Posterior capsule opacification.

Purpose To prove the long-term dampening effect of riboflavin- and ultraviolet-A-induced collagen crosslinking on progressive keratoconus. Setting Department of Ophthalmology, C.G. Carus University Hospital, Dresden, Germany. Methods Four hundred eighty eyes of 272 patients with progressive keratoconus were included in this long-term retrospective study. The maximum follow-up was 6 years. At the first and all follow-up examinations, refraction, best corrected visual acuity (BCVA), corneal topography, corneal thickness, and intraocular pressure were recorded. Results The analysis included 241 eyes with a minimum follow-up of 6 months. The steepening decreased significantly by 2.68 diopters (D) in the first year, 2.21 D in the second year, and 4.84 D in the third year. The BCVA improved significantly (≥1 line) in 53% of 142 eyes in the first year, 57% of 66 eyes in the second year, and 58% of 33 eyes in the first year or remained stable (no lines lost) in 20%, 24%, and 29%, respectively. Two patients had continuous progression of keratoconus and had repeat crosslinking procedures. Conclusions Despite the low number of patients with a follow-up longer than 3 years, results indicate long-term stabilization and improvement after collagen crosslinking. Thus, collagen crosslinking is an effective therapeutical option for progressive keratoconus.

Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results.

Induction of cross-links in corneal tissue.

In the past two decades, optical coherence tomography (OCT) has been established as an adjunct diagnostic technique for noninvasive, high-resolution, cross-sectional imaging in a variety of medical fields. The rapid development of ultrabroad bandwidth light sources has recently enabled a significant improvement in OCT imaging resolution, demonstrating the potential of OCT to accomplish its original goal of performing noninvasive optical biopsies, i.e., the in vivo visualization of microstructural morphology in situ, which had previously only been possible with histopathology. In addition, these novel light sources might also enable the use of spectroscopic OCT, an extension of ultrahigh-resolution OCT, for enhancing image contrast as well as detecting spatially resolved functional, biochemical tissue information. State-of-the-art-light sources that now permit ultrahigh-resolution OCT covering the whole wavelength region from 500 to 1600 nm are reviewed and fundamental limitations of OCT image resolution are discussed. Ex vivo ultrahigh-resolution OCT tomograms are compared with histological results; first clinical in vivo ultrahigh-resolution OCT and preliminary spectroscopic OCT results are presented and their impact for future clinical and research applications is discussed.

Ultrahigh Resolution Optical Coherence Tomography

We present a polarization-sensitive optical coherence-domain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample. The device is insensitive to the rotation of the sample in the plane perpendicular to ranging. Phase measurement accuracy is ±0.86°, but the reflectometer can distinguish local variations in birefringence as small as 0.05° with a distance resolution of 10.8 μm and a dynamic range of 90 dB. Birefringence-sensitive ranging in a wave plate, an electro-optic modulator, and a calf coronary artery is demonstrated.

Polarization-sensitive low-coherence reflectometer for birefringence characterization and ranging

Purpose. The purpose of this study was to compare central corneal thickness (CCT) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus) with scanning slit topography (Orbscan; Bausch & Lomb), and with ultrasound pachymetry (SP-2000; Tomey). Methods. CCT in 30 healthy eyes was measured twice with each modality by 2 independent observers in random order. The results from scanning slit topography are given both with and without multiplication with the acoustic correction factor of 0.92. In addition, the displayed images from the rotating Scheimpflug camera and scanning slit topography were used to calculate the signal difference-to-noise ratios (SD/N) between cornea and background signal. Results. The mean CCT values as determined with the different modalities ( standard deviation) were: 542 29 m, 576 37 m, 530 34 m, and 552 32 m for rotating Scheimpflug imaging, for uncorrected and for corrected scanning slit pachymetry, and for ultrasound, respectively. The differences between modalities ( 95% limits of agreement) were -9.8 31 m between rotating Scheimpflug and ultrasound, 24 31.2 m between scanning slit and ultrasound, and 33 27 m between scanning slit and rotating Scheimpflug imaging. The limits of agreement for within and between observer effects were within 4.2% of the absolute CCT values for scanning slit and ultrasound and within 2.2% for the rotating Scheimpflug imaging. The rotating Scheimpflug camera showed similar SD/N ratios but steeper edges of the corneal surfaces in the intensity profile plots. Conclusion. In the assessment of normal corneas, the Pentacam measured CCT values closer to ultrasound pachymetry and with less variability compared with Orbscan. The (interobserver) reproducibility with the Pentacam was highest of all 3 modalities. (Optom Vis Sci 2005;82:892-899)

Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound.

