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At least 19 recordsLinked to original sources
PubMed1985

[Corneal trephining for penetrating keratoplasty: study of the degree of precision and presentation of a new trephine].

The accuracy of corneal trephination with a Franceschetti trephine was investigated on Duragel contact lenses. A modified 7.3 mm Crock trephine (Brit. J. Ophthal. 62 [1978] 74-80) with a rotating diamond blade fitted was compared with the above-mentioned method. Trephination of Duragel lenses from the convex side yielded diameters either larger or smaller than 7 mm. With one exception trephination from the concave side produced disks smaller than 7 mm. All Duragel disks had an elliptical configuration after trephination with the Franceschetti trephine. Trephination with the modified Crock trephine yielded disks with diameters close to 7.3 mm in all meridians.

Corneal Transplantation↗
PubMed1988

Configuration of corneal trephine opening using five different trephines in human donor eyes.

In this laboratory study, we used five different corneal trephines on 60 fresh human donor eyes with controlled intraocular pressure to study the variation in the size and shape of the trephine openings. With all trephines, the average diameter of the button was larger than the diameter of the trephine at the epithelial side (mean difference, 0.21 mm; range, 0.06 to 0.35 mm) and the endothelial side (mean difference, 0.42 mm; range, 0.13 to 0.79 mm), presumably because the corneal tissue protruded into the trephine during cutting. The trephines that produced the most uniform opening were a nondisposable suction trephine and a freestanding disposable blade, but they caused some undercutting.

Aphakia↗
PubMed1987

An experimental comparison of three methods for trephination of the cornea and the consequent variations in the configurations of the trephine openings.

We used the pig eye as an experimental model. The corneas of 51 whole eyes were trephined in a laboratory setting, using three different techniques to compare the variations in the trephine openings. Since it is difficult to assess the diameter of the hole created by trephination, we measured both the epithelial and endothelial diameters, as well as the angle between the epithelial surface and the cut of the excised corneal button, since these dimensions reflect the true shape of the hole. Trephination with either a free-standing trephine blade without a handle or with a motor-driven instrument gave the same results. However, our findings showed that the results obtained using a trephine in a holder--as is commonly used in clinical practice--were statistically significantly inferior.

Animals↗
PubMed1987

Distribution of IgA1 and IgA2 subclasses in normal bone marrow trephines and in trephines infiltrated by IgA producing multiple myeloma.

A series of 20 bone marrow trephines biopsy and necropsy specimens were strained for IgA1 and IgA2 activity, together with total IgA, by means of an indirect immunoperoxidase technique using murine monoclonal antibodies applied to paraffin sections. The specimens showed normal histology and had been taken from patients not known to be suffering from haematological or related systemic disease. The IgA1, IgA2, and total IgA containing cells were counted and expressed as a percentage of all nucleate cells in the marrow cavities. Remarkably constant percentages of and ratios between these cell types were found. The same was true for a further 10 trephines taken from patients undergoing staging procedures for epithelial malignancies, where the marrow histology was normal. The pooled mean percentage of IgA1 containing cells from both groups was 1.18% of all cells, that for IgA2 containing cells 0.18%, and for total IgA positive cells 1.41%. In addition, 12 trephines containing known IgA producing myeloma were examined. Of these, 11 contained IgA1, the remainder contained IgA2 subclass.

Adolescent↗
PubMed1992

Audit of bone marrow trephines.

AIMS: To establish criteria of adequacy for bone marrow trephine biopsy specimens and to audit the quality of trephines performed at the Christie Hospital, Manchester. METHODS: Trephines (n = 767) performed over 12 months were reviewed. Their lengths, and the lengths of their constituent parts (soft tissue, cortex, crushed marrow and interpretable marrow) were measured. The mean performance of each operator was calculated. Criteria of adequacy were established by a review of the published findings and an analysis of the relation between trephine length and the rate of infiltration by tumour. RESULTS: Before processing, the average trephine was 1.59 cm long. Trephines shrunk by 25% during processing. In histological sections the average length was 1.15 cm, consisting of 0.09 cm of soft tissue, 0.04 cm of cortex, 0.26 cm of disrupted marrow and 0.74 cm of interpretable marrow. A large number of operators were taking trephine biopsy specimens and their performance varied considerably. Review of the published findings suggested that the minimum adequate length is in the range 1.5 cm to 2.0 cm. The analysis of the relation between length of trephine and the rate of positivity for neoplasia yielded a minimum adequate length of 1.2 cm in section (1.6 cm before processing). Fifty eight per cent of the trephines were inadequate by this criterion. There was a tendency for the Jamshidi needle to produce a longer trephine than the Islam needle. CONCLUSION: According to objective criteria, at the Christie Hospital, many operators are producing a high proportion of inadequate bone marrow trephines.

