Biomedical subjects

B Seitz

Publications and source records attributed to B Seitz.

At least 37 records · Page 2Linked to original sources

PubMed2004

[Functional outcomes after penetrating keratoplasty in pseudoexfoliation syndrome (PEX)-keratopathy].

PURPOSE: Keratopathy in pseudoexfoliation syndrome (PEX-keratopathy) is a particular form of corneal endothelial decompensation, which requires a penetrating keratoplasty (PK) for visual rehabilitation at advanced states. The aim of this study was to evaluate the functional outcome and the development of intraocular pressure (IOP) after PK in patients with PEX-keratopathy depending on the presence of pre-existing glaucoma. PATIENTS AND METHODS: This retrospective study included 21 eyes of 21 patients (age 78.6 +/- 7.5 years) with a mean postoperative follow-up of 1.8 +/- 2.2 (median 2) years. The diagnosis of PEX-keratopathy was confirmed clinically as well as by electron microscopy. The recipient and donor trephinations were performed from the epithelial side using an 193 nm excimer laser (n = 11) or mechanically (n = 10). An iridotomy was performed routinely during PK. The postoperative treatment with topical steroid was standardized. RESULTS: Preoperatively, a secondary open-angle glaucoma (SOAG) with optic nerve damage was diagnosed in 11 patients (52 %). Topical antiglaucomatous treatment was needed in 81 % of patients with SOAG. Six weeks postoperatively, patients with SOAG showed a higher prevalence of increased intraocular pressure (IOP) and/or antiglaucomatous treatment compared to patients without SOAG (45 % vs. 20 %). Most of the mild-early intraocular pressure elevations were controlled in both groups during the follow-up. From one year post-PK, there was an increased need for topical antiglaucomatous treatment in both patient groups. In all eyes the IOP was controlled by topical antiglaucomatous treatment. Preoperatively, visual acuity was comparable in patients with and without SOAG (0.06 +/- 0.09 vs. 0.08 +/- 0.1, p = 0.7), but increased significantly more in patients without SOAG (0.38 +/- 0.1, median 0.4) than in patients with SOAG (0.2 +/- 0.1, median 0.2; p = 0.01) after PK. Visual acuity remained stable in both groups throughout the follow-up period. During follow-up only one eye developed an episode of reversible endothelial graft rejection 18 months postoperatively. An irreversible graft failure was seen in none of the patients. CONCLUSION: The functional outcome after PK in PEX-keratopathy seems to be strongly associated with pre-existing SOAG. Patients without SOAG may expect good visual rehabilitation without persistent postoperative IOP increases. However, patients should be followed-up for a prolonged period of time, because from 1 year following PK the need for topical antiglaucomatous treatment increased significantly.

Aged↗

PubMed2004

Q-switched erbium:YAG laser corneal trephination: thermal damage in corneal stroma and cut regularity of nonmechanical Q-switched erbium:YAG laser corneal trephination for penetrating keratoplasty.

PURPOSE: To assess stromal thermal damage and cut regularity induced by nonmechanical Q-switched Er:YAG laser corneal trephination for penetrating keratoplasty. METHODS: Corneal trephination was performed in 80 enucleated porcine eyes by Q-switched (2.94-microm) Er:YAG laser, along with donor and recipient masks made of metal or ceramic. All combinations of 0.65- or 0.96-mm spot diameter and 45- or 50-mJ/pulse energy setting were used with each of the masks at a 5-Hz repetition rate. Corneas were processed for histologic examinations. Stromal thermal damage was quantified on PAS-stained slides, and cut regularity was assessed semiquantitatively on a scale from 0 (regular) to 3 (highly irregular). Transmission electron microscopy and scanning electron microscopy were performed on selected specimens. RESULTS: The least thermal damage (mean +/- SD = 6.2 +/- 0.7 microm) was found in the donor ceramic group with 50-mJ/pulse energy and 0.65-mm spot diameter, while the best regularity of the cut (1.2 +/- 0.4) was found in the donor ceramic group with 45-mJ pulse energy and 0.65-mm spot diameter. Thermal damage was less pronounced in donor than in recipient corneas (P < 0.01). Smaller spot diameter (0.65 mm) led to less thermal damage (P < 0.01) than the use of a 0.96-mm spot diameter. The differences in thermal damage between ceramic and metal masks were minimal. CONCLUSIONS: After Q-switched Er:YAG laser corneal trephination for nonmechanical penetrating keratoplasty, reproducible high cut regularity and low concomitant thermal damage were observed. This is an encouraging finding in the search for a nonmechanical trephine for penetrating keratoplasty combining high precision and low cost.

