ILAV   21219
INSTITUTO DE INVESTIGACION EN LUZ, AMBIENTE Y VISION
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Determination of a Scattering Index for Filters That Simulate Cataracts by an Integrative Method. Authentication With the Compensation Comparison Method
Autor/es:
CORREGIDOR, DIEGO; BARRIONUEVO, PABLO A.; JAÉN, MIRTA; ISSOLIO, LUIS A.; COLOMBO, ELISA
Lugar:
Fort Lauderdale
Reunión:
Congreso; ARVO 2010; 2010
Institución organizadora:
The Association for Research in Vision and Ophtalmology
Resumen:
Purpose:In order to find an optimal optical
characterization of different diffusers that are used to simulate
cataracts we determined the scattering index S (S= PSF. θ2)
with an angular scatter-meter between 0° and 90°. These measurements
showed that the function S(θ) did not remaind constant in the interval
for most of the measured filters. Then, the most appropriate way for
calculating a characteristic index would be to consider the integration
of the S function in the range of interest and to obtain a mean value
for S(θ1,θ2)Methods:To
authenticate the proposed method a C-Quant device was used with
different ophthalmic lens (-2 to +4 diopters) what allowed to vary the
area of the glare ring. In order to calculate for the selected
filters,S(θ1,θ2)function was integrated over
glare ring area which grows with lens focus increasing. On the other
hand S value was measured by indirect and direct methods according to
those proposed by de Wit et al (2006) and van den Berg (2009) using the
C-Quant and results were compared.Results:In
general, as the glare disk increasing, S values decreases with the three
methods but direct and indirect methods gave higher values than
integrative method in most of the cases. As the divergence was within
measurement uncertainties the correlation between the proposed method
and the direct or indirect methods is in general good, obtaining R2 ≥0.95
for a straight line of unitary slope and null ordinate fitting in both
cases. As control correlation between data obtained with direct and
indirect methods was calculated and R2 = 0.996 was obtained.Conclusions:These
results confirm our hypothesis that the proposed method is more general
and could be adapted mainly for non homogeneous or very difusive
filters which is important as it could be in correspondence with
advanced cataracts.