Pseudoaccommodative Cornea Treatment
Using the NIDEK EC-5000 CXIII Excimer
Laser in Myopic and Hyperopic Presbyopes
Edward Uy, MD; Rory Go, MD
ABSTRACT
PURPOSE: To investigate the refractive outcomes and
spherical aberration of multifocal LASIK to create a
distant-dominant center and near-dominant periphery in
hyperopic, myopic, and emmetropic presbyopia.
METHODS: One hundred ninety-five eyes with myopic
presbyopia and 119 eyes with hyperopic or emmetropic
presbyopia that underwent LASIK or epithelial LASIK
(epi-LASIK) were assessed out to 3 months postoperatively. All eyes underwent the pseudoaccommodative
cornea (PAC) treatment using aspheric ablation profiles
and wavefront correction with the NIDEK CXIII excimer
laser. Mean preoperative spherical equivalent refraction
was 3.802.10 diopters (D) for myopic presbyopia
and 1.000.92 D for hyperopic or emmetropic presbyopia.
RESULTS: Mean postoperative spherical equivalent
refraction was 0.400.77 D for myopic presbyopia
and 0.150.62 D for hyperopic or emmetropic presbyopia. Functional vision, defined as 20/30 or better
distance uncorrected visual acuity (UCVA) combined
with J3 or better near UCVA, was achieved in 162 (83%)
eyes with myopic presbyopia and 103 (87%) eyes with
hyperopic or emmetropic presbyopia. An induction of
0.312 µm of spherical aberration was noted at 6 mm
for myopic presbyopia treatments and 0.016 µm for
hyperopic presbyopia treatments.
CONCLUSIONS: The distance-dominant center used for
PAC treatments is effective in emmetropic, myopic, and
hyperopic presbyopia. The induced spherical aberration
allows for depth of focus in patients with presbyopia.
[J Refract Surg. 2009;25:S148-S155.]
E
xcimer laser treatment of myopia, hyperopia, and astigmatism is a safe and effective procedure.1 However,
the treatment of presbyopia remains a challenge. Laser
algorithms for presbyopia combine multiple hyperopic and myopic treatments at different treatment zones to create a multifocal
cornea.2,3 Presbyopic treatments create a pseudoaccommodative
cornea to allow near vision in distance-corrected presbyopia.3
Both distance-dominant central corneas and near-dominant central corneas have been proposed to treat presbyopia.2,3
Limited success with myopic or hyperopic presbyopia has been
reported, with neither approaching the outcomes achieved
with primary LASIK.4,5 In this study, we report on the refinement of a distance-dominant central cornea algorithm called
the pseudoaccommodative cornea (PAC)3 for the treatment of
myopic, hyperopic, and emmetropic presbyopia. The refinement is the inclusion of the OPDCAT algorithm. By altering
the corneal surface, PAC increases corneal spherical aberration
(Z12), which results in a multifocal image that is imaged on
the retina.3 This multifocality creates a peripheral near zone
allowing functional near vision with central distance vision.
PATIENTS AND METHODS
PATIENTS AND EVALUATION
This was a retrospective study of 314 presbyopic eyes of
158 patients who underwent PAC treatment using the NIDEK
Advanced Vision Excimer Laser platform (NAVEX) (NIDEK
Co Ltd, Gamagori, Japan) at the Advanced Vision Laser Center in Manila, Philippines. The NAVEX consists of the OPDScan wavefront aberrometer and corneal topographer (NIDEK
Co Ltd), EC-5000 CXIII excimer laser (NIDEK Co Ltd), and
From Advanced Vision Laser Center, Manila, Philippines.
The authors have no financial interest in the materials presented herein.
Presented at the 2008 World Ophthalmology Congress; June 29, 2008; Hong
Kong, China.
Correspondence: Edward Uy, MD, Advanced Vision Laser Center, Ste 10041006 Medical Plaza, Amorsolo St, Manila, Philippines. Tel: 63 844 3500;
E-mail: [email protected]
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Presbyopia Treatment With PAC Using NAVEX/Uy & Go
Final Fit ablation planning software (NIDEK Co Ltd).
The tenets of the Declaration of Helsinki were followed
in this study.
