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Biomedical subjects

F M Polack

Publications and source records attributed to F M Polack.

At least 55 records · Page 3Linked to original sources
PubMed1977

The phacoemulsification procedure. III. Corneal complications.

Persistent corneal edema is one of the complications of phacoemulsification. Five patients underwent this procedure 6 to 8 months before keratoplasty was performed. In addition to bullous keratopathy, two corneas had corneal scarring due to probe overheating or corneal vascularization of the anterior chamber. Electron microscopy of corneal specimens showed that four cases had Fuch's dystrophy without warts and one had guttata. Endothelial cell destruction varied from lessions of small size (15 to 50 mu) to large abrasions. Cases with severe edema and vitreous adhesion showed retrocorneal membrane formation. Surgical trauma seemed to have precipitated decompensation of these dystrophic corneas.

Aged↗
PubMed1976

Corneal chromomycosis: double infection by Phialophora verrucosa (Medlar) and Cladosporium cladosporioides (Frescenius).

Phialophora verrucosa and Cladosporium cladosporioides were isolated from a corneal ulcer. The lesion had been previously treated with antivirals and steroids and did not respond to Pimaricin therapy or conjunctival flap. A penetrating keratoplasty was performed with good functional and optical results. Chromomycosis of the cornea is an unusual infection. This is the second case of Phialophora in Florida and the first case of Cladosporium infection.

Animals↗
PubMed1976

[Experimental keratoplasty after sensitization by a bacterial antigen (Streptococcus A group)].

Experimental (rabbit) penetrating keratoplasties with donor tissue sensitized to a bacterial antigen (Streptococcus Group A) were placed in normal rabbits and animals sensitized to the same antigen. Severe graft reactions developed two months after grafting in sensitized rabbits while no reaction occurred in controls. It is possible that homograft reactions can be triggered and super-imposed to the immuno-allergice reaction to the foreign antigen present in host and donor.

Animals↗
PubMed1976

The phacoemulsification procedure. I. The effect of intraocular irrigating solutions on the corneal endothelium.

Irrigating solutions for intraocular purposes were evaluated for their possible damaging effects on the corneal endothelial cell structure and function. Rabbit corneal endothelium was perfused in vitro with Tis-u-Sol, Travenol Ringer's Solution, or Travenol Sodium Chloride. The irrigating solutions caused an immediate corneal swelling of 67 mum per hour +/- 5 (mean +/- standard error), which was not modified by a previous stabilization perfusion with glutathione-bicarbonate Ringer's (GBR). In contrast, the Plasma-lyte-148 solution which is used in the phacoemulsification procedure, did not cause corneal swelling for more than twenty minutes, and for more than sixty minutes if the cornea was perfused after a GBR stabilization. After more than sixty minutes of corneal swelling, endothelial intercellular junction separations appeared. This breakdown was present with the tested irrigating solutions except for Travenol Ringer's Solution, which contained calcium. Plasma-lyte was also evaluated in conjunction with the surgical phacoemulsification procedure. The complete procedure or just irrigation with ultrasound did not cause endothelial cell damage similar to a prolonged in vitro irrigation. Instead, endothelial cells were traumatically damaged in varying degrees by the surgical manipulations.

Animals↗
PubMed1976

The phacoemulsification procedure. II. Corneal endothelial changes.

The effect of phacoemulsification, with the Cavitron-Kelman instrument, on the corneal endothelium of rabbit and cats was studied by scanning electron microscopy and nitroblue tetrazolium staining. The various steps of the procedure were examined separately. Irrigation of the anterior chamber of the eye with balanced salt solution (Plasma-Lyte) for ten minutes caused no cell damage. Ultrasound and irrigation alone for four to six minutes caused increased permeability to NBT. Edema of endothelial cells and cell junction disruption occurred after eight minutes of anterior chamber irrigation with Plasma-Lyte. Uncomplicated phacoemulsification produced moderate cellular edema with scattered loss of endothelial cells. Destruction of endothelial cells was frequent after phacoemulsification, it appeared to be due to lens nucleus manipulation in the anterior chamber, instrumentation, and needle contact. From two to five days postoperatively, intercellular edema, altered cell morphology, and mosaic pattern were seen. However, it gradually recovered and seven to ten days later the endothelium appeared normal.

Animals↗
PubMed1975

The endothelium of failed corneal grafts.

Corneal buttons of failed grafts were obtained at the time of regrafting and studied with the scanning electron microscope. The condititions studied varied from failed donor tissue to graft rejections and herpetic endothelial disease. The scanning electron microscope offers a tridimensional, panoramic high-power view of pathologic endothelium that can be correlated to the clinical picture and light or transmission electron microscopy. The endothelium of recent grafts may be damaged by organized blood clots; leukocytes were present over the graft endothelium, possibly as a normal reaction to surgery. Herpetic infection of the graft may cause death of endothelial cells and formation of granulomatous lesions, with damage to Descemet's membrane. A large detachment and rupture of Descemet's membrane was found in a case of wound dehiscense.

Cell Membrane↗
PubMed1975

Keratoplasty wound separations.

Forty cases of partial or full-thickness corneal wound separtions after penetrating keratoplasty comprised three groups. One group of separations occurred before suture removal, due to technical problems encountered at surgery or increased intraocular pressure, or both. Most separations occurred immediately after suture removal and may be the most preventable. The third group of separations occurred long after suture-removal and may not be associated with obvious trauma. About 50% of all wound separations caused graft failure, but patients with fullthickness wound separations had a worse prognosis for visual acuity recovery. Of those grafts that failed after wound separation and were retransplanted, there is a good chance of visual recovery. In our series, fullthickness wound separations or partial wound gape occurred in about 5.7% of our transplant cases. With delay of suture removal associated with a more adequate clinical means of evaluating wound healing, this number may be decreased.

Adolescent↗
PubMed1975

Detachment of Descemet's membrane from grafts following wound separation: light and scanning electron microscopic study.

Examination of 4 specimens of failed grafts following wound rupture shows that separation of Descement's membrane from the periphery of the graft in the area of dehiscence is followed by morphological changes in endotelial cells and by the development of fibrous membranes. Defective wound healing after repair is probably caused by persistent edema of graft stroma. With sudden decompression of the globe, rupture and total detachment of Descemet's membrane may occur. Changes in Descemet's membrane and eventual failure of the graft may occur mostly on the basis of anatomical changes in the endothelium of the graft and not necessarily by inflammation which was not present in these 4 specimens.

Cornea↗
PubMed1975

The corneal host-graft function. Physiopathology of the scar.

The scar of penetrating homografts was studied in experimental grafts in rabbits and monkeys. The purpose of the study was to analyze the healing process in those grafts and correlate these findings to clinical situations of abnormal graft healing. Light, transmission and scanning electron microscopy were done for morphological studies. Radioautography with tritiated thymidine and S-35 sulfate was done to study cell repopulation and ground substance development in the scar. More than 50 p. 100 of cells present in the scar came from the host and lay down circular collagen fibers in the stroma and new Descemet's material at the endothelial level. Very tight (continuous) 10-0 nylon sutures produce necrosis of the edge of the wound and delay healing. From the morphological point of view it appears that very thin scars have less tensile strength than wider scars. These usually show circular and crisscrossing collagen fibers. Radial scars induced by silk sutures or through and through placed monofilament nylon add tensile strength to the wound.

Animals↗