Biomedical subjects

Berthold Seitz

Publications and source records attributed to Berthold Seitz.

79 records · Page 5Linked to original sources

PubMed2002

Corneal neovascularization after nonmechanical versus mechanical corneal trephination for non-high-risk keratoplasty.

PURPOSE: To analyze the influence of mechanical versus nonmechanical trephination of donor and host corneas on superficial, peripheral corneal neovascularization occurring after non-high-risk keratoplasty. METHODS: Patients of the prospective Erlangen non-high-risk keratoplasty study with standardized corneal photographs taken preoperatively and 1 year later were analyzed (n = 184). Slides of these photographs were projected (magnification x100) and corneal vessels graded in a standardized semiquantitative fashion into five categories with regard to limbus, sutures, and host-graft junction in each of 12 corneal sectors. Degree (total increase of grades in the 12 sectors) and maximal extent of corneal neovascularization (maximal centripetal extension of blood vessels) were analyzed. In 32 patients mechanical (17%) and in 152 nonmechanical trephination of host and donor tissue was performed (193-nm excimer laser, 83%). Statistical analysis was done using Fisher's exact and Mann-Whitney test. RESULTS: Corneal neovascularization within the first postoperative year was lower in the nonmechanical [73 of 152 (48%)] compared with mechanical trephination group [24 of 32 (75%); p< 0.01; Mann-Whitney test]. Maximal extent of neovascularization (i.e., vessels reaching the interface or growing beyond) was not yet significantly different between nonmechanical (8%) and mechanical (17%) trephination (p = 0.074). CONCLUSIONS: Nonmechanical trephination using the 193-nm excimer laser in non-high-risk keratoplasties might reduce corneal neovascularization occurring within the first postoperative year. This indicates that in the non-high-risk setting, development of postoperative corneal neovascularization may be affected by the trephination technique and subsequent wound-healing response.

Aged↗

PubMed2002

Histopathology of corneal changes in lecithin-cholesterol acyltransferase deficiency.

PURPOSE: Lecithin-cholesterol acyltransferase (LCAT) deficiency is a rare entity. This dyslipoproteinemia may lead to corneal opacity, renal failure, and arteriosclerosis. METHODS: Presentation of a 66-year-old man with bilateral corneal opacification due to LCAT deficiency caused by a single-nucleotide exchange in codon 123 of gene. An extracapsular cataract extraction combined with full-thickness corneal transplantation was performed. The corneal specimen was analyzed by light and transmission electron microscopy. RESULTS: All stromal layers showed extracellular vacuoles with acid mucopolysaccharide contents measuring up to 2.5 microm. Amyloid deposits measuring up to 12 microm in diameter were detected in the stroma and especially predescemetally. CONCLUSION: To our knowledge, this is the first histologic description of secondary amyloidosis in a full-thickness corneal specimen with LCAT deficiency. The disease is associated with anemia, proteinuria, a lack of plasma high-density lipoprotein, and the presence of target cells. Bilateral corneal opacification is a characteristic of the disease and may allow early detection of homozygous LCAT deficiency by the ophthalmologist.

Aged↗

PubMedDate not supplied

[Visual acuity and astigmatism after eccentric penetrating keratoplasty - a retrospective study on 117 patients].

PURPOSE: The purpose of this study was to asses the functional results of eccentric homologous penetrating keratoplasty in respect of diagnosis as well as position and size of the corneal graft. PATIENTS AND METHODS: In this retrospective study, visual acuity and astigmatism of 117 cases of a round eccentric homologous penetrating keratoplasty in 91 eyes of 91 patients were analysed. The PK became necessary because of a corneal ulcer (104), 6 eyes with corneal scars and 7 eyes with ectatic corneal diseases. Using 84 postoperative slides the following parameters were quantified: graft diameter and transparency, distance of the geometric centre of the cornea from the central trephination margin (distance) as well as from the geometric centre of the graft (decentration). Seventeen grafts were classified as eccentric peripheral keratoplasty (mean diameter 5.0 +/- 1.7 mm) with the optical axis through the host cornea and 67 as eccentric central keratoplasty (7.0 +/- 1.3 mm) with the optical axis through the graft. RESULTS: The average follow-up period was 25 months. The astigmatism after 3/12/24 months was 6.7/6.3/5.5 D, but was irregular and not measurable in 74 %/52 %/49 %. The astigmatism increased with increasing decentration (24 months, p = 0.04). After 3/12/24 months, the VA in ulcers was 0.1/0.16/0.16, in scars 0.2/0.6/0.5 and in ectatic diseases 0.3/0.5/0.6. The position of graft and the visual acuity did not correlate significantly. After 24 months, larger the graft size was associated with better visual acuity. With increasing decentration the visual acuity decreased (p = 0.02) and was significantly lower (0.15) in the case of - 2.0 < distance < 2.0 mm than in the case of distance > 2.0 mm (0.4; p = 0.01). CONCLUSION: The diagnosis resulting in eccentric penetrating keratoplasty seems to have a major impact on the long-term functional prognosis of visual acuity. In addition, visual acuity is limited by high and often irregular astigmatism. Our results indicate that an increasing decentration of the graft is not invariably associated with decreasing visual acuity, provided the graft-host junction is not located in direct proximity of the optical axis.

