Kazuo Ichikawa

Hereditary Macular Dystrophy without Visible Fundus Abnormality

We found an unusual form of macular dystrophy in three patients from two generations of the same family. The fundi of these patients appeared normal by ophthalmoscopy and fluorescein angiography, even in an older patient and in patients with poor visual acuity. Results of full-field electroretinograms were also normal in both cone and rod components. Focal macular electroretinograms were severely affected, however, indicating retinal impairment in the macular region. Results of Tübingen perimetry were consistent with electroretinographic findings. Since the condition was progressive, this disease is thought to be a hereditary macular dystrophy without visible fundus abnormality.

Two cases of retinal degeneration with an unusual form of electroretinogram

An unusual form of retinal degeneration is reported in 15-year-old girl and 11-year-old girl with different pedigrees, which resembles the cases reported by Gouras and associates (1983). The subjective symptoms in these patients included decreased visual acuity, photophobia, anomalous color vision and night blindness. Electroretinograms (ERGs) in these two patients were identical in substance and revealed drastic alterations in both photopic and scotopic functions. The stimulus versus intensity response curve in a single-flash ERG showed an unusual form. This peculiar supernormal response was elicited by bright stimuli although the stimulus threshold was extremely elevated.

Detection of Acquired Color Vision Defects by Standard Pseudoisochromatic Plates Part 2

We have examined 227 normal subjects, aged from the first to the eighth decade, using SPP 2. We have also examined 100 cases among the outpatients of our clinic, using SPP 2 and the AO-HRR plates. The following results were obtained: (1) the left numeral ‘2’ on the third plate of SPP 2 could not be read by 87.2% of the normal subjects: therefore a misreading of this numeral has no diagnostic value; (2) the other 19 numerals in the SPP 2 were read correctly by 93.8% of the normal subjects: thus one or more abnormal responses for these 19 numerals pointed to acquired color defect; (3) color defects were detected in 20 cases (30.3%) out of 66 cases with some ocular disease which showed corrected visual acuity more than 1.0; (4) SPP 2 might be superior to AO-HRR plates in the detection of color vision defects.

A new lantern test using light-emitting diode lamps

A lantern test using LED lamps has been devised. In this model, two lights each 4 mm in diameter placed 15 mm apart in tandem are presented for 2 seconds at a test distance of 5 m. The color of the light is either red (630 nm), green (555 nm), or yellow (580 nm). All possible combinations of three colors are included in one trial, which consists of nine pairs of lights. The color pairs are presented in random sequence and the number of errors in the second trial is scored. Test results are printed out.

Temporal aspects of the electroretinogram in cone-rod dystrophy.

Twelve patients with cone-rod dystrophy were studied in terms of the temporal aspects of electroretinography (ERG).The peak time of scotopic b-wave was within normal limits in all patients, while the amplitude was reduced in nine patients. The normal peak time of the scotopic-b wave may help explain rod involvement with normal or only slightly elevated final rod thresholds of subjective dark adaptation.The peak time of photopic b-wave and 30-Hz flicker response was normal in four patients and significantly delayed or nonrecordable in eight patients. Such variations of peak time in photopic and 30-Hz flicker ERG may reflect the stage of the disease or may be caused by the different hereditary mode.

Clinical Application of the Transient Tritanopia Effect

Adaptation to long wavelength light leaves the human eye insensitive to short wavelength light. This effect was termed transient tritanopia effect (TTE) by Mollon and Polden (1975). We studied the TTE in patients with several diseases such as open-angle glaucoma, congenital retinoschisis, retinitis pigmentosa and Oguchi’s disease, to verify if the retinal site of the TTE lies in the level of ERG b-wave (Valeton and Norren, 1978). The clinical application of the TTE appears promising for psychophysical localization of retinal lesions.