1. The Effect of Corneal Anterior Surface Eccentricity on Astigmatism after Cataract Surgery Choul Yong Park MD 1 Sung Jun Lee MD 1 Prabjot Channa MD 2 Roy S. Chuck MD, PhD 2 1. Department of Ophthalmology, Dongguk University, Ilsan Hospital 2. Department of Ophthalmology, Montefiore Medical Center, Albert Einstein College of Medicine The authors have no financial interest in the subject matter of this poster

2. Purpose In the pursuit of better control of SIA, in this study, we investigated the relationship between SIA and anterior corneal eccentricity after routine cataract surgery.

3. Materials and Methods 125 Asian eyes Phacoemulsification with 2.8mm clear corneal incision Check preop keratometry (Full Auto Ref-Keratometer RK-F1, Canon, Japan) and preop Scheimpflug corneal image (Pentacam, Oculus, Germany) Eccentricity of anterior corneal surface : Pentacam analysis within 8 mm diameter centered at the visual axis Check postop keratometry (Full Auto Ref-Keratometer RK-F1, Canon, Japan ) Calculate surgically induced astigmatism (SIA) using vector calculation formula Statistics –ANOVA and multiple linear regression analysis

4. Materials and Methods Exclusion criteria –irregular preoperative astigmatism –any defect in the posterior capsule or zonules –post-operative best spectacle corrected visual acuity (BSCVA) less than 20/20 –glaucomatous ocular change, –severe keratoconjunctivitis sicca, –significant corneal pathology and opacity The eyes were grouped according to the amount of SIA. –group 1: the eyes with SIA from zero to 0.25 D, –group 2: the eyes with SIA from 0.26D to 0.5D, –group 3: the eyes with SIA from 0.51D to 0.75D, –group 4: the eyes with SIA from 0.76D to 1.0D, –group 5: the eyes with SIA greater than 1.0D. The characteristics of each group were analyzed and compared.

5. Results 1 Eyes included (N=125) Mean ±SDmaxmin Age 69.5± 8.49150 Preop corneal cylinder 0.93 ± 0.532.500 Eccentricity 0.28 ± 0.280.79-0.82 Central corneal thickenss 534.2±30.6611445 Axial length 23.47±1.0129.3921.35 Postop refractive sphere 0.20±0.701.75-3.25 Postop refractive cylinder -0.85±0.552.750 Postop spherical equivalent-0.23±0.691.13-3.38 SIA (magnitude)0.67±0.452.100 Postop UCVA (Snellen acuity)0.72±0.201.250.125 Table 1. Descriptive data of study eyes UCVA: post-operative uncorrected distance visual acuity, preop: pre-operative, postop: post- operative, SE: spherical equivalent, max: maximum, min: minimum

6. Results 2 Location of Main Incision Superior (min/max) Superior-Nasal (min/max) Superior- Temporal (min/max) Temporal (min/max) Nasal (min/max) p-value Number of eyes 6315112313 age 66.8±8.3 (50/86) 75.7±6.4 (67/91) 71.3±9.4 (52/86) 70.6±8.0 (50/85) 71.7±6.2 (64/83) 0.002 Sex (M/F) 24/392/134/75/184/9 Preop corneal cylinder 1.03±0.58 (0.25/2.5) 0.75±0.48 (0.25/1.75) 0.62±0.33 (0.25/1.25) 0.93±0.48 (0/2.0) 0.94±0.41 (0.25/1.5) 0.135 Preop corneal cylinder axis 112.0±70.772.8±35.141.4±25.989.0±29.921.6±11.60.135 Eccentricity 0.32±0.29 (-0.82/0.79) 0.25±0.22 (-0.28/0.65) 0.39±0.23 (0.05/0.73) 0.26±0.29 (-0.36/0.68) 0.12±0.30 (-0.31/0.79) 0.114 Central corneal thickenss 533.7±30.5 (445/609) 529.1±34.1 (470/606) 548.0±32.2 (489/598) 530.8±29.2 (473/594) 538.5±29.3 (501/611) 0.564 Axial length 23.4±1.17 (21.35/29.39) 23.4±0.70 (22.45/24.99) 23.4±0.81 (22.44/24.60) 23.7±0.90 (22.38/25.50) 23.6±0.87 (22.50/25.80) 0.759 Postop refractive sphere 0.19±0.52 (-1.5/1.25) 0.15±0.41 (-0.5/0.75) -0.05±1.23 (-3.25/0.75) 0.21±0.87 (-2.25/1.25) 0.42±0.87 (-1.75/1.75) 0.619 Postop refractive cylinder 0.82±0.59 (0/2.75) 0.85±0.58 (0/2.00) 0.58±0.37 (0/1.25) 1.00±0.45 (0/1.50) 1.00±0.54 (0.25/2.25) 0.262 Postop spherical equivalent -0.22±0.54 (-1.50/0.88) -0.28±0.40 (-1.25/0.13) -0.34±1.17 (-3.38/0.75) -0.29±0.82 (-3.00/0.88) -0.08±1.00 (-2.88/1.13) 0.982 SIA0.82±0.490.50±0.380.63±0.400.45±0.240.55±0.470.004 Table 2.The comparison among different location of main incision. SIA: surgically induced astigmatism, preop: pre-operative, postop: post-operative, max: maximum, min: minimum, P-value calculated using ANOVA test

