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Extraocular muscles in patients with infantile nystagmus: adaptations at the effector level.

To test the hypothesis that the extraocular muscles (EOMs) of patients with infantile nystagmus have muscular and innervational adaptations that may have a role in the involuntary oscillations of the eyes. Specimens of EOMs from 10 patients with infantile nystagmus and postmortem specimens from 10 control subjects were prepared for histologic examination. The following variables were quantified: mean myofiber cross-sectional area, myofiber central nucleation, myelinated nerve density, nerve fiber density, and neuromuscular junction density. In contrast to control EOMs, infantile nystagmus EOMs had significantly more centrally nucleated myofibers, consistent with cycles of degeneration and regeneration. The EOMs of patients with nystagmus also had a greater degree of heterogeneity in myofiber size than did those of controls, with no difference in mean myofiber cross-sectional area. Mean myelinated nerve density, nerve fiber density, and neuromuscular junction density were also significantly decreased in infantile nystagmus EOMs. The EOMs of patients with infantile nystagmus displayed a distinct hypoinnervated phenotype. This represents the first quantification of changes in central nucleation and myofiber size heterogeneity, as well as decreased myelinated nerve, nerve fiber, and neuromuscular junction density. These results suggest that deficits in motor innervation are a potential basis for the primary loss of motor control. Improved understanding of the etiology of nystagmus may direct future diagnostic and treatment strategies.

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Evaluation of visual acuity measurements after autorefraction vs manual refraction in eyes with and without diabetic macular edema.

To compare visual acuity (VA) scores after autorefraction vs manual refraction in eyes of patients with diabetes mellitus and a wide range of VAs. The letter score from the Electronic Visual Acuity (EVA) test from the electronic Early Treatment Diabetic Retinopathy Study was measured after autorefraction (AR-EVA score) and after manual refraction (MR-EVA score), which is the research protocol of the Diabetic Retinopathy Clinical Research Network. Testing order was randomized, study participants and VA examiners were masked to refraction source, and a second EVA test using an identical supplemental manual refraction (MR-EVAsuppl score) was performed to determine test-retest variability. In 878 eyes of 456 study participants, the median MR-EVA score was 74 (Snellen equivalent, approximately 20/32). The spherical equivalent was often similar for manual refraction and autorefraction (median difference, 0.00; 5th-95th percentile range, -1.75 to 1.13 diopters). However, on average, the MR-EVA scores were slightly better than the AR-EVA scores, across the entire VA range. Furthermore, the variability between the AR-EVA scores and the MR-EVA scores was substantially greater than the test-retest variability of the MR-EVA scores (P < .001). The variability of differences was highly dependent on the autorefractor model. Across a wide range of VAs at multiple sites using a variety of autorefractors, VA measurements tend to be worse with autorefraction than manual refraction. Differences between individual autorefractor models were identified. However, even among autorefractor models that compare most favorably with manual refraction, VA variability between autorefraction and manual refraction is higher than the test-retest variability of manual refraction. The results suggest that, with current instruments, autorefraction is not an acceptable substitute for manual refraction for most clinical trials with primary outcomes dependent on best-corrected VA.

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Open Access
Presumed solitary circumscribed retinal astrocytic proliferation: the 2010 Jonathan W. Wirtschafter Lecture.

To report the clinical features and differential diagnosis of an unusual entity termed presumed solitary circumscribed retinal astrocytic proliferation (PSCRAP). Retrospective review of medical records. All patients with PSCRAP were asymptomatic, and the lesion was found during routine examination. There were 5 men and 2 women with a median age of 53 years. No patient had a history or clinical findings of tuberous sclerosis complex. Each PSCRAP lesion was circumscribed, abruptly elevated, and opaque white to yellow and mostly obscured the underlying retinal vessels. The lesions had no associated subretinal fluid, hemorrhage, calcification, or retinal traction. Fluorescein angiography disclosed mild hyperfluorescence in the venous phase and moderate late staining of the lesions. Autofluorescence showed mild hyperautofluorescence of the lesions. Ultrasonography revealed no calcification. Optical coherence tomography showed an abruptly elevated retinal mass with optical shadowing posterior to the lesion. Six lesions were stable after a median follow-up of 6 years, and 1 lesion gradually disappeared. The pathogenesis and pathologic features of PSCRAP are unknown. Presumed solitary circumscribed retinal astrocytic proliferation appears to be a unique retinal lesion of adulthood that resembles astrocytic hamartoma or retinoblastoma but displays distinctive ophthalmoscopic features.

