Biomedical subjects

B Seitz

Publications and source records attributed to B Seitz.

At least 55 records · Page 3Linked to original sources

PubMed2001

Posterior corneal curvature changes after myopic laser in situ keratomileusis.

OBJECTIVE: To assess the posterior corneal power and asphericity changes after myopic laser in situ keratomileusis (LASIK) and to correlate these changes with the amount of correction and the residual stromal bed thickness. DESIGN: Prospective nonrandomized (self-controlled) comparative study. PARTICIPANTS: Fifty-seven eyes of 14 women and 15 men, mean age at the time of surgery 33 +/- 9 (range, 19-53) years with a spherical equivalent (SEQ) of -1.00 to -15.50 (mean, -5.07 +/- 2.81) diopters (DI). INTERVENTION: All procedures were performed with the Keratom II Coherent-Schwind excimer laser and and the Moria Model One microkeratome (150-microm head). Subjective refractometry, Orbscan slit scanning corneal topography analysis and pachymetry were performed before and 3 months after LASIK for myopia (n=35, -1.00 to -15.50 D, mean -4.75 +/- -3.07 D) or myopic astigmatism (n=22, sphere 0.00 to -9.75 D, mean -4.75 +/- 2.36 D; cylinder -0.75 to -3.50 D, mean -1.68 +/- 0.86 D). Intended ablation depth ranged from 12 to 108 (mean, 48 +/- 22) microm. Topographic raw data were decomposed into a set of Zernike polynomials as published in detail previously, and parameters potentially indicative for detection of a "mild keratectasia" were derived. MAIN OUTCOME MEASURES: Posterior central corneal power and asphericity before and after LASIK were compared, and changes of these variables were correlated with the SEQ change (deltaSEQ)and the residual corneal bed thickness RBT). RESULTS: The mean RBT after LASIK was 280 +/- 42 microm. Overall, change of posterior power (-6.28 +/- 0.22 D/ -6.39 +/- 0.23 D, P=0.02) was statistically significant and change of asphericity (0.98 +/-0.07/1.14 +/- -.20, P<0.0001) was highly significant. In eyes with RBT < or =250 microm, the average change of posterior central power (-0.20 +/- 0.10 D vs. -0.08 +/- 0.18 D) was significantly greater than in eyes with RBT >250 microm (P=0.003). The change of posterior corneal power correlated significantly with deltaSEQ (P=0.004) and the RBT (P=0.002). CONCLUSIONS: Increased negative keratometric diopters and oblate asphericity of the posterior corneal curvature suggest that mild "keratectesia" of the cornea may be common early after LASIK. Further stuudies with longer follow-up are required to clarify whether this biomechanical deformation is progressive and whether a residual bed thickness of >250 microm can completely prevent it.

Adult↗

PubMed2001

Histopathologic findings in a transsclerally sutured posterior chamber intraocular lens.

A 77-year-old woman had penetrating keratoplasty (PKP), removal of an anterior chamber intraocular lens (IOL), and implantation of a transsclerally sutured posterior chamber IOL for painful pseudophakic bullous keratopathy. Postoperatively, preexisting anterior synechias led to painful secondary angle-closure glaucoma and the eye was enucleated 8 months after the PKP. Light microscopy of the eye revealed that the haptics of the IOL were surrounded by a variably dense fibrous membrane consisting of connective tissue and fibroblasts. In some areas, the haptics had eroded into the superficial stroma of the ciliary body. Except for rare foreign-body giant cells, no inflammatory cells were present near the haptics. This case illustrates that haptics of transsclerally sutured posterior chamber IOLs may be stabilized by fibrous membranes and/or by erosion into the ciliary body relatively soon after implantation. This should be considered if surgical centration, removal, or exchange of such a lens is planned.

Aged↗

PubMed2001

[Wavelet representation of corneal topography data after nonmechanical penetrating keratoplasty--a clinical study].

BACKGROUND: Corneal surface irregularities may limit the visual outcome after penetrating keratoplasty (PK). Corneal topographers mainly render empirically derived and system-specific statistical indices for characterization of superficial inhomogeneities which may lack clinical evidence and make inter-system comparisons difficult. The purpose of this study was to detect and quantify focal surface irregularities of the cornea after nonmechanical PK by 2-dimensional wavelet decomposition based on corneal topography data. PATIENTS AND METHODS: Our study included 15 patients with keratoconus and 10 patients with Fuchs' dystrophy with all-sutures-out after penetrating keratoplasty. For trephination we used the excimer laser MEL60 (Aesculap-Meditec, Germany) (7.5/7.6 mm diameter in dystrophies, 8.0/8.1 mm in keratoconus, double-running 10-0 nylon suture). After suture removal a complete ophthalmological examination including OrbScan topography analysis (Orbtec, USA) was performed. The refraction data were extracted via "data recorder" and decomposed using 2-dimensional wavelet analysis methods (Daubechies-4-wavelets on five scales of resolution). Corneal irregularities were quantified (scale 1 = fine details to scale 5 = coarse details). RESULTS: All detail coefficients (horizontal, vertical and diagonal) correlated statistically significant with the "Irregular Astigmatism" provided by the OrbScan-system (p < 0.05). In scale 3 and 4 a relative maximum of the wavelet detail coefficients occurred, whereas the coefficients at scale 2 and 5 were significantly smaller. The horizontal and vertical detail coefficients correlated significantly inversely with the best-corrected visual acuity (p < 0.04). All detail coefficients were significantly lower in the patient group with keratoconus compared to Fuchs' dystrophy. CONCLUSIONS: Wavelet decomposition of corneal topography refraction data allows an analytical isolation and quantification of focal corneal superficial irregularities. This algorithm is independent of the currently used topography system and allows a smoothing of the raw data set adapted to scale of resolution and data compression.

