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Biomedical subjects

N Ehlers

Publications and source records attributed to N Ehlers.

At least 55 records · Page 3Linked to original sources
PubMed1995

Healing velocity of corneal epithelium evaluated by computer. The effect of topical steroid.

To objective determine the area of corneal abrasion, a video camera was connected to a slit-lamp. The videosignal was digitized and analyzed by a computer program. The maximal horizontal and vertical diameters were measured as well as the total abraded area. The algorithms of calculating healing velocity of corneal epithelium are discussed, and this system was tested on patients treated for myopia with a 193 nm ArF excimer laser. It was shown that topical steroid application did not impair corneal epithelial healing velocity.

Administration, Topical↗
PubMed1995

A three-dimensional study of the human corneal keratocyte density.

The population of stromal keratocytes represents a rarely examined topic. In the present paper we investigated the three-dimensional distribution of keratocytes in human donor corneas. The keratocyte density was calculated from biochemical measurements of the DNA content in samples of the corneal (and scleral) stroma obtained from well-defined regions. The DNA content of the central stroma (0-2 mm from apex) had a mean (+/- SD) of 1.25 +/- 0.30 micrograms DNA/mg dry tissue weight, corresponding to a cellularity of 4.6 +/- 1.1 x 10(4) cells/mm3 (n = 13). Towards the corneal periphery, the cellularity gradually increased to a 60-70% higher cell density at limbus. In the central stroma, an anterior-posterior cell gradient was found with a 30% lower cellularity in the subendothelial region compared to the subepithelial stroma (n = 8). In the four main quadrants of the central stroma, a uniform cell density was found while the peripheral areas showed a 10% higher cellularity in the superior quadrant. A close intraindividual correlation was observed between data obtained from 40 paired corneas ('cornea 1' versus 'cornea 2'); the stromal cellularity within 0-3.75 mm from apex (r = 0.81), the stromal cellularity within 3.75-5.5 mm (r = 0.92), the stromal cellularity within 5.5-8.0 mm (r = 0.85), and the endothelial cell density (r = 0.84). However, within a given cornea no correlation was found between the density of endothelial cells and keratocytes. These data define normal values for the regional density of keratocytes in the human cornea.

Adult↗
PubMed1994

[Excimer laser therapy of recurrent corneal erosions].

Recurrent corneal erosions have been recognized as a clinical problem for many years. Many patients with erosions do not respond satisfactorily to the standard treatment. In this paper we present a study of treatment of 24 patients with recurrent corneal erosions with the excimer laser, where 75% of the patients reported the treatment as a success.

Adult↗
PubMed1994

Corneal storage and complications related to grafting.

This review covers the literature during the past year and follows up results published on corneal storage techniques and complications related to corneal grafting. It considers the recent progress and suggests new perspectives on the reconstituted or renovated human donor cornea. It might be possible to revive postmortem donor corneas with new cells, eg, epithelial, endothelial, or keratocytes, drawn from the future recipient or eventually with transgenetic multidonor cells. The future holds promise for the development of a new concept in corneal banking, where we leave the period of conservation and enter the era of donor cornea production.

Cornea↗
PubMed1994

Histopathological findings in failed human epikeratophakia lenticules.

Six human epikeratophakia lenticules were removed 1 to 23 months after refractive keratoplasty for aphakia (n = 2) and myopia (n = 4). The myopic group included one epi-lenticule treated with ArF-excimer laser for hyperopia. Reasons for removal were epithelial defect (n = 4), edema of host cornea (n = 1), and overcorrection (n = 1). The epi-lenticule stroma showed centrally a regular fibrillar structure with a low keratocyte density. Electron microscopy (n = 1) revealed preserved cytoplasmic organelles and nuclear appearance. Mononuclear cells were absent. Polysaccharide was demonstrated in the stroma. Bowman's layer was normal without breaks. The epithelium had variable thickness. In the peripheral wound region stromal and epithelial irregularities were evident.

Adult↗
PubMed1994

The keratocyte density of human donor corneas.

The cellularity of the human corneal stroma has not been described in the literature. In the present study we calculated the density of keratocytes in human donor corneas using a new method for biochemical measurement of the stromal DNA content (sDNA). The DNA measurements were compared to morphological counts of the number of keratocyte nuclei per area (KNPA) obtained from histological sections. A significant correlation was found between the data achieved by the two methods (r = +0.52, p < 0.001, n = 46). No significant change in either sDNA or KNPA was found during 28 days of organ culture, and no influence of donor age, sex, or post mortem time was found on either sDNA or KNPA. Both sDNA and KNPA approximated a normal distribution with a mean sDNA of 1.10 +/- 0.25 micrograms DNA/mg dry tissue weight and an average KNPA of 200 +/- 53 nuclei/mm2 (n = 35). Between paired corneas the sDNA were closely correlated (r = +0.83, p < 0.005, n = 11 pairs) with an intra-individual variation of only 0.5%. Using the sDNA data, the keratocyte density in the central region of human donor corneas was calculated to be 129,000 +/- 29.000 per mg dry tissue weight (n = 35). Thus, when corneal grafting is performed (using a 7 mm trephine) an average of 818,000 +/- 186,000 donor keratocytes are transplanted. Assuming a uniform cellularity throughout the stroma, the average number of keratocytes was calculated to be 2,430.000 +/- 551,000 per human donor cornea.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Differential diagnosis between granular corneal dystrophy Groenouw type I and paraproteinemic crystalline keratopathy.

