The price for reduced light toxicity: Do endoilluminator spectral filters decrease color contrast during Brilliant Blue G–assisted chromovitrectomy?

Background

Vitreoretinal surgeons have been slow to adopt the use of spectral filters for endoillumination to reduce retinal light toxicity. This study shows that spectral filters can be used without a loss in color contrast during brilliant blue G chromovitrectomy.

Methods

To evaluate the influence of intra operative spectral light filters on perceivable contrast during Brilliant Blue G chromovitrectomy, a prospective, observational clinical study was carried out on 59 consecutive Brilliant Blue G chromovitrectomy interventions in 59 patients admitted for macular holes, macular pucker or vitreomacular traction syndromes. Subsequent to peeling of the internal limiting membrane, six different illumination modes were enabled consecutively: mercury vapor, mercury vapor/xenon, and xenon followed by xenon combined with an amber, green or yellow spectral filter. Main outcome measure was the chromaticity spread between stained internal limiting membrane and unstained retina as a measure for the color contrast perceived by the human eye.

Results

Mean chromaticity scores were similar for all light sources: mercury vapor 7.97, mercury vapor/xenon 7.96 (p?=?0.96), and xenon 7.41 (p?=?0.55). Compared to xenon, the additional use of endoillumination spectral filters did not change contrast recognizability: Chromaticity scores were 9.38 for the amber filter (p?=?0.13), 6.63 for the green and 7.02 for the yellow filter (p?=?0.37 and 0.64, respectively). When comparing the different filters head-to-head, the amber filter was superior to the green filter (p?=?0.03), while the yellow was intermediate and not significantly different from either the amber (p?=?0.08) or the green filter (p?=?0.51).

Conclusions

Color contrast perceptibility during Brilliant Blue G assisted chromovitrectomy is similar with mercury vapor, mercury vapor/xenon or xenon light sources. Spectral filters do not decrease color contrast recognizability. Head-to-head comparison shows a significant advantage for the amber over the green filter with respect to contrast generation, the yellow filter is intermediate. As spectral filters are known to greatly reduce retinal light toxicity, we suggest donor eye studies to validate whether the amber filter should be generally recommended for Brilliant Blue G chromovitrectomy.     

Long-term outcomes of 3 surgical adjuvants used for internal limiting membrane peeling in idiopathic macular hole surgery

Purpose

Indocyanine green (ICG), an adjuvant used for peeling of the internal limiting membrane (ILM) during vitreous surgery for idiopathic macular hole (MH), has been reported to be toxic, possibly affecting postoperative visual acuity. We compared the long-term outcomes (within 2 years) of brilliant blue G (BBG), ICG, and triamcinolone acetonide (TA).

Patients and methods

This study involved 97 eyes of 94 patients who underwent vitreous surgery for MH at the Yamagata University Hospital between June 2002 and November 2010. The surgical adjuvants used were BBG for 15 eyes, ICG for 61 eyes, and TA for 21 eyes. We compared the postoperative visual acuities, initial closure rates, final closure rates, and complications of the 3 groups.

Results

In all 3 groups, the visual acuity significantly improved after surgery. The magnitude of the improvement at 2 years after surgery was significantly better in the BBG group than in the ICG group (Mann–Whitney test, P = 0.020). The postoperative visual acuity did not significantly differ between the BBG and TA groups (P = 0.627) or between the ICG and TA groups (P =0 .137). Thus, the surgery using BBG resulted in a significantly better outcome in visual acuity than did the surgery using ICG. The 3 groups did not differ in initial or final closure rates or in incidence of complications.

Conclusion

Analysis of the long-term outcomes of vitreous surgeries provided evidence that BBG is a useful adjuvant for ILM peeling.     

Sensitivity and specificity of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen and optic disc oedema

Background

Evaluation of the efficacy of monochromatic photography of the ocular fundus in differentiating optic nerve head drusen (ONHD) and optic disc oedema (ODE).

Methods

Sixty-six patients with ONHD, 31 patients with ODE and 70 healthy subjects were studied. Colour and monochromatic fundus photography with different filters (green, red and autofluorescence) were performed. The results were analysed blindly by two observers. The sensitivity, specificity and interobserver agreement (k) of each test were assessed.

