Biomedical subjects

D Neima

Publications and source records attributed to D Neima.

8 recordsLinked to original sources

PubMed1987

Systemic illnesses in cataract patients: 1. Incidence.

To determine the incidence of systemic illnesses in patients presenting for cataract surgery, the hospital charts of 846 consecutive patients who had cataract surgery in 1983 were reviewed. Previously undiagnosed illnesses were found in 35.1% of the patients. The high rate could not be attributed to the fact that a large number of the patients were from rural areas and thus may have had less access to medical care. The incidence rate of diabetes mellitus, 3.5%, appeared higher than would be expected on the basis of recent age-matched population surveys. Recommendations are made for preoperative assessment of cataract patients.

Adult↗

PubMed1987

Systemic illnesses in cataract patients: 2. Prevalence.

In a previous paper we reported an elevated incidence of systemic illnesses in a population of 846 cataract patients. The charts were reviewed to determine the prevalence of systemic illnesses and of drug allergy. Elevated rates of hypertension (46.0%), diabetes mellitus (15.8%), glaucoma (11.0%) and drug allergy (30.6%) were found. Recommendations are made for preoperative assessment of cataract patients.

Adult↗

PubMed1984

Pattern visual evoked potentials and spatial vision in retrobulbar neuritis and multiple sclerosis.

In an attempt to resolve some of the reported disagreements between visual evoked potential (VEP) recordings and Snellen visual acuity in patients with multiple sclerosis, we compared these test results with sine-wave grating-contrast sensitivity curves. Disease that depressed visual sensitivity for high spatial frequencies, sparing low spatial frequencies, was associated with depressed visual acuity and attenuated small-check VEPs in the affected eye, while large-check VEPs were not attenuated. When visual sensitivity to all spatial frequencies was depressed, both large-check and small-check VEPs were attenuated, and Snellen acuity was reduced. In general, abnormalities in the contrast sensitivity curve predicted abnormalities in VEP amplitude, but VEP delay was less accurately predicted.

Adult↗

PubMed1984

Visual field defects in ocular hypertension and glaucoma.

We measured visual fields using three unconventional test stimuli; sine-wave grating targets of 2 and 5 cycles/degree and a visual acuity target. Of 15 patients with ocular hypertension (OHT), eight had visual field defects for contrast sensitivity when tested with a sine-wave grating target of low spatial frequency; these patients had normal perimetric fields and normal fields for visual acuity. We hypothesize that the outer extremities of the largest dendritic trees of retinal ganglion cells become functionally ineffective in some patients with OHT and early glaucoma, possibly due to retinal ischemia, and as a result visual sensitivity to low spatial frequency gratings is reduced while visual acuity is spared. Since this hypothetical mechanism may be somewhat independent of the mechanism that causes ganglion cell loss, not all the contrast field defects in OHT would be expected to progress to glaucomatous field defects and be evident to clinical perimetry.

Aged↗

PubMed1984

Low-contrast letter charts in early diabetic retinopathy, ocular hypertension, glaucoma, and Parkinson's disease.

Diabetes can cause visual loss that is not detected by standard reading tests such as the Snellen test but can be detected by low-contrast letter charts. This visual loss is quite different from loss caused by refractive error. These low-contrast charts are diagnostically at least as sensitive as the sinewave grating contrast sensitivity test. They are inexpensive, and the test is brief and simple. Preliminary evidence is that patients with diabetes who have abnormal low-contrast chart results give abnormal intravenous fluorescein (IVF) test results, even though visual acuity is normal. Low-contrast charts also detect visual loss in patients with ocular hypertension, glaucoma, and Parkinson's disease, including patients with normal visual acuity.

Adult↗

PubMed1984

Balance between pattern and flicker sensitivities in the visual fields of ophthalmological patients.

We measured the balance between visual sensitivities to pattern and to flicker rather than measuring absolute sensitivities to pattern or flicker. The test target was a 2-cycle deg-1 sinewave grating that was counterphase modulated at 8 Hz. Seventeen points in the visual field were tested out to eccentricities of 24 degrees. We examined 10 control subjects, 6 patients with glaucoma 10 with ocular hypertension, and 10 with multiple sclerosis. For controls pattern sensitivity was lower than flicker sensitivity in central vision. The converse held in peripheral vision. The balance between pattern sensitivity and flicker sensitivity was markedly abnormal in part or all of the visual field for many patients. There were examples in all patient groups. In some patients flicker sensitivity was depressed relative to pattern. In others the converse was true. Of 10 patients with ocular hypertension and no perimetric field loss 8 had a significantly abnormal ratio between pattern sensitivity and flicker sensitivity at some point in the visual field. The balance between pattern and flicker sensitivity was more sensitive to visual pathology than absolute sensitivity to either pattern or flicker. We conclude that the relationship between pattern and flicker sensitivity may be more sensitive to visual field damage than is conventional perimetry or visual acuity perimetry.

Adult↗

PubMed1984

Visual fatigue and visual evoked potentials in multiple sclerosis, glaucoma, ocular hypertension and Parkinson's disease.

Visual evoked potential (VEP) abnormality is widely used as an objective indication of visual pathophysiology in the diagnosis of multiple sclerosis. One major limitation of this test is that VEP abnormality is not specific to multiple sclerosis. In an attempt to explore ways of making the VEP test more specific, changes were measured in VEPs caused by superimposing upon the VEP stimulus either a flicker or a moving pattern. The rationale was to test for visual fatigueability, since it is known that some demyelinated axons fatigue rapidly. Of 10 patients with multiple sclerosis, 90% showed VEP fatigue, while none fatigued in the groups of 10 patients with glaucoma and 10 with Parkinson's disease. Fatigue is, however, not completely specific for multiple sclerosis, since three of 10 patients with ocular hypertension showed VEP fatigue.

Adult↗

PubMed1983

Low-contrast letter charts as a test of visual function.

Visual pathway disorders can cause visual loss that is not detected by the Snellen test: visual sensitivity to coarse detail may be depressed, even when visual sensitivity to fine detail is unaffected. Sinewave grating test targets can detect such hidden visual loss. However, electronic apparatus for generating sinewave gratings is expensive, while the inexpensive Arden plates provide no check on the patient's accuracy. We have tested 10 patients and 10 control subjects with a set of five letter charts (including the standard Snellen chart). These letter charts were of different contrasts, namely 10%, 22%, 31%, 64% and 93%, but otherwise were substantially alike. Subjects were also tested with sinewave gratings. We found good agreement between sinewave grating and letter chart findings. In particular, the charts picked up visual loss that was not detected by the standard Snellen chart: they detected visual pathway dysfunction in all seven patients whose sinewave data were abnormal. Our findings suggest that even one low-contrast letter chart could provide a valuable supplement to the standard Snellen chart. Compared with other available devices, these charts have the advantages of cheapness, simplicity and of providing the ophthalmologist with an immediate check on patients' accuracy.

Adult↗