PubMed Health⌕ Search

Biomedical subjects

M Küchle

Publications and source records attributed to M Küchle.

At least 73 records · Page 4Linked to original sources
PubMed1999

[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.

Blood-Aqueous Barrier↗
PubMed1999

Quantification of blood-aqueous barrier breakdown after photorefractive keratectomy for myopia.

BACKGROUND: Photorefractive keratectomy (PRK) using the excimer laser is a well-established surgical technique for correction of mild to moderate myopic refraction errors in case of spectacle or contact lens incompatibility. As it is still uncertain whether this procedure causes intraocular inflammatory changes, it was the purpose of this study to quantify breakdown of the blood-aqueous barrier following PRK and to look for possible correlations with clinical parameters. PATIENTS AND METHODS: Aqueous flare was quantified using the laser flare-cell meter after medical pupil dilation preoperatively and on days 1, 3 and 7 as well as 1 month and 3 months following PRK with a 193-nm excimer laser (MEL 60, Aesculap-Meditec) in 37 eyes of 22 patients. The preoperative spherical equivalents were -4.4 +/- 3.1 D (range -1.5 to -8.0 D). Pre-, intra- and postoperative treatment was standardized. RESULTS: Preoperatively, aqueous flare values were 3.9 +/- 0.8 photon counts/ms and showed no significant correlation with the spherical equivalent (p > 0.1). Postoperatively, aqueous flare rise was very small with flare values not significantly higher than preoperative values. All postoperative flare values were below the normal limit (< 8.0 photon counts/ms). Flare was highest on day 3 after PRK surgery. There was no statistically significant correlation between aqueous flare and depth of stromal ablation. The number of aqueous "cells" did not increase following PRK at any postoperative follow-up examination. CONCLUSION: Our results indicate that PRK in mild to moderate myopia does not cause a significant breakdown of the blood-aqueous barrier.

Adult↗
PubMed1999

Free-running erbium:YAG laser for nonmechanical trephination in penetrating keratoplasty: first results of experimental trephination of human donor corneas.

BACKGROUND: A study was carried out to evaluate the potential suitability of a free-running erbium:YAG 2.94-microm laser for trephination of human corneas in penetrating keratoplasty. METHODS: Two human donor corneas were placed in an artificial anterior chamber and moved with an automated rotation device (one rotation per minute). An erbium:YAG laser beam (pulse duration 400 micros, repetition rate 2/s, energy density 2.5 and 15.0 J/cm(2)) was focused on the outer edge of a round ceramic mask placed on the human donor corneas for ablation of tissue. RESULTS: With a fluence of 15.0 J/cm(2), perforation was achieved after 500 pulses. Perpendicular central cut edges with mild stromal ridges and, by light microscopy, a 12 to 45-microm area of stromal thermal effects and focal endothelial changes up to 200 microm central to trephination were observed. CONCLUSIONS: The erbium:YAG laser could be a promising "low-cost alternative" to the excimer laser for nonmechanical trephination in penetrating keratoplasty. Further studies will have to focus on reduction of thermal damage and on wound healing.

Animals↗
PubMed1999

Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy.

