Theses, Dissertations and Capstone Projects

(1)

Pacific University Pacific University

CommonKnowledge

College of Optometry Theses, Dissertations and Capstone Projects

5-1964

A study of the relationship between the size of the physiological

blindspot as plotted with the Davidsen-Wottring caecanometer

and visual acuity under reduced or minimal illumination

J H. Marklinger Pacific University D F. Taucher Pacific University Recommended Citation Recommended Citation

Marklinger, J H. and Taucher, D F., "A study of the relationship between the size of the physiological blindspot as plotted with the Davidsen-Wottring caecanometer and visual acuity under reduced or minimal illumination" (1964). College of Optometry. 251.

https://commons.pacificu.edu/opt/251

This Thesis is brought to you for free and open access by the Theses, Dissertations and Capstone Projects at CommonKnowledge. It has been accepted for inclusion in College of Optometry by an authorized administrator of CommonKnowledge. For more information, please contact [email protected].

(2)

A study of the relationship between the size of the physiological blindspot as

plotted with the Davidsen-Wottring caecanometer and visual acuity under

reduced or minimal illumination

Abstract

A study of the relationship between the size of the physiological blindspot as plotted with the Davidsen-Wottring caecanometer and visual acuity under reduced or minimal illumination

Degree Type Degree Type Thesis

Degree Name Degree Name

Master of Science in Vision Science Committee Chair Committee Chair D.T. Jans Subject Categories Subject Categories Optometry

(3)

Copyright and terms of use Copyright and terms of use

If you have downloaded this document directly from the web or from CommonKnowledge, see the “Rights” section on the previous page for the terms of use.

If you have received this document through an interlibrary loan/document delivery service, the If you have received this document through an interlibrary loan/document delivery service, the following terms of use apply:

following terms of use apply:

Copyright in this work is held by the author(s). You may download or print any portion of this document for personal use only, or for any use that is allowed by fair use (Title 17, §107 U.S.C.). Except for personal or fair use, you or your borrowing library may not reproduce, remix,

republish, post, transmit, or distribute this document, or any portion thereof, without the permission of the copyright owner. [Note: If this document is licensed under a Creative

Commons license (see “Rights” on the previous page) which allows broader usage rights, your use is governed by the terms of that license.]

Inquiries regarding further use of these materials should be addressed to: CommonKnowledge Rights, Pacific University Library, 2043 College Way, Forest Grove, OR 97116, (503) 352-7209. Email inquiries may be directed to:[email protected]

(4)

\.._ } l I ..__ I ,,-· ', ' ·--~···" ..

-A STUDY OF 7HE RELATIONSHIP EETVJEEt~ THE SIZE OF THE PI-1YS IOLOGICAL BLINDS POT AS PLOTTED t-IlTH THE DAVIDS

EN-HOTTRING

CAECANONETER

AND VISUAL ACUITY UNDER

REDUCED

OR

MINI~~L ILLL~INATION

CLINICAL YEAR PROJECT

By

J. H. Marklinger

D. F.

Taucher

Pacific University

May, 1964 -~

-

··

· ~

.

~---,

I ..--·---.. .

rf

· -~

1:.

(5)

J,:

.

' ' (

ACKNOHLEDGEMENTS

·He express our appreciation to

Dr.

D. T. Jans,

Professor of Optometry, and

Dr~

Hilliam R.

Baldwin,. Dean of the College

of

Optometry,

for

their

guida.nce and

interest in

our project.

Curtis,

and Eo Ragsdale, both of whom began ~>7_0rk_on

_this

_proj:ect

_{in May}

_{19 63) our}_thanks for the contribution of their basic research a.nd

data

from

t"t·;enty

subjects

which

combined

with

our data has

made

the

population for this project more significant.

We

also wish to thank

the

Diagnositic

Instruments Company of Muskogee, Oklahomq

for

making th(.; Caecano-meter instrument available to us and for

suggesting

this project .. In addition "ve wish to

thank

those who

so

\,>Iillingly

cooperated vJith us by

serving

as subjects for this

studye

J • H. D. F • M

...

... l .•

(6)

,, __... ...

_

,_

_... _,~ji _.l.•. _.:..