Results

Colour photography offers 65.5 % sensitivity and 100 % specificity for the diagnosis of ONHD. Monochromatic photography improves sensitivity and specificity and provides similar results: green filter (71.20 % sensitivity, 96.70 % specificity), red filter (80.30 % sensitivity, 96.80 % specificity), and autofluorescence technique (87.8 % sensitivity, 100 % specificity). The interobserver agreement was good with all techniques used: autofluorescence (k?=?0.957), green filter (k?=?0.897), red filter (k?=?0.818) and colour (k?=?0.809).

Conclusions

Monochromatic fundus photography permits ONHD and ODE to be differentiated, with good sensitivity and very high specificity. The best results were obtained with autofluorescence and red filter study.     

Evaluating retinal toxicity of a new heavy intraocular dye, using a model of perfused and isolated retinal cultures of bovine and human origin

Background

Dyes such as brilliant blue (BBG) are used during vitreoretinal surgery to visualize anatomical structures. By adding deuterium oxide (D2O), surgeons have tried to create a dye mixture heavier than water to facilitate staining of the inner limiting membrane (ILM) without prior fluid–air exchange. This study investigated the effect of 0.4?ml BBG (Fluoron, Ulm, Germany) mixed with 0.13?ml/ml D2O and D2O on retinal function of a pseudo in vivo model using bovine and human whole mount cultures.

Methods

Bovine and human retinas were superfused, and the electroretinogram (ERG) was recorded. BBG with 0.13?ml/ml D2O and D2O were applied epiretinally, different staining periods (10, 30, 60 and 120?s) were tested, and ERG recovery was monitored. 1?mM aspartate was added to the nutrient solution to examine the photoreceptor reaction.

Results

Reductions of the a- and b-wave amplitudes were found directly after exposure with BBG with 0.13?ml/ml D2O and with D2O in all test series. These effects on the electroretinogram were rapidly and completely reversible within the recovery time for all exposure times. ERG amplitudes measured after dye application at the end of the washout did not differ significantly from those recorded before staining.

Conclusions

The clinically used mixture of BBG/D2O seems to be safe for clinical use. Staining periods of more than 120?seconds were not tested.     

Brilliant Blue G as protective agent against trypan blue toxicity in human retinal pigment epithelial cells in vitro

Background

Combinations of trypan blue (TB), Brilliant Blue G (BBG) and polyethyleneglycol had been shown before to be less toxic to ARPE retinal pigment epithelial cells than TB alone. We studied systematically the influence of combinations of dyes on cell damage.

Methods

ARPE cells were exposed to TB (concentration range 0.025 to 1 %), BBG (0.0025 to 0.5 %), and combinations of the two dyes, dissolved in phosphate buffered saline (PBS), for periods between 5 and 60 min. Cell damage was monitored with the WST-1 assay. The effect of different salt concentration was measured in the same way.

Results

TB in concentrations of 0.075 % and higher was toxic to the cells already after 30 min incubation. BBG was toxic after 30 min in concentration of 0.1 % and higher, but had a protective effect on cells with incubation time of 5 min and concentrations up to 0.1 %. BBG at concentrations of 0.025 % protected against TB-induced damage at 5 min and 30 min incubation. Salt concentrations between 113 and 225 mM did not influence cell survival even after 30 min. In the presence of TB, propidium iodide bound strongly to the cells.

Conclusions

BBG acts as a protecting agent against TB toxicity.     

Comparisons of cone electroretinograms after indocyanine green-, brilliant blue G-, or triamcinolone acetonide-assisted macular hole surgery

Purpose

To compare the function of retinal ganglion cells (RGCs) using the photopic negative response (PhNR) in patients who had undergone indocyaine green (ICG)-assisted, brilliant blue G (BBG)-assisted, or triamcinolone acetonide (TA)-assisted internal limiting membrane (ILM) peeling during macular hole (MH) surgery.

