Giovanni Montesano

Comparison of Compass and Humphrey perimeters in detecting glaucomatous defects

Purpose To compare the performance of Compass fundus automated perimetry (FAP) and Humphrey Field Analyzer (HFA) in glaucoma patients. Methods A total of 120 patients with glaucoma underwent 1 FAP and 1 HFA perimetric test over the central 24° on one eye. The chosen eye and sequence were randomized and only reliable examinations were considered for analysis. Mean deviation (MD), pattern standard deviation (PSD), visual field index (VFI), and the area of absolute scotoma were compared between perimeters. Glaucoma Staging System (GSS2) data were analyzed by means of k test. Results Mean sensitivity difference (FAP-HFA) was −1.0 ± 2.81 dB (p<0.001, 95% confidence interval [CI] −1.61, −0.60 dB), MD difference was +0.27 ± 2.84 dB (p = 0.36, 95% CI −5.30, 5.83 dB), PSD difference was +0.48 ± 1.95 dB (p = 0.0075, 95% CI −3.37, 4.33 dB), and VFI difference was +2.4% ± 8.4% (p = 0.003, 95% CI −14.0%, +18.8% dB). Weighted kappa for GSS2 was 0.87. Points with null sensitivities were 9.9 ± 10.2 with FAP and 8.2 ± 8.9 with HFA (difference: 1.7 ± 4.0 points, p = 0.013). Conclusions Mean sensitivity with FAP is 1 dB lower than HFA, a finding due to different threshold strategies. Differences of global indices for FAP and HFA are small, which makes the 2 perimeters equivalent in the clinical setting. However, FAP seems more severe in evaluating glaucomatous damage, with absolute scotoma areas larger than with HFA. We raise the hypothesis that such difference may be the result of the active compensation of eye movements available with FAP.

Structure|[ndash]|function relationship in early diabetic retinopathy: a spatial correlation analysis with OCT and microperimetry

PurposeTo study the correlation of the local ganglion cell layer—inner plexiform layer (GCL-IPL) thickness with corresponding retinal sensitivity as studied with microperimetry in patients with Type 2 diabetes and no signs of diabetic retinopathy.Patients and methodsWe analyzed 35 healthy subjects (68 eyes) and 26 Type 2 diabetic patients (48 eyes) with no signs of diabetic retinopathy. We tested best corrected visual acuity (BCVA), monocular and binocular constrast sensitivity (CS, Pelli – Robson chart) and retinal sensitivity with microperimetry, and acquired dense macular SD-OCT scans. We then studied the correlation between local GCL-IPL thickness and local sensitivity.ResultsMean BCVA was 1.09 (±1.03) decimals in diabetic subjects and 1.02 (±0.15) decimals in healthy subjects. Only binocular CS was significantly higher in healthy subjects (1.18±0.42 for healthy subjects, 1.62±0.63 for diabetic subjects). In both local and global analysis we observed higher GCL-IPL thickness and higher sensitivity in normal compared with diabetic subjects, but no difference reached significance (p<0.05). Using a mixed multivariate linear model, we found a significant correlation between retinal sensitivity and the correspondent GCL-IPL thickness in diabetic subjects (0.022±0.006 dB/μm, p=0.0007) but not in healthy subjects (−0.002±0.006 dB/μm, p=0.77).Conclusiondespite close similarities between the two groups, we found a significant difference in the structure–function relationship in diabetic subjects without diabetic retinopathy, suggesting that diabetes might act as an additional effect in the normal deterioration of the visual function related to the inner retina.

Optical Coherence Tomography Angiography in a Normal Iris.

BACKGROUND AND OBJECTIVE Optical coherence tomography angiography (OCTA) is a new imaging technique for examining the macular region in many retinal diseases. The aim of this study was to assess the applicability of OCTA to detect iris vascularization. PATIENTS AND METHODS The irises of 28 eyes of 14 patients were examined with AngioVue OCT (Optovue, Fremont, CA). The usual technique was modified using the AngioRetina mode, but with the anterior segment optical adaptor lens, and without autofocus, while making manual adjustments. OCTA scans were captured in both eyes, always by the same operator. The images were acquired in 3 × 3 and 6 × 6 volume cubes. Raw data were then exported and split using an external tool provided by Optovue to obtain three-dimensional (3-D) iris reconstruction. RESULTS In all eyes, OCTA showed the arterial system more superficially and the venous system more deeply in 3-D reconstruction. CONCLUSION This is the first report of a study of the vascularization and 3-D reconstruction of the normal iris with OCTA. The method detects iris vascular network and indirectly provides information on the retinal circulation in situations where this is not visible without injecting sodium fluorescein. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1138-1142.].

Optical Coherence Tomography Angiography of Iris Nevus: A Case Report.