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Open Access
The microperimetry of resolved cotton-wool spots in eyes of patients with hypertension and diabetes mellitus.

Retinal cotton-wool spots (CWSs) are an important manifestation of retinovascular disease in hypertension (HTN) and diabetes mellitus (DM). Conventional automated perimetry data have suggested relative scotomas in resolved CWSs; however, this has not been well delineated using microperimetry. This study evaluates the retinal sensitivity in documented resolved CWSs using microperimetry. Retinal CWSs that resolved after 10 to 119 months (median, 51 months) and normal control areas were photographed to document baseline lesions. Eye-tracking, image-stabilized microperimetry with simultaneous scanning laser ophthalmoscopy was performed over resolved CWSs, adjacent uninvolved areas near the lesion, and in location-matched normal patients (age-matched). A total of 16 eyes in patients with DM or HTN (34 resolved CWSs) and 16 normal control eyes (34 areas) were imaged. The mean (SD) sensitivity of resolved CWSs in the eyes of patients with HTN and DM was 11.67 (3.88) dB and 7.21 (5.48) dB, respectively. For adjacent control areas in the eyes of patients with HTN and DM, the mean (SD) sensitivity was 14.00 (2.89) dB and 11.80 (3.45) dB, respectively. Retinal sensitivity was significantly lower in areas of resolved CWSs than in the surrounding controls for patients with HTN (P=.01) and those with DM (P<.001). Scotomas in patients with DM were denser than those of patients with HTN (P<.05). Cotton-wool spots in patients with DM and HTN leave permanent relative scotomas detected by microperimetry. Scotomas are denser in eyes of patients with DM than in those with HTN. In addition, among patients with DM, adjacent retinas not involved with CWSs have lower retinal sensitivity than in age-matched controls.

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Trends in glaucoma medication expenditure: Medical Expenditure Panel Survey 2001-2006.

To study trends of glaucoma medication expenditure from 2001 to 2006 using a nationally representative sample of US adults. We analyzed glaucoma medication expenditure trends among participants of the 2001-2006 Medical Expenditure Panel Survey, a subsample of the National Health Interview Survey, which is a continuous multipurpose, multistage area probability survey of the US civilian noninstitutionalized population. After adjusting for survey design and inflation using the 2009 inflation index, data from 1404 participants 18 years and older using glaucoma medication were analyzed. Mean annual glaucoma medication expenditure per subject increased from $445 in 2001 to $557 in 2006 (slope = 20.8; P < .001). Subgroup analysis showed expenditure increased significantly in women (P = .02), those with public-only insurance (P < .001), and those with less than a high school education (P < .008). Over the survey period, a significant decrease in expenditures on β-blockers (P = .048) and significant increases in expenditures on prostaglandin analogs (P = .01) and α-agonists (P = .01) were found. Factors associated with increasing glaucoma medication expenditure trends include the increasing use of prostaglandin analogs, changes in insurance coverage, and possibly more aggressive glaucoma treatment. The findings are pertinent to the development of cost-effective strategies that optimize treatment and reduce expenditures.

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Open Access
Phenotype associated with mutation in the recently identified autosomal dominant retinitis pigmentosa KLHL7 gene.

