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Nicolas Alejandre-Alba, Mayte Ariño, Elisa Perez-Ramos, David Mingo, Sonia Duran, Blanca Garcia-Sandoval, Ignacio Jimenez-Alfaro; Pupil Size And Iol Calculation With Partial Interferometry. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6181.
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© ARVO (1962-2015); The Authors (2016-present)
Eye’s axial length (AL) measurement based on Partial Coherence Interferometry is theoretically not affected by pupil size. Nevertheless the manufacturer’s recommendation is to make IOL calculation without mydriatics. But sometimes, in our everyday practice we sometimes need to calculate IOL after having examined the retina.
30 eyes from 30 patients with cataract and visual acuity below 0,4 were chosen. Two interferometry measurements were taken for each patient: the first one without mydriatics, the second one 30 minutes after one drop of phenilefrine and one drop of tropicamide. Each time, pupil size was measured in the IOL master screen, using the white-white distance as the reference, in order to avoid changes in light intensity. Levene’s test was used to compare the variance of each group of measurements and T test for paired data was used to find statistical differences in pupil size, SNR, standard deviation, AL, spherical equivalent and calculates IOL power.
Pupil size mean was 3,4 mm before the instillation of mydriatics and 7,2 mm after it (p≤ 0,0001). Levene’s test for variance showed no statistical differences in standard deviation (p= 0,94), SNR (p=0,907), AL (p= 0,991), spherical equivalent (p= 0,971) and IOL power (p= 0,999). T test for paired measurements also found no statistical differences for the standard deviation (p= 0,985), SNR (p=0,585), AL (p= 0,993), spherical equivalent (p= 0,986) and IOL power (p= 0,973).
IOL calculation by interferometry is not influenced by pupil size or mydriatics use in patients with cataracts. Future technology may take into account pupil size when calculating IOL power but nowadays it makes no difference in our outcomes.
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