Consuelo Pérez-Rico

Effect of diabetes mellitus on Corvis ST measurement process

Diabetes mellitus (DM) affects corneal biomechanical parameters. We compared analyses using ORA (Ocular response analyser) and Corvis ST to determine the influence of disease duration, hyperglycaemia and haemoglobin A1c (HbA1c) levels on these parameters.

Evaluation of the visual function in obstructive sleep apnea syndrome patients and normal-tension glaucoma by means of the multifocal visual evoked potentials

BackgroundThis study was designed to objectively evaluate visual function and the causal relationship between sleep apnea and optic nerve dysfunction in patients with obstructive sleep apnea syndrome (OSAS) with or without diagnosis of normal-tension glaucoma (NTG) using multifocal visual evoked potentials (mfVEP).MethodsThis observational, cross-sectional study assessed 20 patients with recently diagnosed OSAS with or without NTG. Diagnosis of sleep apnea was based on overnight polysomnography (ApnoeScreen). All participants underwent a complete physical and ophthalmologic examination. MfVEP recordings obtained using VERIS software (Electro-Diagnostic Imaging, San Mateo, USA), SITA-standard 30-2 automated perimetry (Humphrey Visual Field Analyzer II) and optic coherence tomography (Topcon 3D OCT-1000) exams were performed to evaluate the changes.ResultsAbnormal mfVEP amplitudes defects (interocular and monocular probability analysis) were found in 40% of the eyes in the non-glaucoma group and in 90% of eyes of the NTG patients. As well, delayed mfVEP latencies (interocular and monocular probability analysis) were seen in 30 and 60% of the eyes of the non-glaucoma and NTG groups, respectively. The average RNFL (retinal nerve fiber layer) thickness was significantly reduced in the NTG eyes compared to the control database and the non-glaucoma eyes. On the Humphrey Visual Field total deviation analysis, all the NTG eyes showed significant clusters of abnormal points but none was detected in the non-glaucoma group eyes. However, the mfVEP amplitude and latency did not show any significant correlation with the standard perimetry and OCT variables, because the mfVEP technique was able to detect far more early visual defects in these patients. Systolic blood pressure, sleep efficiency, arousal index, mean and minimum arterial oxygen saturation (SaO2), time SaO2 < 90%, oxyhemoglobin desaturation index, number of central and mixed apneas and apnea-hipopneas index were shown to be significantly correlated with mfVEP amplitude and latency.ConclusionsA significant incidence of subclinical optic nerve involvement, not detected with other structural and psychophysics diagnostic techniques was seen by means of the mfVEP. In this sense, the mfVEP may be a useful diagnostic tool in the clinic for early diagnosis and monitoring of optic nerve function abnormalities in patients with OSAS.

Obstructive sleep apnea–hypopnea syndrome (OSAHS) and glaucomatous optic neuropathy

Obstructive sleep apnea–hypopnea syndrome (OSAHS) is becoming widely accepted as a risk factor for glaucoma. We discuss the proposed mechanism involved in the pathogenesis of glaucoma in OSAHS, and review the published data on the association between these two conditions, as well as papers regarding functional and structural tests related with glaucomatous damage. There is increasing evidence that the prevalence of glaucoma is higher in OSAHS patients, especially in those with severe disease with apnea-hypopnea index (AHI) >30, and also that sleep disorders may be more frequent in patients with glaucoma, especially in those with normal tension glaucoma (NTG). Several ophthalmic signs and symptoms have been associated with this condition. Raised intraocular pressure (IOP), possibly related to increased body mass index, thinning of retinal nerve fiber layer (RNFL), and alteration of visual field (VF) indices has been demonstrated in many studies, in patients with no history of glaucoma or evidence of glaucomatous changes in the ophthalmic examination. A correlation of AHI with RNFL and VF indices has been described in some studies. Finally, corneal thinning, suspicious glaucomatous disc changes and anomalies in electrophysiological tests such as multifocal visual evoked potential have been described in patients with OSAHS, even in patients with normal findings in the optic nerve and VF, suggesting subclinical optic nerve involvement not detectable in conventional ophthalmic examinations. The pathogenesis of optic nerve involvement has been related to vascular and mechanical factors. Vascular factors include recurrent hypoxia with increased vascular resistance, autonomic deregulation, oxidative stress and inflammation linked to hypoxia and subsequent reperfusion, decreased cerebral perfusion pressure and direct hypoxic damage to the optic nerve. Proposed mechanical factors include increased IOP at night related to supine position and obesity, raised intracranial pressure and elastic fiber depletion in the lamina cribosa and/or trabeculum. In conclusion, ophthalmic evaluation should be recommended in patients with severe OSAHS, and the presence of sleep disorders should be investigated in patients with glaucoma, especially in NTG patients and in those with progressive damage despite controlled IOP, as treatment with continuous positive airway pressure may contribute to stabilizing the progression of glaucomatous damage.

