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Biomedical subjects

F Bigar

Publications and source records attributed to F Bigar.

At least 19 recordsLinked to original sources
PubMed1994

[Examination of the cornea of intact donor eyes with confocal slit-scanning video microscopy].

The specular microscopic examination of the endothelium of intact donor eyes can be rendered difficult or even impossible due to light scattering of stromal edema. We have been able to visualize large areas of the corneal endothelium of a donor eye with advanced stromal edema--stored for over 32 h. in a moist chamber--with a confocal slit-scanning video microscope. Furthermore, this optical arrangement enables the examination of very thin tissue sections with high resolution and a remarkably enhanced contrast of the corneal micromorphology (epithelial cells, Bowman's membrane, nerve fibers, keratocytes, endothelial cells).

Alcoholism↗
PubMed1992

[The unsolved problem of transplant astigmatism].

Irregularities of the trephine margins, donor/recipient thickness disparity and irregular suture technique are the important factors for high astigmatism after penetrating keratoplasty. A combined suture technique using eight interrupted 11-0 Mersilene sutures and a single continuous 10-0 nylon suture enables to control and to remedy the final postkeratoplasty astigmatism. In 35 patients with a corneal graft a final astigmatism of 2.9 diopters was reached after removal of the continuous suture and partial leaving in place of single interrupted Mersilene sutures.

Astigmatism↗
PubMed1992

Corneal transplantation.

Corneal transplantation is the most widely practiced form of clinical transplantation. This was made possible by the development of donor handling and preservation techniques, such as cooled culture media and organ-culture systems, that guarantee a sufficient supply of donor tissue. Corneal grafting is performed to improve visual function, to preserve the integrity of the eye, or to reduce pain. Patients with visual disability who present with keratoconus or dystrophy have a good prognosis for retaining a thin, transparent graft on a long-term basis. In this patient group the limiting factor for a gratifying visual outcome is high residual postkeratoplasty astigmatism, a still-too-frequent occurrence. Refinement in trephination techniques should help overcome this pitfall. Patients with vascularization or regrafting who are in the high-risk category may benefit from HLA matching or the use of cyclosporine and other immunosuppressive agents that are currently being tested in experimental models for reducing the impact of allograft rejection.

Astigmatism↗
PubMed1991

[Tyndallometry of the anterior chamber with the Kowa FC-100 Laser FLare-Cell Meter].

The laser flare-cell meter measures the scattered light intensity of a He-Ne laser in the aqueous of the anterior chamber. It allows a reliable quantitative determination of the flare and the number of cells in the aqueous humor. The aqueous flare intensities are significantly decreased by short-acting mydriatic agents such as 0.5% tropicamide and phenylephrine. Diurnal variations and an increase of the aqueous flare with increasing age were demonstrated.

Adolescent↗
PubMed1991

[Usefulness of the Laser FLare Cell Meter (LFCM, Kowa FC-1000) for evaluating inflammation of the anterior chamber in clinical practice].

The Laser Flare Cell Meter (LFCM, Kowa FC-1000), an instrument measuring aqueous flare and cells in a quantitative, objective and non-invasive way, has been mainly used so far to measure inflammation in clinical and experimental research. In the light of some illustrative examples, its practical clinical usefulness is presented; the LFCM was found to be specially helpful in 3 types of situations. 1. In acute anterior uveitis (AAU) patients, precise LFCM monitoring of inflammation made it possible to avoid excessive corticosteroid therapy, mainly by more rapid and controlled tapering at the end of an inflammatory episode, so possibly minimizing steroid side effects in a group of patients prone to numerous uveitis recurrences. In a steroid-responder patient it allowed successful treatment of a flare-up of AAU with a combination of systemic and topical diclofenac (Voltaren), a potent nonsteroidal antiinflammatory drug. 2. LFCM monitoring of inflammation in patients undergoing laser treatments allowed optimal adjustment of antiinflammatory therapy. Diclofenac drops (Voltarene Ophta), were sufficient to treat inflammation in all patients, undergoing Nd-YAG laser posterior capsulotomy or Argon laser trabeculoplasty. 3. In patients with acyclovir treated herpes simplex or herpes zoster uveitis corticosteroid treatment should be avoided whenever possible, because of the tendency to develop steroid dependency. LFCM monitoring of this group of patients gave a precise evolutionary pattern of inflammation and permitted to avoid steroid treatment in many patients.

