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Biomedical subjects

T A Cox

Publications and source records attributed to T A Cox.

At least 19 recordsLinked to original sources
PubMed1999

The Ahmed valve in refractory pediatric glaucoma.

PURPOSE: To evaluate the efficacy of the Ahmed Glaucoma Valve implant in pediatric patients with refractory glaucoma. METHODS: A retrospective chart review was conducted of 27 eyes from 23 consecutive pediatric patients (younger than 18 years) with refractory glaucoma treated with Ahmed Glaucoma Valve implant placement. The main outcome measure was time after surgery without failure. Success was defined as an intraocular pressure of 21 mm Hg or less without visually devastating complications or additional glaucoma surgery (exclusive of tube revision). Previous cycloablation, which was present in a subset of eyes, was examined as a possible influence on postoperative intraocular pressure control, glaucoma medication dependence, and surgical success. RESULTS: The median patient age was 4.8 years (range, 0.3 to 16.8 years), with a follow-up of 3 to 31 months (mean, 12.6 +/- 8.2 months). Intraocular pressure was reduced from a preoperative mean of 32.8 +/- 7.5 mm Hg to 16.7 +/- 5.4 mm Hg at 18 months postoperatively, with an overall success rate of 85.2% at last follow-up. Cumulative probabilities of success by Kaplan-Meier analysis were 90.6% at 12 months and 58.3% at 24 months. Compared with those that did not undergo previous cycloablation, eyes that had undergone previous cycloablation had a lower mean postoperative intraocular pressure at 3- and 6-month follow-up (P < .001 and P = .057, respectively) and required fewer glaucoma medications at postoperative examination time points up to 18 months (P < or = .01 at each time point). Fifteen eyes (56%) required glaucoma medications after surgery. The most common complication was corneal-tube contact, which occurred in five eyes (18.5%). One eye with a wound leak required anterior chamber reformation. Retinal detachment occurred in one aphakic eye 2 years postoperatively, resulting in loss of vision. One eye with neovascular glaucoma required enucleation after an enlarging (presumably preexisting) medulloepithelioma was discovered. CONCLUSIONS: Ahmed Glaucoma Valve implantation is a useful therapy for the treatment of refractory pediatric glaucoma, and it may be safely used in a subgroup of eyes with uncontrolled intraocular pressure despite previous cycloablation procedures.

Adolescent↗
PubMed1999

The importance of fluorescein angiography in planning laser treatment of diabetic macular edema.

OBJECTIVE: To test the hypothesis that pretreatment fluorescein angiography (FA) is not necessary for effective laser treatment of patients with clinically significant diabetic macular edema (CSME). DESIGN: Prospective, randomized, controlled treatment simulation. PARTICIPANTS: Six fellowship trained retina specialists. INTERVENTION: The authors compared the ability of four retina specialists (observers) to plan laser treatment with and without the use of FA. One hundred consecutive cases of CSME were selected, each case consisting of a stereo pair of color photographs and a corresponding fluorescein angiogram. These cases were first read by two retina specialists who reached consensus on a treatment plan for each case (standard map). Each of the 4 observers reviewed 50 of these cases on 2 occasions and plotted 2 sets of treatment maps, 1 set created with and 1 without the aid of FA. Each observer's 100 treatment maps were graded for accuracy by comparing them to the corresponding standard maps. The role of FA in improving the accuracy of treatment maps was evaluated using logistic regression analysis to control for different observers, different cases, and different posterior pole characteristics. MAIN OUTCOME MEASURES: Accuracy was defined as the proportion of standard treatment correctly treated by the observer. RESULTS: For the observers as a group, the use of FA improved treatment planning accuracy from 49% to 54.5% (P = 0.02); however, there was significant interobserver variation in performance (P < 0.001). Treatment planning accuracy without and with FA was as follows: observer 1, 40.8% and 40.2%; observer 2, 49.8% and 72%; observer 3, 56.1% and 59.5%; and observer 4, 49.2% and 46.4%. CONCLUSION: The use of FA improves the accuracy of treatment planning for CSME. The authors' study supports the use of FA in laser treatment of patients with CSME.

Diabetic Retinopathy↗
PubMed1999

Mitomycin C-augumented trabeculectomy with postoperative wound modulation in pediatric glaucoma.

