PubMed Health⌕ Search

Biomedical subjects

B Seitz

Publications and source records attributed to B Seitz.

At least 91 records · Page 5Linked to original sources
PubMed1999

[Expulsive hemorrhage in perforating keratoplasty--incidence and risk factors].

BACKGROUND: Expulsive hemorrhage is a severe complication of intraocular surgery. In a retrospective study we looked up surgical records of all penetrating keratoplasties (PK) performed in our department between 1989 and 1998. In all patients suffering from expulsive or preexpulsive choroidal hemorrhage we intended to find out possible risk factors and to report on the final outcome of these eyes. PATIENTS AND METHODS: Between January 1989 and November 1998 a total of 2421 PKs were performed. Nine preexpulsive and three expulsive hemorrhages occurred. The group of patients with preexpulsive hemorrhage consists of four females and five males (mean age 57 +/- 6.5 years). Three patients (one female, 2 males; mean age 67 +/- 8.5 years) suffered from expulsive hemorrhage. RESULTS: Incidence of expulsive hemorrhage was 0.1% (preexpulsive hemorrhage 0.4%). All twelve operations were performed under general anesthesia. Risk factors for preexpulsive hemorrhage were: previous ocular surgery (three patients), ocular trauma (2 patients) and internal diseases (five patients): arterial hypertension, coronary heart disease, diabetes. Preoperative visual acuity was light perception to 4/20, visual acuity at the last postoperative examination after a mean follow-up of 41.0 +/- 22.6 months ranged from light perception to 12/20. Risk-factors for expulsive hemorrhage were: previous ocular surgery (two patients), primary open angle glaucoma (two patients), coronary heart disease (one patient) und asthma bronchiale (one patient). One of the patients awoke from general anesthesia during the "open-sky" situation. Preoperative visual acuity was light perception to 2/400, visual acuity at the last postoperative examination (mean follow-up 14.0 +/- 1.0 months) was light perception in all eyes. CONCLUSION: The incidence of an expulsive hemorrhage was 0.1% in 2412 Pks. Risk factors are ocular and internal predispositions which can hardly be controlled, although arterial blood pressure was not significantly elevated during opening of the globe.

Adult↗
PubMed1999

[Calculating the localization and dimension of the real pupil in keratoconus with ray tracing of corneal topography data].

BACKGROUND: It is crucial to center surgical procedures for optical indications on the pupil or the optical axis of the eye. In keratoconus the pupil appears to be dislocated due to optical aberrations of corneal topography. The purpose of this study was to evaluate the real pupil structure from the virtual image using exact raytracing techniques. PATIENTS AND METHODS: Eighty-eight patients with keratoconus (46 with mild and 42 with severe clinical signs) and a control group of 40 normal subjects were included in this study. Topographic height data were calculated from refraction data of a commercially available topographer (TMS-1) using a local approximation algorithm and a convex surface was modelled using a subdivision scheme. For the posterior corneal surface we postulated an aspherical surface with a central radius of curvature of 6.5 mm using Navarro's model eye. At the virtual pupil outline a bundle of parallel rays were intersected with the anterior and posterior corneal surface and refracted into the anterior chamber. The intersections of these rays with the pupil plane was defined as the real pupil outline. We assessed the amount and direction of pupil dislocation, the ratio between the virtual and real pupil size for each group and correlated these parameters with the central corneal power. RESULTS: The size of the virtual pupil exceeded the reference value of the real pupil in the normal group by 11%, in the group with mild keratoconus by 19% and in the group with severe keratoconus by 35%. The center of the virtual pupil was decentered 0.06 mm in the normal group, 0.49 in the group with mild keratoconus and 1.24 mm in the group with severe keratoconus. Whereas the direction of decentration was randomly in the normal group, we measured a preferred decentration to the inferior quadrants in mild keratoconus and a systematic decentration to the temporal inferior quadrant in severe keratoconus. Correlation of the optical dislocation did not correlate with central corneal power in any group. CONCLUSIONS: In keratoconic eyes the pupil outline is distorted and dislocated due to optical aberrations of the cornea. Exact raytracing technique allows the calculation of the real pupil outline from the virtual image and the topographic height of both corneal surfaces. Knowledge about the real pupil position may have an impact on adequate centration of keratorefractive surgery and penetrating keratoplasty.