Methods

Forty-eight eyes of 48 patients with a macular hole were randomly divided into those undergoing ICG-assisted, BBG-assisted, or TA-assisted vitrectomy (n?=?16 for each group). Full-field cone ERGs were recorded before and 1, 3, 6, 9, and 12 months postoperatively. The amplitudes and implicit times of the a-waves and b-waves and the amplitudes of the oscillatory potentials (OPs) and PhNRs were measured. The mean deviations (MDs) of standard automated perimetry and the best-corrected visual acuity (BCVA) were measured. The circumferential retinal nerve fiber layer (RNFL) thickness was evaluated by SD-OCT.

Results

All macular holes were closed with a significant improvement of the BCVA and MD without differences among the groups. There was no significant difference between the preoperative and postoperative RNFL thickness. The implicit times of the a-waves and b-waves were significantly prolonged, and the ΣOPs amplitude was significantly decreased postoperatively in all groups. These ERG changes were not significantly different among the groups. The postoperative PhNR amplitudes were significantly lower in the ICG group than in the BBG or TA group.

Conclusions

The results indicate that the PhNR may detect subclinical impairments of RGCs caused by the possible toxic effect of ICG. This finding adds to the data that BBG and TA may be safer than ICG for use during MH surgery.     

Complication rate and risk factors for intraoperative complications in resident-performed phacoemulsification surgery

Background/Aim

To determine the complication rate and risk factors for intraoperative complications in resident-performed phacoemulsification surgery at a tertiary care center during the first 100 surgeries.

Methods

Retrospective chart review of the first 100 performed phacoemulsification cases of six consecutive residents. Posterior capsule tear, vitreous loss, and dislocation of lenticular fragments into the vitreous were defined as intraoperative complications. Patient characteristics considered risk factors for surgery were identified and correlated with the occurrence of intraoperative complications.

Results

Complications occurred in 23 of 600 operations (3.8?%). Surgery was complicated by posterior capsular tear in 23 eyes (3.8?%) with vitreous loss in 17 eyes (2.8?%) and loss of lenticular fragments into the vitreous in seven eyes (1.2?%). Eyes with dense nuclear sclerosis (p?=?0.002) and white cataracts (p?=?0.019) were associated with a statistically significantly greater incidence of posterior capsular tears and vitreous loss (p?=?0.007 and p?=?0.027 respectively). An intraocular lens was implanted in 591 eyes as intended.

Conclusions

Residents achieve an acceptable complication rate during their initial 100 phacoemulsification cases.     

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

Background

Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties.

Methods

A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3–6 (aged 9–11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n?=?46) and a without-treatment group (n?=?36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed.

Results

Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p?=?0.01).

Conclusion

No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.     

Intraoperative iatrogenic peripheral retinal break in 23-gauge transconjunctival sutureless vitrectomy versus 20-gauge conventional vitrectomy

Background

To compare the incidence of intraoperative iatrogenic peripheral retinal breaks (IPRBs) during 23-gauge transconjunctival sutureless vitrectomy (TSV) and conventional 20-gauge vitrectomy for various indications.

Methods

This was a single-center, comparative, retrospective, interventional case series of 973 23-gauge TSVs and 402 conventional 20-gauge vitrectomies done by two surgeons between January 2004 and December 2009. The incidence rate of intraoperative IPRBs and risk factors were analyzed in association with various clinical and surgical factors.

Results

IPRBs occurred significantly less often during 23-gauge TSV (16 of 973 cases, 1.6 %) than during conventional vitrectomy (25 of 402 cases, 6.2 %, P?<?0.001). Univariate analysis revealed that conventional vitrectomy and operation time were risk factors for the complication. Multivariate logistic regression analysis also revealed that conventional vitrectomy (P?=?0.03, OR?=?2.91), operation time (P?<?0.01, OR?=?1.01), and intraoperative induction of posterior vitreous detachment (PVD, P?=?0.04, OR?=?1.97) were risk factors for IPRBs.

Conclusions

The 23-gauge TSV procedure with the trocar system has a lower incidence of intraoperative IPRBs than conventional 20-gauge vitrectomy. Longer operation time and induction of PVD are also independent risk factors of the complication.     

