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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.

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.

Evaluation of the clinical, epidemiological and cost aspects of contact lens related infectious corneal ulcers requiring hospitalisation.A retrospective analysis was performed on the files of patients hospitalised for contact lens induced corneal ulcer in the eight Belgian University Hospitals over a seven-year period (January 1997 until December 2003). For all hospitalised patients registration of the diagnosis is compulsory using the International Code of Diagnostics (ICD-9).107 patients with contact lens related corneal ulcer were included. The great majority, 99 subjects, used soft contact lenses, of which 9 were disposables, 73 planned replacement and 17 conventional lenses. Only 6 patients were night and day wearers. Three patients used daily disposable lenses. The most frequently cultured organisms were Pseudomonas and other Gram-negative germs (70%) and Acanthamoeba (16%). The majority (77%) of the corneal ulcerations were localised centrally which resulted in an average visual loss of 4 lines. In 16 patients a corneal graft was performed and one eye had to be eviscerated.Despite important technological improvements in contact lens materials and care systems, the problem of infectious ulceration has all but disappeared. On the contrary, during the study period, the number of patients hospitalised increased from 5 in 1997 to 22 in 2003, which is only partially explained by the increasing prevalence of lens wearers: 3,5% of the Belgian population in 1995 and 6,5% in 2003.

To report on the clinical, light microscopic and spectroscopic analyses of Hydroview intraocular lenses (IOLs) explanted for late postoperative IOL opacification.Retrospective study of all cases with secondary lens implantation performed at the University Hospital of Antwerp during a period of one year (2002-2003) for postoperative opacification of Hydroview IOLs. Further analyses on some of the explanted IOLs included gross and light microscopic evaluation and RAMAN spectroscopy.Lens exchange for late-onset IOL opacification was needed in seven eyes of six patients. IOL opacification became apparent between 15 and 25 months after uneventful phacoemulsification and lens implantation. Visual acuity varied from0.05 to 0.6 before explantation. In almost all cases postoperative visual acuity improved to the pre-opacification level. Light microscopic and spectroscopic analyses showed that the opacification was mainly located in the anterior portion of the IOL optic as a layer of irregular granular deposits composed of calcium phosphate.Late postoperative opacification of Hydroview IOLs may cause severe visual impairment, requiring explantation. Calcium phosphate is involved in the formation of these opacifications. Reporting on this type of complications is mandatory according to the Belgian and European directives for medical devices.

Refractieve chirurgie beoogt het beinvloeden van de refractieve eigenschappen van het oog ter correctie van een ametropie. Drie aangrijpingspunten kunnen worden gehanteerd: de cornea, de lens en de sclera. In deze bijdrage wordt vooral aandacht geschonken aan de ingrepen door middel van lasertechniek ter hoogte van de cornea en aan de toepassing van (intraoculaire) lenzen.

Implantation of a phakic anterior chamber lens has few complications. However in one case out of 46 implanted eyes we observed a detachment of the iris claw haptic and destruction of iris tissue with a consequent transparent defect. Complications of this type of phakic anterior chamber lenses and their management will be discussed.

The fact that laser treatment is effective in diabetic retinopathy has been proven clinically. Laser photocoagulation is by no means a treatment of the disease as such, but only an indirect way to control the ocular complications of the disease. Besides regulation of glycemia it is the only therapeutic tool in the hands of the ophthalmologist. However routinely used in clinical ophthalmology, the basic principles of the treatment need to be understood by the user. The best way to do so is to use the experimental approach. This paper summarizes the various experimental techniques used to understand and to study the interaction retina-laser: histology, electron microscopy, immunocytochemistry and in vivo microdialysis.

We reviewed the medical records of 30 eyes of 27 patients needing Nd-YAG laser capsulotomy for posterior capsular opacification after extracapsular cataract extraction using the phaco-emulsification technique with anterior continuous circular capsulorhexis. Associated ocular and/or systemic disorders were reported and the possibility of preselection of patients at risk for posterior capsular opacification and their eligibility for posterior circular continuous capsulorhexis will be emphasized.

Twenty-eight eyes were followed for at least 6 months after phacoemulsification, posterior capsulorhexis and intracapsular lensimplantation. No case of clinical significant macular edema, retinal tear or retinal detachment was noted during this period.

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.

A case is presented with irreversible blindness in one eye and restriction of the infratemporal visual field in the other eye, due to electrocoagulation performed for delayed bleeding after functional endoscopic sinus surgery (FESS). Although blindness due to rhinosurgery is a well-known, but rare complication, a review of the recent literature did not reveal a similar incident. The use of electrocoagulation especially under conditions of poor visualization, that may be the case in post-operative bleeding following (endoscopic) sinus surgery, is strongly discouraged.