Confocal Optical Coherence Tomography Research Articles

Line-field confocal optical coherence tomography for high-resolution noninvasive imaging of skin tumors.

An optical technique called line-field confocal optical coherence tomography (LC-OCT) is introduced for high-resolution, noninvasive imaging of human skin in vivo. LC-OCT combines the principles of time-domain optical coherence tomography and confocal microscopy with line illumination and detection using a broadband laser and a line-scan camera. LC-OCT measures the echo-time delay and amplitude of light backscattered from cutaneous microstructures through low-coherence interferometry associated with confocal spatial filtering. Multiple A-scans are acquired simultaneously while dynamically adjusting the focus. The resulting cross-sectional B-scan image is produced in real time at 10 frame / s. With an isotropic spatial resolution of ∼1 μm, the LC-OCT images reveal a comprehensive structural mapping of skin at the cellular level down to a depth of ∼500 μm. LC-OCT has been applied to the imaging of various skin lesions, in vivo, including carcinomas and melanomas. LC-OCT images are found to strongly correlate with conventional histopathological images. The use of LC-OCT as an adjunct tool in medical practice could significantly improve clinical diagnostic accuracy while reducing the number of biopsies of benign lesions.

Acne vulgaris severity graded by in vivo reflectance confocal microscopy and optical coherence tomography.

Acne is an inflammatory disease of the pilosebaceous unit, which can be investigated in vivo using reflectance confocal microscopy (RCM) and optical coherence tomography (OCT). By means of RCM and OCT to identify morphological characteristics of acne that may be associated with clinical acne severity. Patients with mild to moderate facial acne (n = 14, Investigators Global Assessment scale, IGA 1-3), and healthy participants (n = 7, IGA 0) were included in this explorative study. A total of 108 RCM image blocks and 54 OCT scans (each RCM and OCT image measuring 6 × 6 mm) were captured from lesional-, perilesional, and lesion-free skin areas. Acne lesions, infundibular regions of follicles and inflammation degree were compared in acne patients and healthy participants. Combined use of RCM and OCT demonstrated infundibular morphology, acne lesions, and blood flow. RCM images of perilesional- and lesion-free skin in acne patients revealed follicle infundibula with hyperkeratinized borders and abundant keratin plugs, contrasting skin of healthy participants. Higher acne severity related to increased number of follicles with hyperkeratotic borders (P = 0.04) and keratin plugs (P = 0.006), increased infundibulum diameter (P < 0.001), increased density of inflammatory cells (P < 0.001), and blood flow (P = 0.03). Acne lesion morphology was not associated with acne severity. Combined use of RCM and OCT elucidated distinctive follicle infundibulum characteristics and inflammation degree that were associated with acne severity. Future trials may apply imaging techniques to support clinical acne grading, and monitor treatment efficacy. Lasers Surg. Med. 51:104-113, 2019. © 2018 Wiley Periodicals, Inc.

Detecting murine Inflammatory Bowel Disease using Optical Coherence Elastography.

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that causes regions of ulceration within the interior of the colon. UC is estimated to afflict hundreds of thousands of people in the United States alone. Ultrasonic techniques can detect colitis, but have limited spatial resolution, which frequently results in underdiagnoses. Nevertheless, clinical diagnosis of colitis is still generally performed via colonoscopy. Optical techniques such as confocal microscopy and optical coherence tomography (OCT) have been proposed as higher resolution alternative imaging modalities to detect colitis. Additionally, IBD can potentially alter tissue biomechanical properties, which cannot be quantified from structural imaging alone. Elastography is a potential method to assess colon biomechanical properties to provide additional contrast for distinguishing healthy and diseased colon tissue. In this work, we induced elastic waves in ex vivo mouse colon tissue using a focused air-pulse. The elastic waves were detected using a phase-stabilized swept source optical coherence elastography system, and the wave velocity was translated into stiffness. Measurements were taken at six random positions for each sample in order to assess regional sample elasticity. The results show distinct differences ($p \lt 0.05$) in the stiffness between healthy and IBD-diseased samples, with a Young's Modulus of $10.2 \pm 3.7$ kPa and $4.9 \pm 0.3$ kPa, respectively. Dispersion analysis presents another parameter to distinguish tissue health. The high frequency components of the phase velocity dispersion curve indicate a variation between healthy and IBD colonic tissue. Our results show that OCE may be useful for detecting IBD noninvasively.

