View
6
Download
0
Category
Preview:
Citation preview
Refractive Surgery for High Ametropias
When LASIK is not enough
Γεώργιος ΠασλόποσλοςΔντής Οφθαλμολογικής ΝΙΜΤΣ
Georgios Pavlopoulos
Dept of Ophthalmology
Shared Army Fund Hospital of Athens
Refractive Surgery for High AmetropiasRefractive Surgery for High Ametropias
PRK or LASIK in High ametropia
Haze (PRK)
Regression (PRK & LASIK)
in high myopes (>7.0 D), regression was observed
despite single or double application of MMC (PRK)
regression of -0.25 D per year
High order aberrations (PRK & LASIK)
Iatrogenic Ectasia (LASIK)
Iatrogenic Ectasia - Risk Factors
Age (<30 y)
MRSE (> - 8.00 D)
Preoperative Corneal Thickness (< 510 μm ??)
Residual bed thickness (<300 μm ??)
Abnormal Preoperative Corneal Topography
Increased high order aberrations (especially coma)
Decreased cornea tensile strength (ORA, Corvis, Brillouin)
Refractive instability with decreased BSCVA
Family history of keratoconus
Chronic trauma (eye rubbing)
Iatrogenic Ectasia
Refractive Surgery for High Ametropias
Available options
LASIK + CXL (LASIK Xtra or LASIK with Rapid CXL)
Refractive Lens Exchange (Refractive Lensectomy)
Phakic Intraocular Lenses
Angle-supported Anterior Chamber pIOLs
Iris-Fixated pIOLs
Posterior Chamber pIOLs
Rapid CXL during LASIK
Lasik Xtra (Avedro) or VibeX riboflavin 0.25% for 1 min 30 mW/cm2 for 75 sec
Rapid CXL during LASIK (IROC) riboflavin 0.5% for 2 min 9 mW/cm2 for 5 min
LASIK+CXL is safe but efficacy has not been demonstrated Be on the outlook for longterm changes because CXL may induce
remodeling
Refractive Surgery for High Ametropias
Age limits
Refractive Lens Exchange
Accommodation - Hyperopes over 45 y (hyperopia > +3D)
Risk of Retinal Detachment - Myopes - Elderly patients
with early cataract
Phakic Intraocular Lenses
over 45 y ? – Glaucoma (PEX), Presbyopia, Cataract
Refractive Lens Exchange - Additional Considerations
Discuss with the patient
Choice of IOL
Monofocal,
Multifocal,
Mix and match,
Toric
IOL calculation (Optical Biometry)
Bioptics
Complications
Refractive Lens Exchange - Complications
Complications of cataract surgery
loss of accommodation
missed target refraction
posterior capsular opacification
cystoid macular edema
retinal detachment
secondary glaucoma
endophthalmitis
Refractive Lens Exchange - Retinal Detachment
Retinal detachment
Natural incidence of RD in high myopia without surgical
intervention is 0.68% per year for myopia > -10.00 D.
The reported incidence of RD after RLE, (5-8 y f/u)
ranges from 0.2% - 1.2% per year
Refractive Lens Exchange - Retinal Detachment
YAG capsulotomy & Retinal detachment
Each millimeter increase in axial length raises the risk
of RD after Nd-YAG capsulotomy by a factor of 1.5
The reported rate of YAG capsulotomy after RLE
ranges from 61% to 78%
50% of the RDs that occur after YAG capsulotomy
result from new lesions
Refractive Lens Exchange - Retinal Detachment
Prophylactic treatment to prevent RD
Fundus exam with scleral depression (VR specialist)
Microincisional techniques (stable chamber)
Prevent posterior capsule opacification
Capsulorhexis (round & centered, should completely
overly the edge of the IOL optic)
Meticulous cortical clean-up
IOL with a sharp posterior edge
Phakic IOLs – Available Models
Patient selection – Phakic IOLs Power Range
Phakic IOLs
Phakic IOLs Patient selection – Anatomy of eye
Anterior Chamber Depth (Endothelial Damage)
Angle-supported Anterior Chamber pIOLs – 3.2 mm
Iris-Fixated pIOLs – 3.0 mm (EMS) or 3.2 mm (FDA)
Posterior Chamber pIOLs – 2.8 mm or 3.0 (FDA)
Phakic IOLs Patient selection – Anatomy of eye
AC Interior Diameter
Size AC diameter with AS-
OCT, UBM, Scheimpflug camera, forget
white to white
Angle-supported AC pIOLs
AC is oval (in 75% of cases vertical axis
is larger)
IOL must fit the larger diameter
(Length & Axis)
Iris-Fixated pIOLs > 11.5 mm
Posterior Chamber pIOLs
Important for the vaulting of ICL
Phakic IOLs Patient selection – Anatomy of eye
Distance of Phakic IOL to the Endothelium
AS-OCT simulation of Phakic IOL position
Peripheral edge – 1.5 mm
At center – 2.0 mm
Phakic IOLs Patient selection – Anatomy of eye
The crystalline lens rise (Iris-fixated Phakic IOLs)
