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Doctor insights on: Camera And Human Eye Comparison

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How can the human eye accommodate for viewing very close and very distant objects?

How can the human eye accommodate for viewing very close and very distant objects?

Natural: The lens of the eye is connected to a muscle behind the iris is called the ciliary body. When the ciliary body contracts, the fibers connecting the lens called the zonules relax, & the lens fattens. When the ciliary body relaxes the fibers tighten & the lens flattens. This change in shape causes a change in the way light is bent through the lens and this changes the focusing for distance & near. ...Read more

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What are the uses and?Side effects of oct (optical coherence tomography) test of eye?

What are the uses and?Side effects of oct (optical coherence tomography) test of eye?

Versatile: The oct is a magnificent piece of equipment that is capable of many uses. It can be used in glaucoma to measure the size of the angle and to measure the thickness of the layer of tissue around the optic nerve. It is also useful in many different types of retinal disease. There are no side effects to the test itself, in some instances, your eye may have to be dilated to take it. ...Read more

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Is optos ultra-wide field retinal imaging more efficient than indirect ophthalmoscopy to see large details of the retina?

Is optos ultra-wide field retinal imaging more efficient than indirect ophthalmoscopy to see large details of the retina?

Efficiency-accuracy: Efficiency, speed, ease of use are attributes of optos, but detailed, high magnification ; dynamic indirect ophthalmoscopy by the eye md is better for careful discriminative diagnoses. Sorry, i don't want to be replaced (yet) by a camera! i've never been able to replace my careful examination of the retina with indirect ophthalmoscopy by an image, except by sd-oct which is excellent. ...Read more

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Why don't physiology books show refraction at the anterior surface of the cornea?

Why don't physiology books show refraction at the anterior surface of the cornea?

Too specific.: A general physiology book already has a lot to cover without delving into physiologic optics. If you want to dig deeper, check out general optics texts to understand basics like indices of refraction, followed by eye anatomy and physiology texts. The bscs series volume on cornea is helpful. Finally, texts about corneal topography, higher-order aberrations, and lasik would be fun. War eagle! ...Read more

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I have a refractive error of -5.75 in both eyes (myopia & astigmatism) and floaters in both eyes. Is a pupil dilation better than the digital retinal?

I have a refractive error of -5.75 in both eyes (myopia & astigmatism) and floaters in both eyes. Is a pupil dilation better than the digital retinal?

Yes: Nothing beats the chance to get a good look at the peripheral retina when there is an onset of new floaters. Dilation is a bit of an annoying pain but is recommended in this circumstance. You are, hopefully, seeing an ophthalmologist. ...Read more

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YAG iridotomy at 12 o'clock position. Have ghost images in lower field of vision. Looks kind of like a line/crescent of light Will these resolve?

YAG  iridotomy at 12 o'clock position.  Have ghost images in lower field of vision.  Looks kind of like a line/crescent of light Will these resolve?

Most often yes: Sometimes no, if it does not, please look into a corneal tattoo (rarely needed but works very well to block the extra light coming through or colored contact lens. ...Read more

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Is something 10 angstroms in diameter large enough for the human eye to discern?

Is something 10 angstroms in diameter large enough for the human eye to discern?

Not even close: 10 angstroms = 1 nanometer. The smallest thing the human eye can see is about 0.1 mm which is 100, 000 nanometers or 1 million angstroms! angstroms are really really small! ...Read more

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Are eye measurements done as part of the regular eye exam?

Are eye measurements done as part of the regular eye exam?

Regular eye exam: Yes, your eye care professional will at minimum take measurements of your visual acuity (e.g. 20/20) and eye pressure. Your refraction (vision correction) will also be measured if you are seeing a general practitioner. The remainder of the exam will focus on any abnormalities, and if present, they will measure them as well. For example, if you have cataracts, they will be given a "grade". ...Read more

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How can the curved cornea and lens of the human eye affect the light entering the eye?

How can  the curved cornea and lens of the human eye affect the light entering the eye?

Focusing: The cornea and the lens are actually both types of lenses that focus the light coming into the eye. The cornea has about 40 diopters of focusing power and the lens 20 diopters. ...Read more

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19 male. If you cover each eye individually and still see a faint verticle ghost image on both eyes is the monocular or binocular?

