The Stiles-Crawford effect in retinitis pigmentosa.

Stiles-Crawford functions were obtained from the maculas of 22 patients with different genetic types of retinitis pigmentosa and visual acuity of 20/40 or better. Reduced cone directional sensitivity was seen in the fovea with both focal cone electroretinographic testing and psychophysical testing. Functions from the parafovea determined with psychophysical testing showed either significant flattening or displaced peak locations.

A two year trial of low protein, low arginine diets or vitamin B6 for patients with gyrate atrophy.

Four patients with gyrate atrophy on low protein (20-35 g/day), low arginine diets and one on vitamin B6 (300 mgm/day) have maintained their plasma ornithine concentrations in the range of 30-60% of pre-therapeutic trial levels for about two years. After two years, three of the five patients have shown no significant change in Snellen visual acuity, visual fields, final dark-adapted thresholds or full-field electroretinograms. All five patients have shown slight enlargement of areas of chorioretinal atrophy in the midperiphery.

Temporal aspects of the dark-adapted cone a-wave in retinitis pigmentosa.

Cone electroretinograms were elicited with a full-field red flash after-45 min of dark adaptation from 16 patients with retinitis pigmentosa and from 17 normal subjects. The average latency and implicit time of the cone a-waves recorded from the patients were each significantly delayed (p less than 0.005) compared with the average normal values.

Retinal degeneration in cats fed casein. IV. The early receptor potential.

Electroretinographic studies of casein-fed cats with retinal taurine deficiency revealed that the early receptor potential (ERP) was initially normal in amplitude at a time when the a-wave and b-wave of the electroretinogram were substantially reduced or even nondetectable. The preserved ERP's in these taurine-deficient cats could be correlated with the histologic finding that their outer segments were relatively intact over 90% of the retinal area subtended by the test flash. The sequence of electroretinographic changes in these taurine-deficient cats was also consistent with previous biochemical studies on the normal cat retina that have shown a relatively low concentration of taurine at the level of the outer segments and a higher concentration at the level of the inner segments.

Retinitis pigmentosa and allied diseases: applications of electroretinographic testing.

Electroretinograms (ERGs) have provided criteria for establishing the diagnosis of retinitis pigmentosa in early life even at a time when fundus abnormalities visible with the ophthalmoscope are minimal or absent. Patients with widespread progressive forms of retinitis pigmentosa have shown not only reduced amplitudes but also delays in cone or rod b-wave implicit times, or both, while patients with self-limited sector retinitis pigmentosa or stationary forms of night blindness have had reduced amplitudes with normal b-wave implicit times. In families with retinitis pigmentosa ERGs can be used not only to identify which patients are affected but also to establish which patients are normal as those patients, age 6 and over, with normal cone and rod amplitudes and normal cone and rod b-wave implicit times have not been observed to develop primary retinitis pigmentosa at a later time.

Reduction of hyperornithinemia with a low protein, low arginine diet and pyridoxine in patients with a deficiency of ornithine-ketoacid transaminase (OKT) activity and gyrate atrophy of the choroid and retina.

Five patients with gyrate atrophy of the choroid and retina showed a 60% of greater decline in plasma ornithine levels during a five week trial of a low protein (10--15 g/day), low arginine (0.50--0.75 g/day) diet supplemented with essential amino acids and pyridoxine administration.

Rod-cone interaction in the distal human retina.

During the rod-isolated phase of dark adaption, b-wave implicit time of the human cone electroretinogram increased exponentially with a time constant corresponding to that for the regeneration of rhodopsin. In the presence of different photopically equated short-wave backgrounds, cone b-wave implicit time varied inversely with the scotopic brightness of the background. Taking into account the origin of the b wave, these measurements support the idea of a rod effect on cone function in the distal human retina.

Ocular findings in patients with gyrate atrophy on pyridoxine and low-protein, low-arginine diets.

Five patients, ages 12 to 30, with gyrate atrophy have shown substantial (60% or greater) decreases in plasma ornithine concentrations within four to eight weeks when placed on a therapeutic trial of low-protein (10-15 g/day), low-arginine diets supplemented with essential amino acids (EAA) and pyridoxine hydrochloride. Four of five patients have continued on modified protein restriction (20-35 g/day) and one on pyridoxine (300 mg/day) alone with maintenance of plasma ornithine in the range of 30 to 60% below pretherapeutic trial levels. After one year, four of five patients have shown no significant improvement in visual acuity, fields, final dark-adapted thresholds, electroretinograms, or fundus appearance.

Postmortem metabolic capacity of photoreceptor cells in human and rat retinas.

Retinas of postmortem human donor eyes retained the high-affinity mechanism for uptake of 3H-taurine, the capacity to synthesize rhodopsin from 14C-amino acids, and the ability to incorporate inorganic 32P-phosphate into rhodopsin with exposure to light for 4 to 4 1/2 hr. These processes declined at a rate of about 16% to 19% per hour between 2 and 4 1/2 hr after death. Parallel studies with rats maintained after death at room temperature (22 degrees C) showed that all three processes declined linearly at rates of 8% to 12% per hour.

Risk factors for genetic typing and detection in retinitis pigmentosa.

An outpatient population with retinitis pigmentosa was evaluated with respect to best corrected visual acuity, cycloplegic refractive error, appearance of the lenses, presence or absence of bone spicule pigmentation, age of onset of night blindness by history, and presence or absence of a history of parental consanguinity. The population included 489 affected patients subdivided into the four following groups: 69 (14.1%) dominant, 67 (13.

