8/7/2023 0 Comments Degenerative myopia retina![]() ![]() Over the last decade, intravitreal injection of anti-VEGF has become the first-line treatment for CNV showing promising results. In contrast to age-related macular degeneration, CNV lesions in pathological myopia may remain stable without affecting vision if left untreated 7. Myopic CNV tends to have a classic pattern of leakage on fluorescein angiography (FA) and appears as a plaque-like elevation with pigmented halo and sharply defined borders. Most myopic CNV is subfoveal or juxtafoveal with minimal subretinal fluid or exudate. 13 Whereas the CNV secondary to age-related macular degeneration (AMD) is usually in the sub-RPE space (type 1). Typically, myopic CNV is a small, flat, greyish, subretinal membrane that is less than 1 disc diameter in size 12 and is located between the neurosensory retina and retinal pigment epithelium (RPE) (type 2). SS-OCT shows a type 2 CNV with minimal subretinal exudation, a very thin choroid, and shisis-like changes on the left hand of the scan. Type 2 neovascularization (CNV above the RPE) is the most common manifestation of proliferation disease in myopic macular degeneration 8. ![]() Older patients seem to have a poorer prognosis regarding choroidal neovascularization as the involved area tends to be smaller and shallower in younger patients 5. Macular CNV is one of the most vision-threatening complications of degenerative myopia with an incidence of 5 to 10 percent in highly myopic patients and occurs most commonly in association with lacquer cracks or chorioretinal atrophy. It is thought that the disruption of the RPE-Bruch membrane-choriocapillaris complex allows entry of new choroidal neovascularization to the subfoveal area. They are present in about 5 percent of high myopes and can precede the apparition of choroidal neovascularization, subretinal hemorrhages, and geographic atrophy 5. Lacquer cracks are ruptures in the RPE-Bruch membrane-choriocapillaris complex seen as fine yellow lines radiating most often from the macular area and crisscrossing at the posterior pole. Fuchs spot is an elevated, circular, pigmented lesion at the macula occurring after a subretinal hemorrhage has been absorbed or as a choroidal neovascularization regresses leaving a subfoveal fibrous pigmented scar 8. Subretinal hemorrhages sometimes called “coin” hemorrhages may be intermittent and occur from choroidal neovascularization or secondary to posterior staphyloma causing bleeding from the choriocapillaris and often coincides with lacquer cracks 8. Further disease processes occurring in the posterior pole include macular hole, foveal retinoschisis, Fuchs spot, Lacquer cracks, subretinal hemorrhages, and choroidal neovascularization. It is an ectasia of the posterior sclera due to thinning and focal expansion and is best appreciated on A, B-scan ultrasound, or MRI. The hallmark of degenerative myopia is posterior staphyloma. Macular changes associated with pathological myopia: ![]() As the degenerative process progresses, a multitude of secondary ocular changes occurs principally thought to be due to mechanical stretching and involve the posterior pole, the peripheral retina, the vitreous, and the crystalline lens. Axial length elongation is also thought to be responsible for causing choroidal thinning called Lepto Choroid and is defined as a choroidal thickness of less than 20 microns in the subfoveal zone. Cupping of optic nerves with high myopia has the tendency to contract temporally which makes it difficult when assessing glaucomatous nerve damage 6. Tessellated fundus is typically associated with a crescent corresponding to an exposed area of the sclera that comes in contact with the papillary edges. As the stretching of the globe occurs, hypoplasia and scattering of the retinal pigment epithelium (RPE) allows for the choroidal vessels to be more visible and is called Tessellated fundus. The pathophysiology of Degenerative myopia begins with progressive anteroposterior elongation of the sclera with or without staphylomas (outpouching of the globe) 5. Studies performed in Singapore showed that higher levels of education, better housing, higher individual monthly income, and occupations requiring extensive near work increased the prevalence of myopia 4. The condition is known to be linked to environmental, genetic, and socioeconomic risk factors. The average rate of this condition is 1.7 to 2.1 percent worldwide but can reach up to 10 percent in certain areas of Asia. It is defined as a refractive error greater than -6.00 diopters and an axial length of more than 26 millimeters. It is the first cause of visual impairment in Japan 2. Degenerative myopia is one of the leading causes of visual impairment in the world occupying the seventh position in the United States and Europe 1. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |