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