[Ultrasound biomicroscopy of posterior chamber phakic intraocular lenses: a comparative study between ICL and PRL models]

Analysis of intraocular positions of posterior implantable collamer lens by full-scale ultrasound biomicroscopy

Background

To analyze the positions of intraocular posterior Implantable Collamer Lens (ICL) and its possible relationship with vault.

Methods

This cross-sectional study included 72 patients with high myopia (134 eyes) who were followed up after phakic intraocular lens implantation. The postoperative time ranged from 1 week to 7 years. We obtained the images of ICL by using Compact Touch STS UBM and observed the position of ICL in posterior chamber and ciliary sulcus. The horizontal lines vault was measured and recorded.

Results

There were various positions in the posterior chamber as observed by full-scale ultrasound biomicroscopy and the haptics were inserted at different positions. -Eight seven eyes (64.9%) that obtained ideal vault, 29 eyes (21.6%) had insufficient vaults and 18 eyes (13.4%) had excessive vault. The vault with various positions of haptics was in ideal range (250 μm–750 μm) almost in each group. Three eyes in this study with haptics on the top of ciliary sulcus obtained excessive vault (mean vault, 850.00 ± 70.71 μm) and one eye appeared one side haptics pushing forward the iris. Among five eyes (3.7%) with iridociliary body cysts, three eyes (60%) obtained ideal vault. One eye (0.7%) with ICL decentralization after implantation surgery had an ideal vault, but the patient had serious glare.

Conclusions

Though ICL in the posterior chamber had different positions and the haptics in most cases were not in the ciliary sulcus, the postoperative vault was almost in the ideal range.

In Vivo Positional Analysis of Implantable Collamer Lens Using Ultrasound Biomicroscopy

Purpose. To evaluate the anterior segment, the anatomical position of the implantable collamer lenses (ICL), and its relationship to adjacent ocular structures using Ultrasound Biomicroscopy (UBM). Methods. In a prospective study, 142 myopic eyes of 93 patients implanted with Visian ICL were subjected to UBM examination between March 2010 and January 2015. The relative position of ICL to the adjacent structure and the overall iris configuration were evaluated. The machine calibers were used to measure the minimum central distance between the ICL and anterior lens capsule (vault) and the vertical central distance between the corneal endothelium and the ICL (E-ICL). Results. The mean ICL vault was 376 ± 105 μm. The mean E-ICL was 2826 ± 331 μm. Contact between ICL and the posterior epithelium of the iris was present in all eyes. The overall iris configuration was flat in 89 eyes. Central anterior convexity was present in 41 eyes and mild peripheral iris bombe in 12 eyes. The haptics could be imaged in the ciliary sulcus in 112 eyes and at least one haptic resting on the lens periphery and zonules in 30 eyes. Conclusion. UBM can provide valuable anatomical information that allows detailed postoperative in vivo assessment of ICL.

The posterior chamber phakic refractive lens (PRL): a review

Implantation of phakic intraocular lenses (pIOLs) is a reversible refractive procedure, preserving the patient's accommodative function with minimal induction of higher order aberrations compared with corneal photoablative procedures. Despite this, as an intraocular procedure, it has potential risks such as cataracts, chronic uveitis, pupil ovalization, corneal endothelial cell loss, pigmentary dispersion syndrome, pupillary block glaucoma, astigmatism, or endophthalmitis. Currently, only two models of posterior chamber pIOLs are commercially available, the implantable collammer lens (STAAR Surgical Co.) and the phakic refractive lens (PRL; Zeiss Meditec). The number of published reports on the latter is very low, and some concerns still remain about its long-term safety. The present article reviews the published literature on the outcomes after PRL implantation in order to provide a general overview and evaluate its real potential as a surgical refractive option.

Preliminary in vivo positional analysis of a posterior chamber phakic intraocular lens by optical coherence tomography and its correlation with clinical outcomes

Purpose

To analyze by spectral-domain optical coherence tomography the anatomical relationship of a specific type of posterior chamber phakic intraocular lens (pIOL) implanted in cases of high to moderate myopia with the adjacent intraocular structures and to correlate it with clinical outcomes.

