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Biomedical subjects

M A Sandberg

Publications and source records attributed to M A Sandberg.

At least 37 records · Page 2Linked to original sources
PubMed1994

Visual field deficits in early age-related macular degeneration.

Patients with early age-related macular degeneration (AMD) may retain good visual acuity but experience distortion and other qualitative visual changes. The purpose of the present study was to determine whether deficits of form recognition, as well as of light sensitivity, were related to retinal pigment epithelial (RPE) atrophy and/or drusen. We assessed form recognition deficits by the Amsler grid and by a perimetric test of letter recognition and sensitivity deficits by the macular threshold test of the Humphrey Field Analyzer in 59 patients with AMD and visual acuities of 20/40 or better. The number of defects on each test was compared with the area of RPE atrophy and with the area of drusen determined from fundus photographs. Multiple regression analyses based on ordinal data revealed that the number of visual field defects by each test was significantly correlated with the area of atrophy, but not with the area of drusen. There was also no significant tendency for a patient with a regional preponderance of drusen to have more impairment in the corresponding visual field. These results suggest that deficits of form recognition, as well as of sensitivity, in patients with early stages of AMD can be attributed to alteration of photoreceptor function associated with RPE atrophy, but not with drusen.

Aging↗
PubMed1994

Iris pigmentation and extent of disease in patients with neovascular age-related macular degeneration.

PURPOSE: To determine whether the extent of disease in age-related macular degeneration (AMD) varies with iris pigmentation. METHODS: The authors assessed visual function and macular appearance in the fellow eye or both eyes of 132 white patients with unilateral neovascular AMD. All patients had a visual acuity of 20/60 or better in the fellow eye. Eighty-nine of the patients were coded as having light irides (blue, green, or hazel) and 43 were coded as having dark irides (brown); the two groups of patients had comparable mean ages. RESULTS: By the Mann-Whitney test for differences in mean rank, fellow eyes with light irides showed a marginally worse visual acuity (P = .156) but significantly more visual field impairment by letter recognition perimetry (P = .011) and the macular threshold test of the Humphrey Field Analyzer (P = .043), and more retinal pigment epithelial atrophy (P = .017) and focal areas of hyperpigmentation (P = .002) than fellow eyes with dark irides. For eyes with a choroidal neovascular membrane (CNVM), those with light irides had significantly lower visual acuities (P = .006) and larger scars (P = .006) than eyes with dark irides. In addition, extent of disease in the eye with a CNVM was positively correlated with extent of disease in the fellow eye for most comparisons. CONCLUSIONS: These observations suggest that light iris pigmentation is associated with more extensive retinal disease in patients with unilateral neovascular AMD. Furthermore, in such patients, those with worse disease in the eye with a CNVM may tend to have more extensive atrophic disease in the fellow eye.

Aged↗
PubMed1993

A randomized trial of vitamin A and vitamin E supplementation for retinitis pigmentosa.

OBJECTIVE: To determine whether supplements of vitamin A or vitamin E alone or in combination affect the course of retinitis pigmentosa. DESIGN: Randomized, controlled, double-masked trial with 2 x 2 factorial design and duration of 4 to 6 years. Electroretinograms, visual field area, and visual acuity were measured annually. SETTING: Clinical research facility. PATIENTS: 601 patients aged 18 through 49 years with retinitis pigmentosa meeting preset eligibility criteria. Ninety-five percent of the patients completed the study. There were no adverse reactions. INTERVENTION: Patients were assigned to one of four treatment groups receiving 15,000 IU/d of vitamin A, 15,000 IU/d of vitamin A plus 400 IU/d of vitamin E, trace amounts of both vitamins, or 400 IU/d of vitamin E. MAIN OUTCOME MEASURE: Cone electroretinogram amplitude. RESULTS: The two groups receiving 15,000 IU/d of vitamin A had on average a slower rate of decline of retinal function than the two groups not receiving this dosage (P = .01). Among 354 patients with higher initial amplitudes, the two groups receiving 15,000 IU/d of vitamin A were 32% less likely to have a decline in amplitude of 50% or more from baseline in a given year than those not receiving this dosage (P = .01), while the two groups receiving 400 IU/d of vitamin E were 42% more likely to have a decline in amplitude of 50% or more from baseline than those not receiving this dosage (P = .03). While not statistically significant, similar trends were observed for rates of decline of visual field area. Visual acuity declined about 1 letter per year in all groups. CONCLUSIONS: These results support a beneficial effect of 15,000 IU/d of vitamin A and suggest an adverse effect of 400 IU/d of vitamin E on the course of retinitis pigmentosa.

Adolescent↗
PubMed1993

Hyperopia and neovascularization in age-related macular degeneration.

