Low vision aid
-
Upload
sssihms-pg -
Category
Health & Medicine
-
view
1.549 -
download
18
Transcript of Low vision aid
![Page 1: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/1.jpg)
PRESENTED BY MODERATOR
DR.R.HARIPRIYA PG IN OPHTHALMOLOGY SSSIHMS
DR.AMIT CHABRA DEPT OF OPHTHALMOLOGY
![Page 2: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/2.jpg)
Visual Disorder-Anatomical changes Visual impairment-Functional changes Visual disability-Skills &abilities affected Visual handicap-Socio economic
consequences.
![Page 3: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/3.jpg)
Legal Blindness◦ Best corrected distance visual acuity of CF-1MT
or worse in better eye◦ Visual field of 10 degrees or less in the better
eye Low Vision
◦ Best corrected visual acuity worse than 20/60 in the better eye(or) visual field of less then 10⁰ from the point of fixation.
![Page 4: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/4.jpg)
1)Moderate visual impairment- best corrected VA less than 6/18 to 6/60.
2)Severe visual impairment- best corrected visual acuity of less than 6/60 to CF-3MTS (or) visual field diameter of 20⁰ or less.
3)Profound visual impairment- best corrected visual acuity of less than CF-3MTS to CF-1MT or visual field diameter of 10⁰ or less.
![Page 5: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/5.jpg)
4)Near total vision loss- best corrected visual acuity of CF-1MT or less.
5)Total blindness- no perception of light.
![Page 6: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/6.jpg)
Loss of central vision (visual acuity)
Loss of peripheral vision (visual field)
Glare and contrast
![Page 7: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/7.jpg)
Difficulty readingProblems writing/ completing paperwork
Inability to recognize distance objects and faces
![Page 8: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/8.jpg)
Need for additional lightingProblems with glare Increased adjustment to changes in illumination
Visual discomfort and fatigue
![Page 9: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/9.jpg)
CLOUDY MEDIA: uncorrected refractive errors, dry
eyes,corneal dystrophies,keratoconus,corneal scarring from H.simplex,traumatic mydriasis,cataract,vitreous hemorrhage & posterior uveitis.
![Page 10: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/10.jpg)
Location of scotoma important! Generalized loss of visual field difficult to compensate for
Mobility and independent travel
Reading may require adaptations
![Page 11: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/11.jpg)
CENTRAL FIELD DEFICITS: Macular degenerations, macular hole,
diabetic macular edema and ischemia, myopic degeneration, toxoplasmosis , histoplasmosis, phototoxicity, drug toxicity, focal or grid laser for CSME, iatrogenic central and paracentral scotoma.
![Page 12: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/12.jpg)
PERIPHERAL FIELD DEFICIT: Retinal dystrophies, RP , RD , PDR,
Glaucoma,Ischemic optic neuropathy,Stroke,Trauma,Tumour,Panretinal laser photocoagulation.
![Page 13: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/13.jpg)
History/ intake Visual acuity Visual field testing Pupils Extraocular muscle testing Refraction Color vision and Contrast Testing Ocular Health
![Page 14: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/14.jpg)
![Page 15: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/15.jpg)
![Page 16: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/16.jpg)
Confrontation Arc perimeter Automated perimetry Goldmann perimetry
![Page 17: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/17.jpg)
Ishihara Color Vision Testing Made Easy D-15 Pelli-Robson Vistech Contrast System Mr. Happy
![Page 18: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/18.jpg)
![Page 19: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/19.jpg)
![Page 20: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/20.jpg)
Enlarges image on retina to stimulate more retinal cells
Can be achieved in many ways◦ Relative Distance◦ Relative Size◦ Optical / Angular◦ Electronic
![Page 21: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/21.jpg)
1)Magnifying spectacles2) Hand magnifiers 3)Stand magnifiers4)Telescopes5)Electronic magnifiers
![Page 22: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/22.jpg)
Macular Degeneration
Glaucoma Diabetic
Retinopathy Stroke/ brain injury Retinitis
pigmentosa Optic Nerve disease
Albinism Nystagmus Cortical Visual
Impairment
![Page 23: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/23.jpg)
Hand held telescopes Mounted telescopes Electronic systems
![Page 24: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/24.jpg)
Spectacles◦ Prismatic ½ eyes◦ Full-field microscopes
Magnifiers◦ Hand held or Stand held◦ Illuminated or non-illuminated
Telemicroscopes Electronic Devices
![Page 25: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/25.jpg)
Magnifying devices work by increasing the angle subtended by the object at the eye thus producing an enlarged retinal image(angular magnification).
