Biomedical subjects

Michael J Lynn

Publications and source records attributed to Michael J Lynn.

12 recordsLinked to original sources

PubMed2006

Impact of metabolic syndrome on prognosis of symptomatic intracranial atherostenosis.

BACKGROUND: The metabolic syndrome (MetS) is a cluster of risk factors linked to insulin resistance that increase an individual's risk of atherosclerotic vascular disease. The authors evaluated the prevalence and prognosis of the MetS among individuals with symptomatic intracranial arterial stenosis. METHODS: Patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease trial were evaluated in this post-hoc analysis. Baseline characteristics and outcome were compared in patients with the MetS vs patients without the MetS. RESULTS: Among 476 patients, the prevalence of the MetS was 43%. MetS patients were more likely to be younger, female, and white. During a mean follow-up period of 1.8 years, time to the first of ischemic stroke, myocardial infarction, or vascular death was shorter among patients with the MetS with a hazard ratio (syndrome/no syndrome) of 1.6 (95% CI = 1.1 to 2.4, p = 0.0097). Time to ischemic stroke alone was also shorter among patients with the MetS with a hazard ratio (syndrome/no syndrome) of 1.7 (95% CI = 1.1 to 2.6, p = 0.012). When controlling for individual factors of the definition, MetS was not significant (combined outcome: p = 0.14; ischemic stroke: p = 0.074). CONCLUSIONS: The metabolic syndrome is present in about half of individuals with symptomatic intracranial atherosclerotic disease and is associated with a substantially higher risk of major vascular events. The metabolic syndrome may not provide additional ability to predict outcomes beyond the individual factors for patients with intracranial stenosis.

Aged↗

PubMed2006

Predictors of ischemic stroke in the territory of a symptomatic intracranial arterial stenosis.

BACKGROUND: Antithrombotic therapy for intracranial arterial stenosis was recently evaluated in the Warfarin versus Aspirin for Symptomatic Intracranial Disease (WASID) trial. A prespecified aim of WASID was to identify patients at highest risk for stroke in the territory of the stenotic artery who would be the target group for a subsequent trial comparing intracranial stenting with medical therapy. METHODS AND RESULTS: WASID was a randomized, double-blinded, multicenter trial involving 569 patients with transient ischemic attack or ischemic stroke due to 50% to 99% stenosis of a major intracranial artery. Median time from qualifying event to randomization was 17 days, and mean follow-up was 1.8 years. Multivariable Cox proportional hazards models were used to identify factors associated with subsequent ischemic stroke in the territory of the stenotic artery. Subsequent ischemic stroke occurred in 106 patients (19.0%); 77 (73%) of these strokes were in the territory of the stenotic artery. Risk of stroke in the territory of the stenotic artery was highest with severe stenosis > or =70% (hazard ratio 2.03; 95% confidence interval 1.29 to 3.22; P=0.0025) and in patients enrolled early (< or =17 days) after the qualifying event (hazard ratio 1.69; 95% confidence interval 1.06 to 2.72; P=0.028). Women were also at increased risk, although this was of borderline significance (hazard ratio 1.59; 95% confidence interval 1.00 to 2.55; P=0.051). Location of stenosis, type of qualifying event, and prior use of antithrombotic medications were not associated with increased risk. CONCLUSIONS: Among patients with symptomatic intracranial stenosis, the risk of subsequent stroke in the territory of the stenotic artery is greatest with stenosis > or =70%, after recent symptoms, and in women.

Aged↗

PubMed2006

Is there a latent period for the surgical treatment of children with dense bilateral congenital cataracts?

