Stimulation of lens regeneration from the newt dorsal iris when implanted into the blastema of the regenerating limb

Dorsal iris from the eyes of adult Notophthalmus viridescens was transplanted into the blastema of regenerating limbs, subcutaneously in the limb or shoulder region, into the dorsal fin of larval newts and into the hindbrain of larval Ambystoma maculatum. The iris implants into the blastema regenerated lens vesicles or lenses with fibers in 40–75% of the cases. Multiple lenses were found in a few instances. No lenses developed from iris implants into the dorsal fin. Twenty percent of subcutaneous implants of iris formed lenses or lens vesicles, but lens regeneration from implants into the brain occurred only rarely. Denervation of the limb at the time of iris transplantation into the blastema greatly reduced the number of lenses regenerated. Studies on nerve fiber distribution in dorsal fin, subcutaneous areas, and denervated and innervated regenerating limbs, using the Bodian method, showed a general correlation between density of nerve fibers in the implant site and the incidence of lens regeneration from iris implants into that site. These results provide some evidence for a trophic action of nerve fibers on lens regeneration from the iris.     

Iris recognition as a biometric method after cataract surgery

Background

Biometric methods are security technologies, which use human characteristics for personal identification. Iris recognition systems use iris textures as unique identifiers. This paper presents an analysis of the verification of iris identities after intra-ocular procedures, when individuals were enrolled before the surgery.

Methods

Fifty-five eyes from fifty-five patients had their irises enrolled before a cataract surgery was performed. They had their irises verified three times before and three times after the procedure, and the Hamming (mathematical) distance of each identification trial was determined, in a controlled ideal biometric environment. The mathematical difference between the iris code before and after the surgery was also compared to a subjective evaluation of the iris anatomy alteration by an experienced surgeon.

Results

A correlation between visible subjective iris texture alteration and mathematical difference was verified. We found only six cases in which the eye was no more recognizable, but these eyes were later reenrolled. The main anatomical changes that were found in the new impostor eyes are described.

Conclusions

Cataract surgeries change iris textures in such a way that iris recognition systems, which perform mathematical comparisons of textural biometric features, are able to detect these changes and sometimes even discard a pre-enrolled iris considering it an impostor. In our study, re-enrollment proved to be a feasible procedure.

     

Influence of the pituitary on Wolffian lens regeneration

Removal of the pituitary 3 days before lentectomy retards Wolffian lens regeneration in the adult newt, Notophthalmus viridescens, by two stages over a 21-day period. Hypophysectomy 5 or 10 days after lentectomy does not alter the progress of regeneration during the subsequent 10-day period. Hypophysectomy 3 days before lentectomy also significantly decreases the incorporation of [³H]thymidine by iris epithelial nuclei 5 days after lentectomy but has no statistically significant effect on the incorporation 7 days after lentectomy.Pituitary tissue from newts or frogs enhances the regenerative activity of newt iris epithelial cells in vitro and in many cases promotes lens fiber formation. To a lesser extent, other tissues, such as nerve ganglion, also enhance the production of lens fiber cells from iris epithelium in vitro, whereas muscle tissue does not; and under certain conditions iris epithelial cells were found to depigment and redifferentiate into lens cells in the absence of other tissues in vitro.     

Transformation of Iris into Lens in vitro and its Dependency on Neural Retina

Upon lentectomy of adult newt eyes, the dorsal iris epithelium produces a cell population that develops into a new lens. The tissue transformation can be completed not only in the isolated lentectomized eye cultured as a whole, but also in the isolated newt normal dorsal iris combined with the retina of frog larvae in vitro. In this study, 93% of such cultures produced lens tissue made up of newt cells. Well-differentiated lens fibre cells were formed which showed positive immunofluorescence for gamma crystallins. When the isolated dorsal iris epithelium was cultured under the same conditions, well-differentiated lens tissue was again formed in 95% of the cases, suggesting that iris epithelial cells and not iris stromal cells are responsible for lens formation. In contrast, the combination of newt ventral iris with frog retina did not produce any newt lens tissue. No lens tissue was produced when the dorsal iris was cultured with newt spleen or lung, although a considerable number of iris epithelial cells became depigmented. Isolated normal dorsal iris or normal dorsal iris epithelium cultured alone infrequently produced a population of depigmented cells but failed to form lens tissue. On the basis of the present and earlier data, it is concluded that in Wolffian lens regeneration in situ , interaction of the iris epithelial cells with the retina plays a decisive role. However, it is suggested that the iris epithelial cells may have an inherent tendency towards lens formation, and that the factor(s) from the retina facilitates the realization of this tendency, rather than instructing the cells to produce lens. The reported experiments provide the first direct evidence for the existence of cellular metaplasia by demonstrating transformation of fully differentiated iris epithelial cells into lens cells.     

