PubMed Health⌕ Search

Biomedical subjects

Thomas R Friberg

Publications and source records attributed to Thomas R Friberg.

11 recordsLinked to original sources
PubMed2006

Prophylactic treatment of age-related macular degeneration report number 1: 810-nanometer laser to eyes with drusen. Unilaterally eligible patients.

OBJECTIVE: To determine the effects of subthreshold 810-nm-diode laser treatment on the rate of development of choroidal neovascularization (primary end point) and the effect on visual acuity (VA) in participants with multiple large drusen in one eye and a preexisting neovascular age-related macular degeneration (AMD) lesion in the other. DESIGN: Multicenter, prospective, randomized controlled trial. PARTICIPANTS: Two hundred forty-four patients > or =50 years of age and with a neovascular or advanced AMD lesion in one eye and, in the fellow "study" eye, (1) at least 5 drusen > or = 63 mum in diameter, (2) Early Treatment Diabetic Retinopathy Study best-corrected VA (BCVA) of 20/63 or better, and (3) no evidence of neovascularization at baseline. METHODS: Patients were randomized to treatment or observation of their study eye at each of 22 centers. At each visit, the protocol specified that BCVA, a complete retinal examination, and fluorescein angiography be documented. Treated eyes had a grid of 48 extrafoveal, subthreshold diode (810 nm) laser spots, 125 mum in diameter, placed in an annulus outside of the foveola. Patients were seen at baseline and at 3, 6, 12, 18, 24, 30, and 36 months after randomization. No retreatments were allowed. MAIN OUTCOME MEASURES: Development of choroidal neovascularization (as confirmed by fluorescein angiography) and change in BCVA. RESULTS: Throughout follow-up, the rate of choroidal neovascularization events in treated eyes consistently exceeded that in observed eyes. At 1 year, the difference was 15.8% versus 1.4% (P = 0.05). Most of the intergroup differences in choroidal neovascularization events occurred during the first 2 years of follow-up. Treated eyes showed a higher rate of VA loss (> or =3 lines) at 3- and 6-month follow-ups relative to observed eyes (8.3% vs. 1% and 11.4% vs. 4%, respectively; Ps = 0.02, 0.07). After 6 months, no significant differences were observed in VA loss between groups. CONCLUSION: Prophylactic subthreshold 810-nm-diode laser treatment to an eye with multiple large drusen in a patient whose fellow eye has already suffered a neovascular event places the treated eye at higher risk of developing choroidal neovascularization. We advise against using prophylactic subthreshold diode laser treatment in these eyes.

Aged↗
PubMed2004

Retinal detachment associated with macular hole in high myopia: using the vitreous anatomy to optimize the surgical approach.

PURPOSE: To evaluate the efficacy of different surgical strategies on the postoperative outcomes of retinal detachments (RDs) associated with macular holes (MHs) in high myopia. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: The study included 120 phakic, highly myopic eyes (mean degree of myopia, -22.2+/-4.80 diopters) with RDs and MHs that underwent surgical repair. The patients were divided into 2 groups. Group 1 consisted of 60 eyes with a posterior vitreous detachment (PVD). Mean preoperative visual acuity (VA) was 20/200+/-20/500. Group 2 consisted of 60 eyes with posterior vitreous schisis (PVS). The mean preoperative VA was 20/152+/-20/333. The minimum follow-up was 6 months. INTERVENTION: The surgical approach was chosen on the basis of the clinical characteristics. Twenty-five eyes of group 1 underwent pneumoretinopexy (group 1A), whereas 35 eyes of group 1 were repaired with vitrectomy (group 1B). Forty-nine eyes of group 2 underwent pars plana vitrectomy (group 2A), whereas 11 eyes of group 2 underwent scleral buckling of the macula (group 2B). MAIN OUTCOME MEASURES: Anatomic attachment of the retina and VA. RESULTS: Retinal reattachment at 6 months was achieved in 23 of 25 (92%) eyes of group 1A, 31 of 35 (88.5%) eyes of group 1B, 45 of 49 (91.8%) eyes of group 2A, and 8 of 11 (72.7%) eyes of group 2B. A significant (P<0.01) improvement of postoperative VA with respect to the preoperative values was observed in all groups. The greatest percentage improvement in postoperative VA was observed in groups 1A and 1B eyes. CONCLUSIONS: Different surgical approaches can be used to repair myopic RD associated with an MH. The choice between different surgical techniques may depend on vitreoretinal relationships, the extent of chorioretinal atrophic areas, and presence of posterior staphyloma. In our study, eyes with a PVD had significantly better visual outcomes than detachments in eyes with PVS.

