Role of visual evoked potentials in the assessment and management of optic pathway gliomas in children.

OBJECTIVE: The aim of this study is to investigate the role of pattern reversal visual evoked potentials (pVEPs) in the screening and monitoring of optic pathway gliomas (OPGs) in children with and without neurofibromatosis type 1. METHODS: A review of the English literature published between 1980 and 2012 was performed, with comparison of results of retro- and prospective studies. RESULTS: Pattern reversal VEPs have a high sensitivity (85.7-100 %) for the diagnosis of OPGs, moreover they are safe and cost-effective. Conversely, they have a low specificity (43-83 %) and are not widely available. Besides, pattern reversal VEP results can be unreliable in young children, because of the need for a good cooperation. The studies that were analyzed have drawbacks, including the small sample size, the retrospective design, the differences in gold standard for diagnosis, the different interpretation of small changes in VEP results and the lack of control groups. CONCLUSION: There is still debate about the gold standard for the screening and follow-up of OPGs. The added value of pVEPs to the ophthalmic examination is controversial. Randomized controlled trials or prospective multicentre studies are necessary to assess with sufficient accuracy the sensitivity and specificity of pattern reversal VEPs in the screening for OPGs and its follow-up.

Laser-induced retinal injury following a recreational laser show: two case reports and a clinicopathological study.

BACKGROUND: Two patients who attended a dance festival with an audience-scanning laser show presented in our department with a decrease in visual acuity from a direct laser hit in one eye. Ophthalmoscopy showed a similarly sized retinochoroidal coagulation spot, which had led to a retinal hemorrhage in both patients. Because the organizers of the show concluded that the retinal injury was caused by powerful, handheld laser pointers in the crowd, we were interested in determining if these laser pointers could cause this kind of acute retinopathy. METHODS: A 44-year-old man with an extrafoveal, temporal choroidal melanoma was scheduled for enucleation. The eye (visual acuity 20/20) had a healthy-appearing macula. Prior to enucleation, the retina was exposed to eight different durations (0.5-64 seconds) of laser beam from a commercially available, handheld, class 3B green laser pointer (500 mW). RESULTS: Histologic analysis was unable to identify any abnormalities in the choriocapillaris, the photoreceptors or the retinal pigment epithelium (RPE). CONCLUSION: The use of powerful laser appliances (class 4 lasers) directed into the audience (audience-scanning laser show) can cause significant retinal injuries with lifelong visual consequences. It is unlikely that laser pointers, even those of class 3B, can cause these ocular injuries.

Preoperative eye disinfection in vitrectomy surgery using antibiotic or antiseptic eyedrops.

PURPOSE: To determine the efficacy of preoperative eye disinfection by comparing antibiotic and antiseptic eye drops. DESIGN: Prospective, randomized double-masked comparative study with three study arms: untreated, antibiotic treated and antiseptic treated. METHODS: Patients that were scheduled for vitrectomy were asked to use an antibiotic or antiseptic eye drop 4 times a day, 5 days before the surgery. Conjunctival smear was cultured at the onset of the surgery. Culture results for each study arm were compared. RESULTS: Comparable results were found in the patients treated with an antibiotic or antiseptic eye drop. CONCLUSIONS: Since an antiseptic eye drop will cause less bacterial resistance than an antibiotic eye drop, and both treatments have a similar antibacterial effect, this study indicates that prophylactic antiseptic eye drops may be preferred over antibiotic treatment, when prophylaxis is needed.

Literature review on preschool vision screening.

Amblyopia results from degradation of the retinal image during a sensitive period of visual development. Amblyopia is the most common cause of visual loss in children. Because of the failure in detection and in treatment, amblyopia is still an important cause of visual loss in adults. Results from recent randomised trials in amblyopia should change our approach to screening and treatment. Based on the current evidence, if a single screening session is used, screening at school entry could be the most efficient screening moment. Between researchers, however, there still exists a lot of controversy on the benefit of visual screening.

Systemic resorption of 5-fluorouracil used in infusion fluid during vitrectomy.

PURPOSE: The aim of this study is to determine whether 5-fluorouracil (5FU) used in the infusion fluid during vitrectomy is systemically absorbed. PATIENTS AND METHODS: The major catabolite of 5FU, alpha-fluoro-beta-alanine (FBAL) was measured in urine samples of 2 patients that underwent vitrectomy using 5FU in the infusion fluid. RESULTS: In both patients, FBAL was found in the urine samples collected up to 48 hours after the surgery, with the highest concentration and total amount in the first 6 hours after the first urine production after surgery. Moreover, the concentration and total amount of FBAL was higher in the patient who received silicone oil tamponade (versus 12.5% SF6), with the longest surgery time (40 min versus 20 min) and the highest amount of infusion fluid used (350 ml versus 250 ml). CONCLUSIONS: 5FU, used to prevent the formation of proliferative vitreoretinopathy (PVR), is systemically absorbed when used in infusion fluid during vitrectomy. As such, patient selection is needed to avoid adverse effects on procreativity. Further studies will be needed to determine which clinical setting will influence most the absorption.

