Immunologic graft reactions after nonmechanical corneal trephination using the excimer laser

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

Eyelid reconstruction with tarsomarginal grafts

Summary In the past 3 years, 85 basal cell carcinomas were treated in our clinic using eyelid reconstruction. During the same period, 54 lids were reconstructed after other diseases, mostly after chemical burns. In one of the 54 patients, the upper lid was reconstructed using a tarso-marginal graft after congenital coloboma. Method: In 31 of the 85 patients with basal-well carcinoma (36 %), so much tarsus was lost that a transplantation of tarsus was necessary. Fifteen of the 31 patients were treated with a Hughes-plasty and 16 using a tarsomarginal graft, two in the upper lid. Results: In eight of the remaining 16 cases, the defect was less than one half of length, so that the graft was taken from the second lower lid. In the remaining eight patients, the defect was two thirds of length or longer. In six cases, a 7 mm-graft was taken from the upper lid. As the tarsus from the upper lid measures 10 mm and is thus twice as big as the lower lid tarsus, it was divided into two grafts, resulting in two grafts measuring 7 × 5 mm. They were placed in the lower lid (“double tarsomarginal graft”). The former lower part with lashes was placed in the middle of the lower lid, the former upper part peripherally. In two patients, the defect was healed with three tarsomarginal grafts. A pedicle skin flap was transposed to cover the posterior grafts. Remaining defects were closed with free skin transplants. Conclusion: The tarsomarginal graft permits a short operation time and early rehabilitation of the patients. The disadvantage of the double tarsomarginal graft is that the more valuable upper lid tarsus is used to reconstruct the less valuable lower lid tarsus.      

Clinical use of reversal of mydriasis by dapiprazole

Background: Dapiprazole hydrochloride is an alpha-1-adrenergic inhibitor that anticipates the mydriatic effect of phenylephrine in dilator muscle receptors in a competitive way. The aim of this study was to determine for which indications for mydriasis pupil dilation by phenylephrine alone is sufficient and if the reversal by dapiprazole is convenient and the practical. Material and method: In 286 eyes of 147 outpatients, the pupil was dilated for fluorescein angiography – FLA (100 eyes of 50 patients), examination of the fundus – Fd (99 eyes of 52 patients), central argon laser coagulation – cALC (64 eyes of 32 patients), peripheral argon laser coagulation – pALC (16 eyes of 9 patients) and Nd:YAG capsulotomy (7 eyes of 4 patients) with phenylephrine 10 % eye drops, followed by reversal by dapiprazole 0.5 %. The width and mobility of the pupil were tested at intervals of 10 min. When mydriasis by phenylephrine was insufficient, tropicamide was applied additionally. Results: In 98 % of FLA with scanning laser ophthalmoscope, 75 % of cALC, 76 % of Fd, 62 % FLA with fundus camera and 38 % of pALC, mydriasis could be reached that was sufficient for the indication. Diabetics showed significantly more sluggish pupil mobility (t1/2: P < 0.05 mydriasis, P < 0.005 reversal). The mean duration after using dapiprazole until reaching the starting value ( ± 1 mm) of the pupil was 44.3 ± 26.3 min. In 86 % of the examined eyes, the pupil reached its starting value within 1 h. The subjective degree of satisfaction with the application of dapiprazole was “satisfied” to “very satisfied” (5.4 ± 1.4 points on a scale from 1 to 7 points). Discussion and conclusion: In fundus examination, fluorescein angiography by a laser scanner, diagnostic retinal examination and central laser coagulation, the combination phenylephrine/dapiprazole was most suitable. In our opinion, the combination is less suitable for peripheral argon laser coagulation and fluorescein angiography using a fundus camera.      

Intraocular pseudotumor in a patient with Aids. Block excision, differential diagnosis, histology

Summary Background: Intraocular pseudotumors are a rare event in Aids patients and often pose diagnostic problems. Case report: A 37-year-old patient who had had HIV seroconversion for 7 years was seen to developed progressively growing, multiple, disseminated, subretinal lesions OD > OS, accompanied by exudative retinal detachment and iritis. Since all etiological laboratory diagnostic efforts to detect an infectious, noninfectious and neoplastic systemic lesion failed, a diagnostic and curative therapeutic chorioretinal excisional biopsy specimen of the largest of the tumors (3 × 3 × 2 mm) was taken. The histological work-up demonstrated granulation tissue similar to an intracular pseudotumor without signs of infection, malignancy or reactive lymphoid hyperplasia. This finding resulted in systemic corticosteroid treatment with complete resolution of the lesions in both eyes and no recurrences. Conclusions: An invasive diagnostic procedure in patients suffering from lesions of unknown cause resulting in the institution of an appropriate medical treatment may be beneficial for the integrity and vision of the respective eye.      