PURPOSE: Refractive errors for phakic eyes of patients referred with age-related macular degeneration were reviewed to determine whether some range of refractive error might be a risk factor for the neovascular form. METHODS: The authors compared refractive errors of 198 patients with unilateral neovascular disease with refractive errors of 129 patients with bilateral dry disease. These groups had comparable distributions with respect to age, sex, and visual acuity of their better eyes. Student's t tests and multiple linear regression analyses were performed to assess group differences in mean refractive error. Contingency table and multiple logistic regression analyses were performed to determine odds ratios for having the neovascular form based on a stratification of refractive error. RESULTS: By comparing better eyes of the two groups, patients with the unilateral neovascular form had an average spherical equivalent that was 1.0 diopter (D) more hyperopic than that of patients with the bilateral dry form (P < 0.001). Patients with a refractive error of +0.75 D or greater were more likely to have the neovascular form compared with patients with other refractive errors (odds ratio, 2.40; 95% confidence interval, 1.53-3.78; P < 0.001). Similar relationships between the two groups of patients were found by comparing worse eyes. CONCLUSION: These findings suggest that hyperopia is a risk factor for choroidal neovascularization among patients referred with age-related macular degeneration.

Aged↗
PubMed1993

A null mutation in the human peripherin/RDS gene in a family with autosomal dominant retinitis punctata albescens.

The murine rds (retinal degeneration slow) allele is a semidominant null allele that causes photoreceptor degeneration. The wild-type sequence at the rds locus encodes a photoreceptor disc membrane protein named peripherin/RDS. Mutations in the homologous human peripherin/RDS gene can cause autosomal dominant retinitis pigmentosa, but these are missense mutations or deletions of single codons. No obvious null alleles have been reported in humans, so that the human phenotype corresponding to rds is as yet unknown. Here we report a 2-basepair deletion in codon 25 of the human gene in a family with autosomal dominant retinitis punctata albescens, suggesting that this disease, rather than retinitis pigmentosa, is the comparable human phenotype.

Alleles↗
PubMed1993

Recessive mutations in the gene encoding the beta-subunit of rod phosphodiesterase in patients with retinitis pigmentosa.

We have found four mutations in the human gene encoding the beta-subunit of rod cGMP phosphodiesterase (PDE beta) that cosegregate with autosomal recessive retinitis pigmentosa, a degenerative disease of photoreceptors. In one family two affected siblings both carry allelic nonsense mutations at codons 298 and 531. Affected individuals have abnormal rod and cone electroretinograms. PDE beta is the second member of the phototransduction cascade besides rhodopsin that is absent or altered as a cause of retinitis pigmentosa, suggesting that other members of this pathway may be defective in other forms of this disease.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

Foveal cone ERGs in fellow eyes of patients with unilateral neovascular age-related macular degeneration.

PURPOSE: To determine whether fellow eyes with normal visual acuity of patients with unilateral neovascular age-related macular degeneration (AMD) have retinal malfunction. METHODS: Foveal cone electroretinograms (ERGs) were recorded from fellow eyes with visual acuities of 20/25 or better of 73 patients with unilateral neovascular AMD and from 28 normal volunteers of comparable age. Responses were elicited with a 4 degrees stimulus flickering at 42 Hz presented by a stimulator-ophthalmoscope. RESULTS: The study eyes of the patients were found to have foveal cone ERGs that, on average, were normal in amplitude but delayed in implicit (peak) time after adjustment of the data for age, sex, iris pigmentation, and refractive error by multiple linear regression. Based on all subjects, amplitude declined with increasing age and was smaller in eyes with darker irides; implicit time increased with increasing age. CONCLUSIONS: These findings suggest that fellow eyes with normal visual acuity of patients with unilateral neovascular AMD tend to have foveal cones that are normal in number but that function abnormally. In addition, foveal cone ERG amplitude should be adjusted for both age and iris pigmentation and implicit time should be adjusted for age when assessing retinal function of elderly patients.

Aged↗
PubMed1992

Retinocalcarine function in Alzheimer's disease. A clinical and electrophysiological study.

Impaired visual function in Alzheimer's disease (AD) could result from either precortical or cortical lesions, or both. In a parallel psychophysical study of visual function in AD, we found that contrast sensitivity function, color vision, stereoacuity, and backward masking were impaired relative to the performance of age-matched control subjects, whereas performance on a critical flicker fusion test was normal. The intent of the present study was to determine whether abnormalities of the retinocalcarine pathway contribute to visual dysfunction. We performed neuro-ophthalmological examinations on 38 patients with AD; from this group, 25 received additional psychophysical testing and 13 underwent electrophysiological testing. Clinical neuro-ophthalmological examinations, full-field electroretinograms, focal electroretinograms, and pattern visual evoked potentials were normal in all patients tested. There was no evidence of retinocalcarine abnormality specific to AD. We conclude that the visual impairment experienced by some patients with AD primarily results from involvement of the visual association cortices rather than from precortical damage, at least before the end stage of the disease.