Ocular prosthesis for a geriatric patient with customised iris: a report of two cases

doi:10.1111/j.1741‐2358.2009.00327.x
Ocular prosthesis for a geriatric patient with customised iris: a report of two cases Objective: An ocular prosthesis is given when trauma or disease may lead to enucleation or evisceration of the eye and the combined efforts of the ophthalmologists and the maxillofacial prosthetist can provide a cosmetically acceptable ocular prosthesis. Methods: An ocular prosthesis is either pre‐fabricated or custom‐made. One of the important factors for achieving a cosmetic result is accurate colour matching of the iris with the contralateral iris. Results: A knowledge of the anatomy of the eye facilitates hand painting of iris and sclera to produce a satisfactory result. Conclusion: The custom‐made ocular prosthesis allows infinite variations during the fabrication.     

Cellular Studies of X-Ray Induced Inhibition of Lens Regeneration

Whole-body X-irradiation of adult newts 0 to 3 days after lentectomy inhibits transformation of the dorsal iris epithelium into a lens in all cases. The first question raised was whether irradiation affects infiltration of the iris area by macrophages, and the phagocytic activities of these cell types in the iris epithelium (prominent phenomena in this system). The number of macrophages infiltrating into the iris epithelium, and their phagocytic activities (indicated by uptake of melanosomes) were not affected by irradiation under those conditions. The second group of experiments concerns the possible effects of irradiation on DNA replication of iris epithelial cells, which become transformed into lens cells in the non-irradiated system. Autoradiographic studies of iris epithelial cells in vivo revealed a significant suppressive effect of irradiation on the frequencies of cells incorporating ³H-thymidine 7 and 14 days after lentectomy. When autoradiography was applied to the primary pure culture of iris epithelial cells at different time intervals after the start of culture and irradiation in vitro , significant and persistent reduction of cell labelling due to irradiation, was demonstrated. Multiplication of spread cells in the iris epithelial culture was strongly and persistently inhibited throughout a period of 2 months. Inhibition of cell labelling and of cell multiplication was always accompanied by reduction in the extent of de-pigmentation of iris epithelial cells. De-pigmentation is one of the requirements for the cells become transformed into lens cells. The possible mechanism of radiation-induced inhibition of lens regeneration is discussed.     

Fluoroangiography of various pathological pictures in unusual observations of the anterior segment

Fluorangiography is a very important investigation in order to have a differential diagnosis in all pathological pattern of the conjunctiva of scleral corneal limbus of the sclera of the iris of the ciliary-body. We have in the literature two different patterns: A) Fluorescein negative pattern (cystic neoformations, benign tumors with or without pigment) B) Fluorescein positive pattern (inflammatory pseudotumors, malignant tumors). Authors agree more or less with this classification; they have, moreover, worked out some variations. In our case of a localised carcinoma, fluorescein positive, we did not observe less of fluorescein; in the iris melanoma, even this fluorescein positive, in all observed cases has shown only a small loss of fluorescein near his edges. In the other cases as in the leiomyoma and cystis we agree with the literature even with prudence.     