Iris nevus is common: 6% of patients with suspected iris melanoma have lesions other than melanoma, and 36% of them are nevi. Iris nevus turns into melanoma in approximately 8% of cases at a mean of 15 years. This case report provides the first description of an iris tumor examined with iris optical coherence tomography angiography (OCTA) compared to iris fluorescein angiography (IFA). A 60-year-old man with a diagnosis of iris nevus in the left eye was referred to our department for IFA and iris OCTA. The iris vasculature in IFA was visible only in the early phases, but not clearly. OCTA, however, gave visualization of the vascular network and very precisely defined the vessels of the whole lesion, except for the pupillary portion, which was masked by superficial pigment accumulations. IFA and iris OCTA can add information about the vascular architecture compared to slit-lamp biomicroscopy, ultrasound biomicroscopy, and anterior-segment OCT. However, IFA is time-consuming and invasive and can – very occasionally – cause serious adverse reactions. In contrast, OCTA defines the texture of the iris vasculature better. In conclusion, OCTA is a new method, easy to execute, needing no dye injection, and provides useful information on the vascular network of iris lesions. It could therefore be helpful in the diagnosis and follow-up of these lesions.

Choroidal Thickness Analysis in Patients with Usher Syndrome Type 2 Using EDI OCT

To portray Usher Syndrome type 2, analyzing choroidal thickness and comparing data reported in published literature on RP and healthy subjects. Methods. 20 eyes of 10 patients with clinical signs and genetic diagnosis of Usher Syndrome type 2. Each patient underwent a complete ophthalmologic examination including Best Corrected Visual Acuity (BCVA), intraocular pressure (IOP), axial length (AL), automated visual field (VF), and EDI OCT. Both retinal and choroidal measures were measured. Statistical analysis was performed to correlate choroidal thickness with age, BCVA, IOP, AL, VF, and RT. Comparison with data about healthy people and nonsyndromic RP patients was performed. Results. Mean subfoveal choroidal thickness (SFCT) was 248.21 ± 79.88 microns. SFCT was statistically significant correlated with age (correlation coefficient −0.7248179, p < 0.01). No statistically significant correlation was found between SFCT and BCVA, IOP, AL, VF, and RT. SFCT was reduced if compared to healthy subjects (p < 0.01). No difference was found when compared to choroidal thickness from nonsyndromic RP patients (p = 0.2138). Conclusions. Our study demonstrated in vivo choroidal thickness reduction in patients with Usher Syndrome type 2. These data are important for the comprehension of mechanisms of disease and for the evaluation of therapeutic approaches.

The volume of peripapillary vessels within the retinal nerve fibre layer: an optical coherence tomography angiography study of normal subjects

Background/aims To investigate the contribution of vascular volume calculated by optical coherence tomography angiography (OCTA) to the measurement of peripapillary retinal nerve fibre layer (RNFL) thickness. Methods We used OCTA scans to build volumetric maps of the RNFL angiograms by thresholding the decorrelation images and summing the number of white pixels along the z-axis at each location. We used these maps to calculate the contribution of the vascular tissue to the RNFL thickness. Results We analysed 51 eyes from 36 subjects. The mean RNFL volume calculated on the peripapillary region was 0.607±0.045 mm3 and the mean vessel volume was 0.217±0.035 mm3, with a mean vessel/total RNFL ratio of 35.627%±3.942%. When evaluated in the peripapillary circular section, the total contribution of the vascular tissue to the global RNFL thickness was 29.071%±3.945%. The superior and inferior sectors showed the highest percentage of vascular tissue within the RNFL circular profile (31.369% and 34.788% respectively). Conclusions We found that the vascular contribution to the RNFL thickness is 29.07±3.945%. This is much higher than what has been reported from calculations made on the structural OCT alone (13% reported by Hood et al and 11.3%±1.6% for the Cirrus OCT and 11.8%±1.4% for the Spectralis OCT reported by Patel et al). We conclude that evaluation of the vascular tissue contribution to the RNFL thickness with OCTA might be useful when performing precise quantification of the neuronal tissue.

Effect of prophylactic timolol 0.1% gel on intraocular pressure after an intravitreal injection of ranibizumab: a randomized study.

