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Biomedical subjects

H V Gimbel

Publications and source records attributed to H V Gimbel.

At least 19 recordsLinked to original sources
PubMed2001

Diffuse lamellar keratitis: isolation of endotoxin and demonstration of the inflammatory potential in a rabbit laser in situ keratomileusis model.

PURPOSE: To systematically examine sources of endotoxin contamination in eye centers as a potential cause of diffuse lamellar keratitis (DLK) and to demonstrate the inflammatory potential of endotoxin in a rabbit model of laser in situ keratomileusis (LASIK) surgery. SETTING: University of Calgary, Calgary, Alberta, Canada. METHODS: In this prospective study, all water sources that routinely come in contact with LASIK instruments, including sterilizer reservoirs, eyedrops, microkeratome blades, and cleaning solutions, were examined for endotoxins at 5 eye centers. Bacterial cultures were performed on water samples from 5 sterilizer reservoirs. A LASIK flap was created in 8 rabbit eyes using an Automated Corneal Shaper microkeratome (Bausch & Lomb). The flaps were reflected, and a dose of endotoxin at various concentrations was placed on the interface. After 1 minute, the flap was irrigated and repositioned. The rabbit eyes were examined daily with a slitlamp biomicroscope for 3 days for the development of DLK, which was classified on a scale from grade 1 to 4 (mild to severe). The rabbits were killed at the conclusion of the study, and the interfaces were stained to rule out infectious etiologies. RESULTS: Endotoxin was detected in significant concentrations in tap water, filtered and distilled water, instrument washbasins, and sterilizer reservoirs at all 5 centers. The cultures of the water samples taken from the sterilizer reservoirs ranged from no growth to the presence of >100 colony-forming units of Flavobacterium and Pseudomonas aeruginosa. Endotoxins caused DLK-like interface inflammation in all eyes tested. Examination of stained scrapings showed no microorganisms in the interface of the rabbit eyes. CONCLUSION: Endotoxin contamination was detected in water sources that routinely come in contact with LASIK instruments. Endotoxins were capable of inducing interface inflammation in a rabbit model and may therefore be a significant factor in epidemic DLK.

Animals↗
PubMed2001

Accuracy and predictability of intraocular lens power calculation after laser in situ keratomileusis.

PURPOSE: To study the accuracy and predictability of intraocular lens (IOL) power calculation in eyes that had laser in situ keratomileusis (LASIK). SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: Refractive outcomes in 6 cataract surgery and lensectomy eyes after previous LASIK were analyzed retrospectively. Target refractions based on measured and refraction-derived keratometric values were compared with postoperative achieved refractions. Differences between target refractions calculated using 5 IOL formulas and 2 A-constants and achieved refractions were also compared. RESULTS: The refractive error of IOL power calculation in postoperative LASIK eyes was significantly reduced when refraction-derived keratometric values were used for IOL power calculation. Persistent residual hyperopia still occurred in some cases; this was corrected by hyperopic LASIK. Refractive results appeared more accurate and predictable when the Holladay 2 or Binkhorst 2 formula was used for IOL power calculation. CONCLUSION: Hyperopic error after cataract surgery in post-LASIK eyes was significantly reduced by using refraction-derived keratometric values for IOL power calculation. Persistent hyperopic error was corrected by hyperopic LASIK.

Adult↗
PubMed2001

Late traumatic flap dislocation after laser in situ keratomileusis.

Three patients who had laser in situ keratomileusis (LASIK) experienced severe direct corneal trauma 3 to 38 months postoperatively. Flap dislocation resulted in all 3 patients. Presentation following trauma ranged from a few hours to 9 days. All patients were successfully managed by surgical flap repositioning, and all maintained a best corrected visual acuity of 20/20. A literature review of traumatic flap dislocation cases and the most recent methods of diagnosis and management are included.

Adult↗
PubMed2001

Minimizing the risk of recutting with a Hansatome over an existing Automated Corneal Shaper flap for hyperopic laser in situ keratomileusis enhancement.

