Abstract
Purpose :
Upon literature review, we were unable to find any studies discussing recommendations for the timing of measurements taken before cataract surgery. We believe a study that investigates the longitudinal variability of LENSTAR would enable clinicians to make more informed decisions about testing prior to cataract surgery and when measurements should be updated.
Methods :
This is a retrospective study using the data from the Loyola Ophthalmology LENSTAR, dating from 2016 through the present. Data will be gathered for axial length, central corneal thickness, aqueous chamber depth, and lens thickness. Measurements of the same eye must be at least six months apart. The first set of measurements will be compared to the second measurements to assess change. The Holladay and Barrett II formulas will be used to calculate and recommend a suggested lens for a standard target refraction of -0.5 D for the first set of measurements. Using this same lens, the calculated refractions for the second measurements will be obtained. We will then compare how many eyes will have a different recommended lens to have a refraction closest to -0.5 D.
Results :
Preliminary data has been collected on 112 eyes. A two-tailed non-paired t-test was used to compare the difference in means within each variable. For axial length, the mean initial and subsequent measurements were 23.9mm and 23.9mm respectively, (p = 1.0). For central corneal thickness, the means were 584.4µm and 547.1µm respectively, (p = 0.80). For aqueous depth, the means were 2.6mm and 2.6mm respectively, (p = 1.0). For lens thickness, the means were 4.6mm and 4.6mm respectively, (p = 1.0).
For Holladay, 55/107 eyes were recommended to use a different IOL based upon the second measurements when compared to the first set. For Barrett II, a different IOL was suggested for 49/107 eyes. Average calculated refraction for the originally suggested lens for the first measurements for Holladay is -0.518, and for the second measurements is -0.584. For Barrett II formula, initial calculated refraction is -0.495, compared to -0.584.
Conclusions :
Preliminary data suggests that within each variable there is not significant change in the values over time. However, the recommended lens for each equation changed in a large proportion of eyes, implying that clinicians may benefit from updating measurements closer to surgery. Further conclusions are pending continued data collection and analysis,
This is a 2020 ARVO Annual Meeting abstract.