Functional assessment of the visual pathway with multifocal visual evoked potentials, and their relationship with disability in patients with multiple sclerosis.

Objective: To objectively evaluate the visual function, and the relationship between disability and optic nerve dysfunction, in patients with multiple sclerosis (MS) and optic neuritis (ON), using multifocal visual evoked potentials (mfVEP). Methods: This observational, cross-sectional study assessed 28 consecutive patients with clinically definite MS, according to the McDonald criteria, and 19 age-matched healthy subjects. Disability was recorded using the Expanded Disability Status Scale (EDSS) score. The patients’ mfVEP were compared to their clinical, psychophysical (Humphrey perimetry) and structural (optic coherence tomography (OCT)) diagnostic test data. Results: We observed a significant agreement between mfVEP amplitude and Humphrey perimetry/OCT in MS-ON eyes, and between mfVEP amplitude and OCT in MS but non-ON eyes. We found significant differences in EDSS score between patients with abnormal and normal mfVEP amplitudes. Abnormal mfVEP amplitude defects (from interocular and monocular probability analysis) were found in 67.9% and 73.7% of the MS-ON and MS-non-ON group eyes, respectively. Delayed mfVEP latencies (interocular and monocular probability analysis) were seen in 70.3% and 73.7% of the MS-ON and MS-non-ON groups, respectively. Conclusions: We found a significant relationship between mfVEP amplitude and disease severity, as measured by EDSS score, that suggested there is a role for mfVEP amplitude as a functional biomarker of axonal loss in MS.

Evaluation of visual structural and functional factors that predict the development of multiple sclerosis in clinically isolated syndrome patients.

PURPOSE To evaluate visual pathway structure and function in patients with clinical isolated syndrome (CIS) by using spectral-domain optical coherence tomography (OCT) and multifocal visual-evoked potentials (mfVEP), predicting CIS conversion to clinically definite multiple sclerosis (MS). METHODS This observational, longitudinal study assessed the eyes with no previous history of optic neuritis of 29 consecutive patients with CIS according to the McDonald criteria. The relationships of the mfVEP results with the clinical findings, and psychophysical (Humphrey perimetry) and structural (OCT) diagnostic test data were investigated. RESULTS The mfVEP amplitude responses (interocular and monocular probability analysis) showed abnormal cluster visual field defects in 48.3% of the CIS eyes, whereas mfVEP latency analysis showed significant delays in 20.7%. The OCT average retinal nerve fiber layer thickness (RNFLT) was significantly reduced compared with the control group (P = 0.02). Significant differences between CIS eyes with abnormal and normal mfVEP latencies were found for the OCT RNFLT (P < 0.001) with a longer latency being linked to more severe axonal damage. Using multivariate logistic regression analysis, OCT average RNFLT was found to be an independent predictor of clinically definitive MS diagnosis at 12 months. CONCLUSIONS The combined use of OCT and mfVEP is helpful to detect significant subclinical visual pathway abnormalities and axonal loss in CIS patients. Retinal axonal loss measured by OCT is an important prognostic factor of conversion to MS in patients with CIS in absence of symptomatic optic neuritis.

Effect of intravitreal ranibizumab on corneal endothelium in age-related macular degeneration.

Purpose: To determine the effect of intravitreal injection of ranibizumab on the corneal endothelium in patients with choroidal neovascularization in age-related macular degeneration. Methods: Observational prospective case series study. Fifty-two eyes of 52 consecutive patients (29 men, 23 women; age range, 61-80 years) were evaluated. All participants received monthly intravitreal injections of (0.05 mL, 0.5 mg) ranibizumab for 3 consecutive months; the follow-up period was 6 months. Central corneal specular microscopy was performed before injection and at 7 days and 6 months after the first intravitreal injection. The endothelial cell density, coefficient of variation of cell size, and percentage of hexagonal cells were analyzed, and the central corneal thickness was measured. Results: There were no significant differences in the endothelial cell densities, coefficient of variation of cell sizes, and percentage of hexagonal cells values before injection and at 7 days and 6 months after the first intravitreal ranibizumab injection (P = 0.987, P = 0.822, and P = 0.918, respectively). There was also no significant difference in central corneal thickness measurements before injection and at 7 days and 6 months after the first intravitreal ranibizumab injection (P = 0.325). Conclusion: Repeated intravitreal injections of 0.5 mg of ranibizumab do not seem to cause substantial changes in the corneal endothelium at 6 months.

Intraoperative mitomycin C and corneal endothelium after pterygium surgery.

