Biomedical subjects

A Langenbucher

Publications and source records attributed to A Langenbucher.

At least 19 recordsLinked to original sources

PubMed2006

[Evaluation of dynamic contour tonometry in penetrating keratoplasties].

PURPOSE: The PASCAL dynamic contour tonometer (DCT) adapted to the corneal geometry is a new approach for digital measurement of intraocular pressure (IOP). The purpose of this study was to evaluate the DCT vs Goldmann applanation tonometry (GAT) in penetrating keratoplasties. METHOD: We included 92 consecutive eyes after penetrating keratoplasty (57 without sutures, 32 with 2 running sutures, 3 with 1 running suture) in this prospective cross-sectional study. The mean outcome measurements were central corneal power (Zeiss ophthalmometer) and central corneal thickness (ultrasound pachymetry Tomey AL-1000). IOP was evaluated in consecutive measurements including 3x DCT and 1x GAT. RESULTS: The mean IOP measured with DCT was 18.3+/-4.0 mmHg in contrast to GAT with 14.3+/-4.1 mmHg (p<0.001). Both methods showed a strong correlation of IOP values (r=0.74, p<0.001). The quality of measurement in keratoplasties after complete suture removal was between Q1 and Q3 in 88% with DCT in contrast to 59% with two running sutures. Three values with a reproducibility of 0.97 (Cronbach's alpha) could be obtained in 53 eyes without sutures and with a reproducibility of 0.94 (Cronbach's alpha) in 20 eyes (62.5%) with 2 running sutures. DCT or GAT did not correlate with central corneal thickness. The mean astigmatism did not differ between keratoplasties without sutures (4.86+/-3.35 D) or with two running sutures (4.2+/-2.8 D, p=0.38). CONCLUSIONS: The DCT provides reproducible IOP measurements in penetrating keratoplasties with significantly higher values in comparison to GAT. Nevertheless, as known for GAT, postoperative intrastromal corneal sutures after penetrating keratoplasty disturb the exact DCT measurement as well.

Equipment Design↗

PubMed2006

[Accommodation ability under the aspect of refractive, demographic, and biometric parameters].

PURPOSE: The aim of this study was to evaluate the accommodation ability in healthy phakic eyes in relation to refraction and biometric parameters in order to get comparable results for patients with the accommodative 1 CU posterior chamber lens. METHODS: The study included 120 normal eyes of 120 patients (77 males, 43 females, mean age: 40+/-18, range: 11-70 years). The inclusion criteria were spherical equivalent for distance refraction <2 D, astigmatism <1.5 D, and a best-corrected visual acuity > or =0.8. Exclusion criteria were diabetes, glaucoma, cataract, traumas, or previous surgery. Subjects were divided into six age groups at increments of 10 years. Each group consisted of 20 subjects. Measurements included subjective and objective refraction (D), the accommodation ability (D) assessed with an accommodometer, and biometric parameters using the IOLMaster. In addition, the relation of anterior chamber depth and length of the eye was calculated for analyzing the relationship of anterior eye segment and accommodation. RESULTS: The spherical equivalent for distance refraction was 0.04+/-0.6 D with a range of -1.5 to 2.0 D. There was no sex-related significant difference of accommodation range. The accommodation range (D) decreased significantly with increasing age (p<0.0001, r=-0.895). The highest decrease could be found between the ages of 30 and 50 years. In subsequent years, the decline in accommodation ability was comparatively less. In association with the anterior chamber depth and the relation of anterior chamber depth and length of the eye, the accommodation ability fell with increasing age (p<0.001). The length of the eye did not correlate with the accommodation ability (p=0.8). CONCLUSION: There is a strong relationship between accommodation ability and age. Accommodation ability decreases strongly from the 3rd to the 5th decade; after that the loss of accommodation ability is relatively lower. The increase in lens thickness during the life span can implicate a correlation between the change of anterior chamber depth in relation to the length of the eye and a decrease of accommodation ability. Our results confirm Duane's hypothesis of accommodation and age.

Accommodation, Ocular↗

PubMed2006

[Impact of the eye's cyclorotation on axial orientation analysis of toric intraocular lenses: recommendations for an optimized evaluation of rotational stability of toric IOLs].

