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George O Waring

Publications and source records attributed to George O Waring.

15 recordsLinked to original sources
PubMed2005

Histologic, ultrastructural, and immunofluorescent evaluation of human laser-assisted in situ keratomileusis corneal wounds.

OBJECTIVE: To evaluate human corneas after laser-assisted in situ keratomileusis at different postoperative intervals. METHODS: Thirty-eight postmortem corneas from 20 patients with postoperative intervals from 2 months to 6.5 years after laser-assisted in situ keratomileusis surgery were collected from eye banks. The corneas were trisected and processed for conventional histologic analysis, transmission electron microscopy, and immunofluorescence. RESULTS: Light microscopy and transmission electron microscopy showed focal undulations in Bowman layer, focal epithelial hypertrophic modifications, and a variably thick (range, 0.4-16.4-mum) lamellar stromal interface scar in all specimens. The flap wound margin, which was adjacent to the epithelium, healed by producing an approximately 8-mum-thick hypercellular fibrotic stromal scar, whereas the central and paracentral wound regions healed differently because a thinner (approximately 5-mum) hypocellular primitive stromal scar was present in all the corneas examined. Immunofluorescence identified increased type 3 collagen and myofibroblasts in the hypercellular fibrotic scar regions and decreased or absent levels of all corneal stromal components other than type 1 collagen in the hypocellular primitive scar regions. CONCLUSIONS: After laser-assisted in situ keratomileusis surgery, the keratocyte-mediated production of a variably thick lamellar corneal stromal scar occurs, resulting in 2 regional types of scarring. The hypercellular fibrotic scar at the wound margin is usually visible clinically and functions to hold the flap in place, while the more central hypocellular primitive scar is not visible clinically and allows easy lifting of the flap postoperatively.

Actins↗
PubMed2005

Ex vivo confocal microscopy of human LASIK corneas with histologic and ultrastructural correlation.

OBJECTIVE: To perform confocal microscopy on postmortem human LASIK corneas and correlate these findings to histologic and ultrastructure evaluations. DESIGN: Prospective, consecutive, observational case series. PARTICIPANTS: Ninety postmortem LASIK corneas (47 patients) were evaluated for histopathology, of which 22 consecutive corneas (12 patients) were also evaluated by confocal microscopy. Six normal corneas (3 patients) served as controls. METHODS: This observational case series involving 22 corneas from 12 patients with postoperative intervals from 1 month to 6.5 years after LASIK surgery were collected. The corneas were mounted in an artificial anterior chamber and perfused with balanced salt solution before confocal microscopy was performed on the center of the cornea. The corneas were then bisected and processed for light and transmission electron microscopy. RESULTS: Confocal microscopy, along with histologic and ultrastructural correlations, demonstrated that the most prevalent alterations in the centers of LASIK corneas were a slightly thickened epithelium caused by focal basal epithelial cell hypertrophic modifications, random undulations in Bowman's layer over the flap surface, and a variably thick hypocellular primitive stromal interface scar. By using confocal microscopy, the interface wound was easily identified in 100% of the cases because numerous brightly reflective interface particles were always present in the hypocellular primitive stromal scar. These particles were found primarily to consist of organic cellular constituents, some of which were transient in nature. CONCLUSION: After LASIK, active stromal wound healing in the central cornea results in the production of a hypocellular primitive stromal scar, whereas secondary tissue adjustments seem to cause the Bowman's layer undulations and the subsequent epithelial cell modifications. Most of the interface particles revealed by confocal microscopy in the region of the stromal scar are organic in nature and presumably innocuous to the cornea.

Adult↗
PubMed2003

Evaluation of hematoxylin and eosin and special stains for the detection of acanthamoeba keratitis in penetrating keratoplasties.

PURPOSE: To compare the efficacy of a battery of routine and special histologic stains for the detection of acanthamoeba keratitis. DESIGN: Observational study. METHODS: Nine patients with culture-proven infectious keratitis whose clinical differential diagnosis included acanthamoeba and who had undergone penetrating keratoplasty were identified. Three cases each of culture-proven acanthamoeba, fungal, and herpes simplex keratitis were reviewed. Serial sections of the keratoplasty specimens were stained with hematoxylin and eosin, periodic acid-Schiff (PAS), Gomori methanamine silver (GMS), giemsa, Gram, calcofluor white, and acridine orange. Sections were reviewed in a random order and a masked fashion and classified as positive or negative for acanthamoeba, fungus, or herpes. RESULTS: The correct diagnosis was made by examination of the hematoxylin and eosin stained slides in all cases. Correct diagnoses in decreasing order of frequency were made for slides stained with PAS, GMS, acridine orange, calcofluor white, giemsa, and Gram. There were false-positive diagnoses made only with calcofluor white and acridine orange stained slides because of staining of extracellular debris and other material. CONCLUSIONS: When sections are examined by an experienced observer, hematoxylin and eosin is useful compared with calcofluor white, acridine orange, GMS, PAS, giemsa, and Gram stains for the detection of acanthamoeba keratitis.

