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Biomedical subjects

B E Frueh

Publications and source records attributed to B E Frueh.

25 records · Page 2Linked to original sources
PubMed1995

Indications, results, and complications of refractive corneal surgery with lasers.

The use of lasers to correct refractive errors has become an established clinical procedure in many countries. Excimer laser photorefractive keratectomy (PRK) has been performed on an estimated 400,000 to 500,000 eyes worldwide. For myopia up to about 6.0 D, PRK appears to be generally safe, exhibiting acceptable accuracy, predictability, and stability. Complications of PRK can occur intraoperatively, and early or late postoperatively. For higher degrees of myopia, laser in situ keratomileusis may prove to be a more appropriate procedure, but long-term follow-up is needed. Hyperopic PRK and holmium:yttrium-aluminum-garnet thermokeratoplasty are still considered investigational methods, and for newer technologies, such as solid-state lasers, human trials are being launched.

Cornea↗
PubMed1995

Endothelial cell morphology after phototherapeutic keratectomy.

The purpose of the present study was to investigate endothelial vital reactions after the performance of large central excimer laser keratectomies at various depths. Central 5 mm keratectomies were performed in porcine eyes. The ablations were carried out at depths of 0 (controls), 200, and 400 micron or until perforation occurred. One-third of the corneas were immediately stained with trypan blue and alizarin red, and two-thirds of the eyes were perfused for 1 or 6 h prior to vital staining. The numbers of endothelial cells and damaged cells were assessed. No significant difference was found between 200- and 400 microns deep keratectomies as compared with control corneas at any given time. Perforated corneas showed endothelial and stromal cell damage surrounding the perforation. We conclude that deep excimer laser keratectomies do not affect endothelial cell density and viability for up to 6 h postoperatively. Therefore, excimer laser lamellar keratoplasties appear to be a safe procedure for the underlying endothelium.

Animals↗
PubMed1995

Corneal grafting of donor tissue preserved for longer than 4 weeks in organ-culture medium.

In vitro viability of the endothelium of corneas stored in organ-culture medium is longer than in other storage techniques. This article reports on the clinical results of 20 penetrating keratoplasties performed using corneas stored for > 4 weeks in organ culture. Seventeen of the procedures were elective and three were emergencies. Mean preservation time was 35.6 +/- 7 days (mean +/- SD) and mean follow-up was 16.2 months. During preservation, an endothelial cell loss of 10% was noted. Seventeen grafts remained transparent, and three failed between 3 and 24 months postoperatively. Mean endothelial cell density was 2,153 +/- 372/mm2 at 4 months and 1,854 +/- 390/mm2 at 12 months. Central pachymetry was 548 +/- 53 microns at 4 months and 528 +/- 57 microns at 12 months after surgery. Corneas stored for up to 48 days in organ culture can be used in elective as well as in emergency procedures.

Adolescent↗
PubMed1992

11-0 mersilene as running suture for penetrating keratoplasty.

We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 +/- 2.1 diopters at six months, was 2.4 +/- 2.3 diopters at 12 months, and was 2.5 +/- 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.

Adult↗
PubMed1992

Running nylon suture dissolution after penetrating keratoplasty.

We attempted to evaluate whether the low degrees of astigmatism achieved early in the postkeratoplasty period with the combined interrupted/running suturing technique were maintained for long periods of time. For 13 to 70 months (mean, 30.2 months), we monitored a group of patients (25 eyes) who had previously undergone the combined interrupted/running suturing technique (12 interrupted 10-0 nylon sutures and one running 11-0 nylon suture). Nine running sutures broke spontaneously, causing a significant increase of the keratometric astigmatism of the entire population from 1.7 +/- 1.6 to 3.4 +/- 2.6 diopters (mean +/- standard deviation). The mean vector-corrected change in astigmatism after suture breakage was 4.9 +/- 2.6 diopters. Surgical procedures to reduce astigmatism were required in many of the eyes in which the 11-0 running nylon suture broke. Our results suggested that 11-0 nylon is not an ideal material for the running suture because its high rate of spontaneous disruption leads to undesired, statistically significant increases in postkeratoplasty astigmatism. Further, our results indicated that the selective suture technique can maintain low degrees of astigmatism only if the sutures remain intact. Studies of the effect of keratoplasty suturing techniques on astigmatism should probably include a follow-up that is sufficiently long to indicate its long-term value to the patient.

Adult↗
PubMedDate not supplied

Morphology of the stromal surface and endothelium using two different microkeratomes.

PURPOSE: To compare stromal surface and endothelial morphology after keratectomies and after laser in situ keratomileusis (LASIK), using two different microkeratomes. METHODS: Keratectomies (160-microm and 400-microm) were performed on 82 enucleated porcine eyes using the Chiron Automated Corneal Shaper (52 eyes) and the Microtech Turbokeratome (30 eyes). LASIK procedures of -9.00 D, -27.00 D, and -36.00 D were performed with a Schwind excimer laser. The corneas were immediately fixed in glutaraldehyde or stained with alizarin red and trypan. Scanning electron microscopy was then performed. RESULTS: All keratectomies performed with the Chiron microkeratome displayed a relatively smooth surface. The quality of the keratectomies with the manually advanced Microtech microkeratome was variable, with a high incidence (4 of 9) of incomplete cuts and irregular surfaces. In the eyes in which the stromal laser ablation was performed, a thin layer of condensed stroma (pseudomembrane formation) was seen. Vital staining did not indicate endothelial damage. CONCLUSIONS: The surface morphology was unacceptable for one of the microkeratomes tested. Keratectomies of 160 to 400 microm and LASIK up to -36.00 D did not acutely alter endothelial morphology in porcine eyes.

Animals↗