MP= RETINAL IMAGE WITH USE OF INSTRUMENT/RETINAL IMAGE WITH OUT USE OF INSTRUMENT.
![Page 26: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/26.jpg)
Convex lenses are used as hand held magnifiers or stand magnifiers.Here the object is located between the first principal focus and lens gives virtual,erect,magnified image for the eye.
As the object moves nearer to first principal focus,the virtual image becomes larger and is situated futher from the eye.
![Page 27: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/27.jpg)
Field of vision depends upon size or aperture of the lens and on eye lens distance.
Greater the eye lens distance smaller the field of vision.
Conex cylindrical lenses which has no refractive power or only a low converging power in its long axis and high converging power in cross section provides vertical magnification of powers.
![Page 28: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/28.jpg)
Galilean telescopes composed of convex objective and concave eye piece, seperated by difference of their focal length.
It produces a errect, magnified image. It mainly acts by increasing angle
subtended by the object at the eye.
![Page 29: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/29.jpg)
Astronomical(keplers) telescopes consists of two convex lenses seperated by sum of their focal lengths.
This system produces a magnified,inverted image.
Prisms or mirrors are used to invert the image.
![Page 30: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/30.jpg)
Types & designs- 1)Binocular spectales2) Monocular spectacles-standard aspheric
lenses from +4D to +20D in 2D increments -specially designed microscopic and double lenses
from +24D to 60D.3)Half eye glasses are preferable because they reduce
the weight,thickness & size for near vision.
![Page 31: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/31.jpg)
![Page 32: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/32.jpg)
![Page 33: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/33.jpg)
4)High add bifocals or high add trifocals can be used to read large prints at great distance.
![Page 34: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/34.jpg)
Cosmetically acceptable Comfortable and easy to use Both hands are free Field of vision is large Simultaneous vision for near & distance
vision is possible Less expensive
![Page 35: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/35.jpg)
Spherical aberations are created with high plus lenes unless aspherical lenses are used.
Short focal length of high plus lenses makes the patient hold print close to the eye thereby illumination decreases.
![Page 36: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/36.jpg)
Mainly used for near vision problem Does not require accomidation to see
the image Indications- -for spot or short time tasks in
patients with field of vision reduced to 10⁰ or more.
-as auxiliary lens for finer jobs.
![Page 37: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/37.jpg)
![Page 38: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/38.jpg)
Available from +4 to+40D Their magnification is variable,since the
power varies with distance between the object and focal point of magnifier.
These has wide field of vision,light weight, self contained illumination.
![Page 39: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/39.jpg)
Working distance is more Accomidation is not required for reading Easy to view eccentrically
![Page 40: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/40.jpg)
Hand is not free. Inconvenient and tiring Reduced field of vision when compared to
spectacles. Not useful in the absence of manual
dexterity. Need to be held at correct distance to
obtain maximum power.
![Page 41: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/41.jpg)
Types & design- -available in two forms 1)Prefocused 2)Focusable -range in power from +4 to +60D. -self illuminated devices available which
prevent glare. -requires some accomidative effort.
![Page 42: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/42.jpg)
![Page 43: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/43.jpg)
![Page 44: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/44.jpg)
Technically simple as they are prefocused and rest on a rigid mount.
Choice for patients with hand tremors.
![Page 45: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/45.jpg)
Small field of vision Difficult to use if surface is not flat.
