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P J Ousley

Publications and source records attributed to P J Ousley.

10 recordsLinked to original sources
PubMed2001

Endothelial replacement without surface corneal incisions or sutures: topography of the deep lamellar endothelial keratoplasty procedure.

PURPOSE: To evaluate the immediate postoperative corneal topography after the deep lamellar endothelial keratoplasty procedure. METHODS: Eight eye bank eyes underwent deep lamellar endothelial keratoplasty through a 9.0-mm limbal incision replacing the central 7.0 mm of posterior stroma and endothelium through the lamellar pocket wound. Orbscan topography was performed before and after surgery, and simulated keratometry readings and central corneal diopter power were recorded. The change in astigmatism and corneal power from preoperative to postoperative readings was then determined. RESULTS: The net change in corneal astigmatism averaged 0.4+/-0.5 diopters (range, -0.1 to 1.1 diopters). The net change in corneal power averaged -0.2+/-0.4 diopters of flattening (range, -0.9 to +0.2 diopters). Neither the astigmatism nor the corneal power levels after this surgery were significantly different from the preoperative topography (p = 0.22 and 0.27, respectively). CONCLUSIONS: The deep lamellar endothelial keratoplasty procedure, with its absence of corneal surface incisions or sutures, has no significant effect on immediate postoperative corneal topography. The potential advantages of this procedure over penetrating keratoplasty in the treatment of endothelial dysfunction are considerable.

Astigmatism↗
PubMed2001

Deep lamellar endothelial keratoplasty in the first United States patients: early clinical results.

PURPOSE: To report the early clinical results of the first U.S. patients to undergo deep lamellar endothelial keratoplasty (DLEK) surgery for the treatment of endothelial dysfunction. METHODS: Two patients with pseudophakia with Fuchs' endothelial dystrophy, under an Institutional Review Board-approved protocol, underwent replacement of the endothelium through a limbal, scleral pocket incision (DLEK). Their vision, pachymetry, and corneal map topography were measured in the early postoperative period and were compared with preoperative measurements. RESULTS: Both patients had improvement in all parameters within 1 month after surgery, and corneal topography showed no significant change from before the surgery. The first patient's vision at 6 months was 20/40 (+2) with a 0.75-diopter (D) decrease in astigmatism and a normal pachymetry of 573 microm. The second patient's vision at 6 months was 20/40 (-2) with a 0.25-D increase in astigmatism and a pachymetry of 618 microm. Graft endothelial cell counts at 6 months were 1,692 and 2,631 cells/mm2, respectively. CONCLUSION: The DLEK procedure, with its absence of corneal surface incisions and sutures, preserves the preoperative topography and demonstrates good donor endothelial cell count and function early in the postoperative period. If interface clarity can be maintained, the potential advantages over penetrating keratoplasty in the treatment of endothelial dysfunction are considerable.

Aged↗
PubMed1999

Evaluation of prior photorefractive keratectomy in donor tissue.

PURPOSE: To describe a case in which an eye donor had prior bilateral photorefractive keratectomies and to elucidate possible methods of evaluation and screening of donor tissue. METHODS: Case report. A 62-year-old eye donor was reported to have received radial keratotomy before his death. Further investigation by the eye bank showed a history of photorefractive keratectomy (PRK), not radial keratotomy. The corneas were therefore not used for transplantation, and the eyes were evaluated by slit-lamp examination, photography, corneal topography, and histology. RESULTS: Slit-lamp and photographic examination did not indicate the presence of PRK ablations. Corneal topography mapping with the TMS-1 was relatively ambiguous for identifying PRK flattening, while multiple data formatting of the cornea with the Orbscan resulted in the strongest suggestion of prior PRK. Histologic analysis showed central corneal thinning and loss of Bowman's membrane consistent with PRK. CONCLUSIONS: In the absence of a positive donor history for PRK, current methods of screening donor tissue for prior PRK often are insufficient to exclude these corneas from use in transplantation. More refined placido imagery corneal topography or newer technologies such as the Orbscan may allow more sensitive and specific methods of donor tissue screening.

Contraindications↗
PubMed1999

New screening methods for donor eye-bank eyes.