7. Results 3 groups Group 1 (min/max) Group 2 (min/max) Group 3 (min/max) Group 4 (min/max) Group 5 (min/max) p-value Number of eyes 193922 23 SIA 0.14±0.090.36±0.080.63±0.070.92±0.091.43±0.27 age 68.2±11.1 (50/91) 71.0±7.6 (52/86) 72.0±6.8 (62/87) 67.3±9.0 (50/84) 67.8±7.2 (51/84) 0.187 Sex (M/F) 24/392/134/75/184/9 Preop corneal cylinder 0.741.03±0.58 (0.25/2.5) 0.75±0.48 (0.25/1.75) 0.62±0.33 (0.25/1.25) 0.93±0.48 (0/2.0) 0.94±0.41 (0.25/1.5) 0.135 Preop corneal cylinder axis 112.0±70.772.8±35.141.4±25.989.0±29.921.6±11.60.001 Eccentricity 0.18±0.29 (-0.22/0.79) 0.20±0.31 (-0.28/0.65) 0.34±0.25 (-0.11/0.70) 0.34±0.28 (-0.36/0.79) 0.44±0.18 (0.25/0.76) 0.006 Central corneal thickenss 533.7±30.5 (445/609) 529.1±34.1 (470/606) 548.0±32.2 (489/598) 530.8±29.2 (473/594) 538.5±29.3 (501/611) 0.564 Axial length 23.4±1.17 (21.35/29.39) 23.4±0.70 (22.45/24.99) 23.4±0.81 (22.44/24.60) 23.7±0.90 (22.38/25.50) 23.6±0.87 (22.50/25.80) 0.759 Postop refractive sphere 0.19±0.52 (-1.5/1.25) 0.15±0.41 (-0.5/0.75) -0.05±1.23 (-3.25/0.75) 0.21±0.87 (-2.25/1.25) 0.42±0.87 (-1.75/1.75) 0.619 Postop refractive cylinder 0.82±0.59 (0/2.75) 0.85±0.58 (0/2.00) 0.58±0.37 (0/1.25) 1.00±0.45 (0/1.50) 1.00±0.54 (0.25/2.25) 0.262 Postop spherical equivalent -0.22±0.54 (-1.50/0.88) -0.28±0.40 (-1.25/0.13) -0.34±1.17 (-3.38/0.75) -0.29±0.82 (-3.00/0.88) -0.08±1.00 (-2.88/1.13) 0.982 Table 3. The comparison among different groups divided by the amount of SIA SIA: surgically induced astigmatism, preop: pre-operative, postop: post-operative, max: maximum, min: minimum, P-value calculated using ANOVA test

8. Results 4 The correlation between the age and eccentricity in all study eyes (125 eyes) The eccentricity of the anterior cornea showed significant negative correlation with the age of the eyes. p=0.008 (Pearson’s rho=-0.236) The correlation between SIA and eccentricity in all study eyes (125 eyes) This scatter plot shows the significant positive correlation between SIA and eccentricity. (p<0.001, Pearson’s rho=0.310) Each cross represents each case. SIA: surgically induced astigmatism

9. Results 5 The comparison of anterior corneal eccentricity between groups divided by the amount of SIA Groups 1 and 2 showed significantly lower eccentricity when compared to group 5. (group 1 vs group 5:p=0.025, group 2 vs group 5:p=0.012) The number inside each column shows the mean value of eccentricity. ANOVA test was used. The correlation between SIA and preoperative amount of corneal astigmatism (diopters) SIA showed significant positive correlation with preoperative amount of corneal astigmatism (preop cylinder). (p<0.001, Pearson’s rho =0.346)

10. Results 6 The comparison of SIA between eyes with different locations of the main incisions Superior incision induced the greatest SIA compared to temporal incision. (p=0.007) The other incision locations (SN, ST, T and N) showed no significant difference in SIA. The number inside each column shows the mean value of SIA. S:superior, SN: superior-nasal, ST: superior-temporal, T: temporal, N: nasal, ANOVA test was used. The correlation between SIA and the eccentricity of anterior corneal surface in eyes with superior location of the main incision. This scatter plot shows significantly positive correlation between SIA and eccentricity. (p=0.028, Pearson’s rho =0.276) Each cross represents each case. SIA: surgically induced astigmatism

11. Conclusion In this study, we found the SIA is affected by several factors in modern cataract surgery. We found that superior location of the main incision induced the greatest SIA compared to other locations. We also found that corneas with high amounts of preoperative astigmatism resulted in greater SIAs compared to corneas with low amounts. Interestingly, we also found that corneas with higher amounts of anterior eccentricity resulted in greater SIAs. These findings lead us to conclude that corneas having both low preoperative astigmatism and low anterior eccentricity (more close to sphere or oblate ellipse shape) may result in relatively the least SIA after cataract surgery.