Biomedical subjects

Christian Simader

Publications and source records attributed to Christian Simader.

8 recordsLinked to original sources

PubMed2006

Retinal pigment epithelium tears following verteporfin therapy combined with intravitreal triamcinolone.

PURPOSE: To detect patients with neovascular age-related macular degeneration (AMD) who experience retinal pigment epithelium tears after initial verteporfin therapy combined with intravitreal triamcinolone during early follow-up. DESIGN: Prospective interventional case series. METHODS: Forty-five consecutive patients with choroidal neovascularization (CNV) in AMD were treated with verteporfin therapy combined with 4 mg of intravitreal triamcinolone. Optical coherence tomography (OCT), visual acuity, and fluorescein angiography were performed. RESULTS: Two eyes with a predominantly classic CNV developed a retinal pigment epithelium tear. An early onset tear could be differentiated from a delayed onset tear. OCT showed an increased depth signal in areas of missing retinal pigment epithelium and a wavy, contracted, and elevated retinal pigment epithelium band. CONCLUSIONS: Retinal pigment epithelium tears can occur despite adding intravitreal triamcinolone to verteporfin therapy. OCT shows characteristic changes in the evolution of retinal pigment epithelium tears after combination therapy.

Choroidal Neovascularization↗

PubMed2006

C-peptide does not affect ocular blood flow in patients with type 1 diabetes.

OBJECTIVE: The aim of the present study was to investigate the effect of intravenous C-peptide infusion on ocular blood flow in patients with type 1 diabetes under euglycemic conditions. RESEARCH DESIGN AND METHODS: The study was performed in a randomized, placebo-controlled, double-masked, two-way, crossover design in 10 type 1 diabetic patients. C-peptide was intravenously administered at two different dosages (dosage 1: 25 pmol . kg(-1) . min(-1) bolus followed by 5 pmol . kg(-1) . min(-1) continuous infusion; dosage 2: six times higher than dosage 1), each for 60 min. Physiologic saline solution was used as a control for C-peptide on a different study day. On both study days, euglycemic clamps were performed. To assess retinal blood flow, laser Doppler velocimetry (blood flow velocities) and retinal vessel analyzer (vessels diameters) measurements were performed. Laser interferometric measurements of fundus pulsation were used to assess pulsatile choroidal blood flow. Blood velocities in the ophthalmic artery were measured using color Doppler imaging. RESULTS: Eight patients (two female and six male) completed the study according to the protocol and without adverse events. One patient developed an anaphylactic reaction to C-peptide, which resolved without sequelae. The following results originate from the remaining eight subjects. Systemic hemodynamic parameters remained stable during both study days. Infusion of C-peptide did not affect any ocular hemodynamic parameter. CONCLUSIONS: The data of the present study indicate that exogenous C-peptide exerts no effect on ocular hemodynamic parameters in type 1 diabetic patients under euglycemic conditions. The maximum detectable change in these parameters was <25%.

Adult↗

PubMed2005

Contrast sensitivity function in eyes with diffractive bifocal intraocular lenses.

PURPOSE: To evaluate the image quality of asymmetric Acri. Twin bifocal intraocular lenses (IOLs) (Acri.Tec) by comparing distance and near black-white contrast sensitivity function with that of the Pharmacia 811E IOL. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: Thirty-two eyes of 16 patients were examined after contralateral implantation of 1 Acri. Twin near-weighted 733D IOL and 1 Acri. Twin distance-weighted 737D IOL. Twenty eyes in 10 patients were examined after binocular Pharmacia 811E IOL implantation. Best corrected distance and near visual acuities were determined. Individual reading distance was recorded and corrected to 40 cm for the near contrast test (Holladay Contrast Acuity Test). Distance contrast sensitivity function was evaluated using the Acuity Max (Science 2020) computer program. RESULTS: Best corrected distance visual acuity was significantly better in patients with the 737D IOL than in those with the 733D or 811E IOLs. For distance reading with best distance correction, the 733D IOL performed better than the 737D and the 811E. Individual reading distance with the Acri. Twin IOL and 811E IOL was 33.6 cm and 34.0 cm, respectively. Best distance-corrected near contrast sensitivity function was better in eyes with the near-weighted 733D IOL. Binocular testing showed a significant difference between the 2 groups only at low-contrast values. At distance, contrast sensitivity function was better with the 737D IOL, whereas no difference was found between the 733D and the 811E IOLs. Binocular contrast sensitivity function at distance revealed statistically significantly better results in the Acri. Twin group. CONCLUSION: An asymmetric diffractive bifocal lens system was advantageous in terms of vision quality when implanted binocularly and superior to monocular stronger weighted focus compared with conventional bifocal IOLs.

Adult↗

PubMed2005

Verteporfin therapy for choroidal hemangioma: a long-term follow-up.

BACKGROUND: To document the long-term follow-up of patients with circumscribed choroidal hemangioma who were treated with verteporfin photodynamic therapy (PDT). METHODS: Fifteen patients were included in a prospective interventional case series. Verteporfin PDT as a bolus infusion of 6 mg/m body surface area and a light dose of 100 J/cm at 689 nm applied over 166 seconds were administered. Standardized evaluation was performed every 3 months within the first year and at 12-month intervals during follow-up. RESULTS: At baseline, all patients presented with significant vision loss ranging from 20/26 to 20/500. During a mean follow-up of 36.6 months (range, 12-66 months), no patient had evidence of recurrence. Mean final visual acuity ranged from 20/20 to 20/400. In all patients, complete and permanent regression with no signs of tumor regrowth or recurring subretinal fluid was found. Of 15 patients, 13 had a substantial increase in visual acuity (range, 2-9 lines), and 2 patients' visual acuity remained stable. Chorioretinal atrophy at the previous tumor site did not enlarge over time. Retreatments after completion of the primary treatment were not necessary. CONCLUSION: Persistent and complete absence of choroidal hemangioma associated with persistent improvement in visual acuity and central visual fields can be obtained with verteporfin PDT.

