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Volume 3, Number 31
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Monday, August 4, 2003
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| Optic Neuritis
and the Risk of Multiple Sclerosis: A 10-Year Study Results of the Optic Neuritis Study, aimed at identifying factors associated with risk levels for multiple sclerosis (MS) after an initial episode of optic neuritis, shows that the 10-year risk is significantly higher if the patient has a single brain magnetic resonance imaging (MRI) lesion. Higher numbers of lesions do not appreciably increase that risk, but even when brain lesions do show on MRI, more than 40 percent of patients will not develop clinical MS after 10 years. The George Washington University Biostatistics Center, Rockville, MD, served as the data coordinating center for the Optic Neuritis Treatment Trial (ONTT), a randomized, distributed data entry clinical trial of 457 patients to evaluated the benefit of corticosteroid treatment of optic neuritis and to investigate the relationship between optic neuritis and multiple sclerosis. The study's structure consisted of 15 clinical centers and three central units: Study Headquarters, Data Coordinating Center and Visual Field Reading Center. The trial established that intravenous methylprednisolone sped recovery of visual function without significantly improving long-term visual outcomes and was also associated with a reduced incidence of symptomatic multiple sclerosis; oral prednisone not only failed to demonstrate any benefit compared to placebo, but it was also further associated with an increased risk of recurrence of optic neuritis (New Eng J Med 1992;326:9 and New Eng J Med 1993;329:24). In the present study, members of the ONTT group followed up on 388 patients who experienced acute optic neuritis between July 1, 1988, and June 30, 1991, for the development of multiple sclerosis. Consenting patients were reassessed after 10 to 13 years. Results showed that the 10-year risk of multiple sclerosis was 38 percent (95 percent confidence interval, 33 to 43 percent). Some 160 patients who had one or more typical lesions on a baseline MRI brain scan had a 56 percent risk; 191 who had no lesions had a 22 percent risk. Among the patients who had no lesions on MRI, male gender and optic disc swelling were associated with a lower risk of multiple sclerosis, as was the presence of the following atypical features for optic neuritis: no light perception vision; absence of pain; and ophthalmoscopic findings of severe optic disc edema, peripapillary hemorrhages or retinal exudates. In the absence of MRI lesions, certain demographic and clinical features seem to predict a very low likelihood of developing multiple sclerosis. This natural history information is a critical input for estimating a patient's 10-year multiple sclerosis risk and for weighing the benefit of initiating prophylactic treatment at the time of optic neuritis or other initial demyelinating events in the central nervous system. |
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SOURCE: Beck RW, Trobe JD, Moke PS, et al (Optic Neuritis Study Group). High- and low-risk profiles for the development of multiple sclerosis within 10 years after optic neuritis: Experience of the Optic Neuritis Treatment Trial. Arch Ophthalmol 2003;121(7):944-9. |
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| Altered Control
of Visual Fixation and Saccadic Eye Movements with ADHD Attention-deficit hyperactivity disorder (ADHD) patients may have a reduced ability to suppress unwanted saccades and control their fixation behavior voluntarily, according to a study by Canada’s Centre for Neuroscience Studies at Queen’s University, Ontario. The finding, which is consistent with a frontostriatal pathophysiology, is discussed in the context of recent neurophysiological data from nonhuman primates that have identified important control signals for saccade suppression that emanate from frontostriatal circuits. ADHD is characterized by the overt symptoms of impulsiveness, hyperactivity and inattention. A frontostriatal pathophysiology has been hypothesized to produce these symptoms and lead to reduced ability to inhibit unnecessary or inappropriate behavioral responses. Oculomotor tasks can be designed to probe the ability of subjects to generate or inhibit reflexive and voluntary responses. Because regions of the frontal cortex and basal ganglia have been identified in the control of voluntary responses and saccadic suppression, the authors of this study hypothesized that children and adults diagnosed with ADHD may have specific difficulties in oculomotor tasks requiring the suppression of reflexive or unwanted saccadic eye movements. The researchers measured eye movement performance in pro- and anti-saccade tasks of 114 ADHD and 180 control participants ranging from 6 to 59 years old. In the pro-saccade task, participants were instructed to look from a central fixation point toward an eccentric visual target. In the anti-saccade task, stimulus presentation was identical, but participants were instructed to suppress the saccade to the stimulus and instead look from the central fixation point to the side opposite the target. Researchers manipulated the state of fixation by presenting the target either when the central fixation point was illuminated (overlap condition) or at some time after it disappeared (gap condition). In the pro-saccade task, ADHD participants had longer reaction times, greater intra-subject variance, reduced peak velocities and increased duration of their saccades. In the anti-saccade task, ADHD participants had greater difficulty suppressing reflexive pro-saccades toward the eccentric target, increased reaction times for correct anti-saccades and greater intra-subject variance. In a third task requiring prolonged fixation, ADHD participants generated more intrusive saccades during periods when they were required to maintain steady fixation. |
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SOURCES: Munoz DP, Armstrong IT, Hampton KA, Moore KD. Altered control of visual fixation and saccadic eye movements in attention-deficit hyperactivity disorder. J Neurophysiol 2003;90(1):503-14. |