Biopsy, Needle↗
PubMed1989

Preclinical evaluation of a new donor corneal trephination system.

A new corneal trephination system developed by the University of Minnesota, Department of Ophthalmology and Vision Care/3M features a corneal holder that orients and stabilizes the donor cornea during storage, transportation, and trephination. A gravity corneal punch, and disposable trephine and cutting block minimize corneal button irregularities that in other devices may contribute to postoperative astigmatism. This new system was compared with the Iowa Press by evaluating trephinated corneas on the basis of profile projectors. Buttons trephined from 10 pairs of human corneas stored in (CSM) preservation solution at 4 degrees C were evaluated by measuring diameters and edge angles and correlating them with the trephine size used. In contrast with the Iowa Press, this new system produces corneal buttons that are consistently circular, parallel-edged, and identical in size to the trephine used.

Analysis of Variance↗
PubMedDate not supplied

The theoretical effect of trephine tilt on postkeratoplasty astigmatism.

Most corneal surgeons use a free-hand technique to perform trephination. Of the factors thought to be associated with postkeratoplasty astigmatism, surgeons agree that the process of trephination has the greatest effect on astigmatism. We describe the use of a new trephine that, while affixed to the donor and/or recipient by suction, applanates the cornea to eliminate the oblique incision and undercutting that occur with currently available suction trephines. By mathematical analysis we demonstrate that a 5 degrees to 10 degrees tilt of the trephine can induce significant astigmatism. In theory, the use of the guided trephine system described here will eliminate this complication. This new instrument should be capable of producing identical incisions in the donor and recipient, thereby allowing easier wound coaptation with sutures. This new technology has the potential to eliminate trephination errors as a major cause of postkeratoplasty astigmatism.

Astigmatism↗
PubMed1988

Excimer laser trephination in penetrating keratoplasty. Morphologic features and wound healing.

The imprecision of trephination of donor and recipient corneas is a major factor in post-keratoplasty astigmatism. In order to improve the quality of trephination, the authors developed a rotating slit delivery system for noncontact penetrating keratoplasty trephination using the excimer laser at 193 nm. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and light microscopy (LM) demonstrated the superior quality of excimer-cut buttons and recipient beds as compared with those obtained by free hand and suction trephines in human cadaver and rabbit eyes. The laser trephined more regularly and precisely without distortion of corneal topography and with less damage to adjacent corneal tissue. The authors morphologically examined wound healing at 6 hours, 12 hours, 3 days, 5 days, 2 weeks, 2 months, and 3 months after penetrating keratoplasty with laser and mechanical trephination in an animal autograft model. The laser did not cause any adverse alteration of wound healing processes including cellular migration, proliferation, and production of new tissue.

Animals↗
PubMed1989

Effect of recipient-donor trephine size disparity on refractive error in keratoconus.

A retrospective study was performed to evaluate the effect of recipient-donor trephine disparity on refractive error and corneal curvature post-suture removal in keratoconus. A double running suture technique was used and donor corneas were trephined from the endothelial side. When keratoconus patients with 0.25-mm larger donor than recipient trephines were compared with keratoconus patients with the same size recipient and donor trephines, a statistically significant increase in the mean keratometer value (45.4 and 43.8 diopters [D], respectively; P = 0.03) and increase in myopic spherical equivalent (-3.5 and -1.8 D, respectively; P = 0.03) was found. When keratoconus patients were compared with phakic Fuchs' dystrophy patients (both groups had 0.25-mm oversize donor trephines), the keratoconus group had a statistically significantly higher myopic spherical equivalent (-3.5 and -1.4 D, respectively; P = 0.03) despite only a 0.7-D difference in mean keratometer value which was not statistically significant (45.4 and 44.7 D, respectively). This study supports the hypothesis that the degree of post-penetrating keratoplasty myopia in patients with keratoconus can be decreased by reducing recipient-donor trephine disparity.

Corneal Dystrophies, Hereditary↗
PubMed1983

Detection of bone marrow invasion by neuroblastoma is improved by sampling at two sites with both aspirates and trephine biopsies.

