Comments on: The Electroretinogram and Electro-oculogram: Clinical Applications

By: sahar

sahar — Thu, 09 May 2013 17:02:22 +0000

Hi,thank you very much for this article.could you send me a raw data of eog signal(with right and left movements)?
thank you

By: Donnell Creel

Donnell Creel — Fri, 12 Apr 2013 14:38:19 +0000

Pattern ERGs stimulate localized areas of the retina with patterns instead of a global flash, which makes them great for mapping local dysfunction in retina such as macular degeneration, enlarged blind spot, and mapping scotomas. However, pattern ERGs are not as informative when a “whole retina” disorder is involved such as retinitis pigmentosa or a cone-rod, or cone dystrophy.

By: Charles Pritchard

Charles Pritchard — Thu, 11 Apr 2013 14:23:47 +0000

Dear Dr. Creel,
how does Pattern Electroretinogram (perg) differ in testing than ERG test

By: Don Creel

Don Creel — Fri, 15 Mar 2013 03:08:56 +0000

Thank you for your support. If questions arise please email.

Don Creel

By: Pradez

Pradez — Thu, 14 Mar 2013 23:39:02 +0000

Dr. Creel.

I am a student studying and conducting research into sensory homogenised conditions such as the ganzfeld effects of sensory flooding and flicker light induced experiments using EEG. I have found this page particularly useful in building my knowledge and understanding of ERG and its clinical implications as well as relating the information provided here for my project to further theorise and hypothesise the top down and bottom up processing models of sensory input to the cortical areas of the striate, primary visual cortical layers such as the higher processing units (V1-V5 and LGN). Many thanks and Best wishes!

By: Michelle

Michelle — Tue, 26 Feb 2013 08:53:34 +0000

Thank you for your answer. The acuity was tested and it eas 20/200-20/300 not corrected (myopia of -3). My hope is that glasses can improve that to some extent. Have you ever seen improvement in photopic responses on the ERG over time or that would be too hopeful? thank you

By: Donnell Creel

Donnell Creel — Mon, 25 Feb 2013 19:50:49 +0000

If you record no ERG in scotopic (dark) condition, then get a recordable scotopic ERG later usually something was wrong 1st recording. There is very remote chance that at 5 months the rod system was not developed enough, but so remote I have never seen it.

The good news is he now has scotopic (rod) ERGs. Cone dystrophies can be expressed as either a pure cone dystrophy or a cone-rod dystrophy with variable degree of rod dysfunction. The rod dysfunction can develop at a later time.

His acuity can be estimated with a test called a Teller Acuity Test, which you can “Google” to see what is involved.

By: Michelle

Michelle — Sat, 23 Feb 2013 23:03:32 +0000

Sorry I forgot to mention that his vision has continued to improve since December . He has a myopia of -3 at the moment.

Michelle

By: Michelle

Michelle — Sat, 23 Feb 2013 22:59:08 +0000

Hi again Dr Creel,

I was asking in December about my son`s absent ERG at 5 months old. He had a repeat ERG at 12 months which showed normal scotopic responses and abnormal?absent fotopic responses. I am now very confused as I am being told that the diagnosis is not LCA but cone dystrophy. May I please ask your opinion on the ERG? Is it possible to have an absent erg for both scotopic and fotopic responses and to then have a normal scotopic response? Thank you, Michelle

By: Donnell Creel

Donnell Creel — Tue, 11 Dec 2012 20:53:26 +0000

It is possible that decreased rod ERG is due to insufficient dark adaptation, but most people are fairly well dark adapted in 20-30 minutes. On the up side, sometimes the rod dysfunction does not progress to extent of cone dysfunction. All the cone/rod, cone, rod/cone dystrophies vary extensively in both expression and underlying genetic mutations.

By: Ann

Ann — Tue, 11 Dec 2012 13:31:46 +0000

My son is now 3.5 years old. His VA is about 20/100. He developed nystagmus since he was 7 weeks old. He has normal development and no obvious photophobia. The ERG(skin electrode) result showed marked decrease cone response and subnormal rod response,from less than 30 minutes dark adaptation. His doctor said the differential diagnosis are achromatopsia, blue cone monochromatism and cone-rod dystrophy. We have to repeat ERG again. I’m quite concern for cone-rod dystrophy because it can progress, but the doctor said the onset of cone-rod dystrophy is usually about 7-8 yrs old. What do you think about this clinical setting and onset? Is it possible that the subnormal rod response come from not enough dark adapted time?
Thank you so much.

By: Bryan William Jones

Bryan William Jones — Sat, 08 Dec 2012 15:33:16 +0000

Hi Sara,

Not quite sure what you are asking for… Can you be more specific?

By: sara

sara — Sat, 08 Dec 2012 13:31:51 +0000

hi thanks, it was really comprehensive.
may i ask you to help me about the electrical circuit of retinogram if you have it?i will appreciate you if you send for me its circuit.i couldn’t find it on internet.
thanks in advance

By: Michelle

Michelle — Thu, 06 Dec 2012 20:56:44 +0000

Thank you very much for your time and patience.

Kind regards,

Michelle

By: Donnell Creel

Donnell Creel — Thu, 06 Dec 2012 20:14:33 +0000

As I mentioned there is considerable variation in expression of ocular disorders. Maybe your son got lucky.

It is impossible for me to judge quality of the ERG recording, but as I tell patients, electrophysiology is not rocket science.

Nystagmus often dampens as visual system matures.