Abstract
Purpose :
Type 2 diabetes (T2DM) is a leading cause of vision loss in working aged Americans. Its precursor, pre-diabetes (preDM), is growing in numbers every year. While it is well known that T2DM causes changes in retinal function early in the disease process, it is likely that some of these changes are actually emerging during preDM. This study evaluates retinal function measures in patients with preDM to determine if there are differences in color vision and contrast sensitivity (CS) present before T2DM is diagnosed.
Methods :
The L’Anthony desaturated D-15 test and Mars Chart CS test were administered on the right eye of 28 subjects; 11 controls (HbA1C <5.7%), 10 with preDM (HbA1C 5.7%-6.4%), and 7 T2DM subjects (either physician diagnosed or with an untreated HbA1c over 6.5%); 6 without retinopathy (ret) and 1 with ret. HbA1c values were measured at the time of the other tests. Color confusion score (CCS) results were calculated from the D-15 using the method developed by Torok. Multivariate regression (which controlled for age differences) was used to evaluate the relationship of HbA1c and the functional measures. ANOVAs were also used to evaluate differences between groups.
Results :
There was an association between both higher CS, lower CCS and lower HbA1c values (p<0.004, r2= 0.38 and p<0.03 r2 = 0.28 respectively). The control group was slightly younger so age was controlled for in these regressions (mean ages for the groups 43.6 ± 9.8, 57.5 ± 10.1 and 53.7 ± 9.4 years respectively). There was a difference between the three groups for their CS scores (p<0.012) with the mean decreasing across the groups (1.77 ± 0.06, 1.70 ± 0.08, 1.59 ± 0.18 logCS). The CCS scores did not differ between the groups on ANOVA (p=0.1) but a trend existed for the preDM and T2DM groups having higher mean scores than the control group (means 1.35 ± 0.40, 1.82 ± 0.70, and 1.94 ± 0.77 for CCS).
Conclusions :
CCS and CS can be abnormal in patients with preDM and correlate with HbA1c levels. This makes these good candidate markers for identifying patients with preDM or at risk for T2DM. These results show that these retinal function changes seen in diabetes can begin occurring before formal diagnosis. Further studies are needed to follow these patients over time to see how and when these metrics change.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.