Comparison of UVA- and UVA/riboflavin-induced growth inhibition of Acanthamoeba Castellanii

Purpose

To investigate whether ultraviolet light (UVA) at 365 nm can inhibit/eliminate Acanthamoeba growth and if riboflavin would potentiate such an association.

Methods

Acanthamoeba castellanii in a fluid medium with a concentration of approximately 1.7?×?10⁴ protozoa/ml were prepared with (0.01 %) and without riboflavin. Exposure of UVA (dose 5.475 J/cm²) took place twice, with each illumination period followed by culturing of 10 μl in peptone yeast-extract glucose (PYG) medium for 7 days. Every suspension prepared had a non-exposed control solution. Determination of Acanthamoeba was conducted daily, by count in Burker chamber days 4 through 7 after exposure. Statistical analysis was done by repeated-measurement ANOVA and post-hoc analysis for unpaired samples.

Results

The exposure of ultraviolet light resulted in an inhibited growth of Acanthamoeba compared to the non-exposed solutions, with a statistically significant reduction over time (p?=?0.0003). The addition of riboflavin did not amplify the effect, and there were no tendencies for an interaction effect between UVA and riboflavin.

Conclusions

The antiprotozoal effect of the UVA wavelength, utilized in CXL, is solely mediated by ultraviolet light, and riboflavin does not seem to amplify the antimicrobial efficacy.     

Light–dark changes in iris thickness and anterior chamber angle width in eyes with occludable angles

Backgound

The purpose of this study was to investigate and measure light–dark changes in iris thickness (IT) and anterior chamber angle width in eyes with occludable angles and open angles by using anterior segment optical coherence tomography (AS-OCT).

Methods

We examined 153 eyes of 153 Japanese patients with primary angle closure suspect, primary angle closure, primary angle closure glaucoma, or primary open angle glaucoma. AS-OCT was used to determine pupil diameter, IT, angle opening distance at 500 μm (AOD₅₀₀), and trabecular-iris space area at 500 μm (TISA₅₀₀) in each quadrant of the anterior chamber angle (superior, inferior, temporal, and nasal) under light and dark conditions.

Results

In the angle closure cases, IT, AOD₅₀₀ and TISA₅₀₀ in the dark varied significantly among the four quadrants (P?<?0.05, analysis of variance). In contrast, in the open angle cases, IT, AOD₅₀₀ and TISA₅₀₀ in the dark did not differ significantly among the four quadrants. In the angle closure cases and the open angle cases, significant negative associations were found between IT difference [IT_(light)–IT_(dark)] and AOD₅₀₀ difference [AOD_500(light)–AOD_500(dark)] (R?=??0.411, P?<?0.001 and R?=??0.501, P?=?0.001, respectively) and between IT difference and TISA₅₀₀ difference [TISA_500(light)–TISA_500(dark)] (R?=??0.475, P?<?0.001 and R?=??0.462, P?=?0.002, respectively).

Conclusion

Our results suggest that thickening of the iris root under dark conditions is related to the mechanism of primary angle closure. It is important to analyze both the angle structure and peripheral IT in each quadrant.     

A modified Hartmann–Shack aberrometer for measuring stray light in the anterior segment of the human eye

Purpose

To examine the use of a modified Hartmann–Shack wave front aberrometer (WASCA; Carl Zeiss Meditec AG, Germany) to measure objective stray light caused by forward light scatter from the anterior segment of the human eye.

Setting

HELIOS Klinikum Erfurt/Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Germany.

Method

Scatter parameters, including the Michelson contrast and cross-sectional area at half height (CAHM) were examined in Hartmann–Shack images from ten subjects with a cataract in one eye and an intraocular lens (IOL) in the other. The parameters were compared between each eye. Light scatter was then measured in 40 healthy subjects (age range, 23–75 years) with spherical ametropia ranging from ?0.25 to 0.25 diopters. The subjects were divided into three age groups; 23–35, 36–50, and 51–75 years. Light scatter was also measured using four alternative methods.

Results

CAHM and contrast were significantly different between the eyes with the cataract and the IOL (P?=?0.007 and P?=?0.004, respectively). CAHM (r?=?0.557, P?<?0.001) and contrast (r?=??0.467, P?<?0.001) were both significantly correlated with age. There were significant differences in CAHM and contrast between the age groups.