Electroretinograms in English setters with neuronal ceroid lipofuscinosis.

Full-field electroretinograms (ERGs) were recorded from three adult English setters with advanced neuronal ceroid lipofuscinosis and three normal controls. Affected setters showed 30% to 40% reductions in a-wave and b-wave amplitudes, normal cone and rod b-wave implicit times, and slightly elevated a-wave and b-wave thresholds. The ERGs of these affected setters differed from those that have been recorded from humans with neuromal ceroid lipofuscinosis (Batten's disease), humans with hereditary retinitis pigmentosa, Irish setters with rod-cone dysplasia, and miniature French poodles with progressive rod-cone degeneration.

Foveal cone electroretinograms in retinitis pigmentosa and juvenile maular degeneration.

Foveal cone electroretinograms were elicited with a hand-held stimulator-ophthalmoscope from 16 patients with retinitis pigmentosa and 17 patients with juvenile macular degeneration. Among 11 patients with retinitis pigmentosa and visual acuities of 6/9 (20/30) or better, eight had foveal cone ERGs that were normal in amplitude and b-wave implicit time; all five patients tested with visual acuities of 6/12 (20/40) to 6/18 (20/60) had foveal cone ERGs that were reduced in amplitude and normal in implicit time. All patients with juvenile macular degeneration and visual acuities of 6/15 (20/50) or worse showed subnormal amplitudes with normal or delayed implicit times, or responses indistinguishable from noise.

Dominant retinitis pigmentosa with reduced penetrance. Further studies of the electroretinogram.

Full-field electroretinograms (ERGs) were recorded after a ten-year interval from four affected patients in a family with dominant retinitis pigmentosa with reduced penetrance; all patients showed decreases in amplitude. Cone ERGs from affected patients (aged 11 to 15 years) in this family as well as from affected patients of comparable ages from two other families with this genetic type, were normal or slightly reduced in amplitude and substantially delayed in b-wave implicit time. In one family, an asymptomatic older patient, representing an apparent skipped generation, showed abnormal full-field cone and rod ERGs that differed in implicit times from those of young affected patients.

Electroretinographic testing as an aid in detection of carriers of X-chromosome-linked retinitis pigmentosa.

Twenty-two of 23 obligate female carriers in nine families with known X-chromosome-linked retinitis pigmentosa were detected on the basis of abnormal full-field electroretinograms (ERGs). Only 14 of these carriers had fundus findings characteristic of the carrier state. Electroretinograms of carriers were either reduced in amplitude to white light under dark-adapted conditions or delayed in cone b-wave implicit time, or both.

Sex-linked retinitis pigmentosa: ultrastructure of photoreceptors and pigment epithelium.

An ultrastructural study of a postmortem donor eye from a 24-year-old male patient with sex-linked retinitis pigmentosa showed abnormalities in all remaining cones and rods. Central foveal cones were reduced in number by about 50% and had shortened and severely distorted outer segments. Cones from the parafovea through the midperiphery gradually decreased in density and had no organized outer segments.

Foveal cone electroretinograms in strabismic amblyopia: comparison with juvenile macular degeneration, macular scars, and optic atrophy.

A hand-held stimulator-ophthalmoscope was used to elicit foveal cone electroretinograms (ERGs) from fifteen patients with strabismic amblyopia. The ERGs were in response to a 4 degrees stimulus visualized on the fundus and centred on the fovea throughout testing. Foveal cone ERGs from amblyopic eyes were normal in amplitude and normal in b-wave implicit time.

Ocular and biochemical abnormalities in gyrate atrophy of the choroid and retina.

Patients with gyrate atrophy of the choroid and retina have myopia, constricted visual fields, elevated dark adaptation thresholds, small or nondetectable ERGs, and chorioretinal atrophy. Biochemical abnormalities include hyperornithinemia, hypolysinemia, hyperornithinuria, an unknown amino compound in the urine, and virtual absence of OKT activity in extracts of cultured skin fibroblasts. Extracts of cultured skin fibroblasts from one patient studied in our laboratory showed an increase in OKT activity with increasing concentrations of vitamin B6 in the assay medium; this patient also showed some biochemical responsiveness within three weeks to 300 mg/day or orally administered vitamin B6.

Ornithine ketoacid transaminase deficiency in gyrate atrophy of the choroid and retina.

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration associated with hyperornithinemia with an autosomal recessive mode of inheritance. Cultured skin fibroblasts from five affected patients showed a virtual absence of ornithine ketoacid transaminase (OKT) (L-ornithine:2-oxoacid aminotransferase E.C.

Visually evoked response testing with a stimulator-ophthalmoscope. Macular scars, hereditary macular degenerations, and retinitis pigmentosa.

Visually evoked responses (VERs) were recorded from 47 patients under age 60 years with macular scars, hereditary macular degenerations, or retinitis pigmentosa. A hand-held, two-channel stimulator-ophthalmoscope was used to present to the central fovea a 1.5 degrees flickering stimulus centrally superimposed on a steady 10 degrees background.

Retinal ultrastructure in advanced retinitis pigmentosa.

An ultrastructural study of the retina of a patient with advanced retinitis pigmentosa revealed an orderly process of cone degeneration with more advanced stages in the perifovea and less advanced stages in the fovea. No rod photoreceptors were seen. Remaining cones had enlarged nuclei with autophagic vacuoles and bundles of parallel undulating 12 nm.