Adult↗
PubMed1999

[Transplant endothelium and measuring corneal thickness after non-high-risk keratoplasty with briefly or long-term preserved corneal donor tissue].

PURPOSE: The corneal endothelial cell density is essential for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density after non-high-risk PK and to check for possible correlations with storage parameters of the donor corneas using two different storage methods. PATIENTS AND METHODS: Endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) and central corneal thickness (ultrasonic pachymetry SP-2000, TOMEY, Erlangen) were assessed 6 weeks, 3, 6, 9 months and one year postoperatively in 168 non-high-risk PKs. Short-term-preserved donor corneas were used in 89 patients, whereas in 79 patients organ-cultured corneas were used. The donor trephination was performed from the epithelial side using an artificial anterior chamber. The postoperative treatment with topical steroids was standardized. The mean donor post-mortem time was 9.6 +/- 8.0 hours for short-term-preserved and 17.6 +/- 10.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 71 +/- 49 and 380 +/- 167 hours (p < 0.0001), respectively. RESULTS: Endothelial cell density did not differ significantly between the two storage methods (p > 0.05). At 6 weeks postoperatively, the mean endothelial cell density was 2042 +/- 675 cells/mm2 for short-term-preserved corneas and 1972 +/- 522 cells/mm2 for organ-cultured corneas (p = 0.7). Endothelial cell density did not decrease significantly (p > 0.05) within the observation period of 12 months in both groups (after 12 months: 1868 +/- 957 cells/mm2 and 1638 +/- 643 cells/mm2, respectively). The mean corneal thickness was 542 +/- 50 microns for short-term-preserved and 541 +/- 55 microns for organ-cultured corneas and remainded unchanged during the follow-up of 12 months (542 +/- 42 microns and 521 +/- 43 microns, respectively). Neither the group of short-term-preserved corneas nor organ-cultured corneas showed a significant correlation between endothelial cell density or central cornea thickness with post-mortem time or with storage time of the donor corneas at any postoperative stage (p > 0.1). CONCLUSION: During the first year after PK, only a small decrease in endothelial cell density was observed in comparison with the 6-weeks finding. The storage method does not seem to affect the short-term changes of endothelial cell density. Further long-term studies are necessary to assess the clinical relevance of these observations.

Adult↗
PubMed1999

[Development of visual acuity in the early phase after photorefractive keratectomy in myopia].

BACKGROUND: Photorefractive keratectomy (PRK) using the excimer laser is an accepted surgical technique for correction of myopic refraction errors in case of spectacle or contact lens incompatibility. The purpose of this study was to assess the development of uncorrected (UVA) and best-corrected visual acuity (CVA) in the early course following PRK. PATIENTS AND METHODS: 48 eyes of 29 patients that underwent myopic photorefractive keratectomy using 193 nm excimer laser (MEL 60, Aesculap-Meditec) were included in this study. The mean preoperative spherical equivalent was -5.3 +/- 2.4 diopters (D) (range -1.75 to -9.5 D). Pre-, intra- and postoperative treatment was standardized. The median time interval to complete epithelial closure was 2 days. According to their spherical equivalent, patients were divided in two groups: group 1 with myopia < or = 6 D (n = 28), group 2 with myopia more than 6 D (n = 20). Examination of UVA and CVA were performed preoperatively and on days 3, 7 as well as 1 month, 3 and 6 months postoperatively. RESULTS: On day 3 after surgery UVA was 0.43 +/- 0.21 for group 1 with myopia < or = 6 D, and 0.36 +/- 0.14 for group 2 with myopia more than 6 D. The UVA was stable after 3 months (0.92 +/- 0.29 and 0.66 +/- 0.20, respectively), the CVA was stable after 1 month (1.04 +/- 0.18 and 0.86 +/- 0.19, respectively). After surgery, the UVA increased by +0.73 +/- 0.25, whereas the CVA increased by +0.05 +/- 0.10 for the whole group. The difference comparing pre- and postoperative UVA was significantly higher in group 1 (0.81 +/- 0.22) than in group 2 (0.60 +/- 0.26) (p = 0.002). However, postoperative CVA values were not significantly different from preoperative values in both groups after 6 months (p = 0.3). CONCLUSION: Useful uncorrected visual acuity is normally achieved at day 3 after PRK in eyes with mild to moderate myopia. With higher degrees of myopia the uncorrected visual acuity does increase slower towards a lower level. One of the reasons for this phenomenon might be a significant regression of the refractive effects during the first half year after surgery.