Methods

Prospective observational case series including 18 eyes with high to moderate myopia (spherical equivalent between −5.88 and −15.75 D) of 9 patients (age range, 29–49 years) undergoing bilateral Phakic Refractive Lens (PRL, Zeiss) implantation. Postoperative visual acuity, refraction, contrast sensitivity (CS), and ocular higher order aberrations (HOA) were evaluated. Furthermore, the in vivo position of the PRL was analyzed by means of spectral domain optical coherence tomography (3D OCT-1000, Topcon). Central (CENV), temporal (TEMV) and nasal vault (NASV) were measured. Correlation of these anatomical parameters with clinical data was also investigated. Mean follow-up was 47 ± 25 months.

Results

A statistically significant visual and refractive improvement (p < 0.01) was found postoperatively. Mean postoperative CENV, NASV, and TEMV were 157.88 ± 69.93 μm, 168.29 ± 65.02 μm, and 188.59 ± 55.99 μm, respectively. Significant difference was found between NASV and TEMV (p = 0.01). No significant correlations were found between ocular aberrometric and anatomical parameters (p ≥ 0.12). CENV, NASV and TEMV correlated significantly with 6-cycles per degree (cpd) photopic CS as well as with 18-cpd low mesopic CS (r ≥ 0.57, p ≤ 0.04). Furthermore, NASV also correlated significantly with preoperative anterior chamber depth (r = −0.65, p = 0.01).

Conclusions

This posterior chamber pIOL shows a trend to nasal position, with potential impact on refractive and visual outcomes, particularly in eyes with deep anterior chambers.

Ultrasound biomicroscopy characterization of acrylic, silicone, and polymethyl methacrylate lenses in vitro

BACKGROUND

This study aims to characterize the reflective properties of some commonly used intraocular lenses (IOLs) in vitro, with a particular focus on lens haptics.

METHODS

Six different types of IOLs, representative of silicone, acrylic, and polymethyl methacrylate (PMMA), single, multipiece, and multifocal were imaged using high-resolution ultrasound biomicroscopy (UBM).

RESULTS

Reflectivity patterns were distinct to the material that was being imaged irrespective of whether the part being imaged was the haptic or optic. Acrylic haptics demonstrated a single "tram-track" reduplication echo, whereas PMMA haptics showed multiple reverberation echoes off the posterior surface. The optics of various PMMA and acrylic lenses demonstrated a reflectivity pattern similar to the respective haptics made of the same material. Silicone optics displayed clear delineation with no reverberation. Both acrylic and silicone material was relatively less reflective when compared with PMMA.

INTERPRETATION

With UBM imaging, the haptics of acrylic and PMMA IOLs demonstrate unique reflective patterns, depending on the material being studied. Prior knowledge of what the lens haptics and optics look like in vitro provides information that may assist in identifying and localizing misplaced intraocular lenses in vivo.

Implants phakes de chambre antérieure versus chambre postérieure

At a time when some of the limitations of photoablation have been defined, such as worry concerning secondary ectasia, a renewed interest in phakic implantation has arisen. This is driven by the goal of avoiding correcting high ametropia with LASIK and is based on the development of soft foldable biomaterials. When all phakic IOLs are in front of the natural lens, two varieties of lenses can be distinguished, depending on whether it is located in the anterior or posterior chamber. The various models available in 2006 and those under current evaluation are reviewed. We do not report details of clinical studies that vary in cohort size and follow-up. The advantages and limitations are discussed for each type of phakic IOL. Adequate although not exclusive indications are deduced. There is no phakic lens that has proved to be superior to the others in terms of safety. All have the ability to provide a visual benefit with a gain in best corrected visual acuity. The difference is based on anatomical effects, requiring long-term follow-up in the evaluation of angles, lens, iris, and endothelium.