NEW REFRACTIVE TECHNOLOGY
| Phakic and Presbyopic IOLs—David R. Hardten, MD, Adjunct Associate Professor of Ophthalmology, University
of Minnesota School of Medicine, Minneapolis, and Director of Refractive Surgery, Minnesota Eye Consultants
|
Phakic Intraocular Lenses (IOLs)
| Why choose phakic IOL? has role in management of higher refractive errors, especially in prepresbyopic patient; in
younger patient, accommodation retained; removable; predictable refractive error; for loss of best spectacle-corrected visual
acuity (BSCVA) from irregular astigmatism, phakic IOLs safer than laser in situ keratomileusis (LASIK), especially
for -10 diopters (D)
|
| Verisyse IOL: 95% of patients had spherical equivalent within 1 D of emmetropia or target; 92% of patients have 20/40 or
better uncorrected visual acuity in clinical trials; loss of ≥2 Snellen lines of BCVA (6%); 49% gain lines of acuity (provides
extra magnification without distortion or irregular astigmatism); patient satisfaction high; endothelial cell loss—no clinically
significant changes; small loss not problem in properly identified candidates; if implant close to endothelium or patients
rub eyes and endothelium touches implant, patients can lose endothelial cells; in typical patient with deep anterior
chamber and well-positioned implant, endothelial cell loss not problem
|
| Visian implantable collamer lens (ICL): results comparable to Verisyse; in study, normal retinas and preoperative
BSCVA 20/20 or better; at 3 yr postoperatively, 95% 20/40 or better (≈60% 20/20 or better)
|
| General use of phakic IOLs: prepresbyopic myopia (-8 to -10 D); in thin cornea, -6 D (available to -5 D)
|
| Verisyse and refractive lens exchange (RLE): retain accommodation; less risk for retinal detachment with phakic implant
than RLE, especially in highly myopic patients
|
| Verisyse enclavation: iridotomy or iridectomy critical to prevent angle closure or pupillary block; paracentesis at 10 and 2
o’clock to gain access to midperipheral iris; incision relatively short; disadvantage of design (6.0-6.5-mm incision because
optic 6 mm and edges thicker than center of optic); position changes depending on anterior chamber (AC) depth (memorize
AC depth); technique—stabilize implant with, eg, Budo forceps; push tuck of iris up into polymethylmethacrylate
(PMMA) claws that hold iris in midperipheral position; safe to dilate eye postoperatively; center implant on pupil; speaker
prefers corneoscleral wound (others prefer clear corneal wound)
|
| Visian ICL insertion: most difficult aspect of procedure loading lens into injector; once injected, stay in periphery, then
tuck footplates under iris in midperiphery; tuck 4 haptics to make sure implant well-centered
|
| Postoperative care: antibiotic; steroid; nonsteroidal anti-inflammatory drug; follow-up at 1 day, 1 wk, and 1 mo; wait ≈1
mo for second eye (especially with Verisyse) because of larger incision and astigmatic changes over first month; with Visian,
slightly quicker recovery (many patients ready for second eye by 1 to 2 wk); annual endothelial cell counts recommended
by Food and Drug Administration (FDA)
|
| More about RLE: in high refractive correction, especially hyperopic correction, advantage of implant over LASIK is preservation
of corneal asphericity; speaker uses clear lensectomy or RLE mostly in high hyperopes (also, eg, patient 65 yr of
age with -11 D correction); options—monofocal, multifocal, or accommodating IOLs (eg, Array multifocal IOL)
|
Presbyopic IOLs
| ReStor IOL: apodized diffractive technology (multifocality throughout implant); central 3.6 mm of optic facilitates near
and distance vision; diffractive steps reduce in size toward periphery; because of less diffraction toward periphery, decreased
glare and halos; unlike Array lens, does not depend on pupil size (4- or 5-mm pupil not required for near effect);
measure pupil size in dim and bright light; available as one-piece design (soon, 3-piece may allow sulcus placement in
patients lacking intact anterior capsule rim)
|
| ReZoom IOL: specifications—3-piece implant; hydrophobic acrylic; PMMA capsule-fit haptics; 13-mm overall haptic
length; correction ≥6 D; Balanced View Optics technology—center of implant distance-dominant zone; in brighter
light, less near effect; in bright light (eg, daytime driving) with smaller pupil, more distance effect; with ReStor lens, with
smaller pupil, distance and near effect; in bright-light reading, reduced near effect (especially with smaller pupil); midperipheral
portion provides aspheric transition to near-dominant zone; toward periphery, near-dominant effect; small section
in periphery distance dominant
|
| Tecnis multifocal IOL: aspheric design; may reduce nighttime glare; most popular multifocal IOL in Europe; not available