19 male. If you cover each eye individually and still see a faint verticle ghost  image on both eyes is the monocular or binocular?

Monocular: If you see an image in each eye while one eye is closed then its monocular. If the image only has faint line or double with both eye open then its binocular. Binocular double vision goes away when you cover one eye. ...Read more

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Can opthamologists tell the difference between hyaline cendensation and vitreous bodies and eye floaters w/dilated eye exam? Same prognosis for both?

Can opthamologists tell the difference between hyaline cendensation and vitreous bodies and eye floaters w/dilated eye exam? Same prognosis for both?

A dilated exam can: Differentiate between a vitreous floater, vitreous detachment and hyaloid opacification. The etiology (cause) for these entities can vary and thus patient history is important. The prognosis can also be variable depending upon the diagnosis and cause of each entity listed. For example, hyaloid pathology could be secondary to inflammation and carries a different set of issues. A good dilated is rec. ...Read more

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Explain how eye can accommodate for viewing very close and distant objects?

Explain how eye can accommodate for viewing very close and distant objects?

Lens power increases: The focusing muscle of the eye ( ciliary body) contracts lowering the tension on the lens from fibers (zonules) that connect it to the circumferance of the lens the lens gets thicker and increases in power focusing light rays from near objects on the retina. When it relaxes the opposite happens the lens thins and distant light rays are put in focus. ...Read more

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I'm 20yo. In pics I have red eye effect in both eyes but the pupil is more bright red in left eye and greater in diameter as compared to the right eye?

Anisocoria: Pupil size inequalities (anisocoria) requires an eye exam, and it should be done right away. There are important things to rule out to ensure that your pupils are normal. About 20% of individuals have this normally (physiologic), whereas others may have it on the basis of disease or medications. The latter causes: 3rd nerve palsy, horner's, aidies, certain drugs (eg eye meds), injury, inflamed i. ...Read more

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Can coloured leds damage the eye simply because only a tight frequency spectrum of light is shinning on your eye and we evolved with full sun spectra?

Can coloured leds damage the eye simply because only a tight frequency spectrum of light is shinning on your eye and we evolved with full sun spectra?

No damage : Bright lights like leds can temporarily bleach out your vision, but won't damage your eyes. The sun's rays have considerable energy along with brightness and can permanently damage your vision--never look directly at the sun. ...Read more

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Can coloured leds damage the eye simply because only a tight frequency spectrum of light is shinning on your eye and we evolved with the sun's spectra?

Can coloured leds damage the eye simply because only a tight frequency spectrum of light is shinning on your eye and we evolved with the sun's spectra?

No damage : Bright lights like leds can temporarily bleach out your vision, but won't damage your eyes. The sun's rays have considerable energy along with brightness and can permanently damage your vision--never look directly at the sun. ...Read more

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Pain to move left eye, blurry vision lower 1/2 visual field that eye only (is like a greasy film over bottom 1/2 of eye). Blood pressure perfect?

Pain to move left eye, blurry vision lower 1/2 visual field that eye only (is like a greasy film over bottom 1/2 of eye). Blood pressure perfect?

Optic neuritis: You need to see an ophthalmologist asap. The biggest concern in a woman your age would be optic neuritis. This would explain your symptoms best. You need a thorough exam by an ophthalmologist first the ophthalmologist may order an MRI or have you see a neurologist depending on the findings. ...Read more

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Why can't they make a progressive eye glass lens where the vision for intermediate and reading is wider... Even to the edge of the frame?

Why can't they make a progressive eye glass lens where the vision for intermediate and reading is wider... Even to the edge of the frame?

Not optically done: Progressive lenses have two issues: 1) giving a continuous grind to allow for several distances of clear vision and 2) cosmetic optics so that the continuous grind is not evident. They could make a lens with a much larger optic as you are hoping for but this would produce obvious optical distortions that would make the lens look odd and would not reach the edge of the lens anyway. ...Read more

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How does the mirror affect the eye chart in a visual acuity test?

Lengthens light path: Most offices do not have a 20 foot lane. But standards and available charts are made to reflect a 20 foot lane. The way to handle this is to use mirror (s) to reflect the image the proper distance to approximate a 20 foot lane. The letter images can also be enlarged or diminished as needed but this will change the standardization. A 20 foot light path is the standard. ...Read more

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