Repeated bilateral retrobulbar injection of botulinum toxin in a blind patient with retinitis pigmentosa and incapacitating nystagmus.

Pronounced visual loss can lead to nystagmus, provoking oscillopsia and distressing ocular sensations. The treatment of acquired nystagmus remains difficult and various therapeutic options are attempted with limited results. We report the case of a man with acquired nystagmus and excessive ocular discomfort, successfully treated with repeated retrobulbar injections with botulinum toxin.

18 years' experience with high dose rate strontium-90 brachytherapy of small to medium sized posterior uveal melanoma.

AIM: To analyse local tumour control, radiation related complications, visual acuity, enucleation rate, and survival after brachytherapy of small to medium sized choroidal melanoma (CM) with a high dose rate (HDR) strontium-90 (Sr-90) applicator. METHODS: From 1983 until 2000, 98 eyes with CM were treated with Sr-90 brachytherapy. The main outcome measures were actuarial rates of the patients' survival, ocular conservation rate, tumour regression, complication rates, and preservation of visual acuity. End point rates were estimated using Kaplan-Meier analysis. RESULTS: The median follow up time was 6.7 years (0.5-18.8 years). Actuarial melanoma free patient survival rate was 85% (SE 4.8%) after 18 years. Actuarial rate of ocular conservation and complete tumour regression was 90% (SE 3.8%) after 15 years. In 93% local tumour control was achieved, 88% showed a stable scar. Recurrence of the tumour on the border caused enucleation of six eyes (7%). In three cases (4%) retinal detachment was the end point. No cases of optic atrophy or of sight impairing retinopathy outside the treated area were found. Actuarial rate of preservation of visual acuity of 1/10 was 65% at 5 years and 45% at 15 years of follow up (SE 5.9% and 8.8%). CONCLUSIONS: Sr-90 brachytherapy is as effective as iodine or ruthenium brachytherapy for small to medium sized CM but causes fewer complications. The preservation of vision is better than with all other described radioisotopes. HDR Sr-90 brachytherapy can therefore safely be recommended for small to medium sized CM.

The use of a pinhole aperture during the recording of pattern reversal visual evoked potentials.

In young children, mentally retarded persons or in malingering persons, determining the optimal refraction is not always evident. Because of the importance of this optimal refraction during the recording of pattern-reversal visual evoked potentials, we tried in this study to overcome these refraction errors by the use of a pinhole.

(Hydroxy)-chloroquine retinal toxicity: two case reports and safety guidelines.

Retinal toxicity as a result of antimalarial therapy has been reported for many years. Retinopathy may be divided into reversible premaculopathy and irreversible true retinopathy. Risk factors for the development of toxicity are daily dosage related to body weight, total drug dosage and the specific drug used. The daily dosage of chloroquine should not exceed 4 mg/kg lean body weight a day. Exceeding the total dosage of 300 g increases the risk. The daily dosage of hydroxychloroquine should not exceed 6.5 mg/kg lean body weight a day with increased risk when the duration of treatment exceeds 8 years (1330 g for a patient of 70 kg). Regular dilated fundus examination, visual field testing using Amsler grid test and automated central 10-2 perimetry (to a red test object) is advised to detect reversible premaculopathy. Hydroxychloroquine toxicity due to excessive cumulative dosage is discussed in case 1. Chloroquine toxicity due to excessive daily dosage is discussed in case 2.

Ocular emergencies in Kinshasa (Democratic Republic of Congo).

PURPOSE: To determine frequencies of ocular emergencies and identify their nature. DESIGN: Observational case series. METHODS: In a retrospective study, the records of all 118 consecutive patients seen in emergency room during an eleven-month period were reviewed. RESULTS: Ocular emergencies represented 4% of the 2917 new patients visiting the department of Ophthalmology during this time. There was a 2.1/1 male to female preponderance and a peak age of presentation between 11 and 30 years. The mean age was 26 years +/- 17. Ocular trauma (68 patients) accounted for over two-fourths (57.6%) of the total cases. Only 16% of patients presented within 48 hours. Fifty-one percent of injuries occurred to the left eye, 38% to the right, and 10% bilaterally. The commonest ocular injury problems were eyelid laceration (13 patients, 19.1%), post-traumatic iritis (12 patients, 17.6%), and corneal laceration and penetration (10 patients, 14.7%), accounting for 51% (35 patients) of the total. Home- and work-related ocular injuries accounted for 54% of all ocular injuries. Thirty-three percent of all ocular injuries were caused by assault and fight, and 15% were related to motor vehicle accident. For the non-traumatic ocular emergencies, the main aetiological factor was inflammation (18%). CONCLUSION: Our study showed that males account for the majority of eye injuries and this class is more prone to assault-related injuries. In our country prevention strategies must take account of these.

