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Henk A Weeber, Marrie Van der Mooren, Selma Boersma, Aixa Alarcon, Patricia A Piers; Spurious image methodology: from optical bench to clinical assessment.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1140.
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© ARVO (1962-2015); The Authors (2016-present)
Pseudophakic patients implanted with presbyopia correcting (PC) lenses may experience photic phenomena originating from spurious images. Specific spurious images that occur are the halo(s) originating from bifocal or trifocal lenses, which may be bothersome for patients. Photometric evaluation of halos can be evaluated pre-clinically. However, the challenge remains to translate pre-clinical evaluation to the potential bothering effect that may be experienced by patients.
Methodology has been presented in the past for measuring the size and light intensity of halos (van der Mooren, ARVO 2016). In this study we evaluated the robustness of this method. Specifically, we evaluated the reproducibility and the potential of the method to distinguish between halo performance of different lens designs. Measurement data of a monofocal IOL and a multifocal IOL were collected retrospectively. The measurement data were processed in order to obtain the relative light intensity (RLI) as a function of visual angle. RLI was expressed in a logarithmic scale. Reproducibility was calculated, and the difference between halo of the monofocal IOL and a multifocal IOL was evaluated using a student-t test.
Ten monofocal IOLs and 9 multifocal IOLs were measured on different days over a time period of 5 years (2010 to 2015). Within a visual angle of 1 degree, the dynamic range for the monofocal IOL was 10 times larger as compared to the multifocal IOL (monofocal IOL: 4.18 decades, multifocal IOL: 3.30 decades). The reproducibility of the monofocal IOL and the multifocal IOL were not significantly different (P=0.36). The pooled reproducibility standard deviation is 0.17 decades.The difference in RLI between the two IOL models varied from 0 to 1.3 decades. The difference was statistically significant for visual angles of 0.1 degree and larger. Results indicate that more subtle differences between lens designs can also be measured. Comparison with literature data indicates that the reproducibility is considerably better than the variance in clinically measured halos (Pieh et al. 2001), while also the clinically measured halos noticed a clear distinction between multifocal and monofocal halo.
The in-vitro halo measurement method described is capable of providing halo intensity profiles. The reproducibility seems adequate for measuring small differences between lens designs.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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