Adult↗
PubMed1999

[Clearing of the host cornea after penetrating keratoplasty for pseudophakic bullous keratopathy].

BACKGROUND: In this study, we have focussed on the clearing of the host cornea after successful penetrating keratoplasty (PK) for pseudophakic bullous keratopathy and the clinical factors that may influence this phenomenon. PATIENTS AND METHODS: We recruited the study group out of all keratoplasties performed in our department between 1984 and 1996 using the following criteria: (1) pseudophakic bullous keratopathy that involved the whole host cornea preoperatively, (2) no additional ocular diseases, (3) all operations performed before January 1st 1996, (4) sufficient photodocumentation, (5) complete clinical records, (6) clear graft at the end of the follow-up period. Using these criteria, 48 patients (28 females and 20 males; mean age at the time of surgery 72.7 +/- 8.8 years) were included in the study group. Donor age ranged from 34 to 86 years (mean age 65.8 +/- 12.0 years). The opacity of the host cornea was graded from 0 to 3 (0 = clear cornea; 3 = total opacity) within a circular zone of 1 mm diameter adjacent to the graft in four quadrants (I-IV). Finally, an index for the mean opacity index was calculated [TG = (I + II + III + IV)/4] and correlated with clinical parameters. RESULTS: The index for the mean opacity was 2.8 preoperatively. After a mean follow-up of 9.6 +/- 12.3 months, the index decreased significantly to 1.8 (p = 0.01). Mean visual acuity before PK was 20/400, at the end of the follow-up it was 20/50. The index of opacification was significantly correlated with patients age (p = 0.03; r = 0.2) and inversely with the follow-up period (p = 0.001; r = -0.6) and with the visual acuity at the end of the follow-up period (p = 0.05; r = -0.2). Using the 193-nm excimer laser for donor and host trephination led to a higher clearing of the host circular zone (mean opacification index 1.7) than mechanical trephination (mean 2.1) (p = 0.01). CONCLUSION: Our results indicate that expansion of donor endothelial cells onto host's Descemet's membrane is possible and successful with respect to clearing of the host cornea in pseudophakic bullous keratopathy. Nonmechanical excimer laser trephination of donor and host from the epithelial side seems to promote this phenomenon due to a better apposition of the cut surfaces.

Aged↗
PubMed1999

[Keratoconus screening with wave-front parameters based on topography height data].

BACKGROUND: The image-forming properties of a keratoconus eye are degraded even in the early stage of this disease. The purpose of this study was to develop keratoconus detection scheme based on topography height data independent of the currently used system which avoids the disadvantages of detection algorithms currently used in clinical practice. PATIENTS AND METHODS: Eighty-eight patients with keratoconus (46 with mild and 42 with severe clinical signs) and a control group of 40 normal subjects were included in this study. A decomposition of corneal topography height data into orthogonal Zernike polynomials was performed using the commercially available corneal topographer TMS-1. Expansion coefficients of the different groups were compared to evaluate significant differences. Elevated terms were used to detect the disease. The statistical significance of this detection scheme was compared to those given by the keratoconus detection software of the TMS-1. From the elevated Zernike terms a neural network was constructed and optimized for dividing keratoconus patients and normal controls. RESULTS: Some low-order Zernike coefficients with a radial order n < 8 were found to be elevated in patients with keratoconus and were used to define a new detection algorithm. This index performed at least as well (sensitivity in mild/severe keratoconus 93.4%/100% with a specificity of 100%) as keratoconus detection schemes based on the Klyce-Maeda and the Rabinowitz-Klyce indices as well as the I-S value and the Surface Asymmetry Index SAI in our study population. CONCLUSIONS: Zernike decomposition of corneal topography height data allows a definition of an exact and robust algorithm for detection of keratoconus. It avoids the drawbacks of refractive power based definitions and is independent on the individual topographer design.