Short-term intra-individual variability in heidelberg retina tomograph II.

We determined the short-term intra-individual variability for each parameter of the Heidelberg Retina Tomograph II (HRT II). Therefore we examined prospectively 20 healthy volunteers 3 times within 2 weeks. The variability was expressed as the coefficient of variation for each parameter. The short-term intra-individual variability in normal subjects was < or = 12% in all but 3 parameters. Rim Area was the least variable parameter (2 +/- 1%). Cup Volume had the highest variability (25 +/- 38%).

Recording of the fast oscillations in the human electro-oculogram.

The fast oscillations (FO) of the electro-oculogram were recorded in 102 eyes of 51 normal subjects. We evaluated the normal range and variability of FO parameters, i.e. Rf, which is the average ratio in percentage of the average amplitude in the dark period (AD) and the average amplitude in the light period (AL), and df, which is the average difference between AD and AL in microV. The standing potential was recorded continuously during six subsequent cycles, each consisting of a one minute period in the dark and one minute period in the light. The mean +/- standard error for Rf was 112.9 +/- 1.3% and 69.6 +/- 5.3 microV for df. There was no statistically significant difference between both genders or different age groups. Rf and df were calculated using a different number of dark-light cycles. In normal subjects both the Rf and df show no difference when only 4 dark-light cycles are used in calculating these values. Therefore there seems no additional advantage in performing as many as 6 cycles. Using 4 dark-light cycles reduces the duration of the examination (8 vs. 12 min) of the fast oscillations and in particular when examining both fast and slow oscillations successively it might be useful to reduce the time of the examination.

Clinical and electrophysiological findings in autosomal dominant vitreoretinochoroidopathy: report of a new pedigree.

PURPOSE: To report the clinical and electrophysiological findings in a three-generation pedigree with autosomal dominant vitreoretinochoroidopathy. METHODS: Sixteen members of a three-generation pedigree with autosomal dominant vitreoretinochoroidopathy were examined clinically, including measurement of the corneal diameter. In 14 persons, Goldmann perimetry, axial length determination and electro-oculography were carried out. Electroretinography, according to ISCEV standards, was performed in 11 of 12 affected persons. RESULTS: Characteristic annular peripheral pigmentary changes were present in all affected members, as well as chorioretinal atrophy varying from a tigroid aspect to marked atrophy. Four patients presented a microcornea and shallow anterior chamber without microphthalmia. The visual fields appeared to narrow with ageing. The electro-oculography was pathological in the affected patients and normal in the unaffected. The electroretinographic amplitude responses tended to worsen with age, with maintenance of near normal latencies. CONCLUSION: The clinical presentation of autosomal dominant vitreoretinopathy is variable. Electrooculography seems to be a discriminative test. The condition may be associated with anterior segment abnormalities other than presenile cataract, such as microcornea, shallow anterior chamber and angle closure glaucoma.

Different strategies for Humphrey automated perimetry: FASTPAC, SITA standard and SITA fast in normal subjects and glaucoma patients.

PURPOSE: To evaluate the influence on examination time and test quality of the recently introduced SITA strategies of the Humphrey Field Analyzer. METHODS: The sample consisted of 41 subjects (19 normal subjects and 22 glaucoma patients), all experienced in automated perimetry, ranging in age from 24 to 83 years. One eye of each patient was examined with the HC30-2 program using the FASTPAC (FP) and SITA Standard (SS) or SITA Fast (SF) strategy on the same day, in random order. Examination time was evaluated as a function of the strategy. To evaluate the test quality both regional and global visual field parameters were analyzed. Global parameters included mean deviation (MD) and pattern standard deviation (PSD). Regional parameters (mean and maximum loss) were calculated to estimate the extent and the depth of localized visual field defects. For this purpose each visual field was divided in 4 quadrants and in 10 clusters as defined in the glaucoma hemifield test. RESULTS: 1. There is a considerable test time reduction from FASTPAC over SITA Standard to SITA Fast for comparable MD and PSD values. On average, the SITA Fast test duration is half that of the FASTPAC procedure. For each strategy, the test duration increases for increasing visual field loss. 2. Between all three strategies, there is a good correlation for the global indices (MD, PSD) 3. For the regional indices (mean loss, maximum loss) the same high correlation exists. CONCLUSION: The SITA strategy causes a significant test time reduction without decreasing the test quality.

Unusual retinal vasculitis in a patient with protein S deficiency and systemic toxoplasmosis: a case report.

