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Biomedical subjects

K C Swan

Publications and source records attributed to K C Swan.

At least 19 recordsLinked to original sources
PubMed1988

A technique for removal of filariasis of the anterior chamber.

We describe a useful technique for removing filaria from the anterior chamber. In the case described, an immature female filaria approximately 15 mm in length was removed from the anterior chamber of a 32-year-old man in western Oregon and identified as a species of Dipetalonema. Features of four cases of filarial infection in the anterior chamber from the same geographic area are described. In three out of four cases, the worms were removed alive without difficulty by means of simple irrigation aspiration system.

Adult↗
PubMed1983

Descemet's membrane in penetrating keratoplasties of the human eye.

The response of Descemet's membrane in penetrating keratoplasty wounds was studied by light microscopy in 23 human eyes. Although only parts of the grafted areas could be sectioned in each eye, 15 splittings, full-thickness flanges, or fragmentations of Descemet's membrane were found in ten specimens. Seven of these abnormalities resulted in incarceration of Descemet's membrane into the wound. Malapposition of the wound edges was a causative factor in two additional eyes. Six of these incarcerations produced a visible stromal wound defect. Exacting surgical apposition of the stromal edges of the graft and recipient cornea can therefore be expected to reduce, but not eliminate, these healing abnormalities. Great care must be taken in cutting the graft and removing the recipient tissue to avoid stripping the tough Descemet's membrane from the overlying softer stroma with dull instruments or overlapping cuts.

Corneal Diseases↗
PubMed1983

Accommodative esotropia long range follow-up.

Thirty-nine adult patients treated for typical (refractive) accommodative esotropia in childhood continue to have problems because they have not outgrown their hypermetropia, and the majority have not developed stable binocular vision. Their hypermetropia became maximal (median 5.7 diopters) by age 6, decreased in adolescence, and then stabilized (median 4 diopters). Thirty-eight of the 39 adults wear correcting lenses full-time. Nearly all depend on relaxed accommodation to maintain alignment when they remove their glasses. Ten patients, all of whom received treatment before a constant esotropia developed are essentially orthophoric with glasses and have normal binocular vision. The remainder have small-angle deviations with glasses, 14 with varying degrees of amblyopia and peripheral fusion and 15 with anomalous correspondence and suppression. As adults, only one patient with normal binocular function has required surgery whereas 13 of the patients lacking normal fusion have had surgery for increasing esotropia, postoperative exotropia, or consecutive exotropia.

Accommodation, Ocular↗
PubMed1982

Bowman's layer in penetrating keratoplasties of the human eye.

Light microscopy disclosed ten examples of Bowman's layer incarcerations into the stromal wound in nine of 23 penetrating keratoplasty globes obtained either after death or by enucleation. Two cases involved separation of Bowman's layer from the underlying stroma. In the others, this layer remained attached to its stroma, and incarceration resulted from either fragmentation or malapposition of wound edges. Six of the incarcerations produced wound defects, and, of these three were associated with epithelial growth into the wound. These properties of Bowman's layer must be considered in the repair of corneal lacerations as well as in the performance of penetrating keratoplasties and epikeratophakia.

Cornea↗
PubMed1982

Full-thickness lamellar keratoplasty. A histologic study in human eyes.

Four human eyes, obtained 38 days to 5 years after full-thickness lamellar keratoplasty, were studied by light microscopy for evidence of fibroblast proliferation and collagen formation between the donor Descemet's membrane and the recipient stromal bed. There was delayed healing in the membrane to stroma interface, but at the graft margins a relatively normal stroma-to-stroma healing response was evident. Even in the five-year specimen, bridging of recipient collagen to donor Descemet's membrane was noted only where it was associated with subgraft vascularization. All donor endothelium had disappeared. These studies indicate that in human eyes, retention of Descemet's membrane results in a weaker total graft-host bond than provided by conventional lamellar keratoplasty. In addition, this altered healing may predispose to pseudoanterior chambers that may decrease visual acuity and diminish the theoretical optical advantages of a smooth Descemet's membrane in the graft host interface.

Adolescent↗
PubMed1979

Retrocorneal pigment proliferation after cataract extraction.

Retrocorneal pigment proliferation after cateract extraction is not rare. Downgrowths proliferate from fragments of iris pigment or peripheral iris in the corneal wound edges and occur slowly. Vision is affected if the central cornea is involved. Preventive measures include minimizing iris trauma and irrigating pigment fragments from the cornea and incision during surgery. In the study presented, patches of dislodged iris pigment epithelium were observed in 22 eyes. Lace-like downgrowths occurred in 18 eyes of 14 patients.

Adult↗
PubMed1978

Late wound separation after cataract extraction.

Many years after cataract extraction, blunt trauma ruptured limbal wounds in five eyes. Filtrations followed minor trauma in three patients, and occurred spontaneously in two others. Limbal wounds do not regain the tensile strength of adjacent normal stroma and may be further weakened by tissue incarcerations, vascularization, and other defects. Histologic studies after cataract extraction also reveal minimal collagen bridging of the stromal wound in some human eyes. Diagnosis and clinical significance are discussed.

Aged↗
PubMed1976

Pseudotendons after extraocular muscle surgery.

Following recession of a rectus muscle, a band of connective tissue designated as a pseudotendon may form between the recessed muscle tendon and the former insertion. The cut edges of the episclera at the former insertion and the sheath of the recessed muscle seem to be the primary sources of this vascularized connective tissue which replaces the avascular episclera which normally underlies the muscles. Repeated operations, excessive inflammatory reaction, injury to the sheath and intermingling of the conjunctiva and deeper wounds are predisposing factors. Pseudotendon formation does not reduce the effectiveness of a recession, because simple excision has little effect on the alignment of the eyes. Sometimes a well-formed pseudotendon can be used as a tendon to achieve additional recession of a previously recessed insertion.

Animals↗
PubMed1975

High altitude retinopathy in mountain climbers.

Retinal hemorrhages appear to be a frequent, though often unappreciated, occurrence in unacclimated climbers experiencing prolonged exposure to altitudes above approximately 3,658 meters (12,000 ft), heights frequently attained by American moutaineers. This condition has not received attention in the ophthalmologic literature, though several reports of retinal and vitreous hemorrhages have appeared in nonophthalmologic journals. Of six surviving members of a climbing expedition of Mt. Aconcagua, four had retinal hemorrhages. Two had permanently disturbed vision with paracentral scotomas plotted on a tangent screen.

Adult↗
PubMed1975

Unintentional filtration after cataract surgery.

The eyes of an 81-year-old man were obtained three and ten days after intracapsular extractions had been made through limbal incisions under limbal-based flaps of conjunctiva and Tenon's capsule. The wounds were closed with 7-0 chromic collagen. Before death from bronchopneumonia, the patient developed bilateral filtrations in association with violent coughing spells. In both specimens, the healing processes of the conjunctiva and Tenon's capsule were advanced, confining the escaping aqueous humor to the subepithelial tissues of the flap. In contrast, the stromal wounds were still inert in accordance with our earlier observations that these wounds are precariously weak during the first two weeks after surgery. In cataract surgery, flaps including both conjunctiva and Tenon's capsule should be prepared and closed to support the slower healing stromal wound. Prevention of filtrations is not a simple matter of using many sutures. This patient's eyes demonstrated that improperly placed or too tightly tied sutures may be directly responsible for leaking wounds.

Aged↗