First and Preliminary Results of Implantation of a New
Posterior Chamber Intraocular Lens

Michael Küchle, Gabriele C. Gusek, Achim Langenbucher, Berthold Seitz

Department of Ophthalmology and University Eye Hospital, University Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen, Germany
Fax +49-9131-8536401
E-Mail kuechle@augen.imed.uni-erlangen.de

Manuscript submitted on September 15, 2000

Supported by Freistaat Bayern (FUTUR-Programm zur Förderung des Forschungs- und Wissenstransfers an den Bayerischen Universitäten)

The authors do not have any commercial, financial or proprietary interest in the intraocular lenses or other devices used in the study.

Abstract

Purpose: To report intra- and early postoperative findings after implantation of a newly designed posterior chamber intraocular lens (PCIOL).

Patients and Methods: In a pilot study, four patients (3 males, 1 female, ages 54, 63, 79 and 86 years) with senile cataract underwent phacoemulsification and implantation of a new hydrophilic acrylic foldable PCIOL between June 27, 2000 and August 25, 2000. The lens was designed after principles elaborated by K.D.Hanna using a finite element model. Intra- and early postoperative clinical findings were documented prospectively. Follow-up was 10 days, 3 weeks (in two patients) and 1 month.

Results: Surgery was uncomplicated in all patients with successful in-the-bag implantation and good centration of the PCIOL. The postoperative course was uncomplicated without inflammation, hemorrhage, synechiae or decentration. Visual acuity improved in all patients.

Conclusions: These very early and preliminary results of our small pilot study are encouraging. However, longer follow-up, more patients and a controlled study with control groups are essential to allow evaluation of safety and potential accommodative power of this new PCIOL.

Key Words: Posterior chamber intraocular lens - cataract surgery phacoemulsification accommodation - presbyopia

Introduction

Immense progress has been achieved in the field of cataract surgery in the last one or two decades with the advent and widespread use of new technologies including posterior chamber intraocular lenses (PCIOL), phacoemulsification, small incision surgery and foldable lenses. Still, there is continued search to optimize PCIOL characteristics. Despite excellent restoration of visual acuity and good biocompatibility of presently used PCIOL types, there is no accommodation in pseudophacic eyes so that patients usually remain presbyopic after cataract surgery. Efforts are being undertaken to develop PCIOLs with the potential to allow accommodation following implantation. Herein we report early intra- and postoperative findings of the first four patients that underwent implantation of a newly designed PCIOL.

Patients and Methods

Patients

This small pilot study was undertaken following the tenets of the declaration of Helsinki. Approval from the ethics committee for human studies of the University Erlangen-Nürnberg was granted for the study. All patients received an extensive and detailed written and oral explanation of the surgical procedure and the characteristics of the new PCIOL. Lengthy discussions of all potential short-term and long-term risks of implantation of the new PCIOL took place between the patients and the surgeon. All patients were given the option of undergoing implantation of a conventional PCIOL. All patients signed a specially elaborated document of informed consent.

Between June 27, 2000 and August 25, 2000, four patients (3 males, 1 female, ages 54, 63, 79 and 86 years) with senile cataract underwent phacoemulsificaton and implantation of a new acrylic foldable PCIOL in our institution. All interventions were performed by one surgeon (MK) in a standardized fashion: After dissection of the conjunctiva at the limbus, a 3 mm sclerocorneal tunnel incision was created. After continuous curvilinear capsulorhexis with a diameter of 5.0 mm, the nucleus was emulsified, residual cortex was removed and the posterior capsule was vacuum-cleaned. Then, the capsular bag was filled with a high-viscosity hyaluronic agent and the incision was enlarged to 3.2 mm. The PCIOL was placed in a cartridge, folded and implanted into the capsular bag with use of an injector. After spontaneous unfolding of the PCIOL optic, the haptics were carefully unfolded with a position hook inside the peripheral capsular bag. After complete aspiration of the viscoelastic agent, the conjunctiva was closed by cauterisation. Following surgery, the patients were treated with combined antibiotic and corticosteroid eye drops (dexamethasone sodium phosphate 0.03% and gentamicin sulfate 0.3% twice a day and tropicamide 0.5% twice daily). After 5 days, the combined antibiotic/steroidal eye drops were discontinued and changed to prednisone acetate 1% eye drops 5 times a day for 4 weeks.

Exclusion criteria were previous intraocular surgery, previous ocular trauma, phacodonesis, pseudoexfoliation syndrome and diabetes mellitus. In one patient, extensive areolar macular atrophy was diagnosed before surgery. However, this was considered not to be a contraindication against surgery and the patient opted for implantation of the new PCIOL despite expected limitation of postoperative visual acuity. In two patients, mild macular drusen were present.