CONTENTS

PAGE

PURPOSE" 1

INTRODUCTION:

REVIE"vJ OF LITERATURE 2

PROCEDUP .. E 7

ORGAl:HZATION OF THE DATA 8

DATA

9

DISCUSSION A~'iD CONCLUSION

16 CITED

17 NO

T CITED

18 .

.

(7)

-l

PURPOSE

..__

This project was undertaken at the suggestion of

the Diagl1ostic Instruments Company (DICO) of Huskogee,

Oklahomao

They were interested in determining if any

correlation exists between the size of the

physiologi-cal blindspot as plotted

by

the Davidsen-vJottring

Caecanometer Hodel 75, which they manufacture, and the

visual acuity of a patient under reduced or minimal

i 1 h.1mina tion o

In addition to the information

~vanted

by DICO

t-Je

added a second variable vJhich v.ras visual acuity under

reduced illumination after tw·enty minutes dark adaptationo

-,~

.

.,

.

/'· - - . - - - ... ,.~,,.,....__.--~- _..,T••• -...

(8)

2

INTRODUCTION AND REVIE'VJ OF LITEP ... ~\TURE

In order to investigate the possibility of any existing correlation betvJeen the size of the physio;,;,. logicel blindspot and the visual acuity of a patJ..ent

under

reduced illumination,

as

stated in the purpose

,of this project, it was decided that the data collected

by Curtis and Ragsdale \vould

be

added to -our ·, data

consisting of an

equal number

of

subjectso

This has enabled us to correlate the fi:ndings of forty subjects (eighty eyes). The data 1<vas collected in both cases in the same manner consistent 'i.vith that CY";V~"'11 .: • .., ·l-j-.p 11DrOCPG~,, •• e 11 O'c t'_;.l_i c.::

o-'- '--- ..1..1. ...,.~. .1: ~ -· '-·'· .:.. • ~ papero

A discussio:n of the history, development,

and-cli.nical significance of the Davicisen-Hottring Ca.ecano-metE:,l: ~vill serve as !:om introduction to this project. Dr o L OQ Davidsen, o11.e of the designers of the

instru--ment, has giyen his views on wb.at prompted inv-sst::Lgations

of th1.;; blindspot and development of the caecanometer. Ideally, patients desire to see clearly and

com-fj)rtably~ l,o1<·1ered visual perception of an elusive

na-ture, ~-Jhich impaired vision from unfam:Lli.ar causes, distressed L Oo Davidsen very much.. He noticed these patients with 1_1J.owercd_{visual pE:rformance}

!'

_tn_o~e_{o ten}

than could be explained by mere coincidence., to be the same patients Imo;;m to be suffering from mild

patho-l

ogic.a._

conqitions o

---

--\.~ - - -- r -...

(9)

_

...

.-.:. .. ~•-... -- . -

.

' . • - -.-... -~,-·.i.:.. .... "'_;•-...:....,;;c..-~ ... ;. . ,; ... >.~---' .. ',<_ -;._.)'-;. • .,:;,.:t .. -..,J.., • .-... ·:~.·~~~\. ii.<o..oi~c".-.!;;..,.~lf(:a,.j~.~ ... "

3

Thn~e

areas of

study

v-rere

L1erefore

ini

tiated

.,

I

·~

The

first to be

studied

in a search

for

methods

of

cor--

-r

elat

ing

k.:.1.mvn

pathological conditions

~vith

retinal

respo21se

v1as

the

macula, 'tvhich is

knmv·n to

be

the

most

sensitive

area.

of

reception.

This

holds

true

if the

ret-ina is in a light

adapted

eye, the reverse situation

is seen in

the

dark adapted eyeo

The

fovea exhibits

a relative scotoma in low illumi:nationso

Highly

sensi-tive and

controlled

fi

eld

plotting tecru.

1ique

wer

e used

for the macula, but did not present

the

ans

wer

i

n

co

ns

istent recognizable

s~gns$ •

The .ne::.<t ~.rork was directed to

the detailed

study of

peripheral fields and again no significant

correlat

ion

betv.reen known pathological conditions and

c~rtain

typical

(

\

signs i.n

the

peripheral

fields

'ivas

foundo

The

third area

of study ~las the

optic

ner\re

head.

A

relatively consis

tO.fit

size and position has

been

es-tablished

for

the

nerve

head

o

It t,.·.;as

realized th

at

known

pathological i

nv

olvements such

as

oral,

sinus~

and

throat

infec

tions

ras

u

lt·

in

an

increase

in

the

plotted

size

and

shape

of

the

nerve

head.