Animals↗

PubMed2003

[Gene expression in keratoconus. Initial results using DNA microarrays].

INTRODUCTION: Keratoconus is a non-inflammatory ocular disease characterised by conical deformation, progressive thinning and scarring of the central cornea. Despite intensive investigations, the exact cause of the disease still remains unclear. Clinical studies provide strong indications of a major genetic role in the aetiology. We set out to examine the involvement in the manifestation of keratoconus of any of the 5,600 gene specificities available on the Affymetrix GeneChip HuGeneFL. METHODS: After examination of two corneas they were stored in RNAlater, RNA was extracted and hybridised on the chips. Using a combination of dyes it was possible to read the chips with laser detection and to visualise the gene expression pattern. RESULTS: We found an upregulation of collagens, versican, metalloproteinases and cell adhesion proteins. A downregulation was observed for TIGR protein, cytokeratins, eyes absent homologue (Eab1) and the proteins for radical treatment selenoprotein P and monooxygenase. CONCLUSIONS: Our results indicate that keratoconus is a process in which repair and scar-formation mechanisms operate at the same time. As candidate genes for this mechanism, collagen IV and related proteoglycans were favoured.

Cicatrix↗

PubMed2003

[Impact of an Er:YAG laser beam control on cut quality of non-mechanical corneal trepanation for penetrating keratoplasty].

BACKGROUND: Results of non-mechanical corneal trepanation using the excimer laser enhance the morphological and functional results for penetrating keratoplasty. Searching for alternative laser sources we assessed the impact of an automatic laser beam control for the Er:YAG solid-state laser on the cut performance and thermal damage zone in non-mechanical corneal trepanation. METHODS: We compared the cut quality of A) a manually guided laser beam, B) a semiautomatically guided laser beam and C) a fully PC-controlled laser beam positioning system (q-switched, repetition rate 5 Hz, pulse energy 65 mJ, spot size 0.7 mm) along slit aperture masks on 28 rabbit eyes using macroscopic images and histological sections (PAS staining). RESULTS: The manually guided laser beam control (A) induced the broadest thermal damage zone in the corneal stroma (19.3+/-8.7 microm) compared to the semi-automatic mode (B) (8.8+/-3.0 microm, p=0.03) and the PC-controlled laser beam control (C) (7.0+/-3.0 microm, p=0.016). CONCLUSION: The fully automatic PC-controlled laser beam positioning system for the Er:YAG solid-state laser with a small spot size and fixed low repetition rate allows a precise laser beam guidance and a significant enhancement of the cut performance compared to a manual laser beam control via micromanipulator in experimental nonmechanical corneal trepanation.

Animals↗

PubMed2003

[Angiogenesis and lymphangiogenesis in the cornea. Pathogenesis, clinical implications and treatment options].

BACKGROUND: Whereas the normal cornea is devoid of blood and lymphatic vessels,both can invade the cornea secondary to a variety of corneal diseases and after surgery. This not only reduces visual acuity, but also renders such a cornea high-risk, if subsequent corneal transplantation is performed. METHODS: A PUBMED-based literature search was carried out. RESULTS: Current knowledge on pathogenesis, clinical implications and treatment modalities for corneal neovascularization is discussed. CONCLUSIONS: Novel anti-angiogenic and antilymphangiogenic therapeutic strategies should reduce blindness associated with corneal neovascularization and subsequent graft rejection.

Angiogenesis Inhibitors↗

PubMed2003

[Classification of ocular surface disease. Part 1].

The ocular surface consists of the lid margin, conjunctiva and cornea which together with the tear system represent a functional entity. The diagnosis of ocular surface disease can be very difficult due to the similarity of various disease entities. The classification should be made on the pathological and pathophysiological characteristics of ocular surface disease. The first part of the classification comprises diseases of the lid margin, the tear system as well as diseases of the conjunctiva. Both the clinical presentation as well as the underlying pathophysiological and pathological characteristics of the most important ocular surface diseases are reviewed.