Adult↗
PubMed2003

Interactions of perfluorocarbon liquids and silicone oil as characterized by mass spectrometry.

BACKGROUND: Perfluorocarbon liquids (PFCL) are used extensively in complex vitreoretinal surgery, sometimes before the placement of silicone oil (SiO). We suspected that PFCL and SiO interact physically when in opposition, potentially making their removal more difficult. The nature of some of these interactions was explored using a mass spectrometric approach in in-vitro and in-vivo samples. METHODS: We incubated silicone oil (1,000 or 5,000 centistokes viscosity) and PFCL [perfluoro-n-octane (PFO) or perfluorotributylamine] together in vitro for 6 months and performed electron impact ionization mass spectrometry (EIMS) on the PFCL to characterize interactions between the liquid phases. Packaged samples of PFCL served as controls. We also examined in vivo samples of PFO which had been retained in human eyes for several months prior to surgical removal. RESULTS: Perfluorocarbon liquids packaged for surgical use all contain SiO in trace amounts, possibly as a manifestation of the processes used in their manufacture. Furthermore, all PFCLs incubated with SiO showed much more prominent contamination with SiO molecular fragments. PFCL was found in the SiO phase of eyes in which both liquids were present for extended periods of time. The EIMS analysis of in vivo samples suggested that proteins coat PFCL droplets, forming micelle-like structures. CONCLUSION: Medical-grade PFCLs contain small amounts of SiO, and PFCLs dissolve small amounts of oil into solution over time. Interactions between retained vitreous substitutes may have clinical relevance.

Drug Interactions↗
PubMed2003

Frequency of epithelial debridement during diabetic vitrectomy.

PURPOSE: To survey active vitreoretinal surgeons to determine how often they intentionally debride the corneal epithelium during vitrectomy surgery for diabetic patients and to ascertain whether the selection of the surgical lens type influences the debridement rate. DESIGN: Observational retrospective case series. METHODS: Fifty-five vitreoretinal surgeons were asked to retrospectively report how many pars plana vitrectomies they performed in 1 year on diabetic eyes and in what percent of the cases was debridement of the cornea necessary. In a second query, they were asked to note which specific type of surgical lens system (hand-held irrigating, Landers sew-on, or Oculus BIOM noncontact) was used for their surgical intervention. RESULTS: The total number of diabetic vitrectomies performed in 1 year by the respondents was 8,002. The frequency of epithelial debridement was 17.4%, with a range of 0% to 90%. The use of irrigating contact lenses was associated with a significantly higher rate of debridement compared with the use of sew-on or BIOM noncontact lenses (23.5% vs 12.1%, P <.001). Regarding the 41 surgeons who indicated a specific type of lens used, we found that the debridement rate for infusion lenses was 23.8% compared with 13.0% for sew-on lenses and 15.6% for noncontact BIOM lenses. The difference between these groups was statistically significant (P <.025). CONCLUSIONS: Irrigating contact lenses appear to increase the need for epithelial debridement compared with other alternatives. Sew-on lenses with a viscoelastic cushion may provide the best corneal protection.