Th

stati.st_c~

· outc

ome

of

the

study after treatment

for

pathological

condi

tions

did

not

indicate changes in the blindspot

a!.ea

as

often

as

.

\·Jas expected.

From

these

'

clinical

de.ta

discrepancies

DJ::'.

Davidse1it

s

curiosity 'Vvas aroused

to

the extent

that

he

altered

t

h

e

technique

of measuring the blindspot

.

(10)

-pt:!o:- ... _ ... '

4

He set out to find a ·method to obtain repeatable

and more de}!•?ndable chartings. The big surprise came

\V'hen the target 't·Jas moved from the seen to the unseen.

It ~vas found that typical changes vJere taking place

in the ner-ve head size and shape when the lmotv-n

patho-logical conditions \vere eliminatedo By using the te

ch-nique of moving the target from seen to u.nseen, a zone

of indecision of t\vo to three millimeters -r, .. ;ras reduced

to an average of only one-half millimeter. Best results

were obtaihed by moving the target at a steady rate of

speed, appro:dmat-ely eight millimeters every three seconds o

TtNO m.ore problems

"vere

encotmtered -vv-hich

influ-enced the reliability of the blindspot plottingo The

first vJas the distance the fixation target is placed

....

( y

from

the

oatiento

A

distance

of

ten to thirteen inches

';vas used in an attempt to determine the best distance.

Also, an ezact fixation target: \vas a must o

The se.cond oroblem 'Iivas that the usual vJand aroused

entirely too much peripheral rivalry causing mental··

visual confusion. To eliminate the h.:inclle of the \·land

a set-up "t-.ras designed so that a magnet would guide the

target from beneath the chart so that orily the target

vJoulcl be obselv(~d ~

This vJas the beginning of

a

new technique of meas

-. -. -. . ' · . . , . 1 1 1 ' . t ' " ' 1 ' 1.

ur~n;; -cne pnys~oJ.ogJ.ca o_J.ndspo :rrom t"·1e seen to t11e

unseen· 8~nd a :ne;;v instrument having a minute foveal

fixa-.. t:-ion ·target and a small remotely controlled test object

(11)

'· } 'i~Nirr---o ... l~-... ' I" •~-... :..~ .... c"-"'>---.:..- ... ,, .. ,_... •• ..._.,_, _,._,.,_,.. _ _.._ ... .,. ... ... .. . ..;fj • ..;.!} 5

at eight inches from the eye. The instrument -vms named the cnecanometer from the Greek \vo:;::-ds "caecus 11

meaning blind and "me try" \.Yhich means to measure.

By

researching three-thousand. patients under pro-fessional care

he

concluded the: follovJing: .

"1) The area '!;vithin the blindspot does, in the pres-ense

of

certain types of infection, ShO.\'J' a COnstriction in the plotted size as compared to the normal or ex-pected average area; 2) that such restric~ted area always regains its

mm

normal size ~vhen the source of

·infectim1s has been eliminated; 3) that a res trlction of the blindspot: almost invariably accompanies cases of drainage types of infections above the shoulders. i:l

Research has confirmed the value of this new tech-

_.·

nique. Dental patients under the control of oral

sur-geons TOve e charted before and after surgery and the

t.ypical changes in size and shape of the blindspot v-lere noted

c2

Optometric patients

~vhose

discomfort had not been amendable to standard optometric procedure vJere

referr(~d to and treated by Ophthalmologists, and ear,

:nos .~ mid throat specialists o AfteJ: treatment,

blind-spots sho;;ved. an increase

in

size and visual

involve-.,.,

ments \vere reduced. :J

Clinical significance of data obtained from re-search involving caecanornetry is varied. Syrnptomatol-ogy res1...1lting from infections have been successfully treated due to caecanometry detection, such as complaints of photophobia, accommodation and convergence function

(12)

6

di9comfort during examination, lmvered night-sight

light levels, contrasts of visual acuity, i.e., tvith

f

20/20 vision yet complaining, "I do ~not see clearly11_,

unequal acuity of the t';vO eyes·, altered depth perception,

and combinations of the above complaints.

