Vincenzo Parisi

Correlation between optical coherence tomography, pattern electroretinogram, and visual evoked potentials in open-angle glaucoma patients

OBJECTIVE [corrected] To correlate the nerve fiber layer (NFL) thickness and the visual function evaluated by electrophysiologic retinal and cortical responses assessed in open-angle glaucoma (OAG) eyes. DESIGN Prospective case-control study. PARTICIPANTS Thirty glaucoma patients (mean age, 47.1 +/- 7.15 years; refractive error range, +/- 2 spherical equivalent) with a mean deviation of computerized static perimetry (24/2 Humphrey, Dublin, CA) from -5 to -28 dB and intraocular pressure less than 21 mmHg on pharmacologic treatment and 14 age-matched control participants. METHODS Nerve fiber layer thickness was measured by optical coherence tomography. Retinal and visual pathway function was assessed by simultaneously recording pattern electroretinograms (PERGs) and visual evoked potentials (VEPs) using high-contrast (80%) checkerboard stimuli (the single check edges subtend 15 minutes of the visual arc) reversed at the rate of two reversals per second. Linear regression analyses were adopted to establish the correlation between NFL thickness and PERG and VEP parameters. MAIN OUTCOME MEASURES Nerve fiber layer thickness measurements in each quadrant (superior, inferior, nasal, and temporal) were taken and then averaged (12 values averaged) and identified as NFL overall, whereas the data obtained in the temporal quadrant only (three values averaged) were identified as NFL temporal. PERG P50 implicit time and P50-N95 amplitude and VEP P100 implicit time and N75-P100 amplitude were also measured. RESULTS In OAG eyes, we found a significant (P < 0.01) reduction in NFL thickness in both NFL overall and NFL temporal evaluations with respect to the values observed in control eyes. PERG and VEP parameters showed a significant (P < 0.01) delay in implicit time and a reduction in peak-to-peak amplitude. In OAG eyes, the NFL overall and NFL temporal values were significantly correlated (P < 0.01) with the PERG P50 implicit time and P50-95 peak-to-peak amplitude. No correlations (P > 0.01) between NFL values and VEP parameters were found. CONCLUSIONS There is a correlation between PERG changes and NFL thickness, but there is no correlation between VEP changes and NFL thickness in patients affected by OAG.

The influence of axial length on retinal nerve fibre layer thickness and optic-disc size measurements by spectral-domain OCT

Background To evaluate the influence of axial length on measurements of the retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters in healthy subjects. Methods Using Cirrus HD-OCT, RNFL thickness and ONH parameters (disc and rim area) were measured in 15 short (<22.5 mm), 15 medium (22.51–25.5 mm) and 15 long (>25.51 mm) eyes. Results The mean axial length was 21.5±0.5 mm in short eyes, 24.1±0.8 mm in medium eyes and 26.6±1.0 mm in long eyes. The RNFL thickness decreased with longer axial lengths in the superior (r=−0.52, r2=0.27, p=0.0003), inferior (r=−0.72, r2=0.52, p<0.0001), nasal (r=−0.60, r2=0.37, p<0.0001) and temporal (r=−0.30, r2=0.09, p=0.0485) quadrants, as well as in the 360° mean measurement (r=−0.69, r2=0.48, p<0.0001). The optic-disc area (r=−0.74, r2=0.54, p<0.0001) and rim area (r=−0.41, r2=0.17, p=0.0051) decreased with longer axial lengths. Correcting for axial length-induced ocular magnification by means of the Littmann formula resolved the relationship between axial length and both RNFL thickness and ONH area. Discussion Axial length influences measurements of RNFL thickness and ONH parameters in healthy subjects. Caution is recommended when comparing the measured values of myopic and hyperopic eyes with the normative database of the instrument.

Evaluation of primary surgical procedures for retinal detachment with macular hole in highly myopic eyes: A randomized comparison of vitrectomy versus posterior episcleral buckling surgery