Comparative laser flare measurement and fluorophotometry in anterior and posterior uveitis

Summary Recent studies have sought to quantify aqueous flare by laser flare measurement. An increase in aqueous flare caused by a rise of protein concentration was frequently found both in anterior and posterior segment disease. This has been interpreted as a breakdown of the blood – aqueous barrier (BAB). By measuring the diffusion coefficient of the BAB compared to the aqueous flare value in patients with anterior and posterior uveitis, the extent to which the increase in flare value was related to a possible break down of the BAB was examined. Patients: Thirty-nine normal eyes (23–78 years; 41.6 ± 18.6), 18 eyes with anterior uveitis (iritis, iridocyclitis; 18–57 years; 35.2 ± 12.4) and 29 eyes with posterior uveitis (chorioretinitis or retinochorioiditis; 18–51 years; 31.7 ± 10.5). The diffusion coefficient P(a) of the BAB was measured fluorophotometrically, while the flare value was quantified by laser flare measurement. Results: Flare values (1/ms) were found to be significantly increased (p < 0.001) compared to normal eyes (4.6 ± 1.7) both in anterior uveitis (20.9 ± 8.5) and in posterior uveitis (17.4 ± 8.3) but did not significantly differ between them (p = 0.43). The diffusion coefficient P(a) (10^–3/min) of the BAB was not significantly different (p > 0.05) between normal eyes (0.5 ± 0.2) and eyes with posterior uveitis (0.9 ± 0.7), whereas it was significantly increased (p < 0.001) in anterior uveitis (6.5 ± 5.4) compared to the other groups. Conclusions: (1) In posterior uveitis, an increased flare value is not necessarily correlated with a breakdown of the BAB; proteins may enter the aqueous from posterior. (2) Assessing the function of the BAB in posterior segment disease using laser measurement should be carried out with caution; if possible, permeability measurements of the BAB should be undertaken seperately.      

A prospective study investigating the long-term stability of changes in astigmatism following arcuate lamellar keratotomy (ALK): 3-year results

Introduction: The correction of low to moderate astigmatism is possible today by means of photoablation (PRK), while the treatment of moderate and higher astigmatism still involves refractive keratotomy. Experience has shown that cataract surgery, using modern tunnel techniques with self-healing incisions, results in earlier stability in both the refractive outcome and wound healing. In this study, we attempted to combine the advantages of lamellar keratotomy with those of a pair-wise T-incision as arcuate lamellar keratotomy (ALK). Patients and methods: The clinical outcome of 41 patients who underwent ALK was investigate in a prospective study over a period of 3 years. The pre- and postoperative investigations undertaken included the measurement of astigmatism using a Zeiss keratometer, uncorrected visual acuity, and corrected glare vision using a Humphrey autorefractor. All patients had astigmatism between 2.0 and 7.0 D. Together with a uniform arcuate incision, we used 7 mm (n = 26) and 8 mm (n = 15) mm zones for correction. Results: The average preoperative astigmatism was 4.01 ± 1.90 (median, 3.50) D. After a 3-year follow-up the average postoperative astigmatism was 1.59 ± 1.29 (median, 1.38) D. The astigmatic change induced (Jaffé) after 3 years was about 3.23 ± 2.23 (median, 3.16) D. The average uncorrected visual acuity (log MAR) before ALK was 0.20 ± 0.12 (median, 0.22) and after follow-up, 0.41 ± 0.14 (median, 0.39). Corrected glare vision before surgery was 0.23 ± 0.19 (median, 0.10) and afterwards, 0.25 ± 0.22 (median, 0.14). Conclusions: Arcuate lamellar keratomy (ALK) stood the test as a routine clinical procedure for correction of moderate astigmatism with stable postoperative functional outcomes. We did not find impairment of glare vision following this procedure.      