J.vrany practitioners in the visual care field have

attached great significance to the caecanometer and its

value in the detection and diagnosis of glaucoma. Th.e

.Standard Technique of plotting from unseen to see is

used in glaucoma

studi

es

~

b, .

....

--

...

:.~

~I ,: ,,

(13)

' ~_F_~_"-.-

-7

PROCEDURE

A. Plotting

of the physiological blindspoto

The

physiological

blindspot of each

eye

of each

patient r;,.,ras plotted

using the

techniques outlined

in

the Ivianual of

Operation of

the Davidsen-Wottring

Caecanome

ter

~1ode 1 7 5.

1.

The instrument was

set at

medilli~

illumination

level.

2o

Plotting was from seen to

unseen in

the

ver-tical and horizontal meridians.

I

3.

A

LS

mm target

vJas

used.

4. Target

~ms

moved at Smm

per

3 seconds.

B.

Visual Acuity

Under

Minimal Illuminatiori.

I

.

The

subject

was

seated with subjective

refrac-tion

for

best visual acuity in

p

lace.

2. The room was darkened

completely f

or

thirty

seconds.

3. One eye

was occluded.

l~.

The

Powerstat Type

116

was

''Jired into the

elect-ric circuit to

the projector

so voltage

could

be

gradually

i

n

creased

until the subject

could

recognize at least four

out

of

si~

20 /20 acuity

letters

(TZVECL)o

5.

The voltage

required

tvas obtained

from

the

voltmeter scale

on

.

the Povverstat o

6. The

procedure

(1-5)

was

repeated for

the other

E.~ye

•

7o

The

ab

ove

procedure

(1-6)\vas

r

ep

eated

on the

subject

after

t\v

e

nty minutes dar

k ad

aptationo

Inst

rument L

i

st:

Hodel

7~ Davidsen-~,Jottring

Caecanometer

American

Optical Proj

ector

American

Optical

Rx Master

Refract

ion Room #24

Optometric

Clinic

.

V:L

sua

l Fields Lab Optometric

Cli

n

i

c

Pacific

University

Pm-;erstat

Type

116 0-140

Volt

Ra

n

ge

l.Snm1

Steel Ball Bearing Targets

..--...1 f""";

--r···-~--~---·-··-;---~···----.. -('1'1. h' ... ,...,_...,~ ---~~~-- ---~r

...

· ..,.

.

.,.,., .. ,..,.,.,..,.,

_

__

~

..

:

.

,__

__

____

___

____

__

r·-.

(14)

8

ORGANIZATION

OF

THE DATA

Forty subjects

with

an a

g

e range from ten to

fort

y

-seve

n

years were

testedo A

distribution by

age

and sex is as

follows:

L~:..r;e

Subjects

::S·e;{

1o~zo

10

7

F

3 H

20-30

22

4

F

1

8

~~I

30-lt-O 5 2

F

3

1Yr

l~l-47

3 ,

.J.. F 2 !1

l~O

14

F 26 H

Of

th

ese

, 20%

we

re

non-college

stud

en

ts,

60%

were

col-l

eg

e students, and

20/~

were in various occupations.

Fifty

percent:

\vere myopes,

37.5%

-r.

v

en: hyperopes

and

12 .5/o '(,ve~:e

emm

etrop

e

s.

(

Tabl

e

.ffl

lists percent of

reduction in

blindspot

'---a~e

,

volt~ge

for

20/20

acuity

after t

h

irty

s~conds

I

dark

ada

ptati

on and voltage for 20/20

acuity after

t\'1enty minutes

.

dark

ada

ptation.

Figure

No

.

1

is

a :scat

t

e

r

g

ra

m

· repr

esen

ting

the

volt-age

:required

for the

subject

to

'

attain

20/20

acuity after

thirty seconds dark adaptation in relation

to

the

siz

e

of

the biindspot

in

P'~rcent

reduction in·

area

.

Figure

No

.

2 is

a scattergram

repres

en

ting

the

voltage required

for

the subjec

t

to

atta

in

20/20

acuity after t

v;

enty

minut

e

s dark

adaptation

in

relation

to

the siz

e

of

the b

li

ndspo

t in

percent reduction

i

n area

.

The formulae

used

in

.

the statistical

ar~alysis

· are

..

giveil

on

pagel

4 and

th6

statistical

results

on pagesl4-15.

