Comparative%20Study%20of%20the%20Aspheric%20Akreos%20Adapt%20AO%20IOL%20Versus%20the%20Spherical%20Akreos%20Adapt%20IOL

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Comparative Study of the Aspheric Akreos Adapt AO
IOL Versus the Spherical Akreos Adapt IOL

• Maghizh Anandan
• Martin Leyland

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Purpose

• Standard IOLs provide good visual acuity but
  they often increase spherical aberration and
  reduce contrast sensitivity.
• This study compares the optical performance of
  the aberration free Akreos Advanced Optic IOL
  (AO) with the conventional spherical Akreos
  Adapt IOL (AA).

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Methods

• Twenty five patients requiring bilateral cataract
  surgery were enrolled in to this prospective,
  intra-individual comparative study.
• One eye received the AO lens and the other eye
  the AA control lens according to the
  randomisation table.
• Study was double masked. Neither the patients nor
  the examiner at the post-op visit knew which eye
  had the aspherical IOL.
• Quality of vision was tested by visual acuity,
  contrast sensitivity and quality of vision
  questionnaire
• All patients were operated on by the same surgeon
  (M.L) using the same technique and were followed
  up for at least 3 months
• Written informed consent was obtained from all
  patients before surgery, and the study was
  approved by the local ethics committee.
• Preoperative and postoperative evaluations
  included uncorrected distance visual acuity,
  (BSCVA), spherical equivalent (SE), slitlamp
  biomicroscopy, applanation tonometry, fundus
  examination, B-scan biometry
• Clinical data were collected preoperatively and 1
  and 3 months postoperatively.
• Unaided and best spectacle-corrected visual
  acuity , contrast sensitivty

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Contrast sensitivity

• Contrast sensitivity was measured using SIFIMAV
  test screen, containing sinusoidal gratings of 5
  spatial frequencies with 8 contrast sensitivity
  levels each.
• The examinations were performed unilaterally at a
  distance of 2.5 m with BSCVA and an un-dilated
  pupil. All measurements were performed under the
  same conditions by an examiner who was unaware of
  the type of IOL implanted.

Questionnaire

• All patients were given a questionnaire at the
  last follow-up
• The questionnaire was designed to determine
  whether a patient was experiencing any form of
  dysphotopsia in any of the eye (Light-caused
  glare, Increase in eye sensitivity, Unwanted
  images)
• If the patients said yes to the above in any/both
  eye they will answer further questions to
  determine the nature and level of dysphotopsia by
  points system.
• Light related glare was scored as 0 if none, 1
  for minimal, 2 for annoying and 3 for
  debilitating.
• This questionnaire was been developed by Tester
  and co authors (Dysphotopsia in phakic and
  pseudophakic patients  incidence and relation to
  intraocular lens type.J. Cataract Refract Surg
  2000 26 810-816)

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Analysis

• For statistical analysis of visual acuity,
  logarithm of minimum angle of resolution (logMAR)
  acuity values were used.
• Similarly, the recorded contrast sensitivity
  values were transformed into log values.
• The 2 IOLs were compared between eyes
  intra-individually.
• P value less than 0.05 was considered
  statistically significant.

Results

• 46 eyes of 23 patients were included in the study
• 2 patients died after bilateral surgery but
  before assessment were completed and hence
  excluded from study
• 7 patients(30) were men, and 16 (70 ) were
  women
• The mean age was 77 years (range 68 to 90 years).
• All patients completed the 3-month follow-up.
• There were no intra-operative complications
• 16 eyes underwent limbal relaxing incisions (7 in
  AO group and 9 in AA group)

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Contrast sensitivity
Visual acuity
Pre-operative Mean logMAR BSCVA was 0.49 AA and
0.45 AO (P 0.67) Post-operative (3
months) Mean logMAR unaided VA was 0.20 AA and
0.24 AO (P 0.60) Mean logMAR BSCVA was 0.06 AA
and 0.07 AO (P 0.57) Mean sperical equivalent
refraction -0.37 AA and -0.20 AO (P 0.60)
AA IOL AO IOL P value
1.5 cpd 1.37 1.32 0.22
3 cpd 1.59 1.63 0.46
6 cpd 1.64 1.65 0.89
12 cpd 1.20 1.25 0.61
18 cpd 0.87 0.91 0.74
There was no statistical differences in any of
the spatial frequencies
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Questionnaire - Analysis

• No statistical difference in light-related glare
  score in either of the IOL
• Both lens performs well and patients were
  generally very satisfied
• Two out of 11 patients who drive found it
  difficult to drive at night due to glare ( One in
  each IOL type).

AO IOL AA IOL
Glare scoring 1.94 1.78
Glare 42.1 42.1
Sensitivity 36.8 36.8
Unwanted images 31.5 21
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Conclusion

• No statistically significant differences were
  found between aspherical and spherical IOLs in
  postoperative VA and refraction.
• Contrast sensitivity was performed with an
  un-dilated pupil and best spectacle correction in
  normal room light condition to create a more real
  life situation. There were no statistical
  differences at any of the spatial frequencies.
• The questionnaire analysis showed that the
  patients in our study were very satisfied with
  the quality of vision with both IOLs, with a low
  incidence of adverse visual phenomena.

