11 Presbyopia – Cataract Surgery with Implantation of the AccommodativePosterior Chamber Lens 1CU

with Implantation of the Accommodative Posterior Chamber Lens 1CU

Nhung X. Nguyen, Achim Langenbucher, Berthold Seitz, M. Küchle

CORE MESSAGES

2 The 1CU (HumanOptics, Erlangen, Germany) is a one-piece hy- drophilic acrylic IOL with a spherical optic (diameter 5.5 mm), a total diameter of 9.8 mm, and four specifically designed haptics with transmission elements to allow anterior movement of the lens optic secondary to contraction of the ciliary muscle.

2 Patients with 1CU showed a larger accommodative range and bet- ter distance-corrected near visual acuity than those in a control group with conventional IOLs.

2 Refraction, accommodative range, and lens position all remained stable without signs indicating a systemic trend towards myopia, hypermetropia, posterior chamber IOL dislocation or regression of accommodative properties.

2 The incidence and postoperative time point of significant posterior capsular opacification necessitating Nd:YAG capsulotomy in pa- tients with 1CU are equal to those after implantation of hydrophilic acrylic IOLs reported in the literature. After uncomplicated YAG cap- sulotomy, pseudophakic accommodation capabilities were com- pletely restored.

2 Further studies are necessary and are presently being conducted.

These include (1) longer follow-up of patients with the 1CU posteri- or chamber IOL to test long-term stability of posterior chamber IOL position, refraction, and pseudophakic accommodation and (2) a randomized, double-masked, multicenter design to prove defini- tively the superiority of the 1CU posterior chamber IOL over con- ventional posterior chamber IOLs.

11

11.1 Introduction

Presbyopia remains one of the great unsolved challenges in ophthalmology. Ever since von Helmholtz [1], much research has been con- ducted concerning mechanisms of accom- modation, presbyopia and potential solutions [2–8].

Despite excellent restoration of visual acuity and good biocompatibility of present- ly used posterior chamber intraocular lenses (PCIOL), there is no accommodation in pseudophakic eyes so that patients usually re- main presbyopic after cataract surgery. New- er attempts surgically to correct or reduce presbyopia, including scleral expansion sur- gery, zonal photorefractive keratectomy, or implantation of corneal inlays, so far have achieved no or very limited success in solving the problem [9–11]. Multifocal intraocular lenses (IOLs) allow for improved uncorrected near vision, but at the cost of reduced con- trast sensitivity and loss of image quality [12]. This problem has only partly been solved by the introduction of diffractive and bifocal PCIOL [13]. Therefore, in the past few years, there has been increased interest in the development of new IOL devices to achieve active, ciliary muscle-derived accommoda- tion by optic shift principles without reduc- ing image quality. Among these new IOLs, a new accommodative PCIOL (1CU, Hu- manOptics, Erlangen, Germany) has been de- signed after principles elaborated by K.D.

Hanna. This PCIOL is intended to allow ac- commodation by anterior movement of the lens optic (optic shift) secondary to contrac- tion of the ciliary muscle.

11.1.1 Definitions

In the literature, various terms such as ac- commodation, pseudo-accommodation and apparent accommodation are being used in- terchangeably with regard to pseudophakic eyes. We define pseudophakic accommoda-

tion as dynamic change of the refractive state of the pseudophakic eye caused by interac- tions between the contracting ciliary muscle and the zonules–capsular bag–IOL, resulting in change of refraction at near fixation. Fur- thermore, we define pseudophakic pseudo- accommodation (apparent accommodation) as static optical properties of the pseudopha- kic eye independent of the ciliary muscle, re- sulting in improved uncorrected near vision.

11.1.2 Anatomy and Description of the 1CU Accommodative Intraocular Lens

Several studies using impedance cyclogra- phy, ultrasound biomicroscopy and magnetic resonance imaging have shown that the cil- iary body retains much of its contractility in older patients [5–7]. Furthermore, modern technology allows refined finite element computer methods to simulate the changes of the ciliary body–zonular–lens apparatus dur- ing accommodation. Based on these models, the 1CU PCIOL was developed to allow trans- mission of the contracting forces of the cil- iary body into anterior movement of the lens optic to achieve pseudophakic accommoda- tion. This focus shift principle should allow a defined amount of accommodation, theoreti- cally 1.6–1.9 D per 1-mm anterior movement of the PCIOL optic using the Gullstrand eye.