...

_''

_ ... --~..,.. .• , ,.-~ ....

F-~,---~-.-··---1'!!:~-~m, ·~....---· _I

...[-,._

_l_•--.o _. ' I

(15)

9 -DATA

Table

I

Voltage Required

F

o

r

20/20

Acuity

Percent Reduction After

30 Seconds

After

20 Ninutes

Subject

In

Blinds pot

Area

Dark Adaptation

Dark

Adaptation

1.

20/~

42

28~~

38

42

2.

., ':lO'! ..)_t 10

43

42

16/~

45

45 3o

l?CJ

_-lo

₅₅

₄₃

221~

52

40 4.,

12%

36

35

00/~

35

c: _28/c

_4-1

₃₉

_,.

25/o

4-0

35 6s

18%

L~7

4i

, "'(Jf .I..L lo L,6

41

7. 20%

L~tt

₄₁

28%

4-2

40

I l

_8.

"'I"\ at _.LL_/o

₃₈

₃₃

4L~%

₃₄

₃₁

9.

00/o

43

45

08/o

41

45 lOo

28%

lj.Q

₃₉

28%

t~o

4-1

llo

08%

4-3

41 08%

46 4-2

12o

20%

L~O

39

16/o

38

40

1

3 .

40%

46

44 .

56/o

43

L~2

14o

16%

40

37 04%

38

37

15.

18/o

41

39 00%

{;.2

₄₀

--·

1."'-- -• • -·---r.-~-~

-

~--~

(16)

16. 17 ..

18.

19.

20.

21.

22. 23o

24o

(_

·

25.

'

26.

27 ..

28 .

29 ..

30.

31. 32o

---;--r-....--+;"----~ f· ~""", ~ L₁.• 12~~ Ol,"i -r /o

00/'o

00%

08/'o

08%

00%

00/o

20%

6,8%

12~

00%

04~~

08/'o

25/o

12io

12%

16/o

06%

18% 08/~ 20%

04'/o

16%

63%

33/o

08.(~

04%

40%

24%

30.<11 7/t: l;.1{4>

29%

51

L~2

55 so

40

L,6

41

L.cS

so

40

44

43

41

39

65

55 4-5

47

37

35

L1-l

38

42

L!-3

so

58

43

45

L~6

47

38

33

10

so

4-5 55

46

50

49

42

L:-2

36

39

35

39

33

34

55

54

4

0

4.

0

33

3:5

41

38

39

38

45

44

48

46

47

36

38 ,_- :...--.--.. ~---..,...---..,....,-.~1 L - -- ---- -.:..--- - - ...,1

(17)

- l, --~~- ~~ -Ia-.~ - ~1-M.i.ooii- _..IJI ftUi-t-..._.,__..._:r-~

:n

33.

6

_..),o'>"";'

39

33

'

_24/o

₃₇

32

--~:./

34.

[, ~"'!

₄₅

45

• - tO

45%

55

35

0

57%

33

33 68'7o

33

36 .

L:-0%

37

41 24'7o

49

47

37. 3.6."''

• /o

40

32 24%

40

31 .38

..

? Lt."'"! - '10 l~6

43 31%

55

50

39 .

20'7o

35

34 20%

36

33

I '

₄₀

_.

_29%

4-1

L~o

20%

43

L~1

(__

f~.

.

-.-... '___,.,...,...---··--~-···---,.,..,._...,...,.t

(18)

v.

(

"-~· qj (j) H ·<C ~..) 0

12 Figure 1 is a scattergram representing the

voltage

required f<W the subject to

attain

20/20

acuity

after

30 seconds

dark adaptation in relation

to

the size of

blindspot

in

percent

reductiori

of

areao

66-681

X

64-66

62-M- X

60-62

X

58-60

g.

56-5

8

'"d _5l>-56 v

_"'

~ ""· A ·.-1

52-54

-,-.4 50-52 i:Q 1..1-l

48-501

0

46-r+sl

X

s:: 4

.

4-4

-

6.

X 0

_42-44

_X _X ·.-1 40-!+2 _X .j..l C)

38-40

v X X X X ;J L\. '"d

_36-38

())

34-36

~ .j..l

32-34

X X X ...

_30-32

_v , ... (\.1 .!'!... C)

28-30

_X X H

_26-28

X XX X X (j) P..

