P3D Subject: P3D Re: Hugo de Wijs VM viewer, Re: Normal interocular spacing?

[abram klooswyk <abram.klooswyk@xxxxxx>]

(Continued from P3D Digest 3222, 02 Mar and P3D Digest 3228, 04 Mar
1999)

Under Koo Ferwerda's chairmanship some Dutch stereoscopists discussed 
in 1973/1974 the possibility to design a general purpose stereosystem 
from scratch. One of the prerequisites would be "automatic" precision 
perforation mounting of 35 mm chips. Therefore a standard infinity 
separation for mounted stereo slides should be chosen.
Reasoning was similar to the arguing set out in the postings I send
last week. Stereoscope lens separation should equal infinity separation,
so to suit a maximum number of people with a certain stereoscope, it is
best to choose a infinity separation of mounted slides which comes close
to the mean interpupillary distance of the population you aim at.
I tried to find figures in literature and wrote a paper for the first
(founding) I.S.U. Congress, held in Wageningen, the Netherlands 1975,
where the paper was presented to the Technical Working party.
(Later Koo Ferwerda has quoted some of it in his - still available -
book "The World of 3D")

I guess several hundreds of million people are wearing glasses, so 
statistics on interpupillaries _should_ be easy to find. 
I probably didn't look in the right place (no Internet then), but the 
only paper I could find which gave a reliable statistical break down 
of figures was by H.W. Hofstetter in a 1972 article in the Journal of 
the American Optometric Association (vol 43 pp 1151-1155).
These were figures on adult white (Caucasian) males in the U.S.A., 
mean interpupillary was 65 to 66 mm, 99.8 percent was between 55 and 75
mm, but 10 percent was either below 60 or over 70 mm.
Hofstetter also said that the female mean is some 2 to 3 mm less,
and that probable 2 percent of adult white US females had an 
interpupillary less than 55 mm, but he didn't give details.

George Themelis wrote (PHOTO-3D Digest 3221, 1 Mar 1999):
>How about races? Seems that the Japanese have smaller average interocular.

The _opposite_ is true.
In my 1975 paper I have quoted a 1969 article by Helen B. Pryor on 
measurements in children (Pediatrics vol 44 pp 973-977).
She found that American born Japanese of the age group 16 to 24 years
had a mean interpupillary 4 mm _greater_ than Caucasians of the same
sex and age group. 

Searching through PubMed (http://www.ncbi.nlm.nih.gov/PubMed)
I now have found a number of abstracts which confirm the larger 
interpupillaries of some non-white races. (The free internet abstract
library of the U.S. national library of medicine/ national institute 
of health is a great service to mankind)
I quote a few abstracts (in the section between ====).

============
>The results of our investigations show that Japanese have wider 
inter-outer canthal distance (IOCD) than Arabs and Caucasians, 
both of whom have similar IOCD. Arabs have wider inter-inner canthal 
distance (IICD) than Caucasians. African-Americans and Japanese have 
wider interpupillary distance (IPD) than Arabs.
(Osuobeni EP, al-Gharni SS, Optom Vis Sci 1994 Jan;71(1):33-7)

>(...) Chinese children in Hong Kong. Values for (...) interpupillary
distance were found to be larger than those for Caucasian, Black, 
or other Chinese groups.  
(Quant JR, Woo GC, Optom Vis Sci 1993 Aug;70(8):668-71)

>(...) In this study 100 black patients (71 female and 29 male) (...)
The mean interpupillary distance for this study was 63.7 +/- 3.7 mm
(Murphy WK, Laskin DM, Oral Surg Oral Med Oral Pathol 1990 Jun;
 69(6):676-80)

>Two hundred and seventy-eight Nigerian, singleton full term neonates 
were investigated for interpupillary and internipple distances and 
ear length. The values were compared with standards derived from an 
American population. The study showed that the Nigerian neonate is 
hyperteloric, has a short ear, more closely spaced nipples (...)
(Ejiwunmi AB, Okanlawon OA, Ojo OO, Ann Trop Paediatr 1984
Jun;4(2):103-6)

>Arab males have IPD on the average 2.0 mm wider than females.
(Osuobeni EP, al-Musa KA, Optom Vis Sci 1993 Dec;70(12):1027-30)
==============

The Japanese firm Olympus makes camera's and microscopes, but also
equipment for optometrists and ophthalmogists. In Wageningen I have 
mentioned that they had chosen the range of 50 to 80 mm 
interpupillary distance for there machinery, so with a mean of 65 mm.

Helen Pryor's article also said that, in white Californian children,
about 50 percent had reached 55 mm interpupillary distance at an age
of 10 years.

In 1975 my conclusion was that a global mean of about 65 mm seemed
likely, but that stereoscopes preferably should accommodate the 
range from 50 to 80 mm. 
That means a _usable_ lens diameter of 15 mm when using 65 mm 
lens separation.

Abram Klooswyk


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