Conclusion

The modified wave front aberrometer can be used to measure stray light, although its diagnostic sensitivity in individual patients must be improved.     

Perfluorocarbon liquid-assisted membrane staining and peeling technique for macular diseases

Purpose

A surgical technique is described that facilitates membrane peeling in patients with macular diseases by using small amounts of perfluorocarbon liquid (PFCL) and brilliant blue G (BBG) dye.

Study Design

Retrospective cohort study.

Methods

After placing about 1.0-1.5 cc PFCL on the macular area, BBG was applied with a 27-gauge blunt needle at the interface of PFCL and retina. The membrane peeling was performed under PFCL.

Results

The amount of BBG dye with PFCL-assisted staining technique has the potential to be smaller than in conventional staining method. Since the displacement angle of the membrane during peeling procedures is considerably increased by PFCL, combined with its high specific gravity and interfacial tension, the risk of tearing the membrane during manipulation is reduced to a great extent. The postoperative visual function in patients with PFCL-assisted peeling was comparable to that of patients without PFCL-assisted peeling.

Conclusion

The PFCL-assisted technique enables sufficient membrane staining with minimal amounts of BBG dye, with tearing of the epiretinal membrane or internal limiting membrane being less likely than with the conventional method.

     

Retinal neurovascular coupling in patients with glaucoma and ocular hypertension and its association with the level of glaucomatous damage

Purpose

To analyze neurovascular coupling in the retina of untreated primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients.

Patients and methods

Maximal vessel dilation in response to flicker light was analyzed with Retinal Vessel Analyzer (RVA) in temporal superior/inferior arterioles and veins in 51 POAG patients, 46 OHT and 59 control subjects. RVA parameters were compared between groups, between contralateral POAG eyes, and correlated to intraocular pressure, visual field mean defect and retinal nerve fiber layer thickness.

Results

POAG eyes demonstrated generally smaller response of all vessels to flicker light than the other two groups (ANOVA p?=?0.026; mean arterial flicker response in percent of baseline, averaged superior and inferior was 3.48?±?2.22 % for controls , 2.35?±?2.06 % for POAG patients , and 2.97?±?2.35 % for OHT patients; corresponding values for venules were 3.88?±?1.98 %, 2.89?±?1.72 %, 3.45?±?2.77 %). There was no difference in flicker response between the eye with more and less advanced damage in each patient of the POAG group (ANOVA p?=?0.79). Correlation of flicker response to intraocular pressure (IOP) was borderline at best, correlations to the level of glaucomatous damage were not significant. Correlation of flicker response of superior and inferior vessels of the same eye was significant for the arteries (Pearson r?=?0.23, p?=?0.004), as well as venules (r?=?0.52, p?<?0.001).

Conclusion

General vessel response to flicker light was decreased in POAG patients, compared to normal controls and OHT patients. In contrast to significant correlation between the two contralateral eyes of the flicker response itself, only its borderline correlation to IOP was seen. There was no correlation to the level of damage, altogether indicating a systemic dysregulation phenomenon.

Grants

Swiss National Foundation Grant 3200B0-113685, Velux Stiftung Grant, Freie Akademische Gesellschaft (FAG) Grant, Pfizer Inc. Grant

Clinical trial registration reference number

ClinicalTrials.gov NCT00430209     

Spontaneous eyeblink activity under different conditions of gaze (eye position) and visual glare

Purpose

To further evaluate the spontaneous eyeblink rate (SEBR) of healthy adult human subjects according to direction of gaze, especially in the presence of bright light reflective glare.

Methods

On 32 subjects aged between 18 and 24 years, separate video recordings of 5 min duration were made with different conditions of gaze (horizontal, slightly upwards or slightly downwards) under normal lighting or a distant lighting glare source.