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Discussion

• Standard intraocular lenses have a positive
  spherical aberration (SA) that, when added to the
  positive SA in the normal cornea, increases
  ocular SA. Aspherical IOLs have been designed to
  compensate for the positive SA of the cornea
• Advanced Optics (AO) aberration-free aspheric
  intraocular lens is a Hydrophilic acrylic lens
  with a 360-degree square edge. Both the anterior
  and posterior surfaces are aspheric and are
  designed so that the lens itself has no spherical
  aberration.
• Theoretical advantages of this IOL
• Does not contribute to any pre-existing
  higher-order aberrations as its surface is
  aspherical
• If the IOL is decentered it does not induce other
  aberrations, such as coma or astigmatism
• There are other lenses on the market with
  negative spherical aberration, which are designed
  to offset the average corneal spherical
  aberration.
• One has to remember when using such lenses, that
  in some cases of highly prolate corneas, the
  patient will have an end result of considerable
  negative spherical aberration rather than a
  neutral offset.

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Discussion

• We made a significant effort to reduce the bias
  that can occur in comparative clinical studies by
  making our study an intra-individual comparison,
  using the same IOL material manufactured by the
  same company, and having the same surgeon perform
  bilateral surgery using an identical surgical
  technique.
• Many studies have shown better contrast
  sensitivity measurements with aspherical IOL
  especially in mesopic conditions. We performed
  the contrast sensitivity with an un-dilated pupil
  and best spectacle correction only in normal room
  light condition. This may be the reason why we
  did not show any statistical difference in
  contrast sensitivity but when asked which eye the
  patient preferred in terms of overall vision,
  only 33.3 were AO IOLs. Therefore, it remains
  questionable whether any significant differences
  in contrast sensitivity have clinical relevance
  and what it means for the patient.
• In a recent large multicenter study Akreos Adapt
  Advanced Optics (SA 0.00 µm, Bausch Lomb Inc)
  and Tecnis Z9000 (SA -0.27 µm, Advanced Medical
  Optics, Inc.), were compared. The differences in
  eye preference and visual disturbance between the
  2 IOLs favored the Akreos AO. This was
  interesting considering the results of the
  wave-front analysis, in which the total higher
  order aberration, in particular the spherical
  aberration, was significantly lower in eyes with
  the Tecnis Z 9000 IOL. They concluded that
  maximum reduction of spherical aberration does
  not correlate with the perceived visual quality
  of the eye having surgery.

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Discussion

• Limitations of our study are that, we could not
  perform wave front analysis on all patients and
  hence not included in the analysis. However this
  would have been only theoretical as several
  studies have shown that better final spherical
  aberration does not correspond to better vision.
• Contrast sensitivity was not performed in mesopic
  conditions for comparison but we included
  specific questions about night vision including
  driving at night, in the questionnaire to
  ascertain the quality of vision and contrast in
  mesopic conditions and found no statistical
  differences.
• Another limitation is that this study assumed
  that the IOLs were well centered and not tilted
  decentration of IOLs induces coma, which may
  affect the final outcome in that eye.

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Discussion

• The design of this study, with bilateral surgery
  and randomized implantation of the 2 IOLs, was
  chosen to minimize the effects of factors other
  than the IOLs such as ocular dominance or
  refraction deviations, which could affect the
  outcomes. The double-masking also likely
  minimized bias, particularly in the results of
  the patient questionnaires.
• Despite this, we found no differences between the
  IOLs in low-contrast visual acuity or contrast
  sensitivity.
• The patients' awareness of having different IOLs
  in the right eye and left eye may have increased
  their awareness of minor differences between the
  eyes. Still, about half the patients reported no
  difference between the eyes, which is probably
  because of the patients' high level of overall
  satisfaction with the surgical results, visual
  improvement, and IOL performance.
• In summary, the Akreos AO IOL and Akreos IOL gave
  similar contrast visual acuities as well as
  photopic contrast sensitivities.
• Refrences
• L. Wang et al, Optical aberrations of the human
  anterior cornea, J Cataract Refract Surg 29
  (2003), pp. 15141521.
• Visual and optical performance of the Akreos
  Adapt Advanced Optics and Tecnis Z9000
  intraocular lenses Swedish multicenter study,
  Journal of Cataract Refractive Surgery , Volume
  33, Issue 9, September 2007, Pages 1565-1572
• Custom optimization of intraocular lens
  asphericity Journal of Cataract Refractive
  Surgery , Volume 33, Issue 10, October 2007,
  Pages 1713-1720
• Optical performance of 3 intraocular lens designs
  in the presence of decentration, J Cataract
  Refract Surg 31 (2005), pp. 574585.
• Effect of decentration of wavefront-corrected
  intraocular lenses on the higher-order
  aberrations of the eye, Arch Ophthalmol 123
  (2005), pp. 12261230.
• Ocular aberrations and contrast sensitivity after
  cataract surgery with AcrySof IQ intraocular lens
  implantation Clinical comparative study.J
  Cataract Refract Surg. 2007 Nov33(11)1918-24.