Iris heterochromia: variations in form, age changes, sex dimorphism]

On a sample of n = 25,346 individuals from Vienna (10,855 males, 14,491 females) the iris pigmentation has been typed by the author. In this sample 65 cases of different types of heterochromia were found. The frequency of the occurrence of the different types of this anomaly could be calculated for the first time. Neglecting age, sex, and type of heterochromia the total frequency amounts to 0.256 (males: 0.157; females: 0.37) %. The variants of heterochromia very from cases of total heterochromia to those of various size; in addition to it a number of special types could be observed. The localization of the heterochrome parts of the iris shows certain variations; mostly, however, it is seen in the lower half of the iris. The nasal part is concerned in only one case; the temporal region never. Thus, the partial heterochromia is characteristic by a marked dependency of its localization. The colour of heterochromia varies from 2 a-14 according to the Martin-Schultz standard set of coloured eyes. However, No. 9 (ca. 50%) and No. 7 (ca. 20%) were the most frequent colours. The age variations are considerable. 5/6 of all heterochromias were found between the age from 2-19 years. Finally, a marked sexual dimorphism was observed, as in females heterochromia is much more frequent than in males.     

Enhancing the Early Differential Diagnosis of Plateau Iris and Pupillary Block Using A-Scan Ultrasonography

PurposeTo distinguish the frequently misdiagnosed plateau iris eyes from pupillary block group and normal group, we compared the ocular biometrical parameters of them by A-scan ultrasongraphy.MethodsIn total, we retrospectively reviewed general characteristics and ocular findings including ocular biometric measurements of 71 normal, 39 plateau iris, and 83 pupillary block eyes.ResultsThe normal controls, plateau iris group and pupillary block group were significantly different in age, but not in gender. The anterior chamber depth tended to decrease and the lens thickness tended to increase from normal to plateau iris to pupillary block eyes. Compared to those of plateau iris group, the pupillary block group had significantly shallower anterior chamber depth (2.90mm vs. 2.33mm; p<0.001), thicker lens (4.77mm vs. 5.11mm; p<0.001), shorter axial length (23.16mm vs. 22.63mm; p<0.001), smaller relative lens position (2.28 vs. 2.16; p<0.001) and larger lens/axial length factor (2.06 vs. 2.26; p<0.001). However, when comparing plateau iris and normal eyes, only axial length and lens/axial length factor were significantly different (23.16 vs. 23.54; p<0.05 and 2.06 vs. 1.96; p<0.05).ConclusionsMeasured by A-scan ultrasonography, the ocular biometrics of plateau iris were significantly different from those of pupillary block eyes. However, our A-scan ultrasongraphy generally found no significant biometric differences between plateau iris and normal eyes. These findings suggest that while A-scan ultrasonography might be used as a practical tool for differentiating plateau iris and papillary block eyes, a more meticulous gonioscopy and other assessments may be necessary to distinguish plateau iris from normal eyes.     

Secondary lens formation caused by implantation of pituitary into the eyes of the newt,Notophthalmus

Whole pituitary glands, as well as equivalent-sized pieces of kidney, liver, and adrenal tissue, were implanted into the anterior chamber of the adult newt eye. Secondary lens formation was present in 16 out of 17 cases of the pituitary implantation experiments in which the pituitary tissues were exposed to the anterior chamber fluid. In only one case out of 23, did another implanted tissue (liver) stimulated secondary lens formation. The extent of secondary lens formation was correlated with the position (closeness) of the implant in relationship to the dorsal iris. In all cases of secondary lens formation from the dorsal iris stimulated by tissue implants, the polarity of the developing lens was reversed so that the pole of the fiber axis was directed toward the implant rather than the retina. It appears that the ectopic pituitary produces a diffusible substance capable of initiating lens formation from the dorsal margin of the iris and capable of determining the orientation of the fiber axis pole of the developing lens.     

The cell cycle of cultured iris epithelial cells: Its possible role in cell-type conversion

Cell cycle parameters were estimated in primary cultures of iris epithelial cells, obtained from explanted dorsal and ventral irises of adult newts (Notophthalmus viridescens). No significant difference was found between parameters of dorsal and ventral iris epithelial cell cultures. Compared with the total cell cycle time of iris epithelial cells in situ in the pathway of conversion, that of cultured iris epithelial cells is longer by a factor of 1.88. The results support the working hypothesis that the basic requirement for conversion of iris epithelial cells into lens cells is the passage of a definite number of cell cycles instead of the inductive influence of neural retina.     