Adult↗

PubMed2001

[Standardized semiquantitative analysis of corneal neovascularization using projected corneal photographs--pilot study after perforating corneal keratoplasty before immune reaction].

BACKGROUND: A semiquantitative scheme for analysis of corneal neovascularization using projected corneal photographs is demonstrated and tested in a pilot study to analyze occurrence of corneal neovascularization in patients after perforating keratoplasty which subsequently developed transplant rejection. METHODS: Corneal photographs on the slit lamp with diffuse frontal illumination were obtained in a standardized technique. Slides were projected with 100 x magnification and analyzed twice with a 2 months interval. Corneal vessels were graded by two independent observers in each of 12 corneal sectors in a standardized fashion (grade 0: no vessels beyond limbus, 1: vessels between limbus and outer end of a double-running diagonal suture; 2: vessels between outer suture end and graft-host junction; 3: vessels reaching graft-host junction; 4: vessels within donor cornea). All patients with endothelial graft rejection of the prospective Erlangen non-high-risk keratoplasty study were included in a pilot study (1/1997-6/2000: 13 of 325; 4%). One patient without photographs available was excluded. Corneal photographs taken prior to surgery (n = 10), at the last 3 monthly-routine control before (10), at rejection episode (12) and one year later (10) were evaluated for corneal neovascularization. RESULTS: Interobserver correlation at the two assessments was 0.79 and 0.86 (Kendall's Tau B). Correlation between the assessments at the two analyses 2 months apart was 0.8. New vessels with diameter up to 6 microns can be detected. 8 of 12 analyzed patients (67%) with immune reaction after keratoplasty developed corneal neovascularization within 1 year after operation prior to transplant rejection in at least one corneal sector (2.1 +/- 1.9 sectors; 1-6). At time of rejection, new vessels reached the graft-host junction in 2 patients, in 1 patient vessels grew into the donor cornea, whereas in 8 the vessels were seen beyond the outer suture end without reaching host-graft junction (grade I: 1 patient). New vessels usually pointed to the outer suture ends of the double-running suture. CONCLUSIONS: Development of corneal neovascularization e.g. after keratoplasty can be assessed reliably using projected slides of corneal photographs at 100 x magnification. This method has the advantage of being more objective, precise and available compared to simple evaluation at the slit lamp. Postkeratoplasty corneal neovascularization seems to be common in non-high-risk eyes later developing transplant rejection. However, new vessels usually do not reach the host-graft junction. Whether neovascularization after keratoplasty demonstrates a risk factor for subsequent transplant rejection remains to be analyzed in a greater study.

Cornea↗

PubMed2001

[Visual rehabilitation and intraocular pressure elevation due to immunological graft rejection following penetrating keratoplasty].

PURPOSE: Endothelial graft rejection and intraocular pressure elevation are the most common causes of graft failure following penetrating keratoplasty (PK). Aim of this study was to evaluate the visual rehabilitation and the development of intraocular pressure during and after graft rejection. PATIENTS AND METHODS: The study included 20 eyes of 20 patients (age 54.7 +/- 19.8 years) with endothelial graft rejection, that fulfilled the following inclusion criteria 1) graft rejection was diagnosed and treated in our department; 2) at least one year follow-up after graft rejection; 3) avascular corneal pathology. The mean follow-up was 23 +/- 14 months. According to the type of surgical procedure patients were classified in PK only (n = 15, one after cataract extraction), PK combined with extracapsular cataract extraction and intraocular lens (IOL) implantation (n = 1); PK combined with secondary IOL-implantation or IOL-exchange (n = 4). Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection und then regularly in a defined examination raster in an out-patient service with cornea specialization. RESULTS: The time interval between first symptom of 18 acute diffuse and 2 chronic focal graft rejection and start of treatment was 9 +/- 13 days. Best-corrected visual acuity (CVA) was 0.6 +/- 0.2 before graft rejection and decreased significantly at the time of diagnosis (0.2 +/- 0.2; p = 0.001). Six weeks after graft rejection CVA was 0.5 +/- 0.2 and remained almost stable until one year after rejection (0.6 +/- 0.3) in 16 patients with reversible graft rejection. Only 4 patients (20%) showed an irreversible graft failure requiring Re-PK. Intraocular pressure (IOP) was not elevated in 75% of the patients (n = 15) and did not need any antiglaucomatous treatment during and after the rejection phase. In 5 eyes (25%) (3 after PK combined with anterior chamber IOL-explantation and secondary posterior chamber IOL-implantation; 1 with secondary pseudoexfoliation glaucoma and 1 steroidal responder) IOP was elevated during graft rejection (26 +/- 7 mmHg), but was controlled by intensive topical antiglaucomatous treatment. CONCLUSION: Typically, the visual rehabilitation after graft rejection was good if the clinical signs were diagnosed just in time and treated adequately. There is no direct correlation between graft rejection and intraocular pressure elevation. However, the development of intraocular pressure elevation seems to be strongly associated with preexisting glaucoma, preexisting anterior synechiae and/or simultaneous anterior chamber lens implant removal. A careful patient management after PK plays an important role to prevent the development of irreversible graft failure due to graft rejection.