PURPOSE: Current methods of screening donor eyes for corneal transplantation are not always effective in excluding corneas with abnormal topography. We used the Orbscan to determine whether corneal-thickness maps could be used as a technique for donor tissue screening. METHODS: Forty eye-bank eyes were measured with the Orbscan, and a corneal-thickness map was generated. Average central pachymetry measurements from each map were compared with the thinnest midperipheral thickness reading. Two eyes from a donor who had photorefractive keratectomy (PRK) and two eyes from a donor with keratoconus were then compared with the normal donor eye results. RESULTS: The average difference between the thinnest midperipheral pachymetry and the central pachymetry in the control group was 0.040 +/- 0.026 mm. The eyes from the donor with PRK showed larger disparities between the central and midperipheral thicknesses because of the thinned central cornea, with differences of 0.154 mm in the right eye and 0.106 mm in the left eye. The eyes from the donor with keratoconus had midperipheral corneas that were thinner than the center, indicating eccentric, ectatic cones. The differences in thickness between the center and midperiphery in the eyes from the donor with PRK and the donor with keratoconus differed from the control group by >2 SD. CONCLUSIONS: Diseases or surgery that affect the relationship between the central and midperipheral corneal thickness may be screened through Orbscan pachymetry mapping with comparison with a normal range.

Aged↗
PubMed1996

Hydration effects on corneal topography.

OBJECTIVE: To evaluate the effect of corneal thickness changes on the central and paracentral corneal topography in de-epithelialized eye-bank eyes at various stages of hydration. METHODS: Corneal topography of 12 eye-bank eyes was measured with a videokeratoscope at the following four stages of hydration: prethinning (mean pachymetry, 0.88 mm), postthinning (0.55 mm), after 15 minutes of rehydration (0.60 mm), and after 30 minutes of rehydration (0.64 mm). RESULTS: Corneal thickness changes were significant between each stage of hydration (P < .05 by repeated-measures analysis of variance). No net astigmatic shifts were observed between any stage of hydration (P = .45). From prethinning to postthinning, dehydration produced average central corneal steepening of 0.44 diopters (P < .001), and average paracentral steepening of 0.89 D (P < .001). Significant changes in corneal power were not measured during normal rehydration until 30 minutes posthydration, when the central cornea had flattened an average of 0.3 D from normal thickness (postthinning) levels (P < .05). CONCLUSIONS: Substantive thinning of corneal tissue caused statistically significant but clinically minimal ( < 1 D) central and paracentral steepening, but smaller corneal hydration changes that can occur during experimental and surgical procedures had little effect on corneal topography.

Aged↗
PubMed1994

Hydration changes in cadaver eyes prepared for practice and experimental surgery.

OBJECTIVES: To identify reliable and efficient methods of thinning postmortem corneas for surgical experiments and to develop methods of maintaining stable corneal thickness. METHODS: Three methods of corneal thinning were evaluated by group: group A, increased intraocular pressure; group B, exchange of anterior chamber fluid with dextran solution and immersion in dextran solution; and group C, immersion in dextran solution without aqueous replacement. The stability of the thinned central cornea was then evaluated by exposing 30 corneas thinned by methods used in groups B and C to air, Balanced Salt Solution drops (Alcon, Fort Worth, Tex), or dextran solution drops. RESULTS: By 1 hour, the thinning method used in group A resulted in only three of 11 eyes achieving normal central corneal thickness. The method used in group B resulted in normal central thickness in 14 of 14 corneas and in group C, in nine of 15 corneas, at 1 hour. Once thinned by methods used in group B or C, air exposure further thinned the 30 additional corneas by 22% to 26%, Balanced Salt Solution drops thickened the corneas by 16% to 22%, and dextran solution drops stabilized the corneas with only 5% to 13% additional thinning. CONCLUSIONS: Hyperosmolar solutions were more efficient than pressure gradients in thinning the cadaver central cornea. Hydration shifts of the de-epithelialized cornea were dramatic with use of Balanced Salt Solution drops or drying and were minimized with use of hyperosmolar topical solutions.

Aged↗
PubMed1991

Cooling augments alpha 2-adrenoceptor-mediated contractions in rat tail artery.

