Inzisionale Astigmatismusbeeinflussung bei der Implantation von phaken 6-mm-Irisklauenintraokularlinsen

[Intraocular lens explantation and retroiridal iris claw lens implantation via the pars plana : Video article]

OBJECTIVE OF SURGERY

The aim is the explantation of an intraocular lens (IOL) due to dislocation into the vitreous cavity with subsequent secondary implantation of a retropupillary iris claw IOL via the pars plana without creating a large corneal incision. The aim of the operative technique is to avoid corneal astigmatism after secondary IOL implantation, faster recovery of visual acuity and reduction of invasive maneuvers in the anterior chamber.

INDICATIONS

The surgery is indicated by an in-the-bag dislocation of a posterior chamber lens into the vitreous cavity without the possibility of refixation due to zonulopathy.

CONTRAINDICATIONS

Contraindications are extensive iris stromal defects, iritis, scleromalacia, ischemic retinopathies.

SURGICAL TECHNIQUE

The technique consists of explantation of the IOL during a standard pars plana vitrectomy (20 gauge) with an extended sclerotomy and subsequent secondary implantation of a retropupillary iris claw IOL using the same sclerotomy. The operation video is available online.

FOLLOW-UP

Treatment is carried out with local steroids and antibiotic eyedrops for 3 weeks. In the case of a corneal suture, removal is recommended after 14 days.

EVIDENCE

The implantation of a retroiridal iris claw lens is an established procedure. The introduction via the pars plana in the presented form is a first description.

Phakic iris-claw IOL implantation, with Bursa technique, through a self-sealing scleral tunnel and without iridotomy or iridectomy

PURPOSE

To present a novel technique for the implantation of phakic iris-claw intraocular lenses (IOL) in highly myopic cases.

METHODS

Twelve cases, under the age of 40, with high myopia were included in this retrospective study. The mean follow-up span was 14.4+/-5.8 months. Phakic iris-claw IOL implantation was performed, through a 5.5 or 6.5 mm self sealing scleral tunnel with Bursa technique. No suturing and opening a peripheral iridectomy or iridotomy was required in our study. Pre- and postoperative patient evaluation included manifest and cycloplegic refractions, uncorrected visual acuity, best-corrected visual acuity (BCVA), induced astigmatism, and intraocular pressure (IOP) assessments.

RESULTS

All eyes gained one to nine lines of BCVA of the Snellen chart. The vector analysis revealed an induced astigmatism of 0.63 D. No significant IOP change was detected throughout the follow-up.

CONCLUSIONS

The data suggest that nonfoldable iris fixated phakic IOL implantation, through a self-sealing incision with Bursa technique, is safe and requires no iridectomy or iridotomy in cases with deep anterior chambers.

Behaviour of the phakic iris-claw intraocular lens (Artisan /Verisyse) during accommodation: an optical coherence biometry study

PURPOSE

To evaluate variations in the position of the phakic iris claw lens (Artisan, Verisyse) and the natural crystalline lens during the accommodation process.

METHODS

We measured changes in position of the iris claw lens and the crystalline lens during the accommodation using optical coherence biometry (AC Master/Carl Zeiss Meditec, Germany) in 17 patients (28 eyes) with a phakic iris claw lens implanted for high myopia and/or myopic astigmatism. Accommodative effort was obtained using an internal optical target within the measuring device.

RESULTS

There was a forward shift of the phakic iris claw lens with a mean of 70 microm (8-178 microm) of the optical path length (OPL). At the same time the anterior pole of the natural lens showed a forward mean movement of 85 microm (4- 260 microm).

CONCLUSIONS

An anterior displacement of the iris-claw phakic lens was shown in a series of eyes during the accommodation process. As this displacement goes along with the forward displacement of the anterior pole of the crystalline lens, the preoperative measurement of the latter might provide some additional information about the position of the iris claw lens in the accommodative state after implantation.

[Toric phakic intraocular lenses]

After more than 3 years of follow-up, the satisfactory results achieved with the toric iris-fixated phakic intraocular lens (IOL) mean we can regard implantation of this lens as a procedure with the potential to provide safe, predictable, effective and stable correction of astigmatic errors, providing patients are carefully selected and receive adequate preparation for surgery. The iris-fixated toric phakic IOL (Verisyse, Advanced Medical Optics; Artisan, Ophtec) is a PMMA lens with a total diameter of 8.5 mm and an optic diameter of 5 mm. It has a spherical anterior and a toric posterior surface. Its refractive power ranges from -2 dpt to -21 dpt for myopia and from +2 dpt to +12.5 dpt for the correction of hyperopia. Cylindrical correction is available from 2 dpt to 7.5 dpt. The Visian toric implantable Collamer lens (Staar) differs in that it is foldable and can be inserted through a very small incision of about 2.8 mm. It is placed in front of the natural lens in the ciliary sulcus. The aim of implanting these phakic IOLs is to correct the entire refractive error, meaning both the spherical and the astigmatic error, in a single step. Different lens models are available, and the selection depends on the direction of the cylinder axis and the anatomical situation, among other things.

Klassifikation biomedizinischer Forschungsberichte als Grundlage evidenzbasierter Medizin in der Augenheilkunde

BACKGROUND

Evidence-based medicine requires careful appraisal of published data derived from experimental and clinical studies. Based on classification of biomedical research reports, evidence levels can be determined and recommendations for therapeutic decisions can be made.

METHODS

A classification system for clinical studies was developed. It was evaluated in classifying the reports published in Der Ophthalmologe during 2003-2004 (study design: descriptive cross-sectional study, case series).

RESULTS

In the 2-year interval, 70 longitudinal and 95 cross-sectional studies were published. The vast majority of the longitudinal studies were interventional cohort studies. Not considering case reports, 73% of the original articles were longitudinal prospective studies, 1% were retrospective (case-control) studies, and 26% were cross-sectional studies.

CONCLUSIONS

The study design of all published articles could be classified using the classification system. This classification system proves to be applicable in the context of clinical studies in ophthalmology and may be helpful in the process of critical appraisal of the literature and synthesis of clinical evidence and an evidence-based recommendation.

[Blunt ocular trauma. Part I: blunt anterior segment trauma]

Blunt ocular traumas include contusions and ruptures of the globe--open and closed globe injuries. Characteristic damage results in anterior and posterior segment trauma. Typical patterns of injuries are combinations of (1) hyphema grade II-IV, iris-lens injury, vitreal bleeding--choroidal rupture and increased risk of rebleeding, (2) angle recession >180 degrees--secondary open-angle glaucoma, and (3) vitreal prolapse and lens dislocation-retinal detachment. Patients with blunt eye trauma should be under steady observation by an ophthalmologist to handle late complications.