Debridement↗
PubMed2003

Topical phenylephrine may result in worsening of visual loss when used to dilate pupils in patients with vaso-occlusive disease of the optic nerve.

Four patients (age range 54-82, 1F 3M) diagnosed with non-arteritic ischemic optic neuropathy experienced acute worsening of visual function after instillation of phenylephrine for dilated funduscopic examination. They experienced decreased visual function immediately or shortly after administration of topical mydriatic drops given in preparation for funduscopy. In all cases one drop each of 2.5% phenylephrine and 0.5-1% tropicamide was used. Three patients had classical risk factors such as hypertension, diabetes, and had a contralateral "disc-at-risk". The female and youngest patient had ischemic optic neuropathy presumed secondary to lupus erythematosus. The time from acute visual loss to presentation to neuro-ophthalmic care ranged from 1-6 days. The time of onset of the decline in visual function varied from 45 minutes (patient with lupus) to 12 hours after instillation of mydriatic drops. Visual acuity at diagnosis ranged from 20/40-20/400. Phenylephrine is a mydriatic with vasoconstrictive properties, which may be absorbed through the cornea, thus yielding non-negligible intraocular concentrations. Vasoconstriction of the watershed posterior ciliary capillary beds may result in further precipitating infarction of already compromised circulatory territories in edematous optic nerves. Because phenylephrine is a known vasoconstrictor in vivo and in vitro, it is more likely to cause deleterious vasoconstriction and an acute decline in visual function in patients with acute ischemic optic neuropathy than tropicamide. The routine practice of using phenylephrine to prepare patients for funduscopic assessment should be re-examined, particularly in patients with ischemic optic neuropathy.

Administration, Topical↗
PubMed2002

Choroidal neovascularization in primary hyperoxaluria.

PURPOSE: To report a case of primary hyperoxaluria in which choroidal neovascularization developed bilaterally. DESIGN: Observational case report. METHODS: A 22-year-old man with a history of type I primary hyperoxaluria complained of a slow but progressive loss of vision in both eyes for the preceding 8 months. The clinical, fluorescein, and ocular coherence tomography findings are reported. RESULTS: Fluorescein angiography confirmed the presence of choroidal neovascularization in both eyes at the edge of previous macular scars. Ocular coherence tomography scans were obtained to better characterize the clinical pathology. CONCLUSION: In a patient with type 1 primary hyperoxaluria, the presence of choroidal neovascularization in both eyes outside but adjacent to an area of previous macular scarring is reported. These findings are in harmony with the assumption that mechanical factors from the oxalate deposition promote choroidal neovascularization.

Adult↗
PubMed2002

Predictors of drusen reduction after subthreshold infrared (810 nm) diode laser macular grid photocoagulation for nonexudative age-related macular degeneration.