Acute Disease↗

PubMed2001

[Effect of pupil size on longitudinal focal distribution after photorefractive keratectomy ].

BACKGROUND: Optical aberrations induced by the transition zone of a myopic photorefractive keratectomy (PRK) may degrade the image quality. The subjectively evaluated visual acuity and contrast sensitivity may be reduced significantly especially with mydriasis. The purpose of this study was to calculate the image forming properties of the eye using raytracing techniques of a spot light source based on topographic height data of a scanning slit videokeratoscope. METHODS: Refractive surfaces were calculated from raw height data sets of the anterior and posterior corneal surface measurements (Orbscan, Orbtec, USA). The characteristics of the residual refractive surfaces were derived from Navarro's eye model. The focal distance was calculated using the exact raytracing calculation. Point spread function was determined at the focal plane and at 5 (delta = 0.2 mm) parafocal planes in front of and behind the focal distance in accordance to the pupil diameter (2, 3 and 6 mm). The algorithm was applied to 11 selected eyes (6 left, 5 right) of 8 patients before and after PRK with myopia (n = 6) and myopic astigmatism (n = 5). RESULTS: Before PRK the focal distance did not decrease significantly with increasing pupil size (2 to 6 mm), but decreased significantly after PRK (-0.41 +/- 0.12 mm, p = 0.02). Preoperatively, the variance of the point spread function did not differ significantly between a 2 mm (0.046 +/- 0.015 mm) and a 6 mm (0.055 +/- 0.021 mm) pupil size but was affected significantly by the pupil size postoperatively (2 mm: 0.049 +/- 0.018 mm, 6 mm: 0.096 +/- 0.045 mm, p = 0.04). CONCLUSIONS: Raytracing of corneal topography height data based on refined eye models with the option of calculation of the focus has the potential of tracing the optical resolution of the eye as a function of the pupil size. Due to of the altered surface geometry of the cornea after myopic PRK, both the variance of the point-spread function and the depth of focus increase with pupil size. This may be an explanation for impaired subjective refractometry and reduced contrast sensitivity of the patient after conventional keratorefractive surgery.

Adult↗

PubMed2001

[Multilayer amniotic membrane transplantation for corneal ulcers not treatable by conventional therapy - a prospective study of the status of cornea and graft during follow-up].

PURPOSE: The purpose of this prospective clinical study was to evaluate the condition of the cornea (epithelium and vascularization) and the membrane presence and retraction during follow-up after amniotic membrane transplantation in patients with persistent corneal ulcers. PATIENTS AND METHODS: Between June 1999 and November 2000 AM transplantation was performed in 30 consecutive patients (average age 59 +/- 17 years) with corneal ulcers refractory to clinical treatment. We evaluated the clinical diagnosis, localisation, size and depth of the ulcers, condition of the ocular surface and visual acuity before and after surgery. After complete removal of the epithelium and pannus, one (n=11), two (n=17) or three (n=2) layers of amniotic membrane were fixed with multiple interrupted sutures, depending on the depth of the lesion. A therapeutic contact lens was applied in most eyes and removed after one month. The most frequent diagnoses were chemical burn (5 x lime, 1 x lye and 1 x liquid aluminium), 7 x herpes, 3 x polyarthritis and 3 x blepharo-keratoconjunctivitis in neurodermitis. The ulcers had a medium length of 4.9 +/- 3.2 mm, a width of 3.5 +/- 3.0 mm and a depth ranging between 30 % and 95 % (68 +/- 21 %). RESULTS: Complete epithelial closure was achieved in 27 of 30 eyes (90 %). In 4 eyes a recurrent epithelial defect occurred after initial closure. At the 1-, 3- and 6 month follow-up the amniotic membrane was present in 93 %, 73 % or 30 %, respectively, but was more or less retractet in 52 %, 58 % or 67 %, respectively. A complete corneal epithelium was noted in 79 %, 89 % or 90 % of eyes, respectively. However, corneal neovascularization was observed in 24 %, 58 % or 60 % of eyes. Visual acuity was </= 20/400 in 60 % eyes preoperatively, but in 69 % after 3 months and in 78 % after 6 months of follow-up. CONCLUSION: In persistent corneal ulcers, amniotic membrane transplantation should be considered in early stages to achieve permanent epithelial closure in a less inflamed eye thus avoiding penetrating keratoplasty à chaud or conjunctival flaps. However, in eyes with broad descemetocele especially following chemical burns, this treatment modality does not seem to be effective.

