Marmor M F
Department of Ophthalmology, Stanford University School of Medicine, California 94305.
Eye (Lond). 1990;4 ( Pt 2):340-4. doi: 10.1038/eye.1990.46.
Experimental work shows that subretinal fluid is removed both by active transport across the retinal pigment epithelium (RPE) and by passive hydrostatic and oncotic forces that work most effectively when the RPE barrier has been damaged. The retina will stay attached whether or not the RPE is intact--but retinal function requires the RPE barrier and thus active transport is the primary mechanism of subretinal fluid control. RPE fluid transport is normally limited by the retina (which resists water flow from the vitreous) but can be quite powerful when a reservoir of subretinal fluid is present. Clinical serous detachments are unlikely to form solely as a result of small RPE defects or leaks, since the active and passive transport systems for removing subretinal fluid are both so strong. It is suggested that the primary pathology in most serous retinopathy is a diffuse metabolic or vascular abnormality of RPE fluid transport, and that RPE defects or leaks are necessary but only secondary components of the disease. Several hypotheses for removing subretinal fluid therapeutically are considered in terms of their physiology. The subretinal space between the photoreceptors and the retinal pigment epithelium (RPE) is the remnant of the embryonic optic vesicle. In the developed eye the subretinal space is of minimal size, but no tissue junctions form across it and it can re-open under pathological conditions of retinal detachment. In a sense, the title of this paper is misleading since normally there should be no subretinal fluid to control. However, ocular mechanisms are necessary to prevent an accumulation of fluid, and to remove it under conditions of stress or disease.
实验研究表明，视网膜下液可通过跨视网膜色素上皮（RPE）的主动转运以及被动流体静力和渗透压作用而被清除，当RPE屏障受损时，被动作用最为有效。无论RPE是否完整，视网膜都会保持附着状态——但视网膜功能需要RPE屏障，因此主动转运是视网膜下液控制的主要机制。RPE的液体转运通常受视网膜限制（视网膜可抵抗来自玻璃体的水流），但当存在视网膜下液蓄积时，其作用可能会相当强大。临床浆液性脱离不太可能仅由微小的RPE缺陷或渗漏导致，因为清除视网膜下液的主动和被动转运系统都很强。提示大多数浆液性视网膜病变的主要病理改变是RPE液体转运的弥漫性代谢或血管异常，RPE缺陷或渗漏是必要的，但只是该疾病的次要成分。从生理学角度考虑了几种治疗性清除视网膜下液的假说。光感受器与视网膜色素上皮（RPE）之间的视网膜下间隙是胚胎视泡的残余部分。在发育成熟的眼睛中，视网膜下间隙尺寸极小，但其间没有组织连接，在视网膜脱离的病理情况下它可能重新开放。从某种意义上说，本文的标题具有误导性，因为正常情况下不应存在需要控制的视网膜下液。然而，眼部机制对于防止液体蓄积以及在应激或疾病状态下清除液体是必要的。