Adolescent↗

PubMedDate not supplied

Conoidal fitting of corneal topography height data after excimer laser penetrating keratoplasty.

PURPOSE: To demonstrate a mathematical method for approximation of discrete corneal topography height data with a biconic model surface for better appreciation of the optical performance of the graft after penetrating keratoplasty. METHODS: In this retrospective study we included 50 eyes of 50 patients (30 keratoconus; 20 Fuchs' dystrophy) undergoing nonmechanical excimer laser penetrating keratoplasty. Conventional keratometry, corneal topography (TMS-1), subjective refraction, and best spectacle-corrected visual acuity (BSCVA) were assessed preoperatively, 3 and 6 months postoperatively, and before/after suture removal. A biconic model surface was fitted to the topographic raw data (8.0-mm region of interest) minimizing the root mean square error and a set of parameters (meridional power, axis, conic constant, and approximation error) was determined. The refractive cylinder was correlated with keratometric power readings, the Simulated Keratometry (SimK) of the topography system, and the respective parameters of the model surface. RESULTS: Keratometric/SimK astigmatism increased from preoperatively (3.40/4.30 D) to 3 months (4.30/4.80 D) and decreased to 3.40/3.90 D after suture removal. Refractive cylinder/cylinder of the biconic increased slightly from 2.10/2.60 D preoperatively to 3.20/3.30 D after suture removal. The topographic cylinder SimK yielded the highest and the refractive cylinder the lowest values at each follow-up examination. Central keratometric power readings were stable before suture removal and decreased (about 1 D) due to suture removal. The conic constants in both meridional cross-sections changed from a prolate to a spherical shape in the early time course after penetrating keratoplasty and reconverted to a prolate shape after suture removal. Regarding cylinder axis, there was a significant correlation of the model surface with the refractive cylinder at all examination (P < .05) but only a mild correlation of the keratometric and SimK cylinder axis to the refractive cylinder axis at some examination stages. CONCLUSION: Approximation of corneal topography height data with a biconic model surface renders reconstruction of clinically relevant corneal topography parameters including corneal asphericity with marked data compression. The correlation of amount/axis of refractive cylinder was best represented with the model surface parameters.

Aged↗

PubMedDate not supplied

Implantation of a new accommodative posterior chamber intraocular lens.

PURPOSE: A new, potentially accommodative posterior chamber lens (PCIOL) was designed based on principles elaborated by Hanna using finite element computer simulation methods. We report 3-month postoperative results in patients. METHODS: In a prospective study, 12 eyes of 12 patients (age 45 to 87 yr) underwent phacoemulsification for cataracts and PCIOL implantation. The PCIOL, 1 CU, has haptics designed for anterior optic movement following ciliary muscle contraction. Patients were examined postoperatively after 1 and 2 days, 1, 2 and 6 weeks, and 3 months, and results were compared with a control group of 12 eyes that received standard PMMA or acrylic PCIOLs. RESULTS: Surgery was uncomplicated and all PCIOLs were well-tolerated and stable with good centration in the capsular bag. The results were (mean +/- SD [range] and median; 1 CU versus control PCIOL): near visual acuity (Birkhäuser reading chart at 35 cm) with best distance correction 0.34 +/- 0.17 (0.2 to 0.6), 0.3 (J10-J1, median J7) versus 0.15 +/- 0.07 (0.1 to 0.3), 0.15 (J16-J7, median J13), P=.001; subjective near point 59 +/- 10 cm (40 to 100 cm), 53.5 cm versus 93 +/- 20 cm (64 to 128 cm), 86 cm, P=.004; retinoscopic accommodative range 1.2 +/- 0.4 D (0.63 to 1.5 D), 1.2 D versus 0.2 +/- 0.19 D (-0.25 to 0.5 D), 0.25 D, P < .001; decrease of anterior chamber depth after 2% pilocarpine 0.63 +/- 0.16 mm (0.40 to 0.91 mm), 0.63 mm versus 0.15 +/- 0.05 mm (0.08 to 0.20 mm), 0.17 mm, P < .001. CONCLUSIONS: The new PCIOL appears to be safe at short to medium term. Our results indicate pseudophakic accommodation secondary to focus shift with this PCIOL. Additional larger and long-term studies are necessary for exact evaluation of safety and accommodative power of this new PCIOL.

