The phakic intraocular lens implant: in-depth focus on posterior chamber phakic IOLs

Prototype posterior chamber phakic IOL - 35 year follow up

Purpose

To present a case involving a rarely seen prototype posterior chamber phakic IOL (PC-pIOL) in a highly myopic patient with bilateral cataract.

Observations

A 64-year-old male presented to our clinic with poor vision in both eyes. Clinical examination revealed bilateral mature cataract, phacodonesis as well as a PC-pIOL implanted 35 years ago to address his high myopia. The visual acuity (VA) was 20/200 in the right eye and no light perception in the left eye. PC-pIOL extraction as well as 23G pars plana vitrectomy (PPV) and fragmentation surgery was scheduled for the right eye. The left eye was treated conservatively. Successful extraction of the PC-pIOL was performed while it was easy to remove. It was a bow-tie shaped lens with a collar-stud-like button in the middle which extended anteriorly into the anterior chamber through the pupil. PPV with lens fragmentation was successful and the patient was left aphakic in order to avoid the placement of a zero diopter IOL. Final best corrected VA was 20/25 one month post-surgery.

Conclusions and importance

Removal of this rarely seen pIOL was performed without difficulty while excellent VA was achieved. Aphakia following complete vitrectomy represented a viable option in this case. Furthermore, we highlight the clinical manifestations associated with this IOL more than three decades after implantation.

Comparative analysis of two optical biometry devices: high wavelength swept source OCT versus partial coherence interferometry

Purpose

To study the reproducibility of measurements performed with a recently developed multimodal high resolution swept source optical coherence tomography (SSOCT) and to make comparisons with a partial coherence interferometry (PCI) biometer.

Methods

One hundred and fifty-two eyes of 152 subjects were involved in this study with a mean age of 65.71 ± 13.86 years (26–85 years). Anterior surface keratometry (K), anterior chamber depth (ACD), white-to-white (WTW) and axial length (AL) values were recorded by the SSOCT (ANTERION, Heidelberg Engineering Ltd, Germany) and PCI (IOLMaster 500, version 5.5, Carl Zeiss Meditec, Germany). Intraocular lens (IOL) power was calculated based on ANTERION and IOLMaster keratometry values by using five traditional vergence formulas.

Results

Anterior surface simulated keratometry values did not differ significantly between the IOLMaster and ANTERION (P > 0.05). AL measurements were successful in 95% of the cases both with the SSOCT and PCI. No significant difference was disclosed between the two instruments (P = 0.229). For WTW measurements, a significant difference was observed between the two optical biometers (P < 0.0001). The difference between PCI and SSOCT in IOL powers was statistically significant for SRK/T, Hoffer and Holladay formulas (P < 0.001).

Conclusion

Our results implicated an overall good reproducibility of anterior keratometry, AL, ACD and WTW measurements for IOLMaster and ANTERION. The discrepancies between their measurements resulted in significant difference in the calculated IOL power for SRK/T, Hoffer and Holladay formulas, but not for Haigis formula.

Cataract development associated with collagen copolymer posterior chamber phakic intraocular lenses: clinicopathological correlation

PURPOSE

To assess the histopathology of anterior subcapsular cataract associated with a collagen copolymer posterior chamber phakic intraocular lens (pIOL) (Visian Implantable Collamer Lens) using light microscopy after pIOL explantation and cataract surgery.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Laboratory investigation.

METHODS

Pathology specimens related to explanted pIOLs were reviewed and preoperative and postoperative patient data collected. The anterior lens capsules and explanted pIOLs were examined.

RESULTS

Four eyes (3 patients) had pIOL explantation for low vault and anterior subcapsular cataract. The explanted pIOLs were the shorter length models (3, 12.1 mm; 1, 12.6 mm). Anterior segment optical coherence tomography (AS-OCT) confirmed the low pIOL vault before explantation in 2 eyes. Histopathology of the anterior subcapsular cataract showed fibrous metaplasia with a variable number of lens epithelial cell (LEC) layers attached to the inner surface of the anterior capsulorhexis specimens. Light microscopy of the explanted pIOLs showed no pigment on 1 lens, mild pigment deposition on 1 haptic, and pigment deposition throughout the anterior surface of 2 pIOLs.

CONCLUSIONS

Anterior subcapsular cataract associated with the pIOLs was caused by low vaulting (confirmed on AS-OCT) and consequent fibrous metaplasia of the anterior LECs. Surgeons should consider the possibility of anterior subcapsular cataract associated with shorter platforms when selecting a pIOL length for appropriate vault.

Long-term follow-up of first-generation posterior chamber phakic intraocular lens

We present a patient who received a first-generation posterior chamber phakic intraocular lens (PC pIOL) (Fyodorov IOL) to correct myopia 18 years previously. After a long lapse in the follow-up, the patient presented with a reduced endothelial cell count. Although the cataractogenic effect of first-generation PC pIOLs is well known, no sign of cataract was present. The patient was totally satisfied even after 18 years. To our knowledge, this is the first report of a long follow-up of a patient implanted with a first-generation PC pIOL.

