Long-term results of Phakic Refractive Lens (PRL

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Long-term results of Phakic Refractive Lens
(PRL) implantation in high myopic eyes. Ioannis
G. Pallikaris1, 2, MD, PhD, Maria I.
Kalyvianaki1, MD, PhD, Dimitra M. Portaliou, MD,
Sophia I. Panagopoulou1, PhD. 1University of
Crete, Medical School, Vardinoyannion Eye
Institute of Crete, Greece. 2University Hospital
of Heraklion, Department of Ophthalmology, Crete,
Greece.
The authors have no financial or proprietary
interest in any materials or methods
described herein
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Abstract Purpose To evaluate the long-term
efficacy, predictability and safety of phakic
refractive lens (PRL, Carl Zeiss Meditec)
implantation in high myopic eyes. Setting
Department of Ophthalmology, Medical School,
University of Crete, Crete, Greece. Methods 136
myopic eyes of 78 patients were treated for high
myopia with the implantation of the silicone
phakic refractive lens (PRL) in the posterior
chamber. Mean patients age was 28.596.13years
(range 18 to 44 years). Manifest refraction in
spherical equivalent (MR), uncorrected (UCVA),
best-corrected (BCVA) visual acuity (decimal
scale), intraocular pressure, possible
complications and subjective symptoms were
evaluated. Results Mean follow-up was 3.82
1.93 years (range 6 months to 7 years). Two years
after the treatment (N62) there was a
statistically significant reduction in the MR
pre-PRL -14.00D4.18D (-26.00D to -5.00D) to
-0.16D0.43D (-2.25D to 1.00D) (plt0.001). 75
(55) and 109 eyes (80) were within 0.50 D and
1.00 D of target refraction respectively. Mean
UCVA significantly (plt0.001) improved pre-PRL
counting fingers preoperatively in all eyes to
0.790.27 (0.2 to 1.2). Mean BCVA also improved
from 0.710.24 (0.10 to 1.00) to 0.870.27 (0.40
to 1.20) (plt0.001). Up to seven years
postoperatively no treated eyes presented any
signs of cataract. Conclusion Long-term results
showed that PRL implantation was an effective
and safe method for treating high myopia.
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Introduction
The Phakic Refractive Lens (PRL) is a
posterior chamber lens developed by Medennium
Inc. It is made of silicone with high refractive
index (1, 46), which allows its ultra thin
design. PRL is not supported in the sulcus
angle, but it floats in the posterior chamber
over the crystalline lens, due to its hydrophobic
material (Figures 1a,b). Its cent ration is
achieved by its self-centering design. The
one-and two-year clinical results of PRL
implanted eyes suggest that it is efficient and
predictable for the treatment of high myopia and
hyperopia1-5. However, longer follow-up is
mandatory, in order to evaluate its safety and
stability. The purpose of our study was to
evaluate the long-term efficacy, predictability
and safety of phakic refractive lens (PRL, Carl
Zeiss Meditec) implantation in high myopic eyes.
Figure 1a
Figure 1b
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Materials and methods 136 myopic eyes of 78
patients were treated with PRL implantation by
the same surgeon (IGP). Mean patients age was
28.596.13years (range 18 to 44
years). Preoperative evaluation included
manifest refraction in spherical equivalent (MR),
uncorrected (UCVA), best-corrected (BCVA) visual
acuity (decimal scale), intraocular pressure,
slit lamp microscopy, pupil size measurement
under scotopic conditions, white to white corneal
diameter measurement with the use of a caliper,
dilated fundoscopy and A-scan ultrasonography
(Axis-II, Quantel Medical ). PRLs were inserted
with the use of special forceps. At the end of
the procedure a surgical iridectomy was performed
with the use of a vitreotome in 72 eyes, while
two YAG-laser iridotomies were performed 1 week
before the procedure in 64 eyes. Mean follow-up
was 3.82 1.93 years (range 6 months to 7 years).
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ResultsEfficacy

• Mean UCVA significantly improved from
  counting fingers preoperatively in all
  eyes to 0.79 (N62, decimal scale) at the 2 year
  follow up examination

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ResultsSafety
Compared to the preoperative value, 78 of eyes
(106) gained 1 to 4 lines of BCVA
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ResultsStability
Refractive results remained stable during the
six-year follow-up
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ResultsPredictability
At two years 34 (55) and 50 eyes (80) were
within 0.50 D and 1.00 D of target refraction
respectively.
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Complications

• During surgical iridectomy with the probe of a
  vitreotome, 3 eyes experienced damage of the
  anterior capsule of the crystalline lens.
• In fourteen eyes (10) a statistically
  significant increase in IOP was found during the
  1st month post-op. IOP returned to preoperative
  levels at three months (6 patients were
  corticosteroid responders).
• Rotation of the PRL was noticed in many cases
  with no consequences.
• One eye had pigment dispersion, high IOP and PRL
  extraction 3 years postop due to reverse PRL
  implantation.
• There was one case of PRL decentration and PRL
  extraction 3 years postop (Figure 2) .
• No PRL was lost in the vitreous
• No eye presented cataract during the 7-year
  follow-up

Figure 2
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Complications
Figure 3 Slitlamp photograph of patient 3 months
after PRL implantation shows focal opacity behind
iridectomy because of damage to the anterior
capsule. Opacification remained focal behind the
iridectomy and did not progress to cataract in
the visual axis
Figure 4 (Pallikaris) Slitlamp photograph shows
anterior subcapsular opacification 1 year
post-PRL implantation. No progression or loss of
BCVA was noted.
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Discussion
Long-term results suggest that PRL is an
effective, predictable, stable and safe method
for the treatment of high myopia. However,
further follow-up and additional patients must be
reviewed to draw final conclusions about the
efficacy and safety of this lens. Moreover,
preoperative and postoperative endothelial cell
count would be indicative of the percentage of
endothelial cell loss after PRL implantation.
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References

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