BACKGROUND: It generally is accepted that cataract surgery during the first 6 weeks of life is associated with the best visual outcomes for children with dense unilateral congenital cataracts. The latent period for children with dense bilateral congenital cataracts has not been clearly defined. METHODS: The best-corrected visual acuity (BCVA) at 4 to 6 years of age was collected retrospectively on a series of 43 children with dense bilateral congenital cataracts from 4 institutions. All of the children underwent a lensectomy, posterior capsulotomy, and anterior vitrectomy at 36 weeks of age or younger. RESULTS: Cataract surgery was performed at a mean age of 11.5 weeks for the better-seeing eye. BCVA was assessed when the children were a mean of 5.3 years of age. The visual acuities of 26 (60%) were 20/40 or better, 12 (28%) were 20/50 to 20/80, and 5 (12%) were 20/100 or worse. There was a trend for worse BCVA with increasing age at the time of surgery (r = 0.28, P = 0.07). We noted that a BCVA of 20/100 or worse occurred only among eyes undergoing surgery when infants were older than 10 weeks ( 10 weeks: 5/22 = 23%, P = 0.049). Children with preoperative nystagmus had worse visual outcomes; only 38% of children with preoperative nystagmus achieved a BCVA of 20/40 or better compared with 74% of children without preoperative nystagmus (P = 0.03). CONCLUSION: Previous reports have proposed that cataract surgery during the first 5 to 8 weeks of life is associated with better visual outcomes in children with dense bilateral congenital cataracts. Our results would suggest that good visual outcomes can be achieved beyond this age, but the incidence of poor visual outcomes increases if cataract surgery is delayed beyond 10 weeks of age. The absence of preoperative nystagmus is a better predictor of a good visual outcome than the age at surgery.

Age Factors↗

PubMed2006

Pediatric homonymous hemianopia.

INTRODUCTION: Homonymous hemianopia is a disabling condition caused by numerous lesions affecting the retrochiasmal visual pathways. Little is known about homonymous hemianopia in childhood. METHODS: All patients seen in the Neuro-Ophthalmology Unit at Emory University with homonymous hemianopia (confirmed by Goldmann, Humphrey, or confrontation visual fields) between 1989 and 2004 were included. Demographic characteristics, clinical features, and evolution of the visual field defects were compared between the pediatric group (18 years of age or younger) and the adult group (older than 18 years). RESULTS: Among 852 patients with homonymous hemianopia, there were 81 children (86 homonymous hemianopias) and 771 adults (818 homonymous hemianopias). Formal visual field testing was obtained in 93% of pediatric cases and 96% of adults; a majority of patients in both groups were evaluated with Goldmann visual field testing. Demographic and visual field characteristics were similar in both groups. Significant differences were noted for the causative lesions and their location. Traumatic brain injury (34%) and tumor (27%) were the most common causes of homonymous hemianopia in the pediatric group, whereas infarction (63%), traumatic brain injury (12%), and hemorrhage (11%) were the most common causes in the adult group. Most lesions involved the optic radiations (37%), followed by the occipital lobes (26%), in the pediatric group, whereas occipital lobes (47%), followed by optic radiations (32%), were most commonly involved in adults. Approximately one third of the pediatric patients were seen in follow-up, and one third of these homonymous hemianopias spontaneously improved over the course of time. Of the 16 pediatric homonymous hemianopias evaluated within 1 month of onset of the cerebral disorder, 8 (50%) improved. CONCLUSION: Trauma and tumors are the most common cause of homonymous hemianopia in childhood. Although spontaneous improvement can be expected in approximately one third to one half of patients within the first few months, the recognition of homonymous hemianopia frequently is delayed in this population.

Adolescent↗

PubMed2006

Vitreous hemorrhage in children.

PURPOSE: To describe the presentations, etiologies, and visual outcomes of spontaneous and traumatic vitreous hemorrhage in children. DESIGN: Retrospective case series of patients seen over 8 consecutive years. PARTICIPANTS: One hundred sixty-eight patients (186 eyes), younger than 18 years, with vitreous hemorrhage not secondary to active retinopathy of prematurity (ROP). METHODS: Charts were reviewed and data were compiled with special attention to demographic information, diagnosis, examination findings, visual acuity (VA) on presentation and last follow-up, treatment type, and length of follow-up. MAIN OUTCOME MEASURES: Etiologies, presenting symptoms, initial and final VAs, and management modalities. RESULTS: Among 168 patients (186 eyes), the most common presenting symptom was decreased VA in older patients and strabismus and nystagmus in younger patients. Seventy-three percent of cases occurred secondary to manifest and occult trauma, with blunt (29.6%) and penetrating (24.7%) trauma being most common. Twenty-seven percent of hemorrhages occurred spontaneously, with regressed ROP being most common. Of the cases, 90.5% were unilateral and 9.5% were bilateral. Shaken baby syndrome accounted for 50% of bilateral cases. The most common management modalities were observation (50.0%) and incisional surgery (45.7%), but frequency of management modality varied by etiology. Visual outcomes, which were limited by variable follow-up and nonstandardized acquisition, were poorest with penetrating trauma and best with regressed ROP. There was no statistical difference in severe vision loss between children older than 8 years and younger than 8. CONCLUSIONS: Pediatric vitreous hemorrhage may have multiple etiologies, but manifest and occult trauma are most common. Regressed ROP is a common cause of spontaneous vitreous hemorrhage. A substantial proportion of patients with vitreous hemorrhage had severe vision loss, but outcomes were highly dependent on underlying etiology.

