1. Using the ASCRS Post-Refractive Surgery IOL Calculator: A Retrospective Review Amit Patel MRCOphth, Achyut Mukherjee MRCOphth, Vinod Kumar FRCSEd(Ophth) Princess of Wales Hospital, Bridgend, UK The authors have no financial interests with regards to this poster

2. Purpose Assess the value of the ASCRS post-refractive surgery IOL calculator (http://iol.ascrs.org/) in cases where the IOL power was chosen prior to the availability of the calculator

3. Methods (1) 10 eyes of 8 patients were identified from theatre records A retrospective case note review was carried out Pre- & post-refractive and cataract surgery data was noted

4. Methods (2) Data available at the time of cataract surgery was entered into the ASCRS calculator The average IOL power and applicable formulae generated by the calculator were noted The chosen IOL power was compared to the average IOL power generated by the calculator The various applicable formulae were analysed to determine which formula would have given the most accurate refractive outcome

5. Results (1) 3 patients (4 eyes) had incomplete pre- refractive surgery data – 2 patients (3 eyes) had no pre-operative data – 1 patient (1 eye) had no post-operative refractive data

6. Results (2) 9 eyes (90%) were within 1D of the refractive aim The predicted refractive outcome with use of the average IOL power suggested by the ASCRS calculator would have: – Improved in 5 eyes (50%) & worsened in 5 eyes (50%) – Graph 1 – Resulted in 9 eyes (90%) of eyes to be within 1D of refractive aim

7. Post-operative refractive outcomes Chosen IOL vs Average ASCRS IOL Refractive error (SE)

8. Results (3) Of the potential 13 formulae available, an average of 4 formulae per eye were available for use with the given data Graph 2

9. Conclusion (1) The number of available formulae is a testament to the difficulty in IOL calculation in eyes that have previously undergone refractive surgery In this case series, the Shammas method appeared most accurate – however there may be a bias as this was the only applicable formula in 4 eyes (those with incomplete/absent pre-operative data) The lack of available data restricted the number of formulae that could be applied (average of 4 formulae)

10. Conclusion (2) Using the average calculated IOL from the ASCRS calculator did not significantly alter the refractive outcome The calculator was however useful in collating all the available data and presenting the various applicable formulae to the surgeon