Distance between the anterior surface of the crystalline lens and the
horizontal line between the two angle recesses
The anterior pole of the crystalline lens moves forward by 20 μm / year
The crystalline lens rise for Iris-fixated Phakic IOLs > 600 μm
If IOL sits too close to the iris, it can cause pigmentary dispersion from iris
Phakic IOLs Patient selection – Anatomy of eye
The vault (PC Phakic IOLs)
Distance between back of pIOL &
the anterior crystalline lens pole
Ideal vault is between 1.0 and 1.5
corneal thicknesses (500-700 μm)
Vault
Phakic IOLs Patient selection – Anatomy of eye
Vaulting depends on the diameter of the PC pIOL
Diameter of pIOL too long Lens vault excessive
if>750μ Risk of Angle closure Glaucoma, Pigment dispersion
Diameter of pIOL too short Lens vault less
if<250μ Risk of Anterior capsular cataract
Phakic IOLs Patient selection – Anatomy of eye
The Endothelial Cell Count
Minimum endothelial cell density (ECD) per age group at time of
implantation (FDA) is the upper 90% confidence interval of the
average cell loss (2.31%) for eyes with ACDs of 3.2 mm or greater
cell count >3,000 cells/mm2 if patient is younger than 30 y
Phakic IOLs Patient selection – Anatomy of eye
The Pupil
Mesopic pupil size < size of pIOL optic + 1.00 mm:
Angle-supported AC pIOLs < 7.0 mm
Iris-Fixated pIOLs < 6.5 – 7.0mm
Posterior Chamber pIOLs < 7.0 mm
Eccentric pupils Iris-Fixated pIOLs
Phakic IOLs - Complications
Complications
intra & postoperative intraocular surgery complications
chronic iridocyclitis
iris atrophy, pupil ovalization
lens dislocation, rotation
secondary glaucoma
(pupillary block, pigment dispersion),
cataract formation
endothelial cell loss
halos and glare
Phakic IOLs - Endothelial cell loss
Possible causes of endothelial cell loss
Intraoperative trauma
Rubbing of eyes postoperatively
Subclinical inflammation (laser flare cell meter)
Progressive loss of endothelial cell loss
Rate of ECD slowed down substantially from 1 to 2 years
Central endothelial cell counting may miss early ECD
Peripheral endothelial cell counting may be able to detect
progressive loss earlier
Phakic IOLs - Endothelial cell loss
Natural cell loss is in the range of 0.5% per year
AcrySof Cachet
4.8 ± 8 % at 1 year (Kohnen, Knorz, Colin, Alio et al, 190 eyes)
?? 0.4% at 6 mo to 1.1% at 3 years (Knorz et al, 360 eyes) ??
3.7% at 6 mo, 5.1% at 1 year, 7.4% at 2 years (Doors et al, 117 eyes)
Kelman Duet
5.4% ± 12 at 1 year (Alio et al, 169 eyes)
Iris-Fixated pIOLs
0.7% at 3 years (Budo et al, 518 eyes)
4.8% at 3 years (Stulting et al, 684 eyes)
Posterior Chamber pIOLs
At 3 years, 6.5% (Lackner et al, 76 eyes)
At 3 years, 8.4% (Edelhauser et al, 212 eyes)
At 5 years, 7.7% (Alfonso et al, 188 eyes)
Phakic IOLs - Cataract
Anterior subcapsular opacities
Became clinically significant cataract surgery in 27.9%
Possible causes of Cataract formation
Intraoperative surgical trauma
Surgeon learning curve
Postoperative inflammation
Lower ICL vault values <200μm (lower ICL size)
Mechanical interaction or trauma on the anterior capsule
Disturbances in aqueous flow (metabolic disturbances)
Patient-dependent factors (Age and High myopia)
Phakic IOLs - Cataract
Angle-supported AC pIOLs
AcrySof Cachet, 1.9% at 3 years (Alcon data, 360 eyes)
Kelman Duet, 0% at 1 year (Alio et al, 169 eyes)
Iris-Fixated pIOLs
2.40% at 3 years (Budo et al, 518 eyes)
Posterior Chamber pIOLs
1.3% at 3 years (Alfonso et al, 964 eyes)
5.9% at 5 years (Sanders et al, 526 eyes)
6-7% at 7+ years (FDA)
1-2% progress to clinically significant cataract (FDA)
Phakic IOLs - Advantages
Advantages
Preservation of corneal sphericity
lower optical aberrations
improved contrast sensitivity
Lower enhancement rates
Can correct any ametropia
Bioptics to fine-tune results
Ability to remove or exchange the lens
Phakic IOLs - Conclusions
Conclusions
No Phakic IOL that fits all eyes
Very important to evaluate internal dimensions with AS-
OCT, UBM or Scheimpflug camera
Strict follow up (complications, e.g. cataract)
Yearly endothelial check up
There is no absolutely safe Phakic IOL
Discuss vision-threatening complications - Informed consent
If developed cataract is removed add RLE complications
Recommended