Arne Viestenz

Anterior chamber depth and complications during cataract surgery in eyes with pseudoexfoliation syndrome

PURPOSE To look for associations of preoperative A-scan ultrasound ocular dimensions with complications during phacoemulsification in eyes with pseudoexfoliation. METHODS A total of 174 eyes with pseudoexfoliation of 135 patients undergoing planned cataract surgery were included in a prognostic study based on the review of a clinical database. Preoperatively, A-scan ultrasound examination with measurement of anterior chamber depth, lens thickness, and total axial length was performed. Phacoemulsification with implantation of a posterior chamber intraocular lens was performed by a total of five surgeons. Intraoperative complications (zonular dialysis and/or vitreous loss) were correlated with preoperative findings including ultrasound dimensions. Multivariate logistic regression analysis with a generalized estimating equations method was used for statistical analysis. RESULTS Intraoperative complications occurred in 12 eyes (6.9%) of 11 patients. The anterior chamber was significantly shallower in eyes with than in eyes without complications (mean, 2.36 +/- 0.44 mm vs 2.74 +/- 0.52 mm; P =.013). The differences in lens thickness (4.93 +/- 0.55 mm vs 4.72 +/- 0.54 mm; P =.30) and the differences in axial length (22.92 +/- 1.09 mm vs 23.66 +/- 1.36 mm; P =.07) between the two groups did not reach statistical significance. In eyes with pseudoexfoliation, an anterior chamber depth of less than 2.5 mm was associated with a risk of 13.4% for intraoperative complications compared with an overall incidence of intraoperative complications of 6.9% and an incidence of 2.8% for an anterior chamber depth of 2.5 mm or more. CONCLUSIONS A small anterior chamber depth may indicate zonular instability in eyes with pseudoexfoliation syndrome and should alert the cataract surgeon to the possibility of intraoperative complications.

Evaluating the eye's rotational stability during standard photography: effect on determining the axial orientation of toric intraocular lenses.

Purpose: To evaluate the rotational stability of the eye during standard photography and determine its effect on the measurement of toric intraocular lens (IOL) orientation. Setting: Department of Ophthalmology, University Erlangen‐Nuremberg, Erlangen, Germany. Methods: The rotational stability of the eye was evaluated using standard photographs taken with a telecentric fundus camera (Zeiss). Two sets of fundus images were taken at least 6 months apart in 400 eyes of 200 patients. The axial position of the eye was determined using 2 characteristic markers of the fundus. The angle between the 2 images (autorotation angle) was measured in each eye. Results: The mean absolute autorotation was 2.3 degrees ± 1.7 (SD) (range 0 to 11.5 degrees). Nine percent of eyes did not rotate. The rotation was less than 3 degrees in 55% of eyes and was 3 degrees or greater in 36% of eyes. Eyes of patients younger than 50 years rotated less than eyes in older patients (mean 2.2 ± 1.5 degrees and 2.5 ± 1.8 degrees, respectively) (P = .04). A visual acuity of 20/20 or better (P = .02) and a refractive cylinder of less than 1.75 diopters (P = .01) were correlated with smaller amounts of autorotation. Potential causes of artificial eye rotation induced by the photographic technique included camera adaptation (3‐degree intrinsic error), slide mounting (<1 degree), slide projection (<0.5 degree), marking of characteristic fundus details (<1 degree), and head inclination. Conclusions: Cyclorotation of the eye during standard photography may lead to overestimation or underestimation of the presumed spontaneous rotation of an implanted toric IOL. Results show that 11.5 degrees of toric IOL rotation would lead to residual astigmatism that is 40% of the initial astigmatic power and 3 degrees, 10% of the initial power. Digital imaging may reduce the intrinsic errors of standard photography.

Biomechanical profile of the cornea in primary congenital glaucoma

Purpose:  The aim of our study was to investigate the biomechanical properties of the cornea in primary congenital glaucoma (PCG) and to identify the potential ocular determinants, which affect the corneal biomechanical metrics.

Histopathology of corneal changes in lecithin-cholesterol acyltransferase deficiency.

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

Quantification of neuroretinal rim loss using digital planimetry in long-term follow-up of normals and patients with ocular hypertension.

