT) scan reference values of ocular sizes in Makurdi, north central Nigeria. To avoid unjustifiable radiation dose, data obtained for this study was on 111 patients referred on account of other medical conditions, to the Radiology department for CT brain scan using Philip Brilliance 16. Measurements were taken at mid-ocular axial slices with maximum anterior-posterior and transverse dimensions. The mean ± 2 SD) ocular sizes in anterior-posterior(AP) and transverse diameter(TD) for both eyes were 22.1mm ± 1.88mm and 22.9mm ± 1.20mm respectively. The right eye was 21.9mm ± 2.33mm and 22.9mm ± 1.09mm and the left eye was 22.3mm ± 1.24mm and 23.0 ± 1.30 mm in both AP and TD respectively. The measurements were slightly higher on the left. The mean ocular measurements were higher in males and were statistically significant in the transverse measurements on both sides (P<0.04). Adult eye size was attained at age group 11-20 years and subsequently at age >70 years, there was slight reduction in ocular dimensions. Established ocular sizes on CT therefore showed that males had slightly larger eyeballs in comparison to females and there was some reduction of ocular sizes with age.
Highlights
The human eye has well established spaces.Congenital and acquired variations in the depth of these spaces determine the sizes of the eyeball which may affect management of cases in the fields of Ophthalmology and Ophthalmoneurology
The ocular dimensions were obtained in anterior-posterior (AP) diameter or axial length and transverse diameter (TD) or width of the eyeball
Saalam et al[5] showed that the AP dimensions in a study on ocular biometrics were higher than the TD lengths and the right eyeball was slightly smaller than the left one, no concrete reasons could be adduced for these differences
Summary
Congenital and acquired variations in the depth of these spaces determine the sizes of the eyeball which may affect management of cases in the fields of Ophthalmology and Ophthalmoneurology. In ophthalmology; congenital glaucoma, eyeball trauma, cancer, retinoblastoma, macrophthalmia, microphthalmia, hypermetropia, myopia, astigmatism and presbyopia are all associated with changes in the size of the eyeball.[2 ,3]. In Neurology, current interest in optic nerve sheath diameter (ONSD) and its possible connection with the intracranial pressure monitoring requires precise transverse size ocular measurements. The knowledge of normative size of the eyeball is as important as measurement of the normative ONSD.[4] Ocular normogram will aid in diagnosis of raised intraocular pressure.[5] Newer Computed Tomography (CT) scans have greatly enhanced oculometric research and made it
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