Olson
The University of Utah
Moran Eye Cener
Randall J Olson, MD
Professor and Chair of Ophthalmology
CEO, John A. Moran Eye Center
Departments of Ophthalmology and Visual Sciences
65 Mario Capecchi Dr.
Salt Lake City, UT 84132
PH: 801.581-3357
June 11, 2010
Dr. George Beiko
Niagara Health Centre
180 Vine Street, Suite 103
St. Catharines, L2R 7P3
CANADA
Dear George:
I am more then willing to supply information in regard to the research that we have performed on intraocular lens glistenings over the last fifteen years. We as a group are the first ones to publish a study in regard to intraocular lens glistenings (JCRS 1995;22:452). Even in this very early paper we showed that there was a potential for contrast sensitivity loss, which is probably the most important part of visual functioning because that is the ability to discern shades of gray under a low light situation. The work continued on to show that these were easily inducible in the material by temperature reversal (JCRS 1998;24:107 and 2002;27:728); and that the latest single piece IOLs had a greater propensity for severe changes. We did show that very severe glistenings can have inpact on visual acuity (JCRS 2001;27:728); however, visual acuity measurements are a relatively poor measure of what happens with these glistenings. It turns out that most studies today have not shown and impact on visual acuity; however, there have been multiple studies, including a recent one we published in American Journal of Ophthalmology (AJO 2007;144:198) all of which show loss of high contrast sensitivity as well as the fact that these get worse over time. You have already quoted this very important Swedish study where they showed that this was progressing over a period of ten years.
The biggest fuctional impact of these glistenings would have to do with there scattering of light. Good work has been performed by Tom Vandenberg, and optical physicist, in shich he has shown that scattering of light is the biggest cause of loss of vision due to glare. Lab bench studies of hids, in personal conversation, clearly show this with glistening; however, we are now launching a very large study to actually ascertain the impact of these glistenings on stray light, glare and visual quality.
In summary in regard to glistenings, we do know that they occur in the majority if not 100% of all Acrysof lenses over time and that they are clearly continuing to get worse after ten years. No one knows what the steady state might be. We do know that severe glistenings can cause the loss of Snellen visual acuity and that there is a direct correlation between the size and density of glistenings and loss of the ability to differentiate contrast hues in patients.
Another reason why I have been concerned about using Acrysof introacular lenses, as well, has been their higher incidence of dysphotopsia. These unwanted images, as we pointed out in a recent study published in the Canadian Journal of Ophthalmology (CJO 2010;45:140) are the number one cause of patient dissatisfaction today. We have published work on dysphotopsia showing that the hight refractive index Acrysof material clearly significantly increases this complaint among patients (JCRS 2000;26:810, AJO 2003;136:614 and Ophthalmologica 2009;223:475). There are alternatives which certainly decrease any dysphotopsia risk as well as do not have a glistening issue.
Pleas let me know if there is anything further that you might need from me in regard to our ongoing research in this area.
Sincerely,
Randal J Olson, MD
Professor and Chair of Ophthalmology and Visual Sciences
CEO, John A. Moran Eye Center
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