New insights into amiodarone induced retinal and optic nerve toxicity: functional and structural changes.

Background: Amiodarone is widely used for heart arrhytmia. Previous studies have suggested the possibility of optic neuropathy with the chronic use of this drug. Objectives: To identify structural or functional changes in the retina and optic nerve in patients on chronic amiodarone therapy without visual complaints. Methods: This observational study included 15 eyes of 15 patients with cardiac arrythmia on chronic amiodarone treatment and 15 healthy matched subjects as a control group. All subjects underwent electrophysiological tests [pattern visual evoked potential (PVEP), pattern electroretinogram (PERG), multifocal electroretinogram (mfERG), and optical coherence tomography (OCT) and angiography (OCTA)]. Results: There were no statistically significant differences between the two groups regarding the PVEP, PERG, and the mfERG parameters. Macular and optic nerve head OCT and OCTA have not shown statistically significant differences except for the morphological parameters of the optic disc (p = 0.008 for the horizontal and p = 0.013 for vertical cup/disc ratio and p = 0.045 for rim area). Conclusion: Patients on chronic amiodarone therapy have not shown evident structural or functional changes in the retinal or optic nerve as demonstrated by electrophysiological tests, OCT, and OCTA results compared to controls.

Optical coherence tomography and electrophysiological analysis of proptotic eyes due to thyroid-associated ophthalmopathy.

PURPOSE: To study the degree of morphological and functional changes in thyroid-associated ophthalmology (TAO) patients using optical coherence tomography and electrophysiological studies and investigate their clinical correlation. METHODS: A cross-sectional study including 40 patients with TAO and a control group with age- and sex-matched healthy subjects. All subjects underwent a complete ophthalmological examination, proptosis evaluation, spectral domain optical coherence tomography, and electrophysiological tests (pattern and multifocal electroretinograms, and visual evoked potentials). RESULTS: On multiple regression analysis, the degree of proptosis and P50 amplitude were the most important predictors of central foveal thickness (CFT) (ß = - 0.56 and 0.39 and p = 0.03 and 0.01, respectively); while duration of the disease, and clinical activity score (CAS) were the most important predictors of average RNFL thickness (ß = 0.67 and - 0.81 and p = 0.004 and < 0.001, respectively). CONCLUSION: In the absence of fundus changes, macular thinning along with functional alterations noticed by pattern and multifocal electroretinogram could indicate presence of subclinical retinopathy in TAO cases.

Correlation Between Optical Coherence Tomography and Photopic Negative Response of Flash Electroretinography in Ganglion Cell Complex Assessment in Glaucoma Patients.

Purpose: To investigate the correlation between the photopic negative response (PhNR) of the light-adapted flash electroretinography (ERG) and measurements of standard automated perimetry (SAP) and optical coherence tomography (OCT) in assessment of retinal ganglion cells' (RGCs) affection in glaucoma. Patients and Methods: A cross-sectional study included 40 eyes of glaucoma patients and 40 eyes of age- and gender-matched normal subjects. Participants underwent a complete ophthalmologic assessment, SAP, OCT, and light-adapted flash ERG using the extended PhNR protocol of the International Society for Clinical Electrophysiology of Vision (ISCEV). Glaucomatous eyes were divided into 3 subgroups: mild (n = 15), moderate (n = 11) and severe glaucoma (n = 14) according to the mean deviation (MD) of SAP. Measurements of SAP, OCT and ERG parameters were analyzed, and correlations between PhNR measurements and other study measurements were evaluated. Results: PhNR amplitudes and PhNR/b-wave ratios were significantly reduced in glaucoma cases compared to healthy controls, and they showed a significant and progressive decline across the three glaucoma subgroups (P < 0.05). An exception to this is PT (b-wave peak to PhNR trough) PhNR amplitude where its reduction was statistically non-significant when comparing between controls and mild glaucoma cases (P = 0.178), and between moderate and severe glaucoma cases (P = 0.714). PhNR amplitudes and PhNR/b-wave ratios correlated significantly with SAP and OCT parameters (P < 0.05). Conclusion: PhNR correlates well with SAP and OCT parameters in glaucoma assessment. PhNR could be a valuable supplementary tool for objective assessment of the RGCs' function in glaucoma.