11.1.3 1CU Posterior Chamber Intraocular Lens

Based on concepts by K.D. Hanna and on fi-

nite element computer simulation models, a

new acrylic hydrophilic foldable single-piece

PCIOL has been designed and manufactured

(Type 1CU, HumanOptics AG, Erlangen, Ger-

many). The spherical optic has a diameter of

5.5 mm, with a total diameter of the PCIOL of

9.8 mm (Fig. 11.1). This PCIOL is intended to

allow accommodation by anterior movement

of the optic (focus shift) secondary to con- traction of the ciliary muscle. To achieve this aim, the lens haptics are modified with trans- mission elements at their fusion with the lens optic. In earlier laboratory studies in porcine eyes and human donor eyes not suitable for corneal transplantation, we have refined methods for intraocular implantation of this PCIOL. The 1CU PCIOL is CE-approved.

11.2 Indications

and Contraindications

At present, only patients with cataract (i.e.

clinically manifest and visually disturbing lens opacities) are candidates for lens ex- change with implantation of the 1CU accom- modative IOL.

We have carefully observed exclusion cri- teria, including manifest diabetic retinopa- thy, previous intraocular surgery, previous se- vere ocular trauma involving the lens, the zonules or the ciliary body, visible zonulo- lysis, phacodonesis, pseudoexfoliation syn- drome, glaucoma, uveitis, high myopia, and high hypermetropia.

Furthermore, this kind of surgery will not result in satisfying clinical results in patients with severe age-related macular degenera- tion or marked glaucomatous optic atrophy.

If there are problems during cataract sur- gery, such as radial tears of the capsulorrhex- is, diameter of capsulorrhexis >5.5 mm, zonulolysis, rupture of the posterior capsule, or vitreous loss, the 1CU accommodative IOL should not be implanted and surgery should be converted to implantation of a conventional PCIOL.

11.3 Surgical Techniques

and Main Outcome Measures

Generally, any of the modern small-incision phacoemulsification techniques may be used to remove the lens nucleus and lens cortex be- fore the 1CU accommodative IOL is implanted.

11.3.1 Anesthesia

Phacoemulsification and implantation of the 1CU accommodative IOL may be safely per- formed under local or topical anesthesia. The surgeon may choose the method for cataract surgery with which he is most comfortable.

No specific modifications of anesthesia are necessary for implantation of the 1CU ac- commodative IOL.

11.3.2 Procedure (General)

Phacoemulsification of the lens nucleus and cortical cleaning are not very different from routine cataract surgery. The surgeon may choose the incision and phacoemulsification technique that he routinely uses for cataract surgery. Either a clear cornea or a sclero- corneal incision may be used. If possible, the incision should be placed in the steepest corneal meridian to reduce any pre-existing corneal astigmatism. The capsulorrhexis is of

Fig. 11.1. Schematic drawing of the 1CU accom- modative intraocular lens

great importance: it should be small enough (maximum 5.0 mm) to safely and circularly cover the peripheral optic of the IOL (diame- ter 5.5 mm). In addition, the capsulorrhexis should be round and well centered to allow for the elastic forces of the zonules and lens cap- sule to be equally distributed. Meticulous re- moval of all lens cortex and polishing of the posterior lens capsule is important to reduce the risk of capsular fibrosis and posterior cap- sular opacification. Any of the commercially available viscoelastic agents may be used.

11.3.3 Procedure (Specifics)

Implantation and placement of the 1CU ac- commodative IOL is the main step of the sur- gical procedure. It differs in some aspects from implantation of standard IOLs but is relatively easily accomplished. Intraocular lens implantation is best performed with a cartridge and an injector. Folding and im- plantation with a forceps is also possible but may be associated with an increased risk of damaging the thin and delicate lens haptics.

An incision width of 3.2 mm is usually suffi- cient. The 1CU accommodative IOL is placed into the cartridge with the edges of the hap- tics pointing upwards/anterior. When folding the lens inside the cartridge, care should be executed to avoid damage to the haptics. Af- ter completely filling the anterior chamber and the capsular bag with a viscoelastic agent, the lens is then implanted into the an- terior chamber or directly into the capsular bag. If the lens optic is placed in front of the capsular bag, it may be easily pressed down into the capsular bag with a cannula or a spat- ula. Then the four lens haptics are unfolded inside the capsular bag with a push–pull hook or an iris spatula. The viscoelastic agent should be completely removed also from be- hind the lens to prevent development of cap- sular block or capsular distension syndrome, which might theoretically develop otherwise because of the relatively small size of the cap-

sulorrhexis. The lens haptics should be placed at the 12–3–6–9 o’clock positions.