OBJECTIVE: To assess the validity of corneal power measurement and standard intraocular lens power (IOLP) calculation after photorefractive keratectomy (PRK). DESIGN: Nonrandomized, prospective, cross-sectional, clinical study. PARTICIPANTS: A total of 31 eyes of 21 females and 10 males with a mean age at the time of surgery of 32.3 +/- 6.6 years (range, 24.4-49.5 years). INTERVENTION: Subjective refractometry, standard keratometry, TMS-1 corneal topography analysis, and pachymetry were performed before and 15.8 +/- 10.4 months after PRK for myopia (n = 24, -1 .5 to -8.0 diopters [D], mean -5.4 +/- 1.9 D) or myopic astigmatism (n = 7, sphere -2.0 to -7.5 D, mean -4.4 +/- 1.9 D; cylinder -1.0 to -3.0 D, mean -1.9 +/- 0.7 D). The IOLP calculations were done using two different formulas (SRK/T and HAIGIS). MAIN OUTCOME MEASURES: Keratometric power (K) and topographic simulated keratometric power (TOPO) as measured (Kmeas, TOPOmeas) and as calculated according to the change of power of the anterior corneal surface or according to the spherical equivalent change after PRK (Kcalc, TOPOcalc), IOLP for emmetropia, and postoperative ametropia for calculated corneal powers were assessed in a model. RESULTS: After PRK, mean Kmeas and TOPOmeas were significantly greater (0.4-1.4 D, maximum 3.3 D) than mean KRcalc and TOPOcalc (P < 0.0001). On average, the relative flattening of the cornea after PRK was underestimated by 14% to 30% (maximum, 83%) depending on the method of calculation. The mean theoretical IOLP after PRK ranged from + 17.4 D (SRK/T, TOPOmeas) to +20.9 D (HAIGIS, Kcalc) depending on the calculation method for corneal power and IOLP calculation formula used. For both formulas, IOLP values using keratometric readings were significantly higher (>1 D) than IOLP values using topographic readings (P < 0.0001). The theoretically induced mean refractive error after cataract surgery ranged from +0.4 to +1.4 (maximum, +3.1) D. Corneal power overestimation and IOLP underestimation correlated significantly with the spherical equivalent change after PRK (P = 0.001) and the intended ablation depth during PRK (P = 0.004). CONCLUSIONS: To avoid underestimation of IOLP and hyperopia after cataract surgery following PRK, measured corneal power values must be corrected. The calculation method using spherical equivalent change of refraction at the corneal plane seems to be the most appropriate method. In comparison with this method, direct power measurements underestimate corneal flattening after PRK by 24% on average. Use of conventional topography analysis seems to increase the risk of error. However, because this study is retrospective and theoretical, there is still a need for a large prospective investigation to validate the authors' findings.

Adult↗
PubMed1999

Nonmechanical corneal trephination with the excimer laser improves outcome after penetrating keratoplasty.

OBJECTIVE: To assess the impact of nonmechanical trephination on the outcome after penetrating keratoplasty (PK). DESIGN: Prospective, randomized, cross-sectional, clinical, single-center study. PATIENTS: A total of 179 eyes of 76 females and 103 males, mean age at the time of surgery 50.6 +/- 18.5 (range, 15-83) years. Inclusion criteria were (1) time interval from October 1992 to December 1997; (2) one surgeon (GOHN); (3) primary central PK; (4) Fuchs dystrophy (diameter, 7.5 mm) or keratoconus (diameter, 8.0 mm); (5) graft oversize, 0.1 mm; (6) no previous intraocular surgery; and (7) 16-bite double-running diagonal suture. INTERVENTION: In a randomized fashion, eyes were assigned either to trephination with the 193-nm Meditec excimer laser (manually guided beam in patients, automated rotation device of artificial anterior chamber in donors) along metal masks with eight orientation teeth/notches (EXCIMER: 53 keratoconus, 35 Fuchs dystrophy; mean follow-up, 37 +/- 16 months) or with a hand-held motor trephine (Microkeratron; Geuder) ( CONTROL: 53 keratoconus, 38 Fuchs dystrophy; mean follow-up, 38 +/- 14 months). Subjective refractometry (trial glasses), standard keratometry (Zeiss), and corneal topography analysis (TMS-1; Tomey) were performed before surgery, before removal of the first suture (15.2 +/- 4.2 months), and after removal of the second suture (21.4 +/- 5.6 months). MAIN OUTCOME MEASURES: Keratometric and topographic net astigmatism as well as refractive cylinder; keratometric and topographic central power; best-corrected visual acuity (VA); surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) of the TMS-1. RESULTS: Before suture removal, mean refractive/keratometric/topographic astigmatism did not differ significantly between EXCIMER (2.5 +/- 1.8 diopters [D]/3.4 +/- 2.8 D/4.7 +/- 3.1 D) and CONTROL groups (3.0 +/- 1.8 D/3.7 +/- 2.4 D/4.3 +/- 2.1 D). After suture removal, respective values were significantly lower in the EXCIMER group (2.8 +/- 2.0 D/3.0 +/- 2.1 D/3.8 +/- 2.6 D) than in the CONTROL group (4.2 +/- 2.4 D/6.1 +/- 2.7 D/6.7 +/- 3.1 D) (P < 0.0009). In the EXCIMER versus CONTROL group, mean VA increased from 20/100 versus 20/111 (P > 0.05) before surgery, to 20/31 versus 20/38 before (P = 0.001) and to 20/28 versus 20/39 (P < 0.00001) after suture removal. Mean spherical equivalent was significantly less myopic in the EXCIMER group before (-0.9 +/- 3.6 D vs. -2.6 +/- 3.4 D) (P = 0.01) and after suture removal (-1.4 +/- 3.1 D vs. -2.4 +/- 3.5 D) (P = 0.02). Mean SRI (P = 0.04) and PVA (P = 0.007) were significantly more favorable in the EXCIMER versus CONTROL group after suture removal (0.91 +/- 0.45 and 0.82 +/- 0.15 vs. 1.05 +/- 0.46 and 0.73 +/- 0.18). CONCLUSIONS: Postkeratoplasty results seem to be superior using nonmechanical excimer laser trephination. Thus, this methodology is recommended as the procedure of first choice in avascular corneal pathologies requiring PK.