_24-2

₆

_X

22-241

F X X y ~ 1~

20-22

ZK X X

18-20

v

XX

.

X X X v " .:\. 1'1. A

16-1

3

X

14-16

X.t'C X .l'!.. v X

_"'

1\.

12-1

4

1 10-12 v

_XX

_X

""

X y L• X

8-10

v ·~

6-

8 X X X X J'>.

_"'

X X

4-

6 X

2-

f.J.. _~-.._'" v 1\. _"A _"h. v L'l. o~ .,.,(. . j _X _X ;.(~{ _i\._'" X '" _!\.. X ~23334Js36373s394o414243444546474s4ssos1s2s354ss

Voltage

Re

quired

For

20/20

-Fig.

1

*----.

~=

.

!'"9 -~~:-:-:-~ ... -~~.-~-... --~---._:._-,----,.--....:..:!,.- --·~

(19)

~ ... I_

~· I I I I • ' ·

-~ ,~

...

--....

...

--Figure 2 is a scattergram representing

the voltage

required

for the subject to

attain

20/20

acuity after

20

mim1tes dark

adaptation in

relation

to

the

size of

blindspot

in

percent

reduction

of

areao

66-8

.

_••

v

64-6

62-4

X X

60-2

58-0

56-8

X

54-

'-"·

I

"

X Cil 1\. <l) 52-C~: i-1 <C

_50-2

.p

48-0

0

_L}6-8

_X p.. rJJ

44-6 {

'"d

42-4

XX ~ ·r-1

_40-2

1 v r-l 1\. t-1:1

_38-0

_X v X 1\. 4-1

36-8

(

_

0 3L1--6 ~

_32-4-

_X

_X _X 0

30-2

·r-1 .w

_28-0

v v 0 1•

""

::!

_26-

_G

_XX

_X ~Cl 2L:.-6 X X X I!) t:~

_22-4

,~ X X X ·~ -IJ

_20-2

v _{;{ v}

c.

~~ L\..

18-0

X X v _X _X IJ) A ()

16-8

··v· X X X ~'-i

_"

_'"

(j)

_14--6

.. ,_, .. v v v

,,.

~4 i\..

"

i\. 1\. .{\.

12-4

10-2

X v X '.7 _X _X X · 1.~ 1\.

-8-~D X X 6-·8 X X v _{. .1\.} _i\.v _X _{X X}

4-6

X 2-~~ v _X _X _X _'\.

"'

0-2 :1' .X }~X X ~X X }~ 313233343535~738304041424344454647484950515253545556575859606152636465

Voltage

Required

For 20/20

(20)

(

_

(

,

___

- r

.~ ...

STATISTICAL

ANA~YSIS:

Formula

e

Hean

(X

and

Y

)

X

=

X/n

where

X=

voltage for 20/20 visual acuity

.

Y

=

minus percentage reduction

of

blind-spot

area

n

=

numbe

r

of

values

= 51..1rn

Sta

n

dard

Deviation (s)

s

=

v'lx

L

/n-

1 (X values)

s

=Vly

2

/

n

-l

(Y

values)

i'Jb.ere

y =

Y ,...,

Y

Va,.J· "''1C<=>. I<" 2) ... ... ,_ .. o.~ ~. ··\ p ' ,.. "

s

L=

t.

xL

/n-1

(Y

valu

es)

Cor

re

lation Coefficient (r)

r

=

[.

xy/n-

J/'(_l..

· x'l}J

n-1)

(r_y2

/

n

-1)

Test for

significance

(t)

t

=(r/Vl-(r

2

;)Vn-2

St

a

tistical

Results

Re

sults

after

30 seconds dark

ada

pta

ti

on

s s

(X

.

values)

~

43.025 (Y

va

lues) =-21.600

(X

values)

=

(Y

va

lues)

=

16.11

6.12

s2 (X

v

a

lues) -

37.47

s2 (Y

values)

=259o69

r

correlation

of X and Y

=+

& 39

7

t

test

for

signific

a

nce

=

3.84 ..