11.3.4 Postoperative Treatment

Postoperative care and medications are simi- lar to those of routine cataract surgery. Post- operative medication usually includes topical antibiotics, topical corticosteroids, and topical short-acting mydriatics such as tropicamide.

Our current postoperative regimen in- cludes combined antibiotic and corticos- teroid eye drops (dexamethasone sodium phosphate 0.03% and gentamicin sulfate 0.3%) twice daily and tropicamide 0.5%

twice daily. After 5 days, the combined antibi- otic/steroidal eye drops are discontinued and changed to prednisone acetate 1% eye drops five times a day for 4 weeks. The tropicamide eye drops are also discontinued after 4 weeks.

No atropine is used.

11.3.5 Assessment

of Accommodation

and Main Outcome Measures

In pseudophakic patients, objective measure-

ment techniques of refraction or accommo-

dation are more difficult to apply due to a sig-

nificant optical reflex from the anterior as

well as from the posterior surface of the arti-

ficial lens. As the refractive index of the arti-

ficial lens material is significantly higher than

that of the crystalline lens, and as the surfaces

of the artificial lens are mostly spherical, in

contrast to the aspherical crystalline lens

where a lot of (higher-order) optical aberra-

tions are present, the Purkinje images III and

IV may interfere with the measurements of

auto- and videorefractometers. Thus, some of

the measurement methods do not yield

proper results in pseudophakic patients and

should only be used with great care, whereas

other methods have to be modified to provide

correct results after cataract surgery. Further-

more, pupillary constriction induced by ac- commodation and/or pilocarpine may inter- fere with correct measurements. Figure 11.2 gives an overview of the different methods used to determine accommodation amplitude.

In addition to the routine early postopera- tive examinations, all patients underwent de- tailed examinations at 6 weeks, then every 3 months until 1 year postoperatively, then every 6 months, with the following tests [14]:

∑

Patients were carefully refracted for dis- tance, the spherical equivalent (SEQ) was calculated in diopters (D) due to form (SEQ = spherical refraction (D) + 0.5*cylindric refraction (D)). Distance visual acuity was determined with best dis- tance correction. Subsequently, near read- ing vision was determined using the same distance correction and Birkhäuser reading charts (Scalae Typographicae Birkhaeuseri, Birkhäuser Verlag, Basel, Switzerland) at a distance of 35 cm with an illumination of 70 cd/m

. The reading charts were held by the patients at normal reading position, i.e.

angled slightly inferiorly by 20°.

∑

Accommodation was determined subjec- tively using the same distance correction.

With an accommodometer (Clement Clarke RAE, Frohnhäuser, Unterhaching, Germany), a small reading chart was slow- ly moved towards the eye from a distance of 1 m (with a spherical reading glass of +2 diopters added to the distance correc-

tion) until the patient noted blurring of the optotypes. Reading distance was con- verted to diopters and corrected for the 2-diopter near addition to get the subjec- tive accommodation or – reconverted to distance – to get the subjective near point.

∑

Near and distance refractions were deter- mined by streak retinoscopy [13]. All retinoscopy was performed by one skilled examiner who was not informed as to whether the individual patient had re- ceived the new PCIOL or a conventional PCIOL. For distance retinoscopy, patients were asked to fixate a visual chart project- ed at a distance of 5 m. For near retino- scopy, patients were asked to maximally fixate a near chart. Accommodative range was the difference between near and dis- tance refractions.

∑

Defocusing was performed with a far dis- tance correction for the patient and reading charts at 5 m distance. Visual acuity was measured with defocusing of the patient in steps of 0.5 diopters, starting with +0.5, 0, –0.5, –1.0, ..., –3.0 diopters spherical glasses.

As accommodation amplitude we defined the minus lens with which the patient re- tained visual acuity of 0.4 (20/50).

∑

Anterior chamber depth indicating the position of the PCIOL was measured with the IOL Master (Zeiss, Jena, Germany) without medical influence of pupil size or the state of the ciliary muscle.