Adolescent↗
PubMed1999

Nonmechanical excimer laser penetrating keratoplasty for perforated or predescemetal corneal ulcers.

OBJECTIVE: To review the authors' results using nonmechanical excimer laser trephination in penetrating keratoplasty for perforated or predescemetal corneal ulcers. DESIGN: Noncomparative, consecutive, interventional case series. PARTICIPANTS: Thirty-two patients with perforated (17) or deep (15) corneal ulcers (9 bacterial, 5 acanthamoebal, 10 herpetic, 3 associated with rheumatoid arthritis, 5 other) necessitating immediate tectonic keratoplasty. INTERVENTION: Penetrating tectonic keratoplasty with excimer laser trephination was performed along metal aperture masks in donor and recipient corneas. MAIN OUTCOME MEASURES: Clinical results including intraoperative and postoperative complications were evaluated. RESULTS: Trephination was possible in all eyes without perforation of predescemetal ulcers or extrusion of intraocular contents. No eyes with bacterial or acanthamoebal ulcers showed persistence or recurrence of infection. One eye showed recurrent epithelial herpetic keratitis. Best-corrected postoperative visual acuity ranged from 20/700 to 20/20 (median, 20/58), with 30 of 32 eyes achieving improvement of best visual acuity during follow-up (mean, 22.4 months) and with 12 of 32 eyes reaching a visual acuity of 20/40 or greater. Eyes with bacterial or acanthamoebal ulcers showed best results. Episodes of graft rejection occurred in nine eyes and resulted in irreversible opacity of the graft in seven cases. None of the eyes lost all vision, developed endophthalmitis, or had to be enucleated. CONCLUSIONS: Nonmechanical trephination is a useful technical refinement of tectonic penetrating keratoplasty à chaud for perforated or deep progressive corneal ulcers. This technique greatly facilitates exact trephination under these difficult surgical conditions and might possibly improve the prognosis of this procedure.

Adult↗
PubMed1999

[Transplant endothelium and measuring corneal thickness after non-high-risk keratoplasty with briefly or long-term preserved corneal donor tissue].