Choroidal thickness in relation to urinary albumin excretion rate in type 2 diabetes mellitus without retinopathy.

BACKGROUND: To evaluate choroidal thickness (CT) in diabetic patients without diabetic retinopathy (DR) in relation to the urinary albumin excretion rate (UAER). METHODS: This is a prospective case-control study that included a consecutive sample of 120 patients with type 2 diabetes without clinically evident DR and a group of 60 matched healthy controls. Diabetic patients were included in two groups according to their UAER (normoalbuminuria and microalbuminuria). Complete ophthalmological examination was performed followed by optical coherence tomography (SD-OCT) for retinal and choroidal assessment. Twenty-four-hour urine samples were collected for UAER and blood samples for HbA1c and serum creatinine were obtained. RESULTS: The study included 180 eyes from 180 subjects in three groups. Patients with higher levels of albuminuria had a thinner choroid than normal controls, with decremental thinning as albuminuria progressed. Diabetics with normoalbuminuria showed no significant differences from controls. Choroidal thickness showed a significant moderate negative correlation with UAER (r = - 0.58, p < 0.001). Multiple regression analyses for diabetic patients with microalbuminuria demonstrated that UAER is the most important determinant of subfoveal choroidal thickness (SFCT) (p < 0.001). CONCLUSIONS: Decreased CT was significantly correlated with UAER in diabetic patients without retinopathy and otherwise normal kidney functions. This decrease in thickness might be a predictor of DR.

Multifocal visual evoked potential for evaluation of open-angle glaucoma.

Background: To correlate multifocal visual evoked potential (mfVEP) findings with static automated perimetry (SAP) and spectral-domain optical coherence tomography (SD-OCT) in eyes with primary open- angle glaucoma (POAG). Methods: This cross-sectional study included a consecutive sample of 40 eyes of 40 patients with POAG. The participants underwent a complete ophthalmologic assessment, axial length (AL) measurement, and assessments with SAP, SD-OCT, and mfVEP. Results: POAG cases were aged 49.70 (14.16) years (mean [SD]) and most were females (n = 24, 60%). For eyes of patients with POAG, the mfVEP upper-ring signal-to-noise ratio (SNR) showed a significant negative correlation with best-corrected logMAR visual acuity (r = - 0.33; P = 0.038), and a significant positive correlation with the superior hemifield of the visual field (VF) and the inferior-quadrant retinal nerve fiber layer (RNFL) thickness (r = + 0.34; P = 0.030; r = + 0.51; P < 0.001, respectively). Similarly, the mfVEP lower-ring SNR showed a significant negative correlation with best-corrected logMAR visual acuity (r = - 0.36; P = 0.024) and a significant positive correlation with the inferior hemifield of the VF and superior quadrant RNFL thickness (r = + 0.55; P < 0.001 and r = + 0.70; P < 0.001, respectively). Conclusions: mfVEP is a promising tool for objective assessment of the VF in patients with POAG, as it is positively correlated with the VF and OCT RNFL thickness. Future longitudinal studies with a larger sample size and a specific glaucoma subtype, along with multiple follow-up evaluations, are warranted to confirm our preliminary results.

EFFECT OF SMOKING ON MACULAR FUNCTION AND STRUCTURE IN ACTIVE SMOKERS VERSUS PASSIVE SMOKERS.