![Page 46: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/46.jpg)
TYPES & DESIGNS: Monocular telescopes- easy to carry and
use
Binocular telescopes- offers a good grip, cumbersome to carry. If one eye is worse than other, these offers no improvement in viewing quality.
![Page 47: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/47.jpg)
![Page 48: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/48.jpg)
![Page 49: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/49.jpg)
![Page 50: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/50.jpg)
![Page 51: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/51.jpg)
![Page 52: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/52.jpg)
Telescopes can be either hand held or spectacle mounted.
The poorer the vision, stronger is the power of the telescope required.
The maximum power useful for hand held type is 8X and for spectacle type is 4X.
![Page 53: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/53.jpg)
Telescopic spectacle systems are used for intermitent basis for sedentary distance viewing.
Telescopic systems are used when it is not possible to obtain magnification by moving closer.
Hand held and ring style telescopes are used for distance spotting.
![Page 54: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/54.jpg)
For near and intermediate tasks, one can focus the telescope for near viewing by
a)adding plus lenses behind the optics of telescope
b)adding plus lenses infront of objective lenses
c)increasing the tube length of telescope.
![Page 55: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/55.jpg)
Reduction in the field of vision Ring scotomas Parallax and a decrease in the depth of
focus Not useful for ordinary distance viewing as
illumination decreases. These are consider contravesial for driving
because of constricted fields.
![Page 56: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/56.jpg)
Closed circuit television Large print computers Low vision enhancement system
![Page 58: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/58.jpg)
In this camera picks up the reading material,magnifies it and displays it on the TV screen.
CCTV magnifiers provide excellent contrast and magnification(linear magnification electronically upto 60x).
![Page 59: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/59.jpg)
It provides a distortion free, brighter, magnified image with enhanced contrast on a larger screen.
White letters on a black field helps in improvement of image clarity
![Page 60: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/60.jpg)
Expensive Heavy Difficult to move around May be difficult for some patients to operate
it.
![Page 61: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/61.jpg)
Computer can provide enlarged print on the screen through standardized or dedicated software.
Software is also available to provide speech for the computer.
![Page 63: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/63.jpg)
Recent advances in low vision rehabilitation
It comprises surgical implantation of intraoccular telescopic aids.
Intraoccular low vision aids consists of special lense that provides a 3x magnification in the fundus of patients eye.
Resultant retinal image is perceived through peripheral retina.
![Page 64: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/64.jpg)
![Page 65: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/65.jpg)
![Page 66: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/66.jpg)
Absorptive lenses- used to reduce the glare and dark adaptation time.
Especially used in patients with albinism.Types- Tinted lenses -Photochromatic lenses -Polarization -Filters
![Page 67: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/67.jpg)
![Page 68: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/68.jpg)
![Page 69: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/69.jpg)
![Page 70: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/70.jpg)
Field expanders used in patients with defects in
peripheral visual fieldsTypes- Fresnel prisms -Gottlieb field expanders -Reverse telescopes -Hemianopic mirrors
![Page 71: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/71.jpg)
![Page 72: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/72.jpg)
![Page 73: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/73.jpg)
![Page 74: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/74.jpg)
![Page 75: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/75.jpg)
![Page 76: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/76.jpg)
Approach magnification Lighting Contrast enhancement Increasing the size of the object to be
viewed Personal items Auditory aids
![Page 77: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/77.jpg)
![Page 78: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/78.jpg)
![Page 79: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/79.jpg)
Electronic devices Writing and communication devices Medical assistive devices Mobility assistive devices Tactile substitute include
Braille,paperlessBraille outputs and non-Braille tactile outputs.
![Page 80: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/80.jpg)
![Page 81: Low vision aid](https://reader033.fdocuments.net/reader033/viewer/2022061510/587ab7a71a28abc0478b4bcd/html5/thumbnails/81.jpg)
Orientation and mobility training Independent living skills training Support groups Braille instruction Computer training Genetic counseling