Pseudo‐Kaposi sarcoma: report of a case investigated by dermoscopy, reflectance confocal microscopy and optical coherence tomography

Pseudo‐Kaposi sarcoma: report of a case investigated by dermoscopy, reflectance confocal microscopy and optical coherence tomography

Confocal Laser Endomicroscopy and Optical Coherence Tomography for the Diagnosis of Prostate Cancer: A Needle-Based, In Vivo Feasibility Study Protocol (IDEAL Phase 2A).

BackgroundFocal therapy for prostate cancer has been proposed as an alternative treatment to whole-gland therapies in selected men to diminish side effects in localized prostate cancer. As nowadays imaging cannot offer complete prostate cancer disease characterization, multicore systematic biopsies are recommended (transrectal or transperineal). Optical imaging techniques such as confocal laser endomicroscopy and optical coherence tomography allow in vivo, high-resolution imaging. Moreover, they can provide real-time visualization and analysis of tissue and have the potential to offer additive diagnostic information.ObjectiveThis study has 2 separate primary objectives. The first is to assess the technical feasibility and safety of in vivo focal imaging with confocal laser endomicroscopy and optical coherence tomography. The second is to identify and define characteristics of prostate cancer and normal prostate tissue in confocal laser endomicroscopy and optical coherence tomography imaging by comparing these images with the corresponding histopathology.MethodsIn this prospective, in vivo feasibility study, needle-based confocal laser endomicroscopy and optical coherence tomography imaging will be performed before transperineal template mapping biopsy or radical prostatectomy. First, confocal laser endomicroscopy and optical coherence tomography will be performed in 4 patients (2 for each imaging modality) undergoing transperineal template mapping biopsy to assess the feasibility and safety of confocal laser endomicroscopy and optical coherence tomography. If proven to be safe and feasible, confocal laser endomicroscopy and optical coherence tomography will be performed in 10 patients (5 for each imaging modality) undergoing radical prostatectomy. Confocal laser endomicroscopy and optical coherence tomography images will be analyzed by independent, blinded observers. Confocal laser endomicroscopy– and optical coherence tomography–based qualitative and quantitative characteristics and histopathology will be compared. The study complies with the IDEAL (Idea, Development, Exploration, Assessment, Long-term study) stage 2a recommendations.ResultsAt present, the study is enrolling patients and results and outcomes are expected in 2019.ConclusionsConfocal laser endomicroscopy and optical coherence tomography are promising optical imaging techniques that can visualize and analyze tissue structure, possible tumor grade, and architecture in real time. They can potentially provide real-time, high-resolution microscopic imaging and tissue characteristics of prostate cancer in conjunction with magnetic resonance imaging or transrectal ultrasound fusion-guided biopsy procedures. This study will provide insight into the feasibility and tissue-specific characteristics of confocal laser endomicroscopy and optical coherence tomography for real-time optical analysis of prostate cancer.Trial RegistrationClinicalTrials.gov NCT03253458; https://clinicaltrials.gov/ct2/show/NCT03253458 (Archived by WebCite at http://www.webcitation.org/6z9owM66B)Registered Report IdentifierRR1-10.2196/9813

Reflectance confocal microscopy and optical coherence tomography for the diagnosis of bullous pemphigoid and pemphigus and surrounding subclinical lesions.

Diagnosis of bullous pemphigoid (BP) and pemphigus is based on clinical features, histology, immunofluorescence and laboratory data. To evaluate features of BP and pemphigus at reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) in order to provide a rapid non-invasive bed-side diagnosis. Secondary objective was to evaluate the detectability of clinically non-visible lesions. This was an observational, retrospective, multicentre study in which patients with suspicious lesions for BP or pemphigus underwent clinical assessment, RCM, OCT, blood tests and skin biopsy for histological and direct immunofluorescence examinations from January 2014 to December 2015. A total of 72 lesions in 24 selected patients were evaluated. Additionally, apparently unaffected skin at two different distances [near (1-2 cm) and far (2-3 cm)] from each lesion was examined to test subclinical lesion detectability. RCM was able to detect subepidermal and intra-epidermal blisters, respectively, in 75% and 50% of the patients affected by BP and pemphigus. At OCT, the exact blister level was identified in all patients. Acantholytic cells were observed only at RCM in pemphigus (62.5%). Fibrin deposition inside the blisters was only found in BP, evidenced both at RCM and OCT. Among patients with BP, subclinical blisters were detected in nine (9.4%) clinically healthy skin, while among patients with pemphigus were observed in 10 (20.8%) apparently unaffected skin. RCM and/or OCT provide useful information for a rapid diagnosis of BP and pemphigus and for the identification of biopsy site. Combined use of RCM and OCT is optimal because associates the higher resolution of RCM with the greater penetration depth of OCT. OCT could be an optimal tool for treatment monitoring, especially in the cases of subclinical lesions. However, histopathologic and immunologic examinations remain the gold standard for establishing the final diagnosis.