Adult↗

PubMed2001

[First results of implantation of a new, potentially accommodative posterior chamber intraocular lens].

PURPOSE: Conventional posterior chamber intraocular lenses (PCIOL) generally provide excellent visual acuity but do not restore accommodation. A new, potentially accommodative PCIOL has been designed after principles elaborated by K.D. Hanna using finite element models. However, before newly developed PCIOL may be implanted routinely in larger numbers of patients, careful and meticulous evaluation in clinical studies is necessary. Thus, it was the aim of this study to investigate intra- and early 3-month postoperative findings after implantation of the newly designed PCIOL. PATIENTS AND METHODS: In a prospective pilot and safety study that was approved by the ethics committee of our university, six eyes of six patients (2 males, 4 females, age range 54 to 87 years) with senile or presenile cataract underwent phacoemulsification and implantation of the new PCIOL by one surgeon between June and November 2000. The PCIOL (1 CU, HumanOptics AG, Erlangen, Germany) is a one-piece hydrophilic acrylic foldable lens with an optic diameter of 5.5 mm. Modified haptics are intended to allow anterior movement of the lens optic as a function of contraction of the ciliary muscle. Intra- and early postoperative findings obtained after one and two days, one, two and six weeks and 3 months postoperatively were documented prospectively. Postoperative examinations included recording of distance and near visual acuity both obtained with best distance correction, determination of subjective near point and measurement of distance and near refraction by streak retinoscopy. Follow-up was at least three months in all patients. RESULTS: Surgery was uncomplicated in all patients with successful in-the-bag implantation and good centration of the PCIOL. The postoperative course was uncomplicated without inflammation, hemorrhage, synechiae or decentration. Visual acuity improved in all patients according to the status of the macula with values between 20/200 (atrophic maculopathy) and 20/20. After three to six months we observed a difference between retinoscopic near and distance refraction of 0.625 to 1.875 D and subjective near points of 40 to 100 cm. Near visual acuity with distance correction ranged from 0.1 or J 16 (atrophic maculopathy) to 0.4 or J 7. CONCLUSIONS: These early and preliminary results of our small pilot study are encouraging. Our findings may indicate at least some degree of pseudophakic accommodation. However, further studies with additional methods of measurements, with longer follow-up, more patients and controlled studies with control groups are essential to further determine safety and potential accommodative power of this new PCIOL.

Accommodation, Ocular↗

PubMed2001

[Impact of pterygium size on corneal topography and visual acuity - a prospective clinical cross-sectional study].

PURPOSE: Pterygia may cause topographic changes featuring increase of astigmatism. The purpose of this study was to quantify the impact of the head-limbus-distance (=height) and limbal base length of the pterygium on the anterior corneal curvature and visual acuity before excision. PATIENTS AND METHODS: In 52 eyes (19 female, 33 male) with a mean age of 53 +/- 14 years the pterygium size (height, base length, area) was quantified using projected preoperative clinical slides and was correlated with visual acuity, refractive, keratometric, topographic astigmatism and Surface Regularity Index (SRI), Surface Asymmetry Index (SAI) of the TMS-1 videokeratoscope. RESULTS: The mean height of the pterygium was 3.1 +/- 1.4 (0.8 to 6.7) mm, the mean base length was 5.1 +/- 1.4 (2.9 to 7.8) mm, the estimated mean area was 11.4 +/- 6.9 (2.1 to 29.4) mm(2). The increasing pterygium height and area resulted in a highly significant elevation of the preoperative SRI and SAI values (p </= 0.01). The amount of keratometric (p=0.02) and topographic astigmatism (p=0.001) correlated significantly with height and area of the pterygium. In addition, pterygium size correlated significantly with the differences of zonal corneal power between steepest and flattest hemimeridian in the 3-mm zone or 5-mm zone, respectively (p </= 0.01). Best-corrected visual acuity and height/area of the pterygium correlated significantly inversely (p=0.001). Visual acuity seemed to be mostly unaffected up to a height of 2.5 mm. Overall, the impact of the base length was much less striking. Topographic astigmatism (3.3 +/- 2.8 D) was significantly larger than keratometric astigmatism (2.1 +/- 2.1 D) (p=0.001). The larger the pterygium, the larger was the difference between keratometric astigmatism and subjectively tolerated spectacle cylinder (p </= 0.01). CONCLUSIONS: Increasing distance of the pterygium head from the limbus results in increased amount and irregularity of preoperatively induced corneal astigmatism. This may explain the patient's decrease in visual acuity before the pterygium reaches the optical axis. Our data may help to determine the adequate time point for primary pterygium excision.

