White Test Light Research Articles

Association of retinal vessel attenuation with visual function in eyes with retinitis pigmentosa.

PurposeTo investigate the association between visual changes and retinal vessel attenuation in patients with retinitis pigmentosa (RP).DesignA retrospective, longitudinal, observational cohort study.MethodsWe analyzed 45 eyes from 45 subjects who were followed-up for ≥3 years at our clinic. Using the computer-based Interactive Vessel Analysis program, central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) were determined. Age- and sex-matched controls from normal subjects were selected from our archived fundus photograph library. Visual acuity, visual field area (Goldmann perimetry, V4e white test light), mean deviation (Humphrey perimetry, central 10-2 program), and central macular thickness (optical coherence tomography) were analyzed for correlations with CRAE and CRVE.ResultsBoth CRAE and CRVE were significantly decreased in RP eyes (94.9±13.5 μm and 155.6±20.0 μm, respectively) compared with control eyes (138.1±14.7 μm and 215.0±20.4 μm, respectively, both P<0.001). After 3 years of follow-up, visual field area was associated with both CRAE (r=0.584, P<0.01) and CRVE (r=0.500, P=0.008). A significant association was also observed between mean deviation and CRAE (r=0.298, P=0.047). In eyes with RP, a narrower vessel caliber at baseline was associated with a larger decline in visual acuity over the 3-year follow-up interval (CRAE: r=−0.344, P=0.021; CRVE: r=−0.314, P=0.035).ConclusionRetinal vessel caliber is associated with some visual functions in patients with RP.

Quantitative Analysis of Retinal Vessel Attenuation in Eyes with Retinitis Pigmentosa

Retinal vessel attenuation is a key finding in the diagnosis of retinitis pigmentosa (RP), but there have been no studies to determine whether quantitative measurement of this retinal sign is useful. We aimed to investigate retinal vessel caliber and its relationship with the severity of RP. This is a cross-sectional study based on 74 patients (145 eyes) with RP who had visual field assessment with Goldmann permeter and good-quality retinal images for vessel size measurements identified by retrospective medial chart review (1973-2007) in the electrophysiology clinic of a tertiary eye hospital in Australia. Retinal vessel calibers were measured using a computer-based program as the central retinal artery and vein equivalent (CRAE and CRVE). Goldmann visual field area for III4e white test light was measured quantitatively using ImageJ software as a clinical parameter to indicate the severity of RP. We used the generalized estimating equation models to estimate the difference in retina vessel calibers accounting for correlation between right and left eyes. Mean CRAE and CRVE were significantly narrower in persons with smaller visual field area. For each 100 cm2 decrease in visual field area, CRAE and CRVE decreased by -15.2 μm (95% confidence interval -20.7, -9.78) and -26.8 μm (-35.1, -18.5), respectively (both P<0.001). In RP patients, the severity of visual field loss is correlated with retinal vessel attenuation. Quantitative retinal vessel caliber measurement may be a useful additional clinical marker for monitoring progression of RP or potential treatment response.

Disease Course of Patients with Unilateral Pigmentary Retinopathy

To evaluate the change in ocular function by eye in patients with unilateral pigmentary retinopathy. Longitudinal regression was used to estimate mean exponential rates of change in Goldmann visual field area (V4e white test light) and in full-field electroretinogram (ERG) amplitudes to 0.5- and 30-Hz white flashes in 15 patients with unilateral pigmentary retinopathy. Snellen visual acuity was assessed case by case. Mean annual rates of change for the affected eyes were -4.9% for visual field area, -4.7% for ERG amplitude to 0.5-Hz flashes, and -4.6% for ERG amplitude to 30-Hz flashes. All three rates were faster than the corresponding age-related rates of change for the fellow normal eyes (P = 0.0006, P = 0.003, P = 0.03, respectively). An initial cone ERG implicit time to 30-Hz flashes in affected eyes ≥ 40 ms predicted a faster mean rate of decline of visual field area and of ERG amplitude to 0.5- and 30-Hz flashes (P < 0.0001 for all three measures). The visual acuity of affected eyes was more likely to decrease in patients presenting at >35 years of age than in patients presenting at a younger age (P = 0.0004). The affected eye in unilateral pigmentary retinopathy shows a progressive loss of peripheral retinal function that cannot be attributed to aging alone and that is faster in eyes with a more prolonged initial cone ERG implicit time. Patients presenting at >35 years of age are at greater risk for losing visual acuity.