Choroid Neoplasms↗

PubMed2005

Short-term increase of intraocular pressure does not alter the response of retinal and optic nerve head blood flow to flicker stimulation.

PURPOSE: It has been shown that stimulation with diffuse luminance flicker induces vasodilatation in the human retina and increases optic nerve head (ONH) blood flow. The present study was designed to investigate the influence of a short-term increase in intraocular pressure on flicker-induced changes in ONH blood flow and retinal vessel diameters. METHODS: In a group of 15 healthy volunteers, IOP was increased by the episcleral suction cup technique. ONH blood flow was assessed with a laser Doppler flowmeter, and retinal vessel diameters were measured with the retinal vessel analyzer. Flicker responses of retinal vessel diameters and ONH blood flow were determined at baseline conditions and during suction of 70 and 140 mm Hg. Flicker light consisted of 8-Hz square-wave flashes at a wavelength below 550 nm and produced a retinal irradiance of 140 muW/cm(2). RESULTS: Suction increased IOP from 12 +/- 2 to 27 +/- 4 mm Hg and 43 +/- 4 mm Hg. Stimulation with diffuse luminance flicker induced an increase in ONH blood flow of +24.0% +/- 20.7%. Increased IOP did not significantly change the flicker response in the ONH (+19.3% +/- 26.6% and +22.1% +/- 25.1%). In retinal veins, flicker induced an increase in vessel diameter of +3.0% +/- 2.0%. Flicker responses in retinal veins were not significantly altered after the IOP was increased, compared with those recorded at baseline IOP (+2.8% +/- 2.5% and +3.2% +/- 2.2%). The flicker response in retinal arteries at baseline IOP was +3.5% +/- 2.0%. Again, the increase in IOP did not significantly alter this flicker response (+2.8% +/- 1.6% and +3.1% +/- 2.4%). CONCLUSIONS: A short-term increase in IOP does not alter the response of retinal vessel diameters and ONH blood flow to diffuse luminance flicker, which indicates that increased IOP does not alter retinal or ONH regulation during neuronal stimulation.

Blood Flow Velocity↗

PubMed2004

Influence of spectacle-related changes in retinal image size on contrast sensitivity function after laser in situ keratomileusis.

PURPOSE: To evaluate changes in contrast sensitivity after laser in situ keratomileusis (LASIK) for the correction of myopia using a monitor-based method and considering the preoperative minification effect of high-diopter spectacles. SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: Fifteen eyes of 11 patients had LASIK to correct myopia. The best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) were measured preoperatively and 1, 3, and 6 months postoperatively using the AcuityMax (Science 2020) computer program. The error in contrast sensitivity measurement due to different angular sizes of the test figures deriving from the spectacle refractions before and after LASIK were considered. RESULTS: Preoperatively, and at 1, 3, and 6 months, the mean Snellen BCVA was 0.93 +/- 0.19 (SD), 0.80 +/- 0.26, 0.85 +/- 0.21, and 0.84 +/- 0.27, respectively. The best mean CS (measured at 1.1 logMAR) was 1.17 +/- 0.05, 1.12 +/- 0.07, 1.13 +/- 0.08, and 1.18 +/- 0.04, respectively. The strongest CS changes were observed at 0.7 logMAR (6 cycles per degree), where CS was 1.10 +/- 0.07 preoperatively and 1.06 +/- 0.09, 1.07 +/- 0.12, and 1.14 +/- 0.07, at 1 month, 3 months, and 6 months, respectively. With correction for the spectacle effect, the preoperative CS was approximately 3% higher and CS at 3 months for intermediate optotype sizes was significantly inferior to preoperatively. CONCLUSIONS: With correction of different retinal image sizes before and after LASIK (due to different spectacle refraction), the CS was significantly below the preoperative values at 1 and 3 months and approached the preoperative values at 6 months. The proposed method is potentially capable of quality monitoring and method comparisons after photorefractive surgery.

Adult↗

PubMed2004

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

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.

Adult↗

PubMed2003

Glare and halo phenomena after laser in situ keratomileusis.

PURPOSE: To simulate and measure subjectively observed glare and halos after laser in situ keratomileusis (LASIK). SETTING: University of Vienna, Medical School, Department of Ophthalmology, Vienna, Austria. METHODS: In 16 eyes of 10 patients, the best corrected visual acuity (BCVA) and subjectively observed glare and halo size under mesopic conditions were measured before LASIK and 1, 3, and 6 months postoperatively. Infrared pupillography was used to ensure that all patients had a larger ablation zone than the measured pupil size under mesopic conditions. RESULTS: Preoperatively, the mean Snellen BCVA was 0.88 +/- 0.17 (SD) and the mean glare and halo size was 1.97 +/- 1.20 square degrees (sqd) before the treatment. One month after LASIK, the BCVA was 0.83 +/- 0.29 and the mean glare and halo size, 2.61 +/- 3.14 sqd. Three months after LASIK, the mean values were 0.90 +/- 0.26 and 1.88 +/- 2.37 sqd, respectively. Six months after LASIK treatment, they were 0.85 +/- 0.28 and 1.30 +/- 1.63 sqd, respectively. The 95% confidence interval for the difference between preoperative glare and halo and glare and halo at 6 months was -1.56 to + 0.51 sqd. CONCLUSIONS: Subjectively observed glare and halo size after LASIK reached a peak after 1 month and decreased in the following postoperative period.

Adult↗