Fig. 11.2. Different principles of measuring accom- modation in pseudophakic patients. Classifica- tion was done in the dynamic and static condition as well as in objective and subjective measure- ment methods

11.4 Clinical Outcomes 11.4.1 Safety

The 1CU PCIOL could be inserted without complications in all patients, and the PCIOLs were well centered in the capsular bag at all times (Fig. 11.3). No signs of contraction of the capsular bag or of the anterior lens cap- sule, nor decentration or dislocation of the 1CU PCIOL was observed in any of the pa- tients during follow-up [15].

None of the patients developed inflamma- tory fibrin reactions, synechiae or macro- phages on the PCIOL optic. Using laser flare photometry, only a minimal and short-last- ing alteration of the blood–aqueous barrier was observed [16]. Four weeks postoperative- ly, aqueous flare was normal in all patients and remained stable below the normal limit for up to 12 months. No signs of persisting in-

flammation or pigment dispersion were de- tected. The intraocular pressure remained in the normal range (<20 mmHg) in all patients at all times without antiglaucoma medication.

11.4.2 Accommodation Ability in Comparison

with Conventional Intraocular Lenses

To compare the accommodative ability of patients with 1CU PCIOL with that of pa- tients with conventional PICOL, a non-ran- domized study analyzed the 6-months results of 20 patients with 1CU and 20 age-matched patients with three different PCIOLs (one- piece polymethyl methacrylate lenses in 11 eyes, one-piece hydrophilic acrylic lenses (K3, HumanOptics, Erlangen, Germany) in four eyes, and three-piece hydrophobic acrylic

Fig. 11.3. Transillumination photograph of 1CU localized in the capsular bag 1 year (a1 and a2) and 2 years (b1 and b2) after implantation. The arrow shows the border of well-centered round capsulorrhexis

lenses (Acrysof MA 60 BM, Alcon, Freiburg, Germany) in five eyes).

Mean postoperative best corrected dis- tance visual acuity was 1.0±0.16 in the 1CU group and 0.93±0.11 in the control group, and the difference between the two groups was not statistically significant (p=0.13).

Median near visual acuities determined with best distance correction and Birkhäuser charts at 35 cm were significantly higher (0.4, range 0.2–0.6) in the 1CU group than in the control group (0.2, range 0.1–0.3, p<0.001).

Median subjective near points with best distance correction were 55 cm (range 37–100) in the 1CU group and 86 cm (59–128) in the control group. Mean accommodative ranges as determined by subjective near point were 1.83±0.49 D (range 1.0–2.7) in the 1CU group and 1.16±0.27 D (0.78–1.69) in the control group. Mean accommodative ranges as determined by defocusing were 1.85±0.43 D (1.0–2.5) in the 1CU group and 0.64±0.21 D (0.5–1.0) in the control group. Mean accom- modative ranges as determined by retino- scopy were 0.98±0.55 D (0.13 to +2.0) in the 1CU group and 0.17±0.22 D (0.25 to +0.5) in the control group (Table 11.1, Fig. 11.4).

Table 11.1. Findings in two groups (1CU group and age-matched controls with conventional intraocular lens- es) 6 months after implantation of posterior chamber intraocular lens. Indicated are mean, standard deviation, median and range

1CU group Control group Difference between two groups and level of significance

Best corrected distance 1.0±0.16 0.95±0.11

visual acuity (D) 1.0, 0.63–1.25 1.0, 0.7–1.0 p=0.13

Near visual acuity with 0.36±0.10 0.16±0.06

best distance correction 0.4, 0.2–0.6 0.2, 0.1–0.3 p<0.001 (Birkhäuser reading charts in 35 cm)

Accommodative range 1.83±0.49 1.06±0.27 0.67

determined by near point (D) 1.85, 1.0–2.7 0.9, 0.78–1.35 p<0.001

Accommodative range 1.85±0.43 0.64±0.21 1.21

determined by defocusing (D) 2.0, 1.0–2.5 0.5, 0.5–1.0 p<0.001

Accommodative range 0.98±0.55 0.17±0.22 0.81

determined by streak retinoscopy (D) 0.88, –0.13 to +2.0 0.25, –0.25 to +0.5 p<0.001