Disease Course in Patients with Autosomal Recessive Retinitis Pigmentosa due to theUSH2AGene

To estimate the mean rates of ocular function loss in patients with autosomal recessive retinitis pigmentosa due to USH2A mutations. In 125 patients with USH2A mutations, longitudinal regression was used to estimate mean rates of change in Snellen visual acuity, Goldmann visual field area (V4e white test light), and 30-Hz (cone) full-field electroretinogram amplitude. These rates were compared with those of previously studied cohorts with dominant retinitis pigmentosa due to RHO mutations and with X-linked retinitis pigmentosa due to RPGR mutations. Rates of change in patients with the Cys759Phe mutation, the USH2A mutation associated with nonsyndromic disease, were compared with rates of change in patients with the Glu767fs mutation, the most common USH2A mutation associated with Usher syndrome type II (i.e., retinitis pigmentosa and hearing loss). Mean annual exponential rates of decline for the USH2A patients were 2.6% for visual acuity, 7.0% for visual field area, and 13.2% for electroretinogram amplitude. The rate of acuity loss fell between the corresponding rates for the RHO and RPGR patients, whereas the rates for field and ERG amplitude loss were faster than those for the RHO and RPGR patients. No significant differences were found for patients with the Cys759Phe mutation versus patients with the Glu767fs mutation. On average, USH2A patients lose visual acuity faster than RHO patients and slower than RPGR patients. USH2A patients lose visual field and cone electroretinogram amplitude faster than patients with RHO or RPGR mutations. Patients with a nonsyndromic USH2A mutation have the same retinal disease course as patients with syndromic USH2A disease.

Disease Course of Patients With Pericentral Retinitis Pigmentosa

To estimate the mean rates of decline of ocular function in patients with an atypical form of retinitis pigmentosa, termed "pericentral retinitis pigmentosa." Retrospective observational study. setting: Single-center. patient population: Eighteen patients (ages 32 to 65 years) with pericentral retinitis pigmentosa followed for 3 to 26 years. observational procedures: Snellen visual acuity, Goldmann visual field area (V-4e white test light), and full-field electroretinogram (ERG) amplitudes (0.5 Hz and 30 Hz white flashes). main outcome measures: Mean annual exponential rates of change quantified by repeated-measures longitudinal regression. Estimated mean annual rates of decline of remaining ocular function were 1.2% for visual acuity, 1.9% for visual field area, 2.5% for ERG amplitude to 0.5 Hz flashes, and 2.9% for ERG amplitude to 30 Hz flashes. The mean rates of loss of remaining ocular function of patients with pericentral retinitis pigmentosa were generally slower than those previously reported for patients with typical forms of retinitis pigmentosa.

Ultrastructural Findings in an Autopsy Eye From a Patient With Usher's Syndrome Type II

We studied an eye taken at autopsy from a 55-year-old woman with retinitis pigmentosa and partial deafness (Usher's syndrome type II). Two years before her death, her visual acuity was R.E.: 20/80 and L.E.: 20/50, and visual fields were constricted to a 30- to 40-degree diameter with a V4e white test light. Both rods and cones were present across the retina except for areas of the midperiphery; remaining photoreceptors had shortened or disrupted outer segments, or both, and some cones had inclusion bodies in inner segments. In the macula, most of the connecting cilia of photoreceptors appeared abnormal, with either extra microtubules or an apparent disruption of the nexin link between doublet microtubules. The pigment epithelium was abnormal across the eye, with diminished apical microvilli and basal infoldings of the plasma membrane. Possible mechanisms by which abnormal cilia could lead to photoreceptor cell death are considered.

Phase relations in flicker fusion.

The luminance at which the flicker of a white test light was perceived was determined as a function of the phase angle between the light and pulsing white, green, yellow, red, and blue surround fields which were equated for brightness. It was found that the luminance thresholds for perceived flicker increased when the test light and the surround were in phase. The amount of increase varied as a function of the color of the surround, being a maximum for white, less for green, still less for yellow, and a minimum for red and blue. No differences in absolute threshold were found as a function of phase for 1-sec observation periods of the test flash. The results are discussed with reference to the differences in amplitude as a function of the surround wavelength as well as to submaxima found in the luminance functions.