Conjunctival Diseases↗

PubMed2003

Corneal calcification after amniotic membrane transplantation.

BACKGROUND: /aims: Amniotic membrane transplantation (AMT) has become well established as a treatment for chronic epithelial defects, conjunctival reconstruction, and partial limbal cell deficiency. The aim of this study was to describe cases of corneal calcification following AMT and to search for risk factors that might predispose to this unusual finding. METHODS: Details of 117 AMTs on 93 corneas of 91 patients with a follow up period of at least 1 month performed since 1999 were collected prospectively. In those with calcification clinical photographs were studied and the medical records retrospectively examined. RESULTS: 15 calcifications in 117 AMTs (12.8%) were identified, occurring 3-17 (median 6.1) weeks after AMT, during a follow up period of 4-151 (median 25) weeks. Overall epithelial healing rate was 83%. Calcification covered a surface area between 0.7-40.5 mm(2) maximum size with varied morphology. The primary diagnosis was diverse. Risk factors included the use of phosphate eye drops and pre-existing calcification in the operative or other eye. No patient with a "patch" AMT developed calcification. CONCLUSIONS: Corneal calcification occurs after some cases of AMT. A common risk factor was the postoperative use of phosphate containing eye drops.

Adolescent↗

PubMed2002

Helicity amplitudes A1/2 and A3/2 for the D13(1520) resonance obtained from the gamma-->p-->-->ppi(0) Reaction.

The helicity dependence of the gamma-->p-->-->ppi(0) reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.

Journal Article↗

PubMed2002

Neutron polarizabilities investigated by quasifree Compton scattering from the deuteron.

Measuring Compton scattered photons and recoil neutrons in coincidence, quasifree Compton scattering by the neutron has been investigated at MAMI (Mainz) at theta(lab)(gamma) = 136 degrees in an energy range from 200 to 400 MeV. From the data a polarizability difference of alpha(n)-beta(n) = 9.8+/-3.6(stat)+2.1-1.1(syst)+/-2.2(model) in units of 10(-4) fm(3) has been determined. In combination with the polarizability sum alpha(n)+beta(n) = 15.2+/-0.5 deduced from photoabsorption data, the first precise results for the neutron electric and magnetic polarizabilities, alpha(n) = 12.5+/-1.8(stat)+1.1-0.6(syst)+/-1.1(model) and beta(n) = 2.7-/+1.8(stat)+0.6-1.1(syst)-/+1.1(model), are obtained.

Journal Article↗

PubMed2002

[Phototherapeutic keratectomy for recurrent corneal erosion syndrome (e-PTK). Report on 116 consecutive interventions].

BACKGROUND AND AIMS: Patients with recurrent corneal erosion syndrome can suffer both psychologically and socially due to excessive pain. After the failure of conservative treatment, conventional surgical interventions, such as anterior stromal puncture have been suggested. The purpose of this study was to assess the morphological and functional results of minimally invasive excimer laser phototherapeutic keratectomy (e-PTK) for treatment of recurrent corneal erosion syndrome and in particular, to evaluate the cumulative recurrence rate. PATIENTS AND METHODS: Between July 1990 and January 2001, 116 e-PTKs have been performed mostly in the acute stage of the disease in this single center study. In 15 eyes an unsuccessful PTK had previously been performed elsewhere. Reasons for the erosion included trauma ( n=80), Cogan's epithelial dystrophy ( n=14), bullous keratopathy ( n=2), and in 20 cases no cause could be detected. A manually guided spot profile was applied in 99 cases (pulse energy 10 mJ, repetition rate 2/s or 3/s, 66-330 pulses). In 17 cases a scanning slit procedure was applied (intended ablation per scan 1 microm, repetition rate 20/s, 447-1,017 pulses). The broad deepithelialisation of Bowman's layer was treated with defocussed overlapping laser pulses. RESULTS: Complete epithelial closure was achieved after an average of 2.3+/-1.3 (median 2) days, the mean follow-up was 2.2+/-1.6 years with a maximum of 5.6 years. Best corrected visual acuity increased from 0.6+/-0.4 preoperatively to 0.9+/-0.3 postoperatively. The keratometric central power remained constant (preoperative 43.0+/-2.2 D (diopters), postoperative 43.3+/-1.9 D). The median keratometric astigmatism remained constant at 1.0 D. Only in 2 patients was an iatrogenic, not completely reversible irregular astigmatism of more than 2 D induced during the learning curve. The spherical equivalent did not change significantly (-1.0+/-3.3 D preop., -1.1+/-3.4 D postop.). In 9 eyes (7.8%) a recurrent epithelial defect occurred after 2-24 (average 8+/-6) months. The cumulative 1-year recurrence rate was 6.5%, the 2-year recurrence rate was 11.5%, the 3-, 4-, and 5-year recurrence rates were all 13.6%. CONCLUSIONS: For recurrent corneal erosion syndrome, e-PTK performed with low pulse energy and low number of pulses can be considered an effective treatment modality to achieve a fast and mostly durable epithelial closure. Even after broad removal of the loose epithelium, change of refraction or induction of an irregular astigmatism with visual loss seems to be the exception.

