Lens status and degree of lens opacity influence laser flare photometry (objective tyndallometry)

Abstract

Purpose Objective tyndallometry using laser flare photometry can be utilized e.g., in management of uveitis. Previous studies showed a significant difference in flare values between pseudophakic and phakic eyes. We investigate a potential association between the degree of lens opacification and flare value in a large cohort phakic eyes. Methods Retrospective, non-interventional single center study. Laser flare values of 460 healthy fellow eyes from two large cohorts (primary rhegmatogenous retinal detachment (RRD), macular holes (MH)) were correlated with lens status, degree of lens opacity, and age. Results Out of 460 patients (mean age 64.6 ± 11.2, 57% male) 30.4% were pseudophakic (70.2 ± 10.9) and 69.6% phakic, of which 47.8% showed a clear lens (57.3 ± 9.1), 43.2% an mild cataract (65.2 ± 9.0) and 9.0% a moderate cataract (73.5 ± 9.0). In pseudophakia, flare (8.14 ± 4.6 pc/ms) was significantly higher compared to phakia (6.4 ± 3.9 pc/ms; p < 0.001). In phakic eyes, flare values increased significantly with increasing lens opacity (clear lens 5.3 ± 2.8 pc/ms; mild cataract 7.0 ± 4.0 pc/ms; moderate cataract 9.5 ± 6.1 pc/ms; p < 0.001). In clear lenses and mild cataract, age correlated significantly with flare (two-sided, p < 0.001, clear lenses R = 0.3; mild cataract R = 0.4). In clear lenses, flare values increased with age by 0.09 per year, in mild cataract by 0.17 (regression coefficients). No significant correlation was found between age and flare value in moderate cataract and pseudophakic eyes. Conclusion The level of objective tyndallometry seems to be dependent on lens status, degree of lens opacity and age. These factors should therefore be taken into account when interpreting laser flare values in the future.

Laser Flare Photometry in Primary Rhegmatogenous Retinal Detachment: an Evaluation of 2487 Cases

“…Presumably because of the large size of the cohort of 2,487 patients in our analysis, we were able to identify additional influencing factors on the flare value compared with the studies of Schröder et al (59 patients) 12 and Schöneberger et al (266 patients). 23,24 Elevated laser flare values in eyes with RRD and their correlation with the extent of retinal detachment are likely because of pronounced disruption of the blood-aqueous barrier. We have published this finding before in a smaller scale.…”

Relevanz der Laser-Flare-Photometrie bei retinalen Pathologien

“…In a further study, we examined the lens status in healthy eyes, to consider and characterize the relationship between the degree of lens opacity and laser flare values independently of other factors. The examination results of 460 healthy eyes showed a significant increase in the laser flare value with increasing lens opacification of the natural lens 47 . Given that pseudophakic eyes exhibit heterogeneous flare values in patients between 39 to 94 years of age with no significant association of age and Laser Flare Meter measured flare values, it can be extrapolated that lens opacity has a greater impact on flare value than age.…”

“…Eyes with extended periods of RRD and higher laser flare values show increased levels of inflamma-tion with the infiltration of activated macrophages over time, and there is an increased risk of PVR formation [46]. Interestingly, significantly higher flare values were measured in pseudophakic eyes compared to phakic eyes [43,44,47]. This may be explained by the easier perfusion from the posterior to the anterior chamber of the eye in pseudophakia.…”

“…In einer weiterführenden Studie untersuchten wir den Linsenstatus bei gesunden Augen, um den Zusammenhang zwischen dem Grad der Linsentrübung und den Laser-Flare-Werten unabhängig von anderen Faktoren zu betrachten und zu charakterisieren. Die Ergebnisse von 460 gesunden Augen zeigten einen signifikanten Anstieg des Laser-Flare-Wertes mit zunehmender Linsentrübung der natürlichen Linse [47]. Da bei pseudophaken Augen eine breite Streuung der Flare-Werte von 39 bis 94 Jahre vorliegt, ohne dass das Alter einen signifikanten Einfluss auf die gemessenen Flare-Werte hat, ist davon auszugehen, dass die Linsentrübung einen größeren Einfluss auf die Flare-Werte hat als das Alter.…”

“…Augen mit längerer Dauer der RRD und höheren Laser-Flare-Werten weisen im Laufe der Zeit eine Zunahme der Entzündung mit Infiltration von aktivierten Makrophagen auf, und es kommt zu einem erhöhten Risiko für PVR-Bildung 46 . Interessanterweise wurden in den Untersuchungen bei pseudophaken Augen ebenfalls signifikant höhere Flare-Werte gemessen im Vergleich zu phaken Augen 43 , 44 , 47 . Eine Vermutung ist die erleichterte Perfusion von der hinteren zur vorderen Augenkammer bei Pseudophakie.…”