in United States
|
| Crystalens IOL (Eyeonics): specifications—silicone plate haptic implant; along edges, polyamide loops or haptics;
more flexible (hinge allows movement); 4.5-mm optic diameter; requires intact capsule and well-rounded anterior capsule
to achieve good centration; 20/25 or better result at 1 yr—for distance vision, achieved in 92% of patients; intermediate
range (98%); near (73%); not as near-dominant as ReZoom or ReStor implant; less glare and halo complaints for
distance with Crystalens, compared to ReZoom and ReStor
|
| Spectacle dependence: 70% to 75% of patients spectacle-independent almost all the time (26% do not use spectacles at
all; rate slightly higher in ReStor and ReZoom trials, but range similar); counseling patients—implants help to reduce
spectacle dependence; presbyopic implants provide more spectacle independence than monofocal distance implant in
both eyes; patient may still need glasses occasionally; may need to “fine tune” later with LASIK, photorefractive keratoplasty
(PRK), piggy-back IOL, or IOL exchange
|
| Best candidates: patients with realistic expectations; ideal candidate 85-yr-old patient 20/100 BCVA bilaterally with cataracts;
low hyperope with cataract ideal because he or she used to poor focus (myopes used to removing glasses to see up
close); IOL calculations more difficult in high hyperope; across the rule (ATR) astigmatism ideal; patient seeking better
distance, middle, and near vision, and willing to accept some spectacle use
|
| Axial length determinations: immersion ultrasonography—Prager Shell has single-use tubing to limit cross-contamination;
autoclavable designs; IOLMaster (Zeiss)—good approach (except in patients with dense posterior subcapsular cataracts
or extremely high axial lengths)
|
 | Careful wound construction: 3.0- to 3.5-mm incision; can be sutured if needed; speaker prefers 3.5-mm incision at beginning
of surgery to allow more wound leak (unless patient has difficult cataract); important that lens stay posterior in
capsular bag; shallow chamber or wound leak problem with this implant
|
| Sizing of capsulorrhexis: current recommendation 6-mm marker on cornea (5.0-5.5-mm capsulorrhexis); with 6-mm
marker, capsulorrhexis barely overlaps anterior edge of regular IOL; important that IOL well-centered and capsulorrhexis
round; more critical in ReStor than ReZoom because of haptic design
|
| Insertion of lens: Crystalens—use STAAR Indigo or Collamer injector; insert into capsular bag inferiorly; tuck one of
haptics with inserter, then put trailing haptic into capsular bag; inflate to physiologic intraocular pressure (IOP); place
suture; bimanual irrigation and aspiration (I&A) to remove viscoelastic (avoids excessive shallowing of chamber);
paracentesis at 12 and 6 o’clock avoids disturbing main wound; ReZoom and ReStor—injection no different than
with regular monofocal implants
|
| General comparison of IOLs
|
| Style: ReZoom—3-piece acrylic; ReStor—1- and 3-piece acrylic; Crystalens—3-piece silicone
|
| Haptics: ReZoom—standard; Crystalens—haptics on plate lens
|
| Optics: ReZoom—zonal progressive; ReStor—apodized diffractive; Crystalens—potential for movement; multifocality
|
| Capsulotomy: ReZoom or ReStor—typical yttrium-aluminum-garnet (YAG) laser procedure; Crystalens—if capsulotomy
extends past edges of optic, problem of migration of vitreous into posterior or anterior chamber; some patients develop
Z syndrome (contraction of capsule in periphery that pushes hinge up anteriorly; perform YAG capsulotomy that
extends along hinge to reposition; reduces cylinder from tilting of optic in eye)
|
| Dominant focus: ReZoom—intermediate vision; reasonable near vision (not as good as with ReStor); Crystalens—
distance and intermediate vision
|
| Micromonovision: ReZoom—speaker uses +0.25 in distance eye to reduce halo effect; -0.25 in near eye to augment near
vision; ReStor—+0.50 in distance eye; also gives good intermediate vision; plano in near eye; Crystalens—plano in
distance eye; -0.75 to -1.0 in near eye
|
| Pupil size: ReZoom—if patient does not dilate well in medium light, not as good near vision; ReStor—advantage of
near effect in small-pupil patient; if pupil too small, great distance and near vision even with monofocal implant if biggest
pupil gets is 1.5 to 2.0 mm; Crystalens—minimal pupil-size dependence, except for fact that optic 4.5 mm; medium-to-large
sized pupils may have glare or halo at night (use brimonidine [Alphagan] or pilocarpine)
|
| Effect of medication: ReZoom and Crystalens—night halo effects reduced with Alphagan or pilocarpine; ReStor—
less effect on night-vision complaints
|
| More about patient selection: is patient willing to bear extra cost, time, and work required? interested in reducing dependence