Full depth measurement of tenofovir transport in rectal mucosa using confocal Raman spectroscopy and optical coherence tomography.

The prophylactic activity of antiretroviral drugs applied as microbicides against sexually transmitted HIV is dependent upon their concentrations in infectable host cells. Within mucosal sites of infection (e.g., vaginal and rectal mucosa), those cells exist primarily in the stromal layer of the tissue. Traditional pharmacokinetic studies of these drugs have been challenged by poor temporal and spatial specificity. Newer techniques to measure drug concentrations, involving Raman spectroscopy, have been limited by laser penetration depth into tissue. Utilizing confocal Raman spectroscopy (RS) in conjunction with optical coherence tomography (OCT), a new lateral imaging assay enabled concentration distributions to be imaged with spatial and temporal specificity throughout the full depth of a tissue specimen. The new methodology was applied in rectal tissue using a clinical rectal gel formulation of 1% tenofovir (TFV). Confocal RS revealed diffusion-like behavior of TFV through the tissue specimen, with significant partitioning of the drug at the interface between the stromal and adipose tissue layers. This has implications for drug delivery to infectable tissue sites. The new assay can be applied to rigorously analyze microbicide transport and delineate fundamental transport parameters of the drugs (released from a variety of delivery vehicles) throughout the mucosa, thus informing microbicide product design.

Actinic Keratosis and Non-Invasive Diagnostic Techniques: An Update.

Actinic keratosis represents the earliest manifestation of non-melanoma skin cancer. Because of their risk of progression to invasive squamous cell carcinoma, an earlier diagnosis and treatment are mandatory. Their diagnosis sometimes could represent a challenge even for expert dermatologists. Dermoscopy, confocal laser microscopy and optical coherence tomography could help clinicians in diagnosis.

Optical and Cross-Sectional Imaging Technologies for Bladder Cancer.

Optical and cross-sectional imaging plays critical roles in bladder cancer diagnostics. White light cystoscopy remains the cornerstone for the management of non-muscle-invasive bladder cancer. In the last decade, significant technological improvements have been introduced for optical imaging to address the known shortcomings of white light cystoscopy. Enhanced cystoscopy modalities such as blue light cystoscopy and narrowband imaging survey a large area of the urothelium and provide contrast enhancement to detect additional lesions and decrease cancer recurrence. However, higher false-positive rates accompany the gain of sensitivity. Optical biopsy technologies, including confocal laser endomicroscopy and optical coherence tomography, provide cellular resolutions combined with subsurface imaging, thereby enabling optical-based cancer characterization, and may lead to real-time cancer grading and staging. Coupling of fluorescently labeled binding agents with optical imaging devices may translate into high molecular specificity, thus enabling visualization and characterization of biological processes at the molecular level. For cross-sectional imaging, upper urinary tract evaluation and assessment potential extravesical tumor extension and metastases are currently the primary roles, particularly for management of muscle-invasive bladder cancer. Multi-parametric MRI, including dynamic gadolinium-enhanced and diffusion-weighted sequences, has been investigated for primary bladder tumor detection. Ultrasmall superparamagnetic particles of iron oxide (USPIO) are a new class of contrast agents that increased the accuracy of lymph node imaging. Combination of multi-parametric MRI with positron emission tomography is on the horizon to improve accuracy rates for primary tumor diagnostics as well as lymph node evaluation. As these high-resolution optical and cross-sectional technologies emerge and develop, judicious assessment and validation await for their clinical integration toward improving the overall management of bladder cancer.

