AUGENHEILKUNDE 213/1999 – ISSUE 3

Abstracts:

S. 126-131 (Art. 392)

Glaucoma and pregnancy. Literature review with case report
Claus Cursiefen, Anselm Jünemann, Matthias Korth

Background Intraocular pressure usually decreases during pregnancy. Pregnancy-related physiological changes do not seem to cause progression of glaucoma.

Patient and methods The literature regarding glaucoma, ocular hypertension and pregnancy indexed in Medline™ is reviewed. In addition, we report on a 35-year-old patient with ocular hypertension and a known glaucoma family history, who was thoroughly examined before, during and after pregnancy (visual fields, optic disc measurements, 24-hours tension profile, sense physiology ["Erlanger flicker-test", pattern-reversal-ERG, blue-yellow-VEP], ocular perfusion).

Results Visual fields and optic disc measurements did not become worse during pregnancy. Also the other sensory parameters ("Erlanger flicker-test", pattern-reversal-ERG, blue-yellow-VEP) did not deteriorate. Intraocular pressure was reduced by 7 mm Hg during and 2 months after pregnancy. Systolic and diastolic blood velocity of the ophthalmic artery measured by dopplersonography was increased by 60% during pregnancy.

Conclusions According to present knowledge pregnancy is associated with decreased intraocular pressure and does not seem to constitute a risk factor for progression of ocular hypertension or primary open angle glaucoma. Whether antiglaucomatous drug therapy during pregnancy is necessary awaits further evaluation.

Key words Pregnancy - glaucoma- ocular hypertension - glaucoma therapy

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S. 132-140 (Art. 358)

Zernike decomposition of corneal topography data for correction of corneal surface irregularities with the excimer laser
Achim Langenbucher, Berthold Seitz, Murat M Kus, Gerhard J van der Heyd

Background A retinal image performance distorted by an asymmetric or irregular corneal surface cannot be compensated for with spherocylindric glasses completely. The best-corrected visual acuity is markedly decreased and contact lens fitting often impossible. The purpose of this study was to calculate the differential height between corneal topography raw data and any regular surface with mathematical methods in order to to ablate the differential height with a computer-controlled laser beam, thereafter.

Methods A Zernike decomposition of radial degree n=16 was realized within a clinically relevant central corneal area of 8 mm in diameter based on corneal topography raw height data of a commercially available topographer (TMS-1, Tomey, Erlangen). Any target surface could be defined by varying weighting of the Zernike coefficients. The calculated differential height ablation between the raw data and the target surface given in a polar grid was transformed to a Cartesian grid to evaluate the sleeping time at each grid position considering the characteristic ablation curve for the intended ablation of the height difference. Subsequently, differential height ablation was simulated using an automated laser beam control for a modified excimer laser (MEL60, Aesculap-Meditec, Jena). We developed software tools for Zernike decomposition of corneal topography raw height data and time-regulated automatic laser beam control of the grid positions in the higher programming language C (Borland C++ 3.1, Borland Inc., München).

Results Definition of a target surface can be realized alternatively by selecting a set of Zernike coefficients or defining a spherical or spherocylindrical surface by superposition of parabolic terms in a fixed proportion creating a best-fit target surface to the raw data. In orginally "relatively flat" areas, the differential height profile indicates a "relatively deep" ablation resulting in relative steepening towards the periphery of the ablation zone. The resolution of the mechanical unit of the laser beam control consisting of two linear stepping motors is 9 µm in the focal plane with a reproducibility of 5 µm. The software unit is guiding the laser beam in a meandering fashion within the ablation area considering the calculated sleeping time for each grid position. Mean overlap of the 1 mm laser spots is 70%. The laser beam diameter of 1 mm effects a peripheral transition zone of 0.5 mm.

Conclusions Zernike decomposition of corneal topography height data is an efficient tool for localizing and quantifying superficial irregularities and for directly calculating an ablation profile from created differential height data. With an automatical laser beam control a well-defined laser ablation of superficial corneal irregularities is possible, subsequently.

Key words Irregular astigmatism - corneal topography - Zernike decomposition - automatic laser beam control - excimer laser - photorefraktive keratectomy - PRK

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S. 141-146 (Art. 402)

Corneal penetration of different aminoglycosides and chinolones
Kathrin Luthardt, Ria Beck, Eva-Maria Hehl, Günther Kundt, Bernd Drewelow, Rudolf Guthoff

Background Penetration of the aminoglycosides gentamicin and tobramycin and chinolones ciprofloxacin and ofloxacin applied as eyedrops and soaked disposable lenses (ACUVUE), used as antibiotic prophylaxis, was investigated.