PURPOSE: The purpose of this study was to evaluate mitomycin C-augmented trabeculectomy combined with postoperative subconjunctival 5-fluorouracil and laser suture lysis in the treatment of refractory pediatric glaucoma. METHODS: Twenty-one consecutive cases (17 patients) with refractory pediatric glaucoma treated with mitomycin C trabeculectomy (0.4 mg/mL for 3 to 5 minutes) and postoperative 5-fluorouracil, laser suture lysis, or both were retrospectively reviewed. Success was defined as intraocular pressure between 4 and 16 mm Hg without further glaucoma surgery or devastating complication. RESULTS: The median age of the study population was 2.6 years (range, 0.05 to 16 years). The overall success rate was 52.4%, with a median follow-up of 23 months for successful cases. Success rates for patients older than 1 year of age versus those younger than 1 year of age at surgery were 73% and 30%, respectively. Success rates for phakic versus aphakic eyes were 64% and 29%, respectively. Age and lens status, taken together, were significant predictors of outcome (P = .013). Reasons for failure in this study were uncontrolled intraocular pressure (8 cases), persistent wound leak (1 case), and endophthalmitis (1 case); the latter 2 cases required bleb excision. Other complications encountered included chorioretinal detachment, shallow anterior chamber, 5-fluorouracil toxicity, and cataract formation. No irreversible visual deficits could be attributed to the trabeculectomy procedure or subsequent complications in any of these cases. CONCLUSIONS: Mitomycin C-augmented trabeculectomy combined with postoperative suture lysis and 5-fluorouracil is a viable option for older phakic children with refractory glaucoma. This procedure has a lower success rate in infants and in aphakic eyes. Both early and late postoperative complications are common, and diligent lifelong long-term follow-up is needed to detect bleb leaks and infection. The addition of postoperative suture lysis and 5-fluorouracil to mitomycin C-augmented trabeculectomy did not provide any convincing improvement in the success of this procedure in pediatric patients with refractory glaucoma and may have increased the complication rate.

Adolescent↗
PubMed1999

Acquired convergence-evoked pendular nystagmus in multiple sclerosis.

Nystagmus seen only with convergence is unusual. We describe four cases of acquired convergence-evoked pendular nystagmus in patients with multiple sclerosis. The nystagmus was horizontal and asymmetric in all patients. Eye movement recordings in one subject showed a conjugate rather than a convergent-divergent relationship of the phase of movement between the two eyes. All patients had evidence of optic neuropathy and cerebellar dysfunction. Occlusion of either eye during fixation of near targets led to divergent drift of the covered eye and a decrease in nystagmus. Intravenous scopolamine reduced nystagmus in one patient. Base-in prisms alleviated symptoms of oscillopsia at near and improving reading visual acuity. Convergence-evoked pendular nystagmus may be more common than currently appreciated, particularly among patients with multiple sclerosis.

Adult↗
PubMed1998

A clinical comparison of transscleral cyclophotocoagulation with neodymium: YAG and semiconductor diode lasers.

PURPOSE: To compare the efficacy of transscleral cyclophotocoagulation using a neodymium: YAG (Nd:YAG) or semiconductor diode laser in controlling intraocular pressure in patients with refractory glaucoma. METHODS: In a prospective study, 95 eyes of 91 patients with refractory glaucoma randomly received Nd:YAG or diode cyclophotocoagulation. Patients were followed for a mean of 10.4 months (10.42 +/- 3.16, mean +/- SD). We compared available data preoperatively and at 1 week, 1 month, 6 months, and 12 months postoperatively. Data analyzed were corrected visual acuity, intraocular pressure, and the type of glaucoma. RESULTS: There was a statistically significant decrease in intraocular pressure after both Nd:YAG and diode cyclophotocoagulation at each time period. However, there were no significant differences in postoperative intraocular pressure or visual acuity change between Nd:YAG and diode procedures. CONCLUSIONS: Compared with the Nd:YAG laser for transscleral cyclophotocoagulation, the diode laser has technological advantages including portability, durability, and smaller size, while providing equivalent postoperative intraocular pressure and visual acuity change.

Adult↗
PubMed1998

A comparison of the Marcus Gunn and alternating light tests for afferent pupillary defects.

OBJECTIVE: The authors compared two methods, the Marcus Gunn test and the alternating light test, for detecting a relative afferent pupillary defect. DESIGN: A randomized, prospective clinical trial. PARTICIPANTS: Fourteen patients with unilateral optic neuropathy. INTERVENTION: The Marcus Gunn and alternating light tests were performed on each patient. MAIN OUTCOME MEASURES: The results of the Marcus Gunn and altemating light tests for detecting a relative afferent pupillary defect on the affected side. RESULTS: The Marcus Gunn test was able to identify the affected eye in only 8 of 14 patients, whereas the alternating light test correctly identified the affected eye in 13 of 14 patients. Results of the Marcus Gunn test were indeterminate in 4 of 14 patients and were incorrect in 2 of 14 patients. Results of the alternating light test were indeterminate in one patient and never incorrectly identified the affected eye. CONCLUSION: The alternating light test is superior to the Marcus Gunn test for detecting relative afferent pupillary defects.