We report a case series of 4 eyes to discuss the intraoperative complications of recutting a laser in situ keratomileusis (LASIK) flap with a Hansatome microkeratome over an existing 160 microm Automated Corneal Shaper flap for the retreatment of hyperopia. In the eyes that were recut, slivers of stroma were apparent on reflection of the flap; the slivers were located centrally in the 180 microm eye and peripherally in the 160 microm eyes. Recutting a flap for LASIK retreatment runs the risk of visually significant stromal irregularities.

Corneal Stroma↗
PubMed2001

Accuracy of Orbscan pachymetry measurements and DHG ultrasound pachymetry in primary laser in situ keratomileusis and LASIK enhancement procedures.

PURPOSE: To assess the accuracy and variability in pachymetry measurements obtained by Orbscan and by DGH ultrasound in primary laser in situ keratomileusis (LASIK) and LASIK enhancement procedures. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: A retrospective analysis of 906 consecutive primary LASIK and 183 consecutive LASIK enhancement procedures for which preoperative DGH ultrasound and Orbscan pachymetry measurements were obtained. The theoretical residual corneal thickness was compared to measurements by both instruments in 60 eyes that had primary procedures and enhancements. RESULTS: In primary LASIK eyes, the DGH ultrasound measurements were thicker than the Orbscan measurements by a mean of 18.4 microm +/- 17.4 (SD). The DGH ultrasound measurements were thicker than the Orbscan measurements by a mean of 50.1 +/- 40.7 microm in preenhancement pachymetry measurements. The DGH ultrasound measurements were consistent with theoretical residual corneal thickness, 493.0 +/- 42.0 microm versus 487.0 +/- 31.0 microm (P =.65), while Orbscan measurements were statistically less than the theoretical residual corneal thickness, 431.0 +/- 42.0 microm versus 468.0 +/- 39.0 microm (P =.0001). CONCLUSION: DGH ultrasound was a more accurate measurement of corneal pachymetry than Orbscan. The discrepancies between DGH ultrasound and Orbscan pachymetry measurements were more prominent in eyes that had had LASIK.

Cornea↗
PubMed2000

A comparison of the rate of refractive growth in pediatric aphakic and pseudophakic eyes.

OBJECTIVE: To compare the rate of refractive growth in pseudophakic children's eyes to that of aphakic eyes. DESIGN: Multicenter, retrospective observational case series. PARTICIPANTS: 83 patients with pseudophakic eyes (100 eyes) and 74 patients with aphakic eyes (106 eyes), with an age of surgery between 3 months and 10 years and a minimum follow-up time of 3 years or more, depending on the age at surgery. METHODS: A logarithmic model was used to analyze the rate of refractive growth for each eye. MAIN OUTCOME MEASURES: Age at surgery, intraocular lens power, intraocular lens A-constant, initial postoperative refraction, final refraction, and final age. RESULTS: Overall, pseudophakic eyes showed a lesser rate of refractive growth than aphakic eyes (-4.6 diopter vs. -5.7 diopter, P = 0.03). This trend was also present but less significant when the eyes were grouped into those less than 6 months of age at surgery (-3.3 diopter vs. -4.6 diopter, P = 0.09) and older patients (-5.0 diopter vs. -6.1 diopter, P = 0.07). However, the mean quantity of myopic shift was greater in pseudophakic eyes than in aphakic eyes (-5.26 diopter vs. -4.54 diopter), despite shorter follow-up times in the pseudophakic eyes. This is due to the optical effects of a constant intraocular lens power in a growing eye. CONCLUSIONS: Pediatric pseudophakic eyes have a slightly lesser rate of refractive growth than aphakic eyes. The new rate values should be used for predicting future refractions in these eyes.

Aphakia, Postcataract↗
PubMed2000

Accuracy and predictability of intraocular lens power calculation after photorefractive keratectomy.

PURPOSE: To investigate the accuracy and predictability of intraocular lens (IOL) power calculation in postoperative photorefractive keratectomy (PRK) eyes. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: The results in 5 cataract surgery eyes that had had PRK were analyzed retrospectively. Target refractions based on actual and refraction-derived keratometric values were compared with postoperative achieved refractions. The target refractions calculated using 5 IOL formulas and 2 A-constants were also compared with the achieved refractions. RESULTS: In postoperative PRK eyes, the power calculation was more accurate and predictable when the smaller of either the actual or refraction-derived keratometric value was used to calculate the IOL power. The difference between target and achieved refractions appeared smaller when the Binkhorst formula was used. No significant hyperopic shift was observed after cataract surgery. CONCLUSION: The smaller of the actual or the refraction-derived keratometric value is recommended for calculating IOL power in post-PRK eyes.