Phakic Intraocular Lenses

An analytical review of the data available in the field of phakic intraocular lens implantation was conducted. Particular attention was paid to the more critical issues of intraocular lens sizing and safety guidelines. A comprehensive, competitive analysis of different implantation sites, intraocular lens model designs, and safety guidelines has been included. Specialized biometry techniques, such as very high frequency ultrasound and Scheimpflug imaging, have been reviewed, and a critical review of commercial claims regarding intraocular lens technologies has been included. Clinical studies of phakic intraocular lenses demonstrate increasing promise for the correction of refractive errors not amenable to mainstream excimer laser refractive surgery. The main issues currently revolve around adequate lens design (VHF ultrasound study suggests that custom-design and sizing may be the most effective and safest approach for every phakic IOL model), because these devices will be required to remain physiologically inert and anatomically compatible with internal ocular structures and relations for several decades. The possibility of safe removing or exchanging the IOL should remain a feasible option over time. It is of utmost importance that we continue to critically evaluate current encouraging short-term outcomes, which are being extrapolated to the longer term by ongoing high resolution imaging and monitoring of the anatomical and functional relations of implanted phakic IOLs.

Toric phakic intraocular lens: European multicenter study

OBJECTIVE

To evaluate safety, efficacy, predictability, stability, complications, and patient satisfaction after implantation of Artisan toric phakic intraocular lenses (TPIOLs) for the correction of myopia or hyperopia with astigmatism.

DESIGN

Prospective, nonrandomized, comparative (self-controlled) multicenter trial.

PARTICIPANTS

Seventy eyes of 53 patients (mean, 35 years; range, 22-59 years) with preoperative spherical equivalent between +6.50 and -21.25 diopters (D) and cylinder between 1.50 and 7.25 D.

METHODS

Seventy eyes underwent implantation of a TPIOL with an optical zone of 5.0 mm (Artisan, Ophtec, Groningen, The Netherlands). The dioptric power of the intraocular lens was calculated by considering refraction, keratometry, and anterior chamber depth. The follow-up was 6 months in all cases. Lenses were available in powers ranging from +12.0 D to -23.5 D (spherical equivalent) in 0.5-D increments, with additional cylinder from 1.0 D to 7.0 D, also in 0.5-D increments.

MAIN OUTCOME MEASURES

The main parameters assessed were best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), refraction, endothelial cell count (ECC), intraocular pressure, slit-lamp biomicroscopy, indirect ophthalmoscopy, subjective complaints, and patient satisfaction.

RESULTS

Eyes were divided into group A, myopia (n = 48), with an average preoperative spherical equivalent of -8.90 +/- 4.52 D, and group B, hyperopia (n = 22), with an average preoperative spherical equivalent of +3.25 +/- 1.98 D. No eyes in either group experienced a loss in BSCVA, and 46 eyes gained 1 or more lines of their preoperative BSCVA. In 62 eyes (88.6%), UCVA was 20/40 or better. There was a significant reduction in spherical errors and astigmatism in all cases after surgery. All eyes of both groups were within +/-1.00 D of target refraction, and 51 eyes (72.9%) were within +/-0.50 D of target refraction. There was a 4.5% mean total loss of ECC during the first 6 months. No serious complications were observed. Overall patient satisfaction was very high.

CONCLUSIONS

Six-month clinical trial results demonstrate that implantation of the Artisan TPIOL safely, predictably, and effectively reduced or eliminated high ametropia and astigmatism with one procedure. The refractive effect was stable at 6 months after surgery.

Phakic intraocular lenses

Since Zaldivar's review of phakic intraocular lenses in these pages in 2000 [1**], further reports of experience with this technology have emerged. Their relative advantages and disadvantages over competing technologies are becoming clearer. Clinical trials, including Food & Drug Administration (FDA) trials, have shown predictability, stability, and efficacy. Safety of these implants over the long term remains a concern, but in some situations, at least, phakic intraocular lenses are becoming the refractive correction of choice. This brief review looks at the most recent data to emerge regarding phakic intraocular lenses.

Imaging of posterior chamber phakic intraocular lens by optical coherence tomography

We demonstrate the applicability of optical coherence tomography to visualize the distance between the intraocular lens (IOL) and the lens capsule (lens vault) after implantation of the Staar Collamer posterior phakic IOL, also known as the implantable contact lens (ICL). Maintaining a substantial lens vault may be important to avoid cataract formation, but the lens vault was found to change over time; changes in accommodation and pupil size have also been noted. Optical coherence tomography allows precise assessment of the anatomic relationship between the ICL and the crystalline lens in a noncontact, noninvasive manner, permitting dynamic monitoring of changes in accommodation and pupil size.