PurposeThe purpose of this study was to investigate if digital planimetry is appropriate for quantification of neuroretinal rim loss in patients with ocular hypertension (OHT) and if there is an age-related neuroretinal rim loss in normals. Patients and MethodsFifty-six patients with OHT without optic disc change, 13 patients with OHT and conversion to early glaucoma during follow-up and 42 age-matched controls were recruited from the Erlangen Glaucoma Registry. Annually, all patients underwent complete ophthalmologic examination including detailed diagnostic testing concerning glaucoma. Gold standard for morphologic evaluation of the optic nerve head was the semiquantitative 2-dimensional-method described by Jonas. Optic disc images from baseline and after 5 or 10 years follow-up were used for digital planimetry. Optic disc area and cup area were measured using commercial software: Soft Imaging System analysis. The investigator was masked for diagnosis and time point of examination. ResultsMean neuroretinal rim loss was 0.36% per year in controls, 0.54% per year in patients with OHT without progressive disease, and 0.95% per year in OHT and conversion. ConclusionsNeuroretinal rim loss was highest in the group of OHT with conversion to early glaucoma during follow-up. In the control group we detected a very low mean neuroretinal rim loss during 10-year follow-up. In ocular hypertensive patients without progressive disease mean neuroretinal rim loss was approximately twice compared with normals.

Ocular contusion caused by elastic cords: a retrospective analysis using the Erlangen Ocular Contusion Registry

Purpose: Elastic cords are common tools to secure luggage to the roof of motor vehicles or the carrier of bicycles. In comparison with other variants of ocular contusion, patients with elastic cord injuries appear to suffer more severe ocular damage.

Ray tracing through a schematic eye containing second‐order (quadric) surfaces using 4 × 4 matrix notation

Ray tracing is used in ophthalmology for evaluation of the optical properties of the eye. We demonstrate an algebraic method for tracing a bundle of rays through the optical system of an eye containing aspheric surfaces. Restricting to second‐order surfaces (quadric surfaces) such as ellipsoids, paraboloids or hyperboloids, a surface is described by a 4 × 4 matrix. In this case, the normal vector can be derived analytically and the ray‐surface intersection is calculated by solving a quadratic equation. We applied this straightforward matrix‐based strategy to the spherical 4‐surface Le Grand schematic eye, and the Le Grand eye modified by Kooijman containing four aspheric surfaces. We calculated the spot diagram for the focal plane as well as a pre‐ and post‐focal plane for both model eyes, and found that the optical quality of the aspheric model characterized by the ray scatter in the spot diagram at the focal plane is much better than that of the spherical model. This calculation strategy may be helpful for evaluating the image distortion of decentred or tilted spherical or aspheric artificial intra‐ocular lenses.

Association between localized visual field losses and thickness deviation of the nerve fiber layer in glaucoma.

Purpose:To perform a correlation between morphology and function by studying local perimetric field losses and thickness reduction of the nerve layer in corresponding areas. Method:Forty-seven patients with “preperimetric” open-angle glaucoma, 95 patients with “perimetric” open-angle glaucoma, and 75 control subjects had perimetric (Octopus) and polarimetric measurements. Criteria for exclusion: optic discs larger than 4 mm2, media opacities, polarimetric hourglass pattern in the macular image. Thickness values of the retinal nerve fiber layer were determined in 14 upper and 14 lower sectors (10° each) as well as nasally and temporally (40° each) as provided from the GDx (software version 4000). The healthy control subjects served to determine age-corrected thickness deviation in all sectors. Analyses were calculated in eight nerve fiber bundle related areas. Due to non-linear relationships between perimetric defects and corresponding thickness deviation non-parametric tests were used. Results:Localized visual field defects in the present perimetric patients were highest in upper and lower visual field areas abutting the nasal meridian. Thickness loss of nerve fiber layer however was highest in more circumferential upper and lower nerve fiber bundles. Correlations between local mean defects and deviation of the retinal nerve fiber layer thickness from normals showed a clear association for corresponding areas. The correlation coefficients were significant (P < 0.01) for all arcuate superior and inferior visual field zones except horizontally and not for the area of the lower nasal step. Conclusion:The present correspondence map indicates that focal perimetric defects can be identified best polarimetrically if they occur in the arcuate bundles of the visual field. A lack of correspondence was observed in the area of the papillo-macular bundle.

