Abstract
This study was carried out to investigate in vivo the changes
of the human lens autofluorescence (AF) with aging and cataractogenesis.
Measurements were performed in the blue-green AF range (495 nm/520
nm) using a fluorometer designed, built and now clinically tested
in our department.
43 random eyes of 43 healthy volunteers aged 6-86 years, five
of each decade, were studied for effects of aging and 84 eyes of
84 patients with cortical, nuclear, posterior subcapsular or mixed
lens opacities were studied for differences of various cataract
types. The results were compared with the back light scatter values
obtained by the commercially available Interzeag Lens Opacity Meter
701. Also AF and back light scatter of the lens were measured from
122 smoking males aged 57 to 76 years who participated in a cancer
prevention study. The results were compared with the widely used
subjective lens opacities classification system, LOCS III. In addition
data was collected from 30 randomly chosen eyes of as many subjects
with varying degrees of yellow-brown lens coloration in an otherwise
healthy eye. We studied the influence of lens yellowing expressed
by means of lens AF on visibility of retinal nerve fiber layer
in black-and-white images.
Lens AF profile consists of anterior and posterior peaks and
a central plateau. The height of the anterior peak was used as
a measure of the maximum AF value. The square root of the ratio
between the posterior and the anterior AF peaks was used for estimating
the lens transmission. Our technique was highly reproducible. The
coefficient of variation was 3.9% for maximum AF and 2.9% for
the lens transmission index.
Both the maximum AF and light scatter were exponentially increased
with age (r = 0.95 and 0.94, respectively; p < 0.0001).
According to the regression line of AF begins to increase in early
childhood. It appears by extrapolation to be absent at birth. In
contrast light scatter in the lens was present even in young children.
The lens transmission for blue-green light, determined from the
lens AF curve, was almost unchanging with age up to 60 years. Thereafter
it decreased rapidly and the interindividual variation increased.In
cataractous lenses the mean AF and scatter values differed statistically
significantly from those of age matched healthy controls. The highest
AF values were measured in nuclear cataracts where AF was also
related to visual acuity and an increasing yellow-brown colour
of the nucleus. About half of the total variation of the transmission
index values could be accounted for by changes in nuclear colour
as assessed by the LOCS III grading system. The transmission index
provided a more precise prediction about nuclear colour and opalescence
than age or light scatter did.
In cortical cataracts the AF curve was low and flattened and
the maximum AF value was significantly lower than in the age matched
control eyes. The highest light scatter values were measured from
cortical cataracts, but the correlation between LOCS III cortical
grades and light scatter values was rather weak.
Posterior subcapsular cataracts cannot be quantified either
with AF or with light scatter measurements. Lens yellowing, expressed
as lens AF, had an actual effect on retinal nerve fiber layer visibility.
AF measurements provided a better prediction about the visibility
score than age or visual acuity did.
The results of the present study indicate that the lens autofluorescence
measurement may be a useful additional tool together with a subjective
grading system in the follow-up of optical changes occurring in
the nuclear region of the lens.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn951-42-5267-5 |
| Date | 21 May 1999 |
| Creators | Siik, S. (Seppo) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 1999 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/0355-3221, info:eu-repo/semantics/altIdentifier/eissn/1796-2234 |
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