Francisco M. de Monasterio

Age and illuminance effects in the Farnsworth-Munsell 100-hue test

Seventy-five normal volunteers (20-78 yr) were tested on the Farnsworth-Munsell 100-hue test at each of five illuminance levels. Each cap score distribution was analyzed by fitting a two-cycle sine wave whose amplitude and phase characterize the polarity of the error distribution and its axis. Analysis of these parameters reveals a similarity between tritanlike defects in older groups and those of younger groups at lower illuminance levels. These data are also useful for specifying age norms for the polarity of the error distribution.

Safety And Pharmacokinetics Of A Preservative-free Triamcinolone Acetonide Formulation For Intravitreal Administration

Purpose: The safety and pharmacokinetics of a triamcinolone acetonide (TA) preservative-free (TA-PF) formulation were investigated after intravitreal administration in rabbits. Methods: A TA-PF formulation was prepared as a sterile 40-mg/mL or 160-mg/mL suspension in single-use vials by adding TA powder to 0.5% hydroxypropyl methylcellulose in normal saline. TA-PF (4-mg and 16-mg doses) and Kenalog (Bristol-Myers-Squibb, Princeton, NJ) (4-mg dose) were injected into the vitreous of separate groups of rabbits, and drug levels were measured in the vitreous over time with HPLC. Ocular toxicology (clinical examination, serial electroretinography, and histopathologic analysis) was evaluated in a separate group of animals after intravitreal TA-PF injection. Results: The half-lives of the injection amount in the vitreous, 4-mg TA-PF, 16-mg TA-PF, and 4-mg Kenalog, were found to be 24 days, 39 days, and 23 days, respectively. There were no signs of toxicities by clinical examination after TA-PF injection. Serial electroretinograms of rabbits receiving either 4-mg or 16-mg intravitreal TA-PF injections remained normal over time. Histopathologic analysis showed normal ocular tissues in animals receiving either 4-mg or 16-mg intravitreal TA-PF injections. Conclusion: The half-life of TA in the vitreous after a 4-mg injection of either TA-PF or Kenalog was comparable. A 16-mg dose of TA-PF produced a long vitreous half-life, and this may be of clinical benefit in patients requiring 6 months of drug exposure in the eye for a chronic disease.

Oral Supplementation of Lutein/Zeaxanthin and Omega-3 Long Chain Polyunsaturated Fatty Acids in Persons Aged 60 Years or Older, with or without AMD

PURPOSE Increased dietary intake of lutein/zeaxanthin and omega-long-chain polyunsaturated fatty acids (omega-3 LCPUFA) was found to be associated with reduced risk of advanced age-related macular degeneration (AMD). The purpose of the study was to examine the effect of oral supplementation of omega-3 LCPUFA on changes in serum levels of lutein/zeaxanthin during supplementation in persons 60 years of age and older, with or without AMD. METHODS Forty participants with AMD of various degrees of severity received lutein (10 mg) and zeaxanthin (2 mg) daily and were equally randomized to receive omega-3 LCPUFA (350 mg docosahexaenoic acid [DHA] and 650 mg eicosapentaenoic acid [EPA]) or placebo for 6 months. Serum levels of lutein, zeaxanthin, and omega-3 LCPUFAs and macular pigment optical densities were measured at baseline, 1 week, and 1, 3, 6, and 9 months. RESULTS By month 6, the median serum levels of lutein/zeaxanthin increased by two- to threefold compared with baseline. Increases in serum levels of lutein/zeaxanthin did not differ by omega-3 LCPUFA treatment (P > 0.5). After 1 month, in the omega-3 LCPUFA-treated group, the median levels of DHA and EPA increased and the placebo group had no changes. At month 6, participants with AMD had a lower increase in serum lutein concentration than did those without AMD (P < 0.05). CONCLUSIONS The addition of omega-3 LCPUFA to oral supplementation of lutein/zeaxanthin did not change the serum levels of lutein and zeaxanthin. A long-term large clinical trial is necessary to investigate the benefits and adverse effects of these factors for the treatment of AMD.

Gyrate Atrophy of the Choroid and Retina: Early Findings

Examination of two sisters ages 2 years 10 months and 6 years four months with gyrate atrophy of the choroid and retina provided an opportunity for detailed clinical investigation. Although the chorioretinal lesions were confined to the peripheral retina in the older case and were quite minimal in the younger case, there was electroretinographic evidence of marked involvement of the cone and rod systems. These cases offer an opportunity to assess an arginine restricted diet in preventing the progress of the disease.

