Biomedical subjects
John F Salmon
Publications and source records attributed to John F Salmon.
Videoendoscope-guided fluorescein-assisted vitrectomy for phakic malignant glaucoma.
Malignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery in eyes with primary angle closure. Pars plana vitrectomy is reserved for the treatment of malignant glaucoma when medical and laser treatment fail. The primary aim of surgery is the removal of the anterior vitreous to reduce resistance to aqueous flow into the anterior chamber. In phakic eyes, conventional pars plana vitrectomy without lens extraction is frequently unsuccessful because of difficulty visualizing the normally transparent anterior vitreous, combined with the technical challenge of removing the anterior vitreous without damaging the crystalline lens. We describe a technique of intraocular, videoendoscope-guided, fluorescein-assisted pars plana vitrectomy that enables direct visualization and thorough removal of the anterior vitreous without the need for lens extraction in prepresbyopic patients without cataract.
Bleb-associated endophthalmitis.
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Chronic angle-closure glaucoma.
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Factors associated with success in first-time trabeculectomy for patients at low risk of failure with chronic open-angle glaucoma.
PURPOSE: To examine the relationships between study factors and trabeculectomy outcome in a representative sample of United Kingdom ophthalmology surgeons and patients. DESIGN: Cross-sectional observational study by questionnaire. PARTICIPANTS: All ophthalmic surgeons performing trabeculectomy in the National Health Service were invited to select their 4 most recent consecutive trabeculectomy cases satisfying study eligibility criteria before June 1996. Three hundred eighty-two surgeons supplied baseline data for 1450 patients and 1-year follow-up data for 1240 (85.3%) patients. All patients had undergone first-time trabeculectomy for chronic open-angle glaucoma. METHODS: Data were collected by self-administered questionnaires at baseline and 6 and 12 months postoperatively. Univariate analysis of the relationships between study factors and success was performed by chi-square test (categorical variables) and Student's t or Mann-Whitney U tests (continuous variables). Multiple logistic regression modeling of explanatory variables significant at a P value of </=0.1 was then performed. MAIN OUTCOME MEASURE: Trabeculectomy success, defined as a final intraocular pressure (IOP) less than two thirds of the preoperative IOP, excluding patients on antiglaucoma medications. RESULTS: After multiple logistic regression modeling, diabetes (odds ratio [OR] = 0.485, 95% confidence interval [CI] = 0.271-0.868, P = 0.015), superior rectus traction suture (OR = 0.580, 95% CI = 0.348-0.959, P = 0.034), subconjunctival anesthetic (OR = 0.172, 95% CI = 0.065-0.459, P<0.0001), and nonspecialist surgeons (OR = 0.539, 95% CI = 0.335-0.865, P = 0.010) remained significantly associated with poorer outcome. CONCLUSIONS: In this nationally representative sample of glaucoma patients undergoing first-time trabeculectomy, we have identified important associations between diabetes, superior rectus traction suture, subconjunctival anesthetic, nonspecialist surgeons, and diminished trabeculectomy success. These associations merit further examination.
Long-term effect of cataract surgery on intraocular pressure after trabeculectomy: extracapsular extraction versus phacoemulsification.
PURPOSE: To compare the effect of phacoemulsification with intraocular lens (IOL) implantation on long-term intraocular pressure (IOP) control in glaucoma patients who had previous trabeculectomy with the effect on IOP control in similar patients after extracapsular cataract extraction (ECCE) with IOL implantation. SETTING: Oxford Eye Hospital, Oxford, England. METHODS: Twenty-eight consecutive patients who had phacoemulsification with IOL implantation (phaco group) at least 3 months after trabeculectomy were identified from hospital records, and 28 patients who had ECCE with IOL implantation (ECCE group) were matched retrospectively to the phaco group with respect to age, sex, diagnosis, and IOP. In both groups, the IOP before cataract extraction was compared with the IOP at intervals up to 2 years after cataract extraction. A Kaplan-Meier survival analysis was performed. RESULTS: The mean IOP in the phaco group did not differ significantly from the mean IOP before cataract extraction at any interval. Twelve months after cataract extraction, the mean IOP in the ECCE group was significantly higher than preoperatively (P =.01); however, the mean IOP did not differ between groups over time (P =.704). There was significantly better long-term IOP control in the phaco group as determined by Kaplan-Meier survival analysis and the log-rank test (P =.038). CONCLUSION: After trabeculectomy, phacoemulsification provided better long-term IOP control than ECCE; however, the mean IOP was not significantly lower.