-~-·-c-~--··--~··- _f.!li' _{_}

•

(21)

\,_

I

L

Results

af~er 20 ~inutes

dark adaptation

x

v

s s

(X values

(Y

values

(X v;::lues (Y values (v A

(

,. f..

values

'-lal.ues \ =

) =

-21.6000 L~Oo7625 ~ i f -' • l I 16.08

33.22

258.4.2

r

correlation

of X

and

Y

=+0.24

t

e

st

for significance

=

3.60 ----.

,

~~~·---~~

---15

(22)

-.

, ... •( \__._ { \_ -- -' ...L. ~ ..J'~. • .;-f. ~ :-I. >I ,.;

.-:--DISCUSSION AND CONCLUSION

This study

was

conducted

on

the pr€:mise that

sub-jects \-Jith reduced blindspot areas vJould

require

a

higher minimal voltage

t

o

read 20/20 acuity letters

than

subjects

\-lith normal blindspots

o

Based on the sampling of forty patients (eighty

eyes),

the

data, the scattergrams, and

the

statistical

correlations indicate

low

association

of

t

h

e

variables

~ompared

in this proj.ect.

The

correlation

coefficients,

+Oo397

for the thirty

second

dark

adaptation

'

, and

+Oo240

for the tv·7enty

min-ute

dark

adaptation

,

are not great enough to indicate

a definite relationship

of the reduc

.

ed blindspot areas

to the amount of voltage required to read 20/20 acuity

letters.,

Ou

r sampling contains

a

good

variation

of

type

s

of

individuals

but the data i:ndicates

variabtlit

y of

voltage requirements as compared to equally constricted

blindspotso

I

n

view

of the values obtained for the standard

deviation;p) correlation coefficients,

and

t

es

t

s of

sig-nificance,

~~

feel that the premise on

~vhich

this

pro-ject

v:as

conducted

is clinically

non-usab

l

o

(23)

I \

17

REFERENCES CITED

1. I. Oo Davidsen, O.D., "The Evolution of a Ne'Vv

Tech.~.'1.ique", Journal of the A. 0. A., Vo1,

34,

No.9,

PP•

701,

April,

1963.

2. Ccuy Fenton, O.D., 11_{Blindspot Restrictions",} _Optometric

liJeekly, January

7

and November

4,

1954.

3 o

L

o.

Davidsen, O.D., "Blindspot Constrictions",

Optometric vleekly, PP•

1197,

August

4, 1949.

4 -

o

Lin Hoore, O.D. and John Bradley, 0. D., "The Sinister

Halo", Optometric ~veekly, pp.

_2405,

Decem)Jer 6,

1962o

5o Allen Lo Edi.,7ards, "Statistical Analysisn, Rinehart &

Company, Inc., New York

1959,

pp.

40-53-68-167.

6o

Curtis A. Lo, ai1d Ragsdale, E. K., ''A Study of the

Relationship Bet\·Jeen the Size of the Physiological

Blinds pot as Plotted \,vith the Davids en-~vottring

Caecanometer and Visual Acuity Under Reduced or

~1inimal Illumination" o Clinical Project Pacific

University, January,

1964.

'•

(24)

(_

-...

-

,..,..

_

___

...

_

-REFERENCES NOT

CITED

lo Lin Hoare, O.D., "Caecanometry For Complete Diagnosis",

Optometric \veekly, September 22,

1955.

2. I. Oo Davidsen, 0. D., "Restrictions Of The Blinds pot

J,:;;:ea :·_nd Their Significance To Lmvered Visual

Achieve-rnent~~ ~ Optometric ~veekly, .August

1949.

Jo A. Shreve, O.D., "A Caecanometer Case Report", Optometric h'eekly, October

1955.

4o C. Eo Pheiffer, O.D.

''An

Analysis of Clinically _

Obtained Caecanometer Data", A.O.A. Journal, August

1959.

5. ~-~. J. Hirsch, O.D. and H. Schapero, O.D.,

"TheRe-lationship Betv1een the Size of the Blindspot and the Presence of General Infection11

, Aro.erican Academy of

Optometry Journal, :t-'Iay,

195lo

7.

J . H. __ Kensett, O.D., "Experiences in Chart in~ Blind-spot Restrictions11

, A.O.A. Journal, April,

1:163

G. A. Scott, O.D., "Instrumentation and Clinical

Testing for Caecanometry11_, _{A.O.A. Journal,} _Apri_l,

_1963.

r-_,-~--n:-... -,..._._.,._~,,---=---

.

~ ~i) '