Adolescent↗
PubMed1999

[Topography-based calculation of keratoconus dimensions].

BACKGROUND: Keratoconus is a corneal dystrophy which usually develops in the second or third decade of life and shows various speed of progression. This disease may degrade the image-forming properties of the eye even in its early stage. The purpose of this study was to support the conventional clinical qualitative diagnostic methods of keratoconus handling with a topography-based algorithm to quantify the "ballooning" of the anterior corneal surface. PATIENTS AND METHODS: Eighty-eight patients with keratoconus (46 with mild and 42 with severe clinical signs) and a control group of 40 normal subjects were included in this study. Topographic height data were calculated from refraction data of a commercially available topographer (TMS-1) using a local approximation algorithm. A decomposition of corneal topography height data into orthogonal Zernike polynomials was performed to define a asphero-cylindrical model surface. From the difference of the raw height data and the model surface, the base, height and volume as well as the localization of the protrusion was quantified. RESULTS: The height of the corneal protrusion (23 to 71 microns), the volume of the cone (0.066 to 0.141 mm3) and the horizontal dimension (0.67 to 1.32 mm) increased highly significantly. In contrast, comparing the early to the severe stage of the disease the vertical dimension of the cone (0.64 to 0.93) changed much less. In the severe stage, the center of the protrusion was much more decentred (1.33 mm) than in the early stage (0.44) due to a shift in the inferior direction. CONCLUSIONS: The quantification of cone dimensions using corneal topography height data has the potential to assist qualitative clinical graduation in keratoconus independent of the system currently used. The knowledge about the exact amount of corneal protrusion and position of the cone may improve the assessment of the progression of the disease, thus being helpful for indication of a penetrating keratoplasty.

Adult↗
PubMed1999

[Crystalline keratopathy as a presenting sign of multiple myeloma].

BACKGROUND: Noninfectious crystalline corneal degenerations can be classified from the clinical and genetical point of view into 3 groups: 1. primary hereditary (Schnyder), 2. secondary hereditary (cystinosis) and 3. secondary non-hereditary in association with disorders of serum protein or lipid composition. PATIENT: We report on a 63-year-old man with reduced vision and grey-white, crystalline, monomorpheous deposits in the corneal stroma. Further investigation revealed IgG myeloma. RESULTS: We performed a penetrating keratoplasty for visual improvement. On histopathological examination, typical eosinophilic, PAS-positive, interlamellar deposits staining brilliant red with Masson's trichrome were found diffusely scattered throughout the stroma. Electron microscopy showed intracellular, rhomboid-shaped deposits enveloped by a membrane. CONCLUSION: The appearance of a crystalline keratopathy should be followed by an internal examination for early detection and adequate treatment of a systemic disease.

Antineoplastic Agents, Hormonal↗
PubMed1999

Long-term ultrastructural changes in human corneas after tattooing with non-metallic substances.