BACKGROUND: After the implantation of toric intraocular lenses (tIOLs) significant postoperative tIOL rotation angles were measured occasionally. We investigated the rotational stability of eyes during standardized photography and recommend two methods for an enhanced evaluation of tIOL rotation. PATIENTS AND METHODS: 1. The cyclorotation of the eye was investigated using standard fundus photography. A sequence of two fundus photographic slides was taken in 550 phakic eyes of 275 consecutive patients with a time interval of at least 6 months. With characteristic markers on the fundus photograph, the axial orientation of the eyes was defined and the cyclorotation between the two slides of each eye was measured. 2. Using bifocal photography (HRA II - Heidelberg Retina Angiograph), a sequence of anterior segment and fundus images was taken considering stable head position in 19 pairs of photographs of eyes with implanted tIOLs. The angle between reference fundus axis and tIOL axis was measured at both time stages (mean: after 3 months). The difference of the angle between bifocal-image samples was defined as the real tIOL rotation angle. 3. Ten pairs of anterior segment photographs of eyes with a tIOL were investigated using the Axenfeld loop analysis. In each photograph, the angle between the axis connecting two Axenfeld loops and the tIOL axis was measured. The difference of two angles of two photographs was defined as the rotational tIOL angle. RESULTS: 1. The mean absolute eye's rotation angle was 2.3 +/- 1.7 degrees (range: 0 to 11.5 degrees) in all 550 eyes. Only 9.1 % of the eyes did not rotate. In 57.3 % of the eyes a rotation of less than 3 degrees and in 33.6 % of more than or equal to 3 degrees was detected. The eye's cyclorotation correlated (p < 0.04) with an age older than 39 years and higher astigmatism (> 1.5 D). Because of the significant amount of spontaneous globe rotation we developed the following enhanced methods to minimize measurement errors of tIOL rotation: 2. Bifocal photography: comparing the 19 HRA anterior segment images, the amount of mean tIOL rotation was 5.4 +/- 4.8 degrees (range: 0 - 20.0 degrees). Using the bifocal photography, the mean tIOL rotation was 1.9 +/- 1.3 degrees (range: 0 - 5.0 degrees). The overestimated rotation of the tIOL (only anterior segment tIOL comparison) correlated with higher amounts of the eye's cyclorotation (r = 0.94; p = 0.01) and higher corneal astigmatism (r = 0.54; p = 0.05). 3. The simultaneous analysis of Axenfeld loops revealed significantly smaller amounts of tIOL rotation (2.3 +/- 2.5 degrees range: 0 - 7.0 degrees ) in 10 pairs of anterior segment photographs in contrast to the single analysis of tIOL axis (5.5 +/- 4.8 degrees range: 1 - 13.0 degrees p = 0.09). A reduction of up to 18.0 degrees tIOL rotation measurement failure was possible in single cases by applying the bifocal photography or simultaneous Axenfeld loop analysis. CONCLUSIONS: Head inclination, head rotation, and incyclo- or excyclorotation of the eye may have a significant impact on the tIOL axis evaluation. Besides the bifocal photography the simultaneous Axenfeld loop analysis could be a promising alternative to the conventional axis evaluation of tIOLs.

Artifacts↗

PubMed2006

[Parapapillary autofluorescence as indicator for glaucoma].