Assessment of refractive change following photorefractive keratectomy: keratometry versus computerized videokeratography

Summary The purpose of this study was to determine which corneal curvature values most closely correlated to change in subjective manifest refraction following excimer laser photorefractive keratectomy (PRK). Methods: Excimer laser PRK was performed on ten eyes of ten patients (mean age: 37.3 years). Preoperative refractive errors ranged from –2.25 to –8.75 diopters. Preoperatively and 1 month postoperatively, we determined the spherical equivalent of the manifest refraction (corrected for a 12 mm vertex distance) and measured corneal power using standard keratometry (Bausch and Lomb keratometer) and computerized videokeratography (EyeSys Corneal Analysis System). We collected five corneal values: standard keratometry, videokeratography-derived simulated keratometric readings calculated using the axial, instantaneous and refractive formulas, and corneal refractive power over the central 3-mm zone (effective refractive power); apart from the traditional refractive index of the cornea (n = 1.3375), we used the refractive value of the anterior corneal stroma (n = 1.376). For each of the five corneal values, we subtracted the change in corneal power from the change in manifest refraction and calculated the means and standard deviations. Results: The mean differences between the refraction and the corneal values for a refractive index of 1.3375/1.376 were: 0.89 ± 0.54^*/1.26 ± 0.59* for standard keratometry; 1.64 ± 0.75^*/1.37 ± 0.7*, 4.03 ± 1.86^*/3.86 ± 1.87*, and 1.16 ± 0.76^*/0.91 ± 0.74* for the axial, instantaneous, and refractive videokeratography values, respectively; and 0.83 ± 1.03^*/0.39 ± 1.08 for the effective refractive power (*, p < 0.05). Conclusions: In our series, only the values for the effective refractive power, calculated with the refractive index of the anterior stroma of the cornea, were not statistically different from the change in manifest refraction.      

Laser of complications in in situ keratomileusis (LASIK)

Background: The incidence and course of intraoperative and postoperative complications of LASIK were investigated. Patients and methods: We consecutively treated 598 eyes (316 patients) using the Automatic Corneal Shaper and the Keracor 117 C excimer laser. One hundred and sixty-three eyes were also available at 12 months. The preoperative spherical equivalent was − 5.31 ± 5.49 D (+ 9 to − 23 D). We evaluated intra- and postoperative complications. Results: Intraoperative complications of keratotomy were observed in 1.3 % (irregular cut, n = 5; free cap, n = 2; incomplete cap, n = 1), and other intraoperative complications in 1.7 % (epithelial defects, n = 7; flap dislocation, n = 1; lateral kanthotomy required, n = 2). None of these complications caused any long-term effects or loss of two or more lines of visual acuity. Postoperative complications were observed in 0.9 % (peripheral epithelial ingrowth, n = 4; keratectasia, n = 1; subretinal neovascularisation, n = 1). Conclusions: The rate of complications in LASIK is low, and intraoperative complications did not cause any significant loss of vision. We observed keratectasia in one eye, which suggests that deep ablations should be avoided, which limits the amount of correction possible.      

Evaluation of retinal hemodynamics by means of digital scanning laser fluorescence angiography in normal-tension glaucoma

Summary Chronic ischemia of the retina and the optic nerve head seems of importance especially in patients with normal-tension glaucoma (NTG). The purpose of this study was to examine the retinal hemodynamics in patients with NTG. Patients: Twenty-five patients with NTG were examined (3 weeks washout period) in this study (age 58 ± 16 years). The arteriovenous passage (AVP) time and arterial and venous diameters from scanning laser fluorescein angiograms were evaluated by means of digital image analysis. Results: The AVP time in patients with NTG (2.78 ± 1.1 s) was significantly prolonged (P < 0.0001) compared with healthy subjects (1.58 ± 0.4 s). No significant correlation was found between arterial and venous diameters, intraocular pressure, blood pressure or calculated perfusion pressure and retinal arteriovenous passage time. Conclusion: Patients with NTG showed prolonged retinal passage, which could cause chronic hypoxia. This prolongation of circulation is not correlated with any of the clinical parameters. Thus, a circulatory defect might be a primary factor in the pathogenesis of NTG.      