AIM: To investigate the ultrastructural appearance and the deposition pattern of dye particles in long term non-metallic corneal tattooing. METHODS: Two tattooed human corneas were obtained by keratoplasty. One corneal button was fixed in Karnovsky's solution and the other in Trumps' solution. Both corneas were divided and processed for conventional light (LM) and transmission electron microscopy (TEM). Five additional formalin fixed corneas with tattoos were retrieved from paraffin for TEM. The time between tattoo and removal of the corneal button/enucleation ranged from 7 to 61 years. All seven corneas were examined using a Jeol JCXA733 microprobe for wave length dispersive analysis in order to exclude any presence of metallic salts in the tattooed area. RESULTS: Histologically, clumps of brown-blackish granules were present mainly in the mid stroma, but also in anterior and partially in the posterior half of the stroma. On TEM, numerous round and oval electron dense particles were seen in the cytoplasm of keratocytes arranged as clusters or large islands. The larger particles appeared black, while the smaller particles were grey. In well fixed tissue a unit membrane was observed around these clusters. No granules were detected in the extracellular matrix. CONCLUSIONS: Keratocytes can actively ingest and retain tattooing particles of non-metallic dyes within their cell membrane for very long periods of time.

Adolescent↗
PubMed1999

"Orientation teeth" in non-mechanical laser corneal trephination for penetrating keratoplasty: 2.94 microm Er:YAG v 193 nm ArF excimer laser.

BACKGROUND/AIMS: "Orientation teeth" at the donor trephination margin and correspondent "notches" at the host margin facilitate graft orientation and avoid "horizontal torsion" induced by asymmetric suture placement. In this study the quality and reproducibility of these structures created by non-mechanical laser corneal trephination were compared using two laser emissions. METHODS: The procedure was performed in 20 enucleated pigs' eyes using open metal masks with eight "orientation teeth/notches" (0.3 x 0.15 mm, base x height), an automated globe rotation device, and either a 193 nm ArF excimer laser or a Q switched 2.94 microm Er:YAG laser. "Teeth/notches" were analysed by planimetry and scanning electron microscopy (SEM). RESULTS: Mean size was 0.30 (0.027) x 0. 16 (0.017) mm for "teeth" and 0.30 (0.035) x 0.15 (0.021) mm for "notches" (excimer), and 0.31 (0.022) x 0.16 (0.015) mm and 0.30 (0.031) x 0.14 (0.021) mm respectively (Er:YAG). Overall, variability of notches was higher than that of teeth. By SEM, comparable cut regularity and sustained ablation profile were observed with both lasers. However, the corneal surface at the cut edge appeared slightly elevated (</=35 microm) in the Er:YAG group. CONCLUSION: Orientation teeth/notches resembling those obtained with the excimer laser can be created using the Q switched Er:YAG laser, with potential advantages of lower costs, convenient equipment size, and solid state safety.

Animals↗
PubMed1999

Zernike representation of corneal topography height data after nonmechanical penetrating keratoplasty.

PURPOSE: To demonstrate a mathematical method for decomposition of discrete corneal topography height data into a set of Zernike polynomials and to demonstrate the clinical applicability of these computations in the postkeratoplasty cornea. METHODS: Fifty consecutive patients with either Fuchs' dystrophy (n = 20) or keratoconus (n = 30) were seen at 3 months, 6 months, and 1 year (before suture removal) and again after suture removal following nonmechanical trephination with the excimer laser. Patients were assessed using regular keratometry, corneal topography (TMS-1, simulated keratometry [SimK]), subjective refraction, and best-corrected visual acuity (VA) at each interval. A set of Zernike coefficients with radial degree 8 was calculated to fit two model surfaces: a complete representation (TOTAL) and a representation with parabolic terms only to define an approximate spherocylindrical surface (PARABOLIC). The root mean square error (RMS) was calculated comparing the corneal raw height data with TOTAL (TOTALRMS) and PARABOLIC (PARABOLICRMS). The cylinder of subjective refraction was correlated with the keratometric readings, the SimK, and the respective Zernike parameter. Visual acuity was correlated with the tilt components of the Zernike expansion. RESULTS: The measured corneal surface could be approximated by the composed surface 1 with TOTALRMS < or = 1.93 microm and by surface 2 with PARABOLICRMS < or = 3.66 microm. Mean keratometric reading after suture removal was 2.8+/-0.6 D. At all follow-up examinations, the SimK yielded higher values, whereas the keratometric reading and the refractive cylinder yielded lower values than the respective Zernike parameter. The correlation of the Zernike representation and the refractive cylinder (P = 0.02 at 3 months, P = 0.05 at 6 months and at 1 year, and P = 0.01 after suture removal) was much better than the correlation of the SimK and refractive cylinder (P = 0.3 at 3 months, P = 0.4 at 6 months, P = 0.2 at 1 year, and P = 0.1 after suture removal). Visual acuity increased from 0.23+/-0.10 at the 3-month evaluation to 0.54+/-0.19 after suture removal. After suture removal, there was a statistically significant inverse correlation between VA and tilt (P = 0.02 in patients with keratoconus and P = 0.05 in those with Fuchs' dystrophy). CONCLUSIONS: Zernike representation of corneal topography height data renders a reconstruction of clinically relevant corneal topography parameters with a marked reduction of redundance and a small error. Correlation of amount/axis of refractive cylinder with respective Zernike parameters is more accurate than with keratometry or respective SimK values of corneal topography analysis.