Vigabatrin-assoziierte bilaterale einfache Optikusatrophie mit konzentrischer Gesichtsfeldeinengung

ZusammenfassungKasuistik. Ein 70-jähriger, vormals mit Vigabatrin behandelter Patient stellte sich mit blassen Papillen und einer bilateralen konzentrischen Gesichtsfeldeinengung auf 35° vor.Die kumulative Dosis betrug 3,7 kg. Die B-Welle war im photopischen und skotopischen ERG reduziert, die Latenzzeit im VEP war verlängert.Im HRT und GDx war die Dicke der retinalen Nervenfaserschicht pathologisch reduziert. Schlussfolgerung. Vigabatrin kann als Antikonvulsivum durch eine Hemmung der GABA-Transaminase die retinale GABA-Konzentration erhöhen und zu einer aufsteigenden einfachen Optikusatrophie führen.Vigabatrin-assoziierte Gesichtsfeldausfälle können irreversibel sein.Vor Beginn der Therapie und in 6-monatigem Intervall werden Gesichtsfeldkontrollen empfohlen.Bei Konstriktion sollte Vigabatrin abgesetzt werden.Aufgrund der Dosis-Toxizitäts-Abhängigkeit sollte ab einer kumulativen Dosis über 3 kg engmaschig kontrolliert werden.AbstractCase report. A 70-year-old male with optic disc pallor and visual field constriction up to 35° bilaterally was previously treated with vigabatrin.The cumulative dosage was 3.7 kg. The b-wave was reduced in photopic and scotopic electroretinography and the patient had delayed visual evoked potentials.The retinal nerve fiber thickness was pathologically reduced in the Heidelberg retinal tomography (HRT) and the retinal nerve fiber layer analyzer (GDx). Conclusion. Vigabatrin is an antiepileptic drug and may increase the intraretinal GABA level due to an inhibition of the enzyme GABA-transaminase and may induce an ascending simple optic nerve atrophy.Vigabatrin-associated visual field defects may be irreversible. A visual field control is recommended before starting the treatment with vigabatrin and at regular 6-month intervals thereafter. In cases of visual field constriction, the therapy should be stopped. If the cumulative dosage is more than 3 kg of vigabatrin, the visual field controls should be performed more frequently because of the dosage-toxicity relationship.

Evaluation of corneal flap dimensions and cut quality using the SKBM automated microkeratome

Purpose: To evaluate flap dimensions and cut quality with repeated blade use of the automated Summit Krumeich‐Barraquer microkeratome (SKBM® [LadarVision]). Setting: Department of Ophthalmology, University Erlangen‐Nuremberg, Erlangen, Germany. Methods: The SKBM (160 &mgr;m plate, intended flap diameter 9.0 mm) was used to perform a corneal hinged flap in 35 pig cadaver eyes. Seven blades were reused 5 times each. The flap diameter was measured by planimetry, and the thickness was assessed by ultrasonic pachymetry. Scanning electron microscopy (SEM) of blades and stromal beds was performed. Results: With single use of the blade, the mean central flap thickness was 145 &mgr;m ± 25 (SD). The vertical/horizontal flap diameter was 9.0 ± 0.03 mm/8.6 ± 0.03 mm. No thickness gradient was observed from the incision (138 ± 31 &mgr;m) to the flap hinge (130 ± 30 &mgr;m). If the blade was used more than 2 times, the flap was thinner at the incision (157 ± 34 &mgr;m versus 124 ± 20 &mgr;m; P = .003) and the hinge (143 ± 24 &mgr;m versus 122 ± 31 &mgr;m; P = .04), but the central thickness remained unchanged. With multiple use of the blade, SEM analysis showed increasing cut irregularity, more tissue remnants on the blade surface, and a progression in blade irregularities (up to 9.3 &mgr;m). Conclusions: Reproducible flap size and thickness can be obtained with single use of stainless steel blades in the SKBM. With multiple use, the quality of the blades and the stromal bed deteriorates and the peripheral thickness of the flaps decreases. Thus, single use of blades is recommended.