Correction of myopic astigmatism by combined treatment with PRK and T-incision and photoastigmatic refractive keratectomy

Background: In contrast to the correction of simple myopia there is no widely accepted technique for the correction of myopic astigmatism. Currently two techniques are available: the photoastigmatic refractive keratectomy (PARK) and the combination of arcuate keratotomies with standard PRK (PRK-T). Methods: In two groups, 67 patients underwent a correction of myopic astigmatism in a total of 87 eyes (19 by PRK-T and 68 by PARK), and were followed for 1 year. The spherical equivalent was − 6.7 D in both groups and the refractive astigmatism ranged from − 1.0 to − 6.5 D. The PARK procedure was performed by means of an elliptic ablation (Kertom I, Schwind) with a 5.8 × 8.1 mm zone. The PRK-T technique consisted of two arcuate keratotomies with a free optical zone of 7 mm and a standard myopic PRK at least 6 weeks later. Results: The 1 year follow-up was completed in 57 out of 87 eyes included in the study. At 1 year post-operation, 83 % of the PRK-T group and 80 % of the PARK group had an uncorrected visual acuity of 20/40 or better. The refractive astigmatism was reduced by 76 % in the PRK-T group and by 67 % in the PARK group. The spherical equivalent was − 0.59 ± 1.1 D at 1 year after PRK-T and − 0.28 ± 1.04 D after PARK. In three eyes of the PARK group (6.7 %) a visual loss of more than one Snellen line occured. Two of these eyes had a preoperative myopia of more than − 6 diopters. Conclusion: Both techniques have the potential to reduce myopic astigmatism, however, the success rate is not as high compared to spherical PRK. Also, the complication rate of 2.5 % in corrections to − 6 D is significantly higher than that with spherical myopic PRK.      

Bilateral cystoid macular edema following successful treatment of AIDS-associated CMV retinitis

Background: Cystoid macular edema (CME) in AIDS patients with inactive cytomegalovirus (CMV) retinitis is an uncommon but potentially sight-threatening complication. The pathogenesis of CME in these patients is unclear. This study tries to identify possible risk factors by analyzing the charts of five patients. Methods: Ten eyes of 5 patients that finally developed CME were followed for an average of 18 months. The initial retinal lesions, their response to antiviral treatment, the development of CME, and the patients' immune status were prospectively monitored. Results: CMV retinitis was diagnosed at a median CD4+ count of 3 cells/mm³ (range 0–11). All eyes responded to the initial systemic anti-viral treatment. At the onset of CME, CMV retinitis was controlled by antiviral maintenance therapy in all patients [ganciclovir (n = 2), cidofovir (n = 2), foscarnet (n = 1)]. The median time between diagnosis of CMV retinitis and onset of CME was 11.5 months (range 5–24). Development of CME was associated with significant visual loss: acuity ranged from 0.05 to 0.7 when CME was first noticed, compared to 0.8–1.25 at diagnosis of CMV retinitis. Duration of inflammation, size or zone of retinal necrosis did not favor the development of CME, neither did the antiviral therapy. A weak correlation of CME development and immune status (expressed as increase of CD4+ cells) was found. Due to systemic corticosteroids CME resolved. Conclusions: CME is a new visual threat to AIDS-patients with CMV retinitis whose immune status improved under the latest combined antiretroviral therapy. Therapy with oral corticosteroids may positively influence this condition.      

Prospective controlled evaluation on radiotherapy of subfoveolar neovascularization