Aged↗
PubMed1992

Foveal cone electroretinograms in patients with central visual loss of unexplained etiology.

Foveal cone electroretinograms (ERGs) were recorded in five patients (aged 24 to 66 years) referred because of central visual loss of unexplained etiology. These patients had no family history of visual loss and no diagnostic fundus abnormalities seen on ophthalmoscopy or fluorescein angiography. Foveal cone ERGs were elicited with a 4 degrees white stimulus flickering at 42 Hz centered within a steady 10 degrees white surround presented through the dilated pupil to the fovea by a hand-held, dual-beam stimulator-ophthalmoscope. All five patients showed reduced foveal cone ERG amplitudes. Their abnormal responses were similar to those previously reported in cases of clinically apparent macular degeneration and contrasted with previously reported normal responses in patients with optic atrophy or strabismic amblyopia. The progressive loss of central vision as determined by history and these subnormal foveal cone ERG amplitudes suggest that these patients have a form of macular degeneration.

Adult↗
PubMed1992

A null mutation in the rhodopsin gene causes rod photoreceptor dysfunction and autosomal recessive retinitis pigmentosa.

Mutations within the rhodopsin gene are known to give rise to autosomal dominant retinitis pigmentosa (RP), a common hereditary form of retinal degeneration. We now describe a patient with autosomal recessive RP who is homozygous for a nonsense mutation at codon 249 within exon 4 of the rhodopsin gene. This null mutation, the first gene defect identified in autosomal recessive retinitis pigmentosa, should result in a functionally inactive rhodopsin protein that is missing the sixth and seventh transmembrane domains including the 11-cis-retinal attachment site. We also found a different null mutation carried heterozygously by an unrelated unaffected individual. Heterozygous carriers of either mutation had normal ophthalmologic examinations but their electroretinograms revealed an abnormality in rod photoreceptor function.

Adaptation, Ocular↗
PubMed1991

Hydroxychloroquine retinopathy.

We analyzed ocular findings from two patients (aged 49 and 60 years) with hydroxychloroquine (Plaquenil, Winthrop Pharmaceuticals, Division of Sterling Drug, Inc., New York, New York) retinopathy. Both patients were treated for systemic lupus erythematosus; one patient was treated with 400 to 800 mg of hydroxychloroquine per day (6.1 to 12.2 mg/kg of body weight/day) over a ten-year period. Cumulative doses were 1,788 and 2,920 g, respectively. Neither patient had ever been treated with chloroquine. One patient complained of glare and difficulty in adjusting to changes in illumination, whereas the other was asymptomatic. Both had bilateral visual acuities of 20/25, pericentral scotomata, and increased final dark-adapted rod thresholds in the two retinal areas that were tested. Fullfield electroretinograms were reduced and delayed, and focal cone electroretinography showed abnormal foveal responses as well. Ophthalmoscopy and fluorescein angiography showed a bull's-eye maculopathy in both eyes of one patient and perifoveal depigmentation in both eyes of the other patient. Retinal function remained stable at follow-up examinations 18 to 24 months after the cessation of hydroxychloroquine treatment. These two cases demonstrate that peripheral retinopathy, as well as maculopathy, can develop in patients who are treated with hydroxychloroquine for systemic lupus erythematosus, and that retinal function may remain stable after discontinuation of hydroxychloroquine treatment.

Electroretinography↗
PubMed1991

Ocular findings in patients with autosomal dominant retinitis pigmentosa and rhodopsin, proline-347-leucine.

We studied the ocular findings in eight unrelated patients with a form of autosomal dominant retinitis pigmentosa and the same cytosine-to-thymine transition in the second nucleotide of codon 347 of the rhodopsin gene. This mutation, detected in leukocyte DNA, corresponds to a substitution of leucine for proline in amino acid 347 of the rhodopsin protein, and, therefore, we designated this form of retinitis pigmentosa as rhodopsin, proline-347-leucine. On average, these patients had significantly smaller visual field areas and smaller electroretinogram amplitudes than 140 unrelated patients of comparable age with dominant retinitis pigmentosa without this mutation. The findings in eight relatives with this mutation from three of these families are presented to provide examples of the variability that exists in the clinical severity of this disease.

Adolescent↗
PubMed1991

Ocular findings in patients with autosomal dominant retinitis pigmentosa and a rhodopsin gene defect (Pro-23-His).