Purpose The purpose of this study is to make a prospective evaluation of the effect of timolol 0.1% eye gel on short-term intraocular pressure (IOP) after an intravitreal injection (IVI) of ranibizumab. Participants and methods One hundred and fifty eyes of 150 IVI-naïve patients with macular edema caused by various pathological conditions (age-related macular degeneration, central or branch retinal vein occlusion, and diabetic retinopathy) were scheduled to undergo an IVI of ranibizumab (0.5 mg/0.05 cc). The patients were randomly divided into three groups: 50 were not treated with timolol before the IVI (group 1); 50 received an instillation of timolol 0.1% eye gel the evening before the IVI (group 2); and 50 received an instillation of timolol 0.1% eye gel 2 hours before the IVI (group 3). The incidence of clinically significant intraocular hypertensive spikes (>25 mmHg and >40 mmHg) was then assessed. Results Our findings showed that mean IOP at baseline was significantly higher than at both 5 and 60 minutes after IVI (P<0.01). Spikes of >25 mmHg were recorded at either time in 27 patients (54%) in group 1, 23 patients (44%) in group 2, and 24 patients (48%) in group 3. None of the between-group differences were significant. Spikes of >40 mmHg (which were only detected 5 minutes after IVI) were recorded in nine (18%), eight (16%), and one patient (2%) in groups 1, 2, and 3, respectively. The only significant difference was between the control and group 3 (P=0.012). Conclusion An increase in IOP after antivascular endothelial growth factor IVI is a frequent complication. The prophylactic use of timolol 0.1% gel effectively reduced the mean IOP when administered 2 hours before IVI and was also effective in preventing dangerous IOP spikes of >40 mmHg. It is therefore recommended before IVIs as a means of preventing emergency procedures and preserving the health of the optic nerve.

Compass fundus automated perimetry

Background: Compass (CenterVue, Padova, Italy) is a fundus automated perimeter which has been introduced in the clinical practice for glaucoma management in 2014. The aim of the article is to review Compass literature, comparing its performances against Humphrey Field Analyzer (Zeiss Humphrey Systems, Dublin, CA, USA). Results: Analyses on both normal and glaucoma subjects agree on the fact that Humphrey Field Analyzer and Compass are interchangeable, as the difference of their global indices is largely inferior than test -retest variability for Humphrey Field Analyzer. Compass also enables interesting opportunities for the assessment of morphology, and the integration between morphology and function on the same device. Conclusion: Visual field testing by standard automated perimetry is limited by a series of intrinsic factors related to the psychophysical nature of the examination; recent papers suggest that gaze tracking is closely related to visual field reliability. Compass, thanks to a retinal tracker and to the active dislocation of stimuli to compensate for eye movements, is able to provide visual fields unaffected by fixation instability. Also, the instrument is a true colour, confocal retinoscope and obtains high-quality 60° × 60° photos of the central retina and stereo-photos details of the optic nerve. Overlapping the image of the retina to field sensitivity may be useful in ascertaining the impact of comorbidities. In addition, the recent introduction of stereoscopic photography may be very useful for better clinical examination.

Features of the normal choriocapillaris with OCT-angiography: Density estimation and textural properties

The main objective of our work is to perform an in depth analysis of the structural features of normal choriocapillaris imaged with OCT Angiography. Specifically, we provide an optimal radius for a circular Region of Interest (ROI) to obtain a stable estimate of the subfoveal choriocapillaris density and characterize its textural properties using Markov Random Fields. On each binarized image of the choriocapillaris OCT Angiography we performed simulated measurements of the subfoveal choriocapillaris densities with circular Regions of Interest (ROIs) of different radii and with small random displacements from the center of the Foveal Avascular Zone (FAZ). We then calculated the variability of the density measure with different ROI radii. We then characterized the textural features of choriocapillaris binary images by estimating the parameters of an Ising model. For each image we calculated the Optimal Radius (OR) as the minimum ROI radius required to obtain a standard deviation in the simulation below 0.01. The density measured with the individual OR was 0.52 ± 0.07 (mean ± STD). Similar density values (0.51 ± 0.07) were obtained using a fixed ROI radius of 450 μm. The Ising model yielded two parameter estimates (β = 0.34 ± 0.03; γ = 0.003 ± 0.012; mean ± STD), characterizing pixel clustering and white pixel density respectively. Using the estimated parameters to synthetize new random textures via simulation we obtained a good reproduction of the original choriocapillaris structural features and density. In conclusion, we developed an extensive characterization of the normal subfoveal choriocapillaris that might be used for flow analysis and applied to the investigation pathological alterations.

Functional mapping of brain synapses by the enriching activity-marker SynaptoZip

Ideally, elucidating the role of specific brain circuits in animal behavior would require the ability to measure activity at all involved synapses, possibly with unrestricted field of view, thus even at those boutons deeply located into the brain. Here, we introduce and validate an efficient scheme reporting synaptic vesicle cycling in vivo. This is based on SynaptoZip, a genetically encoded molecule deploying in the vesicular lumen a bait moiety designed to capture upon exocytosis a labeled alien peptide, Synbond. The resulting signal is cumulative and stores the number of cycling events occurring at individual synapses. Since this functional signal is enduring and measurable both online and ex post, SynaptoZip provides a unique method for the analysis of the history of synaptic activity in regions several millimeters below the brain surface. We show its broad applicability by reporting stimulus-evoked and spontaneous circuit activity in wide cortical fields, in anesthetized and freely moving animals.Visualization of synaptic activity in the living brain is challenging. This study devises a simple and efficient scheme that reports synaptic vesicle recycling in vivo using SynaptoZip, a genetically encoded sensor of past synaptic activities.