Patients who underwent LASIK had ophthalmic
evaluations preoperatively and at 1 week, 1 month, 3
months, 6 months, 1 year, and 2 years postoperatively. Epithelial-LASIK (epi-LASIK) patients underwent
ophthalmic evaluations at 4 days, 1 month, 3 months,
6 months, 1 year, and 2 years postoperatively. Evaluations included the measurement of uncorrected visual acuity (UCVA) at near (33 cm) and distance, best
spectacle-corrected visual acuity (BSCVA) at near and
distance, manifest refraction (push plus method), slitlamp examination, intraocular pressure (IOP), corneal
topography and wavefront aberrometry using the OPDScan, corneal thickness, and dilated funduscopy. Postoperatively, dilated funduscopy was performed only
if clinically warranted, and IOP was measured from 3
months onward. Due to significant drop-out rates after 3 months, follow-up data at 3 months will be discussed; however, data for all visits are presented.
Patients were divided into two groups based on their
preoperative refractive error: patients with myopic presbyopia and patients with hyperopic or emmetropic
presbyopia. The myopic presbyopia group comprised
195 (62.1%) eyes of 98 patients and the hyperopicemmetropic presbyopia group comprised 119 (37.9%)
eyes of 60 patients. The hyperopic-emmetropic presbyopia group comprised 59 (18.8%) hyperopic eyes
and 60 (19.1%) emmetropic eyes.
Patients With Myopic Presbyopia. Mean patient age
was 46 years (range: 30 to 65 years). In the myopic
presbyopia group, 26 (26.5%) patients were in their
40s, 40 (41%) patients were in their 50s, 26 (26.5%)
patients were in their 60s, and 6 (6%) patients were
in their 70s. Mean preoperative manifest refraction
spherical equivalent (MRSE) was 3.802.10 diopters
(D) (range: 8.25 to 0.50 D).
Patients With Hyperopic and Emmetropic Presbyopia. Mean patient age was 56 years (range: 37 to
73 years). In the hyperopic-emmetropic presbyopia
group, 1 (1%) patient was in his 40s, 11 (19%) patients
were in their 50s, 25 (42%) patients were in their
60s, 20 (34%) patients were in their 70s, and 3 (4%)
patients were in their 80s. Mean preoperative MRSE
was 1.000.92 D (range: 0.00 to 3.50 D)
FINAL FIT AND PAC SIMULATIONS
All treatment simulations and calculations were performed using the PAC calculator (NIDEK Co Ltd) and
Final Fit software. The PAC calculations were manually entered into the laser and Final Fit shot data were
transferred to the laser via universal serial bus disk.
Journal of Refractive Surgery Volume 25 January (Suppl) 2009
The PAC calculation software requires entry of the
patient’s refraction, age, photopic and mesopic pupil
size, and answers to a preoperative questionnaire assessing the patient’s activities and visual requirements.
Based on these parameters, the laser data entry parameters and optical and transition zones are generated for
the presbyopic treatment. Final Fit software has been
described previously.6 The manifest refraction was adjusted using the nomogram S095-C118-S30 in Final
Fit version 1.13 to determine the laser data entry for
the distance correction. The distance refractive error
and preoperative irregularity were treated using the
optimized path difference custom ablation treatment
(OPDCAT) algorithm with aspheric profile #5 in Final
Fit. The PAC algorithms have been described previously.3,4,7 In all cases, the distance correction was performed prior to PAC treatment in the same session. For
example, a 50-year-old myopic patient with a manifest
refraction of 4.00 0.50 179° with a 3-mm photopic pupil diameter and 6-mm mesopic pupil diameter
with normal daily driving habits, who reads approximately 1 hour a day, occasionally uses the computer,
and participates in a sports once a week would require
the following treatment using PAC and Final Fit:
●
1) OPDCAT ablation of 3.623 0.590 179° using
a 5.0-mm optical zone (OZ) and 8.5-mm transition
zone (TZ) to treat the distance correction;
●
2) 3.00 D using a 6.5-mm OZ and 9.5-mm TZ for
the near add;
●
3) 3.00 D using a 3.5-mm OZ and 4.5-mm TZ to
bring the central cornea to emmetropia;
●
4) 1.00 D using a 4.0-mm OZ and 5.0-mm TZ to
bring the central cornea to emmetropia; and
●
5) Irregularity component using a 5.0-mm OZ and
8.0-mm TZ to treat the pre-existing wavefront aberrations.
An aspheric ablation profile was used for all myopic treatments (steps 1, 3, and 4 above). Hyperopic and
irregular components (steps 2 and 5 above) do not require the selection of a specific profile. In this example,
161.30 µm is the total depth of ablation.
SURGERY
Two hundred sixty-eight eyes underwent LASIK and
46 eyes underwent epi-LASIK. LASIK or epi-LASIK
was performed based on preoperative corneal thickness and residual stromal bed calculations that would
leave 300 µm postoperatively. Patients with adequate
residual stromal tissue or corneas thicker than 450 µm
underwent LASIK. All surgeries were performed by
one surgeon (E.U.).
