You can try measuring visual contrast sensitivity function maybe.

Next-generation vision testing: the quick CSF

Michael Dorr1 / Manuel Wille1 / Tiberiu Viulet1 / Edward Sanchez2 / Peter J Bex2 / Zhong-Lin Lu2 / Luis Lesmes2

1Adaptive Sensory Technology GmbH, Maria-Goeppert-Str. 1, 23562 Lübeck, Germany

2Adaptive Sensory Technology, 225 Friend St, 02114 Boston, MA, USA

You can read the details http://www.degruyter.com/view/j/cdbme.2015.1.issue-1/cdbme-2015-0034/cdbme-2015-0034.xml ( open access)

Thank you!!!Looks like something very useful indeed but question lies over its repeatability and sensitivity as there do not seem to be enough works done to conclude the same. Do you have any literature in your knowledge in support?

http://iovs.arvojournals.org/article.aspx?articleid=2333807 

look for repeatability

It's possible that 'form from motion' perception would be affected. We have a task that measures ability to see shapes defined only by motion contrast that we have shown is sensitive to slight cerebral insult. (Paper in press) It should be published in next few weeks, if your interested I can forward you the link when it's up.

Thanks... Would love to read it!!!! Does this quantify the change in the perception as well and perhaps give some sort of estimate of quantitative measure of visual funtion for correlation.

I agree form perception might be a way to go. However, don't you think motion perception being a function of magnocellular pathway is less likely to be affected by changes in choroidal blood flow and perfusion though? Thoughts?

I'm not sure Safal, Magnocellular cells are more vulnerable to hypoxia that parvocellular cells. But this may not be relevant in the retina.  Motion perception requires input over many cells from a wide receptive field - so it may be a candidate.  Just guessing though.

Would love to go through the paper once it is available though!!!!

In the meantime look at these papers:

Visual processing of motion-defined form: selective failure in patients with parietotemporal lesions.

Regan D, Giaschi D, Sharpe JA, Hong XH.

J Neurosci. 1992 Jun;12(6):2198-210.

Motion-defined letter detection and recognition in patients with multiple sclerosis.

Giaschi D, Regan D, Kothe A, Hong XH, Sharpe JA.

Ann Neurol. 1992 Jun;31(6):621-8.

Hi Safal,

A function that has been shown to vary in a circadian rhythm is temporal resolution. A likely cause for that is retinal perfusion, which itself linked to blood pressure:

http://www.sciencedirect.com/science/article/pii/S0042698900001759

Unfortunately the described technique of double-pulse resolution is no longer available.

But more generally you might check for visual functions that show rhythmic change (there is, e.g., a book “The Retina and Circadian Rhythms”), because a likely cause is choroidal perfusion. That said, however, most visual functions show pronounced rhythmic change, with all kinds of rhythms. Even most basic functions, like acuity or contrast sensitivity do. This fact is just generally ignored because it gets in the way of visual diagnostics. As someone else already pointed out above, the key is reliability. Most psychophysical measurements are indeed highly reliable when measured with some efficient adaptive algorithm (like the quick CSF). Letter contrast sensitivity is particularly reliable (and has a steep psychometric function as shown by myself).

Check out my overview of visual measurement for that:

http://www.visionscience.com/documents/strasburger/strasburger.html

As a direct answer to your query, however: I do not know of any direct proof that it is choroidal perfusion which is the cause of all those visual-functional changes.

Best, Hans

Hi Hans,

Thanks for putting this together. We are investigating on methods of increasing choroidal perfusion and as such, we are on look for possible senstive tests (or customization of currently available ones) to see if there is indeed any improvement in visual function!!! But the exact problem lies in the sensitivity of these currently available tests to pick up those subtle changes which we are expecting!!!

Thats a great overview of visual measurement indeed!!! We are currently thinking of qCSF and FrACT and further customizing them to enable them to pick up those subtle changes!! We just feel these are out best bet at the moment but still exploring further!!!

Thanks again,

Safal

Sounds promising!

Basically, precision increases with the number of trials and the number of alternatives. I have always used 2 x 30 trials per measurement point in a 10-afc task. Standard deviation error bars were often not visible because they were smaller than the symbol size. 8-afc Landolt-C is preferable over 4 afc. Psychometric function slope is an indicator of precision; the steeper the better. Check out www.hans.strasburger.de/reprints/pp_invariance.pdf for the principles.

Hi Safal,

This article could be of your interest.

http://journals.lww.com/optvissci/Abstract/publishahead/Functional_Visual_Acuity_in_Age_Related_Macular.98630.aspx

Cheers!

This paper seems promising. Thanks!!!