Adolescent↗
PubMed1998

Stromal thermal effects induced by nonmechanical (2.94-mum) erbium:YAG laser corneal trephination.

OBJECTIVE: To determine stromal thermal changes after erbium (Er):YAG laser corneal trephination with the use of 2 open masks. METHODS: Corneal trephination was performed in 89 enucleated pig eyes with an Er:YAG laser (400-microsecond pulse duration), 4 open masks (2 metallic and 2 ceramic) for both donors and recipients, and an automated globe rotation device. Different combinations of laser settings were used: pulse energy, 100, 200, and 400 mJ; repetition rate, 2 and 5 Hz; and spot size, 1.3 and 3.2 mm. Thermal effects in corneal stroma and regularity of the cut edges were quantitatively assessed by light microscopy, transmission and scanning electron microscopy. RESULTS: Best regularity and minimal thermal effects of the cut were observed with the use of ceramic masks at 200 mJ, 2 Hz, and 3.2-mm spot size, with middepth thermal changes of 18 +/- 2 microm. Effects increased with cut depth and were lower in donor corneas and with the use of ceramic masks (P<.001). Regularity of the cut was higher in the donors (P = .05) with lower repetition rates (P<.001). CONCLUSIONS: Even with the "free-running" Er:YAG laser mode, features of the trephination cut resembling those created by the 193-nm excimer laser along metal mask were achieved. Ceramic masks may be more suitable than metal masks. The Er:YAG laser seems to have the potential to be a compact and low-cost alternative in nonmechanical trephination for penetrating keratoplasty. CLINICAL RELEVANCE: Thermal effects after corneal trephination with the free-running Er:YAG laser (2.94 mm) are limited and predictable.

Animals↗
PubMed1998

[Immunologic transplant reactions after non-mechanical corneal trepanation with the excimer laser].

