Abstract
The time-resolved autofluorescence of the eye is used for the detection of metabolic alteration in diabetic patients who have no signs of diabetic retinopathy. One eye from 37 phakic and 11 pseudophakic patients with type 2 diabetes, and one eye from 25 phakic and 23 pseudophakic healthy subjects were included n the study. After a three-exponential fit of the decay of autofluorescence, histograms of lifetimes τ(i), amplitudes α(i), and relative contributions Q(i) were statistically compared between corresponding groups in two spectral channels (490 < ch1 < 560 nm, 560 < ch2 < 700 nm). The change in single fluorophores was estimated by applying the Holm–Bonferroni method and by calculating differences in the sum histograms of lifetimes. Median and mean of the histograms of τ(2), τ(3), and α(3) in ch1 show the greatest differences between phakic diabetic patients and age-matched controls (p < 0.000004). The lack of pixels with a τ(2) of ∼360 ps, the increased number of pixels with τ(2) > 450 ps, and the shift of τ(3) from ∼3000 to 3700 ps in ch1 of diabetic patients when compared with healthy subjects indicate an increased production of free flavin adenine dinucleotide, accumulation of advanced glycation end products (AGE), and, probably, a change from free to protein-bound reduced nicotinamide adenine inucleotide at the fundus. AGE also accumulated in the crystalline lens.
Highlights
Detection of the earliest signs of diabetic retinopathy (DR) increases the probability of reducing further pathological developments, provided that an appropriate therapy will be administered.[1,2]Apoptosis of vascular and neural cells has been reported for the early onset of DR.[3]
Because the fluorescence decay depends on age,[20,21] the only subjects who were included in the age-matched comparison between diabetic patients who have no signs of DR and healthy subjects were older than 40 years
The bluer color in the images of the patient with diabetes indicates a prolongation of the lifetimes
Summary
Detection of the earliest signs of diabetic retinopathy (DR) increases the probability of reducing further pathological developments, provided that an appropriate therapy will be administered.[1,2]Apoptosis of vascular and neural cells has been reported for the early onset of DR.[3]. No change in concentration of reduced nicotinamide adenine dinucleotide (NADH) was found between excited retina of diabetic rats and controls.[6] Further studies were performed on excited retinas of rats under euglycemic and hyperglycemic conditions as well as in vivo on diabetic rats.[7] In these studies, no elevated cytosolic NADH/ NAD ratio was found under hypoglycemic conditions nor in diabetes, both in vitro and in vivo. They found an increased polyol synthesis and metabolites upstream of glucose like the sorbitol pathway, which decreases NADPH
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