Adolescent↗

PubMed2006

Homonymous hemianopia in stroke.

BACKGROUND: Previous reports have suggested that most cases of homonymous hemianopia (HH) are caused by occipital stroke. However, these reports have not always been supported by brain imaging. METHODS: We reviewed the medical records of all patients seen in our unit between 1989 and 2004 who had HH documented by formal perimetry or confrontation visual fields and had undergone brain imaging. HHs were divided into those caused by stroke and by non-stroke conditions. The clinical and visual field characteristics were compared in the two groups. RESULTS: Among 850 patients with 902 HHs, 629 (69.7%) resulted from stroke, of which 531 (84.4%) were from infarction and 98 (15.6%) from primary intraparenchymal hemorrhage. Non-stroke causes included head trauma (123), brain tumor (102), neurosurgical procedures (22), multiple sclerosis (13), and miscellaneous conditions (13). Occipital lesions most commonly resulted from stroke. The configuration of the HH did not predict where in the retrochiasmal visual pathway the responsible lesion lay. CONCLUSIONS: Ischemic stroke causes most HHs from lesions in the occipital lobe that generally do not produce other neurologic manifestations. The configuration of the HH does not predict the location of the lesion within the retrochiasmal visual pathway.

Adolescent↗

PubMed2005

Comparison of warfarin and aspirin for symptomatic intracranial arterial stenosis.

BACKGROUND: Atherosclerotic intracranial arterial stenosis is an important cause of stroke. Warfarin is commonly used in preference to aspirin for this disorder, but these therapies have not been compared in a randomized trial. METHODS: We randomly assigned patients with transient ischemic attack or stroke caused by angiographically verified 50 to 99 percent stenosis of a major intracranial artery to receive warfarin (target international normalized ratio, 2.0 to 3.0) or aspirin (1300 mg per day) in a double-blind, multicenter clinical trial. The primary end point was ischemic stroke, brain hemorrhage, or death from vascular causes other than stroke. RESULTS: After 569 patients had undergone randomization, enrollment was stopped because of concerns about the safety of the patients who had been assigned to receive warfarin. During a mean follow-up period of 1.8 years, adverse events in the two groups included death (4.3 percent in the aspirin group vs. 9.7 percent in the warfarin group; hazard ratio for aspirin relative to warfarin, 0.46; 95 percent confidence interval, 0.23 to 0.90; P=0.02), major hemorrhage (3.2 percent vs. 8.3 percent, respectively; hazard ratio, 0.39; 95 percent confidence interval, 0.18 to 0.84; P=0.01), and myocardial infarction or sudden death (2.9 percent vs. 7.3 percent, respectively; hazard ratio, 0.40; 95 percent confidence interval, 0.18 to 0.91; P=0.02). The rate of death from vascular causes was 3.2 percent in the aspirin group and 5.9 percent in the warfarin group (P=0.16); the rate of death from nonvascular causes was 1.1 percent and 3.8 percent, respectively (P=0.05). The primary end point occurred in 22.1 percent of the patients in the aspirin group and 21.8 percent of those in the warfarin group (hazard ratio, 1.04; 95 percent confidence interval, 0.73 to 1.48; P=0.83). CONCLUSIONS: Warfarin was associated with significantly higher rates of adverse events and provided no benefit over aspirin in this trial. Aspirin should be used in preference to warfarin for patients with intracranial arterial stenosis.

Adult↗

PubMed2005

A comparison of 2 methods for estimating residual stromal bed thickness before repeat LASIK.