Materials and Methods 217 patients received before undergoing cataract extraction 0.3% solutions of these antibiotics as eyedrops or by soaked ACUVUE-lenses. During surgery 50-100 µl aqueous humor was aspirated; concentration of gentamicin and tobramycin was analysed by fluorescence polarisation immuno assay, concentration of ciprofloxacin and ofloxacin was analysed by high pressure liquid chromatography.

Results After application of gentamicin and ofloxacin as eyedrops and via soaked ACUVUE-lenses as drug delivery system (DDS) we found higher concentrations than after application of tobramycin and ciprofloxacin by the same modes. After using of soaked lenses as DDS the aqueous humor concentrations of all tested substances were higher than the concentrations after the frequent instillation of eyedrops.

Conclusions Penetration of gentamicin through normal human cornea is higher than penetration of tobramycin; penetration of ofloxacin through normal human cornea is higher than penetration of ciprofloxacin. The aqueous humor concentrations of ofloxacin applied as eyedrops and DDS, of ciprofloxacin and gentamicin applied as DDS allow their use as antibiotic prophylaxis in cataract sugery.

Key words Aminoglycosides - Fluorochinolones - topical application - corneal penetration-aqueous humor concentration

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S. 147-153 (Art. 394)

Intrastromal corneal ring segments (ICRS™, KeraVision™ Ring)
One year results of the first 25 surgeries
Josef Ruckhofer, Egon Alzner, Günther Grabner

Background The advantages of the Intrastromal Corneal Ring Segments (ICRS™) as compared to the frequently used methods for the correction of low to moderate myopia (RK, PRK, LASIK) are the intact optical zone and nearly complete reversability.

Patients and Methods Two ICR-Segments™, made of PMMA (with an arc length of 150° each) are placed in the deep stromal layers via a small radial incision. At the Landesaugenklinik Salzburg 25 continous surgeries were performed as part of the European "MECCA-trial".

Results Refractive results, intra- and postoperative complications with a follow-up of 12 months are presented. There was no visual loss after one year. In 40% (10/25) the best corrected visual acuity remained unchanged. In 56% (14/25) one line was gained, once two lines were gained. The spherical equivalent was slightly in the range of undercorrection - as wanted. The refractive astigmatism increased (0.5 dpt). The keratoscopy image showed positive aspheric appearence.

Conclusion The ICRS™ (KeraVision™ Ring) seems to offer a precise and stable method to correct low myopia. The procedure is reversible to a large extent, potentially adjustable within certain limits and carries a minimal risk only. Although long-term follow-up is not available yet, initial results of the technique seem very promising.

Key-words Intrastromal Corneal Ring Segments (ICRS™) - myopia - refraction - complications

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S. 154-160 (Art. 399)

Long-term results of optic nerve sheath fenestration in pseudotumor cerebri
Volker Herzau, H Emre Baykal

Background Chronic papilledema may lead to irreversible damage of optic nerve fibers. To preserve visual functions, a decompression of the optic nerve is recommended by means of a fenestration of the optic nerve sheath. In this study long-term results after optic nerve sheath fenestration in patients with idiopathic pseudotumor cerebri are reported.

Patients and methods 14 patients were re-examined 15 to 145 months (mean 62 months) after a fenestration of the retrobulbar optic nerve sheath on 23 eyes by a transconjunctival approach. Surgery was done to treat progressive visual loss or in severe obscurations. The patient's symptoms, visual acuity, visual fields, and ophthalmoscopic findings of the optic nerve head and the central fundus were compared to the preoperative status.

Results Re-examination revealed improvement or stabilisation of objective and subjective findings in 17 eyes, one of them was operated on the more involved contralateral side only. Six eyes showed a recurrence of the papilledema without a functional change for the worse after an interval of 7 to 121 months. Three eyes of two patients ended up with optic atrophy and extensive visual loss. Preoperatively, these eyes had shown cotton wool spots in the optic nerve head and a rapid deterioration of vision.

Conclusions Fenestration of the retrobulbar optic nerve sheath can prevent further visual loss in most patients with pseudotumor cerebri, unless the eye has already become nearly blind. Postoperatively, ophthalmological controls are necessary at regular intervals because relapses after successful surgery can occur after months or years.