Purpose To determine the efficacy and rotational stability of a toric posterior chamber silicone intraocular lens (IOL) to correct preoperative astigmatism in cataract patients. Setting Department of Ophthalmology, University Hospital of Vienna, Vienna Austria. Methods Between 1993 and 1998, foldable toric single-piece plate-haptic silicone IOLs were implanted in 37 eyes (30 patients). The cylindrical IOL power was 2.00 diopters (D) (n = 29), 3.50 D (n = 7), or 4.00 D (n = 1). Phacoemulsification was performed through a scleral or a corneal sutureless self-sealing incision. Outcomes of Snellen visual acuity (without, with spherical, and with best correction), refractive and keratometric astigmatism, and IOL rotation after early postoperative (mean 15.9 days ± 10.1 [SD]) and long-term (mean 20.3 ± 16.6 months) follow-ups were evaluated. Results At last follow-up, 31 eyes (83.8%) had a spherically corrected and 34 (91.9%) a best corrected visual acuity of 0.5 (20/40) or better. Mean preoperative refractive and keratometric astigmatism was 2.68 and 2.70 D, respectively. At the last postoperative follow-up, mean refractive astigmatism was reduced to 0.84 D; keratometric astigmatism was 2.30 D. In 7 eyes (18.9%), the IOL axis was rotated a maximum of 25 degrees. In all 37 eyes, the axis of the toric IOL remained within 30 degrees of rotation. Conclusion Early postoperative and long-term follow-ups showed effective and stable correction of astigmatism after implantation of a foldable toric posterior chamber silicone IOL.

Astigmatism correction with a foldable toric intraocular lens in cataract patients.

AIMS To calculate the diameter of halos perceived by patients with multifocal intraocular lenses (IOLs) and to stimulate halos in patients with refractive multifocal IOLs in a clinical experiment. METHODS Calculations were done to show the diameter of halos in the case of the bifocal intraocular lens. 24 patients with a refractive multifocal IOLs and five patients with a monofocal IOL were asked about their subjective observation of halos and were included in a clinical experiment using a computer program (Glare & Halo, FW Fitzke and C Lohmann, Tomey AG) which simulates a light source of 0.15 square degrees (sq deg) in order to stimulate and measure halos. Halo testing took place monoculary, under mesopic conditions through the distance and the near focus of the multifocal lens and through the focus of the monofocal lens. RESULTS The halo diameter depends on the pupil diameter, the refractive power of the cornea, and distance focus of the multifocal IOL as well as the additional lens power for the near focus. 23 out of 24 patients with a refractive multifocal IOL described halos at night when looking at a bright light source. Only one patient was disturbed by the appearance of halos. Under test conditions, halos were detected in all patients with a refractive multifocal IOL. The halo area testing through the distance focus was 1.05 sq deg ± 0.41, through the near focus 1.07 sq deg ± 0.49 and in the monofocal lens 0.26 sq deg ± 0.13. CONCLUSIONS Under high contrast conditions halos can be stimulated in all patients with multifocal intraocular lenses. The halo size using the distance or the near focus is identical.

https://bjo.bmj.com/content/bjophthalmol/85/7/816.full.pdf

Halo size under distance and near conditions in refractive multifocal intraocular lenses

:Purpose.The purpose of this study was to determine the validity and repeatability of anterior chamber depth (ACD) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus Optikgerate GmbH, Wetzlar, Germany) to scanning slit topography (Orbscan; Bausch & Lomb, Rochest

/pdf/validity-and-repeatability-of-anterior-chamber-depth-2hlsmhdrep.pdf

Validity and Repeatability of Anterior Chamber Depth Measurements With Pentacam and Orbscan

Purpose: To study the incidence and progression of lens opacification after implantation of phakic posterior chamber intraocular lenses for myopia and its correlation with vaulting and endothelial cell density (ECD). Setting: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. Methods: An implantable contact lens (ICL V4, Staar Surgical Inc.) was inserted in 76 myopic eyes. Patients were prospectively followed preoperatively and at 1, 3, 6, 12, 24, and 36 months. The uncorrected visual acuity and best corrected visual acuity (BCVA) were determined. Vaulting was measured optically with a Jaeger II pachymeter, and the crystalline lens was examined at the slitlamp for the presence and characteristics of opacification. Endothelial cell morphometry was performed by specular microscopy, and the ECD was calculated. Eyes in which lens opacification developed were followed for at least 12 months to determine the degree and course of visual impairment. Results: Lens opacification occurred in 11 eyes (14.5%). Opacification was correlated with intraoperative trauma to the crystalline lens, age older than 50 years, and decreased ECD values throughout the observation period. Vaulting of the ICL did not correlate with the risk for lens opacification. After onset of lens opacification, 6 eyes (55%) had a stable BCVA within ±0.5 lines and 5 eyes had progressive opacification, losing between 3.5 lines and 0.5 lines (mean 1.8 lines ± 1.1 [SD]). Three eyes (3.9%) in the progressive group had a 1- to 2-line loss of BCVA over preoperative values and subsequently had cataract surgery. Conclusions: Risk factors for lens opacification after implantation of the model V4 ICL included intraoperative trauma to the crystalline lens and older age. Decreased ECD in eyes with opacification suggests ongoing inflammation as a cause. Patients younger than 45 years may have a significantly lower incidence of opacification.

Christian Skorpik

Papers

Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound.

Astigmatism correction with a foldable toric intraocular lens in cataract patients.

Halo size under distance and near conditions in refractive multifocal intraocular lenses

Validity and Repeatability of Anterior Chamber Depth Measurements With Pentacam and Orbscan

Long-term results of implantation of phakic posterior chamber intraocular lenses