Search

Tyrosinase in crude extracts from the adult rabbit choroid and retina/retinal pigment epithelium was found to be differently affected by the inhibitors sodium metabisulfite, cyanide, diethyldithiocarbamate and 2,2'-dipyridyl:the latter inhibited the activity in the retina/retinal pigment epithelium extract after 24 hr of incubation, but not that in the choroid. The first three inhibitors, on the other hand, inhibited the activity in the choroid extract, but not in the retina/retinal pigment epithelium extract, after 3 hr of incubation. Both extracts contained one insoluble and two soluble isoenzymes. The mobilities and the apparent molecular weights of the soluble isoenzymes (more markedly so for the most rapidly migrating) differed, as revealed by polyacrylamide gel electrophoresis, resulting in distinct isoenzymic patterns. We suggest that such patterns may be related to the characteristic melanogenic features of the retina/retinal pigment epithelium and choroid.

The incidence of iris melanoma is 8% of all the uveal melanomas.1 In children and adolescents, iris melanoma accounts for 0.6–1.6% of all the uveal melanomas.2 We present a case of iris melanoma in a young boy treated with iridectomy and a phakic iris repair implant lens. A 12-year-old boy was referred to the Department of Ophthalmology, Antwerp and then to Leiden because of a melanocytic lesion on the right iris without complaints. The visual acuity was 20/20 in both the eyes. Slit-lamp examination showed a pigmented iris lesion in the inferior quadrant of the right eye with diameter of 6.8 mm. The pupil showed a visible deformation, and an abnormal vasculature was present with ectropion uvea (figure 1A). Gonioscopy revealed a flat pigmented lesion extending in the open anterior chamber angle. …

Resume Objectif Evaluer l’interet de l’implant « bag-in-the-lens » chez des enfants operes de cataracte. Patients and methodes Cette etude prospective inclut 54 yeux de 37 enfants consecutifs, âges de 2 mois a 14 ans, operes de cataractes unilaterales ou bilaterales avec implantation de la lentille intraoculaire « bag-in-the-lens » entre decembre 1999 et janvier 2008. L’examen sous lampe a fente, la pression intraoculaire, l’acuite visuelle et la refraction ont ete suivis au cours du temps dans la mesure du possible. Resultats L’âge moyen des 37 enfants a la derniere consultation etait de 8,3 ± 4,9 ans. L’acuite visuelle moyenne est passee de 0,2 ± 0,1 a 0,8 ± 0,3. En revanche, la recuperation de l’acuite visuelle chez les enfants presentant une persistance hyperplasique du vitre primitif n’a pas ete aussi importante, avec une acuite visuelle postoperatoire moyenne de 0,14 ± 0,18. La refraction moyenne postoperatoire chez les 13 enfants (26 yeux) operes de cataractes bilaterales etait de 0,5 ± 1,5 D pour des yeux dont les longueurs axiales etaient tres disparates. La refraction etait stable au cours du temps chez les enfants de plus de 2 ans. A partir du moment ou l’implant a ete correctement positionne, les cellules epitheliales du cristallin restantes n’ont pas migre vers l’aire visuelle ; ce qui a ete le cas dans 93,8 % des yeux et chez 100 % des enfants âges de plus de 1 an. Conclusions L’implant « bag-in-the-lens » est particulierement indique chez les enfants chez lesquels le rhexis posterieur et la capture de l’optique sont deja preconises depuis 1994. Son implantation minimise le recourt a la vitrectomie anterieure dans la chirurgie de la cataracte chez l’enfant.

Rabbit retinas were treated with low-intensity laser coagulation at five different wavelengths. Using an indirect immunocytochemical method, the retinas were stained for glial fibrillary acidic protein (GFAP) at 2, 4, 21 and 32 days after coagulation such that we could follow GFAP expression in the Müller cells during retinal repair. GFAP-positive staining was found in the end feet of the Müller cells at 2 days after laser coagulation. GFAP immunoreactivity was observed throughout the Müller cells, surrounding the central necrotic tissue, at days 4, 21 and 32 after laser coagulation. Scar tissue in the subretinal space at days 21 and 32, which was more pronounced for the longer wavelengths produced by the Krypton and Nd-YAG lasers, also showed GFAP immunoreactivity. The Müller cells remained GFAP-immunoreactive for at least 32 days after laser coagulation.

The indications for two types of pulsed Nd: YAG lasers in the treatment of vitreous pathology are reviewed. A series of 94 eyes from 93 patients were treated with the mode-locked system and 72 eyes from 71 patients were treated with the Q-switched system. A classification of vitreous pathology with prognostic value for the efficacy of treatment of both lasers is established. For the Q-switched laser the range of indications in the posterior pole is larger and fewer sessions are needed; however, complications are more frequent than with the mode-locked laser. This difference is due to the higher energy needed with the Q-switched laser to treat more severe vitreous pathology.