PURPOSE: The corneal endothelial cell density is essential for the pump function and the transparency of grafts after penetrating keratoplasty (PK). The purpose of this study was to assess corneal endothelial cell density after non-high-risk PK and to check for possible correlations with storage parameters of the donor corneas using two different storage methods. PATIENTS AND METHODS: Endothelial cell density (specular microscope EM 1100, TOMEY, Erlangen) and central corneal thickness (ultrasonic pachymetry SP-2000, TOMEY, Erlangen) were assessed 6 weeks, 3, 6, 9 months and one year postoperatively in 168 non-high-risk PKs. Short-term-preserved donor corneas were used in 89 patients, whereas in 79 patients organ-cultured corneas were used. The donor trephination was performed from the epithelial side using an artificial anterior chamber. The postoperative treatment with topical steroids was standardized. The mean donor post-mortem time was 9.6 +/- 8.0 hours for short-term-preserved and 17.6 +/- 10.5 hours for organ-cultured corneas (p < 0.0001). The storage time was 71 +/- 49 and 380 +/- 167 hours (p < 0.0001), respectively. RESULTS: Endothelial cell density did not differ significantly between the two storage methods (p > 0.05). At 6 weeks postoperatively, the mean endothelial cell density was 2042 +/- 675 cells/mm2 for short-term-preserved corneas and 1972 +/- 522 cells/mm2 for organ-cultured corneas (p = 0.7). Endothelial cell density did not decrease significantly (p > 0.05) within the observation period of 12 months in both groups (after 12 months: 1868 +/- 957 cells/mm2 and 1638 +/- 643 cells/mm2, respectively). The mean corneal thickness was 542 +/- 50 microns for short-term-preserved and 541 +/- 55 microns for organ-cultured corneas and remainded unchanged during the follow-up of 12 months (542 +/- 42 microns and 521 +/- 43 microns, respectively). Neither the group of short-term-preserved corneas nor organ-cultured corneas showed a significant correlation between endothelial cell density or central cornea thickness with post-mortem time or with storage time of the donor corneas at any postoperative stage (p > 0.1). CONCLUSION: During the first year after PK, only a small decrease in endothelial cell density was observed in comparison with the 6-weeks finding. The storage method does not seem to affect the short-term changes of endothelial cell density. Further long-term studies are necessary to assess the clinical relevance of these observations.

Adult↗
PubMed1999

[Development of visual acuity in the early phase after photorefractive keratectomy in myopia].

BACKGROUND: Photorefractive keratectomy (PRK) using the excimer laser is an accepted surgical technique for correction of myopic refraction errors in case of spectacle or contact lens incompatibility. The purpose of this study was to assess the development of uncorrected (UVA) and best-corrected visual acuity (CVA) in the early course following PRK. PATIENTS AND METHODS: 48 eyes of 29 patients that underwent myopic photorefractive keratectomy using 193 nm excimer laser (MEL 60, Aesculap-Meditec) were included in this study. The mean preoperative spherical equivalent was -5.3 +/- 2.4 diopters (D) (range -1.75 to -9.5 D). Pre-, intra- and postoperative treatment was standardized. The median time interval to complete epithelial closure was 2 days. According to their spherical equivalent, patients were divided in two groups: group 1 with myopia < or = 6 D (n = 28), group 2 with myopia more than 6 D (n = 20). Examination of UVA and CVA were performed preoperatively and on days 3, 7 as well as 1 month, 3 and 6 months postoperatively. RESULTS: On day 3 after surgery UVA was 0.43 +/- 0.21 for group 1 with myopia < or = 6 D, and 0.36 +/- 0.14 for group 2 with myopia more than 6 D. The UVA was stable after 3 months (0.92 +/- 0.29 and 0.66 +/- 0.20, respectively), the CVA was stable after 1 month (1.04 +/- 0.18 and 0.86 +/- 0.19, respectively). After surgery, the UVA increased by +0.73 +/- 0.25, whereas the CVA increased by +0.05 +/- 0.10 for the whole group. The difference comparing pre- and postoperative UVA was significantly higher in group 1 (0.81 +/- 0.22) than in group 2 (0.60 +/- 0.26) (p = 0.002). However, postoperative CVA values were not significantly different from preoperative values in both groups after 6 months (p = 0.3). CONCLUSION: Useful uncorrected visual acuity is normally achieved at day 3 after PRK in eyes with mild to moderate myopia. With higher degrees of myopia the uncorrected visual acuity does increase slower towards a lower level. One of the reasons for this phenomenon might be a significant regression of the refractive effects during the first half year after surgery.

Adult↗
PubMed1999

[Clearing of the host cornea after penetrating keratoplasty for pseudophakic bullous keratopathy].