Acyclovir↗
PubMed1990

[Astigmatism following cataract surgery: comparison following wound closure with nylon suture and Mersilene].

Mersilene (polyester fiber) is stronger and less elastic than nylon suture material. In contrast to nylon, Mersilene does not appear to be susceptible to biodegradation in the long term. After a follow-up period of 6 months, the regression of surgically induced astigmatism following extracapsular cataract extraction and lens implantation with a conventional 150 degree corneoscleral incision was in the same range with nylon monofilament 10-0 and Mersilene 10-0. With nylon single sutures (14 patients) there was a reduction from 3.5 and with Mersilene (12 patients) from 3.9 to 0.9 diopters.

Astigmatism↗
PubMed1988

[Pseudophakic bullous keratopathy].

The number of cataract extractions in Switzerland has tripled since 1981. In 1986, a total of 15,500 cataract operations were performed, 95% of which were accompanied by an intraocular lens implantation. In spite of this tremendous increase pseudophakic bullous keratopathy remains a rare indication for keratoplasties: between 1980 and 1986 only 20 grafts were performed at the authors' clinic for irreversible corneal edema following lens implantation. After implantation of posterior chamber lenses, penetrating keratoplasty for corneal decompensation is performed after a significantly shorter period (one year) than with anterior chamber lenses (three years), or in iris-supported lenses (four years). In Switzerland, the incidence of pseudophakic bullous keratopathy among patients with posterior chamber lenses is around 0.1 to 0.3%. A long-term investigation of the endothelial cell density over a period of seven years in 16 patients with a Binkhorst two-loop lens revealed a quite stable and satisfactory cell density of 1600 cells/mm2.

Adult↗
PubMed1988

[The tolerance of hydroxypropylmethylcellulose in implantation of posterior chamber lenses].

In 65 patients, the safety of a 2% solution of hydroxypropylmethylcellulose (HPMC) was investigated by comparing HPMC with a balanced salt solution during posterior chamber lens implantation. The controlled open randomized trial consisted of two groups of patients: 1) in 37 patients the surface of the implant was coated with HPMC and the inner wound sealed prior to insertion; 2) in the control group with 28 patients the lens was dipped in the balanced salt solution. There were no statistically significant differences between the two groups as regards any of the characteristics investigated, such as visual acuity, intraocular pressure, corneal thickness, endothelial cell loss, and postoperative irritation within the anterior chamber. There was no rise in mean intraocular pressure in the HPMC group on the first postoperative day, and a rise of 1 mm Hg in the control group. The increase in corneal thickness on the first postoperative day in the HPMC group was 0.07 and in the control group 0.04 mm. At re-examination (50th postoperative day) the mean thickness in both groups was identical to the initial values. The mean endothelial cell loss at re-examination was 18% (+/- 16%). No serious side effects were observed. HPMC may be regarded as a well-tolerated viscoelastic substance.

Aged↗
PubMed1987

Corneal regrafts.

Report on the clarity of 45 corneal regrafts with a minimum follow-up time of 1 year. The results of regrafts in keratoconus are good. In herpetic disease with corneal vascularization and frequent secondary glaucoma the results are poor. In patients with failed grafts for corneal dystrophies or degenerations the regrafts can be beneficial.

Corneal Transplantation↗
PubMed1984

[Old versus young donor corneas].

Postoperative thinning curves of 52 corneal grafts in keratoconus eyes show no significant difference between young and old donor material during the first 8 days. There is also no significant difference in the surgical and further postoperative endothelial cell loss up to 2 years. The examination of 23 grafts performed 17 years ago revealed an average cell density of 860 per mm2-independent of the donor age. The clinical experience that graft clarity is not related to the donor age and our present findings suggest that there is no upper age limit for corneal donor material.

Age Factors↗
PubMed1984

[Limitations of eyeglasses and contact lens care of keratoconus].

The principal criteria for the correction of keratoconus with spectacles are the upper radii values, meridian differences and the position of the apex in relation to the fixation line. Possibilities of correction with contact lenses may be limited by optical (opacities, bad peripheral image influence etc.) and fitting factors (among others increasing ectasis, major differences in the arrow height between the apex of the cone and the surrounding cornea). Some of the problems encountered hitherto can be solved with a new "smooth flat fitting" lens.

Contact Lenses↗