Clinical evaluation of the dynamic observing tonometer.
PURPOSE: The Dynamic Observing Tonometer (SmartLens, Ophthalmic Development Company AG, Zürich, Switzerland) is a diagnostic contact lens that allows continuous measurement of intraocular pressure, in addition to providing the investigator with a view of the posterior pole and anterior chamber angle. The purpose of this study was to determine the accuracy of this tonometer and the repeatability of the intraocular pressure measurements. PATIENTS AND METHODS: The intraocular pressure was measured by Goldmann applanation tonometry in one randomly chosen eye of 40 subjects (median age 66 years, range 21-77 years). The intraocular pressure, pulse amplitude and 10-second continuous tonometric recordings were then taken using the Dynamic Observing Tonometer and a pneumatonometer. Accuracy was determined by calculating the mean bias and 95% limits of agreement of measurements made with the Dynamic Observing Tonometer against measurements made with the Goldmann and pneumatonometer. Repeatability was evaluated by calculating the differences between pairs of repeated measurements against the mean value and by calculating reliability coefficients. RESULTS: Intraocular pressure measurements made with the Dynamic Observing Tonometer had a mean bias of +2.1 mm Hg (95% limits of agreement: -4.0 to +8.2 mm Hg) compared with Goldmann tonometry. There was a reasonable correlation between Goldmann and Dynamic Observing Tonometer intraocular pressure readings (r = 0.78, P < 0.01). In measuring pulse amplitude, the Dynamic Observing Tonometer was found to have a mean bias of +0.4 mm Hg (95% limits of agreement: -1.6 to +2.3 mm Hg) compared with the pneumatonometer (r = 0.78, P < 0.01). In assessing the repeatability of intraocular pressure measurements, the first Dynamic Observing Tonometer reading was on average 0.4 mm Hg higher than the second (95% limits of agreement: -3.8 to +4.6 mm Hg) with a coefficient of reliability of 0.91. For pulse amplitude readings, the first reading was on average 0.1 mm Hg lower than the second (95% limits of agreement: -1.4 to +1.2 mm Hg) with a coefficient of reliability of 0.90. CONCLUSION: Intraocular pressure measurements taken with the Dynamic Observing Tonometer had a small positive bias compared with Goldmann tonometry. The pulse amplitude values correlated well with those obtained with a pneumatonometer and the repeatability of intraocular pressure measurements was similar to that found in other commercially available tonometers.
Phacoemulsification with intraocular lens implantation after trabeculectomy.
PURPOSE: To determine the effect of phacoemulsification with intraocular lens (IOL) implantation, using a superior clear-corneal incision, on the long-term intraocular pressure (IOP) control in patients who have undergone previous trabeculectomy. METHODS: Twenty-eight consecutive patients who underwent phacoemulsification with IOL implantation (phaco group) at least 3 months after trabeculectomy were identified and matched to 28 patients who underwent trabeculectomy only (trabeculectomy-only group) with respect to age, gender, IOP, and duration of follow-up. The mean IOP was compared 1 and 2 years after phacoemulsification, and the surgical success rate in each group was determined by Kaplan-Meier survival analysis. RESULTS: The mean IOP 1 year after cataract surgery was significantly higher ( = 0.025) in the phaco group (15.6 +/- 3.5 mm Hg) than in the trabeculectomy-only group (13.4 +/- 2.5 mm Hg), but at 2 years the difference was not statistically significant (15.3 +/- 3.1 mm Hg in the phaco group compared with 14.3 +/- 3.2 mm Hg in the trabeculectomy-only group; = 0.35). Two years after surgery, 5 of 28 patients in the phaco group and 1 of 28 patients in the trabeculectomy-only group had commenced or were using additional topical medication ( = 0.089). If the introduction of glaucoma medication was considered a "failure," then the IOP control was significantly better in the trabeculectomy-only group using two different criteria for surgical failure. CONCLUSION: Although phacoemulsification and IOL implantation through a superior clear-corneal incision have little effect on mean IOP in a group of patients who have undergone previous trabeculectomy, this procedure may jeopardize the long-term IOP control in individual patients.