Key words Pseudotumor cerebri - papilledema - optic nerve sheath fenestration - long-term results

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S. 161-165 (Art. 388)

IOL calculation and ultrasound biometry: immersion vs. contact technique
Peter C Hoffmann, Werner W Hütz, H Berthold Eckhardt, Alexander H Heuring

Background Ultrasound biometry for axial length measurement may be performed either by directly putting the probe on the cornea or by using a water immersion technique. Our goal was to examine whether there are unsystematic differences between both techniques present besides systematic differences that can be compensated by adjusting calculation formula constants.

Patients, materials and methods We examined 288 patients in a prospective, randomized trial. There was no ocular pathology present beside cataract. Axial lengths < 21 mm and >27 mm were excluded. We calculated which IOL power would have given the desired refractive result by using the postoperative refraction and data of the lens implanted.

Results A systematic difference between both techniques is present. With the contact technique, axial length is measured 0,15 mm shorter. This requires adjustment of formula constants. Furthermore, there is an unsystematic difference that leads to 18% greater calculation errors (difference between IOL calculated preoperatively and ideal IOL) with the contact technique. Mean absolute error was 0.43B0.38 dpt for the immersion group and 0.53B0.48 dpt for the contact group.

Conclusions To minimize postoperative refractive errors, ultrasound biometry using immersion technique should be preferred.

Key words Intraocular lenses - calculation of intraocular lenses - cataract - cataract surgery - computer - biometry - ultrasound

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S. 166-173 (Art. 393)

Screening for amblyopia, strabismus and refractive anomalies in 1030 kindergarten children: results and suggestions concerning the practicability of screening
Barbara Käsmann-Kellner, Manuela Heine, Britta Pfau, Anja Singer, Klaus W. Ruprecht

Background There are controversies concerning the necessity of pre-school vision screening. Aim of the study: evaluation of the prevalence of pathologic ophthalmologic findings in kindergarten children.

Materials and Methods 1030 families were offered a vision screening. Of these, a total of 948 children, aged 3 to 6 years, voluntarily underwent a screening for strabismus, amblyopia and refractive anomalies. The examination was performed in the kindergarten in the absence of the parents.

Methods of examination A questionnaire concerning general and ophthalmologic history of the child and of the family was evaluated. Visual acuity, cover-uncover-test, Lang-stereotest, retinoscopy, ophthalmoscopy (undilated pupils) were performed and the glasses were evaluated.

Results The screening was highly accepted by the parents and 92% of the families (n=948) took part. The compliance of the children was very good. A total of 38.7% (n=381) of the children showed one or more abnormal parameters. 21.4% (n=229) showed a reduced visual acuity. Strabismus was found in 3.7%. Half of the children with abnormal findings already had had a vision screening, but only 25% had received ophthalmologic treatment. Of those who possessed glasses, 25% came without them, and another 25% had a reduced visual acuity even with their glasses. The main problems were many false-positive results and high costs.

Conclusions Ophthalmologic and orthoptic screening in kindergarten is technically easy and conclusive in experienced hands. Ideas to reduce costs and to avoid overreferrals are an age-related lowering of the visual acuity limit and a re-screening of suspected children in a screening-setting a second time before sending them to an ophthalmologist. Another possibility to reduce costs would be to perform examinations not by ophthalmologists but by "screening-orthoptists" who should be trained in retinoscopy and ophthalmoscopy.

Key words Screening - visual acuity - strabismus - amblyopia - refractive error - kindergarten - child - prevention - visual impairment

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S. 174-181 (Art. 401)

A new German Reading Chart* for the simultaneous evaluation of reading acuity and reading speed
Wolfgang Radner, Ulrike Willinger, Wilfried Obermayer, Claudia Mudrich, Michaela Velikay-Parel, Brigitte Eisenwort

Background Reading acuity as well as reading speed are good predictors of everyday visual function. As visual acuity tests are poor predictors of the real-world function, performance-based tests, e.g. reading speed measurements, can be used for the determination of visual function. Thus, a German reading chart was developed in order to evaluate reading acuity as well as reading speed.

