الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
High myopia is a leading cause of visual loss especially in young populations.
Pathologic myopia is generally classified as a high myopic refractive error that is progressive and generally presents very early in childhood. Pathologic myopia is usually defined as spherical equivalent > 6.00 diopters or axial length >26.5mm.
The most common complication of high myopia is myopic retinopathy, which is a major cause of irreversible vision loss and blindness.
Myopic retinopathy is characterized by the presence of myopic choroidal neovascularization, posterior staphyloma, and chorioretinal atrophy in the posterior fundus.
With the advent of OCT, Myopic retinoshcisis has been increasingly recognized as important causes of vision decrease in eyes with pathologic myopia. Pannozzo and Mercanti proposed to unify all of the pathologic features generated by traction in the myopic environment under the name of myopic traction maculopathy.
Visual acuity loss occurs due to progressive atrophic changes such as diffuse atrophy, patchy atrophy, macular atrophy, posterior staphyloma, Myopic traction maculopathy and lacquer cracks and vision loss becomes more rapid with development of choroidal neovascularization.
High myopia is associated with profound changes in the choroid that are important in the pathogenesis of many important visually significant abnormalities. Advances in imaging have greatly increased our ability to visualize the choroid, providing an opportunity to better understand the choroid in health and disease. Because of its localization between the overlying pigmented RPE and the underlying opaque and rigid fibrous sclera, the choroid is difficult to visualize with conventional imaging. Methods employing light reflection or fluorescence generation are impeded by the pigment in the RPE and choroid. Conventional OCT is affected by the effects of melanin and also the scattering properties of the blood and blood vessels. The choroid is a deeper structure and the depth affects the detection sensitivity.
Today multimodal imaging, including high-speed fundus autofluorescence, angiographic studies of the two ocular circulations, optical coherence tomography, and 3-dimensional MRI imaging, has assisted in incorporating basic science knowledge of the disease in the clinical setting.
Recently introduced SS-OCT, Atlantis DRI 3D OCT by Topcon, Japan has revolutionised the diagnosis of retinal diseases and understanding the role of the choroid in some diseases, its advantages includes a longer wavelength allows deeper tissue penetration into the choroid and even sclera, higher imaging speed, larger scan window, and lower sensitivity roll-off with depth allow for larger scans up to 12 mm and the production of 3-dimensional (3D) images.SS-OCT allows better discrimination of the retinal layers. The demonstration of the anatomical changes of myopic traction maculopathy is even more clear, including distinct visualisation of the of the bridging elements. The superior image quality also allowed for visualisation of the vitreous, epiretinal membranes and ILM.
SS-OCT helped the diagnosis of new entities as dome shaped macula in eyes with high myopia. The central portion of the macula appeared to bow inward, unlike typical staphylomas in high myopia in which staphylomas bow outward.
The current study was conducted on 73 eyes of myopic patients with axial length more than 26mm who attended a private clinic in Tanta from January 2014 to November 2014 aiming to determine SS-OCT changes in Pathologic Myopia.
The study included 45 cases; of them 12 cases were males (26.7%) and 33 females (73.3%).
The age of the studied cases ranged from 6 to 82 years with a mean of 56.14 ± 11.12 years and a median of 58.0.
The Axial Length of the patients ranged from 26.23-34.62 mm, with a mean of 29.16 ± 1.53 mm.
The BCVA of the patients ranged from CF to 6/9.
The mean subfoveal choroidal thickness in studied patients was 61.34 ± 64.05μm.
Distribution of the studied eyes were 12.3% (9 eyes) had a myopic CNV.,17.8% (13 eyes) had a Dome shaped macula, 56.2% (41 eyes) had Myopic traction maculopathy with different forms.
Better visual acuity and thickest choroid was found with the group without chorioretinal atrophy, followed by Diffuse chorioretinal atrophy group, then the worst visual acuity and thinnest choroid was associated with patchy chorioretinal atrophy group.
8 eyes with only ILM detachment (11.0%), 5 eyes with Inner retinoshcisis ( 6.8%), 8 eyes with outer retinoshcisis (11.0%), 3 eyes with combined inner and outer retinoshcisis (4.1%), 10 eyes with lamellar macular hole( 13.7%), 4 eyes with Full thickness macular hole ( 5.5%), 2 eyes with myopic macular retinal detachment ( 2.7%) and 1 Case with myopic macular hole retinal detachment ( 1.4%).
In the current study we had 13 eyes with DSM (17.8% of the eyes),, none of our cases were complicated by a CNV, 2 eyes had ILM detachment, 2 eyes had inner retinoschisis, 2 eyes had Outer retinoshcisis, 1 eye had a full thickness macular hole,One eye had a serous retinal detachment.