Donald A. Grover

Coloration of human lenses by near ultraviolet photo-oxidized tryptophan ☆

Abstract When human lenses in vitro and solutions of extracted crystallins were irradiated for 48 hr with near u.v. light in the presence of tryptophan their absorption of visible light (at 440 nm) increased and they became more intensely yellow-brown. As a result the absorption of u.v. light and the blue visible fluorescence of all lens crystallin fractions increased at least several fold. The observations suggest a role of environmental near u.v. light in the intensification of human lens color with aging. Both beneficial and harmful effects may result from such lens color darkening.

The influences of age, retinal topography, and gender on retinal degeneration in the Fischer 344 rat

The Fischer 344 (F344) rat is presently the animal of choice for age-related research. The existence of an age-related retinal degeneration was reported previously in the males of this strain, but a gender comparison has not been performed. In this study, histological and morphometric measurements of the retina related to age, retinal topography, and gender were made on 3- to 24-month-old animals. The thicknesses of the outer nuclear layer (ONL) and the photoreceptor layer (PRL) were measured from sagittal sections at six loci. Retinas of both sexes showed steady decline with age in the thicknesses of the ONL and PRL at all locations. An important finding was the presence, after 12 months of age, of a drastically accelerated rate of peripheral retinal degeneration seen only in male subjects. Females showed a less dramatic rate of peripheral degeneration which did not begin until after 18 months of age. In addition, two other forms of retinal degeneration were found--cystoid degeneration was found earlier and more frequently in the male, while a paving-stone type of degeneration was found in both sexes. These two types of lesions were preferentially, but not exclusively found in the peripheral retina. In conclusion, the F344 rat offers a convenient model to study a pattern of retinal degeneration affected by the combination of gender, regional and age-related factors.

A new procedure for fundus photography and fluorescein angiography in small laboratory animal eyes

Increasing interest in retinal research demands continuous improvement of experimental techniques and interpretation. Thus, the purpose of our research was to devise a new method for funduscopic photography and fluorescein angiography in the normal or diseased retina of the small laboratory animal that would produce results comparable in optical quality and field coverage to those obtained in human clinical practice. To enhance the view of the small eye, a 2.2 Volk Panretinal lens was held in apposition to the lens of a clinical fundus camera, the Topcon TRC 50FT, by means of a custom made metal sleeve. Albino mice, albino rats, and pigmented rats were photographed. Fluorescein angiography was performed on pigmented rats. Fluorescein was administered intravenously via the jugular vein at a dose of 5 mg/kg. Various speeds of film and flash settings were used depending on the light source and the pigmentation of the animal. Attachment of the 2.2 Panretinal lens to the clinical fundus camera allowed for more clearly defined fundus photographs of the small laboratory animal, as well as an enlarged field of observation over conventional techniques. Consequently, angiography fields and stages documented in the small laboratory animal approximated those obtained in human clinical practice. This technique facilitates the visualization of small fundi and it allows for a fuller documentation of experimental retinal models.

Chapter 16 Retinal transplants into adult eyes affected by phototoxic retinopathy

Publisher Summary This chapter discusses retinal transplants into adult eyes affected by phototoxic retinopathy. This chapter also discusses : (1) whether, and to what extent, the adult retina would support the growth and differentiation of the immature retina beyond the implantation point; (2) whether the photically damaged host retina would provide vascularization sufficient to allow extended growth of the transplant; (3) to what extent the transplant would integrate with the host neural retina; and (4) whether eyes with extensively damaged retinas would also be able to incorporate transplanted cells and to support their growth. The results indicate that successful retinal transplantation is feasible into the extensively damaged adult eye, and that to some extent, the procedure permits the repopulation of neuroretinal cells. There are some similarities and fundamental differences between the experimental designs used and the results described in the present report. The main similarity is the ability for the transplanted retina to survive, grow and differentiate into the adult host eye, while the most significant difference is that in the present study, the hosts eyes are not normal, rather suffer from extensive neural and vascular damage to retina and choroid. However, the use of labeled, dissociated cells, in addition to tissue strips, added a technical advantage to the experimental protocol.