FUNCTIONAL PROPERTIES AND PRESUMED ROLES OF RETINAL GANGLION CELLS OF THE MONKEY

Publisher Summary This chapter discusses the functional properties and presumed roles of retinal ganglion cells of the monkey. For purposes of generalizations, ganglion cell types can be organized into various groups: (1) spectrally-opponent neurons, (2) spectrally non-opponent neurons, and (3) atypically-organized neurons. Nearly 25% of the neurons of the spectrally-opponent neurons group show a concealment of their wavelength-dependent responses because of remarkably weak surround antagonism. Unless the center sensitivity is selectively depressed, the responses of spectrally-opponent neurons mimic those of spectrally non-opponent cells and show neither spectral nor spatial opponency. The classifications of cell types often have implicit or explicit underlying assumptions about the functional role that the various cell types may have. This is particularly common in the non-human primate studies of sensory physiology. It is a common assumption that spectrally-opponent cells play an important part in color vision, that is, ones ability to discriminate between stimuli differing in wavelength but not in luminance.

Gyrate atrophy of the choroid and retina

Ornithine-delta-aminotransferase deficiency is the primary biochemical defect in gyrate atrophy of the choroid and retina and results in the characteristic accumulation of ornithine. An additional consequence of this inborn error is that arginine, the precursor of ornithine, becomes an essential amino acid. Therefore, to reduce the accumulated ornithine, we placed nine gyrate atrophy patients on an arginine-restricted diet. Plasma ornithine decreased by 50 to 85% within one month. Orally administered, alpha-aminoisobutyric acid facilitated the reduction in ornithine by augmenting renal losses. Over the long term, three patients have maintained near normal plasma ornithine concentrations from 4 to 32 months. Two patients have maintained less striking reductions in ornithine, and four have either been poorly controlled or have terminated the diet. Urinary losses of arginine and ornithine in gyrate atrophy patients with high or low plasma ornithine concentrations are less than 50% of the estimated arginine intake. This observation suggests that the bulk of ingested arginine is somehow metabolized despite the severe reduction in ornithine-delta-aminotransferase activity.Gyrate atrophy of the choroid and retina, which is often shortened to gyrate atrophy, is an inherited disorder characterized by progressive vision loss. People with this disorder have an ongoing loss of cells (atrophy) in the retina, which is the specialized lightsensitive tissue that lines the back of the eye, and in a nearby tissue layer called the choroid. During childhood, they begin experiencing nearsightedness (myopia), difficulty seeing in low light (night blindness), and loss of side (peripheral) vision. Over time, their field of vision continues to narrow, resulting in tunnel vision. Many people with gyrate atrophy also develop clouding of the lens of the eyes (cataracts). These progressive vision changes lead to blindness by about the age of 50.

Clinical measurement of saturation discrimination.

In this paper, we describe how a circular reflective neutral-density wedge can be used to construct an apparatus which provides a relatively rapid procedure for the clinical measurement of saturation discrimination. Subsequent to an initial measurement of the patients relative luminosity function, the patient need only turn a single control which varies the colorimetric purity of a test field which remains luminance matched to a white light reference field.

Saturation Discrimination and the Degree of Diabetic Retinopathy

A blue-yellow deficiency is generally observed when color vision is altered secondary to diabetes. What is not clear, however, is the relationship between the degree of retinopathy and the degree of color deficiency. We have measured spectral saturation discrimination (from 430–680 nm) in normal and diabetic subjects as the first perceptible step from a white reference field (x = 0.45, y = 0.43). We used an optical system which permitted the patient to vary colorimetric purity (at constant luminance) by adjusting a single control knob. Constancy of luminance was assured by preliminary measurement of each patient’s relative luminosity function. All diabetic subjects had normal visual acuity. Diabetic patients without retinopathy showed normal saturation discrimination functions. However, in patients with retinopathy, there was little correlation between losses in saturation discrimination and the degree of retinopathy. That is, a patient having minimal retinopathy, can manifest the same loss in saturation discrimination as a patient having severe background retinopathy.

Quantitative Comparison of Farnsworth and Kinnear Plots of the Farnsworth-Munsell 100-Hue Test

The cap scores of the Farnsworth-Munsell 100-hue tests from 75 normal observers were plotted according to Farnsworth and Kinnear methods. The polarities and axes of the distributions resulting from the two methods were compared using two different algorithms for estimating polarity and one for estimating axis orientation. Both methods of plotting the cap scores yielded estimates of polarity and axis orientation that did not differ significantly for any of the algorithms tested.