Rabbit retinas were treated with laser coagulations of low intensity, using five different wavelengths. After coagulation (1, 4 and 28 days), the retinas were stained for GABA, using a direct biotinavidin-horseradish peroxidase immunocytochemical method. These time intervals were chosen with regard to the existing knowledge of retinal repair. The staining for GABA was increased in the inner plexiform layer at the centre of the lesions at days 1 and 4 after coagulation. At the margins of the lesions, cells in the ganglion cell layer showed strong staining and cells in the amacrine cell layer showed cuffing, independent of the wavelength used. On day 28, a regression of the hyperstaining was noted. Some possible pathophysiological mechanisms are discussed.

But La premiere complication post-operatoire de la chirurgie de la cataracte chez l’enfant est l’opacification capsulaire posterieure. Cette opacification capsulaire posterieure retarde la maturation du systeme visuel et pose le probleme du traitement au laser Nd-YAG chez le tres jeune enfant. Elle arrivait classiquement dans 80 % des cas la premiere annee. Il a ete montre qu’un rhexis capsulaire posterieur retardait l’apparition d’opacification capsulaire posterieure. Ce geste chirurgical est maintenant la pratique courante en pediatrie. La lentille « bag-in-the-lens » permet, apres un double capsulorhexis, d’inserer les capsules anterieures et posterieures dans le sillon de l’implant pour contenir les cellules epitheliales du cristallin restantes afin d’eradiquer l’opacification capsulaire posterieure. Nous proposons l’analyse des performances de cette lentille intra-oculaire en pediatrie. Materiels et Methodes Quarante-huit yeux chez 33 enfants, souffrant de diverses pathologies (cataracte congenitale, traumatique ou toxique, spherophaquie, syndrome de Marfan,…) ont recu l’implant « bag-in-the-lens » entre 2000 et 2007. L’âge des enfants a la date de la chirurgie etait de 6.5 ± 5 ans (de 0 a 14 ans). Nous avons evalue les performances de cet implant en chirurgie pediatrique en termes de taux d’opacification capsulaire posterieure, de recuperation de l’acuite visuelle et de performances refractives. Resultats Le suivi actuel est de 22 ± 17 mois (0.5 a 70 mois). L’implant a pu etre correctement insere dans 47 yeux. Dans un œil (3 e cas), le rhexis capsulaire trop grand a justifie l’explantation. A partir du moment ou la capsule a ete correctement inseree dans le sillon, l’axe visuel est reste clair dans les 45 yeux (0 % d’opacification capsulaire posterieure). Discussion L’acuite visuelle moyenne quand elle a pu etre mesuree en decimale (dans 34 yeux, les 11 restants etant des patients trop jeunes ou presentant un retard mental) est 0.9 ± 0.8 (0.006 a 1). Les plus mauvaises valeurs sont celles dont l’indication etait une persistance hyperplasique du vitre primitif. Pour cette derniere population de 34 yeux, la refraction post-operatoire est en moyenne –0.7 ± 2.3 D (de 3.5 D a -7 D). Conclusion L’implant « bag-in-the-lens » permet d’eradiquer l’opacification capsulaire posterieure. Son implantation est particulierement indiquee chez l’enfant ou un rhexis posterieur est necessaire. Les performances visuelles sont bonnes. Les resultats refractifs sont inegaux du fait de la difficulte d’une mesure precise chez les enfants de moins de 3 ans.

Three eyes with preretinal macular fibrosis (PMF) were treated with the Q-switched Nd-YAG laser. The PMF was idiopathic in two eyes and associated with a vitreous hemorrhage, due to ocular trauma, in the third eye. The three eyes had in common a partial posterior vitreous detachment with vitreous traction on the macula. The Nd-YAG laser beam was focused on the detached posterior hyaloid in front of the macular region. Some holes were made in this membrane or in the adjacent collapsed vitreous cortex. Treatment increased the visual acuity in the three eyes; the vitreous remained partially detached in the two eyes with idiopathic PMF and detached completely in the eye with the secondary PMF. The disentanglement of the fovelar area was revealed by the unfolded appearance of the retinal vessels on fluoangiography.

A case is reported of a premacular retrohyaloid hemorrhage bulging into the bursa premacularis, due to a macroaneurysm secondary to hypertension. The Q-switched Nd-YAG laser is used to puncture the posterior hyaloid and drain the blood. A fast and full visual recovery is observed. The method is recommended in premacular hemorrhages without underlying proliferative diseases and where the volume of the blood does not greatly exceed 12 microliters.