Acanthamoeba Keratitis↗
PubMed2002

Intraocular lens power calculations after laser in situ keratomileusis.

PURPOSE: To compare the accuracy of several techniques for calculating intraocular lens (IOL) power after laser in situ keratomileusis (LASIK). METHODS: Retrospective review of 10 eyes from nine patients undergoing phacoemulsification after LASIK. Corneal power (K) was measured by manual keratometry (MK), refractive history (RH), contact lens overrefraction (CTL), videokeratography (VK), and an average of the refractive history and contact lens methods (AVG 2). Results were compared with the back-calculated K value generated by the Holladay IOL Consultant program. Age-matched patients undergoing phacoemulsification without previous refractive surgery served as controls. RESULTS: Mean spherical equivalent postoperative refraction was +0.21 diopter (D) (SD, 1.54; range, -2.25 to +2.25 D) for patients undergoing cataract extraction after LASIK versus -0.56 D (SD, 0.66; range, -2.375 to +0.5 D; p= 0.16) for controls. Thirty percent of cases versus 90% of controls were within 1 D ( p= 0.002) of emmetropia. Forty percent of cases versus no controls were more than 1 D hyperopic ( p= 0.08). The mean differences for each method compared with the back-calculated K values were MK, +0.82 D; VK, +1.24 D; RH, -0.76 D; CTL, +0.91 D; AVG 2, +0.08 D. The mean absolute deviations from the back-calculated K values were MK, 1.91 D; VK, 2.01 D; RH, 1.68 D; CTL, 1.62 D; AVG 2, 1.42 D. CONCLUSION: Significant refractive errors occurred with each of the methods investigated for determining IOL power after LASIK. RH, CL, or AVG 2 provided the most accurate results.

Adult↗
PubMedDate not supplied

Repositioning the laser in situ keratomileusis flap at the slit lamp.

PURPOSE: To describe the indications and technique for repositioning the laser in situ keratomileusis (LASIK) flap at the slit lamp. METHODS: We present a description of patients with striae or slippage of the flap who had repositioning of the flap at the slit lamp. RESULTS: Indications for repositioning at the slit lamp are mostly flap striae. However, it can also be done for a displaced flap and small amounts of debridement. This procedure is not recommended for taking cultures, irrigation of diffuse lamellar keratitis, suturing the flap, or epithelial ingrowth. Repositioning the flap is done by finding the edge of the flap with the cannula, lifting the flap, sweeping the cannula to release the entire wound, and infusing balanced salt solution under the entire flap. We did not encounter infection or recurrent epithelial erosion in these patients. CONCLUSIONS: Repositioning the LASIK flap at the slit lamp was effective and safe in the treatment of striae or flap slippage. It saved time, money, and, anxiety for the patient.

Adult↗
PubMedDate not supplied

Cohesive tensile strength of human LASIK wounds with histologic, ultrastructural, and clinical correlations.

PURPOSE: To measure the cohesive tensile strength of human LASIK corneal wounds. METHODS: Twenty-five human eye bank corneas from 13 donors that had LASIK were cut into 4-mm corneoscleral strips and dissected to expose the interface wound. Using a motorized pulling device, the force required to separate the wound was recorded. Intact and separated specimens were processed for light and electron microscopy. Five normal human eye bank corneas from 5 donors served as controls. A retrospective clinical study was done on 144 eyes that had LASIK flap-lift retreatments, providing clinical correlation. RESULTS: The mean tensile strength of the central and paracentral LASIK wounds showed minimal change in strength over time after surgery, averaging 2.4% (0.72 +/- 0.33 g/mm) of controls (30.06 +/- 2.93 g/mm). In contrast, the mean peak tensile strength of the flap wound margin gradually increased over time after surgery, reaching maximum values by 3.5 years when the average was 28.1% (8.46 +/- 4.56 g/mm) of controls. Histologic and ultrastructural correlative studies found that the plane of separation always occurred in the lamellar wound, which consisted of a hypocellular primitive stromal scar centrally and paracentrally and a hypercellular fibrotic stromal scar at the flap wound margin. The pathologic correlations demonstrated that the strongest wound margin scars had no epithelial cell ingrowth-the strongest typically being wider or more peripherally located. In contrast, the weakest wound margin scars had epithelial cell ingrowth. The clinical series demonstrated the ability to lift LASIK flaps without complications during retreatments up to 8.4 years after initial surgery, correlating well with the laboratory results. CONCLUSIONS: The human comeal stroma typically heals after LASIK in a limited and incomplete fashion; this results in a weak, central and paracentral hypocellular primitive stromal scar that averages 2.4% as strong as normal comeal stroma. Conversely, the LASIK flap wound margin heals by producing a 10-fold stronger, peripheral hypercellular fibrotic stromal scar that averages 28.1% as strong as normal comeal stromal, but displays marked variability.

Adult↗