BACKGROUND: A pronounced fundus autofluorescence (lipofuscin) occurs in eyes with AMD. Parapapillary lipofuscin accumulation in the retinal pigment epithelial cells was observed in eyes with advanced glaucoma histologically. The aim of this study was to evaluate the parapapillary autofluorescence (PAF) in vivo in healthy eyes (controls), and in eyes with primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PSXG) or normal tension glaucoma (NTG). PATIENTS AND METHODS: Controlled cross-sectional analysis was performed on 281 consecutive eyes (98 controls, 95 POAG, 32 PSXG, 56 NTG). Eyes with fundus pathologies were excluded. The confocal scanning laser ophthalmoscope HRA II (Heidelberg Retina Angiograph II) was used after lipofuscin-excitation with an argon blue laser (488 nm) to detect PAF in the spectrum above 500 nm. PAF area and PAF distance to the optic nerve head were analyzed using the HRA standard software. Two experienced ophthalmologists classified independently the stage of glaucomatous optic nerve head atrophy (GONHA) using 15 degrees fundus photographs. RESULTS: Vital optic nerve heads had smaller PAF areas (stage 0: 0.07 +/- 0.09 mm (2)) in contrast to advanced stages of GONHA (stages 1 to 4: 0.27 +/- 0.46 mm (2); p < 0.001; logistic regression Cox and Snell: r = 0.7; p = 0.015). The PAF distance to the optic nerve head was lower in controls (0.12 +/- 0.08 mm) than in eyes with POAG, PSXG, or NTG (0.25 +/- 0.21 mm, Bonferroni: p < 0,004). The PAF area correlated significantly with the stage of GONHA (stage 1: 0.23 +/- 0.23 mm (2), stage 2: 0.24 +/- 0.19 mm (2), stages 3 and 4: 0.34 +/- 0.73 mm (2), p < 0.01). No significant difference of PAF area was found between the glaucoma types. However, the distance between PAF and optic nerve head was higher in POAG (0.28 +/- 0.26 mm) than in NTG (0.24 +/- 0.07 mm) or in PSXG (0.18 +/- 0.07 mm, Bonferroni: p < 0.03). CONCLUSIONS: A pronounced fundus autofluorescence was detected as a sign of increased lipofuscin accumulation in the parapapillary atrophic zone of eyes with POAG, PSXG, and NTG in contrast to controls. The PAF analysis may provide an indicator for glaucomas in the future.

Biomarkers↗

PubMed2006

[Reproducibility of dynamic contour tonometry. Comparison with TonoPenXL and Goldmann applanation tonometry - a clinical study on 323 normal eyes].

BACKGROUND: The PASCAL Dynamic Contour Tonometer (DCT) is a new diagnostic approach for the digital measurement of intraocular pressure (IOP) in eyes with glaucoma. The aim of this study was to evaluate the reproducibility of DCT in normal eyes and to compare DCT with Goldmann applanation tonometry (GAT) and TonoPenXL. PATIENTS AND METHODS: A prospective cross-sectional study on 323 normal, consecutive eyes was performed. Eyes with an IOP of more than 23 mmHg (GAT) were excluded. Central corneal power (Zeiss Ophthalmometer) and central corneal thickness (ultrasound pachymetry: Tomey AL-1000) were taken. The IOP readings were obtained as follows: 3 x DCT [quality of measurement, IOP and ocular pulse amplitude (OPA) were taken], 1 x TonoPenXL, GAT, finally: once again DCT to evaluate the tonography effect. RESULTS: The quality of 3 following IOP (DCT) readings was good (quality Q1 = 43.4 %, Q2 = 32.5 %, Q3 = 22.7 %). The reproducibility of the IOP (DCT) measurements was excellent (first measurement IOP (DCT) = 18.1 +/- 3.4 mmHg, second measurement IOP (DCT) = 18.1 +/- 3.4 mmHg, third measurement IOP (DCT) = 17.8 +/- 3.4 mmHg, Cronbach's alpha = 0.976). First and second IOP (DCT) values showed a strong correlation (r = 0.93). A significant tonography effect was observed between first and third IOP (DCT) measurements (0.4 mmHg; p = 0.004). Mean OPA (DCT) was 3.0 mmHg during the first three measurements (Cronbach's alpha = 0.964). IOP (DCT) and OPA (DCT) reproducibility showed no laterality. IOP (DCT) (17.7 +/- 3.4 mmHg) was significantly higher than IOP (TonoPenXL) (16.0 +/- 3.2 mmHg, n = 275; p < 0.001) and higher than IOP (GAT) (14.5 +/- 3.1 mmHg, n = 275; p < 0.001). The effect of tonography between the third and last IOP (DCT) measurement was zero (p = 0.6). IOP (DCT) and IOP (GAT) values were only weak correlated with central corneal thickness. CONCLUSIONS: IOP and OPA values measured with the DCT are extraordinary reproducible in normal eyes. Frequently, DCT detects higher IOP values than those obtained with TonoPenXL and GAT. A reproducible measurement of IOP and OPA may open new diagnostic fields, e. g., in glaucoma detection or ocular vascular diseases.

Cross-Over Studies↗

PubMed2005

[Toric intraocular lenses for correction of persistent corneal astigmatism after penetrating keratoplasty].

