Update on Longitudinal study of cataract using the Dynamic Light Scattering: Cataracts progress with loss of the molecular chaperone, alpha crystallin proteins

Abstract

Purpose: : To do an interim analysis of longitudinal data on cataract progression using the NASA-NEI Dynamic Light Scattering device to monitor the molecular chaperone alpha crystallin protein in the lens.

Methods: : We are currently conducting an IRB approved longitudinal study of age related cataracts. All tenets of the Declaration of Helsinki are being followed and all patients gave informed consent. All patients undergo a comprehensive dilated eye exam every 6 months including: slit lamp grading of their lenses using the Age Related Eye Disease Study (AREDS) clinical lens grading system, lens imaging and densitometry using the Pentacam Scheimpflug system, and NASA-NEI Dynamic Light scattering (DLS) measurement of the Alpha Crystallin Index (ACI) in the nucleus. We performed an interim analysis on 76 eyes from patients ages 40-80 who have had at least 3 visits (ranging from 3-6 visits).

Results: : We developed a random effects model to determine the correlation between the progression or non progression of AREDS lens grading or Scheimpflug density with the level of the ACI. We found that eyes with a ACI baseline level of 8% or less had greater probability of developing a cataract than those eyes with ACI higher than 8% using the AREDS clinical grading system (p<0.0001) but not with the Pentacam Scheimpflug. However, eyes that had ACI of 8% or less at baseline and a 6% or more decline in ACI per year had significant progression of cataract using both AREDS clinical grading and Pentacam Scheimpflug imaging compared to those that only had low ACI but no decline in ACI (p=0.04).

Conclusions: : Our interim analysis suggests that even with low ACI in the lens, as long as the ACI remains stable and does not decline, the lens may remain clear. However, once one has a low ACI and it declines over time, then the probability of cataract formation increases. The DLS can be useful in determining the role played by alpha crystallin anti cataract protein in cataractogenesis. Early detection of precataractous changes could be of great value in the future, to help guide an early intervention that could hopefully prevent or delay the developement of cataracts.

Keywords: crystallins • cataract • chaperones