Adult↗

PubMed2001

[Primary open angle glaucoma in cornea plana masked by false normal applanation tonometry (Goldman) - a case report].

BACKGROUND: Cornea plana is a rare syndrome, which leads to a flat corneal curvature due to a reduced sclero-corneal angle. Depending on the regularity of the corneal astigmatism the frequently resulting hyperopia may be difficult to compensate for. Because of the flatness of the cornea the anterior chamber is also flat, the anterior chamber angle can be restricted, and the applanatory intraocular pressures (IOPs) are measured too low. A primary open angle glaucoma is therefore not diagnosed for a long time, until changes of the optic nerve head occur. Patient and methods We report on a 66-year-old male with cornea plana. Although his intraocular pressure (IOP), measured with an applanation tonometer (Goldmann), had always been normal (< 21 mm Hg), he suffered from an increasing glaucomatous atrophy of the optic disc. We carried out a complete ophthalmological investigation, including keratometry and corneal topography analysis (TMS-1, Tomey). Furthermore, visual field was determined (G1, Octopus) and the optic nerve heads were documented and analysed by papillometry. A 48-hour tension profile was worked out for both eyes including applanation and Schiötz tonometry. Results The central refractive power of the cornea was 31 diopters and the cornea seemed to be flattened on slit lamp evaluation. The glaucomatous atrophy of the optic disc was more pronounced in the OD than in the OS (OD=neuroretinal rim loss in the upper part, at the bottom and in the lateral part of the optic disc, OS=laterally distinct neuroretinal rim loss). While the anterior parts of the eye were shortened (depth of the anterior chamber was OD/OS=1.9 mm), a macrophthalmus posterior was stated (axial length OD=25.78 mm, OS=25.72 mm). However, the IOPs were measured below 21 mm Hg by applanation during the entire tension analysis, comparable values measured with the Schiötz tonometer showed values above 21 mm Hg. We converted the applanatory IOP values according to the flat corneal power, as described in literature (addition of 1 mm Hg to the applanatory values per 3 diopters decreased corneal power). The tension analysis now showed increased values, as expected after observation of the glaucomatous excavated optic nerve head. Conclusion In patients with cornea plana applanatory IOPs are measured too low. Therefore in case of very flat corneas a mathematical correction of the applanatory IOP should be carried out, in order to diagnose a primary open angle glaucoma early enough.

Aged↗

PubMed2001

[Immunological graft reactions after penetrating keratoplasty - A prospective randomized trial comparing corneal excimer laser and motor trephination].

BACKGROUND AND PURPOSE: Nonmechanical trephination has been established as an advantageous procedure in penetrating keratoplasty (PK) for avascular corneal diseases and has been performed successfully in more than 1000 eyes at our institution. The purpose of this study was to compare incidence, type and reversibility of immunological graft reactions after mechanical and nonmechanical trephination for PK. PATIENTS AND METHODS: As part of a prospective randomized clinical trial 179 eyes of 76 females and 103 males were included, that had primary central PK without previous intraocular surgery between 10/1992 and 12/1997 for Fuchs' dystrophy (diameter 7.5 mm, n=73) or keratoconus (8.0 mm, n=106). The recipient and donor trephinations were performed from the epithelial side using either a motor trephine (Microkeratron, Geuder, n=91) or an 193-nm excimer laser (MEL60, Aesculap-Meditec, 1.5 x 1.5 mm spot mode, 16 - 24 mJ/pulse, repetition rate 25/s) along round metal masks with 8 "orientation teeth/notches" (n=88). As a routine, donor oversize was 0.1 mm. 128 patients (72 %) had PK only, 51 patients had simultaneous cataract extraction and PC-IOL implantation (triple procedure). Wound closure was achieved using a 16-bite double running diagonal suture by one surgeon (G.O.H.N.). In 53 % of procedures short-term-preserved donor tissue, in 47 % organ-cultured tissue was used. The mean patient/donor age was 51 +/- 17/57 +/- 19 years with nonmechanical trephination and 50 +/- 19/58 +/- 20 years with mechanical trephination. Incidence, type and reversibility of endothelial immunologic graft reactions were recorded continuously by clinical follow-up in an outpatient service with cornea specialization (after 6 weeks, then every 3 months until after suture removal, then every half year). RESULTS: During a mean follow-up of 40 +/- 15 months, 7.3 % of eyes developed an immunological endothelial graft reaction. Acute diffuse (5.6 %) were more frequent than chronic focal reactions (1.7 %). Only 1.7 % of grafts became irreversibly cloudy. More than 80 % of all graft reactions occurred later than one year (on average 23 +/- 13 months) after PK. Neither incidence (p=0.82, Chi square test) nor cumulative 3-year-rate of immunological graft reactions (p=0.91, LogRank test) differed significantly comparing nonmechanical (6.8 % or 7.3 %) and mechanical (7.7 % or 5.6 %) trephination. In eyes with keratoconus (6.6 %, 16 +/- 8 months) graft reactions did not occur more frequently (p=0.68) but earlier (p=0.02) than in eyes with Fuchs' dystrophy (8.2 %, 31 +/- 11 months). Donor age, post-mortem-time and preservation period did not significantly affect the rate of graft reactions in our study setting. CONCLUSIONS: Besides well-established optical advantages, nonmechanical trephination using the excimer laser seems to have no immunologic drawbacks in contrast to conventional mechanical trephination. Donor parameters appear to have no major impact on the incidence of graft reactions after non-high-risk PK. Rather, an adequate postoperative therapy with topical steroids, an informed patients' compliance, a consequent long-term follow-up in a clinical out-patient service with corneal specialization and a good education of and cooperation with the referring ophthalmologists are of utmost importance for the clear corneal graft in the long run.

