1. 성모병원 안센터
CHANGES IN ASTIGMATISM RELATIVE TO IOL HAPTIC INSERTION AXIS IN WITH-THE-RULE AND AGAINST-THE-RULE ASTIGMATISM PATIENTS
Hyun Seung Kim, M.D.
Department of Ophthalmology, St. Mary’s hospital,
The Catholic University of Korea
Authors have no financial interest.

2. Purpose
To compare astigmatic outcomes caused by axis change of inserted IOL haptic during clear corneal temporal incision cataract surgery for patients with WTR and ATR astigmatism
IOL haptic insertion at 180° vs. 90° axis
IOL haptic insertion at 180° axis at 90° axis

3. Materials and Methods
138 patients (151 eyes) with LOCS III, No 2-3 cataract
Phacoemulsification cataract extraction + PCL insertion through 3 mm temporal clear corneal incision by one surgeon.
No suture was done.
Pupil dilatation was done at POD # 1 month
: When IOL rotation was detected from original axis (out of 180±10° or 90±10°), the patient was excluded from the study.
Patient selection criteria (at pre-, and post-operative state)
WTR astigmatism : Steep axis range 90±20°
ATR astigmatism : Steep axis range 180±20°

4. Materials and Methods
Patients divided into 4 groups according to preoperative astigmatism axis (WTR or ATR) and IOL inserted axis (Haptic in 180° or 90°).
Group I : preoperative WTR astigmatism + IOL haptic axis at 180° (38 eyes)
Group II : preoperative WTR astigmatism + IOL haptic axis at 90° (34 eyes)
Group III : preoperative ATR astigmatism + IOL haptic axis at 180° (36 eyes)
Group IV : preoperative ATR astigmatism + IOL haptic axis at 90° (43 eyes)
3 types of IOLs (Alcon acrySof SA60AT; Rayner C-flex™; AMO Tecnis ZA9003) were inserted in the bag.
Astigmatic changes were compared by Autorefractor (BK-F1, Canon) and Topography (Orbscan II, Orbtek) at preoperative and postoperative 1 day, 1 week, 1 month, 2 months.

5. Results ; Astigmatisms in WTR & ATR groups
Haptic 180° (Group I)
Haptic 90° (Group II)
P-value
Autorefractor
Preoperative
Postoperative 1 week
Postoperative 1 month
Postoperative 2 months
1.32±1.17
1.00±0.73
1.01±0.77
1.01±0.81
1.46±1.09
1.34±1.09
1.49±1.11
1.53±1.30
0.971
0.051
0.050
0.048
Topography
1.20±1.14
1.34±0.88
1.42±0.95
1.29±0.97
1.30±0.79
1.56±1.11
1.61±1.07
1.65±1.05
0.321
0.129
0.585
ATR
Haptic 180° (Group III)
Haptic 90° (Group IV)
P-value
Autorefractor
Preoperative
Postoperative 1 week
Postoperative 1 month
Postoperative 2 months
1.23±0.85
1.20±0.51
1.21±0.56
1.22±0.40
1.34±0.76
1.18±0.63
0.97±0.56
0.91±0.53
0.338
0.607
0.046
0.034
Topography
1.41±0.48
1.32±0.17
1.25±0.09
1.19±0.10
1.26±1.09
1.12±0.63
0.99±0.57
1.06±0.54
0.310
0.291
0.170
0.302

6. Results ; Astigmatisms in WTR & ATR groups
Refractive Astigmatism by Autorefractor
Corneal Astigmatism by Topography
WTR Group I & II
WTR Group I & II
Refractive Astigmatism by Autorefractor
Corneal Astigmatism by Topography
ATR Group III & IV
ATR Group III & IV

7. Vector Analysis of Mean Refractive Astigmatism
WTR
Haptic 180° (Group I)
Haptic 90° (Group II)
P-value
Autorefractor
Postoperative 1 day
Postoperative 1 week
Postoperative 1 month
Postoperative 2 months
1.17±0.94
1.00±1.01
1.02±0.87
0.96±0.77
1.35±1.21
1.12±0.98
1.32±0.95
1.49±1.10
0.321
0.217
0.049
0.017
Topography
1.05±1.15
1.07±1.23
1.15±1.10
0.90±1.04
0.97±1.11
1.04±0.75
0.766
0.723
0.667
ATR
Haptic 180° (Group III)
Haptic 90° (Group IV)
P-value
Autorefractor
Postoperative 1 day
Postoperative 1 week
Postoperative 1 month
Postoperative 2 months
1.54±0.91
1.47±0.67
1.49±0.54
1.35±0.76
1.29±0.96
1.37±0.85
1.10±0.75
1.06±1.02
0.255
0.170
0.046
0.029
Topography
0.95±0.85
0.62±0.72
0.62±0.93
1.01±0.88
0.72±0.83
0.74±0.577
0.752
0.699
0.532

8. Vector Analysis of Mean Refractive Astigmatism
In WTR Patients
In ATR Patients
WTR Group I & II
ATR Group III & IV

9. Refractive Astigmatism
Mean Astigmatism Change
According to IOL Type in ATR Patients
IOL Type
Refractive Astigmatism
Corneal Astigmatism
Single-piece
hydrophobic acrylic IOL
(Alcon acrySof SA60AT)
hydrophilic acrylic IOL
(Rayner C-flex™)
Three-piece
acrylic optic
with PMMA haptic IOL
(AMO Tecnis ZA9003)

10. Summary WTR astigmatism group with Haptic axis 180°
Topography : Corneal Astigmatism ↑
Autorefractor : Total Astigmatism ↓
May be a net effect of Ocular residual astigmatism ↓(IOL effect ?)
ATR astigmatism group with Haptic axis 90°
Topography : Corneal Astigmatism ↓
Autorefractor : Total Astigmatism ↓↓
May be a net effect of Ocular residual astigmatism ↓ (IOL effect ?)

11. Our Hypothesis of IOL Effect
Inserting the IOL in the bag
Capsule bag diameter < Total IOL length
→ Angulation of IOL, Stretching of posterior capsule
→ More astigmatism perpendicular to IOL haptic axis
Development of With-the-Rule effect

12. Conclusions
When performing cataract surgery by clear corneal temporal incision, inserting IOL axis parallel to preoperative astigmatism axis could minimize the surgically induced astigmatism.
The effect was greater with one-piece acrylic IOL than three-piece PMMA haptic IOL.
Considering the ocular residual astigmatism after cataract surgery may be important when inserting toric, aspheric and multifocal IOLs.
And the possibility that IOL haptic insertion axis may affect the ocular residual astigmatism should be considered when performing cataract surgery.