Two hundred and eight serial bone marrow samples from 49 consecutively diagnosed children with neuroblastoma were studied retrospectively for evidence of tumour invasion. Bone marrow involvement was found in 24 patients at diagnosis and in four more at a later stage in their disease. Trephine biopsies were more effective than aspirates for tumour detection in 20% of the 154 paired aspirate/trephine procedures, whilst the reverse was the case in 7%. Imprints of trephines gave no additional information. Bilateral sampling (aspirates and trephines) improved the tumour detection rate by 10% over that attained by sampling a single site. There was some correlation between specific appearances in aspirate and in trephine samples, for example the hypocellular smear and the trephine biopsy showing much stromal reaction to tumour infiltration. Bilateral iliac crest bone marrow aspirates and trephine biopsies are indicated in children with neuroblastoma, both for initial staging and for monitoring of progress.

Biopsy↗
PubMed1992

Use of paraffin wax embedded bone marrow trephine biopsy specimens as a source of archival DNA.

AIMS: To evaluate the use of DNA extracted from paraffin wax embedded trephine biopsy specimens as a source of archival nucleic acid for Southern hybridisation studies and polymerase chain reaction (PCR) amplification. METHODS: DNA was extracted simultaneously from paraffin wax embedded bone marrow trephine and lymph node biopsy specimens after incubation of tissue sections for one to five days in lysis mix and proteinase K with periodic sampling. DNA from 10 trephine biopsy specimens was subjected to PCR amplification using HLA-DPB primers to determine whether the extracted nucleic acid was of sufficient quality to permit amplification. RESULTS: For most specimens the greatest yield of high molecular weight DNA was seen after five days' incubation. Unlike lymph node material the quality of extracted nucleic acid and the quantity obtained from trephines was insufficient for Southern blot analysis. PCR amplification using HLA-DPB primers yielded positive results in six out of 10 trephine biopsy specimens. CONCLUSIONS: DNA extracted from paraffin wax embedded trephine biopsy specimens is largely degraded and unsuitable for Southern analysis but serves as a useful source of archival nucleic acid for PCR amplification.

Biopsy↗
PubMed1978

Trephination of donor corneal buttons: a scanning electron microscopic study.

Corneal buttons were cut from cat and human donor eyes by anterior trephination (with or without scissor completion) and from excised corneoscleral rims by posterior trephination (with or without a press). Scanning electron microscopy was used to evaluate the slope and quality of the cut edge, the diameter of the section of Descemet's membrane that was actually cut, and the loss of endothelial cells around the cut edge. With anterior trephination, the diameter of the section of Descemet's membrane that is cut was found to be less than that of the trephine because the cut edge slopes inward. Posterior trephination with or without a press consistently produced circular buttons with accurately cut outward-sloping edges. This resulted in a diameter of Descemet's membrane which was greater than in the anteriorly trephinated buttons. There also was less damage to peripheral Descemet's membrane and endothelium with the posterior method, especially when compared to scissor cut buttons. A 360 degree peripheral ring of Descemet's membrnae (0.05 to 0.28 mm in width) was denuded of endothelial cells with all techniques.

Animals↗
PubMed1978

[Comparative studies with scanning electron microscope on the quality of corneal disk incision using various corneal trephine (author's transl)].

The cut surface of corneal stroma from rabbits was studied with a scanning-electron microscope and compared after using a manual trephine, a motor-driven rotor trephine and a rotor trephine with mechanical guidance. It became evident that the cut surface obtained with the motor-driven trephine is clearly smoother than that obtained with manual trephine. A further improvement in the quality of the cut is evident with a mechanically guided trephine.

Animals↗
PubMed1988

Bovine bone morphogenetic protein (bBMP) induced repair of skull trephine defects in sheep.

An aggregate of partially purified bovine bone morphogenetic protein (bBMP) and bone matrix insoluble noncollagenous proteins (iNCP), weighing a total of 100 mg of lyophilized BMP/iNCP, was implanted using ultra thin gelatin capsules in skull trephine defects in adult sheep. One hundred milligram samples of freeze-dried bovine serum albumin (BSA) were similarly implanted for controls. In five sheep, the capsules were implanted in 18-20 mm trephine skull defects and also in posterior cervical muscle pouches for heterotopic controls. In two out of five sheep, the trephines were repaired with bone as early as four weeks after the operation. Eight to 12 weeks after surgery repair was complete in the other three sheep. In the control contralateral trephines, one-third to one-half of the defect was incompletely repaired. Neither the BMP nor the BSA control implants induced bone formation in the muscle. While the BMP/iNCP prepared from bovine bone consistently induced regeneration in skull trephine defects, only fibrous tissue and no extraskeletal bone was induced to form in cervical muscle pouches in sheep.

Animals↗