LASIK. Eyes were prepared for surgery in a sterile
manner. Two drops of topical anesthetic were instilled,
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Presbyopia Treatment With PAC Using NAVEX/Uy & Go
Figure 2. Stability of 195 myopic presbyopic eyes that underwent pseudoaccommodative cornea (PAC) treatment for myopia and presbyopia.
Figure 1. Attempted manifest refractive spherical equivalent (MRSE) 3 to
12 months postoperatively of 195 myopic presbyopic eyes that underwent
pseudoaccommodative cornea (PAC) treatment for myopia and presbyopia.
and a sterile drape was used to isolate the surgical
field. A lid speculum was inserted in the operative eye,
followed by two drops of topical anesthetic. Gentian
violet marks were placed from the midperipheral cornea to the limbus for flap alignment. The Moria M2
keratome (Moria, Antony, France) was used to create a
superior hinged corneal flap using the M2 M90 blade,
LC ring (large cut ring), with the stop at 8 for corneas
with an average preoperative keratometry of 41.00 to
44.50 D. In corneas with an average preoperative keratometry between 44.50 and 45.50 D, the 0 ring with
an 8 stop was used, and in corneas steeper than 45.50
D, the 2 ring with a 7.50 stop was used. The flap was
reflected, and a 200-Hz infrared eye tracker centered on
the visual axis was enabled. Laser ablation was delivered to the corneal stroma centered on the visual axis.
Patients fixated on a red fixation light throughout the
ablation. The flap was repositioned, and the interface
was irrigated with balanced salt solution to remove interface debris. The flap was inspected for adherence
and to verify correct alignment. One drop each of topical fluoroquinolone, topical corticosteroid, and artificial tears was instilled. The patient remained supine
for 1 minute to allow the flap to adhere. Postoperatively, patients were instructed to instill topical fluoroquinolone and corticosteroid drops 4 times daily for
1 week and preservative-free artificial tears as needed.
Epi-LASIK. Two drops of topical anesthetic were instilled in the eye undergoing surgery. A lid speculum
was inserted into the operative eye, and an additional
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two drops of topical anesthetic were instilled. One drop
of balanced salt solution was instilled before applying
the suction ring. The Moria Epi-K was used to create the
epithelial flap. Ring 1 and stop 9 were used in all cases.
The flaps were discarded. A 200-Hz infrared eye tracker
centered on the visual axis was enabled. Laser ablation
was delivered to the corneal stroma centered on the visual axis. Patients fixated on a red fixation light throughout the ablation. After ablation, a soft contact lens was
placed on the cornea. Subsequently, one drop of topical fluoroquinolone, one drop of topical corticosteroid,
and one drop of artificial lubricant were instilled. The
contact lens was removed on postoperative day 4. Postoperatively, patients were instructed to instill topical
fluoroquinolone 4 times a day for 10 days, nonsteroidal
topical drops 4 times daily for 1 week, topical steroids
twice daily for 1 month, and preservative-free artificial
tears as needed for 2 months.
ANALYSIS
The mean, standard deviation, and range of refractive
outcomes; near and far visual acuity; corneal asphericity; and corneal spherical aberration were calculated
using Microsoft Access (Microsoft Corp, Redmond,
Wash). Corneal spherical aberration was calculated at
4, 5, and 6 mm to determine the induced multifocality
using the NIDEK OPD-Station software. Corneal asphericity was measured at 4.40, 5.20, 6.40, and 7.40 mm to
determine the change in corneal shape associated with
the multifocal corneal profile.
RESULTS
MYOPIC PRESBYOPIA
Postoperatively, 96 (49.2%) eyes were available for
follow-up at 3 months, 36 (18.5%) eyes at 6 months,
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Presbyopia Treatment With PAC Using NAVEX/Uy & Go
A
B
Figure 3. A) Distance and B) near uncorrected visual acuity (UCVA) of
195 myopic presbyopic eyes that underwent pseudoaccommodative
cornea (PAC) treatment for myopia and presbyopia. C) Distance UCVA
versus near UCVA at 3 months postoperatively. The red circle denotes
functional vision of 20/30 or better distance UCVA combined with J3 or
better near UCVA.