Adult↗

PubMed2002

[Two years experience with the new accommodative 1 CU intraocular lens].

After marked improvement of optical rehabilitation of cataract patients during the last decades due to small incision surgery and foldable intraocular lenses (IOL), presbyopia is now one of the great unsolved questions in ophthalmology. During recent years a new accommodative IOL, the 1CU lens, has been developed based on the concepts of K.D. Hanna and on finite element computer simulation models. The 1CU IOL is designed to transform contracting forces of the ciliary muscle into anterior movement of the IOL optic (optic-shift concept). After the first implantation of a 1CU IOL in Erlangen in June 2000, we have now successfully implanted the 1CU IOL in over 90 patients. Our experiences and the results of several clinical studies indicate good and safe implantability, good centration, no IOL-specific complications, and good distance visual acuity. In comparison to control groups with conventional IOL, patients with the 1CU enjoyed significantly better distance-corrected near visual acuity, a larger accommodative range, and increased anterior and posterior axial movement of the lens optic after medical stimulation or inhibition of the ciliary muscle. We interpret our results as confirmation of the optic-shift concept of the 1CU IOL. Overall, the concept of accommodative IOL appears attractive and may have a great potential in the future. Additional studies including randomized blind multicenter evaluation of the 1CU IOL are necessary to further evaluate long-term and accommodative results.

Accommodation, Ocular↗

PubMed2002

[Development of a laser-optical tomograph for demonstration of CT imaging without ionizing radiation].

Computed X-ray tomography (CT) is one of the most powerful diagnostic procedures in medicine. In this study, we developed a laser-optical CT scanner for the use by students as part of their curriculum in biomedical engineering. Our CT set-up employs a linear-scan technique where the measurement objects (light absorbing phantoms embedded in immersion oil), the light emitter (modulated laserdiode), and the detector (photodiode) are moved by linear-step motors. The spatial resolution is limited by the width of the laser beam (2 mm) and the smallest achievable raster step size (0.02 mm). Optical tomographic images of various objects can be measured within a few minutes and allow the demonstration of imaging principles like extinction, scanning, projection, and reconstruction techniques.

Equipment Design↗

PubMed2001

[Morphological results after eccentric perforating keratoplasty].