Fig. 11.4. Box plots indicating accommodative range (D) of the two groups (1CU group and age- matched controls with conventional intraocular lenses). The accommodative range was quantified using three different methods: subjective near point, defocusing and streak retinoscopy. The box- es include 50% of measured values (between the 25th and 75th percentiles) and show the position of the median (horizontal line). The error bars indi- cate 1.5 times the interquartile distance from the upper and lower box edges. The difference between the two groups is statistically significant (p=0.001)

Thus, the mean treatment effects (differ- ence between 1CU group members and con- trols) were 0.67 D (subjective near point), 1.21 D (defocusing), and 0.81 D (retinoscopy). All differences between the 1CU and control groups according to accommodation ability were statistically highly significant (p<0.001) (Table 11.1).

A major problem in designing studies to investigate accommodative PCIOLs in pa- tients is to choose adequate methods of quan- tifying pseudophakic accommodation [12].

In this present study, three methods of more accurately measuring pseudophakic accom- modation as the major outcome measure were chosen. Two of these rely on subjective patient information (near point and defocus- ing), whereas the third method uses more objective retinoscopy with near and distance fixation of the patient. With all three meth- ods, a significantly higher accommodative range in the 1CU group, with differences of mean values of 0.67, 1.21, and 0.81 D between the 1CU group and the control group were found. This, in our opinion, puts the results of our study on a broader and safer base [17].

Even though the amount of additional pseudophakic accommodation that we achieved was relatively limited (depending on the measurement method, an excess of between 0.67 and 1.21 D in comparison with the control group with conventional PCIOL), we have the clinical impression that the de- gree of additional pseudophakic accommo- dation is useful for the patients in daily life.

This may be explained by the fact that, in ad- dition to the mentioned amount of true pseudophakic accommodation, other mecha- nisms of pseudo-accommodation, such as in- creased depth of focus by pupillary constric- tion, spherical aberration, and multifocality of PCIOL and cornea, may also contribute to or further increase the quality of near vision.

11.4.3 Stability of Refraction, Accommodation, and Lens Position

The design of the 1CU PCIOL includes modi- fication of lens haptics with reduced thick- ness near the lens optic for higher flexibility to allow reversible anterior movement of the lens optic secondary to contraction of the ciliary muscle. Thus, one could imagine the theoretical potential problem with the 1CU PCIOL in that progressive and/or irreversible anterior movement of the PCIOL optic brought about by shrinkage and contraction of the capsular bag might occur. This problem could consequently result in a myopic shift of refraction and loss of pseudophakic accom- modation.

Prospective studies that followed patients with the 1CU PCIOL showed that refraction, anterior chamber depth and accommodative range all remained stable without signs indi- cating a systemic trend towards myopia, hypermetropia, PCIOL dislocation or regres- sion of accommodative properties [18].

We found a distance refraction (spherical equivalent, mean and standard deviation) of –0.28±0.54 D after 3 months, –0.29±0.52 D af- ter 6 months, and –0.21±0.54 D after 12 months (Table 11.2). Best corrected distance visual acuity was 20/16–20/25 in all patients and remained stable during follow-up. Mean accommodative range determined by near point was 1.93±0.47 after 3 months, 1.85±0.62 after 6 months and 2.02±0.38 D after 12 months (Fig. 11.5). Mean anterior chamber depth (Zeiss IOL Master) without pharmaco- logical induction of ciliary muscle contraction was 4.40±0.44 mm after 3 months, 4.35±

0.50 mm after 6 months, and 4.25±0.53 mm

after 12 months (Table 11.2). Mean distance-

corrected near visual acuity (Birkhäuser

charts in 35 cm) was 0.41±0.15 after 3 months,

0.37±0.12 after 6 months, and 0.39±0.11 after

12 months (Table 11.2). None of these compar-

isons, neither overall nor pairwise, reached

statistical significance (p>0.1 for all analyses).

Our results indicate that for up to 12 months, the 1CU PCIOL shows no tendency of myopization, anterior movement of the lens optic or loss of distance-corrected near visual acuity. One possible explanation for these encouraging observations may be that we observed very little fibrosis of the capsu- lar bag or the anterior and posterior lens cap- sule. This may be a result of the design of the 1CU PCIOL and the fact that we carefully performed a well-centered round capsulor- rhexis of 5 mm with the remaining anterior lens capsule circumferentially covering the rim of the PCIOL optic. Furthermore, we carefully observed inclusion and exclusion criteria that excluded eyes with potential zonular weakness and tendencies to develop increased fibrosis of the lens capsule, i.e.

traumatic changes, pseudoexfoliation, and proliferative diabetic retinopathy.