Adolescent↗

PubMed2001

[Autologous serum for otherwise therapy resistant corneal epithelial defects - Prospective report on the first 70 eyes].

PURPOSE: The purpose of this prospective clinical pilot study was to evaluate the efficiency, practicability and safety of topical autologous serum for therapy resistant corneal epithelial defects. METHODS: Between November 1999 and June 2001 autologous serum therapy was applied in 70 eyes of 67 consecutive patients (age 18 to 92 [average 59 +/- 18] years) with corneal epithelial defects refractory to standard clinical treatment at the Department of Ophthalmology University Erlangen-Nürnberg. We evaluated localization, size of the defect, time until epithelial wound closure and the incidence of recurrences in relation to the clinical diagnosis. The blood was obtained by venipuncture, centrifuged and the non-diluted serum was filled in sterile bottles, kept in the + 4 (o)C refrigerator and hourly applied during daytime. Simultaneous systemic and topical medication depended on the underlying disease. RESULTS: In 45 eyes corneal epithelial defects appeared after penetrating keratoplasty but in 25 eyes corneal epithelial defects were not related to a corneal transplant. The epithelial defect had a medium length of 4.2 +/- 2.4 mm and a width of 3.0 +/- 1.8 mm. Previously, the patients had been treated with maximal topical therapy (including hyaluronic acid) for 13 +/- 11 days. Treatment with autologous serum lasted from 4 to 45 (mean 16 +/- 11) days. A complete corneal re-epithelialization was achieved in 57 of 70 eyes (81 %) after 3 to 45 (mean 15 +/- 12) days. Forty-eight of these 57 eyes (84 %) had no recurrence during a follow-up of 12 +/- 4 months. In 9 eyes (16 %) a recurrent epithelial defect occurred one or two months after initial closure. These eyes were treated successfully with a second autologous serum therapy (6 x), amniotic membrane transplantation (2 x) or repeat keratoplasty (1 x). Thirteen eyes (19 %) without primary success of autologous serum applied for 11 to 50 days were finally treated successfully with amniotic membrane transplantation (10 x) or repeat keratoplasty (3 x). CONCLUSION: In persistent corneal epithelium defects, autologous serum therapy can be considered as an effective and practicable therapy without adverse reactions. Especially in eyes after complicated penetrating keratoplasty the prognosis may be improved and more invasive treatment modalities such as botulinum toxin injection, amniotic membrane transplantation or (repeat) penetrating keratoplasty may be avoided. Definitive determinants for the success of this novel therapy have not been identified, yet. However, eyes with accompanying deep stromal defects do not seem to be good candidates.

Adolescent↗

PubMed2001

In vitro effects of antiviral agents on human keratocytes.

PURPOSE: To study the effects of antiviral agents on human keratocytes in vitro. METHODS: Cultured human keratocytes were incubated with either ganciclovir, idoxuridine, trifluridine, or cidofovir at concentrations from 0.0001 to 10 mg/mL. Phase-contrast microscopy and XTT (sodium [2,3-bis [2-methoxy-4-nitro-5-sulphophenyl]-2h-tetrazolium-5-carboxanilide, inner salt) colorimetric assay were performed after 24, 48, and 72 hours of incubation. RESULTS: When adjustments were made for time of incubation and concentration, trifluridine reduced cell viability significantly more than ganciclovir, idoxuridine, and cidofovir (p<0.001, three-way analysis of variance). There was significant time-and dose-dependent reduction of cell viability (p<0.001) with trifluridine and cidofovir. After a 72-hour incubation with ganciclovir or idoxuridine, cell viability was reduced as compared with 24- and 48-hour incubation (p<0.001); only the effects of the highest concentration tested (1.0 mg/mL) were significantly different from those of the lower concentrations (p<0.002). At a concentration of 1.0 mg/mL, trifluridine and cidofovir produced moderate to severe signs of cytotoxicity, whereas ganciclovir and idoxuridine displayed much less severe morphologic signs. CONCLUSIONS: Our results indicate that antiviral agents may have both time- and concentration-related toxic effects on stromal keratocytes. These findings may impact the selection of the most appropriate antiviral drug when it is needed to treat infections involving the corneal stroma.

