Vision Rehabilitation at The Indiana Eye Clinic

(formerly known as Low Vision)

The Big Picture

• To provide low vision devices and training for patients in need (magnifiers, CCTV’s, etc.)

• To educate them about and direct them to other resources for vision rehabilitation.

Patient Flow

• Patient recommended by M.D. or O.D. for vision rehab. (VR) because of reduced acuity, visual field loss or poor contrast sensitivity.

• Patient given info sheet by scribe or head tech that explains scheduling, fees, etc.

• Acuity 20/60 or better in better eye? Level 1 - regular schedule at GW or PF.

• Acuity 20/70 or worse in better eye or VF defect?

Level 2 – Thurs. AM in GW.

Flow continued:

• Technician: VR workup (more later)• Dr. F:

– expands history, refracts, counsels, educates, makes material recommendations and may discuss other resources available.

– Optical: Demo/educate materials

• Patients purchase desired items. • Some patients referred to

Crossroads/Bosma/IRCIL.

Fun Fact #1

Number of people in the “middle class” in the world today:

500,000,000

Coding for Vision Rehab.

• Refraction fees: • $20-65.00 based on complexity. • E&M codes:

– In VR, based on time the doctor spends with the patient (not including the refraction time) if at least ½ of the time was spent counseling and educating the patient.

• Level 1 - E&M code based on time:– If documented visual field defect – Amsler Grid– Eye/E&M codes if medical eval.

Coding continued:

• Level 2: – Refraction usually $30.00 -$65.00– Because of acuity level or vf defect, can

automatically use time-based E&M.– Primary diagnoses: level of vision impairment– Secondary diagnoses: medical (amd, etc.)– Eye codes if medical eval.

Coding cont:

• Medicare: No coverage for VR devices.– Can cover VR services performed by

physical/occupational therapists.

• Patients can obtain funds for VR devices from organizations like IRCIL (Indianapolis Resource Center for Independent Living)

Fun Fact #2

Percentage of Americans who say they would have cosmetic surgery if they could afford it:

69

Work-up: history

• Record medical eye status:-e.g., advanced dry amd O.U.,

homon. hemi, etc. as in normal work-up.

History Cont:

– Record visual symptoms:

Allow patient to elaborate on specific difficulties

e.g., “I can’t see to dial a telephone, pay my bills, read a book, identify a person, see the bird feeder, deal with glare, etc.

History Cont.

• Ask about desired visual activities:– “what would you like to be able to do?”

Reading, cooking, watching T.V., etc.

– Explore interest in rehab services:• Do you want in-home ADL training?

» Orientation and Mobility training?» Assistive technology

Fun Fact # 3

Percentage of British elementary-school students who think Issac Newton discovered fire:

60

Magnification basics

• Three ways to achieve magnification:1) Relative size magnification (making the object bigger) – CCTV’s, large print books, etc.

2) Relative distance magnification – moving the object closer to make its image on the retina larger.

3) Angular magnification – Magnification produced by an optical system that’s not from relative size or distance) e.g., telescopes.

Relative Distance Magnification• Bringing an object twice as close makes its retinal image twice as

large, so that results in “2X relative distance magnification” and so on.

• At near, mag compared to object at 25 cm.• Formula: diopters/4 = mag at near. e.g., 12D lens provide 3X mag.• Plus lenses – allow closer working distance without accom.• High powered and microscopic spectacles:

– 4-48D plus powered lenses• 4D lens – 25 cm working distance (1X mag)• 10D lens – 10 cm working distance (2.5X mag)• 16D lens – 6.25 cm working distance (4X mag)• 20D lens – 5 cm working distance (5X mag)

• Up to 10-12D, base-in prism for binocularity ?how much prism?: 4D add = 6 base in each eye

6D add = 8 base in each eye, etc

Hand/Stand Magnifiers

• Conceptually same as taking a microscopic spectacle lens and moving it farther away while keeping object at focal length of lens.

• As magnifier moves farther away, RDM decreases, angular mag increases but total remains unchanged.

• Same mag formula (power/4 = mag). A 3X magnifier is a 12D lens.