PURPOSE: To compare 2 methods of calculating residual stromal bed (RSB) thickness after repeat LASIK, to determine which method generates more conservative RSB thickness estimates, and to determine any factors related to the discrepancy between these 2 calculation methods. DESIGN: Retrospective nonrandomized comparative trial. PARTICIPANTS: Seventy-nine patients (one eye per patient) undergoing primary LASIK and 2 repeat procedures (second and third LASIK) from 1998 to 2002. METHODS: We compared calculated RSB thickness after second and third LASIK using either original corneal thickness (CT) minus flap thickness and all ablations (original CT method) or pre-enhancement CT minus flap thickness and enhancement ablation (repeat CT method). MAIN OUTCOMES MEASURES: Differences in calculated RSB thickness after second and third LASIK by each method. RESULTS: Calculated RSB thickness averaged 329 microm by the repeat CT method compared with 305 microm by the original CT method after second LASIK (mean difference, 24 microm; P<0.0001) and 320 microm by the repeat CT method compared with 289 microm by the original CT method after third LASIK (mean difference, 31 microm; P<0.0001). After second LASIK, for 54% of eyes the repeat CT method was greater by >or=20 microm, and for 19% of eyes it was greater by >or=40 microm. After third LASIK, for 67% of eyes the repeat CT method was greater by >or=20 microm, and for 26% of eyes it was greater by >or=40 microm. The repeat CT method gave greater RSB thickness values than the original CT method in 73 of 79 eyes (92%) after second LASIK and in 72 of 79 eyes (91%) after third LASIK. The difference between the 2 methods was not associated with age, gender, initial preoperative refractive error, or refractive error before repeat LASIK. CONCLUSION: Using original preoperative CT measurements provides a more conservative and thus safer approach than using CT measurements obtained before repeat LASIK to calculate RSB thickness after repeat LASIK.

Adult↗

PubMed2004

Surgical management of glaucoma in infants and children with Peters' anomaly: long-term structural and functional outcome.

OBJECTIVE: To determine the long-term outcome of surgery for congenital glaucoma in infants and children with Peters' anomaly. DESIGN: Retrospective review of a consecutive interventional case series. SETTING: An urban academic tertiary referral institution. PARTICIPANTS: Thirty-four eyes of 19 children are subjects of this report. Included are all children 12 years of age or younger with Peters' anomaly who underwent surgery for primary congenital glaucoma between January 1971 and December 1992 and completed a minimum of 3 years of follow-up from the date of the first glaucoma surgery. INTERVENTION: The surgical procedures performed were trabeculectomy, trabeculotomy, goniotomy, Molteno shunt implantation, cyclodialysis, and cyclocryotherapy. MAIN OUTCOME MEASURES: Primary outcome measures were intraocular pressure (IOP) control and final postoperative visual acuity. Intraocular pressure control was defined as complete success (IOP</=21 mmHg without antiglaucoma medication), qualified success (IOP</=21 mmHg with antiglaucoma mediation), or failure (IOP>21 mmHg with or without antiglaucoma medication, inoperable retinal detachment, phthisis, or chronic hypotony, defined as an IOP of </=6 mmHg). RESULTS: A total of 126 glaucoma procedures were performed on 34 eyes of 19 patients. The median age at time of first glaucoma surgery was 2.1 months (range, 2 days to 8.5 years). The median follow-up was 11.0 years (range, 3.2 to 22.8 years) from the time of first glaucoma surgery. Intraocular pressure control with or without antiglaucoma medication was achieved in 11 eyes (32%) after 1 or more surgical procedures. Major postoperative complications included graft failure in 26 eyes (76%), cataract in 6 eyes (18%), inoperable retinal detachment with phthisis in 12 eyes (35%), and phthisis alone in 6 eyes (18%). Final vision was 20/200 or better in 3 eyes (9%), 20/400 to hand motion in 12 eyes (35%), light perception in 7 eyes (21%), and no light perception in 12 eyes (35%). CONCLUSIONS: Glaucoma surgery, combined with medical therapy, may result in adequate, long-term IOP control in 32% of eyes with glaucoma associated with Peters' anomaly. Visual results are poor due to uncontrolled glaucoma, amblyopia, neurologic impairment, and other anterior and posterior segment anomalies that may accompany Peters' anomaly. Postoperative complications, including graft failure, cataract, inoperable retinal detachment, and phthisis, also contribute to decreased visual acuity.

Child↗

PubMed2002

Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses.