A 28-year old female patient presented with unilateral dropped visual acuity and a central scotoma. Fundus examination and a fluorescein angiogram were suggestive for central retinal vein prethrombosis. Further tests revealed an isolated protein S deficiency for which oral anticoagulation therapy was initiated. Six months later she presented with new symptoms of a right retrobulbar pain on ocular movements. The retinal vessels had normalized with improved visual acuity. Re-evaluation of the fluorescein angiogram taken six months earlier showed an image compatible with unilateral vasculitis. During this six month period persisting high levels of IgG and IgM antibodies against Toxoplasma were observed while no signs of other active infection could be found. This report illustrates that in cases of prethrombosis with vasculitis in a young patient, a full medical examination and a thorough investigation of infectious diseases are warranted.

OCT study of fellow eyes of macular holes.

The aim of this study was to examine the vitreomacular interface in symptom-free fellow eyes of macular holes using optical coherence tomography (OCT) to add information to the pathogenesis of macular holes and to refine prognostic factors for bilateral involvement. Sixty-six patients with a full thickness macular hole in one eye and a symptom-free fellow eye were included in the study between 01/98-05/99. The finding on OCT that a perifoveal vitreous detachment can result in a foveal cyst and subsequently a macular hole confirms the theory of Gass of vitreous traction. Symptom-free fellow eyes with a foveal cyst on OCT represent an elevated risk (55%) for macular hole development. Vitreofoveal separation is probably a good prognostic sign.

Preliminary results of the FRO project: chromosomal abnormalities in primary uveal melanoma.

Uveal melanoma is the most common primary intraocular tumor in adults in the western world. Recent studies indicate that the presence of cytogenetic abnormalities in tumor cells is strongly linked with prognosis. The purpose of this project is the detection of chromosomal abnormalities in a series of frozen tumors (retrospective study) and of fresh tumor tissues (prospective study) and to correlate these results with other prognostic factors and survival.

The use of optical coherence tomography in macular diseases.

With optical coherence tomography (OCT), a new technique has emerged that allows imaging of a transverse section of the retina with a resolution that has not been reached by other imaging techniques. The OCT technique can be used in the diagnosis and assessment of various diseases of both the anterior segment and the ocular fundus. This paper demonstrates that OCT can deliver useful information in the diagnosis and follow-up of several macular diseases that cannot be obtained with other fundus imaging techniques. The optical principle of OCT is based on visible-light interference. OCT allows imaging of the anatomical foveal appearance. This normal foveal appearance is disrupted when macular edema occurs, leading to thickening of the neuroretina and cyst formation. The anatomical difference between a neuro-retinal elevation and RPE elevations can be demonstrated using OCT. Epiretinal membranes and pseudo-macular holes can easily be visualized. Perhaps the most interesting addition of OCT in the retinal diagnostic field is the imaging of vitreo-macular traction syndromes and staging of macular holes, which are both difficult with ophthalmoscopy and fluorescein-angiography. Each of the above mentioned macular diseases will be illustrated by a typical case.

How to protect your eyes from solar retinopathy.

On August 11, in Belgium a solar eclipse will occur which will be total in the Southern area of the country. Although the observation of a solar eclipse is an intriguing phenomenon, inappropriate shielding from the sunlight can cause irreversible ocular lesions. Besides good absolute absorption of visible light, a blocking of ultraviolet and infrared light is equally important. In this study, four homemade sun filters were tested: a soot-blackened piece of glass, a black unexposed developed slide film, an audio-CD and a recordable CD-ROM. Also two commercially available filters were investigated: eclipse-shades and mylar foil. The soot-blackened glass and black slide film slip were highly transparent for infrared light, making them dangerous for solar observation. The recordable CD-ROM was too transparent for visible light to serve as solar filter, while the audio-CD tested absorbed enough visible, ultraviolet and infrared light to make it suitable for eclipse viewing. However, many types of audio-CD's are available making it impossible for the observer to know if a given CD is safe to use for solar viewing. Both commercially available solar filters tested had a good absolute visible light absorption, as well as an equally good absorption of ultraviolet and infrared light, making them safe for eclipse observation.

Retinitis pigmentosa in association with acromegaly: a case report.

Retinal abnormalities, unrelated to visual pathway compression, in acromegalic patients were originally described by Small in 1972 (Smail JM. Primary pigmentary degeneration of the retina and acromegaly in a case of pituitary adenoma. Br J Ophthalmol 1972; 56: 25-31). He illustrated a case of primary pigmentary degeneration of the retina occurring in a patient with a chromophobe adenoma of the pituitary gland. To the best of our knowledge this remains the sole, published case of this association. We report on two male patients, with an acromegalic appearance, one caused by a pituitary adenoma, the other associated with a Rathke's cleft cyst, presenting to our department of ophthalmology with the clinical picture of pigmentary degeneration of the retina.