Summary Despite the successful therapy of subretinal neovascular membranes by laserphotocoagulation there are many problems to be overcome. In the case of subfoveolar neovascularization, photocoagulation leads to a sudden decrease in visual acuity.Recently radiotherapy is considered as an alternative. Complications and effectivity were evaluated in this prospective and randomized trial. The initial results are presented. Patients and methods: There are 76 patients (51 women, 25 men, average age 77.7 ± 8.6 years) included in the prospective randomized study. All of them show subfoveolar neovascular membranes in FLA and a decrease in visual acuity between 0.05 and 0.5. They were randomly assigned to either the radiotherapy or the control group. Radiotherapy was done within 6 days by 6 × 2 Gy (6 MV photons). The follow-up was at 4 weeks, after 3 months, after 6 months and then every 6 months after the end of radiotherapy. On average the follow-up is at 15.1 months. Results: Concerning age and visual acuity before therapy, the control group and the radiotherapy group were not significantly different. At 4 weeks after radiotherapy, visual acuity was 0.13 ± 0.46 (LogMAR). After 12 months, visual acuity at a distance was 0.11 ± 0.30 in the therapy group and 0.09 ± 0.13 (P = 0.838) in the control group. Patients with a preoperative visual acuity better than 0.2 improved more after radiotherapy. Metamorphopsy improved in 75 % of the therapy group. The following complications could be observed: In the control group 3 patients suffered subretinal bleeding, in the radiotherapy group 3 patients, respectively. Conclusions: At present, the follow-up is too short to recommend radiotherapy as a standard procedure in the case of subfoveolar neovascularization. The results in patients with a better preoperative visual acuity encourage us to continue this study.      

Autologous platelet concentrate in the treatment of macular holes

Background: Recent studies have shown the usefulness of pars plana vitrectomy with the use of growth factors in the treatment of macular holes. Autologous platelet concentrates contain many growth factors to stimulate glial wound healing. Patients: Nineteen patients with idiopathic macular hole underwent vitrectomy, membrane peeling, air injection and installation of autologous platelet concentrate (0.1 ml). The platelet concentrate contained a mean of 1.8 × 10⁹ platelets/ml. Results: The anatomic success rate in stage 2 macular hole was 100 %, in stage 3, 82 % and in stage 4, 50 %. Visual acuity improved in all patients with stage 2 (two lines) and in 73 % of stage 3 at least (one line). Conclusion: Platelets are effective in the treatment of macular holes due to the high amount of different growth factors (PDGF, EGF, bFGF, IGF-1) which have a high affinity binding to Müller cells helping to seal the hole by photoreceptor adaption.      

Influence of postoperative topical application of miotics after cataract extraction on intraocular pressure and the blood-aqueous barrier

Background: In the present study we evaluated the influence of topical miotics on intraocular pressure and the blood-aqueous barrier after uncomplicated phacoemulsification and PC-IOL implantation. Patients and methods: Fifty-two eyes were randomized into 2 groups: with miotics (n = 28) and without miotics (n = 24). The IOP was measured before, 6 h, 1 and 2 days after surgery. Measurement of aqueous flare was performed before and on days 1 and 2 after surgery. Patients with glaucoma, PEX or previous intraocular surgery were excluded. Results: In the group without miotics the IOP was 17.9 mm Hg (± 3.34) 6 h postoperatively; in the second group it was 15.5 mm Hg (± 3.25); P = 0.04. On the first postoperative day the IOP measured in the group without miotics was 15.3 mm Hg (± 2.70) and with miotics 13.0 mm Hg (± 2.28); P = 0.007. On the second day in the group without miotics the IOP was 13.9 mm Hg (± 3.05) and with miotics 12.60 mm Hg (± 2.19); P = 0.53. The changes in aqueous flare on the first and second day after surgery showed no significant influence of miotics on the blood-aqueous barrier (P > 0.05). Conclusions: Immediate postoperative application of topical miotics led to a small yet significant reduction of the IOP during the first 24 h after surgery. Our data suggest that there is no need for pharmacological reduction of the IOP after uncomplicated cataract surgery.      

Comparison of the efficacy of ER-YAG laser sclerostomy ab externo versus trabeculectomy in the treatment of patients with primary open – angle glaucoma