on near glasses after cataract surgery? willing to tolerate increase in glare or halo for effect? willing to accept issues
with extra precision? (may need LASIK or PRK or glasses occasionally); find out whether patient prefers distance,
intermediate, or near bias
|
| Regions of vision: far distance; distance (20-100 ft); midrange; intermediate; near (12-16 in)
|
| The Crystalens in Clinical Practice —D. Michael Colvard, MD, Assistant Clinical Professor of Ophthalmology,
Keck School of Medicine at University of Southern California, Los Angeles
|
| Comparison of visual outcomes: monofocal, multifocal IOLs, and Crystalens; comparison of uncorrected distance and near
acuity, relative spectacle independence, and frequency of night vision complaints; in all studies, uncorrected distance acuity
excellent; near vision—standard monofocal lens has excellent near vision (Jaeger acuity J3 or better in about one third of
patients); Array lens (≈91% J3 or better); ReStor lens (≈98% J3 or better without correction); relative spectacle
independence—rate similar for 3 types of lenses; night vision and quality of vision in general—increased problems
with multifocal lenses; ReStor (≈10% of patients have significant night-vision problems; decreased visual quality associated
with multifocality); Crystalens (in speaker’s experience, none explanted because of problems with night vision or quality of
vision)
|
| Indications for Crystalens in clinical practice: clear lens extraction reserved for hyperopes >45 yr of age; >3 D correction;
contact lens intolerance; patient not excellent LASIK candidate, yet significant hyperopia; early lens opacification;
early cataracts in patients who are not good LASIK candidates; myopes and hyperopes >55 yr of age with >1.5-D correction
|
| Best candidates: choosing first patient—best patients have functionally significant cataract (vision and best-corrected
acuity already diminished); with experience, hyperopes >55 yr of age (Crystalens good alternative to LASIK);
advantages—patients comfortable and heal quickly; rapid optical stabilization; dry eye symptoms not exacerbated; generally,
LASIK in patients >55 yr of age difficult (many problems associated with operating on cornea); quality of vision
usually improved; contrast sensitivity improved by implanting or removing lens that has aging changes; low, moderate,
and high hyperopes treated with equal success; lens provides what patients >55 yr of age looking for (full range of visual
function, ie, distance, intermediate, and near)
|
| Poor candidates: -3-D myope who likes to remove glasses to read (patients difficult to please with Crystalens); for same
reason, successful monovision patients not good candidates
|
| More advantages: Crystalens gives full range of visual function; speaker has not had patient unhappy with quality of vision;
option in functional cataract patient interested in presbyopic correction; very little downside; spectacle independence
extremely good
|
| What patients can expect from Crystalens: because of 4-D correction, ReStor lens gives better near vision and more
sustainable vision (Crystalens 1.5- or 2-D correction); to read for prolonged period, patients need in reserve twice as
much correction needed for shorter period (patient who has Crystalens, can read J3 on reading card, but cannot read
novel); many patients use reading glasses or 1.5-D over-the-counter readers for small print or to read in less-than-optimal
lighting; quality of vision in normal activities extremely good; patients can shop without glasses; patients able to read
computer screen, restaurant menu, golf card, and magazine with high-quality print; newspaper more difficult (particularly
in low light)
|
| Disadvantages: accommodative effect takes time to develop; patients see better at 2 mo than at 2 wk (better at 4 mo than at
2 mo; important that patient understands this early on); accommodative effect <5 D
|
| Implantation technique: case—remove all cortex (retained cortex can result in asymmetric contractual forces and distortion
of lens); lens has double hinge; use scleral incision (≈3.5 mm; large corneal incision may leak); speaker uses Lester
or Sinskey hook at end to make sure proximal haptic under capsular bag; if anterior chamber shallows during early postoperative
period, lens will vault forward with myopic result (need suture); bimanual system used to remove viscoelastic;
hydrate side port and primary incision while chamber maintainer working; in this way, lens never comes forward and incision
secure
|
Educational Objectives
| The goal of this program is to educate the listener about new refractive technology. After hearing and assimilating this program,
the clinician will be better able to:
|
| 1. Describe the role of phakic intraocular lenses (IOLs) in clinical practice.