C
63 (32.3%) eyes at 1 year, and 35 (17.9%) eyes at 2
years. Mean postoperative MRSE was 0.400.77 D
(range: 2.50 to 1.25 D) at 3 months, 0.310.67 D
(range: 2.00 to 0.75 D) at 6 months, 0.860.91 D
(range: 2.25 to 0.75 D) at 1 year, and 0.450.53 D
(range: 1.88 to 0.75 D) at 2 years. Figure 1 plots
the predictability at all follow-up evaluations. A trend
toward undercorrection was noted for corrections of
MRSE 6.00 D (see Fig 1). Stability of the myopic
presbyopic treatments is plotted in Figure 2. Figure 3
plots the distance and near UCVA and the number of
patients who achieved “functional vision,” defined as
20/30 or better distance UCVA combined with J3 or
better near UCVA. Retreatments were performed on 4
(2.1%) eyes at 3 months or later.
HYPEROPIC AND EMMETROPIC PRESBYOPIA
Postoperatively, 46 (38.7%) eyes were available for
follow-up at 3 months, 30 (25.2%) eyes at 6 months,
Journal of Refractive Surgery Volume 25 January (Suppl) 2009
43 (36.1%) eyes at 1 year, and 19 (15.9%) eyes at 2
years. Mean postoperative MRSE was 0.150.62 D
(range: 1.25 to 1.38 D) at 3 months, 0.030.63 D
(range: 1.50 to 1.25D ) at 6 months, 0.500.21 D
(range: 0.88 to 0.25 D) at 1 year, and 0.060.74 D
(range: 1.00 to 1.38D) at 2 years. Figure 4 plots
the predictability at all follow-up evaluations. Figure 5
plots the stability of the hyperopic and emmetropic
presbyopic treatments. Figure 6 plots the distance
and near UCVA and the number of patients who
achieved “functional vision.” Retreatments were
performed on 1 (0.8%) hyperopic eye and 1 (0.8%)
emmetropic eye.
CORNEAL SPHERICAL ABERRATIONS AND CORNEAL
ASPHERICITY
Figure 7 plots the corneal spherical aberrations at
various pupil diameters 3 months postoperatively.
Figure 8 plots the corneal asphericity at 3 months
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Presbyopia Treatment With PAC Using NAVEX/Uy & Go
Figure 5. Stability of 119 hyperopic and emmetropic presbyopic eyes
that underwent pseudoaccommodative corneal (PAC) treatment.
Figure 4. Attempted manifest refractive spherical equivalent (MRSE) 3
to 12 months postoperatively of 119 eyes that underwent hyperopic or
emmetropic presbyopic pseudoaccommodative cornea (PAC) treatment.
postoperatively. All corneas became increasingly
steeper from center to periphery (see Fig 8). There
was an induction of corneal spherical aberration of
0.312 µm at 6 mm for patients with myopic presbyopia and 0.016 µm for patients with hyperopic presbyopia (see Fig 7).
DISCUSSION
In this study of the treatment for presbyopia using an
excimer laser, treatment with PAC software combined
with OPDCAT was predictable (see Figs 1 and 4) and
allowed functional vision (see Figs 3 and 6). Three
months postoperatively, the MRSE was 0.40 D in myopic presbyopes and 0.15 D in hyperopic presbyopes.
The outcomes in this study are similar to or exceed
those reported for previous trials regarding LASIK for
presbyopia.5,8 A recent study also using the distancedominant central treatment in a similar range of
patients with hyperopic presbyopia but having a much
smaller sample size (N=44 eyes) than our study (N=119
eyes) reported an MRSE of 0.42 D.5 In an investigation of an earlier version of the PAC technique without wavefront treatment, the majority of patients with
hyperopia and myopia achieved functional vision as
defined in this study.8
This study confirms that PAC combined with OPDCAT is a viable alternative to other corneal treatments
such as monovision or conductive keratoplasty for
presbyopia.
Within 3 months postoperatively, 83.5% of patients
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with myopia and 87% of patients with hyperopia and
emmetropia had functional vision for daily activities.
Further, the overall retreatment rate was less than 2%,
which is appreciably lower than 7% recently reported
for 82 LASIK patients with myopia who chose monovision.9 Although older age has been associated with an
increased trend toward retreatments, the retreatment
rate in this study remained low. Compared with “light
touch” conductive keratoplasty, which may still result
in some loss of effect over time, the PAC procedure is
relatively stable (see Figs 2 and 5).10
Presbyopic intraocular lenses (IOLs) are another
alternative to treating patients with presbyopia. However, explantation rates remain relatively high (7.3%),11
and greater inherent risks are present with intraocular
surgery compared with corneal surgery. In addition,
there have been reports of decreased near contrast sensitivity associated with multifocal IOLs.12
This study used an aspheric ablation algorithm
(OPDCAT) for all myopic ablations, whether to correct
distance refractive error or to create the near add. The
use of aspheric algorithms is beneficial to patient satisfaction. Hori-Komai et al13 compared conventional
LASIK with aspheric LASIK using profile #5 with the
NAVEX platform and reported a statistically significant
difference favoring the aspheric group in postoperative
effective optical zone and contrast sensitivity.
