الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 106 |  |  |
| | | from | 106 | | |
Abstract
makes IOP assessment less accurate. Optic disc morphology looks different in myopia and glaucomatous changes are masked by tilted disc and peripapillary atrophy. Visual field defects may be thought to be caused by myopic fundus, posterior staphyloma or choroidal atrophy rather than glaucomatous changes.
In glaucoma, approximately 40% of RNFL is lost before visual field defect becomes evident. And so, thickness of RNFL is an important indicator in the diagnosis and monitoring of optic nerve diseases. In that sense, accurate and reliable measurements of RNFL thickness and detecting its normal limits are very importance in early diagnosis of glaucoma.
RNFL thickness and optic disc parameters measurement vary with age, IOP, AL, lens nuclear color, and signal strength.
There is reduction in the NFL thickness with increasing the axial length. A mean RNFL decrease of approximately 1.1 μm per minus diopter. There is a mild decrease in the segmented RNFL thickness associated with decreasing signal strength.It was found that for each unit of decrease in signal strength, the average RNFL thickness had a corresponding decrease of 2 μm.
Summary
74
Another factor complicating the measurement of the NFL is that the normative databases used by SD-OCT manufacturers have populations with refractive errors only between -5.00 and +5.00 D.
We aimed to study the effect of using a contact lens with the same spherical equivalent on the signal strength, RNFL thickness and other optic disc measurement (cup volume, disc area and rim area).
Our study included myopic patients with axial lengths of more than 25.5 mm.
It included (25) eyes of (18) myopic patients.
After full clinical examination of subjects, Axial length measured by IOL master then IOP is measured by applanation tonometry.
Spectral-Domain Optical Coherence Tomography used for measurement of macular thickness, peripapillary RNFL thickness in all quadrates, signal strength, cup volume, disc area and rim area, one scan before contact lens the application and other scan after the application of contact lens with the same spherical equivalent.
We found that the average thickness of RNFL has a significant increase after contact lens application (P value 0.001). The superior, inferior and nasal RNFL thickness show statistically significant changes after contact lens application (P value ≤ 0.05). Regarding temporal RNFL thickness there is no significant differences.
Also, we found that signal strength improved significantly after contact lens application (p<0.001). Regarding cup volume, disc area, rim area, no significant differences was noticed.
Summary
75
Finally, the use of a contact les with the same spherical equivalent statistically improves signal strength and consecutively increases the main RNFL thickness in myopic patients who are glaucoma suspects and enables accurate diagnosis of glaucoma in myopic patients.