PURPOSE: Cataract extraction with implantation of toric intraocular lenses (tIOL) is a new surgical option for correction of residual astigmatism following penetrating keratoplasty and cataract with only minimal direct manipulation of the graft. PATIENTS AND METHODS: We implanted an individually manufactured backtoric tIOL in 11 eyes of 9 patients. TIOL power calculation was done using vergence transformation in a paraxial space. RESULTS: Implantation and intraoperative alignment of tIOL were uneventful in all patients. Uncorrected visual acuity increased from 0.1+/-0.06 preoperatively to 0.47+/-0.18 (p=0.006) postoperatively. Best-corrected visual acuity changed from 0.23+/-0.18 preoperatively to 0.6+/-0.14 postoperatively (p=0.002). The refractive cylinder could be reduced from 7.0+/-2.6 D to 1.63+/-1.5 D (p=0.001) after surgery. We observed a small mean deviation from the target axis of 4.1+/-2.9 degrees (0-8 degrees ) after a mean follow-up time of 3.5 (2-7) months. CONCLUSION: TIOL implantation is a promising option for correction of high astigmatism following penetrating keratoplasty with only minimal direct surgical manipulation of the graft. Regular and symmetric corneal topography is essential for successful implantation of tIOL.

Aged↗

PubMed2005

[The penetrating keratoplasty. A 100-year success story].

Ten precautions for prophylaxis of astigmatism in penetrating keratoplasty are recommended:1. The attempt should be made to determine donor topography for exclusion of previous refractive surgery, keratoconus/high astigmatism, and to allow for "harmonization" of donor and recipient topography.2. Donor and recipient trephination should be performed from the epithelial side with the same system, which is the prerequisite for congruent cut surfaces and angles in donor and recipient. For this purpose an artificial anterior chamber is used for donor trephination.3. Orientation structures in donor and host facilitate the correct placement of the first four or eight cardinal sutures to avoid horizontal torsion.4.A measurable improvement seems to be possible, using the Krumeich guided trephine system (GTS), the second generation Hanna trephine, and the Erlangen technique of nonmechanical trephination with the excimer laser.5. Horizontal positioning of the head and limbal plane are indispensable for state-of-the-art PKP surgery in order to avoid decentration, vertical tilt, and horizontal torsion.6. Graft size should be adjusted individually ("as large as possible, as small as necessary").7. Limbal centration should be preferred over pupil centration (especially in keratoconus).8. Excessive graft over- or undersize should be avoided to prevent stretching or compression of peripheral donor tissue.9. As long as Bowman's layer is intact a double running cross-stitch suture (according to Hoffmann) is preferred since it results in higher topographic regularity, earlier visual rehabilitation, and less suture loosening requiring only rarely suture replacement.10.Intraoperative keratoscopy should be applied after removal of lid specula and fixation sutures.

Astigmatism↗

PubMed2004

Accommodation after Nd: YAG capsulotomy in patients with accommodative posterior chamber lens 1CU.

PURPOSE: After initial encouraging results with the accommodative 1CU posterior chamber lens (PCIOL), we investigated the rate, the postoperative time point of posterior capsular opacification (PCO) necessitating YAG capsulotomy and the accommodative range after Nd: YAG capsulotomy in patients with 1CU-PCIOL. PATIENTS AND METHODS: This prospective clinical study included 65 patients who underwent phacoemulsification and implantation of the accommodative 1CU-PCIOL with postoperative follow-up from 3 to 24 months. Postoperative examination was performed 3, 6 and 12 months after surgery, then before and 6 weeks after Nd: YAG capsulotomy. Measurements included: the best corrected distance visual acuity, distance refraction, near visual acuity (Birkhauser charts in 35 cm) obtained with best distance correction, accommodative range measured by subjective near point with an accodommometer and defocusing with a visual acuity fall to 0.4. RESULTS: Both best corrected distance visual acuity (1.1+/-0.1) and near visual acuity with best distance correction (0.4+/-0.1) remained stable over the follow-up period until 12 months postoperatively. The accommodative range determined by near point was stable (mean 2.0+/-0.5 D). Also, the defocusing range remained stable over 12 months (1.8+/-0.4 D). A clinically relevant posterior capsule opacification with a significant decrease of visual acuity (0.4+/-0.2) and a need for Nd: YAG capsulotomy was diagnosed in 12 patients between 15 and 22 (mean 20+/-4, median 20) months postoperatively. All capsulotomies were performed without complication. Six weeks after capsulotomy, best corrected distance visual acuity was improved (1.1+/-0.1), near visual acuity with best distance correction was 0.4+/-0.1 and the accommodative range determined by near point was 1.95+/-0.6 D and by defocusing was 1.88+/-0.47 D. Six weeks after capsulotomy, measurements of the accommodative range did not show any statistical difference to the 12-month results before the occurrence of PCO (P>0.5). CONCLUSIONS: A clinically relevant PCO with a significant decrease of visual acuity necessitating Nd: YAG capsulotomy occurred mainly after 15 postoperative months in patients with 1CU. Our results indicate that Nd: YAG capsulotomy may not affect the accommodation ability of the 1CU. Nevertheless, long-term studies are needed to further analyze the accommodative properties.