BACKGROUND: In this study, we have focussed on the clearing of the host cornea after successful penetrating keratoplasty (PK) for pseudophakic bullous keratopathy and the clinical factors that may influence this phenomenon. PATIENTS AND METHODS: We recruited the study group out of all keratoplasties performed in our department between 1984 and 1996 using the following criteria: (1) pseudophakic bullous keratopathy that involved the whole host cornea preoperatively, (2) no additional ocular diseases, (3) all operations performed before January 1st 1996, (4) sufficient photodocumentation, (5) complete clinical records, (6) clear graft at the end of the follow-up period. Using these criteria, 48 patients (28 females and 20 males; mean age at the time of surgery 72.7 +/- 8.8 years) were included in the study group. Donor age ranged from 34 to 86 years (mean age 65.8 +/- 12.0 years). The opacity of the host cornea was graded from 0 to 3 (0 = clear cornea; 3 = total opacity) within a circular zone of 1 mm diameter adjacent to the graft in four quadrants (I-IV). Finally, an index for the mean opacity index was calculated [TG = (I + II + III + IV)/4] and correlated with clinical parameters. RESULTS: The index for the mean opacity was 2.8 preoperatively. After a mean follow-up of 9.6 +/- 12.3 months, the index decreased significantly to 1.8 (p = 0.01). Mean visual acuity before PK was 20/400, at the end of the follow-up it was 20/50. The index of opacification was significantly correlated with patients age (p = 0.03; r = 0.2) and inversely with the follow-up period (p = 0.001; r = -0.6) and with the visual acuity at the end of the follow-up period (p = 0.05; r = -0.2). Using the 193-nm excimer laser for donor and host trephination led to a higher clearing of the host circular zone (mean opacification index 1.7) than mechanical trephination (mean 2.1) (p = 0.01). CONCLUSION: Our results indicate that expansion of donor endothelial cells onto host's Descemet's membrane is possible and successful with respect to clearing of the host cornea in pseudophakic bullous keratopathy. Nonmechanical excimer laser trephination of donor and host from the epithelial side seems to promote this phenomenon due to a better apposition of the cut surfaces.

Aged↗
PubMed1999

[Results after cyclodiathermy: report on 29 eyes].

BACKGROUND: Persisting angle-closure glaucomas with circular anterior synechia and lost anterior chamber are at the moment an unsolved therapeutical problem. Antiglaucomatous anterior cyclodiathermy is a last therapeutical option to serve the eye. PATIENTS AND METHODS: We retrospectively examined the results and the complications of 29 eyes, which were consecutively treated with anterior cyclodiathermy between 1992 and 1998. RESULTS: We found a significant decrease of the intraocular pressure (IOP) during mean follow-up of 10 month, reduction of antiglaucoma medication, no change of visual acuity and no severe complications (no phthisis bulbi, no severe intraocular hemorrhage, no sympathetic ophthalmia). CONCLUSION: Anterior cyclodiathermy is a successful treatment for selected patients with severe forms of glaucoma, if other operation techniques and antiglaucoma medication fail to decrease the IOP.

Adolescent↗
PubMed1999

"Orientation teeth" in non-mechanical laser corneal trephination for penetrating keratoplasty: 2.94 microm Er:YAG v 193 nm ArF excimer laser.

BACKGROUND/AIMS: "Orientation teeth" at the donor trephination margin and correspondent "notches" at the host margin facilitate graft orientation and avoid "horizontal torsion" induced by asymmetric suture placement. In this study the quality and reproducibility of these structures created by non-mechanical laser corneal trephination were compared using two laser emissions. METHODS: The procedure was performed in 20 enucleated pigs' eyes using open metal masks with eight "orientation teeth/notches" (0.3 x 0.15 mm, base x height), an automated globe rotation device, and either a 193 nm ArF excimer laser or a Q switched 2.94 microm Er:YAG laser. "Teeth/notches" were analysed by planimetry and scanning electron microscopy (SEM). RESULTS: Mean size was 0.30 (0.027) x 0. 16 (0.017) mm for "teeth" and 0.30 (0.035) x 0.15 (0.021) mm for "notches" (excimer), and 0.31 (0.022) x 0.16 (0.015) mm and 0.30 (0.031) x 0.14 (0.021) mm respectively (Er:YAG). Overall, variability of notches was higher than that of teeth. By SEM, comparable cut regularity and sustained ablation profile were observed with both lasers. However, the corneal surface at the cut edge appeared slightly elevated (</=35 microm) in the Er:YAG group. CONCLUSION: Orientation teeth/notches resembling those obtained with the excimer laser can be created using the Q switched Er:YAG laser, with potential advantages of lower costs, convenient equipment size, and solid state safety.