Antiviral Agents↗

PubMed2001

Scanning-slit and specular microscopic pachymetry in comparison with ultrasonic determination of corneal thickness.

PURPOSE: To determine the central corneal thickness values in healthy eyes with the recently developed Orbscan scanning-slit system, contact and noncontact specular microscopic pachymetry and compare the results to conventional ultrasonic pachymetry. METHODS: In the following sequence, Orbscan, Topcon SP-2000P noncontact specular microscope, AL-1000 ultrasound, and Tomey contact specular microscope were used to record thickness values. Thirty-four healthy right corneas of 34 healthy subjects were investigated. RESULTS: Orbscan pachymetry correlated significantly with ultrasound (r = 0.64, p < 0.001), contact (r = 0.45, p < 0.001), and noncontact specular microscopy (r = 0.72, p < 0.001). Likewise, the Topcon SP-2000P noncontact specular microscopy pachymetry disclosed similar statistical results compared with ultrasound (r = 0.88, p < 0.001), and contact specular microscopy pachymetry (r = 0.76, p < 0.001). The mean central corneal thickness results were significantly higher ( p < or = 0.01) than ultrasonic values (580 +/- 43 microm) using the contact specular microscope (640 +/- 43 microm) or Orbscan system (602 +/- 59 microm) but were significantly lower ( p < 0.001) using the noncontact specular microscope (547 +/- 49 microm). CONCLUSIONS: The results indicate that the devices tested cannot be simply used interchangeably. For long-term patient follow-up, one specific instrument is recommended. Recently developed pachymetry machines are especially helpful when additional corneal data such as thickness profile, elevation maps, anterior chamber depth, and endothelial morphology are required.

Cornea↗

PubMed2000

[Development of endothelial cell number in the host corneal endothelium. Status after block excision and eccentric corneal scleroplasty].

PURPOSE: Block excision of anterior uveal tumors and cystic epithelial ingrowth to the anterior chamber is a curative treatment for morphological rehabilitation of the globe. This study quantified the course of the host corneal endothelium after this peripheral corneoscleral graft. PATIENTS AND METHODS: This retrospective cross-sectional study examined 53 specular microscopic photographs of the central host cornea in 30 patients. The diameter of the block excision was 8.5 +/- 1.9 mm (6.0-11.0 mm). Follow-up after surgery averaged 37.9 +/- 47.6 months (1-216). RESULTS: The corneal endothelial cell count decreased with the duration of follow-up after block excision. The cell count was not related to indication for surgery or to diameter of block excision. Mean visual acuity was 16/20 before block excision and 6/20 at the end of follow-up. CONCLUSION: There is a significant loss of endothelial cells of the host after block excision, requiring a second central penetrating keratoplasty in some patients. Loss of endothelial cells may be due to the surgical trauma, chronic immunological reaction against the donor endothelium, or migration of the host endothelial cells onto the corneoscleral graft.

Adult↗

PubMed2000

Correlation among refractive, keratometric and topographic astigmatism after myopic photorefractive keratectomy.

BACKGROUND: Photorefrative keratectomy can be used to flatten the curvature of the anterior cornea and reduce the myopic refraction of the eye. This leads to unphysiological topographical changes of the cornea and may alter the conditions for examinations of corneal surface topography. The purpose of this study was to check for mutual agreement of three different methods of assessment of astigmatism before and after myopic photorefractive keratectomy (PRK). PATIENTS AND METHODS: Forty-seven eyes of 28 patients (age 32.7+/-6.6 years) following PRK using an 193-nm excimer laser were included in this study. 37 eyes were treated for pure myopia (-4.9+/-2.4 D) and 10 eyes for myopic astigmatism (sphere -2.0 to -7.0 D, cylinder -1.0 to -3.0 D). Preoperatively and at 18 months postoperatively, subjective refractometry, keratometry and topography analysis were performed. The axes of topographic and keratometric cylinder were standardized periodically (180 degrees) with respect to the refractive cylinder axis. RESULTS: Pre- and postoperatively, the absolute astigmatism values correlated highly significantly between all three methods (P< or =0.001). The mean refractive cylinder was 0.65+/-0.61 D preoperatively and 0.46+/-0.41 D postoperatively (P=0.2). The mean keratometric astigmatism was 1.14+/-0.64 D before and 0.94+/-0.50 D after PRK treatment (P=0.2). Among the three methods, the mean topographic astigmatism was the highest (P<0.001) preoperatively (1.31+/-0.56 D) and postoperatively (1.21+/-0.52 D) (P=0.3). In eyes treated for pure myopia, no difference between pre- and postoperative refractive, keratometric and topographic astigmatism was detected (P>0.5). The axes of both topographic and keratometric astigmatism correlated highly significantly with the refractive cylinder axis (R> or =30.9, P<0.0001). CONCLUSION: Up to 2 years after myopic PRK, the difference between refractive and keratometric astigmatism does not differ from the preoperative value, indicating an even corneal surface. The absolute astigmatism values and the cylinder axis correlated well between subjective and objective methods of astigmatism assessment. Thus, objective measurements may be helpful in determining the cylinder component of best spectacle correction after PRK. However, topographic analysis overestimates astigmatism values systematically before and after PRK.