Purpose: This study was conducted to compare the efficacy of the Er-YAG laser sclerostomy ab externo versus trabeculectomy in the treatment of primary open – angle glaucoma. Methods: Twelve patients with POAG underwent ab externo laser sclerostomy using an Er-YAG laser (Sklerostom 2.9?; λ = 2940 nm, t = 200 μs, 2 Hz, 400 μm, 15 mJ). Only local medication was used, and there were no risk factors for failure. As a control group 12 patients out of 248 standardized trabeculectomies were matched in terms of age, sex, diagnosis and local medications. No antimetabolites were used in either group. Results: After a follow-up of 9 months in the sclerostomy group 53 %; (7/12; P = 0.03) showed a patent fistula in comparison of 100 % in the trabeculectomy group. There was a significantly lower mean IOP during the first postsurgical week in the group of sclerostomies (3.6 ± 1.5 mmHg versus 7.5 ± 2.7 mmHg; P = 0.0001) with a higher incidence of choroidal detachments (9/12 versus 2/12; P = 0.004). The choroidal detachments lasted longer in the sclerostomy group (3.5 months versus 0.3 months; P = 0.014). Iris incarcerations were found only in sclerostomies (7/12; P = 0.05). Conclusions: Based on these findings, Er-YAG laser sclerostomy prooved to be less effective than trabeculectomy in the treatment of glaucoma patients. Er-YAG laser sclerostomies were associated with a higher incidence of postsurgical complications such as hypotony, choroidal detachments and iris incarcerations. At this point Er-YAG laser sclerostomy is not superior to conventional trabeculectomy.      

Acute hypopyon uveitis in a patient with acquired immunodeficiency syndrome treated for systemic Mycobacterium avium complex (MAC) infection with rifabutin

Background: Hypopyon-uveitis has been identified as a dosage-dependent side effect in patients with acquired immunodeficiency syndrome who are treated for Mycobacterium avium complex (MAC) infection with systemic rifabutin. Patients and methods: We report a 38-year-old female AIDS patient with bilateral hypopyon uveitis under therapy with rifabutin in combination with clarithromycin and indinavir. Results: At the time of presentation of the bilateral hypopyon uveitis the patient was treated with rifabutin (300 mg/day), clarithromycin (1000 mg/day) and ethambutol (1000 mg/day) for an M. avium complex infection. Also, the patient received the protease inhibitor indinavir. The rifabutin dose was reduced to 150 mg/day. Hypopyon and inflammation resolved under therapy with steroids. Conclusions: The concomitant use of rifabutin, clarithromycin, and protease inhibitors may lead to hypopyon uveitis. Reduction of dosage of rifabutin (150 mg/day) and treatment with topical steroids are required.      

The effects of changed biomechanical parameters on measurements of intraocular pressure in keratoconus patients

Background: Keratoconus is associated with changes in the corneal structure, such as defects of Bowman's layer, a decrease of corneal thickness etc. They result in alterations of some of the biomechanical parameters of the cornea, namely, rigidity and elasticity. The present study was performed to examine how impression tonometry and applanation tonometry for determination of intraocular pressure (IOP) are affected by the changed biomechanical parameters associated with keratoconus. Patients and methods: We examined 20 normal subjects (40 eyes) and 17 keratoconus patients (25 eyes). The corneal thickness was measured by ultrasound pachymetry in the corneal center. In the keratoconus patients, an additional measurement was made at the conus peak. The corneal curvature was determined using the TMS keratoscope. The IOP measurements were made with the Schi?tz tonometer (10 g). For comparison, additional IOP measurements in the corneal center and, in the keratoconus group, on the conus peak were made with the applanation tonometer. Results: The normal subjects had a central corneal thickness of 548 ± 30 μm, compared to 505 ± 42 μm in the corneal center and 425 ± 41 μm on the conus peak in keratoconus patients. The average corneal curvature was 43.3 ± 1.8 D in the normal subjects and 47.8 ± 4.1 D in keratoconus patients. Applanation tonometry produced results on 11.33 ± 1.43 mm Hg in the normal group (corneal center) compared to values of 12.00 ± 2.55 mm Hg (corneal center) and 7.30 ± 1.95 mm Hg (conus peak) in the keratoconus cohort. The coefficient of rigidity was 0.0236 ± 0.0026 μl⁻¹ in the normal subjects, compared to 0.0173 ± 0.0050 μl⁻¹ in the keratoconus patients. Conclusion: The morphological changes associated with keratoconus may cause tonometry errors.      

