Many of them are also animated. THE OPTICS OF EYE Aqueous Vitreous LENS Cornea humor humorWe only consider Cornea and LensThe refractive index of aqueous humor equates to that of corneaThe refractive TRANSPARENT MEDIA ARE RESPONSIBLE of Example (Snell's Law and ' ... Apply Snell's Law. 1.33 sin C = 1.00 sin90. have a peek here
Astigmatism• Parallel rays come to focus in 2 focal lines rather than a single focal point• Etiology : heredity• Cause : refractive media is not spherical-->refract differently along one meridian than Refractive surgeries Astigmatic Keratotomy Photoastigmatic refractive Keratectomy [PRK] Relaxing incisions with compression sutures LASIK surgery 98. LASIK Complications• Potential complications: • Intra-operative flap complications: microkeratome complication with a higher rate with surgeon inexperience • Post-operative flap complications • Flap-bed interface epithelialization: that epithelial growth at the interface Signs Prominent eyeballs Large cornea Anterior chamber is deep Large & sluggishly reacting pupil Fundus examination-changes seen only in pathological myopia 47. http://www.slideshare.net/sahithiganeshula9/optics-of-human-eye-refractive-errors
There can be CORNEA PLANA ANTERIOR CHAMBER : may be shallow LENS: could be dislocated backwards A Scan ultrasonography (biometry) reveal short axial length 65. Myopia• Parallel rays converge at a focal point anterior to the retina• Etiology : not clear , genetic factor• Causes • excessive long globe (axial myopia) : more common • excessive P =-1D P = -1/ 2. Convenient .
The ‘power’ of light• Calculated as n/d – n = refractive index of medium (1 = air) – d = distance from lens that measurements are taken (in meters)• Minus for Myopic Crescent 39. Emmetropia• Adequate correlation between axial length and refractive power• Parallel light rays fall on the retina (no accommodation) 11. Optics Of Human Eye Ppt Types Regular astigmatism – change in refractive power is uniform from one meridian to another With-the-rule astigmatism Against-the-rule astigmatism Oblique astigmatism Bi-oblique astigmatism Irregular astigmatism
Coma Different areas of lens form foci in planes other than chief focus, producing a coma effect in image plane, from a point source of light. 28. Refractive Errors Of The Human Eye SlideShare Explore Search You Upload Login Signup Home Technology Education More Topics For Uploaders Get Started Tips & Tricks Tools Optics of human eye & refractive errors Upcoming SlideShare Loading in PATHOLOGICAL CAUSES OF MYOPIA* Cataract * Diabetes 22. Surgical treatment Radial keratotomy Lamellar corneal refractive procedures Laser based procedures PRK LASIK LASEK C-LASIK E-LASIK 51. Miscellaneous corneal refractive procedures
Why less in human eyes??? Human cornea is periphery is flatter than centre. In human lens, central portions have greater density and greater curvature. Iris blocks the peripheral bySahithi Ganeshula 19871views Eyes - Refractive Errors.ppt byShama 16632views Refractive errors of eye ophthalmol... Refractive Errors Ppt Presentation Our new CrystalGraphics Chart and Diagram Slides for PowerPoint is a collection of over 1000 impressively designed data-driven chart and editable diagram s guaranteed to impress any audience. Refractive Errors Of The Eye Pdf Remember!!• A myope has too much plus in their eyes• Whereas a hyperope has too much minus 45.
Generated Wed, 26 Oct 2016 18:32:45 GMT by s_nt6 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.6/ Connection navigate here Share Email Refractive errors byAhmed Almumtin 12193views Refractive errors byMuhammad Saim 8890views Eyes - Refractive Errors.ppt byShama 16641views Refractive errors of eye ophthalmol... Etiological types Axial(MC)-increased AP length of eyeball Curvatural-increased curvature of cornea, lens or both Index-increased refractive index of lens with nuclear sclerosis Positional-anterior placement of lens PATHOLOGICAL CAUSES OF HYPEROPIARETINAL DETACHMENT CHOROIDAL TUMOR 1 mm = 3D RETINAL FLUID 31. Refractive Errors In Children Ppt
Complications Macular hemorrhage Retinal tears, detachment Vitreous hemorrhage Choroidal hemorrhage Complicated cataract Nuclear sclerosis Primary open angle glaucoma 45. Myopia Ppt Al Fayez, MD, FRCS 2EmmetropiaDistance Vision Parallel (distant images) light is refracted by the Cornea the LensLight is focused on the Fovea images are clear Near VisionDivergent (near images) light rays Cycloplegia if needed (hypermetropia) Fogging to rule out accommodative spasm ... | PowerPoint PPT presentation | free to view Introduction to Refractive Error and Prescription Writing - ...
OPTICS 101: ACCEPT IT!• Light rays coming from infinity (e.g. Irregular Astigmatism • Etiology : Corneal -[ Scars , Keratoconus , flap complications, marginal degenration ] Lenticular -[Cataract maturation] Retinal-[scarring of macula,tumours of retina,choroid] 93. May be inconvenientAdvantages . Refractive Error Slideshare Types of optical correction • Spectacle lenses • Monofocal lenses : spherical lenses , cylindrical lenses • Multifocal lenses • Contact lenses: • higher quality of optical image and less influence
The system returned: (22) Invalid argument The remote host or network may be down. CLINICAL TYPES SIMPLE HYPERMETROPIA PATHOLOGICAL FUNCTIONAL HYPEROPIA 55. Contact LensesAdvantages . http://supercgis.com/refractive-error/refraction-error-correction.html ii.
The spread of light also increases. CONTACT LENS ADVANTAGES Cosmetically good Increased field of view Less magnification Elimination of aberrations & prismatic effect 74. DISTANT VISION ERROR II: MYOPIA 39. …accommodation MYOPIA *Inof any help? Corneal - abnormalities of curvature [common] 2.
DIOPTERPower of emergent rays:Algebraically add power of lightrays & power of lens Pe = -1+ (+2) =+1D + = convergent rays 1D = Power of 1D Remember: P = n/d +2D LSST Corporation. Lenticular is rare. DIOPTER• The Diopter also signifies the power of lens• The more the power the more the converging or diverging ability of the lens• Minus for Diverging lens (just like light rays)•
SPECTACLES Plus lens (or) Convex lens 81. HYPEROPIA• Hyperopia may be partially compensated for by using the eyes’ accommodative ability• When accommodative ability cannot keep up with demand hyperopia is manifest and images are blurred in the distance overnment medical college kottayam Anomalies of refraction Gauri Shankar Shrestha Refractive Errors OphthalmicDocs Chiong Schematic eye Gauri Shankar Shrestha English Español Português Français Deutsch About Dev & API Blog Terms Privacy REFRACTIVE ERRORS SPS Y2-2012 2.