Iris pigmentation as a quantitative trait: variation in populations of European,East Asian and South Asian ancestry and association with candidate gene polymorphisms

In this study, we present a new quantitative method to measure iris colour based on high‐resolution photographs. We applied this method to analyse iris colour variation in a sample of individuals of East Asian, European and South Asian ancestry. We show that measuring iris colour using the coordinates of the CIELAB colour space uncovers a significant amount of variation that is not captured using conventional categorical classifications, such as ‘brown’, ‘blue’ or ‘green’. We tested the association of a selected panel of polymorphisms with iris colour in each population group. Six markers showed significant associations with iris colour in the European sample, three in the South Asian sample and two in the East Asian sample. We also observed that the marker HERC2 rs12913832, which is the main determinant of ‘blue’ versus ‘brown’ iris colour in European populations, is also significantly associated with central heterochromia in the European sample.     

Enkephalin immunoreactivity in iris nerves: Distribution in normal and grafted irides,persistence and enhanced fluorescence after denervations

Summary The morphology and distribution of nerve fibers showing enkephalin-like immunoreactivity was studied in rat and mouse iris whole mounts. In adult rat, a relatively dense network of varicose fibers was seen throughout the iris. Individual, long, usually smooth fibers were observed running together with non-fluorescent fibers in bundles. Positive nerve fibers were also seen in the ciliary body and the choroid membrane. The fluorescence intensity was normally low. No enkephalin-positive fibers were detected in adult mouse iris.Extirpation or lesioning either one or all the three ganglia known to supply the rat iris with nerve fibers, the superior cervical, the ciliary and the trigeminal ganglia, caused no detectable decrease in amount of enkephalin-positive fibers. However, in irides grafted to the anterior eye chamber of adult recipients, no enkephalin-positive fibers could be observed 2–12 days postoperatively, strongly suggesting that degeneration of these fibers had occurred. When iris grafts were left longer in the eye, nerve fibers with enkephalin-like immunoreactivity reappeared. An increased fluorescence intensity was observed both in the ipsilateral and contralateral iris following extirpation or lesioning all three ganglia and in the ipsilateral iris after extirpation of the ciliary ganglion. Three days after a systemic injection of capsaicin, which causes a permanent disappearance of substance P fibers, the same phenomenon was often observed. This raises the possibility of an interaction between the enkephalin-positive and the substance P fiber systems in the iris.The present experiments thus demonstrate a rich network of enkephalin immunoreactive nerve fibers in the rat iris originating outside the iris but apparently not in the ciliary, trigeminal or superior cervical ganglion.     

THE POTATO TUBER NEMATODE, DITYLENCHUS DESTRUCTOR THORNE, 1945; THE CAUSE OF EELWORM DISEASE IN BULBOUS IRIS

For about twenty-five years a fairly widespread disease of bulbous iris has been known, the cause of which has always been attributed to a biologic race of the stem eelworm Ditylenchus dipsaci (Kühn, 1857), Filipjev, 1936.
Thorne (1945) showed that the nematode causing rot in potato tubers is different from D. dipsaci and named it D. destructor. This nematode has since been reported from Mentha arvensis L. by Hurst (1948) and from Sonchus arvensis L. by Goodey & Goodey (1949).
Examination of nematodes from diseased iris bulbs showed them to possess rounded tail tips and six incisures on each lateral field; characters by which Ditylenchus destructor is distinguished from D. dipsaci.
Cross-inoculation experiments showed that the eelworm causing disease in potato tubers would invade and set up characteristic symptoms in iris bulbs and, in the opposite direction, the eelworm responsible for disease in iris bulbs would give rise to characteristic symptoms in potato tubers. Transfer was also effected from potato and iris to Mentha arvensis and from iris to Sonchus arvensis.
The history of the disease in bulbous iris is briefly reviewed and the biology of Ditylenchus destructor discussed and compared with that of D. dipsaci.
The conclusion that D. destructor is the nematode causing eelworm disease of bulbous iris has been reported earlier (Goodey, J. B. 1950).     