Adolescent↗
PubMed2000

Postoperative complications in laser in situ keratomileusis.

Laser in situ keratomileusis (LASIK) has become the most common procedure to correct refractive errors in North America. Increasing numbers of patients and surgeons are choosing LASIK in the management of low and moderate myopia, astigmatism, and hyperopia. LASIK presents a unique group of postoperative challenges and complications. It is important to be able to identify these complications in the early and late postoperative periods and to provide effective management. In this article, we review the most commonly encountered early and late postoperative complications after LASIK and the most current methods in prevention and treatment.

Humans↗
PubMed1999

Simultaneous bilateral laser in situ keratomileusis: safety and efficacy.

OBJECTIVE: To compare the safety and efficacy of simultaneous bilateral to sequential bilateral laser in situ keratomileusis (LASIK) surgery for the correction of myopia. DESIGN: Retrospective, nonrandomized, comparative trial. PARTICIPANTS: A total of 2142 consecutive simultaneous and sequential bilateral myopic LASIK surgery eyes operated from March 1996 through June 1998 for the correction of myopia were reviewed. INTERVENTION: Two surgeons (HVG and JAV) performed myopic LASIK using the Nidek EC-5000 excimer laser and either the Chiron Automated Corneal Shaper or the Bausch & Lomb Hansatome microkeratome. MAIN OUTCOME MEASURES: The incidence of intra- or perioperative complications for sequential and simultaneous bilateral LASIK for myopia was recorded. Refractive and visual outcomes at 3 to 6 months postoperative were analyzed. Deviations from targeted spherical equivalent (SE), uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and retreatment rates are reported. RESULTS: Laser in situ keratomileusis was performed on the first eye of 1853 patients scheduled for simultaneous bilateral myopic LASIK. Of these, 28 (1.5%) first eyes had intraoperative or perioperative complications. The second eye surgery was cancelled in 11 cases, and 1842 second eyes completed simultaneous surgery; 13 (0.7%) intraoperative or perioperative complications occurred. Of these 41 complications in simultaneous cases, 1 eye lost 1 line of BCVA at 6 months follow-up. Two hundred eighty-nine patients were scheduled for sequential bilateral myopic LASIK. Five (1.8%) first eyes of the sequential cases had intraoperative complications compared with four (1.4%) sequential second eyes. There was no loss of BCVA in any sequential bilateral case with complications at a minimum at 6 months follow-up. There was no statistically significant difference between intra- and perioperative complication rates comparing simultaneous to sequential bilateral LASIK. Three to 6 months postoperative visual and refractive data were reviewed; except when comparing simultaneous first eye postoperative SE to sequential first eye, there was no statistically significant difference in refractive or visual outcomes, including deviation from targeted SE, UCVA, BCVA, and retreatment rates. CONCLUSION: Simultaneous bilateral LASIK is as safe and effective as sequential surgery. Simultaneous bilateral LASIK may offer several benefits to the patient.

Adult↗
PubMed1999

Comparison of 4 topical anesthetic agents for effect and corneal toxicity in rabbits.

PURPOSE: To compare the onset time, duration of action, corneal toxicity, and corneal epithelial healing time of 4 topical anesthetic agents in rabbits. SETTING: Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada. METHOD: Fifty-six rabbits were treated with 4 topical anesthetics (bupivacaine, lidocaine, procaine, and benzocaine) at different concentrations and different pH of solutions. Corneal sensation, corneal toxicity, and corneal epithelial healing time were measured. RESULTS: The onset time of all 4 anesthetic agents was within 1 minute; however, bupivacaine and lidocaine produced significantly longer action than procaine or benzocaine (P < .05). Buffered bupivacaine and lidocaine had a significantly longer anesthetic effect than that of the nonbuffered solutions (P < .05). No significant effect on corneal epithelial healing time or corneal toxicity was observed. CONCLUSION: Topical bupivacaine and lidocaine had a longer anesthetic effect, particularly in buffered solutions. No significant corneal toxicity was observed.