Accommodation, Ocular↗

PubMed2004

[Phototherapeutic keratectomy (o-PTK) with 193 nm excimer laser for superficial corneal scars. Prospective long-term results of 31 consecutive operations].

PURPOSE: To investigate the functional and morphological long-term outcome of phototherapeutic keratectomy (PTK) for superficial corneal scars of varying origin. PATIENTS AND METHODS: Between 1989 and 11/2002, 317 PTKs were performed in Erlangen, of which 31 consecutive procedures were assessed in this prospective study. The intended laser ablation depth after epithelial debridement and pannectomy varied from 12 to 150 microm. We used the slit-scanning-mode (Carl Zeiss Meditec AG) with a repetition rate of 20/s or 25/s, a pulse energy of 14.5 mJ (median) and a pulse rate of 2565+/-2036 (222-6962). In most cases a 6.0 mm metal mask was used to protect peripheral Bowman's layer. RESULTS: After a mean follow-up of 2.0+/-1.9 (maximum 6.9) years, best-corrected visual acuity increased from preoperatively 0.3+/-0.2 to 0.5+/-0.3 (increase 87%, no change 10%, decrease 3%). Corneal surface topography regularized significantly (p=0.02). The spherical equivalent increased only slightly from -0.4+/-2.5 D preoperatively to 0.2+/-2.9 D postoperatively. Likewise, mean keratometric central power did not change significantly. In 10 eyes the maximum postoperative haze was mild, in 4 eyes moderate, and there was only one recurrent scar after delayed epithelial healing following epidemic keratoconjunctivitis. CONCLUSIONS: In superficial corneal scars of varying origin an o-PTK using the 193 nm excimer laser can moderately increase visual acuity in most cases. Therefore, a lamellar or penetrating keratoplasty might be avoided.

Adult↗

PubMed2004

[Results of the first 1,000 consecutive elective nonmechanical keratoplasties using the excimer laser. A prospective study over more than 12 years].

BACKGROUND AND PURPOSE: The purpose of this prospective clinical cross-sectional study was to analyse indications, intraoperative, perioperative and postoperative pecularities and complications as well as postoperative functional and morphologic results of the first 1000 consecutive elective round laser keratoplasties. PATIENTS AND METHODS: The age of the 480 females and 520 males (362 x keratoconus), who had been operated on between 07/1989 and 04/2002 ranged from 20 to 92 years (mean 55+/-19). A total of 6 microsurgeons performed 718 x PK only, 222 x a triple procedure and 60 x additional IOL manoeuvres. Recipient and donor trephinations were accomplished with an 193 nm excimer laser (Carl Zeiss Meditec, Jena, Germany) from the epithelial side. RESULTS: In 895 eyes with perioperative corneal erosion, epithelial healing took not more than 3 days in half of cases. During a follow-up period of 1.9+/-1.5 years, in 35 eyes episodes of acute diffuse (8 irreversible) and in 12 eyes episodes of chronic focal (5 irreversible) endothelial immunologic graft reactions (4.7%) occurred between 6 weeks and 4.7 years after PK. Before/after suture removal, median values of astigmatism were 1.5 diopters (D)/2.5 D refractive, 3.0 D/3.3 D keratometric, and 4.0 D/4.2 D topographic. Best-corrected visual acuity was 0.50/0.60, respectively. CONCLUSIONS: More than 12 years of experience with this new technique indicate that besides optical advantages, nonmechanical trephination does not cause intraoperative or postoperative disadvantages for the patient. Under standardised surgical conditions a massive increase of astigmatism after suture removal seems to be avoidable with laser trephination in most cases due to reduction of decentration,"vertical tilt" and especially "horizontal torsion".