Retinal Induction in the Light-Adapted Human

Retinal induction of the light-adapted human retina was investigated. 1. When red, green and blue lights are used for preillumination in the light-adapted state of the retina, the peak of the curve of electrical excitability lies at 1, 2 and 3 seconds respectively just as in the dark-adapted retina. As the intensity of the adapting light increases from 0.004 lux to 30 lux, the magnitude of the curve decreases steadily. 2. The curves of retinal induction are not qualitatively different from those obtained from the dark-adapted eye. The retinal induction decays with time in about 5-6 seconds in the retina adapted to a weak general illumination. This is in contrast with the fact that the retinal induction of the dark-adapted retina remains unchanged for about 20 seconds. 3. The magnitude of retinal induction or contrast effect is smaller as the adaptation level of the retina is higher. 4. In the retina light-adapted to a general illumination of 0.004 lux, the white light of 32 lux interposed between the inducing light and the white test light does not affect the direct induction.

Suppression of color contrast and retinal induction by mechanical pressure applied to the eyeball.

The electrical excitability of the dark-adapted eye is increased following an illumination. The effect of a white test light to increase the electrical excitability is remarkably modified when it is preceded by a condition-ing colored light. This modification is measured by the difference between the effect of the white light preceded by colored one and that of the white test light alone. When the conditioning and the test stimuli illuminate successively one and the same retinal area, the effect is called direct induction. It is called indirect induction, when adjacent areas are illumi-nated by the two lights. 1. It was shown that direct induction was little affected when the eye was repeatedly excited by strong white light in the interval between the conditioning and the test lights. 2. Direct or indirect induction was shown to be very sensitive to a mechanical pressure applied to the eyeball. A pressure of 50g. was found to be sufficient to abolish the induction when it was applied to the eye in the interval between the conditioning and the test lights. A pressure of 480g. just stopped the pulsation at the central retinal artery. 3. The depressant effect of a mechanical pressure upon retinal induction outlasted the pressure. Complete recovery occurred in 6, 7 and 10.5 seconds after removal of pressure, 50, 100 and 200g. respectively. 4. Simultaneous color contrast was produced by the method of colored shadows, and its susceptibility to mechanical pressure was investigated. In three of four subjects colored shadows were selectively abolished by a mechanical pressure applied to the eyeball when the intensity of inducing colored light was not too high. 5. The inhibitory effect of mechanical pressure was interpreted as due to anoxia caused by reduction of the rate of blood flow in the retinal capillaries, as was evidenced by entoptic observations of the retinal blood flow.

Retinal induction in various regions of human retina.

By the method of electro-stimulation, retinal induction was measured at various parts of the human retina. 1. The magnitude of retinal induction was found greatest at about 10° from the fovea. This fact might be correlated with the psychological fact that color contrast can most easily be perceived in the para-foveal region of the retina. 2. Red and green lights were found more effective in producing retinal induction than yellow and blue lights. 3. In measurements of retinal induction two photic stimuli are used, i.e., a colored light preceding a white test light. The intensity of retinal induction was shown to be independent of the intensity and the duration of the white test light, but determined by those of the inducing colored light. This law holds good for both foveal and peripheral vision. The authors are indebted to Prof. K. Motokawa for his invaluable advice and encouragement.

Neutralization and propagation of retinal induction in human eye.

The neutralization of retinal induction was quantitatively investigated. 1. The direct induction caused by red filtered light was found to be neutralized by blue-green light from a very narrow range of the spec-trum. The range of the spectrum effective to neutralize the direct in-duction caused by yellow filtered light was found much wider. 2. White light of intensity lower than 5000 lux, which was inter-posed between the inducing colored light and the white test-light did not affect the direct induction caused by the colored light. At higher inten-sities of white light the direct induction was reduced, but this effect could not be identified with the neutralization of retinal induction. 3. It was confirmed that the white light stimulus, even when its intensity was raised to 30, 000lux, had no effect whatsoever upon the excitability curve for the white test-light applied subsequently. 4. It was confirmed that the capacity to produce retinal induction is greatest in a retinal area 15° from the fovea. 5. Some experiments suggesting decremental propagation of spread-ing induction were carried out.