OBJECTIVE: Due to unfavourable optical and immunological conditions, an eccentric position of the corneal transplant is limited to curative or tectonic indications. The purpose of this study was to assess the morphological results of eccentric homologous penetrating keratoplasty (PK) with respect to diagnosis as well as position and size of the corneal graft. PATIENTS AND METHODS: In our retrospective study, 122 cases of eccentric homologous PK in 96 eyes between 01/1989 and 10/1997 were included, which in 104 patients was necessary because of a corneal ulcer (36 previous PK, 21 areactive/rheumatic, 20 herpetic, 15 bacterial, 12 other). Elective PK was performed on 6 eyes with corneal scars, 7 eyes with ectatic corneal diseases (ECT) and 5 others. Using postoperative slides the following parameters were quantified: the graft diameter (GD) and transparency, the distance of the geometric centre of the cornea from the central trephination margin (ABS) as well as from the geometric centre of the graft (decentration, DEZ). Of these, 17 grafts were classified as eccentric peripheral keratoplasty (EPK) with the optical axis through the host cornea and 67 as eccentric central keratoplasty (ECK) with the optical axis through the graft. RESULTS: The average follow-up period was 25 months. In EPK (ulcers only, 5.0 +/- 1.7 mm) the mean GD was significantly lower than in ECK (78% ulcers, 7.0 +/- 1.3 mm) (p < 0.001). The decentration of EPK (3.5 +/- 1.1 mm) was significantly higher than for ECK (1.4 +/- 0.8 mm, p < 0.001). ABS of EPK was +1.3 +/- 0.9 mm and for ECK was -2.0 +/- 1.0 mm. Of the grafts in EPK and ECK 46%/57%, respectively were crystal clear, 18%/15% respectively showed minor decompensation and 36%/28% were completely cloudy. In cases of ulcers/scars/ECT/others, 45%/75%/100%/75% were crystal clear, respectively, 18%/25%/0%/0% showed minor decompensation and 37%/0%/0%/25% were completely cloudy. With increasing stages of cloudiness, the mean graft decentration increased from 1.4 +/- 1.1 mm (crystal clear) to 1.7 +/- 1.2 mm (minor decompensation) and 2.2 +/- 1.4 mm (completely cloudy). Transplants with greater GD (p = 0.04) and ABS (p = 0.01) were significantly more often clear. Ulcers were significantly more cloudy than scars/ECT (p < 0.01). The position of the graft and its cloudiness was not significantly correlated. CONCLUSION: The diagnosis leading to eccentric PK seems to have the greatest impact on long-term graft transparency. Our results indicate that an increasing decentration of the graft is not inevitably associated with an increasing probability of clouding. A central penetrating repeat keratoplasty may be considered in the non-inflamed interval after eccentric tectonic mini-keratoplasty.

Adolescent↗

PubMed2001

[Modeling corneal topography with a subdivision scheme in keratoconus].

BACKGROUND: Videokeratoscopy is often unable to obtain complete data sets in cases of irregular or asymmetric corneal topography. Subdivision schemes are very common in computer graphics for completion and smoothing of surfaces. Based on a network of triangular facets a smooth and complete surface in a standard coordinate system can be derived from topographic raw data. PATIENTS AND METHODS: We examined 88 patients with keratoconus and 40 normal controls. Polygons and polyhedra were defined from videokeratoscopic height data, and a surface was modeled using a modified butterfly subdivision scheme for a nonuniform sampled grid. To assess the model quality topographic raw data were changed to missing values centrally (at the apex of the cone) and in four midperipheral quadrants. The target value was the root mean square error, comparing the remodeled value of the subdivision scheme to the raw data at the position of the missing values for each group. RESULTS: Due to the nonuniform mesh of our Placido-based topographer we used a dynamic adaptive model and the governing dynamic differential equation. With a single missing value, no difference was detected between normals and patients with keratoconus. For a missing area consisting of 13 raw data points, the remodeling error was significantly higher in patients with keratoconus than in normals. With the neighborhood of 13 missing data points, the apex of the cone was remodeled in both groups of patients with less precision than with the peripheral missing data. CONCLUSION: The locality of the equation systems to be solved and the easy calculation of explicit formulas for the normals may simplify ray-tracing techniques and make subdivision attractive for large datasets in corneal topography even with irregular patterns.

Adult↗

PubMed2001

Graft endothelium and thickness after penetrating keratoplasty, comparing mechanical and excimer laser trephination: a prospective randomised study.