Adult↗

PubMed2004

[Digital planimetry for long-term follow-up of glaucomatous optic disk injuries in patients with normal pressure glaucoma].

BACKGROUND: Aim of the study was to evaluate the validity of quantitative planimetry of the optic disc with a new digital method and to assess the correlation of the measurements with morphological changes in eyes with low tension glaucoma. MATERIAL AND METHODS: The study included 40 eyes from 40 patients (age 61+/-12 years) with low tension glaucoma with a mean follow-up of 4.9+/-2.1 (range 3-9) years. All patients underwent annually complete ophthalmological examination including 15 degrees color optic disc photographs and automated white-white visual fields. RESULTS: Out of 40 eyes morphological examination showed signs of progression in 18 eyes and in 22 eyes no morphological changes of the optic disc were detected The digital planimetrically measured optic disc area did not vary between the first and the last photos. The mean differences between measured values for optic disc area between two examinations were 0.027+/-0.071 mm(2) and the reliability coefficient (Cronbachs alpha) was 0.99. Neuroretinal rim area decreased statistically highly significantly in eyes with morphological progression, and in eyes without morphological changes decreased only slightly. CONCLUSIONS: The variation of measurements of the optic disc area can be minimized by consideration and adjustment of the individual image magnification of the photos using digital planimetry. This method allows the quantitative assessment even of slight changes of the neuroretinal rim area and is a useful examination for follow-up of glaucoma patients.

Disease Progression↗

PubMed2004

[Rotational stability of the eye in standard photography].

BACKGROUND: After the implantation of a toric IOL (tIOL), postoperative rotations of more than 30 degrees have been reported. Beyond this scope, we investigated the reproducibility of the eye's orientation (rotation stability) in principle. PATIENTS AND METHODS: The rotational stability of the eye was investigated using standard fundus photographs (telecentric fundus camera, Zeiss, Oberkochen). One hundred eyes of 50 patients (28 females) were photographed in a time interval of more than 6 months twice. With the aid of significant markers on the fundus photograph, the axial position of the eye was defined and the rotational angle between the two slides of one eye was measured. RESULTS: The mean absolute rotational angle was 2.4 +/- 1.7 degrees (range 0 to 7.5 degrees ) in all 100 eyes (2.5 +/- 1.6 degrees right eye, 2.4 +/- 1.7 degrees left eye). Only 6 % of the eyes did not rotate. A range of less than 3 degrees rotation was detected in 52 % of the eyes. A rotation of equal to or more than 3 degrees was noted in 42 %. The patient's age did not influence the amount of globe rotation. In- and excyclorotations showed a coincidental distribution and no side differences. CONCLUSIONS: Seven and a half degrees or 3 degrees tIOL rotation would correspond to a residual astigmatism of 26 % or 10 %. When measuring the marked axis of the tIOL, these results are markedly influenced by head inclination, rotation of the head, incyclorotation or excyclorotation. This is transferable, for example, to autorefractor, corneal topography and sectorial analyses for glaucoma diagnostics.

Eye Movements↗

PubMed2004

[Toric intraocular lenses for compensation of corneal astigmatism].

BACKGROUND: Besides arcuate or straight transverse keratotomies, toric intraocular lenses are of increasing popularity to enhance the visual function in cases of lens opacification for the correction of corneal astigmatism and the following ocular surgery such as penetrating keratoplasty. The purpose of this study was to present a generalized scheme for the calculation of toric intraocular lenses and to demonstrate its potential on a clinical example in a step-by-step approach. METHODS: After providing some helpful approximations for the clinicians, i. e., for a conversion of radii differences to corneal astigmatism, the calculation scheme using vergence transformation in a paraxial space and the dualism of the standard and component notation for the description of spherocylindrical vergences and spherocylindrical refractive surfaces is described. RESULTS: In a clinical example, a toric intraocular lens is calculated step-by-step using the above-mentioned calculation scheme. The methodology is designed in a matrix structure for the direct implementation in a computer language. In a second step, a toric lens similar to the calculated lens in the manufacturing grid is selected and inserted with a small angle of rotation from the ideal implantation axis to demonstrate the effect on postoperative refraction. CONCLUSIONS: The calculation scheme allows the determination of toric intraocular lenses with an astigmatic cornea and enables us to achieve a spherocylindrical target refraction with cylinder axis at random. Furthermore, the postoperative refraction at the spectacle or corneal plane can be simulated by inserting any toric intraocular lens oriented in any axis. The concept can be easily generalized to 'thick' toric intraocular lenses if the geometrical data and the refraction index of the material are known.