Embryonic origin of skeletal muscle cells in the iris of the duck and quail

Summary The origin of skeletal muscle cells in avian iris muscle was investigated by quantitative analysis of heterochromatin profiles at the electron-microscopic level in irides of six types of quail-duck chimeras. Each of the following tissues was transplanted into the head region from quail to duck between stages 9 and 10: cranial neural crest; trunk neural crest; midbrain and adjacent mesoderm; forebrain; forebrain without neural crest; and forebrain without neural crest and mesoderm. The average ratio of heterochromatin profile to nucleus profile in iris skeletal muscle cells was high (quail type) in the dorsal iris, but low (duck type) in the ventral iris of the chimeras resulting from isotopic transplantation of cranial neural crest. Heterotopic transplantation of trunk neural crest to cranial position resulted in failure of development of skeletal muscle cells in the dorsal iris, but not in the appearance of skeletal muscle cells in the ventral iris. The average ratio of heterochromatin profile to nucleus profile in iris skeletal muscle cells was high in the chimeras resulting from transplantation of midbrain region and the chimeras resulting from transplantation of forebrain region, intermediate in the chimeras resulting from transplantation of forebrain region without neural crest, and low in the chimeras resulting from transplantation of forebrain region without neural crest and mesoderm. These results indicate that the skeletal muscle cells in the dorsal iris are of cranial neural crest origin while those in the ventral iris are not, and could possibly arise from cranial mesoderm.     

In vivo non-contact measurement of human iris elasticity by optical coherence elastography

Quantifying the mechanical properties of the iris can offer valuable insights into the pathophysiology of primary angle closure glaucoma. However, current techniques for iris elastography remain ex vivo with limited clinical applications. This article describes a proposition for a non-contact and non-invasive air-puff optical coherence elastography (OCE) system that can evaluate iris elasticity in vivo. Ten eyes recruited from seven subjects underwent OCE imaging acquisition under three different illumination conditions. The Young's modulus of each eye was detected and shown to be inversely proportional to the iris length, indicating a relationship between mechanical properties and morphology of the iris. With its noninvasive and high-resolution features, this air-puff system shows great potential for applications in clinical ophthalmology.     

Direct evidence for transformation of differentiated iris epithelial cells into lens cells

Although it is generally assumed that the lens regenerated in the newt eye after complete lentectomy is formed by cells derived from the dorsal iris epithelium, experimental evidence so far obtained for this transformation does not rule out participation of cells from the dorsal iris stroma. When the normal dorsal iris epithelium of adult Notophthalmus (Triturus) viridescens was isolated and cultured in the presence of frog retinal complex, newt lens tissue was produced in 88% of cultures. These lens tissues were positive for immunofluorescence for lens-fiber-specific gamma crystallins as well as for total lens protein. On the basis of a study of stromal cells contaminating the samples of dorsal iris epithelium and a test for the lens-forming capacity in vitro of the dorsal iris stroma in the presence of frog retinal complex, it is concluded that lens formation observed in the above experiment is not dependent on the contaminating stromal cells. This implies that, in Wolffian lens regeneration, fully differentiated adult cells completely withdrawn from the cell cycle are transformed into another cell type. An additional culture experiment demonstrated that lens-forming capacity is not restricted to the dorsal half of the iris epithelium, but extends into its ventral half.     

Congenital hemihypertrophy. Tendency to association with other abnormalities and/or tumors

Nine cases of congenital hemihypertrophy of an entire half of the body ("true" hemihypertrophy) were investigated in relation to literature data. The left side was more often affected (7:2) and the abnormality was more frequent in females (5:4). Associated abnormalities were present in all cases: a single abnormality in 3 cases (mental retardation, iris heterochromia and, respectively, left foot gigantism) and 3 to 13 abnormalities in the other 6 cases. Prominent hemiface, asymmetric macroglossia on the affected side, unequally developed breasts, unilateral gigantism of the foot, iris heterochromia, duplication of the renal pelvis, were considered important signs which easily draw attention. Out of nine cases investigated, three presented associated tumors: two tumors, one cerebral (malignant ependymoma) and the other hepatic (cavernous hemangioma) in one case, hepatoblastoma in another case, and multiple skin angiomas in the affected side of the third one. The case presenting two tumors had also the greatest number (twelve) of associated abnormalities.