PURPOSE: To assess the impact of nonmechanical trephination on the graft endothelium and thickness after penetrating keratoplasty (PK). METHODS: Inclusion criteria for this prospective, randomised, cross-sectional, clinical study were: (1) Treatment between October 1992 and December 1997; (2) one surgeon (G.O.H.N.); (3) primary central PK; (4) Fuchs' dystrophy (diameter 7.5/7.6 mm) or keratoconus (diameter 8.0/8.1 mm); (5) graft oversize 0.1 mm; (6) no previous intraocular surgery; (7) 16-bite double-running diagonal suture. In 179 patients (mean age 51+/-18 years), PK was performed using either the 193-nm Meditec MEL60 excimer laser ("Excimer") along metal masks with eight "orientation teeth/notches" (53 keratoconus, 35 Fuchs' dystrophy) or motor trephination with the Mikrokeratron (Geuder) ("Control": 53 keratoconus, 38 Fuchs' dystrophy). For donor trephination from the epithelial side an artificial anterior chamber was used in both groups. In 27% of the excimer and 29% of the control group a triple procedure was performed. Specular microscopy (EM-1000, Tomey) and pachymetry (SP-2000, Tomey) were performed before removal of the first suture (0.4+/-0.2 years postoperatively), before (1.1+/-0.4 years) and after (1.7+/-0.6 years) removal of the second suture but before any additional surgical intervention. RESULTS: Endothelial cell count: Neither "two-sutures-in" (1953+/-426/1804+/-385 cells/mm2, p=0.13), "one-suture-in" (1629+/-439/1765+/-440 cells/mm2, p=0.27), nor "all-sutures-out" (1259+/-493/1294+/-532 cells/mm2, p=0.83) differed significantly between Excimer and Control. Graft thickness: Neither "two-sutures-in" (527+/-58/524+/-16 mucrom, p=0.89), "one-suture-in" (537+/-72/551+/-40 microm, p=0.86), nor "all-sutures-out" (576+/-53/565+/-62 microm, p=0.38) differed significantly between Excimer and Control. Cell count and corneal thickness were not significantly different comparing Fuchs' dystrophy and keratoconus or comparing PK only and triple procedures. Graft thickness and endothelial cell count correlated highly significantly inversely with "all sutures out" (P<0.0001). CONCLUSIONS: Excimer laser trephination from the epithelial side using an artificial anterior chamber in donors seems to have no disadvantages concerning the graft endothelium after PK. Endothelial cell loss was not increased in eyes with Fuchs' dystrophy compared with keratoconus or after triple procedures compared with PK only.

Adolescent↗

PubMed2001

Blood-aqueous barrier breakdown after penetrating keratoplasty with simultaneous extracapsular cataract extraction and posterior chamber lens implantation.

BACKGROUND: The purpose of this study was to quantify breakdown of the blood-aqueous barrier (BAB) following penetrating keratoplasty (PK) with simultaneous extracapsular cataract extraction and posterior chamber lens implantation (triple procedure) and compare it with the alterations following PK only. METHODS: This study included 72 eyes after triple procedure and 227 eyes after PK only. The diagnosis for PK was Fuchs dystrophy in 39%, keratokonus in 44%, stromal corneal dystrophy in 3% and avascular corneal scars in 6% of cases. The postoperative topical steroid treatment was standardized in both groups. Aqueous flare was quantified using the laser flare-cell meter (FC-1000, Kowa) at defined postoperative intervals (10 days, 6 weeks, then every 3 months until 1 year postoperatively). Patients with conditions associated with impairment of the BAB were excluded from the study. RESULTS: In the early postoperative course, aqueous flare values (photon counts/ms) were significantly higher in patients with triple procedure (21.9 +/- 11.0) than in patients with PK only (9.8 +/- 3.2; P = 0.001). At 6 weeks postoperatively, aqueous flare returned to normal levels in patients after PK only (5.2 +/- 2.3), whereas patients with triple procedure still showed significantly increased flare values (10.8 +/- 5.6; P = 0.01). At 6 months postoperatively, aqueous flare values of patients with triple had returned to normal levels (6.8 +/- 3.8) and did not differ significantly from those after PK only (5.2 +/- 1.9; P = 0.09). CONCLUSION: Our results indicate that triple procedure causes a more extensive and longer-lasting breakdown of the blood-aqueous barrier than PK only. Quantification of aqueous flare with the laser flare-cell meter is useful in the postoperative follow-up after triple procedure. Further studies are required to investigate the clinical relevance of BAB breakdown on endothelial cell count and the incidence of subsequent immunological graft rejection.

Aqueous Humor↗

PubMed2001

Impact of short-term versus long-term topical steroids on corneal neovascularization after non-high-risk keratoplasty.