Non‐invasive evaluation of Secukinumab efficacy in severe plaque psoriasis with confocal microscopy and optical coherence tomography: A case report

Skin Research and TechnologyVolume 24, Issue 1 p. 160-162 LETTER TO THE EDITOR Non-invasive evaluation of Secukinumab efficacy in severe plaque psoriasis with confocal microscopy and optical coherence tomography: A case report G. Odorici, Corresponding Author G. Odorici [email protected] orcid.org/0000-0002-5910-8994 Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy Correspondence Dr. Giulia Odorici, Department of Surgical, Medical, Dental and Morphological Sciences with Interest transplant, Oncological and Regenerative Medicine Dermatology Unit, University of Modena and Reggio Emilia, Modena, Italy. Email: [email protected]Search for more papers by this authorA. Losi, A. Losi Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorS. Ciardo, S. Ciardo Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorG. Pellacani, G. Pellacani Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorA. Conti, A. Conti Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this author G. Odorici, Corresponding Author G. Odorici [email protected] orcid.org/0000-0002-5910-8994 Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy Correspondence Dr. Giulia Odorici, Department of Surgical, Medical, Dental and Morphological Sciences with Interest transplant, Oncological and Regenerative Medicine Dermatology Unit, University of Modena and Reggio Emilia, Modena, Italy. Email: [email protected]Search for more papers by this authorA. Losi, A. Losi Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorS. Ciardo, S. Ciardo Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorG. Pellacani, G. Pellacani Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this authorA. Conti, A. Conti Department of Dermatology, University of Modena and Reggio Emilia, Modena, ItalySearch for more papers by this author First published: 25 October 2017 https://doi.org/10.1111/srt.12409Citations: 10Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume24, Issue1February 2018Pages 160-162 RelatedInformation

Label-free analysis of tenofovir delivery to vaginal tissue using co-registered confocal Raman spectroscopy and optical coherence tomography.

Vaginally applied microbicide products offer a female-controlled strategy for preventing sexual transmission of HIV. Microbicide transport processes are central to their functioning, and there is a clear need for a better understanding of them. To contribute to that end, we developed an assay to analyze mass transport rates of microbicide molecules within the epithelial and stromal layers of polarized vaginal mucosal tissue during contact with a gel vehicle. The assay utilizes a new diffusion chamber mounted in a custom instrument that combines confocal Raman spectroscopy and optical coherence tomography. This measures depth-resolved microbicide concentration distributions within epithelium and stroma. Data for a tenofovir gel were fitted with a compartmental diffusion model to obtain fundamental transport properties: the molecular diffusion and partition coefficients in different compartments. Diffusion coefficients in epithelium and stroma were computed to be 6.10 ± 2.12 x 10−8 and 4.52 ± 1.86 x 10−7 cm2/sec, respectively. The partition coefficients between epithelium and gel and between stroma and epithelium were found to be 0.53 ± 0.15 and 1.17 ± 0.16, respectively. These drug transport parameters are salient in governing the drug delivery performance of different drug and gel vehicle systems. They can be used to contrast drugs and vehicles during product design, development and screening. They are critical inputs to deterministic transport models that predict the gels’ pharmacokinetic performance, which can guide improved design of products and optimization of their dosing regimens.

Optical improvements in the diagnosis of bladder cancer: implications for clinical practice

For over 100 years white-light cystoscopy has remained the gold-standard technique for the detection of bladder cancer (BCa). Some limitations in the detection of flat lesions (CIS), the differentiation between inflammation and malignancy, the inaccurate determination of the tumor margin status as well as the tumor depth, have led to a variety of technological improvements. The aim of this review is to evaluate the impact of these improvements in the diagnosis of BCa and their effectiveness in clinical practice. A systematic literature search was conducted according to the PRISMA statement to identify studies reporting on imaging modalities in the diagnosis of NMIBC between 2000 and 2017. A two-stage selection process was utilized to determine eligible studies. A total of 74 studies were considered for final analysis. Optical imaging technologies have emerged as an adjunct to white-light cystoscopy and can be classified according to their scope as macroscopic, microscopic and molecular. Macroscopic techniques including photodynamic diagnosis (PDD), narrow-band imaging (NBI) and the Storz Professional Image Enhancement System (IMAGE1 S, formerly known as SPIES) are similar to white-light cystoscopy, but are superior in the detection of bladder tumors by means of contrast enhancement. Especially the detection rate of very mute lesions in the bladder mucosa (CIS) could be significantly increased by the use of these methods. Microscopic imaging techniques like confocal laser endomicroscopy and optical coherence tomography permit a real-time high-resolution assessment of the bladder mucosa at a cellular and sub-cellular level with spatial resolutions similar to histology, enabling the surgeon to perform an 'optical biopsy'. Molecular techniques are based on the combination of optical imaging technologies with fluorescence labeling of cancer-specific molecular agents like antibodies. This labeling is intended to favor an optical distinction between benign and malignant tissue. Optical improvements of the standard white-light cystoscopy have proven their benefit in the detection of BCa and have found their way into clinical practice. Especially the combination of macroscopic and microscopic techniques may improve diagnostic accuracy. Nevertheless, HAL-PDD guided cystoscopy is the only approach approved for routine use in the diagnosis of BCa by most urological associations in the EU and USA to date.

