section B4

LVA and other optical appliances

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  • Created by: Lauren
  • Created on: 29-05-09 14:48

LVA- handheld

Huge variety of hand held mags. Up to 10-12x.

Lens form's; Simple loupe magnifier (spherical or aspheric.)

How to use; Move the magnifier away from the object viewed until the image is found. (usually a little closer than the focal length of the lens). Keep this distance constant, the eye may then be moved closer to the mag to improve the FOV though this decreases mag slightly. Can be used with eccentric viewing.

Working Distance; 3x 12.5cm, 6x 4cm

Possible eye conditions; AMD, early cataracts, diabetes, old age

Impact aid has on everyday tasks; #easy to use #good for bank statements, bill reading, any spot reading activity, telephone directory. #cosmetically acceptable for self conscious patients.

Specific beneftits; Dynamic system so reading and distance or no specs can be used! *Px with distance Rx will hold closer to focal point of lens. Further from page! *Px with reading Rx will hold it closer to page than focal point of the lens. So very versatile in use.

Lighting and contrast; very important, white on black best! Iluminated mags available, concentrated light on object extremely helpful.

Not good for shaky hands trmor arthritic

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Stand mounted Mag

Lens form; higher powers are aspheric. above 4x for fixed focus and 10x for variable focus. And spherical for lower powers unless larger diameter then aspheric. Simple loupe mag.

How to use; On a flat surface, closer to the eye the more FOV that is obtained. Use with distance or reading specs depending on the power of mag. Over 5x best used with eye close. Over 8x best with distance Rx.

Working distance; 3.7x about 12cm to 14.7x very short working distance.

Eye conditions; 6x for AMD, lower mag for cataracts.

Impact on everyday tasks; for those with certain conditions like tremor and arthritis, material is steady and always in focus. Some can be used with pen, illumination optional, high mag given. does what hand mags do but steadily, good for elderly.

advice on contrast and lighting; same as hand held mag. sit at window light comes in over shoulder.

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Head mounted (spec mounted.)

Galilean or (terrestial) telescope. Galilean consists of a positive and minus lens.

How to use; Bring print closer from far away.

Working distance; short working distance due to limited level of mag. Distance LVA's for distance tasks, near for near tasks.

Good for retinitis pigmentosa, AMD, glaucoma or dense cataracts.

Used for watching TV, checking bus numbers, shopping. Near vision aids used for long periods of close work as are hands free.

Have good illumination and correct working distance, work in window with light on work for near objects.

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Magnification Unit

Much bigger than galilean.

One high positive powered lens aspheric. Extra plus available with reading cap, so versatile. Or could have -ve cap for distance.

Use in same way as LVA units. Specific use only.

3, 5,or 7x mag available.


Good illumination and correct working distance essential.

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Distance LVA (specific tasks use)

Telescope unit. galilean or terrestial.

Distance frame fitting is essential. Closer to the eye gives wider FOV.

Dispensed to patients with retinitis pigmentosa, AMD etc..

Can use with eccentric viewing when patient has central field loss. just used as for the purpose designed. Ie TV distance etc..

Use with good illumination and working distance.

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Fresnel prism

Temporary help with muscle imbalance, someone had knock or fallen.

Reduces the VA by two lines on test chart.

If sudden diplopia acheived could be a tumor.

Relieves hemianopia if applied vertically to half the lens (stroke victim)

Available up to 30 dioptres.

Becomes dirty quickly. unattractive.

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Hyperocular (pair of lentics)

High powered positice lenses.

Usually monocular as reduced convergence.

Close working distance.

AMD patients.

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Safety Spectacles

Apply to EN 166/167

Covers the supply of safety spectacles and personal eye protection in europe.

Spectacles are kite marked.

Polycarbonate F that are ten times more impact resistant that plastic can be used.

Thermally toughened glass S, heated to 600 degrees C than rapidly cooled with jets of cold air to build tension in the lens.

CR39 B lowest impact grade.

You can adjust but not repair or reglaze.

All are tested and impact graded.

Copy of certification must be given to patient or kept in record at supply of specs.

Glass scratches less.

manufacturer grade N is Norville, class 1 is spectacles. Over specs marked with F cant be glazed.

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Coil distance unit

Compund lens system positive lens at front negative at back.

Distance 4m+, inter 40cm, NEar 20cm.

How to use is for correct working distance very much trial and error with this.

AMD diabetes, diabetic retinopathy type A.

Again good illumination essential.

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Gallery on some not all.

Monocular patients.

Order flat form, best sphere and in polycarbonate.

Best sphere=sph+1/2cyl

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Recumbent spectacles

Mirror displaces the image, for bedridden people.

Can turn upside down for people with osteoporosis.

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Reversible spectacles

Monocular patients Dv in one Nv in the other.

Reversible joints and nose pads.

Turn upside down.

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Surgeon's spectacles

Galilean telescopes

Can be moved to set PD, and distance required.

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Trigeminal specs

Trigeminal cranial nerve 5 loose sensitivity.

Cant feel things in eyes so protection is needed.

No EN standard.

Frame repaireres will fit them.

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Ptosis prop

Droopy upper eyelid, levator muscles not working.

So, this holds up the eyelid.

Frame repairers will fit them.

stainless steel or plated metal titanium will cost too much

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Lundhi loop

People with facial paralysis, like stroke Px's, keeps eye open top and bottom.

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flip up spectacles

tint or reading add

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Make up specs

For hypermetropes. Ordered as best sphere.

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Snooker spectacles

two types these are larger

Non-aspheric!! SV

No tint needed, just an MAR

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Squash specs

Silicone bumpers, to take impact.

Polycarbonate lenses v=30 airwear v=31

Trivex v=47

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Shooting spectacles

For target shooting.

Use dominant eye to shoot

Put occluder over other eye.

Yellow sodium tint improves contrast.

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Swimming goggles

Best sphere order

Or sph-cyl but more expensive as you have to glaze them, mostly unecessary.

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Ski goggles

mirrir tint to reflect rays

polycarbonate lenses

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