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Medical Forum / General / Vision / August 2005Drusen
Can drusen be seen by the patient? Don W. no. drusen of the retina are an accumulation of waste materials. they can be seen by an observer looking at the retina, but not by the patient. drusen of the optic nerve head can affect the visual field of the patient, and while they can't be "seen" by the patient, the patient may get visual field defects that are usually only noticable using a field analyzer unless they get quite severe. > no. drusen of the retina are an accumulation of waste materials. they > can be seen by an observer looking at the retina, but not by the > patient. drusen of the optic nerve head can affect the visual field of > the patient, and while they can't be "seen" by the patient, the patient > may get visual field defects that are usually only noticable using a > field analyzer unless they get quite severe. The retina can be viewed by the patient by the entopic effect. Would that not view drusen that is on the surface of the retina? > The retina can be viewed by the patient by the entopic effect. Would that > not view drusen that is on the surface of the retina? Which entopic effect? Wiggling a light source enables you to see the vessel pattern (purkinje's tree) but the vessels are in front of the retina and cast a shadow. Drusen are behind the sensory layer and any retinal stimulation would be entirely static and therefore filtered out. -MT >> The retina can be viewed by the patient by the entopic effect. Would >> that not view drusen that is on the surface of the retina? [quoted text clipped - 6 lines] > Drusen are behind the sensory layer and any retinal stimulation would be > entirely static and therefore filtered out. Drusen can exist on the surface of the retina, as seen in fundus photographs. So they should be able to be seen. The entopic effect I am talking about is one where the oscillating light hits and is reflected off the inside of the eye. > Drusen can exist on the surface of the retina, as seen in fundus > photographs. So they should be able to be seen. Choroidal vessels are also visible in fundus photos, but they are well behind the retina. Drusen occur in Bruch's membrane, the basement membrane for retinal pigment epithelium. Drusen can elevate or distort the sensory retina but they aren't "on the surface" with retinal vessels and they cast no shadow you could perceive, like the vessels do. > The entopic effect I am talking about is one where the oscillating light > hits and is reflected off the inside of the eye. I'm pretty sure you wouldn't see drusen that way. -MT In some the OCT's that I have seen, drusen can lift the retinal structure above it. So maybe one (like me) is not seeing drusen directly, but some weird presence of it's elevation, (moving shadows from the hill peaks) since it occupies space. This spotted image seems to be at a different position due to the incoming light. That is, I can pick up the vascular structure at one position and the "drusen" at another. This effect is not in the anterior portion of the eye or within the vitreous, it doesn't move fast with small angular positions of the source. It is possible that it maybe something else besides drusen (or its effect). In looking at pictures of (for example) craters, they appear elevated or depressed depending on the light source. This "drusen" array to me appears depressed. Since this is all subjective viewing, I can't be sure of what I'm seeing, and since, as you and others have pointed out, it lies beneath the retinal structure (non-viewable) . But, for some reason, I do see it, and I do believe it is drusen. I've done a Pubmed on this symptom and have come up with zip. So....... Thanks for the inputs. >> Drusen can exist on the surface of the retina, as seen in fundus >> photographs. So they should be able to be seen. [quoted text clipped - 13 lines] > > -MT > In some the OCT's that I have seen, drusen can lift the retinal structure > above it. So maybe one (like me) is not seeing drusen directly, but some > weird presence of it's elevation, (moving shadows from the hill peaks) If I jumped the gun, Stacy did too... :) Most doctors will answer "no" because they think you're asking "is it a reliable way to detect drusen." No it is not. But assuming concrete evidence (you're seeing the same distribution pattern entopically as in the fundus photos) then here's an explanation. I don't recall pictures of drusen growing backwards. They're typically flat-bottomed and growing forward in micrographs, as if the photoreceptor layer offers less resistance, which it does. Drusen are translucent, and the concave-up profile makes them look like little magnifying lenses. It's reasonable that they should play light tricks back into the sensory retina when the source wiggles. It isn't reasonable to assume everyone with drusen can appreciate them entopically, but I'll be trying it tomorrow. Thanks! :) -MT >> In some the OCT's that I have seen, drusen can lift the retinal >> structure above it. So maybe one (like me) is not seeing drusen [quoted text clipped - 4 lines] > because they think you're asking "is it a reliable way to detect drusen." > No it is not. Not asking if it is reliable. Just if it is a way. > But assuming concrete evidence (you're seeing the same distribution > pattern entopically as in the fundus photos) then here's an explanation. > > I don't recall pictures of drusen growing backwards. I meant that as the light hits them, they can look like mounds or depressions, depending. Just like pictures of moon craters. Turn them (the pictures) around and they are mountains (or mesas). > They're typically flat-bottomed and growing forward in micrographs, as if > the photoreceptor layer offers less resistance, which it does. [quoted text clipped - 9 lines] > > -MT Good luck, I wish there was a better way of explaing this effect. Don W > It isn't reasonable to assume everyone with drusen can appreciate them > entopically, but I'll be trying it tomorrow. Thanks! :) Does status exist? >That is, I can pick up the vascular structure at >one position and the "drusen" at another. I don't know why that would be. The same obliquely incident light movement should "light up" any structure capable of casting a shadow at the same time/position. Like why would a setting sun cast a shadow from an ant hill but not from a fire hose at the same time? > This effect is not in the >anterior portion of the eye or within the vitreous, it doesn't move fast >with small angular positions of the source. How do you know it's not in the vitreous? Your "doesn't move fast" comment makes me believe that it is indeed in the vitreous, because anything on the retina will move exactly as fast as any eye movement, and to the same extent, while vitreous floaters always have a little lag with eye movement, and never move quite as quickly as the associated eye movement. w.stacy, o.d. > Drusen can exist on the surface of the retina, as seen in fundus > photographs. So they should be able to be seen. The entopic effect I am > talking about is one where the oscillating light hits and is reflected off > the inside of the eye. No, they cannot, because they cannot cast a shadow that is capable of moving across the surface of the retina. The only reason you can visualize your own retinal vasculature is by shifting the shadows cast by the vessels to different positions via special lighting arrangements. The retina can only detect changes in light intensity or changes in image position. w.stacy, o.d. See input to Mike... thanks. >> Drusen can exist on the surface of the retina, as seen in fundus >> photographs. So they should be able to be seen. The entopic effect I am [quoted text clipped - 9 lines] > > w.stacy, o.d. |
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