PURPOSE To evaluate postoperative outcomes between pars plana vitrectomy (PPV) and posterior episcleral buckle procedure (PEBP) in myopic eyes with retinal detachment (RD) and macular hole (MH). DESIGN Retrospective nonrandomized comparative interventional trial. PARTICIPANTS AND INTERVENTION The study included 30 phakic, highly myopic eyes (from 19-30 negative diopters) of 30 patients with an RD and MH. The patients were divided into two groups: They were assigned to PPV (15 eyes, group A) or to PEBP (15 eyes, group B). No significant (P > 0.01) differences in preoperative visual acuity (VA) between group A and group B eyes were found. Follow-up was 12 months. MAIN OUTCOME MEASURES Anatomic attachment of the retina was determined, and VA was measured. RESULTS Retinal reattachment was obtained on 11 of 15 (73.3%) eyes of group A and on 14 of 15 (93.3%) eyes of group B. In group A eyes the VA was substantially unmodified after surgical treatment, whereas in group B eyes the VA observed after surgical treatment increased significantly (P < 0.001) with respect to the preoperative values. CONCLUSIONS PEBP resulted in better postoperative anatomic and functional results compared with PPV in eyes with extreme degrees of myopia, pronounced posterior staphyloma, and posterior vitreous schisis affected with RD caused by MH.

Retinal nerve fiber layer thickness changes in Parkinson disease: a meta-analysis.

Background Parkinson disease (PD) is a neurodegenerative process that leads to a selective loss of dopaminergic neurons, mainly in the basal ganglia of the brain. Numerous studies have analyzed the ability of optical coherence tomography (OCT) to detect retinal nerve fiber layer (RNFL) thickness abnormalities and changes in PD, but the results have not always been consistent. Therefore, we carried out a meta-analysis to evaluate the RNFL thickness measured with OCT in PD. Methods and Findings Case-control studies were selected through an electronic search of the Cochrane Controlled Trials Register, PUBMED and EMBASE. For the continuous outcomes, we calculated the weighted mean difference (WMD) and 95% confidence interval (CI). The statistical analysis was performed by RevMan 5.0 software. Thirteen case-control studies were included in the present meta-analysis, containing a total of 644 eyes in PD patients and 604 eyes in healthy controls. The results of our study showed that there was a significant reduction in average RNFL thickness in patients with PD compared to healthy controls (WMD = −5.76, 95% CI: −8.99 to −2.53, P = 0.0005). Additionally, differences of RNFL thickness in superior quadrant (WMD = −4.44, 95% CI: −6.93 to −1.94, P = 0.0005), inferior quadrant (WMD = −7.56, 95% CI: −11.33 to −3.78, P<0.0001), nasal quadrant (WMD = −3.12, 95% CI: −5.63 to −0.61, P = 0.01) and temporal quadrant (WMD = −4.63, 95% CI: −7.20 to −2.06, P = 0.0004) were all significant between the two groups. Conclusion In view of these results and the noninvasive nature of OCT technology, we surmise that OCT could be a useful tool for evaluating the progression of the Parkinson disease. Trial Registration ClinicalTrials.gov NCT01928212

Cataract surgery as a risk factor for retinal detachment in very highly myopic eyes

PURPOSE To evaluate the incidence of retinal detachment (RD) after cataract surgery performed by phacoemulsification in very highly myopic eyes. DESIGN Retrospective, paired-eye, case-control trial. PARTICIPANTS AND INTERVENTION We assessed the development of RD in 930 eyes from 930 subjects (mean age = 62.5 +/- 8.5 years) affected by very high myopia (between -15 and -30 diopters) undergoing cataract surgery after uncomplicated phacoemulsification (cataract-subjected [CS] eyes). Fellow eyes served as controls. Follow-up was 36 months. MAIN OUTCOME MEASURE Detachment of the retina. RESULTS Retinal detachment was observed in 8.0% of CS eyes compared with 1.2% of control eyes (P<0.01, chi-square test). In CS eyes, posterior RD was most common (52.7% of eyes with RD). In control eyes, peripheral detachments with or without macular involvement were most common (47.3% of eyes with RD). CONCLUSION Cataract surgery, despite the use of a safe technique such as phacoemulsification, increases the risk of RD development in very highly myopic eyes.

Abnormal cortical responses to somatosensory stimulation in medication-overuse headache