Postoperative follow-up of the patients was 10 days, 3 weeks (in two patients) and 1 month.

PCIOL

Based on concepts by K.D. Hanna and on finite element models, a new acrylic hydrophilic foldable single-piece PCIOL has been designed and manufactured. The IOL optic diameter was 6.0 mm, and the total diameter of the haptics was 9.7 mm. This PCIOL was provided to our group for clinical evaluation. In earlier laboratory studies using porcine cadaver eyes and in human donor eyes that were not suitable for corneal transplantation, we had refined methods of intraocular implantation of this PCIOL.

Examinations

All patients underwent complete preoperative and postoperative examination one day, three days, one week, three weeks (3 patients) and one month (1 patient) after surgery. Examinations included slit-lamp evaluation, laser flare-cell photometry [1-4], applanation tonometry, keratometry, corneal videotopography, Orbscan evaluation, corneal specular microscopy, subjective refraction, examination with an autorefractor, sciascopy, evaluation with the Zeiss IOL-Master, and photodocumentation.

Results

Surgery was uncomplicated in all patients. The PCIOLs could be safely folded within the injection cartridge without damage to the optic or the haptics. After injection into the capsular bag, the PCIOL optics slowly unfolded whereas the haptics remained folded. By careful bimanual manipulation with positioning hooks, it was possible to slowly unfold the haptics inside the peripheral capsular bag without damage to the haptics, to the capsule or to the zonules. In all of the patients, successful in-the-bag implantation was achieved. After unfolding of the haptics, the PCIOL was well centered inside the capsular bag and did not show a tendency towards decentration or subluxation. It was possible to rotate the PCIOL inside the capsular bag with the haptics remaining unfolded and the lens optic remaining centered. The viscoelastic agent could be easily aspirated. After complete removal of the viscoelastic, the lens was still positioned in a stable position. The capsulorhexis remained intact in all patients, no rupture of anterior or posterior capsule or vitreous loss occurred.

The postoperative course was uneventful in all patients during follow-up. The cornea was clear, the anterior chamber quiet, the PCIOL well centered inside the capsular bag. None of the patients developed inflammatory fibrin reactions, synechiae or macrophages on the PCIOL optic. The intraocular pressure remained in the normal range in all patients at all times without antiglaucoma medication. Laser flare values were normal 1 week after surgery in three patients and were mildly elevated (12.2 photon counts/ms) in one patient up to one week after surgery, indicating only minimal disruption of the blood-aqueous barrier caused and absence of a persistent inflammatory response.

Visual acuity improved in all patients according to macular status with best-corrected postoperative visual acuity between 20/200 (patient with areolar macular atrophy) and 20/22.

All patients were very content with the results of surgery.

Discussion

Presbyopia remains one of the unsolved problems in ophthalmology. Many studies have focussed on mechanisms leading to loss of accommodation in presbyopia and on possible solutions [5-10]. Examinations using ultrasound biomicroscopy and magnetic resonance imaging have indicated that the human ciliary body does not lose much of its contractility in the senium and that presbyopia is mainly caused by age-related changes of the lens and the lens capsule [8,10]. In the past, many surgical treatment options for presbyopia have been proposed including scleral expansion surgery [6], zonal photorefractive keratectomy [11], implantation of corneal inlays [12], and implantation of diffractive multifocal [13-15] or bifocal [16] PCIOL. However, these treatment options have so far achieved no, very little or at best limited success. Furthermore, except for scleral expansion surgery, which has been shown to be ineffective [17,18], none of the proposed treatment options for presbyopia have the potential to achieve true accommodation but they all rely on bi- or multifocality with reduction of contrast sensitivity.

Another experimental approach to preserve or restore accommodation after cataract surgery is endocapsular injection of a pliable intraocular lens material ("Phaco-Ersatz") [19,20]. This approach appears very promising but is still in a relatively early experimental phase.

In the present study, implantation of a new PCIOL appeared to be safe with uncomplicated intra- and early postoperative course. The PCIOL was well centered within the capsular bag and was well tolerated in the eye.

However, with regard to the results of our study, it has to be kept in mind that this is only a very preliminary pilot study with a very limited number of patients and with very short follow-up. Further studies with more patients, with much longer follow-up and with study designs including evaluation of control groups of patients with standard rigid and foldable PCIOL are absolutely necessary in order to allow evaluation of safety of this new PCIOL. At this point, no definitive answers as to the accommodative potential of this new PCIOL are possible. However, there were some indications that the newly designed PCIOL may show some accommodative activity after implantation in our patients. This, and the fact that there were no intra- or postoperative problems or complications in our patients thus far, encourages us to continue our investigations to evaluate this new PCIOL. Hopefully, further studies will lead to better understanding of the accommodative process in presbyopic patients and to the development of PCIOLs with accommodative power.

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