Transcript Near Vision Efficacy: Accomodating vs. Conventional IOLs

Financial Interest Disclosure
• I have no financial interest in the
devices discussed in this presentation.
Presbyopic IOL Calculations:
The Aspheric ReSTOR D1 and
Crystalens HD
Jonathan M. Davidorf, MD
Los Angeles, CA
April, 2010
Purpose of Study
• To examine the predictability of
intraocular lens implant (IOL)
calculations in patients undergoing
cataract surgery and implantation of the
Aspheric ReSTOR D1 or Crystalens HD
IOLs.
Background
As the goal of presbyopic intraocular lens (IOL) implants is to achieve a
maximum level of spectacle independence, highly predictable
postoperative refractions are desirable.
In the United States, the
ReSTOR and Crystalens are the two most commonly implanted
presbyopic IOLs. The design of the one-piece hydrophobic acrylic
ReSTOR IOL is based on Alcon’s AcrySof platform and is similar to the
monofocal IOL, the SN60WF. The predictability of ReSTOR IOL power
calculations would be expected to be similar to that of the monofocal
SN60WF. The Crystalens, on the other hand, is a silicone IOL with no
non-presbyopic correcting counterpart. The Crystalens was designed to
move anteriorly and posteriorly inside the eye in order to produce an
accommodative effect. The Crystalens HD is similar in design to the
earlier Crystalens 5-0 model, with the added design element of an
increase in negative spherical aberration in the central 1.5mm of the IOL
optic. The design change was intended to increase depth of focus. While
the mechanism of action of the Crystalens remains an area of debate, the
IOL’s unique design has raised concerns of predictability of power
calculations.
Methods
• Ongoing, non-randomized, unmasked prospective
study
• 64 eyes of 33 pts
• Standard coaxial phaco/IOL, topical anesthesia
• Pts received either Aspheric ReSTOR D1 or
Crystalens HD
• Only eyes with 20/25 or better postoperative BCVA
analyzed.
• No prior ocular surgery
• Data collected at 1 M, 3M, and 6 M postoperatively
Demographics
ReSTOR D1
Crystalens HD
# eyes (pts)
33 eyes (17 pts)
31eyes (16 pts)
Gender (eyes)
*29 F, 4 M
12 F, 19 M
Mean Axial
Length
23.62 + 1.17mm
(21.78 - 25.58 mm)
24.27 + 1.57mm
(22.27-27.78 mm)
Mean Ks
43.38 + 1.33 D
(42.11 - 47.76 D)
43.74+ 1.38 D
(41.32 - 46.34 D)
Eyes with LRIs
14 eyes (42%)
13 eyes (42%)
*no explanation for the gender discrepancy between groups
IOL Calculation Formulas
• SRK-T: 2 variable regression formula
• Haigis: theoretical formula, surgeon/iol
specific constants (“customizable”)
Key Statistic:
Prediction Error of IOL Calculation
formula (1M MRSE – predicted SE)
Results:
Mean Prediction Errors
0.21
0.08
ReSTOR D1
Crystalens HD
-0.24
SRK-T
-0.31
Haigis
Results:
Mean Prediction Errors
ReSTOR D1
Crystalens HD
SRK-T
0.08 + 0.29 D
(-0.72 to 0.67 D)
-0.24 + 0.43 D
(-1.10 to 0.54D)
Haigis
0.21 + 0.27 D
(-0.31 to 0.78 D)
-0.31 + 0.60 D
(-1.70 to 0.72 D)
Prediction Errors:
Comparing the Formulas (p-values)
ReSTOR D1
Crystalens HD
Student’s t-Test
0.06
0.15
ANOVA (F-test)
0.66
0.01
Lower prediction error with SRK-T for both IOLs. Expect Haigis to improve
with additional postop data input. Statistically significant difference in the
spread of data between formulas only for Crystalens HD.
Prediction Errors:
Comparing the IOL Power Predictability
SRK-T
ReSTOR D1
Crystalens HD
0.08 + 0.29 D
(-0.72 to 0.67 D)
-0.24 + 0.43 D
(-1.10to 0.54D)
Student’s t-Test:
0.004
ANOVA (F-test):
0.050
Predictability using SRK-T
100%
88%
90%
77%
67%
48%
ReSTOR D1
Crystalens HD
+ /- 0.25 D
+ /- 0.50 D
+ /- 1 D
Stability of Spherical
Equivalent Refraction (D)
2
1.5
1
0.5
Crystalens HD
0
-0.5
1M
3M
6M
ReSTOR D1
-1
-1.5
-2
*Only eyes with 1, 3, and 6 M data (16 eyes ReSTOR D1, 15 eyes Crystalens HD)
Conclusions
• SRK-T showed lower mean prediction error than Haigis for both
IOLs
• Mean Prediction Errors and variance were lower for the
ReSTOR D1 IOL compared to the Crystalens HD, and the
differences were statistically significant.
• Predictability good with both IOLs (88% of ReSTOR and 77% of
Crystalens eyes within 0.50 D of predicted spherical equivalent)
Approaching the accuracy of LASIK?
• Both IOLs showed excellent refractive stability to 6 months
postoperatively
• Further optimization of theoretical formulas should further
improve predictability
Conclusions
Additional Study Needed:
• Other IOL Calculation Formulas?
• Impact of LRIs
• Accounting for the gender discrepancy
between groups
• Predictability of Crystalens AO