Astigmatism↗

PubMed2004

[Bilateral visual field defects with optic disc drusen and secondary open angle glaucoma with PEX--clinical correlation with the HRA].

BACKGROUND: Arcuate visual field defects are a typical sign of glaucomatous damage. Elevated intraocular pressure in combination with pseudoexfoliation syndrome (PSX) manifests the diagnosis glaucoma. Beyond this state, in microdiscs with optic disc drusen, the exact classification of the visual field defects is crucial. CASE REPORT: A 57-year-old male with pseudoexfoliation glaucoma was referred because of progressive glaucomatous visual field defects. The visual acuity was right 20/40 and left 20/25. Maximum intraocular pressure was 36 mm Hg. A simple optic nerve atrophy was diagnosed superonasally. The optic disc size was OD 2.24 mm(2) and OS 1.89 mm(2) (HRT I). An Ultrasound B-mode scan demonstrated the diagnosis of optic disc drusen. Over a follow-up of 1 year, a growth tendency was observed, especially in the superonasal quadrant. The mulberry-shaped surface of the drusen was visualized with infrared reflection images (HRA II, 830 nm). Confocal scanning laser ophthalmoscopy (HRA II, excitation 488 nm, 500 nm notch filter) showed an increased intrapapapillary autofluorescence (> 50 % papillary area: OD 1.67 mm(2), OS 1.26 mm(2)). This technique could detect drusen in areas that looked normal in classical retinoscopy. CONCLUSION: The differential diagnosis of arcuate scotomas includes simple optic nerve atrophy and glaucomatous optic nerve atrophy. Optic disc drusen in glaucoma eyes can obscure the main cause of progressive visual field loss. Superficial optic disc drusen can be measured planimetrically over the years. An adequate reduction of intraocular pressure should be realized in these eyes.

Diagnosis, Differential↗

PubMed2004

[Clinical aspects and treatment of immune reactions following penetrating normal-risk keratoplasty].

PURPOSE: Endothelial graft rejection is one of the most common causes of graft failure following penetrating keratoplasty (PK). The aim of this study was to evaluate the incidence, time course and outcome of treatment of graft rejection after normal-risk PK and to identify possible risk factors for the recurrence of immune reactions and irreversible graft failure. PATIENTS AND METHODS: The study included 500 eyes from the prospective Erlanger Normal-risk Keratoplasty Study with a mean follow-up of 42 +/- 18 (median 40) months. Indications for PK were keratoconus in 48 %, Fuchs' dystrophy in 30 %, secondary bullous keratopathy in 11 %, non-vascularized corneal scars in 7 % and stromal dystrophies in 4 %. Standardized complete ophthalmological examinations were performed on a regular basis before, during the acute graft rejection and then regularly in a defined examination raster in an cornea out-patient service. RESULTS: During follow-up 29 eyes (5.6 %) developed an episode of endothelial graft rejection (23 eyes with acute diffuse and 6 eyes with chronic focal rejection type). Episodes of endothelial graft rejection clustered between 11 and 25 months postoperatively (15 from 29, 51.7 %). Most grafts (25 of 29) regained clarity after topical and systemic steroid treatment. Only 4 patients showed an irreversible graft failure requiring a repeat PK, all of whom had secondary bullous keratopathy as the primary indication for PK. Risk factors for irreversible graft failure were pre-existing anterior synechiae in 3 patients and secondary open angle glaucoma in pseudoexfoliation syndrome in one patient. Recurrence of graft rejection was seen in 5 patients (all with keratoconus) after a time interval of 8 to 12 months. Under very low topical steroid treatment no further recurrence was observed in all 5 patients up to 2 years. CONCLUSION: Patients should be followed-up on a regular base for longer postoperative periods, since most episodes of graft rejection were observed between 1 and 2 years after PK. Development of irreversible graft failure was strongly associated with pre-existing anterior synechiae and pre-existing glaucoma. Low-dose topical steroid treatment after immunological rejection seems to prevent the recurrence of further graft rejection.