Diagnostic Techniques, Ophthalmological↗
PubMed1998

Decrease in intraocular pressure after orbital decompression for thyroid orbitopathy.

BACKGROUND: The effect of thyroid orbitopathy on intraocular pressure (IOP) remains controversial. We carried out a study to determine the effect of orbital decompression surgery on the IOP in patients with advanced thyroid orbitopathy. METHODS: The records of 12 consecutive patients (22 eyes) who underwent decompression surgery for severe thyroid orbitopathy between 1985 and 1996 were reviewed. All patients were maintained on essentially the same medications before and after surgery. The IOP readings, obtained by means of applanation tonometry in primary gaze, from the pre- and postoperative visits were recorded, and the net change was calculated. RESULTS: The mean preoperative and postoperative IOP values were 19.8 mm Hg and 16.8 mm Hg respectively, a significant difference (p = 0.008). Seven of eight eyes with an IOP of 21 mm Hg or greater preoperatively had a postoperative IOP less than 21 mm Hg; these eyes showed a mean decrease in IOP of 5.6 mm Hg. The degree of preoperative IOP elevation was found to be a strong predictor of the amount of IOP lowering after surgery (p = 0.014). INTERPRETATION: Our results support the concept that orbital congestion associated with thyroid orbitopathy produces an increase in IOP by elevation of episcleral venous pressure (EVP) and that orbital decompression may reduce the IOP by decreasing EVP. Decompression surgery may obviate the need for more aggressive management of glaucoma in patients with severe thyroid orbitopathy.

Adult↗
PubMed1997

Argon vs diode laser trabeculoplasty.

PURPOSE: To compare the efficacy of diode laser and argon laser trabeculoplasty in a randomized prospective study of 11 paired fellow eyes. METHODS: Fellow eyes of 11 patients, having had no prior laser trabeculoplasty and requiring laser trabeculoplasty to lower intraocular pressure, were randomly assigned prospectively to diode laser trabeculoplasty in one eye and argon laser trabeculoplasty in the other eye. RESULTS: In the diode laser group, the average baseline intraocular pressure was 21.6 +/- 2.0 mm Hg before trabeculoplasty and 19.6 +/- 2.1 mm Hg (or a 7.7% +/- 11.5% mean pressure reduction) at 1 month, 19.3 +/- 2.6 mm Hg (or a 6.9% +/- 13.5% mean reduction) at 2 months, and 19.0 +/- 3.3 mm Hg (or a 2.4% +/- 16.9% mean reduction) at 3 months postoperatively. In the argon laser group, the average intraocular pressure was 24.4 +/- 3.5 mm Hg before treatment and 17.6 +/- 1.7 mm Hg (or a 24.7% +/- 11.4% mean pressure reduction) at 1 month, 16.8 +/- 2.5 mm Hg (or a 26.7% +/- 15.3% mean reduction) at 2 months, and 15.5 +/- 1.2 mm Hg (or a 30.0% +/- 16.5% mean reduction) at 3 months after laser trabeculoplasty. The difference between argon and diode laser intraocular pressure reduction was statistically significant at 1 month (P < .01), 2 months (P < .01), and 3 months (P < .05) after treatment. CONCLUSION: Argon laser trabeculoplasty appears to be more effective than diode laser therapy in lowering intraocular pressure during the first 3 months after treatment.

Aged↗
PubMed1997

Uveitis in the southeastern United States.

