Cataract surgery is considered to be the most successful surgery worldwide. However, new developments are ongoing
either to improve the surgical stress or to improve the surgical outcome. While restoration of the transparency and
optical parameters of the eye were initially the first goals, the need to improve the quality of sight (QOS) and to restore
accommodation became evident during the last decades.
By introducing the bag-in-the-lens (BIL) intraocular lens (IOL) and technique of implantation (US Patent 6,027,531)
in 2000, PCO was no longer a matter of concern. Clinical studies conducted between 2000 and 2004 proved the efficacy
of this new IOL with respect to PCO control, but showed additional advantages like surgeon-controlled centration and
rotational stability.
Surgeon-controlled IOL centration based on the alignment of the first and third Purkinje reflexes is one method to
promote IOL centration but future tracking devices will probably enhance the precision by which IOL centration along
the line of sight can be achieved.
Optimal alignment is a major issue if toric correction and compensation of the spherical aberrations is intended to be
incorporated into the IOL optic.
IOL optics with toric correction to compensate for regular astigmatism are in development now, but toric correction
for irregular astigmatism remains extremely challenging for the manufacturers.
Improving the quality of the image by compensating for the spherical aberrations is the next step on our research
programme. The BIL offers some opportunities to optimize postoperative accommodation by introducing the capsular
accommodation ring.
We present a new technique, scanning laser retinoscopy, to spatially resolve in two dimensions the optical aberrations and refractive power of the ocular media. For this purpose, the Maxwellian view of a confocal scanning laser ophthalmoscope (SLO) is configured to scan simultaneously the posterior and the anterior segment of the eye at different levels of prefocussing. This set-up allows retinal imaging and psychophysics through different optical zones of the cornea and lens. In addition, the size of the anatomical pupil can be dynamically controlled by adjusting the colinear infrared and visible light intensities of the illuminating system. In retinoscopic images we can see a part of the retina superimposed by distinctive patterns of shadows in the pupillary area. The variable patterns of shadows in the retinoscopic images change with the level of prefocussing of the SLO. The patterns are the result of local variations in refraction or wavefront aberrations within the lens and cornea. In cases of excimer laser refractive surgery, for example, scanning laser retinoscopy is able to distinguish between a treated central area, transition zone and peripheral cornea. As a corollary, we can document differences between excimer laser delivery systems and also correlate the retinoscopic images with the subjective complaints of refractive surgery patients. These include monocular diplopia, glare, loss of contrast sensitivity besides reduced visual acuity.
Treatment of peripheral post-mortem human corneas with the Holmium laser in a ring pattern resulted in opaque spots. One pair of treated eyes was immediately processed for light and electron microscopy and three other treated eyes were preserved for 4 days in medium in order to compare direct and short-term effects of the Holmium laser. Cross as well as frontal light microscopical sections of all eyes revealed interconnecting bands between the spots. At the ultrastructural level the anterior corneal tissue within these spots was characterized by coagulation of cells and collagen and shoed either a dramatic distorting effect on the epithelium in the eyes processed immediately or a single layer of flattened multi-nucleolated epithelial cells having more than one nucleolus per nucleus in the eyes stored in medium. Furthermore, the spots showed disturbed Bowman's layer, destroyed keratocytes and collagen fibrils which were either coagulated or organized chaotically. The interconnecting bands contained alternating normal and coagulated collagen fibers. The rest of the cornea outside the spots had a normal appearance. In corneas stored in medium, both keratocytes and epithelial cells over the entire cornea exhibited accumulations of cytoplasmic fibrils and glycogen particles. These phenomena were not observed in non-preserved corneas, suggesting that the differences are due to preservation and not due to the laser treatment. It is concluded that morphological changes occur mainly in the treated peripheral cornea whereas the central untreated cornea remains unaffected,indicating that the Holmium laser is a reliable instrument to treat hypermetropic patients.
The aim of this study was to evaluate the implication of the mechanical factor 'decentration' on the visual outcome after PRK. 100 eyes of 70 patients were included. The mean decentration was 0.27 mm +/- 0.18. Decentration was less than 0.5 mm in 84 percent of the cases. The importance of the decentration was investigated by the statistical correlation of decentration from the pupilcenter and the visual outcome. We did not find any statistical significant association for decentrations less than 1 mm. Our conclusion is that decentration, if less than 1 mm, does not play an important role in the final visual outcome after PRK.
Until recently, surgical correction of hyperopia was subject to nearly total regression regardless of the method used. Laser thermokeratoplasty (LTK) with the holmium:YAG laser (Sunrise Technologies' Corneal Shaping System) is able to correct hyperopia in the range of + 1.0 to + 3.0 diopters. Up to eight spots with a spot size of 650 micrometers can be delivered simultaneously. According to the amount of hyperopia to be corrected, eight or sixteen spots are administered with respective pattern diameters of six or six and seven mm. The energy density used is 8.5 J/cm2 per spot. Most of the regression occurs within the first month. In the 30 eyes with a follow-up of 6 months patient satisfaction rate is high and complications are minimal.
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