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Aim: This study was aimed to assess the range of optic nerve, optic nerve sheath diameter and optical axial length and to find if there is any relation between them considering the refractive state of the eye to be as a data base in Sudanese adult students. Materials and Methods: This is a cross-sectional prospective study conducted at the University Eye Hospital, Photography Department, Gabra, Khartoum. The study included 250 healthy Sudanese adult students (500 eyes) of AL-Neelain University Faculty of Optometry and Visual Science 6.6% was hypermetrope, 24.6% myope and 68.8% emmetrope on a period of five months from May to September 2017. Permition was taken from consultant committee of the University Eye Hospital and Ophthalmic Photography Department managers, verbal consent was taken from the volunteers. Demographic data was taken. Vision was measured by Snellens E chart (ELLIS OPTICAL Co Ltd UK). Objectives refraction was done with Auto Kerato-Refractometer (TOPCON, KR-8900, POWER 75 VA, Japan). Outer eye was examind with YZ5G slit lamp (POWER 58 VA, 12V 30W halogen bulb). Inner eye with NIDEK NM-1000 Fundus Camera. Optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) 3mm behind the globe both with optical axial length (OAL) measured by 6000 A/B Scan ophthalmic ultrasound. All measurements were taken twice and the average was recorded. Results: The mean age of the studied population was 20.6±2.06 years. Males were 34(13.6%) and females were 216(86.4%). Their vision was ranged from 0.016 to 1.2 with mean of 0.94±0.24±SD. The optical axial length ranged from 21 to 30mm with mean of 26.44±1.34 mm for emmetropics, 27.35 ±1.30mm for myopics and 26.34 ±1.05mm for hypermetropics. Range of optic nerve diameter was from 2.81mm to 4.18mm with mean of 3.16±0.16mm for emmetroics, 3.17±0.19mm for myopics, and 3.26±0.22mm for hypermetropics. Optic nerve sheath diameter was ranged from 3.98 to 6.53 with mean of 4.61±0.31mm for emmetropics, 4.58±0.30 for myopics and 4.67±0.41mm for hypermetropics. Correlation between optic nerve and optic nerve sheath diameters was significant. Optic nerve diameter and optical axial length showed no significant differences. optical axial length revealed significant relation with optic nerve sheath diameter. There are significant differences between emmetropes and myopes (P 0.460) in the optical axial length, hypermetropes and emmetropes in the optic nerve diameter (P 0.304). The difference was significant in optic nerve sheath diameter between emmetropes on one hand and myopes and hypermetropes on the other hand (P 0.396) and (P 0.236) respectively. Myopes and hypermetropes exhibited (P 0.135). Conclusions: There were significant differences in: axial length between emmetropes and myopes, optic nerve diameter between emmetropes and hypermetropes, in optic nerve sheath diameter between all refractive states. These measurements can be taken to be a data base for Sudanese adult students.
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