Neither intraocular grafts of retinal cell homogenates nor live non-retinal neurons produce behavioral recovery in rats with light-damaged retinas

Previously we have observed that fetal retinal cells grafted to the subretinal space of blind rats produced a functional recovery as determined by testing the visual inhibition of the startle response. Following those studies, we performed experiments to test whether the injection itself, cell by-products, or unrelated neural cells could also produce an effect. Visual function was tested by examining the inhibitory effect of a brief light flash (300 lx) on the acoustic startle response to an immediately following intense noise burst in light blinded Fischer 344 rats. Animals were tested before and after grafts of fetal retinal cell homogenates, dissociated perinatal cerebellar cells, and sham injections in the subretinal space. Behavioral testing continued every 2 wk for 14 wk after the graft. In the pretests, the light flash inhibited the startle response, maximal at intervals of 40-70 ms with recovery thereafter. In contrast, after exposure for 4 wk to fluorescent light (300 lx) and a rest in a normal 12/12 h light/dark environment the rats showed reflex facilitation to the light, maximal at an interval of 110 ms, followed by a late period of reflex inhibition. The light flash had no effect on other rats that had been blinded by bilateral enucleation. Light blinded animals receiving either cerebellar grafts or retinal cell homogenates were no different in performance from their sham injected control animals. The present data suggest that neither subretinal injections of neural cells nor non-specific neurochemical factors are able to elicit a positive behavioral response in visually impaired animals.

Photoreceptor differentiation in retinal xenografts of fetal monkey retina

Although the potential of retinal grafts to provide the host eye with rod cells is presently well established, the possibility of grafting cone photoreceptors has not been documented. In this study, the neural retinas of two Cebus apella monkey fetuses were xenografted into immunosuppressed Fischer 344 adult rats. Histological analysis showed intimate apposition between the grafted donor cells and the neighboring host rat retina. The transplanted cells survived well and often overgrew the boundaries of the host retina, expanding into the host vitreous cavity. These cells formed histogenetically differentiated structures predominantly populated by the photoreceptors. When transplanted into a foreign environment, donor cells formed inner segments which exhibited the basic morphology of cells developed in situ. This study demonstrates that embryonic monkey neural retina is a viable source of xenograft material. It also indicates that an advanced embryonic stage is not a deterrent to survival and differentiation of grafted primate neuroretinal cells. The successful transplantation of these cells, especially under the relatively adverse conditions of a xenograft, raises the hope that retinal transplantation may in fact be a useful technique for repairing both rod and cone function in damaged retinas of higher animals including humans.

Congenital retinitis in the rat following maternal exposure to lymphocytic choriomeningitis virus

A combined clinical and histopathological study of the eyes of the offspring of females inoculated with LCMV shows that about two-thirds of the pups develop some degree of retinal inflammation. This may range from a mild, subclinical reaction to an overt retinitis characterized clinically by demonstrable inflammatory and degenerative changes. Histopathologically, the latter condition presents the picture of an inflammatory reaction with extensive loss of photoreceptors and retinal neurons in general, macrophagic invasion, mild microcystoid degeneration and total or subtotal retinal detachment. This vertically-transmitted disease does not show the relentless progression and hemorrhagic tendency characteristic of the retinitis which occurs after direct viral inoculation. However, in the most severe cases the final outcome is the same, namely severe retinal impairment subsequent to widespread loss of photoreceptors. In the presence of consistently negative virological data, the hypothesis is proposed that this retinitis could be the result of a vertically-transmitted autoimmune disease.

The Eger Macular Stressometer: Pilot study

PURPOSE To evaluate the sensitivity of the Eger Macular Stressometer (EMS) for early screening of age-related macular degeneration (AMD) in a clinical practice. We examined the null hypothesis that AMD eyes have EMS recovery times (RTs) that do not differ from eyes with cataract, diabetic retinopathy, or glaucoma. DESIGN The design of this study was a nonrandomized clinical trial. METHODS Ninety-two eyes from 92 patients with vision 20/80 or better, age 50 and older, of either gender, and any ethnic origin, were recruited into one of four groups: AMD (30 eyes), normal or mild cataract (30 eyes), diabetic retinopathy (16 eyes), and glaucoma (16 eyes). Recovery times were obtained with the EMS, according to manufacturers instructions. RESULTS The mean (SD) [median] RT for the AMD group was 11.8 (7.6) [9] seconds, the normal/cataract group 10.0 (4.3) [9] seconds, the diabetic retinopathy group 8.4 (3.0) [8] seconds, and glaucoma group 8.6 (2.4) [8] seconds. Recovery time did not appear to be related to group (P =.58), age (P =.50), visual acuity (P =.52), or sex (P =.23). CONCLUSIONS We found EMS RT distributions did not differ between AMD, cataract, diabetic retinopathy, and glaucoma groups. The EMS in its current form is not a sensitive screening tool for AMD. Further testing is needed to examine EMS sensitivity with other macular diseases such as central serous choroidopathy and diabetic macular edema.

Ocular complications of the Wada test

The injection of sodium amobarbital into the internal carotid artery (Wada test) is used preoperatively to identify the dominant hemisphere and to evaluate the possible effects of temporal lobectomy on speech, language, and memory. Although transient ocular side effects of the Wada test have been described, we present two cases of permanent ocular complications, consistent with a toxic reaction to sodium amobarbital.