PURPOSE: Previous epidemiologic studies of uveitis have focused on predominantly Caucasian populations, and none have been based in the Southeast. We analyzed the epidemiology of uveitis among a referral population with a high percentage of African Americans in the United States. METHODS: We evaluated demographic data from 385 consecutive patients referred to the Duke Uveitis Clinic. RESULTS: Of the 385 patients, 120 (31%) were African American and 258 (67%) Caucasian; 237 (62%) were female and 148 (38%) male. The most common diagnoses among the 385 patients were idiopathic panuveitis (64 patients [17%]), idiopathic anterior uveitis (47 patients [12%]), pars planitis (46 patients [12%]), sarcoidosis (44 patients [11%]), and toxoplasmosis (39 patients [10%]). These diagnoses were also the most common among the 120 African American patients: 33 patients (28%) had idiopathic panuveitis, 30 (25%) had sarcoidosis, 10 (8%) had idiopathic anterior uveitis, 8 (7%) had toxoplasmosis, and 6 (5%) had pars planitis. Among the 258 Caucasian patients, the most common diagnoses were pars planitis (39 patients [15%]), idiopathic anterior uveitis (37 patients [14%]), toxoplasmosis (30 patients [12%]), idiopathic panuveitis (28 patients [11%]), and multifocal choroiditis and panuveitis (MCP) (17 patients [7%]). Categorizing diagnoses of all 385 patients by anatomic location, panuveitis was most frequent (148 patients [38%]), followed by anterior uveitis (97 patients [25%]), posterior uveitis (93 patients [24%]), and intermediate uveitis (47 patients [12%]). CONCLUSIONS: The higher frequency of sarcoidosis and idiopathic panuveitis than previously reported is related to our larger African American population base. The racial composition of the Southeast does not, however, account for differences such as our higher percentage of MCP; it is possible that other genetic or environmental factors play a role in this region.

Adolescent↗
PubMed1996

Condensation on polymethylmethacrylate, acrylic polymer, and silicone intraocular lenses after fluid-air exchange in rabbits.

PURPOSE: Condensation occurs rapidly on silicone intraocular lenses (IOLs) after vitrectomy and fluid-air exchange in the presence of a posterior capsulotomy, severely limiting the retinal view. Foldable IOLs made of an acrylic polymer are now available. The authors compare the condensation and subsequent retinal view degradation after vitrectomy and fluid-air exchange in rabbit eyes implanted with polymethylmethacrylate (PMMA), soft acrylic polymer (ACRYSOF), and silicone IOLs. METHODS: Thirty rabbits underwent bilateral lens removal. Twenty PMMA, 20 acrylic polymer, and 20 silicone IOLs were implanted into the capsular bag. After three-port vitrectomy, eyes were randomly assigned to undergo a posterior capsulotomy or to an intact posterior capsule. Fluid-air exchange was performed, and the amount of condensation on the IOL surface and resultant retinal view was graded. Surgical maneuvers then were performed to decrease the condensation. These maneuvers included wiping the IOL surface with a soft-tipped cannula and coating it with viscoelastic. RESULTS: No condensation occurred on IOLs in eyes with an intact posterior capsule. Significantly more condensation occurred on IOLs in eyes with a capsulotomy, regardless of IOL type (P < 0.014). Wiping the condensation resulted in significantly less condensation and improved retinal view on the PMMA and acrylic IOLs when compared with the silicone IOLs (P < 0.024). Condensation was eliminated on all three IOL types after viscoelastic was applied. However, increased distortion of the retinal view was induced by the viscoelastic on the silicone IOL as compared with the other IOLs. CONCLUSIONS: Condensation and subsequent retinal image degradation occurs uniformly after vitrectomy, posterior capsulotomy, and fluid-air exchange in eyes with PMMA, acrylic, and silicone IOLs. Because the condensation can be eliminated most easily on acrylic IOLs compared with silicone IOLs, when foldable IOL techniques are used it is likely that an acrylic polymer IOL would be advantageous for those patients at risk for future vitreous procedures requiring fluid-air exchange.

Animals↗
PubMed1996

Factors associated with visual acuity loss after noncontact transscleral Nd:YAG cyclophotocoagulation.

PURPOSE: To determine the factors associated with visual acuity loss following transscleral Nd:YAG cyclophotocoagulation (TYC). METHODS: The authors retrospectively studied 479 patients followed for a mean of 22 months after the initial TYC in one eye and analyzed the data with univariate and multivariate analysis for the factors associated with visual acuity loss. Data analyzed included age, race, sex, preoperative intraocular pressure (IOP) and visual acuity, type of glaucoma, total energy per treatment, number of retreatments, final IOP, and duration of follow-up. RESULTS: The preoperative factors associated with visual acuity loss after TYC as determined by both univariate and multivariate analysis were neovascular glaucoma (p = 0.001, odds ratio = 2.80) and black race (p = 0.044, odds ratio = 1.67). Postoperative hypotony and follow-up of > 6 months were also associated with visual acuity loss (p < 0.001, odds ratio = 6.68 and p = 0.046, odds ratio = 2.61, respectively). CONCLUSIONS: Transscleral Nd:YAG cyclophotocoagulation is associated with a greater risk of visual acuity loss in patients with neovascular glaucoma and in the black population. Postoperative hypotony is associated with a poor visual outcome, whereas the association with longer follow-up duration suggests that other factors, related to the patient's underlying disease, are also significant factors.

Adolescent↗