Hand/Stand Continued:

• Light from hand magnifier emerges parallel (as if at distance), so view through distance part of glasses (if object held at focal length).

• Light from stand magnifiers is divergent, so view with add.

Field of View

• Field of view is widest with microscopic spectacles, as lens moves farther away – field decreases.

• As power increases, field of view decreases.

For increased working distance:

• Use a telemicroscope. A distance telescope with a “reading cap” to allow focus at a closer distance.

• Formula:– Pt. with 20/400 vision wants to read at 25cm.

• 400 x 25/2000 = angular mag needed; use 4D cap for 25 cm working distance. Thus 5X telescope with 4D reading cap.

For far distances (angular mag):

• Reverse acuity fraction to get mag needed for 1M acuity.– 20/400 = 400/20 = 20X

Fun Fact #4

Number of U.S. states in which it is legal for first cousins to marry:

19

So what does M mean ?

• 1M-size letters held at 1 meter (1/1M) form an image on the retina that’s the same size as 20/20 size letters at 20 feet (5 minutes of arc).

• 1M print is half as big as 2M print, etc.• Phone book = 1M, newspaper = 1.2M, large print = 3m.• A patient reading 4M at a certain distance would need 4x

magnification to read 1M at that distance.• The M fractions are equivalent to Snellen fractions, e.g.

20/200 = 1/10M = 2/20M = .25/2.5M and so on.• Record the test distance in meters over the M size print

read (the ETDRS chart is usually at 2 meters but can be anywhere); the near card distance is often 25cm = 0.25 meters) .

Advantages of “M” for Vision Rehab:

• Since 2M is twice as large as 1M print, etc, easier to conceptualize than using Snellen fractions (20/70 vs. 20/20)

• More elegant acuity measurements at near (.25/4M is “better” than “reads 20/20 line at 40 cm”).

• Acuity describes mag needed at that distance for 1M vision:– Distance acuity of 1/12M needs 12x– Near acuity of .25/3 needs 3x (with 12D lens or 3x

magnifier).

How to calculate the add:

• To determine the power needed to read 1M print at near, use Kestenbaum’s formula:

• If the acuity is 20/240 (which equals 1/12M), flip the fraction and divide: 240/20 = 12. – A 12D lens in the spectacle plane would allow the

user to hold the material at 8.33 cm, which is 12 times closer than the material at one meter (12X) or 3 times closer than the material at 25 cm.

– Or, use a 12/4 = 3x magnifier and hold the material farther away, as long as the magnifier is 8.33 cm from the print.

– Or, use a 3x telemicroscope with a 4D reading cap.

Simplified Formulas

• Mag at distance for 1M vision: flip the ratio and divide. 20/240 (1/12) becomes 240/20 = 12X mag needed for distance.

• Mag at near for 1M vision using dist. mag: divide distance mag by 4. 12/4 = 3X.

• Mag at near for 1M vision using near va:– Flip near va and multiply by .25.

near va .4/4.8 becomes 4.8/.4 times .25 = 3X

A summary

• Measure the distance acuity at 2 meters using the ETDRS chart. Record it as 2/the M line read, e.g., 2/12M (which equals 20/120).

• Measure the near acuity by having the patient hold the print at the clearest distance. If the patient reads 1.5M at 25cm, record it as .25/1.5M (that also equals 20/120).

Fun Fact #5

Earthworms travel in herds.

So what materials do we provide?

• Stronger than usual (3-4D add) single vision reading glasses (usually level 1)

• Much stronger reading glasses (+4 to +48D) reading glasses (lower powers with base-in prism for binocularity)

• Small and large CCTV’s (the Pebble, Onyx)• Hand-held, clip-on monocular and binocular telescopes.• Illuminated hand-held and stand magnifiers• Filter options.• An assortment of near magnifier styles.• High-intensity reading lamps.

And beyond?

• Patients can be referred to:– Bosma Enterprises (ADL, O&M, Assistive tech., office

and in-home)– Indianapolis Resource Center for Independent Living

(IRCIL) – ADL , office and in-home)– Crossroads (ADL, office and in-home)– Vocational rehab

Activities of daily living, orientation and mobility training, other forms of visual rehab – covered by Medicare if provided by OT or PT.