PURPOSE: To analyze incidence and extent of corneal neovascularization (CN) after non-high-risk keratoplasty and to find out whether duration of postoperative topical steroid therapy (6 vs 12 months) affects CN, corneal endothelial cell count, pachymetry, aqueous flare values, and best-corrected visual acuity at 1 year after keratoplasty. METHODS: Patients of the prospective Erlangen non-high-risk keratoplasty study with available high-quality corneal photographs taken preoperatively and 1 year later were analyzed (n=136). Corneal photographs were evaluated by two independent observers in a standardized semiquantitative fashion. Slides were projected with 100x magnification and corneal vessels classified into five grades with regard to the limbus, sutures and host-graft junction in each of 12 corneal sectors. Incidence and extent of CN after keratoplasty and relation to short-term (0-6 months) versus long-term (0-12 months) postoperative topical steroid therapy were analyzed. The effect of duration of topical steroid therapy on corneal endothelial cell count, pachymetry, aqueous flare values, and best corrected visual acuity was also analyzed. Of the 136 patients, 69 (51%) were randomly assigned to short-term and 67 to long-term topical prednisolone acetate 1%. RESULTS: Fifty-eight percent of patients (n=79) developed a CN within 1 year after keratoplasty in at least one corneal sector (mean 3.1 +/- 2.2, range 1-10). At 1 year after keratoplasty, only in 12% of these patients did at least one vessel reach the host-graft junction or grow into the donor cornea, whereas in 51% vessels were seen beyond the outer suture ends of the double running suture without reaching the host-graft junction. In 37%, capillaries were located between limbus and outer suture ends. New vessels usually pointed directly or indirectly to the outer suture ends and usually were located around the 12 o'clock and 6 o'clock positions. There was no significant difference regarding incidence and extent of CN 1 year after keratoplasty between the long-term and the short-term group. Duration of topical steroid therapy had no significant effect on corneal endothelial cell count and thickness, aqueous flare values and best-corrected visual acuity at 6 and 12 months postoperatively (only at 12 months, corneas in the long-term treatment group were slightly thicker; P=0.03). Interobserver correlation of vessel assessment was 0.77 (Kendall's tau B). CONCLUSIONS: CN is a common phenomenon after non-high-risk keratoplasty. New vessels rarely reach the host-graft junction, most commonly develop from the 6 o'clock and 12 o'clock positions and are usually located between epithelium and Bowman's layer (i.e., at the level of the superficial suture). The direction of vessel growth from the limbus towards the outer suture ends suggests release of angiogenic factors in this area. Prolongation of topical steroid therapy after non-high-risk keratoplasty beyond 6 months in this study did not significantly influence incidence and extent of CN, corneal endothelial cell count, aqueous flare values and best-corrected visual acuity observed 1 year after keratoplasty.

Administration, Topical↗

PubMed2001

Corneal thickness measurements with contact and noncontact specular microscopic and ultrasonic pachymetry.

PURPOSE: To evaluate the central corneal thickness values in normal and postkeratoplasty corneas with the new Topcon SP-2000P noncontact specular microscopic, contact specular microscopic, and the "common standard" ultrasonic pachymetry. METHODS: Central corneal thickness was determined in 119 eyes of 81 patients (73 normal eyes of 44 patients and 46 eyes after penetrating keratoplasty) first with a noncontact specular microscopic (Topcon SP-2000P; Topcon Corporation, Tokyo, Japan), then an ultrasonic (AL-1000; Tomey, Erlangen, Germany), and finally with a contact specular microscopic (EM-1000; Tomey, Erlangen, Germany) pachymetry two times each by the same investigator. RESULTS: Reliability of the central corneal measurements was equally high both in normal and in postkeratoplasty corneas with all of the instruments (Cronbach alpha = 0.99). Noncontact specular microscopic corneal thickness determination correlated significantly both with ultrasonic (r =.86, P <.0001) and contact specular microscopic pachymetry (r =.62, P <.0001). The ultrasonic pachymetry correlated well with the Tomey pachymetry (r =.69, P <.0001). The Topcon normal mean central corneal thickness value (542 +/- 46 microm) was 28 +/- 4 microm lower (P <.0001) compared with the ultrasonic data (570 +/- 42 microm), which was 68 +/- 1 microm lower (P <.0001) compared with Tomey thickness (638 +/- 43 microm). CONCLUSIONS: Central corneal thickness measurements with noncontact specular microscopic, contact specular microscopic, and ultrasonic pachymetry demonstrate that each of the instruments is reliable but cannot be simply used interchangeably.

Aged↗