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J K Deg

Publications and source records attributed to J K Deg.

18 recordsLinked to original sources
PubMed1988

Histopathology and clinical behavior of polysulfone intracorneal implants in the baboon model. Polysulfone lens implants.

The authors performed 13 myopic intracorneal polysulfone implants in a baboon model using two different implant designs. In the initial series, they used eight lenticules 5 to 6 mm in diameter with a central thickness greater than 0.15 mm. These failed 6 days to 6 months after surgery. The second series of five implants 4 to 5 mm in diameter with a thinner central thickness and improved edge design was better tolerated initially, but only two of five corneas remained clear 27 months after surgery. Clinical failure was associated with corneal neovascularization and opacification posterior to the implant or aseptic necrosis of the cornea overlying the implant. In most eyes, the anterior stroma was hypocellular anterior to the implant. Numerous vacuolated keratocytes and scattered eosinophils were detected posterior to the implant. In one case, lipid deposition was confirmed posterior to the lenticule. The authors conclude that solid polysulfone intrastromal implants are not biocompatible with the baboon cornea.

Animals↗
PubMed1987

An ultrastructural and histochemical study of long-term wound healing after radial keratotomy.

Using correlative microscopy and plant lectins conjugated to fluorescent dyes, we studied two human corneal specimens obtained 66 and 70 months after radial keratotomy. In one case a second radial keratotomy had been performed 11 months before we obtained the corneal specimen, which allowed us to compare wounds 11 and 66 months old in the same specimen. The 11-month-old incisions demonstrated morphologic features consistent with incomplete wound healing, whereas the incisions examined 66 and 70 months postoperatively demonstrated complete wound healing. A different lectin binding pattern of wheat germ agglutinin and concanavalin-A was observed in the 11-month-old wounds, compared with the 66-month-old wounds. Published and unpublished morphologic studies of 17 human keratotomy specimens have demonstrated incomplete wound healing up to 47 months postoperatively. The present study documents complete corneal wound healing 66 months after radial keratotomy.

Adult↗
PubMed1987

Calcific band keratopathy after intraocular chondroitin sulfate.

A patient developed an acute onset of pseudophakic bullous keratopathy and a diffuse, gray, subepithelial corneal deposit ten days following surgery during which sodium chondroitin sulfate was used. The deposit, identified histologically as calcium, was noted throughout Bowman's layer. The absence of chronic pathologic features in the posterior cornea eliminated Fuchs' endothelial dystrophy as the cause of the acute corneal decompensation. This histopathologic confirmation of calcium deposition with one formulation of chondroitin sulfate, combined with similar conclusions from previous case reports, stimulated the reformulation of the product, which has been shown to be useful in clinical practice.

Aged↗
PubMed1987

Wound healing after astigmatic keratotomy in human eyes.

The authors analyzed three full-thickness corneal buttons and two corneal scleral rims obtained 5 1/2 to 44 months after three trapezoidal keratotomies (Ruiz), one "L," and one "TL" procedure. The indications for the penetrating keratoplasty were photophobia, corneal edema, and loss of best-corrected vision after the astigmatic keratotomy procedures. Epithelial plugs were seen in all five specimens. Complete basal lamina lined the wounds in two cases. Tangential incisions of the Ruiz procedure were shallower and demonstrated more advanced wound healing than the corresponding semiradial incisions. Two of the three Ruiz procedures demonstrated peripheral separation of the semiradial incisions. Wound healing events after astigmatic keratotomy procedures appear similar to those reported previously after standard radial keratotomy with the exception that tangential incisions appear to heal faster than the semiradial incisions.

Adult↗
PubMed1986

Electron microscopic features of never-worn soft contact lenses: deposits or artifacts?

Since scanning electron microscopy (SEM) is commonly used to evaluate hydrophilic lens deposits, it is important to know what artifacts are induced by the various techniques used to process the lenses. We performed scanning electron microscopy (SEM) using never-worn lenses with hydrations from 38.6% to 71%. Each lens was taken from its vial of factory-sealed, sterile-preserved saline and processed for SEM examination using liquid CO2, freon critical point drying, or air drying with or without alcohol dehydration. The lenses revealed abnormal surface structures occasionally resembling deposits reported on worn soft contact lenses. Varying degrees of gas pockets and surface wrinkling were seen. Individual polymers and lens hydration reacted differently to the various techniques of processing. Of the four methods evaluated, air drying without alcohol dehydration induced the least artifacts.

