Myopic Macular Retinoschisis
Myopic macular retinoschisis is considered to be a representative pathology which OCT contributed on its diagnosis and the establishment of treatment. It is not uncommon and is found in 9–34 % of highly myopic eyes with posterior staphyloma. During a natu
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Kyoko Ohno-Matsui
16.1
Myopic Retinoschisis and Associated Lesions
In 1997, Takano and Kishi first identified and reported that the foveal retinal detachment and macular retinoschisis (MRS) were observed in highly myopic eyes before developing macular hole retinal detachment by using OCT [1]. This finding provided a clue why macular holes in highly myopic eyes tend to develop retinal detachment unlike idiopathic macular holes in non-myopic eyes. The schisis was found to occur in the outer retinal layer unlike congenital macular retinoschisis; however, the morphological details of the separated retina were unclear at this point mainly due to a limited resolution of OCT [1–3]. With the advent of OCT, MRS has been increasingly recognized as important causes of vision decrease in eyes with pathologic myopia. MRS is found in 9–34 % of highly myopic eyes with posterior staphyloma [1, 2, 4]. Despite numerous publications on this condition, no clear definition of MRS has been found in the literature. The hallmark of MRS is the appearance of schisis of the retinal layers, most commonly in the outer plexiform layer (outer retinoschisis) (Fig. 16.1) [5–7]. In minority cases, the appearance of schisis may occur within more internal retinal layers (inner retinoschisis) with detachment of the internal limiting membrane (ILM) (Fig. 16.1) [7, 8]. Although the terminology “myopic retinoschisis” still prevails, it is now believed (due in part to improved imaging with recent OCT) that eyes with myopic retinoschisis have traction, resulting in elongation of Henle’s nerve fiber rather than a splitting of the retina. Thus, MRS is a totally different condition from congenital
K. Ohno-Matsui, MD, PhD Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan e-mail: [email protected]
macular retinoschisis, which is a splitting of the retinal nerve fiber layer from the rest of the sensory retina disrupting a synaptic transfer between bipolar cells and ganglion cells. A lack of central scotoma in eyes with MRS supports this concept. Pannozzo and Mercanti [4] proposed to unify all of the pathologic features generated by traction in the myopic environment under the name of myopic traction maculopathy.
16.2
Clinical Features of MRS
Most of the patients with MRS may be relatively asymptomatic especially while the eyes do not develop more serious complications like full-thickness MH or foveal RD [2], and MRS may persist for many years before affecting vision significantly. Vision loss attributed to MRS has been associated with the development of foveal RD and/or macular holes in most cases. The best-corrected visual acuity (BCVA) of the patients with MRS ranged widely from 20/40 to 20/200 [2, 9]. Some patients complain metamorphopsia or distorted vision before the visual acuity is decreased. However, what makes difficult for clinicians to suspect the MRS is that some of the patients with MRS do not notice the change in vision [2], due to coexisting myopic r
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