In this study, an average induction of 0.164 µm of
spherical aberration (at 6 mm) was noted in all eyes,
with the myopic eyes showing greater induction of
spherical aberration (0.312 µm) (see Fig 7). Peripherally, the cornea became increasingly prolate for hyperopic treatments and less oblate in myopic treatments
(see Fig 8). The increasing corneal curvature in the
periphery was likely due to the delivery of multiple
ablations with different treatment zones that were dejournalofrefractivesurgery.com
Presbyopia Treatment With PAC Using NAVEX/Uy & Go
A
B
Figure 6. A) Distance and B) near uncorrected visual acuity (UCVA) of
119 hyperopic and emmetropic presbyopic eyes that underwent pseudoaccommodative cornea (PAC) treatment. C) Distance UCVA versus
near UCVA at 3 months postoperatively. The red circle denotes functional
vision of 20/30 or better distance UCVA combined with J3 or better near
UCVA.
C
livered to the cornea. In our experience, this multifocal cornea results in an emmetropic center and myopic
periphery for patients with hyperopia and myopia, the
hallmarks of positive spherical aberration (Fig 9).
Past investigations of presbyopic LASIK studies have
reported success for patients with myopic or hyperopic
presbyopia but not both.4,5 El Danasoury et al4 report
success only in patients with myopia, whereas Pinelli
et al5 report success with hyperopia treatment only.
Our study found that presbyopia treatments were successful regardless of preoperative refractive status. The
difference in outcomes may be attributable to the use of
an entirely different ablation architecture from a different laser model (Technolas 217z; Bausch & Lomb Inc,
Rochester, NY)5 or to the use of conventional ablation
algorithms rather than the incorporation of OPDCAT
in the treatments.4 This study incorporated a number
of refinements to the original PAC procedure,3,4 including the use of an aspheric profile for all myopia treatJournal of Refractive Surgery Volume 25 January (Suppl) 2009
ments (ie, OPDCAT) and the treatment of irregularities
as detected by Final Fit.
In our experience, candidates for presbyopic excimer
laser treatments require thorough preoperative evaluation of their near and distance vision requirements along
with an assessment of their lifestyle. Patients must have
realistic expectations that include the fact that vision
may be compromised yet functional enough to reduce
or eliminate dependence on spectacles postoperatively. In addition, the effects and implications of cataract
progression must be thoroughly explained.
Drawbacks of this study include the lack of control data such as eyes that were treated for distance
refractive error only. Furthermore, a significant number of patients were lost to follow-up 3 months after
surgery. In our experience, the majority of satisfied
patients tend not to return for follow-up. Thirty-five
myopic presbyopic eyes and 19 hyperopic presbyopic
eyes were available for follow-up at 2 years postopCommercially Sponsored Section
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Presbyopia Treatment With PAC Using NAVEX/Uy & Go
Figure 7. Corneal spherical aberration (SA)
pre- and postoperatively at various pupil
diameters of A) myopic presbyopic eyes
and B) hyperopic or emmetropic presbyopic
eyes that underwent treatment for distance
refractive error and presbyopia.
Figure 8. Corneal asphericity (Q value)
pre- and postoperatively at various corneal
diameters of A) myopic presbyopic eyes
and B) hyperopic or emmetropic presbyopic
eyes that underwent treatment for distance
refractive error and presbyopia.
eratively. Thirty-four (97%) myopic presbyopic eyes
and 18 (95%) hyperopic presbyopic eyes had 20/30
or better distance UCVA. Thirty-three (94%) myopic
presbyopic eyes and 12 (63%) hyperopic presbyopic
eyes read J3 or better without spectacle correction.
Some patients retained functional vision 2 years postoperatively, which suggests the stability of this procedure with an adequate sample size.
Pseudoaccommodative cornea treatments that incorporate OPDCAT to create a center-distance or periphS154
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eral-near multifocal cornea are successful for the treatment of myopia up to 8.25 D MRSE and hyperopia
up to 3.50 D MSRE in patients with presbyopia. However, long-term outcomes with larger sample sizes are
required to determine the stability of this procedure.
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journalofrefractivesurgery.com
Presbyopia Treatment With PAC Using NAVEX/Uy & Go
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