Results

The SEBR in primary eye gaze under normal lighting was 11.7 +/? 0.9 eyeblinks/min with a coefficient of variation (COV) of 20.5 %. A non-significant decrease in SEBR was noted with downward gaze, but a slight significant increase with upward gaze in both SEBR (to 13.0 +/? 1.1 eyeblinks/min) and COV (average 26.1 %). In the presence of glare, SEBR in primary eye gaze increased significantly (p?<?0.001) to 14.4 +/? 1.3 eyeblinks/min, with an obvious time-related progressive increase (p?<?0.001). On upward gaze in the presence of a glare stimulus, SEBR progressively increased even further (average 15.0 +/? 2.4 eyeblinks/min; p?<?0.001), as did the COV (to 29.2 %).

Conclusions

The results indicate that spontaneous eyeblink activity in silence can be affected by the presence of a glare light source, especially if the subjects are looking slightly upwards. This scenario should be avoided, if at all possible, in assessments of spontaneous eyeblink activity.     

Photophobia measurement in intermittent exotropia using the contrast sensitivity test

Background

To assess the presence and extent of photophobia in children with intermittent exotropia (X[T]) using the contrast sensitivity test.

Methods

Fifty-eight children with X(T) and 34 normal controls were studied with the functional acuity contrast test. Each participant viewed the stimuli of contrast monocularly and binocularly under photopic and mesopic conditions, performed with and without glare. Photophobia was defined as a reduction of contrast sensitivity caused by glare light. We compared the photophobia of children with X(T) to that of normal controls, and to the photophobia 3 months after muscle surgery.

Results

With stimuli of glare, the contrast sensitivity of children with X(T) was suppressed at intermediate spatial frequencies under mesopic condition (p?=?0.006 for 6 cycles per degree [cpd], p?=?0.027 for 12 cpd), whereas that of normal controls showed no difference. It occurred when X(T) patients viewed targets binocularly, and significantly improved after strabismus surgery (p?=?0.003 at 6 cpd). The measured photophobia of X(T) was strongly correlated to the photophobia symptoms reported by parents (p?=?0.002).

Conclusions

The mesopic contrast sensitivity with glare can represent the photophobia of children with X(T). Contrast sensitivity may be a useful measure for monitoring symptoms related to X(T).     

The effect of pre-adapting light intensity on dark adaptation in early age-related macular degeneration

Background

This study aimed to identify the pre-adapting light intensity that generated the maximum separation in the parameters of dark adaptation between participants with early age-related macular degeneration (AMD) and healthy control participants in the minimum recording time.

Methods

Cone dark adaptation was monitored in 10 participants with early AMD and 10 age-matched controls after exposure to three pre-adapting light intensities, using an achromatic annulus (12° radius) centred on the fovea. Threshold recovery data were modelled, and the time constant of cone recovery (τ), final cone threshold, and time to rod-cone-break (RCB) were determined. The diagnostic potential of these parameters at all pre-adapting intensities was evaluated by constructing receiver operating characteristic (ROC) curves.

Results

There were significant differences between those with early AMD and healthy controls in cone τ and time to RCB (p < 0.05) at all pre-adapting ‘bleaching’ intensities. ROC curves showed that the diagnostic potential of dark adaptometry was high following exposure to all three pre-adapting intensities, generating an area under the curve in excess of 0.87 ± 0.08 for cone τ and time to RCB for all conditions.

Conclusions

Dark adaptation was shown to be highly diagnostic for early AMD across a range of pre-adapting light intensities, and therefore, the lower pre-adapting intensities evaluated in this study may be used to expedite dark adaptation measurement in the clinic without compromising the integrity of the data obtained. This study reinforces the suggestion that cone and rod dark adaptation are good candidate biomarkers for early AMD.     

Management of delayed suprachoriodal haemorrhage after intraocular surgery and trauma

Backgroud

To indentify surgical risk factors for delayed suprachoroidal haemorrhage (DSCH) and to report the outcomes of an effective intervention in a consecutive of patients.

Methods

The clinical data of ten patients diagnosed with DSCH in our hospital between July 2007 and December 2012 were extracted from hospital records and analyzed, including ophthalmologic examination, ophthalmologic ultrasonography, surgical procedures, and outcome measures including visual acuity and intraocular pressure.