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| Long-term Observation
of Aqueous Flare Following Penetrating Keratoplasty A study aimed at understanding the influence of preoperative corneal conditions, combined implant surgeries and subsequent rejection on the aqueous flare value following penetrating keratoplasty (PK) showed that preoperative diagnoses and additional implant surgeries in PK patients influence the aqueous flare counts at the early postoperative period, while persistently elevated flare value may be associated with later rejection. Researchers from Taiwan’s Chang Gung University included 86 eyes of 86 patients in the study. PK alone was performed on seven eyes with keratoconus, 19 eyes with corneal scar from previous trauma or nonherpetic infection, 16 with pseudophakic bullous keratopathy (PBK), and 14 for regraft. Surgeons performed combined extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC-IOL) implantation (triple procedure) on 17 eyes with corneal scar, and performed combined anterior chamber (AC)-IOL exchange on 13 eyes with PBK. They measured aqueous flare with a laser flare-cell meter at one week and one, three, six, 12, and 24 months postoperatively. The mean follow-up was 24.7 (range 7 to 76) months. Results showed 11 cases (12.8 percent) of endothelial rejection (two in PK for corneal scar group, two in triple procedure group, two in PK for PBK group, three in PK and AC-IOL exchange group and two in regraft group). Two corneas in PK for corneal scar group, one in PK and AC-IOL exchange group and one in regraft group cleared up later; the remaining seven cases failed subsequently. Another 10 grafts (11.6 percent) failed from other causes. Eventually, 69 grafts (80.2 percent) remained clear at last follow-up. A significant difference in aqueous flare values was evident among eyes undergoing PK only for keratoconus, corneal scar, PBK and regraft from one week to three months postoperatively. In the corneal scar group, aqueous flare value was significantly higher from one week to three months when combined with cataract surgery. In the PBK group, the value was significantly higher from one week to one month, and six months again when combined with AC-IOL exchange. Notably, significantly higher flare values were measured from one week to six months in eyes with later rejection. |
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SOURCE: Ma D H-K, See L-C, Chen J J-Y. Long-term observation of aqueous flare following penetrating keratoplasty. Cornea 2003;22(5):413-9. |
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| Fentanyl Before
Retrobulbar Anesthesia for Cataract Surgery A Turkish study shows that systemic fentanyl analgesia may be effective in preventing the pain related to the administration of retrobulbar anesthesia and cataract surgery. In a single-blind randomized study, researchers evaluated 120 patients with American Society of Anesthesiologists physical status I to III scheduled for cataract surgery. Patients with a history of hypertension, hyperthyroidism or neurologic or psychiatric disorders were excluded. In the study (fentanyl) group (60 patients), an intravenous bolus of fentanyl 2µ g/kg was slowly administered five minutes before retrobulbar anesthesia was administered. The control group (60 patients) did not receive fentanyl. Demographic data were not statistically different between the two groups. Researchers measured the intensity of pain during injection and intraoperatively by verbal pain scores, and assessed hemodynamic stability by the heart rate (HR) and mean arterial pressure (MAP). They also recorded end-tidal carbon dioxide concentrations and oxygen saturations. Results showed that changes in HR and MAP at zero, 10, 20 and 30 minutes were statistically significant between the fentanyl and control groups. Fentanyl reduced pain scores significantly at all evaluations. The results suggest that fentanyl preemptively decreases injection and intraoperative hyperalgesia and provides hemodynamic stability without affecting patient cooperation. This results in cataract surgery with retrobulbar anesthesia that is comfortable for both surgeon and patient. |
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SOURCE: Inan UU, Sivaci RG, Ermis SS, et al. Effects of fentanyl on pain and hemodynamic response after retrobulbar block in patients having phacoemulsification. J Cataract Refract Surg 2003;29:1137-42. |
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| Early Surgery
for Acute Macular Pucker Patients with acute macular pucker have precipitous visual loss caused by epiretinal membrane formation after retinal tear or detachment, and early surgery can bring rapid recovery of visual acuity and resolution of metamorphopsia, according to a retrospective interventional noncomparative case series by London’s Moorfields Eye Hospital. The study included five patients with rapidly progressive visual loss and metamorphopsia over two weeks to three months, secondary to macular pucker after retinal tears or detachment. Surgeons performed vitrectomy and epiretinal membrane removal within one month of diagnosis. In the absence of complications, patients had rapid recovery of visual acuity with resolution of metamorphopsia within six weeks to three months. Surgical complications limited the visual outcome in two cases. Histopathologic examination of epiretinal membrane removed from two of the cases suggests that these tend to form tubuloacinar structures and contain more retinal pigment epithelium-derived cells than tissue excised from cases with idiopathic macular pucker. The clinical features and comparative immunohistochemistry of acute macular pucker suggest that it is a distinct clinicopathologic entity. |
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SOURCE: Sheard RM, Sethi C, Gregor Z. Acute macular pucker. Ophthalmol 2003;110(6):1178-84. |
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BRIEFLY
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OPHTHALMIC
IMAGING SYSTEMS AND NEXTGEN SIGN LICENSING AGREEMENT.
EUROPEAN
COMMISSION APPROVES U.S. FACILITY FOR FABRY’S DRUG.
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