Ocular findings are presented from 17 unrelated patients with a form of autosomal dominant retinitis pigmentosa and the same cytosine-to-adenine transversion in codon 23 of the rhodopsin gene corresponding to a substitution of histidine for proline in the 23rd amino acid of rhodopsin (designated rhodopsin, Pro-23-His). On average, these patients (mean age, 37 years) had significantly better visual acuity and larger electroretinographic amplitudes than 131 unrelated patients (mean age, 32 years) with autosomal dominant retinitis pigmentosa without this mutation. However, these 17 patients from separate families, as well as 12 relatives with the mutation from four of these families, showed interfamilial and intrafamilial variability with respect to severity of their ocular disease, suggesting that some factor(s) other than this gene defect itself is involved in the expression of their condition. This form of retinitis pigmentosa can now be detected by testing leukocyte DNA from peripheral blood. Some mechanisms by which this mutation in the rhodopsin gene could lead to rod photoreceptor cell death are suggested.

Adolescent↗
PubMed1991

Effects of IBMX on the rod ERG of the isolated perfused cat eye: antagonism with light, calcium or L-cis-diltiazem.

Full-field electroretinograms (ERGs) were recorded from isolated cat eyes perfused through the ophthalmociliary artery with the cGMP-PDE inhibitor, 3-isobutylmethylxanthine (IBMX). Under dark-adapted conditions perfusion with IBMX resulted in reduced ERG b-wave amplitudes at low stimulus luminances and supernormal b-wave amplitudes at high stimulus luminances with reduced b-wave sensitivity; b-wave implicit times were more delayed at low than at high stimulus luminances. Presentation of a steady white background or high calcium fully reversed the supernormal amplitudes and partially reversed the delayed implicit times produced by IBMX. Rod ERG b-wave sensitivity, reduced with IBMX alone, was partially reversed with calcium but further reduced with background light. Perfusion with the cation channel blocker, L-cis-diltiazem, also reversed the supernormal amplitudes produced by IBMX but had no effect on implicit times or b-wave sensitivity. Possible mechanisms of action of these antagonists and clinical implications of these findings are considered.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Autosomal dominant retinitis pigmentosa with rhodopsin, valine-345-methionine.

Rhodopsin gene mutations appear to cause some forms of autosomal dominant retinitis pigmentosa. In the family described, the mutation called rhodopsin, Val345Met segregated perfectly with the disease. All affected individuals had abnormal ERGs; the two oldest members of this family had more loss of function than the two youngest members. Some intra-familial variability existed as an older member showed larger visual fields and ERG amplitudes than a younger member. This mutation was not seen in 106 control subjects nor in any other patients yet described with other rhodopsin gene mutations. Patients so far studied with rhodopsin, Val345Met, have smaller 0.5-Hz full-field ERG amplitudes, on average, than those with Pro23His or Thr58Arg and larger ERG amplitudes than those with Pro347Leu or Pro347Ser. These forms of retinitis pigmentosa can now be detected through analysis of leukocyte DNA.

Adult↗
PubMed1991

Cone electroretinographic change during light adaptation in retinitis pigmentosa.

Cone electroretinograms (ERGs) to 30-Hz full-field white light were recorded after dark adaptation from 33 patients with retinitis pigmentosa and 8 normal subjects over a period averaging 8.5 min. Most patients and all normal subjects showed increases in amplitude that approached or reached maximum by the end of the recording. Regression analyses revealed that patients with smaller baseline amplitudes tended to show larger and faster increases in relative amplitude than patients with larger baseline amplitudes, whose amplitude changes over time were comparable to those seen in normal subjects. These findings suggest that both the magnitude and kinetics of cone ERG amplitude change to a light-adapting, flickering stimulus are related directly to the level of cone malfunction in retinitis pigmentosa.

Adaptation, Physiological↗
PubMed1991

Normal change in the foveal cone ERG with increasing duration of light exposure.

Foveal cone electroretinograms (ERG) were elicited with a stimulator-ophthalmoscope from 24 normal subjects with a 4 degrees stimulus flickering at 42 Hz and centered within a 12 degrees steady surround. The stimulus and surround were presented at retinal illuminances of 4.8 log td and 5.5 log td, respectively, to facilitate visualization of the fundus. Several consecutive averaged responses were evaluated to determine whether increasing duration of light exposure causes an increase in amplitude, as previously found for the full-field cone ERG. On average, amplitude increased by 27% over time, and the linear regression of amplitude on recording number accounted, on average, for 42% of the amplitude variability between consecutive responses. Two subjects had amplitudes that were initially subnormal, based on previously published norms, but that value increased to within the normal range in subsequent recordings. These findings show that a significant change in the cone ERG occurs in the fovea with increasing duration of light exposure at these retinal illuminances, and suggest that, when the stimulator-ophthalmoscope is used, consecutive foveal cone ERGs should be obtained from patients with suspected macular disease to avoid a false diagnosis of retinal malfunction.

Adolescent↗