Results

Ten eyes of ten patients including six men and four women with mean age of 56.6?±?17.67 years, with DSCH, were enrolled. After diagnosis, drainage or/and pars plana vitrectomy were performed for eight patients; another two received conservative treatment. All the patients were followed up for 15.2?±?4.3 months. Intraocular pressure decreased significantly (p?<?0.001); the mean final visual acuity improved significantly after intervention (p?<?0.001).

Conclusions

We emphasized other great risk factors such as intraoperative mitomycin-C use, systemic anticoagulation or thrombolysis, and chronic kidney disease. It seems that earlier surgical intervention after the diagnosis of DSCH will be beneficial to patients by improving their final visual acuity.     

Assessment of fungal viability after long-wave ultraviolet light irradiation combined with riboflavin administration

Background

Corneal collagen cross-linking (CXL), a technique that combines riboflavin administration with long-wave ultraviolet light irradiation, was primarily developed to increase the biomechanical strength of collagen fibrils of the cornea to avoid the progression of keratoconus. Recently, this method has been proposed to treat selected cases of infectious keratitis.

Methods

To test the protocol used for progressive keratoconus in infectious keratitis, Candida albicans, and Fusarium solani, strains were exposed to irradiation using a wavelength of 365 nm at a power density of 3 mW/cm² for 30 min in the presence of riboflavin photosensitizer. All experiments were performed in triplicate. Qualitative and quantitative measurements of fungal viability used plate cultures and an automated trypan blue dye exclusion method respectively. Fungal cell diameter was also assessed in all groups. Statistical analyses were performed using the triplicate values of each experimental condition.

Results

Experimental findings of photodynamic therapy applied to the cell inactivation of both yeasts and filamentous fungi were compared with control groups. Qualitative results were corroborated with quantitative findings which showed no statistical significance between challenged samples (experimental groups) and the control group (p-value?=?1). In comparison with a control group of live cells, statistical significance was observed when riboflavin solution alone had an effect on the morphologic size of filamentous fungi, while ultraviolet light irradiation alone showed a slight decrease in the cell structure of C. albicans.

Conclusions

The impact of long-wave ultraviolet combined with riboflavin photosensitizer showed no antifungal effect on C. albicans and F. solani. The significant decrease in cell morphology of both filamentous fungi and yeasts submitted to photosensitizing riboflavin and exposure to ultraviolet light, respectively, may be promising in the development and standardization of alternatives for fungal cell inactivation, because of their minimal cytotoxic effects on the corneal surface. The methodological improvement in the preparation and application of individual chemical compounds, such as riboflavin, or physical systems, such as a long-wave light source, as antifungal agents may also assist in establishing promising therapeutic procedures for keratomycosis.     

Comparison of cathode ray tube and liquid crystal display stimulators for use in multifocal VEP

Purpose

To compare the modified signal-to-noise ratio (SNR*) of multifocal visual evoked potential (mfVEP) responses elicited by a cathode ray tube (CRT) and liquid crystal display (LCD) monitor in normal subjects.

Methods

An LCD monitor and CRT monitor were luminance and contrast matched. Luminance stability and the effect of viewing angle on luminance and contrast was measured for both screens. The SNR* of mfVEP responses from 15 normal subjects was compared between the stimulators using repeated measures analysis of variance.

Results

The CRT monitor took 10 min from switch on to reach the desired luminance compared to 60 min for the LCD monitor. LCD luminance was sensitive to variations in ambient temperature, fluctuating by 10 cd/m^?2 over approximately 20–27 °C, whereas CRT luminance was stable. Luminance variation from the centre to the edge of the CRT screen was 8 % when viewed perpendicularly and 28 % when viewed at an angle of 25°, compared to 24 and 46 %, respectively, for the LCD screen. Contrast was >94 % and varied by <3 % across both monitors for both viewing conditions. There was no significant difference in SNR* between responses elicited by the two stimulators (p = 0.76).

Conclusions

CRT and LCD stimulators elicited mfVEP responses with similar SNR* in normal subjects. This study highlighted practical issues with the use of LCD monitors as visual stimulators, particularly with regard to warm-up time, luminance stability and luminance uniformity.