Methods Print size is defined as the height of a lower case x and progresses logarithmically from one phrase to another (factor: 1.25). Reading acuity is determined in LogRAD (Reading Acuity Determination). 32 short German phrases were created, comparable concerning grammatical difficulty as well as in number (np14), length and position of words. The reading speed parameters measured with a stop-watch in 160 persons (aged: xp21aB3.8a) were calculated in words per minute (w/min). Out of the 32 phrases the 24 most similar ones were selected statistically and used for the reading charts (Radner Reading Charts). With these reading charts a reading acuity score (LogRAD-score) can be calculated considering reading errors in words of different length. Reading speed can be determined at the same time. Reading acuity (LogRAD-Score) was measured in 32 normal eyes of 16 students and compared to the angular visual acuity (LogMAR).

Results The mean reading speed of the test persons was 211.8B34.1 w/min. 24 phrases fulfilled the test item criteria for the reading chart: mean B0.25!SD. The reliability analyses yielded an overall Cronbach's alpha coefficient of 0.98! The mean visual acuity measured in 32 eyes was P0.115B0.097 LogMAR and the mean reading acuity score was c0.026B0,091 LogRAD. The mean difference was c0.104B0.066 and the correlation between LogMAR and LogRAD was good (rp0.59).

Conclusions With these reading charts it is for the first time possible to simultaneously determine reading acuity as well as reading speed in German. The high reliability of the 24 phrases and the high correlation between LogMAR and LogRAD leads us to expect a good reproducibility of the reading acuity evaluations. For the "Radner Reading Charts" we have shown that print size is the main reason for changes of reading speed.

Key words visual acuity - reading acuity chart - reading acuity - reading speed

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S. 182-185 (Art. 387)

Sympathetic ophthalmia 50 years after penetrating injury
Case report
Kerstin Hellmund, Annelies Frühauf, Theo Seiler, Gottfried OH Naumann

Background Sympathetic ophthalmia is a rare form of autoimmune uveitis and manifests in 90% of cases within the first year after penetrating injuries or surgical interventions.

Patients and Methods In the present case the sympathetic ophthalmia started 50 years after a penetrating injury by a shell splinter. The injured eye was amaurotic and phthitic and the sympathizing eye showed an anterior uveitis. After an initial treatment with local and systemic corticosteroids the uveitis improved. The clinical diagnosis of sympathetic ophthalmia was made after a second inflammation course with substantial visual loss and subtotal chorioidal detachment. After enucleation of the exciting eye the diagnosis was confirmed by histological examination. An immunosuppressive therapy including azathioprine and cyclosporine became necessary to control the uveitis.

Results After enucleation the corticosteroid treatment was not sufficient. Additional therapy with azathioprine resulted in a recovery of the symptoms but had to be stopped because of adverse reactions. The alternative therapy by means of cyclosporine was tolerated well, but dose reduction was difficult because of recurrences. After a 30 month lasting cyclosporine therapy the patient shows stabile results since 6 months with visual acuity of 20/30.

Conclusions The present case report demonstrates that a delayed onset of sympathetic ophthalmia 50 years after initial trauma may occur but can be controlled by an immediate, high dose immunotherapy.

Key words autoimmune uveitis - sympathetic ophthalmia - azathioprine therapy - cyclosporine therapy

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S. 186-187 (Art. 367 DF)

Acute tumour of the lower lid due to a spontaneous hemorrhage caused by an occult vascular malformation
Jens Martin Rohrbach, Herwig Landenberger, Dietmar Seitz

Purpose To present an unusual acute tumour of the lid.

Patient A 37-year-old female physician presented with a swelling and a slight hematoma of the right lower lid. Palpation revealed two firm painless nodules under an intact epidermis. The patient confirmed that the lesion had developed within only one day without a preceding trauma. Both eyes were morphologically and functionally normal. Motility was free, and there was no exophthalmus. After three weeks the palpable nodules had not changed substantially. Magnetic resonance imaging disclosed a space-occupying lesion resembling an old hemorrhage or an inflammation. Excision was performed which revealed a thrombus-like structure. Histology showed multiple endothelium-lined vessels that were densely filled with erythrocytes, hemorrhages within the connective tissue, and old hemosiderin deposits. However, no thrombus could be found.

Conclusion Although thrombosis was the preferred diagnosis on clinical findings, histology led to the diagnosis of a spontaneous hemorrhage most likely caused by an occult vascular malformation.

Schlüsselwörter Akuter Tumor - Lid - Spontane Blutung - Vaskuläre Malformation - Thrombose

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