Accommodation, Ocular↗

PubMedDate not supplied

Flap quality in single versus multiple use of the same blade in the Flapmaker microkeratome.

PURPOSE: We evaluated experimentally the variability of cut thickness, flap diameter, and cut quality produced by the Flapmaker corneal microkeratome (IOLTech), with single and repeated use of the same cutting blade. METHODS: Keratectomy was performed with twelve cutting heads (8.5-mm diameter, 160-microm cutting depth) on 47 corneas and with six cutting heads (8.0-mm diameter, 180-microm cutting depth) on 18 freshly enucleated swine eyes in a repeated manner. Ultrasonic pachymetry was determined at the initial, central, and final microkeratome pass zones, first before the flap was created and subsequently after the flap was reflected. Flap diameter was measured by planimetry. After the procedure stromal portions were submitted for scanning electron microscopy. RESULTS: On the first blade use, mean central flap thickness was 145 +/- 32 microm and mean vertical flap diameter was 8.4 +/- 0.26 mm with the 8.5-mm blades. With the 8.0-mm blades, mean central flap thickness was 155 +/- 23 microm and mean vertical flap diameter was 8.0 +/- 0.27 mm. Scanning electron microscopy disclosed smooth cut surfaces when new blades were used, but with repeated blade use, increasingly prominent stromal bed folds were observed. CONCLUSIONS: The evaluated blades produced reproducible flap size and thickness and good cut quality with single use, but after the first use, cut quality markedly deteriorated. Repeated use of Flapmaker cutting blades is not recommended.

Animals↗

PubMedDate not supplied

Excimer laser phototherapeutic keratectomy for granular and lattice corneal dystrophy: a comparative study.

PURPOSE: To compare the visual and refractive outcome after excimer laser phototherapeutic keratectomy (PTK) for superficial comeal opacities in granular and lattice dystrophy. METHODS: Phototherapeutic keratectomy was performed in 62 eyes of 40 patients (granular dystrophy [n = 50] and lattice dystrophy [n = 12]) after epithelial debridement and pannus removal. Data regarding pre-and postoperative best spectacle-corrected visual acuity, changes in spherical equivalent of manifest refraction, Zeiss keratometry, astigmatism, and corneal topography were analyzed and compared between granular and lattice dystrophy. Recurrence, if any, was noted during a mean follow-up of 3.0 +/- 2.7 years. RESULTS: Best spectacle-corrected visual acuity improved in 79% and 62% of eyes with granular and lattice dystrophy, respectively. Spherical equivalent refraction increased by a mean of 1.3 +/- 1.7 diopters (D) (median: 1.0 D) for granular dystrophy and a mean of 1.0 +/- 1.8 D (median: 0.5 D) for lattice dystrophy. The keratometric central power decreased by a mean of -0.8 +/- 4.3 D (median: -1.6 D) for granular dystrophy and a mean of -0.3 +/- 1.6 D (median: -0.7 D) for lattice dystrophy. No significant changes were noted regarding keratometric astigmatism in either granular or lattice dystrophy. The proportion of "regular" and "mild irregular" keratometry mires increased (39% vs 67% for granular dystrophy and 0% vs 50% for lattice dystrophy). In granular dystrophy, the surface regularity index/surface asymmetry index (SRI/SAI) decreased significantly from 2.14/2.24 preoperatively to 1.31/0.80 postoperatively (P = .006/P = .01). In contrast, decrease of SRI/SAI from 1.97/1.65 preoperatively to 1.35/1.16 postoperatively did not reach statistical significance in lattice dystrophy. Recurrences were observed in 10 (20%) eyes with granular dystrophy and 2 (17%) eyes with lattice dystrophy. CONCLUSIONS: Our results suggest that PTK may be tried in all patients with superficially accentuated opacities in granular and lattice dystrophy before undergoing a more invasive procedure, such as lamellar or penetrating keratoplasty.

Adolescent↗