Oxidative stress is a component of diseases and degenerative processes associated with aging. However, no means are available to assess causative oxidative events separately from decline in function of protective antioxidant systems. Previous studies show that ongoing oxidative processes maintain plasma cysteine/cystine redox at a value that is more oxidized than the antioxidant glutathione/glutathione disulfide (GSH/GSSG) system, suggesting that redox analysis of these plasma thiols could allow separate evaluation of an increase in oxidative events from a decline in antioxidant function. The present study uses measurement of cysteine/cystine and GSH/GSSG redox in plasma of 122 healthy individuals aged 19-85 years to determine whether thiol-disulfide redox changes occur with age. The results show a linear oxidation of cysteine/cystine redox state with age at a rate of 0.16 mV/year over the entire age span. In contrast, GSH/GSSG redox was not oxidized prior to 45 years and subsequently was oxidized at a nearly linear rate of 0.7 mV/year. These data suggest that there is a continuous, linear increase in oxidative events throughout adult life but that the capacity of the GSH antioxidant system is maintained until 45 years and then declines rapidly. The data further suggest that redox states of cysteine/cystine and GSH/GSSG provide an approach to clinically distinguish between increased causative oxidative events and decreased GSH antioxidant function. In principle, such analyses can be used to assess efficacy of intervention strategies against oxidative stress prior to or early after onset of clinical symptoms in aging and age-related disease.

Adolescent↗

PubMed2002

Clinical outcome of confluent laser photoablation for retinopathy of prematurity.

PURPOSE: During the past decade, laser photoablation has supplanted cryotherapy as the standard treatment for threshold retinopathy of prematurity (ROP). We evaluated the progression and the complication rate in a cohort of infants with threshold ROP treated with a confluent technique. METHODS: We retrospectively studied 47 patients with ROP (91 eyes), treated with confluent diode laser photoablation. Four main outcomes were evaluated: (1) the rate of progression, (2) the frequency of laser retreatment, (3) postoperative complications, and (4) postoperative refractive error. RESULTS: A mean of 1943 +/- 912 laser burns were administered in a confluent pattern to 91 eyes with threshold ROP. Progression to stage 4 or 5 disease occurred in 13 of 29 eyes (44.8%) with zone I and posterior zone II and in 2 of 51 eyes (3.9%) with anterior zone II ROP (P =.01). Eyes with anterior zone II ROP that received more than or equal to 2000 burns progressed more than those that received fewer than 2000 burns. Only 1 eye (1%) needed a supplemental laser treatment. Postoperative complications included corneal edema (2.3%), anterior segment ischemia (2.3%), vitreous hemorrhage (7.9%), posterior synechiae (2.3%), cataract (4.9%), and macular ectopia (12%). The mean spherical equivalent at the last follow-up was -4.52 +/- 5.63 D. CONCLUSIONS: In our series, infants received more laser burns than infants reported in the literature receiving scatter or near-confluent treatment. While confluent treatment almost eliminated supplemental treatment, it was associated with a similar rate of progression and complications as has been reported with other patterns of laser treatment.

Birth Weight↗

PubMed2002

Trabeculectomy with antiproliferative agents in uveitic glaucoma.

PURPOSE: To evaluate the outcome of trabeculectomy with antiproliferative agents in patients with uveitic glaucoma METHODS: A retrospective chart review of 44 eyes of 44 patients with uveitic glaucoma who underwent trabeculectomy with mitomycin C or 5-fluorouracil. The authors defined complete success as an intraocular pressure of 21 mm Hg or lower without pressure-lowering medications, qualified success as an intraocular pressure of 21 mm Hg or lower with medications, and failure as an intraocular pressure of more than 21 mm Hg with medications, loss of light perception, or the need for reoperation. RESULTS: The cumulative probability of complete or qualified success was 78% at 1 year and 62% at 2 years. At 2 years, success rates were 39% in males and 71% in females (P = 0.02), 74% in white patients and 55% in black patients (P = 0.58), and 45% in patients with idiopathic uveitis and 74% in patients with sarcoid uveitis (P = 0.17). Sixteen of 31 (51.6%) phakic patients developed new cataracts or had progression of existing cataracts and required cataract extraction. Four of 16 eyes (25%) lost intraocular pressure control and needed repeat trabeculectomy after undergoing cataract surgery. CONCLUSIONS: Patients with uveitic glaucoma can have good outcomes after trabeculectomy with antiproliferative agents. Male gender was the only statistically significant risk factor for trabeculectomy failure. Cataract management in the presence of a filtering bleb poses a treatment dilemma between improvement of visual acuity and loss of intraocular pressure control.

Adolescent↗