PURPOSE: To determine the predictors of drusen reduction in eyes with nonexudative age-related macular degeneration (ARMD) treated with subthreshold infrared (810 nm) diode laser macular grid photocoagulation. Additionally, to determine the relationship of laser-induced drusen reduction and best-corrected visual acuity (BCVA) 18 months after laser treatment. DESIGN: Randomized controlled clinical trial. METHODS: Fifty patients (100 eyes) with bilateral nonexudative ARMD were enrolled at two centers. One eye of each patient was randomized to the observation; the other eye was treated with 48 subthreshold (invisible end point) applications of infrared (810 nm) diode laser in a macular grid pattern. The eyes that received subthreshold laser treatment were compared with the eyes that received no treatment. The baseline fundus characteristics (number, size, and distribution of drusen, as well as focal hyperpigmentation) from two macula areas (central 1500 micro diameter, pericentral 1500 micro ring area) on stereo color photographs, the number of laser-induced lesions, and the area of laser induced retinal pigment epithelial (RPE) lesions on fluorescein angiography 3 months after treatment were studied as predictors of major drusen reduction (> or = 50% drusen reduction from baseline) 18 months after laser treatment. BCVA at baseline and 18 months later was compared in observation eyes and in laser-treated eyes. RESULTS: Eighteen months after randomization, 24 (48%) of 50 eyes treated with subthreshold laser had major drusen reduction compared with three (6%) of 50 observation eyes (P =.00001). At 3 months post-treatment in laser-treated eyes with major drusen reduction, the mean number of laser-induced lesions on fluorescein angiography was 30.7 and the mean area of RPE change was 0.81 mm(2) compared with 14.8 laser-induced lesions and 0.35 mm(2) area of RPE change in eyes without major drusen reduction (P =.0001 and P =.0003, respectively). At baseline, fundus characteristics were not significantly different between observation eyes and laser-treated eyes or between the major drusen reduction group and the nonmajor drusen reduction group. At 18 months after treatment, BCVA was not significantly different in laser-treated eyes and in observation eyes. CONCLUSIONS: Subthreshold infrared (810 nm) diode laser macular grid photocoagulation in eyes with nonexudative ARMD significantly reduced drusen 18 months after laser treatment. Both the number of subthreshold laser lesions and the area of RPE changes visible on fluorescein angiography 3 months after treatment appeared to be predictors for major drusen reduction 18 months after treatment. However, it remains to be determined whether laser-induced drusen reduction is beneficial for visual acuity or reduces the incidence of choroidal neovascularization (CNV) in eyes with nonexudative ARMD.

Aged↗
PubMedDate not supplied

Migration of intravitreal silicone oil through a Baerveldt tube into the subconjunctival space.

A 28-year-old patient developed proliferative diabetic retinopathy with florid rubeosis iridis and ultimately required the placement of a Baerveldt tube to control his secondary glaucoma. Eighteen months later, he underwent a pars plana vitrectomy, scleral buckle, lensectomy, and membrane peeling to reattach a severe diabetic retinal detachment. Ultimately, some of the 5000 cs silicone oil migrated through the tube to the episcleral region under the plate of the Baerveldt device. The oil intermittently blocked the shunt, causing elevated intraocular pressure. Despite ultimate surgical removal of the oil from around the tube and plate, a substantial amount remained encapsulated in the subconjunctival space. Prevention of this complication includes placement of a short tube well anterior to the iris in the inferior portion of the anterior chamber.

Adult↗
PubMedDate not supplied

Non-mydriatic panoramic fundus imaging using a non-contact scanning laser-based system.

BACKGROUND AND OBJECTIVE: A non-contact scanning laser-based retinal imaging system produces a 200 degrees wide-field panoramic image of the fundus through the novel use of a large elliptical mirror. The authors investigated whether accurate diagnoses could be made from these images alone. PATIENTS AND METHODS: Images were obtained from both eyes of arbitrarily selected patients and were retrospectively reviewed by retinal specialists. Each physician made a diagnosis, suggested the follow-up interval, and determined whether any intervention was needed based solely on image review. Diabetic retinopathy was categorized as background retinopathy only, preproliferative retinopathy, maculopathy, and proliferative retinopathy. The results of the image review were then compared with the results of clinical examination, and the sensitivity and specificity of the review were calculated. RESULTS: The correct overall diagnosis was made by the two specialists in 87% and 77% of cases, respectively; the specificity and sensitivity each averaged 76%. Follow-up interval recommendations from image review matched those made on clinical examination in 86% of cases. Diabetic retinopathy was correctly identified as a general diagnosis with a sensitivity of 94% and the follow-up recommendations corresponded to the clinical recommendations in 82%. Sixty-two percent of the images were judged to be of good quality or better, with only 6.4% deemed unreadable. Iris color did not influence image quality. CONCLUSION: The non-contact scanning laser-based retinal imaging system provides images of sufficient resolution and clarity to make accurate general diagnoses in a high percentage of cases. Its use as a screening device for specific diseases is feasible and merits further study.

Diagnostic Imaging↗