Based on our findings, we conclude that it is unlikely that problems such as anterior vaulting, anterior movement or dislocation of the 1CU PCIOL will occur after more than 12 months. Nevertheless, we believe that further studies with longer follow-up and a random- ized, masked, multicenter design are needed to analyze further the 1CU PCIOL with regard to long-term biocompatibility and accommodative properties.

Table 11.2. Findings in 30 eyes of 30 patients at different time points following implantation of the 1CU ac- commodative posterior chamber intraocular lens. Indicated are mean, standard deviation, median and range

Three months Six months Twelve months

Spherical equivalent –0.28±0.54 –0.29±0.52 –0.21±0.54

of distance refraction (D) –0.25, –1.38 to +0.75 –0.25, –1.38 to +0.5 –0.25, –1.13 to +0.5

Accommodative range 1.93±0.47 1.85±0.62 2.02±0.38

determined by near point (D) 2.0, 1.0–2.78 1.85, 0.5–2.7 2.0, 1.32–2.56

Anterior chamber depth (mm) 4.40±0.44 4.35±0.50 4.25±0.53

4.47, 3.30–5.21 4.45, 3.30–5.23 4.30, 3.28–4.97

Near visual acuity with best 0.41±0.15 0.37±0.12 0.39±0.11

distance correction (Birkhäuser 0.4, 0.2–0.7 0.3, 0.2–0.6 0.4, 0.3–0.6 reading charts in 35 cm) (J3, J10–J1) (J7, J10–J1) (J3, J7–J1) and corresponding Jaeger values

Fig. 11.5. Box plots showing accommodative range (D) determined by near point at different time points after implantation of the new accom- modative 1CU posterior chamber intraocular lens in 15 patients. The boxes include 50% of measured values (between the 25th and 75th percentiles) and show the position of the median (horizontal line).

The error bars indicate 1.5 times the interquartile distance from the upper and lower box edges

11.4.4 Accommodation Ability after Nd:YAG Capsulotomy Posterior capsular opacification (PCO) is the most common complication of cataract sur- gery, with a reported incidence of 10–50% [1, 2, 4, 21 ]. In cases of vision-impairing PCO, Nd:YAG laser capsulotomy is usually per- formed to improve visual function. The rate, the postoperative time point of PCO necessi- tating YAG capsulotomy and the accommo- dation ability after Nd:YAG capsulotomy in patients with 1CU PCIOL were evaluated in a prospective study of 65 patients with a mean postoperative follow-up of 23 ±10 (median 24, range 4–40) months.

A clinically relevant PCO with significant decrease of visual acuity (0.4 ±0.2 D) and a need for Nd:YAG capsulotomy was diagnosed in 20% of all patients with 1CU between 15 and 22 (mean 20 ±4, median 20) months post- operatively. All patients reported that the first subjective visual impairment noted was a problem with reading. It was not possible to determine the accommodation range imme- diately before capsulotomy in most of the patients. All capsulotomies performed were uncomplicated. No decentration or disloca- tion of the 1CU PCIOL was observed in any of the patients during follow-up.

Six weeks after capsulotomy, best correct- ed distance visual acuity was improved (1.1 ±0.1). Near visual acuity with best dis- tance correction was 0.4 ±0.1. Accommoda- tive range determined by near point was 1.9 ±0.4 D, and by defocusing was 1.7±0.4 D (Fig. 11.6). Six weeks after capsulotomy, none of the measurements of accommodative range were statistically different from the 12- month results before occurrence of PCO (p>0.5) (Table 11.3, Fig. 11.7).

The rate of significant PCO necessitating Nd:YAG capsulotomy in our patients with 1CU was about 20% during a mean follow-up of 23 ±10 months, occurring mainly after 15 months postoperatively. The incidence and time point are equal to results after implanta-

tion of hydrophilic acrylic IOLs reported in the literature [18–20].

Interestingly, we found that all patients with PCO complained first about their near visual acuity but not about their distance visual acuity, although the distance visual acuity also decreased. A possible explanation for this finding is that PCO may occlude the entire pupillary area when reading as the pupil contracts by accommodation.