Contact Lenses, Hydrophilic↗
PubMed1986

Growth characteristics of primate (baboon) corneal endothelium in vitro.

Primate (baboon) corneal endothelial cells have been grown continuously in vitro for over 40 passages. Endothelial cells migrated from the explants within three to five days. Growth became confluent by 14 to 21 days; the cells in culture were polygonal in shape and formed a compact monolayer. In passages one to four, cells divided with a doubling time of 72 hours; this increased to 96 hours after the 16th passage. Even though the general morphological appearance was unchanged in passages greater than 10, the cells became irregular, exhibiting an enlarged and elongated profile. The addition of epidermal growth factor to the medium resulted in increased cell growth. Cultured cells were successfully transplanted onto Descemet's membrane of de-endothelialized baboon corneas. This study demonstrates that primate corneal endothelial cells can be grown continuously in tissue culture and subsequently transplanted in vitro.

Animals↗
PubMed1985

Delayed corneal wound healing following radial keratotomy.

Four human corneal specimens obtained 5 to 47 months following radial keratotomy were evaluated by correlative microscopy. Repeat radial keratotomies had been performed in two cases. We documented gaping keratotomy incisions, epithelial plugs, and epithelial-lined incisions. In all cases, Bowman's layer was malapposed with slight to moderate fibroblastic activity at the incision sites. Epithelial and endothelial radial ridges were seen in two cases. No endothelial damage was seen under the radial incisions. The morphological evaluation of these specimens show the potential for a poor wound-healing response when corneas with previous corneal surgery and/or pathologic states undergo radial keratotomy.

Adult↗
PubMed1984

Refractive keratoplasty. Keratophakia in a nonhuman primate.

We performed 11 keratophakia procedures in a baboon (Papio cynocephalus) model using the same instruments and techniques that are presently clinically employed. We requested 10 diopters of correction in nine cases and 14 D in two cases. We were able to achieve a mean (+/- SD) keratometric steepening correction of 5.8 +/- 1.5 D using fresh and 9.3 +/- 5.0 D using prefrozen donor corneas. The overall change was 8.0 +/- 4.3 D. Morphologic results and corneal clarity were consistent with the excellent clinical results. The keratophakia lenticles were sparsely repopulated with keratocytes up to six months following surgery, but at 12 months, partial keratocyte repopulation of one lenticle did occur. We recommend that the baboon model be used for evaluation of all lamellar refractive surgical procedures.

Animals↗
PubMed1984

Alloplastic implants for the correction of refractive errors.

Convex-shaped, hydrophilic lenticles of various water content were implanted into microkeratome-dissected corneal pockets in a baboon model. Freshly trephined, cryolathed, and factory-lathed hydrogels were evaluated for periods exceeding 15 months, documenting clinical response, corneal curvature shifts, and morphologic features. Previously implanted hydrogels were subsequently removed, documenting the reversibility of the procedure while allowing the corneas to return to their preoperative condition. Various alloplastic materials were then reimplanted into the same intrastromal pockets. Medium and high water content lenses produced good results without affecting the recipient cornea, whereas thick or low water content materials extruded or produced severe anterior segment inflammation. The use of medium and high water content, convex-shaped lenticles for the correction of aphakia is possible using current techniques.

Animals↗
PubMed1984

Refractive keratoplasty: myopic keratomileusis in baboons.

We performed 8 myopic keratomileusis procedures in a baboon (Papio cynocephalus) model using the same instruments and techniques which are presently clinically employed. We requested 10 diopters of refractive correction and were able to achieve a mean keratometric correction of 5.5 diopters (range 2.4-8.4) in 6 eyes. Keratometric data in the two remaining eyes was not obtained, because of distortion of corneascope photographs. We did not encounter any technical problems at surgery or during the 2-1/2 to 6 month postoperative period of followup. Morphologic analysis demonstrated subclinical, focal breaks in Bowman's membrane in all specimens and keratocyte repopulation in 7 of 8 eyes. We did find a wide range in the central thickness of the excised corneas which can account for the undercorrections achieved. We consider the baboon model to be excellent for the evaluation of myopic keratomileusis.