Deep lamellar keratoplasty with the guided trephine system for transplanting fullthickness donor tissue

Background: Despite the fact that deep lamellar keratoplasty (DLKP) is less invasive than to penetrating keratoplasty (PKP), this procedure is rarely performed. We therefore investigated whether or not the DLKP technique we employed can achieve stable improvement of visual acuity. Materials and methods: Thirty-three eyes underwent TLKP for treatment of superficial corneal pathology. The donor tissue transplanted was suitable for PKP. The donor lenticule was obtained on the artificial chamber of the guided trephine system (GTS). The recipient cornea was trephined with the same trephine to a depth of 680 μm. Manual dissection was performed with a bevel-up blade. The donor lenticule with the endothelium peeled off was then sutured in with a 10 × 0 nylon double-running antitorque suture. Cortisone-antibiotic eye drops were administered postoperatively. Results: Throughout the series no complications occurred. The mean best corrected visual acuity (BSCVA) over glasses was 0.29 ( ± 0.21) preoperatively, 0.1 ( ± 0.11) at 1 week, 0.33 ( ± 0.14) at 1 month, 0.5 ( ± 0.13) at 6 months, 0.61 ( ± 0.16) at 1 year and 0.63 ( ± 0.15) at 2 years. Clinically, we observed two subpopulations. In the first group of 87 % of the cases, mean BSCVA was 0.67 ( ± 0.07) at 6 months. The remaining cases (BSCVA ≤ 0.25 at 6 months) achieved a mean BSCVA of only 0.2 ( ± 0.04) at 1 year. Mean corneal astigmatism measured 2.93 D ( ± 1.62) preoperatively, 2.69 D ( ± 1.18) at 1 month, 2.09 D ( ± 1.07) at 1 year, and 2.22 D ( ± 1.11) at 2 years. We did not observe any graft rejection. Conclusion: The technique reported for DLKP provides excellent matching of donor lenticule and recipient bed. Separation of donor and recipient stroma prevents interface healing. DLKP appears to be a safe procedure for the surgical treatment of superficial corneal pathology and may offer a clinically applicable alternative to PKP.      

Clinical, fluorescein angiographic and demographic aspects in central serous chorioretinopathy

Summary The purpose of this retrospective study was to analyze the demographic characteristics of central serous chorioretinopathy (CSC). Methods: Findings of 100 consecutive subjects with CSC were evaluated. Clinical and fluorescein angiographic findings, demographic characteristics, and visual acuity were analyzed. Results: The age of the patients ranged from 28 to 68 years with a mean of 43 years. No significant sex differences were found concerning age and other parameters. The highest age peak was in the group of women. The male to female ratio was 5 : 1. Patients with chronic CSC were significantly older (P = 0.015) than patients with the other angiographic findings. Median visual acuity was 0.5. In 40 % bilateral characteristics of CSC were found. Clinical and fluorescein angiographic findings showed no significant correlation with visual acuity. Conclusion: The range of age distribution in CSC is wide. In older patients distinguishing CSC from age-related macular degeneration can be difficult.      

Epidemiology of toxocariasis – environmental investigations

Summary Due to the large number of differential diagnostic possibilities, the etiology of endogenous uveitis is still hard to determine. One reason for uveitis may be the occurrence of parasites. However, too little attention is paid to this underlying disease. Methods: To identify certain sources of infection, ovoscopic probes of 98 dog feces from the urban area of Halle were taken. The material was collected from children's playgrounds, parks and swimming pools. A retrospective analysis of patient case data from the records of the University Eye Hospital for the years 1986–1995 complemented the environmental and parasitological examination of patients with Toxocara canis and T. cati infections. Results: From the ovoscopic examinations, 16 % of the fecal samples contained T. canis eggs. Seventeen percent contained coccicidal sporocysts. Eggs of Trichuris vulpis and not clearly identifiable nematodal larvae were found in 1 % of the samples. The reasons for the morphology was, in one instance, suspected Echinococcus eggs. The fact that 12 or 15 parasitologically positive dog excrement samples were taken from the immediate vicinity of children's playgrounds and another three directly from these grounds should be regarded as particularly critical. The investigated patient case data records revealed for the period studied nine uveitic patients with T. canis infection. The diagnosis was based on the larva precipitation test in all cases. After correct diagnosis and appropriate treatment, the prognosis was favorable. The specific treatment had to be repeated in two patients. Conclusions: The environmental parasitological study presented proves the relatively high prevalence of pathogenic causal agents in dog excrement samples from the area of urban recreation and leisure grounds, in particular, children's playgrounds. Parasite infestation is a mirror of the efficiency of hygienic and social measures. Public health education must be reinforced. Differential diagnosis of chronic endogenous eye diseases must pay more attention to infections by parasites.