Experiments were performed to assess the effects of acute moderate cooling on postjunctional alpha 1- and alpha 2-adrenoceptors in isolated rings of tail arteries from male Sprague-Dawley rats. Rings were contracted with norepinephrine (NE; 10(-9) to 10(-4) M) alone or in the presence of prazosin (Pz; 3 x 10(-7) M) or rauwolscine (Rw; 10(-7) M). NE concentration-response curves were inhibited by alpha 1-blockade (Pz) but not significantly affected by alpha 2-blockade (Rw). In all rings, cooling caused an increase in the slope of the dose-response curve and a significant increase in the concentration of agonist required to evoke contractions, as assessed by that concentration of NE required to evoke a contraction equal to 10% of maximal (EC10). Cooling inhibited contractions evoked by the selective alpha 1-adrenergic agonist phenylephrine (PE) as assessed by EC10 but had no significant effect on the weak contractions elicited by the selective alpha 2-adrenergic agonist B-HT 920. Prior elevation of tone with either KCl or prostaglandin F2 alpha enhanced alpha 2-mediated contractions. These contractions were augmented by cooling, whereas those caused by either KCl or prostaglandin F2 alpha alone were not significantly affected. Our results suggest that alpha 2-adrenoceptor-mediated responses in this blood vessel are dependent on the level of preexisting tone and are potentiated by cooling.

Animals↗
PubMed1990

The effects of cooling on human saphenous vein reactivity to adrenergic agonists.

Human saphenous veins were obtained at surgery and assayed immediately (n = 10). The veins were cut into rings, suspended in organ chambers, and connected to force transducers for the recording of isometric tension. One ring served as control whereas others were treated with the alpha 1-adrenoceptor antagonist prazosin (3 X 10(-7) mol/L), or the alpha 2-adrenoceptor antagonist rauwolscine (10(-7) mol/L). In quiescent rings cooling from 37 degrees C to 24 degrees C had no significant effect. Norepinephrine (10(-8)-10(-5) mol/L) caused concentration-dependent contractions with an EC20 (-log concentration of norepinephrine required to induce contractions 20% of maximal) = 6.97 +/- 0.10. The contractions were inhibited by prazosin (EC20 = 5.89 +/- 0.17, p less than 0.001) and rauwolscine (ED20 = 5.78 +/- 0.11, p less than 0.001). In control rings cooling potentiated contractions evoked at concentrations of norepinephrine below 10(-6) mol/L and inhibited those at higher concentrations. In rings treated with alpha-antagonists cooling depressed the maximal contractile responses. Contractions to the alpha 1-agonist, phenylephrine (10(-7)-10(-4) mol/L), were inhibited by cooling, whereas those to the alpha 2-specific agonist B-HT 920 (10(-7)-10(-4) mol/L) showed a pattern similar to that seen with norepinephrine. The data indicate that the human saphenous vein possesses both alpha 1- and alpha 2-adrenoceptors postjunctionally, and that both contribute to contractile responses. Cold augments saphenous vein reactivity to norepinephrine by an apparent increase in the responsiveness of alpha 2-adrenoceptors to agonists. The relationship between temperature and adrenoceptor responsiveness may be of pivotal importance in defining the mechanism of cold-induced vasospasm.

Cold Temperature↗
PubMedDate not supplied

Variability in corneal thickness before, during, and after radial keratotomy.

BACKGROUND: Precision in radial keratotomy requires accurate pachymetry for safety and efficacy. We evaluated the location, timing, and extent of changes in corneal thickness between those determined by preoperative measurement in the clinic and those determined by pre-incision and post-incision measurement in the operating room. METHODS: Sixty eyes of 37 patients had ultrasonic pachymetry measurements of the central and paracentral cornea taken in the clinic 20 minutes before each patient underwent radial keratotomy. The pachymetry was repeated intraoperatively immediately before and, in a subset of 17 eyes, immediately after incisions were made, and the readings were compared. RESULTS: The thinnest of the four paracentral readings measured just prior to placing the radial keratotomy incisions was located temporally in 92% of the eyes and inferiorly in 8%. Corneas progressively thinned from clinic to surgery by an average of 7 +/- 12 microns centrally and 10 +/- 18 microns temporally. Additional thinning of 13 +/- 14 microns centrally and 22 +/- 23 microns temporally occurred during surgery. CONCLUSION: The thinnest paracentral corneal region measured in an eye was not always located in the same quadrant preoperatively and intraoperatively. During the time of incision placement, significant corneal thinning had occurred at each incision site. Individual variations in corneal thickness between that measured preoperatively and that measured during surgery cautions against the use of clinic readings for diamond knife settings during radial keratotomy.

Cornea↗