BackgroundMedication-overuse headache (MOH) is a frequent, disabling disorder. Despite a controversial pathophysiology convincing evidence attributes a pivotal role to central sensitization. Most patients with MOH initially have episodic migraine without aura (MOA) characterized interictally by an absent amplitude decrease in cortical evoked potentials to repetitive stimuli (habituation deficit), despite a normal initial amplitude (lack of sensitization). Whether central sensitization alters this electrophysiological profile is unknown. We therefore sought differences in somatosensory evoked potential (SEP) sensitization and habituation in patients with MOH and episodic MOA.MethodsWe recorded median-nerve SEPs (3 blocks of 100 sweeps) in 29 patients with MOH, 64 with MOA and 42 controls. Episodic migraineurs were studied during and between attacks. We measured N20-P25 amplitudes from 3 blocks of 100 sweeps, and assessed sensitization from block 1 amplitude, and habituation from amplitude changes between the 3 sequential blocks.ResultsIn episodic migraineurs, interictal SEP amplitudes were normal in block 1, but thereafter failed to habituate. Ictal SEP amplitudes increased in block 1, then habituated normally. Patients with MOH had larger-amplitude block 1 SEPs than controls, and also lacked SEP habituation. SEP amplitudes were smaller in triptan overusers than in patients overusing nonsteroidal anti-inflammatory drugs (NSAIDs) or both medications combined, lowest in patients with the longest migraine history, and highest in those with the longest-lasting headache chronification.ConclusionsIn patients with MOH, especially those overusing NSAIDs, the somatosensory cortex becomes increasingly sensitized. Sensory sensitization might add to the behavioral sensitization that favors compulsive drug intake, and may reflect drug-induced changes in central serotoninergic transmission.

Macular function in eyes with early age-related macular degeneration with or without contralateral late age-related macular degeneration

Purpose: To evaluate psychophysical and electrophysiologic responses in eyes with early age-related macular degeneration (AMD) without a decrease in visual acuity and with or without late AMD in the fellow eye. Methods: Fifteen patients (mean age: 67.9 ± 7.20 years) with early AMD in both eyes (AMD1 group, 15 eyes) and 15 patients (mean age: 71.40 ± 7.06 years) with early AMD in one eye and late AMD in the fellow eye (AMD2 group, 15 eyes) were enrolled. They were compared to 15 age-similar normal control subjects. LogMAR visual acuity (VA), macular sensitivity by MP-1 microperimetry, and multifocal electroretinograms (mfERG) were assessed in control, AMD1, and AMD2 eyes. mfERG response amplitude density (RAD, nV/deg2) of the N1-P1 component of first order binary kernels was measured. Results: When compared to controls, AMD1 and AMD2 eyes showed a significant (analysis of variance, P < 0.01) decrease in MP-1 microperimetry assessed in the 0–2.5 and 2.5–5 degrees of the macula, significantly correlated (Pearson test, P < 0.01) to the corresponding significant decrease (P < 0.01) in mfERG N1-P1 RADs assessed in the 0–2.5 and 2.5–5 degrees. In AMD1 and AMD2 eyes, VA and mfERG N1-P1 RADs assessed in the 5–20 degrees were similar (P > 0.01) to controls. VA, MP-1, and mfERG values were not significantly different in AMD1 and AMD2 eyes. Conclusion: In eyes with early AMD there is a dysfunction of preganglionic elements in the central 0–5 retinal degrees detectable by mfERG or MP-1 microperimetry. This impairment is not further influenced by the presence of late AMD in the fellow eye.

Optical Coherence Tomography in Alzheimer’s Disease: A Meta-Analysis

Background Alzheimer’s disease (AD) is a neurodegenerative disorder, which is likely to start as mild cognitive impairment (MCI) several years before the its full-blown clinical manifestation. Optical coherence tomography (OCT) has been used to detect a loss in peripapillary retina nerve fiber layer (RNFL) and a reduction in macular thickness and volume of people affected by MCI or AD. Here, we performed an aggregate meta-analysis combining results from different studies. Methods and Findings Data sources were case-control studies published between January 2001 and August 2014 (identified through PubMed and Google Scholar databases) that examined the RNFL thickness by means of OCT in AD and MCI patients compared with cognitively healthy controls. Results 11 studies were identified, including 380 patients with AD, 68 with MCI and 293 healthy controls (HC). The studies suggest that the mean RNFL thickness is reduced in MCI (weighted mean differences in μm, WMD = -13.39, 95% CI: -17.34 to -9.45, p = 0.031) and, even more so, in AD (WMD = -15.95, 95% CI: -21.65 to -10.21, p<0.0001) patients compared to HC. RNFL in the 4 quadrants were all significantly thinner in AD superior (superior WMD = -24.0, 95% CI: -34.9 to -13.1, p<0.0001; inferior WMD = -20.8, 95% CI: -32.0 to -9.7, p<0.0001; nasal WMD = -14.7, 95% CI: -23.9 to -5.5, p<0.0001; and temporal WMD = -10.7, 95% CI: -19.9 to -1.4, p<0.0001); the same significant reduction in quadrant RNFL was observed in MCI patients compared with HC (Inferior WMD = -20.22, 95% CI: -30.41 to -10.03, p = 0.0001; nasal WMD = -7.4, 95% CI: -10.08 to -4.7, p = 0.0000; and temporal WMD = -6.88, 95% CI: -12.62 to -1.13, p = 0.01), with the exception of superior quadrant (WMD = -19.45, 95% CI: -40.23 to 1.32, p = 0.06). Conclusion Results from the meta-analysis support the important role of OCT for RNFL analysis in monitoring the progression of AD and in assessing the effectiveness of purported AD treatments.