BACKGROUND: Nonmechanical trephination has been established as the standard procedure in penetrating keratoplasty (PK) for avascular corneal diseases at our institution. The purpose of this study was to analyze the incidence and reversibility of immunologic graft reactions after nonmechanical trephination and to detect potentially causative factors. PATIENTS AND METHODS: Out of a total series of 400 nonmechanical PKs, 286 consecutive procedures with sufficient follow-up performed between 07/1989 and 09/1997 were included in the study (104 x keratoconus, 78 x Fuchs' dystrophies, 31 x bullous keratopathies, 28 x ulcers, 25 x avascular scars, 12 x stromal dystrophies, 4 x buphthalmos, 4 x others; 202 x PK only, 84 x combined procedures; 276 first PK). The age of the 138 females and 148 males at the time of surgery ranged from 16 to 89 (mean 55 +/- 19) years. The recipient and donor trephinations were performed from the epithelial side using an 193-mm excimer laser (MEL50 or MEL60, Aesculap-Meditec, 1.5 x 1.5 mm spot mode, 16-24 mJ/pulse, repetition rate 30 or 25/s; metal masks). The shape of the recipient trephination was either circular with four or eight "orientation teeth" (n = 251; 5.0-8.0 mm diameter) or elliptical (n = 35, 6.0 x 7.0 to 7.5 x 8.5 mm diameter). In 62% of procedures fresh or short-term-preserved donor tissue was used, and in 38% of procedures the donor tissue was organ-culture-preserved. RESULTS: During a mean follow-up of 22 +/- 18 months (maximum 7.7 years), 10 acute diffuse (3 irreversible; 1.0%) and 3 chronic focal endothelial graft reactions occurred (4.5%) not earlier than 4 months and not later than 35 months after PK. Elective procedures (3.5%) resulted in significantly (P = 0.01) less reactions than acute corneal ulcers (14.3%). After 1, 2 and 3 years, the cumulative reaction rates (Kaplan-Meier values) were 1.3%, 6.3% and 13.9% in elective procedures, none of which, however, occurred after 26 elliptical trephinations. With fresh or short-term-preserved donor tissue (4.2%), graft reactions did not happen more frequently but earlier (12 +/- 6 months) than with organ-culture-preserved donor tissue (2.2%, 30 +/- 6 months). In patients with keratoconus (4.9%), reactions occurred more frequently (P = 0.05, LogRank) and earlier than in patients with Fuchs' dystrophy (1.3%). CONCLUSIONS: In addition to well-established optical advantages, nonmechanical trephination seems to have no immunologic drawbacks.

Adolescent↗
PubMed1998

[Correlation between semi-quantitative classification of corneal topography and the coefficient of Fourier transformation after non-mechanical perforating keratoplasty].

BACKGROUND: Semiquantitative classification of corneal topography after penetrating keratoplasty has the potential for focusing information about the areal dioptric power of the cornea. The purpose of this study was to objectify the procedure of manual semiquantitative classification using a Fourier transform of corneal topography power data and to correlate both methods. PATIENTS AND METHODS: Fifty patients each (30 keratoconus, 20 Fuchs dystrophy) underwent nonmechanical trephination (excimer laser MEL60, Aesculap-Meditec, Jena) in penetrating keratoplasty. All procedures (7.5-mm trephination diameter in Fuchs, 8.0 mm in keratoconus, double-running 10-0 nylon suture) were done by one surgeon. Pre-, intra- and postoperative treatment were identical. At the follow-up examinations, the keratometric astigmatism, qualitative and quantitative criteria of the automatic videokeratography, visual acuity and refraction were assessed. Corneal topography was classified both manually and based on Fourier coefficients. RESULTS: After a mean follow-up of 24 +/- 5 months, keratometric net astigmatism was 3.0 and 2.7 D with keratoconus and Fuchs dystrophy. Corneal topography analysis showed a higher orthogonality of the bow-tie shape and less asymmetry between opposite hemimeridians with increasing follow-up after keratoplasty. The semiquantitative classification showed a statistically significant correlation with the classification based on Fourier coefficients, especially with higher astigmatism and after suture removal (P = 0.04/0.01 before/after suture removal). DISCUSSION: After nonmechanical trephination, the semiquantitative classification of corneal topography can be synthetized using Fourier analysis of corneal dioptric power data. In the future, this method may be favored for prediction of potential best-corrected visual acuity after penetrating keratoplasty.

Adult↗
PubMed1998

Retroviral vector-mediated gene transfer into keratocytes: in vitro effects of polybrene and protamine sulfate.