Adult↗

PubMed2000

Thermal load of laser aperture masks in nonmechanical trephination for penetrating keratoplasty with the Er:YAG laser: comparison between stainless steel and ceramic masks.

PURPOSE: Thermal effects on the laser aperture mask may play a major role in the thermal loading of the cornea during nonmechanical trephination in penetrating keratoplasty. The purpose of this study was to assess the temperature increase on the laser mask using the 2.94-microm Er:YAG laser in order to find suitable parameters for avoidance of thermal damage to the cornea. METHODS: Thermal load measurements were performed on donor (7.5 mm trephination diameter, 0.7 mm thickness, central hole 3.0 mm) and recipient (7.5 mm trephination diameter, 0.7 mm thickness, outer diameter 13.0 mm) aperture masks. The masks were either mounted on a thermal isolator or fixed directly on porcine corneal samples. Temperature increase was measured either under static conditions in the ablation area (setup 1) and at the opposite side of the mask (setup 2) or in the ablation area under dynamic conditions, rotating the whole globe to simulate a constant trephination speed with the mask positioned directly on a porcine cornea (setup 3). We used the NWL Er:YAG solid-state laser in a 1.3-mm free-running spot mode focused on the trephination margin (half of the beam on the mask and half of it on the cornea) with a pulse energy of 200 or 400 mJ and 18CrNi10 stainless steel versus three different types of ceramic masks (silicium carbide, silicium nitrite, aluminum oxide). Temperature was assessed using an infrared pyrometer with automatic data acquisition software for a personal computer. RESULTS: Overall, the temperature rise ranged between 43.6 K (metal donor mask at the trephination area with 400 mJ pulse energy) and 3.3 K (silicium carbide recipient mask at the opposite side of the mask with 200 mJ pulse energy). With all setups and both energy levels, the heating of the metal mask was significantly higher (P<0.02) than the heating of the three types of ceramic masks. The silicium carbide masks revealed the lowest temperature rise. Comparing the three setups, the temperature rise was maximal under static conditions in the ablation area and minimal at the opposite side, with the dynamic setup ranging in between. Temperature rise was significantly greater (P<0.04) in donor masks than in recipient masks for each mask material and both energy levels. CONCLUSION: The physical characteristics of silicium carbide masks seem superior to those of metal masks with regard to minimizing the thermal load of the epithelium or superficial stroma during Er:YAG laser trephination of the cornea for penetrating keratoplasty.

Animals↗

PubMed2000

Experimental evaluation of two current-generation automated microkeratomes: the Hansatome and the Supratome.

PURPOSE: To compare flap dimensions, cut quality, and blade deterioration after reuse in an experimental setting using two current-generation microkeratomes for laser-assisted in situ keratomileusis. METHODS: Two pivoting-head principle microkeratomes, the Hansatome and the Supratome, were used to perform a corneal flap in 50 freshly enucleated pig cadaver eyes, with an intended thickness of 160 microm. Provided stainless steel blades were used from one to five times. Flap diameter was measured by planimetry and thickness calculated using ultrasonic pachymetry at three different locations. Scanning electron microscopy of stromal beds and blades' cutting edges were performed to assess the cut and blade deterioration after repeated use. RESULTS: Mean flap central thickness (Hansatome/Supratome) was 151 microm (SD 18)/192 microm (SD 32). Progressive thinning/thickening of the flap was observed in the direction toward the hinge (P = .003/P = .021). Mean vertical flap diameters of 8.9 mm (SD 0.3)/8.0 mm (SD 0.4) differed significantly (P = .001). No correlation was found between thickness and diameter (r = 0.03, P = .935/r = 0.12, P = .603). At scanning electron microscopy, smooth cuts were observed with both keratomes using a new blade. Periodical chatter lines at keratectomy edge were present and were more pronounced after blade reuse. Cut quality, blade deterioration, and small tissue remnants on the blade surface were noted with repeated blade use, especially using the Supratome. CONCLUSIONS: Local flap thickness and flap diameter variations are inherent to the instrument used. Comparable cut-surface quality can be obtained with new blades. Although cut and blade deterioration appears to be minor after two reuses, the presence of tissue remnants on the blade surface still limits its reuse.

Animals↗