PURPOSE: The aim is to study the effects of cigarette smoking on the structural and functional alterations of the macula in eyes of healthy young smokers. METHODS: Cross-sectional clinical study included 100 active smokers (Group 1) and 100 age- and sex-matched healthy passive smokers (Group 2). All participants underwent a complete ophthalmologic assessment, axial length measurement, central corneal thickness measurement, spectral domain optical coherence tomography, and multifocal electroretinogram. Urine samples were collected to measure urinary levels of cotinine and creatinine with subsequent calculation of the cotinine creatinine ratio. RESULTS: Central foveal thickness (255.62 ± 17.23 and 264.75 ± 17.35 µm, respectively, with P = 0.0003) and subfoveal choroidal thickness (377.48 ± 30.32 and 385.08 ± 21.10 µm, respectively, with P = 0.04) were significantly lower in active smokers than those of passive smokers. Retinal response density of ring 1 (31.08 ± 2.29 and 33.46 ± 3.83 nV/deg, respectively, with P < 0.001) and Ring 1 (R1) P1 amplitude (0.81 ± 0.07 and 0.95 ± 0.16 µV, respectively, with P < 0.001) were significantly lower, whereas R1 P1 latency (43.02 ± 0.97 and 40.39 ± 2.08 milliseconds, respectively, with P < 0.001) was significantly longer in active smokers than those of passive smokers. The mf-ERG ring ratios were significantly lower in the active smokers than those of passive smokers. CONCLUSION: In the absence of clinically apparent foveal toxicity, CFT, SFCT together with ring amplitude ratio could be used as good predictors of subclinical nicotine induced foveal changes.

Pattern Visual Evoked Potential, Pattern Electroretinogram, and Retinal Nerve Fiber Layer Thickness in Patients with Migraine during and after Aura.

PURPOSE: To study pattern visual evoked potential (PVEP), pattern electroretinogram (PERG), and retinal nerve fiber layer (RNFL) thickness in patients with migraine during and after aura. MATERIALS AND METHODS: We included 60 eyes of 60 patients with migraine (Group 1) and 30 healthy volunteers (30 eyes) as controls (Group 2). Group 1 was studied twice, during a visual aura (1-a) and in between attacks (1-b). All participants underwent full ophthalmological examination, PVEP, PERG, and optical coherence tomographyOCT imaging of the RNFL thickness for each patient. RESULTS: RNFL thickness was found to be thinner in patients during the aura compared to controls. It increased significantly post-aura but remained lower than the controls. Prolonged P100 latency and decreased amplitude were found in patients during aura compared to controls with significant change in between attacks to values comparable to the controls. We found prolonged N95 latency and decreased amplitude in patients during aura compared to controls with significant change post-aura to values comparable to the controls. There was positive correlation between average RNFL thicknesses and VA and spherical equivalent; but it showed negative correlation with duration of migraine, attack duration, and aura duration. Multiple regression analysis showed that the most important determinants of average RNFL thickness in patients of migraine were attack and aura duration (beta = -0.21 and -0.26 and p = 0.03 and 0.04, respectively). CONCLUSION: Migraine attacks impose both functional and structural retinal changes. The functional changes are fully reversible after the aura but not the structural ones. So, vigorous prevention of migraine attacks would be protective for retina.

Effect of Active and Passive Smoking on Retinal Nerve Fibre Layer and Ganglion Cell Complex.

Aim. To evaluate the possible structural and functional changes in the retinal nerve fibre layer (RNFL) and the ganglion cell complex (GCC) of chronic smokers and compare them with those of passive healthy smokers using spectral domain optical coherence tomography (SD-OCT) and pattern electroretinogram (PERG). Materials and Methods. We include 80 active chronic smokers and 80 age- and sex-matched healthy passive smokers. After a full ophthalmological examination, SD-OCT and PERG were tested for all participants. Urinary levels of cotinine and creatinine with subsequent calculation of the cotinine creatinine ratio (CCR). Results. Inferior and superior quadrants of RNFL were thinner in group I, but nasal and temporal quadrants did not show significant difference between the groups. There were no significant differences of GCC values between the two groups. There was no significant difference of PERG-P50 amplitude and latency; however, PERG-N95 showed significant difference between the two groups. Multiple regression analyses demonstrated that the number of cigarettes/day, urinary cotinine, and PERG-N95 amplitude are the most important determinants for both superior and inferior RNFL thicknesses. Conclusion. RNFL thickness decreases in chronic, healthy, heavy cigarette smokers, and this thinning is related to the number of cigarettes/day, urinary cotinine, and PERG-N95 latency and amplitude.