To characterize the clinical phenotype, with an emphasis on electrophysiologic findings, in a family with autosomal dominant retinitis pigmentosa caused by mutation in the recently identified KLHL7 gene. Eleven patients from a single family were selected from the Swedish retinitis pigmentosa register. Four patients had been examined 13 to 17 years earlier and underwent further ophthalmologic examination, including visual acuity, fundus inspection, Goldmann perimetry, full-field electroretinography (ERG), multifocal ERG, and optical coherence tomography. KLHL7 mutation was identified by sequence analysis. In most examined family members, the fundus showed minor abnormalities. Full-field ERG demonstrated reduced cone and rod function, but rod responses were preserved in some patients late in life. Follow-up (<or=17 years) demonstrated slowly progressive retinal degeneration. In an adolescent family member, cone and rod function was initially normal, but retinitis pigmentosa was confirmed by electrophysiology 17 years later. Optical coherence tomography and multifocal ERG demonstrated macular abnormalities of varying degree among family members. Genetic analysis revealed a heterozygous exon 6 change (c.458C>T) in 7 family members. Observed in 2 Scandinavian families to date, KLHL7 mutation has recently been associated with autosomal dominant retinitis pigmentosa. Clinical examination with long-term follow-up verified a phenotype with a varying degree of retinal photoreceptor dysfunction and, in some family members, with late onset and preserved rod function until late in life. Clinical Relevance Patients with minor retinal abnormalities and normal ERG findings early in life can harbor an autosomal dominant form of retinitis pigmentosa with a varying degree of visual impediment. Some patients with late onset may retain night vision for many years.

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Open Access
Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004.

To compare US population prevalence estimates for myopia in 1971-1972 and 1999-2004. The 1971-1972 National Health and Nutrition Examination Survey provided the earliest nationally representative estimates for US myopia prevalence; myopia was diagnosed by an algorithm using either lensometry, pinhole visual acuity, and presenting visual acuity (for presenting visual acuity > or =20/40) or retinoscopy (for presenting visual acuity < or =20/50). Using a similar method for diagnosing myopia, we examined data from the 1999-2004 National Health and Nutrition Examination Survey to determine whether myopia prevalence had changed during the 30 years between the 2 surveys. Using the 1971-1972 method, the estimated prevalence of myopia in persons aged 12 to 54 years was significantly higher in 1999-2004 than in 1971-1972 (41.6% vs 25.0%, respectively; P < .001). Prevalence estimates were higher in 1999-2004 than in 1971-1972 for black individuals (33.5% vs 13.0%, respectively; P < .001) and white individuals (43.0% vs 26.3%, respectively; P < .001) and for all levels of myopia severity (>-2.0 diopters [D]: 17.5% vs 13.4%, respectively [P < .001]; < or =-2.0 to >-7.9 D: 22.4% vs 11.4%, respectively [P < .001]; < or =-7.9 D: 1.6% vs 0.2%, respectively [P < .001]). When using similar methods for each period, the prevalence of myopia in the United States appears to be substantially higher in 1999-2004 than 30 years earlier. Identifying modifiable risk factors for myopia could lead to the development of cost-effective interventional strategies.

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Balloon catheter dilation and nasolacrimal duct intubation for treatment of nasolacrimal duct obstruction after failed probing.

To compare the outcomes of balloon catheter dilation and nasolacrimal intubation as treatment for congenital nasolacrimal duct obstruction after failed probing in children younger than 4 years. We conducted a prospective, nonrandomized, multicenter study that enrolled 159 children aged 6 months to younger than 48 months who had a history of a single failed nasolacrimal duct probing and at least 1 of the following clinical signs of nasolacrimal duct obstruction: epiphora, mucous discharge, or increased tear lake. One hundred ninety-nine eyes underwent either balloon catheter nasolacrimal duct dilation or nasolacrimal duct intubation. Treatment success was defined as absence of epiphora, mucous discharge, or increased tear lake at the outcome visit 6 months after surgery. Treatment success was reported in 65 of 84 eyes (77%; 95% confidence interval, 65%-85%) in the balloon catheter dilation group compared with 72 of 88 eyes (84% after adjustment for intereye correlation; 74%-91%) in the nasolacrimal intubation group (risk ratio for success for intubation vs balloon dilation, 1.08; 0.95-1.22). Both balloon catheter dilation and nasolacrimal duct intubation alleviate the clinical signs of persistent nasolacrimal duct obstruction in a similar percentage of patients.

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Open Access