|
| 2. Compare technical features of selected presbyopic IOLs.
|
| 3. Identify candidates for presbyopic IOL implantation.
|
| 4. Recognize advantages and disadvantages of presbyopic IOLs compared to phakic IOLs.
|
| 5. Describe potential indications for the Crystalens IOL.
|
Discussed on This Program
Brimonidine tartrate [Alphagan, Alphagan P]
Pilocarpine HCl (several formulations and trade names)
Suggested Reading
Alio JL et al: Near vision restoration with refractive lens exchange and pseudoaccomodating and multifocal refractive and
diffractive intraocular lenses: comparative clinical study. J Cataract Refract Surg 30:2494, 2004; Alio JL et al: Retinal
image quality after microincision intraocular lens implantation. J Cataract Refract Surg 31:1557, 2005; Alio JL, Mulet
ME: Presbyopia correction with an anterior chamber phakic multifocal intraocular lens. Ophthalmology 112:1368, 2005;
Cazal J et al: Accomodative intraocular lens tilting. Am J Ophthalmol 140:341, 2005; Hardten DR: The importance of
the refractive aspects of cataract surgery. Am J Ophthalmol 139:906, 2005; Hayashi K, Hayashi H: Intraocular lens factors
that may affect anterior capsule contraction. Ophthalmology 112:286, 2005; Jin GJ et al: Changing indications for
and improving outcomes of intraocular lens exchange. Am J Ophthalmol 140:688, 2005; Lee ES et al: Effect of postoperative
refractive error on visual acuity and patient satisfaction after implantation of the Array multifocal intraocular lens. J
Cataract Refract Surg 31:1960, 2005; Madge SN et al: Optimization of biometry for intraocular lens implantation using
the Zeiss IOLMaster. Acta Ophthalmol Scand 83:436, 2005; Olson RJ et al: New intraocular lens technology. Am J
Ophthalmol 140:709, 2005; Oshika T et al: Ocular higher-order wavefront aberration caused by major tilting of intraocular
lens. Am J Ophthalmol 140:744, 2005; Sacu S et al: Long-term efficacy of adding a sharp posterior optic edge to a
three-piece silicone intraocular lens on capsule opacification: five-year result of a randomized study. Am J Ophthalmol
139:696, 2005; Taketani F et al: Influence of intraocular lens optical design on high-order aberrations. J Cataract Refract
Surg 31:969, 2005.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. Dr. Hardten has been a consultant,
researcher, or speaker for VISX, TLC Vision, AMO, Alcon, Bausch&Lomb, STAAR, Ophtec, and Allergen; Dr.
Colvard has been a consultant for AMO, Eyeonics, Medennium, Rayner, and Oasis.
Dr. Hardten was recorded at the Annual Clinical Conference of the Kansas City Society of Ophthalmology and Otolaryngology
, presented January 6-7, 2006, in Kansas City, Missouri; Dr. Colvard was recorded at the Jules Stein Clinical
and Research Seminar 2005, presented May 20-21, 2005, in Los Angeles by the Jules Stein Eye Institute, David Geffen
School of Medicine at University of California, Los Angeles. The Audio-Digest Foundation thanks Drs. Hardten and Colvard,
and the sponsors for their cooperation in the production of this program.
|