Adult↗

PubMed2004

[Bifocal photography using the HRA -- an optimized method to evaluate tIOL's axial orientation].

BACKGROUND: The assessment of axial orientation of toric IOLs (tIOLs) by monofocal photography can be deteriorated due to intrinsic errors e. g. globe rotation, head inclination or inadequate camera adaption and slide projection. METHOD: In a 67 years old female a tIOL was implanted after penetrating keratoplasty for correction of high corneal astigmatism. A sequence of two fundus and two tIOL photographs (bifocal photography) was taken in a time interval of 3 months using the HRA II (Heidelberg Retina Angiograph II). A reference at the fundus was defined using two characteristic markers. The axial fundus orientation between the markers was overlaid to the line defined by the tIOL axis markers. The angular offset/distance between the fundus orientation line and the tIOL marker line was analyzed for each bifocal image at different time points. RESULTS: The comparison of axial tIOL orientation between both different tIOL images revealed a rotation angle of 13 degrees (monofocal photograph). In contrast, using the bifocal photography and digital overlay technique the fundus line as a reference the tIOL rotated 1 degrees and 4 degrees from the first to the second time point of photography. Thus, the real rotation angle of tIOL measured only 3 degrees. CONCLUSION: The bifocal photography with constant head position has the potential to minimize the intrinsic error in documentation of axial orientation of tIOL.

Aged↗

PubMed2004

[Impact of prostaglandin-F(2alpha)-analogues and carbonic anhydrase inhibitors on central corneal thickness -- a cross-sectional study on 403 eyes].

BACKGROUND: Histological changes of, in particular, collagen and extracellular matrix after administration of topical prostaglandin F(2alpha)(PGF (2alpha)) analogues have been reported. In view of this observation, we investigated the influence of PGF(2alpha) analogues on the central corneal thickness. PATIENTS AND METHODS: In a non-randomized, controlled, cross-sectional study, 403 eyes from 208 consecutive patients were examined: 149 eyes (normals/controls) and 79 with ocular hypertension (OHT), 119 eyes with primary open angle glaucoma (POAG) and 56 eyes with normal tension glaucoma (NTG). One experienced ophthalmologist measured the central corneal thickness (CCT) using ultrasound pachymetry (Tomey AL-2000, sequence of 5 measurements with an SD < 3 microm). The central corneal power was measured with the Zeiss keratometer. Depending on the topical treatment, the patients were classified into 4 groups: A) PGF(2alpha) analogues (n = 78), B) carbonic anhydrase inhibitors (n = 26), C) combination of PGF (2)(alpha) analogues and carbonic anhydrase inhibitors (n = 41), D) none of these drugs (n = 258). T tests and multiple linear regression analyses were used for statistical analysis. RESULTS: CCT was decreased significantly (p < 0.01 each) in eyes treated with PGF(2alpha) analogues (group A: 529 +/- 34 microM), in comparison with the untreated and non-glaucomatous eyes (part of group D: 542 +/- 35 microM, n = 148), untreated glaucomatous/OHT eyes (part of group D: 563 +/- 37 microM, n = 110), eyes treated with carbonic anhydrase inhibitors (group B: 561 +/- 32 microm) and eyes with a topical application of both PGF (2)(alpha) analogues and carbonic anhydrase inhibitors (group C: 555 +/- 48 microM. No correlation was found between CCT and diagnosis (OHT, POAG, NTG, control), gender, central corneal power, and intraocular pressure in a multivariate analysis. CONCLUSIONS: The present findings suggest that the topical application of prostaglandin F(2alpha) analogues onto the cornea reduces the central corneal thickness significantly. These changes might be attributed to effects of PGF(2alpha) analogues on the extracellular matrix of the corneal stroma via upregulation of matrix metalloproteinases. In clinical practice, corneal thinning under local PGF (2)(alpha) analogue treatment could result in underestimation of intraocular pressure levels as measured by applanation tonometry.

Acetazolamide↗

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↗