Image-Guided Transurethral Resection of Bladder Tumors - Current Practice and Future Outlooks.

Transurethral resection of bladder tumor (TURBT) under white light cystoscopy (WLC) is the cornerstone for the diagnosis, removal and local staging of non-muscle invasive bladder cancer (NMIBC). Despite technological improvements over the decades, significant shortcomings remain with WLC for tumor detection, thereby impacting the surgical quality and contributing to tumor recurrence and progression. Enhanced cystoscopy modalities such as blue light cystoscopy (BLC) and narrow band imaging (NBI) aid resections by highlighting tumors that might be missed on WLC. Optical biopsy technologies such as confocal laser endomicroscopy (CLE) and optical coherence tomography (OCT) characterize tissue in real-time to ensure a more thorough resection. New resection techniques, particularly en bloc resection, are actively under investigation to improve the overall quality of resections and aid pathologic interpretation. Moreover, new image processing computer algorithms may improve perioperative planning and longitudinal follow-up. Clinical translation of molecular imaging agents is also on the horizon to improve optical diagnosis of bladder cancer. This review focuses on emerging technologies that can impact the quality of TURBT to improve the overall management of NMIBC.

Modern endoscopic imaging tools for urothelial carcinoma of the urinary bladder

Cystoscopy is the gold standard for the initial diagnosis of urothelial carcinoma in the urinary bladder (UCB). White light exhibits significant limitations in its ability to detect flat lesions or carcinoma in situ. Photodynamic Diagnosis (PDD) and Narrow Band Imaging (NBI) are established techniques which may improve the detection rates of UCB and reduce the risk of recurrence. Multiple novel tools have been developed in order to improve the diagnostic accuracy of endoscopic procedures, including Digital Contrast Enhancement Technology, Confocal Laser Endomicroscopy (CLE) and Optical Coherence Tomography (OCT). In future, spectral analysis of urothelial lesions may be achieved by Raman spectroscopy, thus providing information about biological alterations in the tissue. Furthermore, molecular imaging may allow specific targeting by fluorescent antibodies or small molecule agents, thus enabling differential diagnosis of suspicious lesions. Software-based approaches have been developed to incorporate computer-aided diagnosis and improve digital documentation of endoscopic findings. This study reviews current and future developments in the field of modern endoscopy of the urinary bladder and discusses the different approaches.

Apport de la microscopie confocale par réflectance et de la tomographie par cohérence optique dans le diagnostic de tophus goutteux : premier cas rapporté

Apport de la microscopie confocale par réflectance et de la tomographie par cohérence optique dans le diagnostic de tophus goutteux : premier cas rapporté

Non-invasive diagnostic system and its opto-mechanical probe for combining confocal Raman spectroscopy and optical coherence tomography.

Non-invasive optical diagnostic methods allow important information about studied systems to be obtained in a non-destructive way. Complete diagnosis requires information about the chemical composition as well as the morphological structure of a sample. We report on the development of an opto-mechanical probe that combines Raman spectroscopy (RS) and optical coherence tomography (OCT), two methods that provide all the crucial information needed for a non-invasive diagnosis. The aim of this paper is to introduce the technical design, construction and optimization of a dual opto-mechanical probe combining two in-house developed devices for confocal RS and OCT. The unique benefit of the probe is a gradual acquisition of OCT and RS data, which allows to use the acquired OCT images to pinpoint locations of interest for RS measurements. The parameters and the correct functioning of the probe were verified by RS scanning of various samples (silicon wafer and ex vivo tissue) based on their OCT images - lateral as well as depth scanning was performed. Both the OCT and RS systems were developed, optimized and tested with the ultimate aim of verifying the functionality of the probe. Picture: Schematic illustration and visualization of the developed RS-OCT probe.

New technologies for upper tract urothelial carcinoma management.