Anesthetics, Local↗
PubMed1999

Combined cataract surgery, intraocular lens implantation, and viscocanalostomy.

PURPOSE: To describe 2 techniques of combined viscocanalostomy and phacoemulsification and report the results. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: Combined viscocanalostomy, phacoemulsification, and intraocular lens implantation was performed in 83 eyes. A shared scleral incision was made in 46 eyes and a clear corneal incision separate from the viscocanalostomy site, in 37 eyes. A retrospective review of these cases was performed. RESULTS: Intraocular pressure (IOP) was significantly lower in both groups 2 and 8 weeks and 6 months postoperatively. The decline in IOP postoperatively over time was also comparable. There were no cases of hypotony, choroidal detachment, filtrating bleb, or postoperative cystoid macular edema in either group. Complications included IOP spikes in 2 eyes in the shared-incision group at 1 day (to 43 and 30 mm Hg, respectively). In early shared-incision cases, there was 1 obvious Descement's puncture in 1 eye and a torn scleral flap requiring extra suturing in another eye. CONCLUSION: Combined viscocanalostomy, cataract extraction, and IOL implantation was safe and efficacious in lowering IOP whether a shared scleral incision or a separate clear corneal incision was used for phacoemulsification.

Aged↗
PubMed1999

Photorefractive keratectomy in keratoconus suspects.

PURPOSE: To compare the refractive outcome after photorefractive keratectomy (PRK) in keratoconus-suspect patients with that in patients with normal corneal topography. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHOD: In a retrospective study, 3 patients (5 eyes) with unusually shaped corneal topography before surgery were selected as keratoconus suspects. Corneal topography (inferior-superior [I-S] value, central corneal power, and central power difference between both eyes), preoperative and 1 year postoperative refraction, and visual acuity in the keratoconus suspects were compared with those in a control group. RESULTS: The mean preoperative I-S value was 1.79 diopters (D) in the keratoconus-suspect eyes and 0.35 D in the control group eyes (P = .0001). The I-S value of individual corneas in the keratoconus suspects was more than 2 standard deviations above the mean in the control group except in 1 eye in which the steepened area was located in the central cornea. The central power difference between the eyes of this patient was 3.60 D, which was significantly higher than that in the control group. The refractive outcomes in the keratoconus suspects were comparable to those in the control group. CONCLUSION: In this study, the refractive outcomes after PRK in the keratoconus suspects and controls were comparable. However, further investigation with a larger sample and longer follow-up is needed.

Adult↗
PubMed1999

Effect of diclofenac sodium and dexamethasone on cultured human Tenon's capsule fibroblasts.

BACKGROUND AND OBJECTIVE: To investigate the effect of diclofenac sodium and dexamethasone on cultured human Tenon's capsule fibroblasts. MATERIALS AND METHODS: Two experiments were conducted. In the first experiment, fibroblasts were treated with either diclofenac sodium or dexamethasone at different concentrations, and the cell growth was quantified by using Coulter counter and hexosaminidase methods at 1, 3, 5, and 7 days after adding the drugs. In the second experiment, the cells were treated with each drug for 24 hours and then the cultures were switched to a drug-free medium. The cell growth was quantified at day 7 after removing the drugs from the medium. RESULTS: In the first experiment, inhibition of fibroblast growth in a dose-dependent manner was observed from days 1 to 7 in the cultures treated with each drug. The inhibitory was more pronounced in the diclofenac treated cultures. The typical spindle-shaped fibroblasts treated with higher concentrations of the drugs became spherical cells. In the second experiment, inhibition was not observed when the cultures were switched to a drug-free medium. The spherical cells recovered to spindle-shaped cells and proliferated as normal cells. CONCLUSION: Our results have shown that diclofenac sodium and dexamethasone can significantly inhibit human Tenon's capsule fibroblast growth in a cell culture model. The inhibitory effect was not observed when the cultures were switched after 24 hours to a drug-free culture medium.

Anti-Inflammatory Agents, Non-Steroidal↗