Purpose: To determine the effect of mitomycin C (MMC) on the corneal endothelium after primary pterygium surgery. Methods: This prospective, interventional, nonrandomized, observer-masked study included 46 consecutive patients (51 eyes) with primary pterygium. The bare sclera technique with 1-minute application of 0.02% MMC intraoperatively was used in all cases. The follow-up period was 3 months. Preoperative and postoperative central corneal specular microscopy was performed. The endothelial cell density, coefficient of variation of cell size, and percentage of hexagonal cells were analyzed, and the corneal thickness was measured. Results: The mean endothelial cell densities preoperatively and 3 months postoperatively were 2382.35 ± 342.07 cells per square millimeter (range, 1020-3129) and 2385.02 ± 356.83 cells per square millimeter (range, 1001-3151), respectively (P = 0.96). The mean coefficients of variation of cell size preoperatively and 3 months postoperatively were 34.31 ± 5.62 (range, 22-49) and 35.29 ± 7.50 (range, 22-55), respectively (P = 0.17). The mean percentages of hexagonal cells values preoperatively and 3 months postoperatively were 52.98 ± 7.32 (range, 32-71) and 51.61 ± 8.98 (range, 32-67), respectively (P = 0.48). The mean pachymetry measurements preoperatively and 3 months postoperatively were 506.65 ± 36.87 μm (range, 411-583) and 502.08 ± 41.33 μm (range, 411-593), respectively (P = 0.99). Conclusions: One intraoperative application of 0.02% MMC for 1 minute after primary pterygium surgery does not seem to cause substantial changes in the corneal endothelium at 3 months.

Effect of topical 0.05% cyclosporine A on corneal endothelium in patients with dry eye disease.

AIM To determine the effect of topical 0.05% cyclosporine A (CsA) on corneal endothelium in patients with dry eye disease. METHODS Observational, prospective, case series study. Fifty-five eyes of 29 consecutive patients (9 males and 20 females; median age: 66.8 years, interquartile range: 61-73.2 years) with moderate-severe dry eye disease were evaluated. All patients were treated with topical 0.05% CsA ophthalmic emulsion twice a day in addition to lubricant eyedrops 5 times a day. The follow-up period was 12 months. Before treatment and at 3 and 12 months post-treatment central corneal specular microscopy was performed. The endothelial cell density (ECD), coefficient of variation of cell size (CoV), and percentage of hexagonal cells (Hex %) were analyzed. RESULTS The median ECDs pre-treatment and at 3 and 12 months post-treatment were 2 352.5/mm(2) (interquartile range, 2 178-2 548.5), 2364/mm(2) (interquartile range, 2 174.25-2 657.5), and 2366 cells/mm(2) (interquartile range, 2 174.75-2 539.75), respectively (P=0.927, one way ANOVA). The median CoVs pre-treatment and at 3 and 12 months post-treatment were 34.5 (interquartile range, 30-37), 35 (interquartile range, 30-38), and 34 (interquartile range, 30.75-38.25), respectively (P=0.7193, one way ANOVA). The median Hex % values pre-treatment and at 3 and 12 months post-treatment were 53 (interquartile range, 47-58), 54 (interquartile range, 45.75-59), and 50.5 (interquartile range, 45.75-58), respectively (P=0.824, one way ANOVA). CONCLUSION Treatment of patients with dry eye disease for 12 months with topical 0.05% CsA does not seem to cause substantial changes on corneal endothelium.

Multifocal electroretinogram diagnosis of glaucoma applying neural networks and structural pattern analysis

Glaucoma is a chronic ophthalmological disease that affects 5% of the 40-60-year-old population and can lead to irreversible blindness. The multifocal electroretinogram (mfERG) is a recently developed diagnostic technique that provides objective spatial data on the visual pathway and may be of potential benefit in early diagnosis of glaucoma. This paper analyses 13 morphological characteristics that define mfERG recordings and classifies them using a radial basis function network trained with the Extreme Learning Machine algorithm. When used to detect glaucomatous sectors, the method proposed produces sensitivity and specificity values of over 0.8.

Optical coherence tomography features of sub-internal limiting membrane hemorrhage and temporary premacular cavity following Nd-YAG laser membranotomy in Valsalva retinopathy

(Fig. 1c). Although she received urokinase and hyperbaric oxygen treatment, her right BCVA remains 0.1. A 61-year-old woman developed blurred vision in the right eye after 6 months of treatment with pegylated interferon-α and ribavirin. Ophthalmologic evaluation revealed scattered or fl ame-shaped retinal hemorrhage (Fig. 2). Since she had never undergone ophthalmologic examination, information regarding her previous retinal status was unavailable. Her BCVA was 0.1 (OD), which recovered to 1.2 (OD) after treatment with urokinase and hyperbaric oxygen.