Carotenoids in Age-related maculopathy Italian study (CARMIS): Two-year results of a randomized study

Purpose The high concentration of carotenoids in the macula, plus evidence linking oxidative stress to age-related macular degeneration (AMD) and carotenoids to antioxidation, generated the hypothesis that higher antioxidant intakes can prevent AMD. The aim of this study was to determine whether nutritional supplementation with a targeted nutritional supplement improves visual acuity and visual function in AMD. Methods In this multicenter, prospective open-label randomized study, 145 patients were randomly assigned to 2 different treatment groups. Interventions were lutein (10 mg), zeaxanthin (1 mg), astaxanthin (4 mg; AZYR SIFI, Catania, Italy), and antioxidants/vitamins supplementation formula or no dietary supplementation for 2 years. Primary outcome was mean changes in visual acuity (VA) at 12 and 24 months. Other measures included contrast sensitivity (CS) and National Eye Institute visual function questionnaire (NEI VFQ-25) scores at 12 and 24 months. Results Patients in the treated group showed stabilization of VA with significantly (p=0.003) better VA scores (81.4±7.2) compared to the nontreated group (76.8±8.9) at 24-month follow-up. An improvement in CS (p=0.001) and final mean NEI VFQ-25 composite scores at 12 and 24 months higher in treated group compared to nontreated group were also shown (p<0.001). Conclusions Patients treated with lutein/zeaxanthin and astaxanthin together with other nutrients were more likely to report clinically meaningful stabilization/improvements in VA, CS, and visual function through 24 months compared with nontreated subjects. Further studies are needed with more patients and for longer periods of time.

Lateral inhibition in visual cortex of migraine patients between attacks

BackgroundThe interictal deficit of habituation to repetitive visual stimuli in migraine patients could be due to deficient intracortical inhibition and/or to low cortical pre-activation levels. Which of these abnormalities contributes more to the habituation deficit cannot be determined with the common methods used to record transient visual responses.We investigated lateral inhibition in the visual cortex during the migraine cycle and in healthy subjects by using differential temporal modulations of radial windmill-dartboard (WD) or partial-windmill (PW) visual patterns.MethodsTransient (TR-VEP) and steady-state visual-evoked potentials (SS-VEP) were recorded in 65 migraine patients (21 without and 22 with aura between attacks; 22 patients during an attack) and in 21 healthy volunteers (HV). Three stimulations were used in each subject: classic checkerboard pattern (contrast-reversion 3.1Hz), WD and PW (contrast-reversion ~4Hz). For each randomly presented stimulation protocol, 600 sweeps were acquired and off-line partitioned in 6 blocks of 100. Fourier analysis allowed data to extract in SS-VEP the fundamental (1H) and the second harmonic (2H) components that reflect respectively short-(WD) and long- range lateral inhibition (attenuation of 2H in WD compared to PW).ResultsCompared to HV, migraineurs recorded interictally had significantly less habituation of the N1-P1 TR-VEP component over subsequent blocks and they tended to have a smaller 1st block amplitude. 1H amplitude in the 1st block of WD SS-VEP was significantly greater than in HV and habituated in successive blocks, contrasting with an amplitude increase in HV. Both the interictal TR-VEP and SS-VEP abnormalities normalized during an attack. There was no significant between group difference in the PW 2H amplitude and its attenuation. When data of HV and migraine patients were combined, the habituation slope of WD-VEP 1H was negatively correlated with that of TR-VEP N1-P1 and with number of days since the last migraine attack.ConclusionThese results are in favour of a migraine cycle-dependent imbalance between excitation and inhibition in the visual cortex. We hypothesize that an interictal hypoactivity of monaminergic pathways may cause a functional disconnection of the thalamus in migraine leading to an abnormal intracortical short-range lateral inhibition that could contribute to the habituation deficit observed during stimulus repetition.