A case of corneal opacities in a leukemic patient with an M-component in the serum proteins is presented, and a comparison is made to patients with granular corneal dystrophy Groenouw type I. The corneal deposits associated with the two conditions may appear identical with slit-lamp biomicroscopy. Granular dystrophy patients, however, show a normal serum immunoglobulin pattern in contrast to patients with paraproteinemic crystalline keratopathy. The two entities can therefore be distinguished from each other by a serum electrophoresis.

Cornea↗
PubMed1993

Long-term results with organ cultured, cryopreserved human corneal grafts. Re-examination of 17 patients.

Seventeen organ cultured cryopreserved corneas were grafted in 1978-79. When published in 1982, 12 of the grafts (71%) were clear with an average thickness of 0.51 mm and an endothelial density of 1028 cells/mm2. A re-examination of these patients after 13 years is presented. Seven grafts (58%) were clear. Average CCT was 0.51 mm and endothelial cell density was 988 cells/mm2. Visual acuity was 0.4 or better. The morphology resembled that seen after 1 year with large, multinucleated cells. It is concluded that cryopreserved grafts show a fair long-term survival. Cryopreservation may still present a possibility in the establishment of a corneal bank with the perspective of supplying histocompatible donor material.

Adolescent↗
PubMed1993

The effect of topical steroid on postoperative corneal edema and endothelial cell loss after intracapsular cataract extraction.

In a prospective study of 89 patients the postoperative corneal edema and endothelial cell count was studied after cataract extraction. A double blind investigation was performed as the patients during the first 6 postoperative days were treated with three different types of eye-drops: Maxidex, Pred-Forte 1% or placebo, all containing Benzalkonium Chloride 0.004%. The content of steroid in Maxidex and Pred-Forte was equivalent. We found no significant difference in estimates of endothelial cells in the three groups postoperatively. Corneal edema was less in the two groups treated with steroid. There was no significant difference between the two postoperative groups (p > 0.05) treated with Maxidex and Pred-Forte. The group treated with Pred-Forte showed significantly less postoperative corneal edema, calculated as the graphical area represented by the increase of central corneal thickness (CCT) after operation.

Administration, Topical↗
PubMed1992

Excimer laser treatment of pterygium.

Primary experience with the use of excimer laser in pterygium therapy is presented. Twenty-two pterygia (11 primary and 11 recurrent) were surgically removed using the bare-sclera technique followed by excimer laser ablation to smooth the corneal surface. As recurrence was observed in 20 eyes (91%) during the first year, supplementary excimer laser treatment of a pterygium does not seem to reduce the recurrence rate. The high recurrence rate in this series may to a certain extent reflect the surgical technique used (bare-sclera).

Adult↗
PubMed1992

Excimer laser refractive keratectomy for high myopia. 6-month follow-up of patients treated bilaterally.

Both eyes of twenty patients were treated for myopia with refractive keratectomy using an excimer laser (193 nm), and followed for six months. The 40 eyes were divided into Group I (22 eyes) with an attempted refraction change of 5-8 diopters; and Group I (18 eyes) with 9-12 diopters of attempted refraction change. In Group I the corrected visual acuity improved or was unchanged in 16/22 eyes. Two eyes with high preoperative corrected visual acuity had experienced a significant loss in corrected visual acuity after 6 months. In Group II, the corrected visual acuity decreased in 10/18 eyes, in 4 eyes significantly. Among the 40 eyes, 39 had a refraction change less than intended after 6 months. Overcorrection was seen in only 1 eye. In Group I, 20/22 eyes were corrected up to 2.5 diopters less than attempted. In Group II, 9/18 eyes were more than 2.5 diopters from the attempted correction. All eyes developed subepithelial opacification ('haze'), which, in spite of steroid treatment, was still present after 6 months. The haze was more severe in eyes treated with 9-12 diopters of attempted refraction change. The achieved refraction change in the two eyes of the same patient was found to be correlated, possibly due to an individual factor in corneal wound healing.

Adolescent↗
PubMed1991

Epikeratophakia for high myopia.

A cryo-technique for production of corneal epi-lenses has been developed. During the manufacturing procedure the anterior surface of the tissue is moulded and the posterior surface cut with a microtome. After cutting, the epi-lenses are stored for days to weeks in an organ culture medium. Twelve eyes in 10 patients have been treated with epikeratophakia for high myopia (greater than -7 D). In all eyes, epithelialization was complete within one week, and at follow-up 3-18 months after the operation all epi-lenses were clear. The average refractive change in spherical equivalents was 9.7 +/- 4.4 D. All eyes obtained better uncorrected visual acuity, and no eyes lost more than one line of the best corrected visual acuity. At the time of follow-up, the patients' native cornea had regained normal hydration, whereas the epi-lenses did not thin as much as expected.

Adult↗
PubMed1991

HLA-DR/RFLP compatible corneal grafts.

Fifty-one elective high risk transplantations were matched according to HLA/DR antigens and RFLP-subtypes. The 18 months survival of the grafts are 93% in the matched group compared to 50% in a non-matched compatible historical control group.

Adolescent↗