Animals↗
PubMed1999

Tumor growth of a choroidal malignant melanoma and aqueous flare. Report of a case.

We report the use of the laser flare-cell meter (LFCM) in monitoring blood-ocular barrier breakdown induced by a choroidal malignant melanoma in an 88-year-old white male, who refused enucleation or radiation treatment. During a follow-up of 16 months, aqueous flare values measured with the LFCM increased from 12.8 to 26.5 photon counts/ms with continuous tumor growth from a height of 7.9 to 18 mm. Our finding of increasing flare values with tumor growth appears to confirm the observation that aqueous flare is influenced by the size of uveal malignant melanomas. Quantification of aqueous flare with the LFCM may be helpful in the follow-up of eyes with intraocular tumors.

Aged↗
PubMed1999

Quantification of blood--aqueous barrier breakdown after trabeculectomy: pseudoexfoliation versus primary open-angle glaucoma.

PURPOSE: Impairment of the blood-aqueous barrier in unoperated eyes with pseudoexfoliation syndrome has been demonstrated by fluorescein angiography, fluorophotometry, measurement of aqueous flare, and determination of aqueous protein. We performed noninvasive quantification of aqueous flare using the laser flare-cell meter to compare blood-aqueous barrier breakdown after trabeculectomy in eyes with primary open-angle glaucoma (POAG) and in eyes with pseudoexfoliative glaucoma (PEX). METHODS: Twenty eyes with PEX and 20 eyes with POAG were included in the study. Trabeculectomy was performed by two surgeons according to a standard trabeculectomy technique. Intra- and postoperative treatments were identical in both groups. Aqueous flare was quantitatively determined using the laser flare-cell meter FC-1000 (Kowa, Tokyo, Japan) before and 3, 5, 7, and 9 days after trabeculectomy. Absolute flare and difference between post- and preoperative flare values were statistically analyzed using the Mann-Whitney U-Test for independent samples. RESULTS: Before surgery, aqueous flare values were significantly higher in PEX than in POAG. On days 3, 5, 7 and 9 after surgery, flare values were significantly higher in eyes with PEX than in eyes with POAG. Absolute differences between post- and preoperative flare values also were significantly higher in eyes with PEX, but this was not true for percentage values. CONCLUSION: These results show that substantial blood-aqueous barrier breakdown occurs in eyes with PEX after trabeculectomy. These alterations may contribute to early or late complications of trabeculectomy and indicate the need for close postoperative follow-up evaluation in eyes with PEX.

Aged↗
PubMed1998

Stromal thermal effects induced by nonmechanical (2.94-mum) erbium:YAG laser corneal trephination.

OBJECTIVE: To determine stromal thermal changes after erbium (Er):YAG laser corneal trephination with the use of 2 open masks. METHODS: Corneal trephination was performed in 89 enucleated pig eyes with an Er:YAG laser (400-microsecond pulse duration), 4 open masks (2 metallic and 2 ceramic) for both donors and recipients, and an automated globe rotation device. Different combinations of laser settings were used: pulse energy, 100, 200, and 400 mJ; repetition rate, 2 and 5 Hz; and spot size, 1.3 and 3.2 mm. Thermal effects in corneal stroma and regularity of the cut edges were quantitatively assessed by light microscopy, transmission and scanning electron microscopy. RESULTS: Best regularity and minimal thermal effects of the cut were observed with the use of ceramic masks at 200 mJ, 2 Hz, and 3.2-mm spot size, with middepth thermal changes of 18 +/- 2 microm. Effects increased with cut depth and were lower in donor corneas and with the use of ceramic masks (P<.001). Regularity of the cut was higher in the donors (P = .05) with lower repetition rates (P<.001). CONCLUSIONS: Even with the "free-running" Er:YAG laser mode, features of the trephination cut resembling those created by the 193-nm excimer laser along metal mask were achieved. Ceramic masks may be more suitable than metal masks. The Er:YAG laser seems to have the potential to be a compact and low-cost alternative in nonmechanical trephination for penetrating keratoplasty. CLINICAL RELEVANCE: Thermal effects after corneal trephination with the free-running Er:YAG laser (2.94 mm) are limited and predictable.