Animals↗
PubMed1984

Keratocyte attachment to hydrogel materials.

We have developed an in-vitro model for keratocyte interactions with hydrogel materials. With the aid of inverted phase contrast microscopy and scanning electron microscopy, we observed the growth of baboon stromal keratocytes on the surface of various hydrogel materials. In this study, the Bioflex lens (0.5% hydration) surface was extensively covered with keratocytes, whereas 1% to 25% of the surfaces of Crofilcon A (40% hydration) and Perfilcon A (70% hydration) lenses were covered with keratocytes. The Bufilcon A (55% hydration) lens was free of keratocyte attachment. Keratocytes attached to the surfaces of the lenses produced extracellular collagenous material as evidenced by positive staining with alcian green-metanil yellow. These in-vitro results correlate with our non-human primate studies using Bioflex, Crofilcon A and Bufilcon A lenses as intracorneal implants.

Animals↗
PubMed1984

Morphology of hydrogel implants used for refractive keratoplasty.

The pathology of 14 keratophakia procedures in nine nonhuman primates using various hydrogel lenses as donor lenticles is presented. The lenses were treated as if they were human donor corneas using currently practiced keratophakia procedures. This included microkeratome resection of the recipient cornea, staining of the lenses before cryolathing and, in most instances, lathing according to a modified computer program after which the lenses were inserted into the previously dissected recipient lamellar bed. There was no histologic evidence of an inflammatory reaction to the hydrogels. The major pathologic feature was the presence of activated keratocytes lining the dissected intrastromal pockets.

Animals↗
PubMed1984

Epikeratophakia: clinical evaluation and histopathology of a non-human primate model.

We performed four aphakic and two myopic epikeratophakia procedures in a non-human primate model using two fresh and three prefrozen corneas and one glycerin-preserved cornea. The experiments were terminated 4 to 5 months postoperatively, and the eyes examined with correlative microscopy. The glycerin-preserved cornea sloughed and was not available for analysis. All but one prefrozen specimen demonstrated donor keratocyte repopulation. Active keratocytes were noted lining the optical interface. Focal areas of missing Bowman's layer were present in three recipient corneas. Epithelial interface ingrowth occurred in two specimens. The recipient corneas were otherwise normal.

Animals↗
PubMed1983

Acute morphologic features of radial keratotomy.

We performed eight partially penetrating incisions in 19 eye-bank, 12 nonhuman primate, and 34 canine eyes. Evaluation of the posterior corneal surface by vital staining, correlative microscopy, with corneal incisions set from 80% to 110% of central pachymetric thickness, in three eyes demonstrated damage to the endothelium without anterior chamber perforation. Posterior folds in Descemet's membrane under an incision site was present in all specimens. Potential optical aberrations could be produced about the visual axis depending on the direction of the corneal incisions. Based on this study, the radial keratotomy procedure performed with up to eight deep incisions may produce optic defects. We recommend animal studies to assess the long-term effects of this procedure on the cornea and especially the endothelium.

Adult↗
PubMed1982

Refractive keratoplasty: microkeratome evaluation.

We performed routine microkeratome and freehand lamellar keratectomies in 65 canine eyes and 24 human eye-bank eyes. The microkeratome technique produced more predictable resections compared with the freehand technique and at the same time produced a wound that would allow for better wound coaptation. Neither technique damaged the corneal endothelium. We conclude that one of the reasons for the success of the refractive keratoplasty procedures is the refined microkeratome technique.

Animals↗
PubMedDate not supplied

Hydrogel keratophakia in non-human primates.

We performed sixteen keratophakia procedures in nine non-human primates using various hydrogel lenses (38% to 79% water) as donor corneas (lenticules). The lenses were treated as if they were donor human corneas using currently practiced keratophakia procedures including microkeratome resection of the recipient cornea, staining of the lenses before cryolathing and, in some cases, lathing according to a modified computer program after which the lenses were inserted into a previously dissected recipient lamellar pocket. This technique was able to produce steepening of the cornea up to 44.8 diopters and was well tolerated for over three months. The use of hydrogel lenses could potentially eliminate many of the negative aspects of the use of human donor corneas for the surgical correction of aphakia.

Animals↗