Relationship between functional and structural retinal changes in myopic eyes.

BACKGROUND: The aim of this study was to investigate the retinal structure in different grades of myopia and correlate it with the functional changes detected with multifocal electroretinogram (mf-ERG) and try to show the most important determining factors. METHODS: The study included 80 participants divided into four groups according to their spherical equivalent refractive error, namely, emmetropia (within ± 0.50 D), mild myopia group (greater than -0.50 to -3.00 D), moderate myopia group (more than -3.00 to -6.00 D) and high myopia group (greater than -6.00 D). Full ophthalmologic examination was performed for all participants, including visual acuity (VA), slitlamp examination, Goldmann applanation tonometry, indirect ophthalmoscopy, axial length (AL) measurement, retinal nerve fibre layer thickness assessment and mf-ERG stimulation. RESULTS: Axial length was significantly higher in myopes than emmetropes; also it was higher the greater the degree of myopia. There was a reduction in the amplitude and prolongation of implicit times of mf-ERG in myopia. Also P1 implicit time of the mf-ERG response was prolonged the greater the degree of myopia. The retinal nerve fibre layer was significantly thinner in myopic groups than the emmetropic group. The thinning of the retinal nerve fibre layer increased the more the degree of myopia. Multiple regression analysis of myopic patients showed that AL is the most important determinant of most of the mf-ERG five-rings retinal response density (RRD), mf-ERG four-quadrant (Q) RRD, most of the five-rings P1 amplitude and all five-rings latencies. The most important determinant factors of mean Q RRD were VA, AL and retinal nerve fibre layer thickness. CONCLUSION: The retina of the myope is subject to both structural and functional alterations compared to that of the emmetrope. Significant correlations exist between the functional and structural changes and can be explained on bases of longer AL and increasing myopic refraction.

CORRELATION BETWEEN SUBFOVEAL CHOROIDAL THICKNESS AND FOVEAL THICKNESS IN THALASSEMIC PATIENTS.

PURPOSE: To assess the impact of two iron chelation modalities in thalassemic patients on foveal and subfoveal choroidal thickness. METHODS: The study included 60 ß-thalassemia major patients. They included 30 patients on oral deferasirox after a period of subcutaneous deferoxamine (Group 2) and 30 patients on subcutaneous deferoxamine (Group 3). Thirty age- and sex-matched healthy children were included as a control group (Group 1). All participants underwent a complete ophthalmologic evaluation and Spectral Domain Optical Coherence Tomography. RESULTS: Age, gender, intraocular pressure, best-corrected visual acuity, and refraction were not statistically different between the three studied groups. Ferritin level, pretransfusion hemoglobin, serum iron, and duration of thalassemia were not statistically different between the two thalassemic groups. Foveal thickness in Group 1 (225.15 ± 17.35 µm) was statistically higher than in Group 2 (210.53 ± 21.73 µm) (P < 0.001) and Group 3 (200.15 ± 7.34 µm) (P < 0.001). It was statistically higher in Group 2 than in Group 3 (P = 0.001). Subfoveal choroidal thickness in Group 1 (279.70 ± 32.54 µm) was statistically higher than in Group 2 (255.80 ± 19.20 µm) (P < 0.001) and Group 3 (248.28 ± 20.43 µm) (P < 0.001). It was statistically higher in Group 2 than in Group 3 (P < 0.05). CONCLUSION: Thalassemic patients can develop a significant decrease in foveal thickness because of the inevitable use of chelation therapy. Deferoxamine as a chelating agent can affect foveal thickness more than the oral form (deferasirox).