BACKGROUND: To determine the potential of somatic gene transfer as a novel technique for modulating corneal wound healing on a cellular level, the successful transduction of human keratocytes should be ascertained in vitro. In addition, the ability of different polycations to increase the transduction efficiency and their antiproliferative and cytotoxic effects should be assessed. METHODS: To test transduction efficiency (X-Gal staining), cultured human keratocytes were incubated for 2 h with a retroviral vector bearing the beta-galactosidase gene, with and without the addition of polybrene or protamine sulfate. To test the antiproliferative and cytotoxic effects, cultured human keratocytes were incubated with various concentrations of polybrene and protamine sulfate (0.08 to 800 micrograms/ml) for 2, 24 and 72 h, and evaluations were performed by means of an XTT-based colorimetric assay and phase-contrast microscopy. RESULTS: Human keratocytes in vitro were transduced successfully with the beta-galactosidase gene (3.5 +/- 1.0%). Transduction efficiency was significantly (P < or = 0.01) improved by addition of a polycation (from 12.3 +/- 1.7% to 18.6 +/- 2.3%), but there was no significant difference between the effects of polybrene and those of protamine sulfate. Both drugs induced a highly significant dose-dependent inhibition of proliferation (P < 0.001). ID50 ranged from 11 to 22 micrograms/ml with polybrene and from 15 to 244 micrograms/ml with protamine sulfate. Only with doses of 80 and 800 micrograms/ml did protamine sulfate produce less antiproliferative effects than polybrene (P < or = 0.04). The lowest concentrations induced no morphological signs of cytotoxicity, whereas these signs were mild at 8 micrograms/ml and moderate to severe at the highest concentrations. CONCLUSIONS: Both polybrene and protamine sulfate can significantly improve the in vitro efficiency of successful retroviral vector-mediated gene transfer into keratocytes. Mild cytotoxic and moderate antiproliferative effects are to be expected in cultured keratocytes with a standard transduction procedure (8 micrograms/ml for 2 h).

Cell Division↗
PubMed1998

Epithelioid cell Spitz nevus of the eyelid.

PURPOSE: To report a 20-month-old child with a rapidly growing dome-shaped red nodule on the left lower eyelid. The lesion was diagnosed clinically as an hemangioma, but microscopy disclosed an epithelioid Spitz nevus. METHOD: Case report. RESULT: Histopathologic examination of the excised lesion disclosed a Spitz nevus (benign juvenile melanoma) of a chiefly epithelioid cell type. CONCLUSIONS: The differential diagnosis of eyelid skin nodules in children should include Spitz nevus. This uncommon nevus has many cytologic features in common with nodular malignant melanoma. Histologically, it may be difficult to distinguish between nodular malignant melanoma and Spitz nevus.

Diagnosis, Differential↗
PubMed1998

Retroviral vector-mediated gene transfer into keratocytes in vitro and in vivo.

PURPOSE: To determine the potential of somatic gene transfer as a technique for modulating corneal wound healing after superficial keratectomy. METHODS: The transduction of human and rabbit keratocytes with beta-galactosidase and herpes simplex virus thymidine kinase genes was performed. In vitro, human and rabbit keratocytes were transduced with retroviral vectors bearing beta-galactosidase or HStk (herpes simplex virus thymidine kinase) genes. In vivo, rabbit keratocytes were transduced by topical application of vector supernatant after a superficial keratectomy. In vitro and in vivo, expression of the beta-galactosidase gene was examined with histochemical staining. In vitro, ganciclovir cytotoxicity in HStk gene-transduced keratocytes and bystander effect in co-cultures of HStk(+) and HStk(-) keratocytes were measured by determining the degree of confluency of cells in 6-well plates after 10 days of incubation. Corneal haze in rabbits was measured after transduction with Hstk and subsequent treatment with topical ganciclovir. RESULTS: In vitro, both human and rabbit keratocytes were transduced successfully with both beta-galactosidase and HStk genes. Transduction efficiency was greater with human (22%) than with rabbit (16%) cells, and both HStk-transduced cell lines showed dose-dependent ganciclovir cytotoxicity and a significant bystander effect. In vivo, expression of beta-galactosidase within vimentin-positive corneal stromal cells confirmed transduction of keratocytes in the rabbit after superficial stromal keratectomy with an efficiency of 25% to 40%. Postoperative application of topical ganciclovir reduced corneal stromal haze in rabbits. CONCLUSIONS: The ability to genetically transduce stromal keratocytes provides a new strategy for understanding the important cellular and molecular events that influence corneal wound healing, thus offering a potential approach to decrease or prevent corneal haze and scarring after superficial keratectomy.

Animals↗