Animals↗
PubMed1998

[Immunologic transplant reactions after non-mechanical corneal trepanation with 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 x keratoconus, 78 x Fuchs' dystrophies, 31 x bullous keratopathies, 28 x ulcers, 25 x avascular scars, 12 x stromal dystrophies, 4 x buphthalmos, 4 x others; 202 x PK only, 84 x 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 x 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 x 7.0 to 7.5 x 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.

Adolescent↗
PubMed1998

[Results of implantation of transsclerally sutured posterior chamber lenses in combination with penetrating keratoplasty].

UNLABELLED: Implantation of transsclerally sutured posterior chamber lenses is one possibility of surgical visual rehabilitation of eyes with pseudophacic or aphacic bullous keratopathy without zonular-capsular support. We analyzed the results and complications of the surgical procedures performed in our institution. PATIENTS AND METHODS: Out of 1567 penetrating keratoplasties and 220 transsclerally sutured posterior chamber lenses that were performed at our institution between 1991 and 1996, patients that underwent penetrating keratoplasty and sutured posterior chamber lens implantation in whom sufficient clinical information was available were selected and analyzed in a retrospective, nonselective study. Surgery was performed by a total of four surgeons and included anterior vitrectomy, inside-out suturing and synechiolysis if necessary. Detailed pre- and intraoperative data, postoperative course and complications were recorded and analyzed. RESULTS: A total of 96 eyes were analyzed (patient age 17-92 years, 49 male, 46 female). Penetrating keratoplasty was performed for pseudophacic (63) oder aphacic (15) bullous keratopathy or for corneal scars following penetrating injury (18). Mean follow-up was 22 months. In 82 of 96 eyes, visual acuity improved following surgery. Complications included rhegmatogenous retinal detachment in 4 eyes, graft rejection in 5 eyes, secondary angle-closure glaucoma caused by preexisting anterior synechiae in 7 eyes, and persisting cystoid macular edema in 19 eyes. Luxation or subluxation of the IOL and endophthalmitis were not observed in any of the patients. CONCLUSION: Implantation of transsclerally sutured posterior chamber lenses appears to be a safe procedure and is considered by us to be the procedure of choice to correct aphacia during penetrating keratoplasty in eyes with absent zonular-capsular support. The majority of postoperative complications is apparently caused by preexisting problems related to previous surgery and/or trauma, such as peripheral anterior synechiae, vitreous incarceration or cystoid macular edema.

Adolescent↗
PubMed1998

Aqueous flare in retinitis pigmentosa.

BACKGROUND: The purpose of this study was to quantify blood-ocular barrier impairment by measuring aqueous flare in retinitis pigmentosa (RP) and to search for clinical correlations. METHODS: Forty-nine patients (94 eyes) with RP and 85 normal controls were examined. Aqueous flare was quantified with the noninvasive laser flare-cell meter (FC-1000, Kowa, Japan). Degrees of cystoid macular edema (CME), vitreous pigment dusting (VPD), intraretinal migration of retinal pigment epithelium, and waxy pallor of the optic nerve head were determined semiquantitatively by biomicroscopy. Data were analyzed using the t-test the Mann-Whitney U-test, the chi-squared test and regression analysis by taking into account the dependency of data from two eyes of the same patients. RESULTS: Aqueous flare (photon counts/ms) was significantly higher in RP (mean 10.11 +/- 3.53) than in normals (3.89 +/- 0.94; P < 0.001). Clinically significant CME was present in 26% of eyes with RP, being significantly more frequent in autosomal dominant RP (11 of 16 eyes, 69%) than in other variants (17%; P < 0.005). Multivariate analysis revealed that CME was most strongly associated with flare values (r = 0.84), P < 0.01), whereas--after adjusting for CME--correlations between aqueous flare and other clinical findings did not reach significance. CONCLUSION: RP eyes show increased aqueous flare values, indicating impairment of blood-occur barriers. This appears to be associated with CME and with autosomal dominant RP.

Adolescent↗