The results of the present study showed that 6 weeks after capsulotomy the accommo- dation ability and visual acuity had improved significantly to the levels before PCO oc- curred. Our results indicate that Nd:YAG cap- sulotomy may not affect the accommodation ability of the 1CU.

Fig. 11.6. Box plots showing accommodative range (D) determined by defocusing at different time points before and 6 weeks after Nd:YAG cap- sulotomy in patients after implantation of the new accommodative 1CU posterior chamber intraocu- lar lens. The boxes include 50% of measured val- ues (between the 25th and 75th percentiles) and show the position of the median (horizontal line).

The error bars indicate 1.5 times the interquartile distance from the upper and lower box edges. Val- ues more than 1.5 interquartile ranges away from the box are shown as circles

Table 11.3. Findings in 15 eyes of 15 patients at different time points following implantation of the 1CU ac- commodative posterior chamber intraocular lens before and 6 weeks after Nd:YAG capsulotomy. Indicated are mean, standard deviation and median

Three Six Twelve At time point Six weeks after months months months of YAG YAG capsulotomy

capsulotomy

Best corrected 1.0±0.28 1.0±0.28 0.96±0.22 0.4±0.10 1.0±0.1

distance visual 1.0 1.0 1.0 0.4 1.0

acuity (D)

Near visual acuity 0.41±0.15 0.37±0.12 0.39±0.11 0.13±0.14 0.39±0.08

with best distance 0.4 0.4 0.4 0.1 0.4

correction (Birkhäuser chart in 35 cm)

Subjective 48±9.4 53±8.8 53±9.4 107±10.6 52±7.5

near point (cm) 50 53 52 100 52

Accommodative

range (D) determined 1.93±0.47 1.85±0.62 2.02±0.38 0.7±0.3 1.95±0.6

by near point 2.0 1.85 2.0 0.5 1.9

Accommodative 1.88±0.47 1.82±0.33 1.88±0.47 0.06±0.18 1.88±0.47

range (D) determined 1.75 1.5 1.75 0.0 1.75

by defocusing

Anterior chamber 4.4±0.2 4.3±0.3 4.2±0.4 4.3±0.3 4.4±0.3

depth (mm) 4.4 4.4 4.3 4.4 4.3

Fig. 11.7. aTransillumination photograph of 1CU localized in the capsular bag before Nd:YAG cap- sulotomy. The best corrected distance visual acuity was 0.5, near visual acuity with best corrected distance correction was less than 0.1; it was not possible to determine the accommodation range.

b6 weeks after Nd:YAG capsulotomy. The best cor- rected distance visual acuity was 1.0, near visual acuity with best corrected distance correction was 0.4, accommodation range determined by near point was 1.7 D, and by defocusing was 1.5 D

References

1. Von Helmholtz H (1855) Über die Akkommo- dation des Auges. Albrecht von Graefes Arch Klin Exp Ophthalmol 1:1–74

2. Rohen J (1969) Akkommodationsapparat. In:

Velhagen K (ed) Der Augenarzt, Bd 1. Thieme, Leipzig, pp 51–69

3. Bacskulin A, Gast R, Bergmann U, Guthoff R (1996) Ultraschallbiomikroskopische Darstel- lung der akkommodativen Konfigurations- änderungen des presbyopen Ziliarkörpers.

Ophthalmologe 93:199–203

4. Glasser A, Kaufman PL (1999) The mechanism of accommodation in primates. Ophthalmolo- gy 106:863–872

5. Ludwig K, Wegscheider E, Hoops JP, Kampik A (1999) In vivo imaging of the human zonular apparatus with high-resolution ultrasound.

Graefe’s Arch Clin Exp Ophthalmol 237:

361–371

6. Strenk SA, Semmlow JL, Strenk LM et al (1999) Age-related changes in human ciliary muscle and lens: a magnetic resonance imaging study.

Invest Ophthalmol Vis Sci 40:1162–1169 7. Swegmark G (1969) Studies with impedance

cyclography on human ocular accommoda- tion at different ages. Acta Ophthalmol 47:

1186–1206

8. Weale R (1989) Presbyopia toward the end of the 20th century. Surv Ophthalmol 34:30

The 1CU (HumanOptics AG, Erlangen, Germany) is an acrylic hydrophilic foldable sin- gle-piece PCIOL with a spherical optic diameter of 5.5 mm and a total diameter of 9.8 mm. This PCIOL is intended to allow accommodation by anterior movement of the optic (focus shift) secondary to contraction of the ciliary muscle.To achieve this, the lens haptics are modified with transmission elements at their fusion with the lens optic.With adequate indication and surgical technique, the 1CU IOL has been safe and effective in our hands.

