Mitchell P. Weikert, MD Li Wang, MD, PhD Douglas D. Koch, MD Cullen Eye Institute

1. Ocular functional optical zone following hyperopic LASIK/PRK: Analysis based on polychromatic retinal image quality Mitchell P. Weikert, MD Li Wang, MD, PhD Douglas D. Koch, MD Cullen Eye Institute Baylor College of Medicine Houston, TX Financial disclosure: none.

2. Background • Traditionally, the functional optical zone (FOZ) is analyzed based on corneal topography* • Wavefront-guided treatments correct ocular aberrations on anterior cornea • Optical quality of the anterior corneal surface may not represent retinal image quality of the whole eye • Due to the effect of the internal optics * Holladay & Janes. JCRS 2002; Boxer Wachler et al. JCRS 2002; Racine, Wang & Koch. AJO 2006; Tabernero et al. IOVS 2007

3. Purpose • To investigate the size of the ocular FOZ before and after wavefront-guided hyperopic LASIK/PRK • Based on optical image quality of the whole eye

4. Patients and Methods • Consecutive cases who underwent AMO-CustomVue LASIK or PRK (CV-LASIK/PRK) for Hyperopia by one surgeon between 1/1/05 to 6/1/09 • Inclusion criteria: • Available follow-up at 6 months post-op • CustomVue wavefront measurements ≥6 mm at both pre-op and 6 months post-op

5. Patients • 30 eyes of 21 subjects included • Age: 51 ± 8.4 years (31to 66 years) • Pre-op CV SE: +1.70 ± 0.82 D (+0.20 to +3.53D) • Post-op CV SE: +0.86 ± 0.63 D (-0.53 to +2.10D) • Refractive correction: -0.84 ± 0.57 D (0.-1.755 to +0.35 D)

6. Methods • Based on CustomVue wavefront measurements, ocular wavefront aberrations were calculated for simulated pupils from 2–6 mm in 0.1 mm intervals • Assuming full correction of 2nd order aberrations, optical image quality of higher-order aberrations (HOAs, 3rd-6th order) was evaluated

7. Methods • Using ZernikeTool program (AMO), polychromatic modulation transfer function (MTF) at 9 cyc/deg with Stiles-Crawford effect calculated for 2-6 mm pupils • FOZ defined as the size over which the MTF at 9 cyc/deg was ≥0.18 • MTF ≥ 0.18 maintains visual acuity of ≥ 20/20 Tabernero J, Klyce SD, Sarver EJ, Artal P.IOVS 2007

8. 100 100 100 100 100 100 87 90 77 73 80 70 Preop 60 % of eyes Postop 50 40 30 20 10 0 ≥ 6 ≥ 5 ≥ 4 ≥ 3 FOZ (mm) Results: FOZ FOZ range: pre-op: 5.2 - 6.0 mm post-op: 4.1 - 6.0 mm

9. FOZ Change Following Myopic CV-PRK

10. FOZ vs. 4th-Order Spherical Aberration (SA) Post-op FOZ  with  spherical aberration (r2 = 0.33, P<0.001 )

11. FOZ vs. Higher Order Aberrations (HOAs) Post-op FOZ  with  HOAs (r2 = 0.31, P<0.001 )

12. Change in FOZ vs. Change in SA FOZ  with  SA (r2 = -0.31, P<0.001 )

13. Change in FOZ vs. Change in HOAs FOZ  with  HOAs (r2 = 0.36, P<0.001 )

14. Change in FOZ vs. refractive correction FOZ stable with  refractive correction (r2 = 0.01, P<0.001 )

15. Summary • 26% of eyes had post-op FOZ < 6 mm • 74% of eyes had post-op FOZ ≥ 6 mm • Post-op FOZ positively correlated with SA and negatively correlated with HOAs • Hyperopic FOZ: •  with SA •  with HOAs • No change with  amount of refractive correction

16. Limitations • Results are not correlated with measures of visual function • Analysis only done up to 6-mm zone

17. Conclusion • FOZ following wavefront-guided hyperopic LASIK/PRK: • Increased to area > 6 mm in 17% of eyes • Decreased to area < 6 mm in 20% of eyes • These results may lead to further refinement of treatment parameters • Study investigating optical FOZ following myopic LASIK/PRK presented as additional poster.