Image enhancement techniques and optical diagnostic tools have emerged in the quest to improve diagnostics and treatment in patients with upper urinary tract carcinoma (UTUC). The aim of the present report is to describe their mechanisms of action and to assess the current evidence on applicability and utility in UTUC. Image enhancement techniques including narrow band imaging, Image1 S, and photodynamic diagnosis aim at better visualization of malignant urothelium and especially flat tumours or carcinoma in situ which are often difficult to see with white light endoscopy. Conducted studies in the upper tract are scarce but first results show that tumour detection seems to be better for narrow band imaging and photodynamic diagnosis-guided inspection.Optical diagnostic tools as confocal laser endomicroscopy and optical coherence tomography aim at providing real time optical biopsies giving pathologic information. A pilot study of optical coherence tomography proved its feasibility to visualize, grade and stage low and high-grade UTUC. Better visualization of suspect lesions and optical diagnostic techniques providing real time optical biopsies aim to facilitate in higher diagnostic precision and optimal individualized treatment of our patients with UTUC. As the disease is rare, studies are scarce but indispensable for future implication of these techniques.

Comparative investigation of stimulus-evoked rod outer segment movement and retinal electrophysiological activity.

Transient retinal phototropism (TRP) has been observed in rod photoreceptors activated by oblique visible light flashes. Time-lapse confocal microscopy and optical coherence tomography (OCT) revealed rod outer segment (ROS) movements as the physical source of TRP. However, the physiological source of TRP is still not well understood. In this study, concurrent TRP and electroretinogram (ERG) measurements disclosed a remarkably earlier onset time of the ROS movements (≤10 ms) than that (∼38 ms) of the ERG a-wave. Furthermore, low sodium treatment reversibly blocked the photoreceptor ERG a-wave, which is known to reflect hyperpolarization of retinal photoreceptors, but preserved the TRP associated rod OS movements well. Our experimental results and theoretical analysis suggested that the physiological source of TRP might be attributed to early stages of phototransduction, before the hyperpolarization of retinal photoreceptors.

Stimulus-evoked outer segment changes occur before the hyperpolarization of retinal photoreceptors.

Transient retinal phototropism (TRP) has been predominantly observed in rod photoreceptors activated by oblique visible light stimulation. Dynamic confocal microscopy and optical coherence tomography (OCT) have revealed rod outer segment (ROS) movement as the physical source of TRP. However, the physiological source of ROS movement is still not well understood. In this study, concurrent near-infrared imaging of TRP and electroretinogram (ERG) measurement of retinal electrophysiology revealed that ROS movement occurs before the onset of the ERG a-wave, which is known to reflect the hyperpolarization of retinal photoreceptors. Moreover, substitution of normal superfusing medium with low-sodium medium reversibly blocked the photoreceptor ERG a-wave, but largely preserved the stimulus-evoked ROS movements. Our experimental results and theoretical analysis indicate that early, disc-based stages of the phototransduction cascade, which occur before the hyperpolarization of retinal photoreceptors, contribute to the TRP associated ROS movement.

Corneal iontophoresis and cross linking: a preliminary report of our experience.

To evaluate the effect induced by UVA radiation with corneal iontophoresis and cross-linking. From February 2013 to August 2014 we saw 15 eyes of 15 patients, age range 19-38 years (10 women and 5 men) keratoconus stage 1-2. Vision evaluation was carried out with ETDRS scale and Topography and Pachymetry. To evaluate line of demarcation with the confocal microscope and corneal optical coherence tomography (OCT) and the pain with the Faces Pain Scale. At 6 months there was a stabilization of vision and topography, with a slight improvement at 1 year of vision of 1 line and of the Km of 0.5 diopters. The in vivo microscopic examination with the confocal microscope showed that the line of demarcation was not particularly evident, it was irregular and when present was more evident at 150-200 µ depth, there was a keratinocyte activation in the anterior stroma with slight oedema. There were also superficial epithelial alterations present and only slight involvement of the subepithelial nervous plexus, there were no alterations of the endothelium. The Faces Pain Scale the pain score was 2±1. We have to stress the usefulness of Corneal optical coherence tomography (OCT) also pre and post iontophoretic treatment. Further, larger studies and longer follow-ups are needed, recent studies have shown the absorption of riboflavin with iontophoresis is 50% with respect to the classic technique, the percentage of riboflavin in the anterior 2/3 of the corneal stroma would be, however, efficacious to provide good results.