Even though the amount of additional pseudophakic accommodation that is achieved in patients with accommodative 1CU was relatively limited (depending on the measurement method, an excess of between 0.67 and 1.21 D in comparison with the control group with conventional PCIOL), the degree of additional pseudophakic accommodation is useful for the patients in daily life.

The rate and postoperative time point of significant PCO necessitating Nd:YAG cap- sulotomy in our patients with 1CU are equal to results after implantation of hydrophilic acrylic IOLs reported in the literature. After uncomplicated capsulotomy, pseudophakic accommodation capabilities were completely restored compared to the results before occurrence of PCO.

One potential drawback of evaluation of pseudophakic accommodation in our pa- tients with 1CU was that objective measurement methods were not used to quantify pseudophakic accommodation at the various time points. However, there is a lack of measurement methods for use in clinical studies that are easily applicable to patients and that allow exact measurements of pseudophakic accommodation. Recent studies have indicated that after application of miotics, measurement of anterior chamber depth in pseudophakic eyes does not always give accurate, valuable and reproducible results. However, the results of our studies obtained by different examination methods (near visual acuity with best corrected distance refraction, subjective near point, defocusing and streak retinoscopy) indicate good visual function and accommodation ability of the accommodative 1CU PCIOL.

Future research should be directed to improving further the optic and accommoda- tive results of this new generation of accommodative PCIOLs.

FINAL COMMENTS

9. Mathews S (1999) Scleral expansion surgery does not restore accommodation in human presbyopia. Ophthalmology 106:873–877 10. Vinciguerra P, Nizzola GM, Bailo G et al (1998)

Excimer laser photorefractive keratectomy for presbyopia: 24-month follow-up in three eyes.

J Refract Surg 14:31–37

11. Keates RH, Martines E, Tennen DG, Reich C (1995) Small-diameter corneal inlay in pres- byopic or pseudophakic patients. J Cataract Refract Surg 21:519–521

12. Allen ED, Burton RL, Webber SK et al (1996) Comparison of a diffractive bifocal and a monofocal intraocular lens. J Cataract Refract Surg 22:446–451

13. Steinert RF, Aker BL, Trentacost DJ et al (1999) A prospective comparative study of the AMO ARRAY zonal-progressive multifocal silicone intraocular lens and a monofocal intraocular lens. Ophthalmology 106:1243–1251

14. Langenbucher A, Huber S, Nguyen XN et al (2002) Measurement of accommodation after implantation of a new accommodative posteri- or chamber intraocular lens (1CU). J Cataract Refract Surg 18:208–216

15. Küchle M, Nguyen XN, Langenbucher A et al (2002) Implantation of a new accommodative posterior chamber intraocular lens. J Refract Surg 18:208–216

16. Nguyen NX, Langenbucher A, Seitz B et al (2002) Short-term blood-aqueous barrier breakdown after implantation of the 1CU ac- commodative intraocular posterior chamber intraocular lens. J Cataract Refract Surg 28:

1189–1194

17. Küchle M, Seitz B, Langenbucher A et al (2004) Comparison of six-month results of implanta- tion of the 1CU accommodative intraocular lens with conventional intraocular lenses.

Ophthalmology 111:318–324

18. Küchle M, Seitz B, Langenbucher A et al (2003) Stability of refraction, accommodation, and lens position following 1CU accommodative posterior chamber intraocular lens implanta- tion. J Cataract Refract Surg 29:2324–2329 19. Ando H, Ando N, Oshika T (2003) Cumulative

probability of neodymium. YAG laser posteri- or capsulotomy after phacoemulsification.

J Cataract Refract Surg 29:2148–2154

20. Apple DJ, Solomon KD, Tetz MR et al (1992) Posterior capsule opacification. Surv Ophthal- mol 37:73–116

21. Schaumberg DA, Dana MR, Christen WG et al (1998) A systematic overview of the incidence of posterior capsule opacification. Ophthal- mology 105:1212–1221