Applications of Anterior Segment Optical Coherence Tomography in Cornea and Ocular Surface Diseases

Optical coherence tomography (OCT) is a noncontact technology that produces high-resolution cross-sectional images of ocular tissues. Anterior segment OCT (AS-OCT) enables the precise visualization of anterior segment structure; thus, it can be used in various corneal and ocular surface disorders. In this review, the authors will discuss the application of AS-OCT for diagnosis and management of various corneal and ocular surface disorders. Use of AS-OCT for anterior segment surgery and postoperative management will also be discussed. In addition, application of the device for research using human data and animal models will be introduced

Clinical Applications of Anterior Segment Optical Coherence Tomography

Anterior segment optical coherence tomography (AS-OCT) was recently developed and has become a crucial tool in clinical practice. AS-OCT is a noncontact imaging device that provides the detailed structure of the anterior part of the eyes. In this review, the author will discuss the various clinical applications of AS-OCT, such as the normal findings, tear meniscus measurement, ocular surface disease (e.g., pterygium, pinguecula, and scleromalacia), architectural analysis after cataract surgery, post-LASIK keratectasia, Descemet’s membrane detachment, evaluation of corneal graft after keratoplasty, corneal deposits (corneal dystrophies and corneal verticillata), keratitis, anterior segment tumors, and glaucoma evaluation (angle assessment, morphological analysis of the filtering bleb after trabeculectomy, or glaucoma drainage device implantation surgery). The author also presents some interesting cases demonstrated via AS-OCT

In Vivo Confocal Microscopy expanding horizons in corneal imaging

Confocal microscopy is an emerging optical technique that allows the living human cornea to be imaged on a cellular level. As such, confocal microscopy enables morphologic and quantitative analysis of corneal resident cells in health and disease and provides an exciting bridge between in vivo diagnosis and ex vivo histological confirmation of pathologic processes

Use of OCT and Oculus Pentacam HR as Aids to Semi-Scleral Contact Lens Fitting

Purpose: To determine whether semi-scleral contact lenses (sSCL) can be appropriately fitted using corneal sagittal depth measurements, and to determine the impact of fit on visual acuity, effect of time on topographic corneal clearance and comfort ratings. Method: Three sSCL (Jupiter 15mm; Essilor) were fit to 20 subjects who had previous diagnoses of KC (n=18) or PMD (n=2). The fitting of the sSCL were based on the CSD measured with the Visante™ OCT at a 15mm chord on the horizontal meridian. To select the sSCL from the diagnostic trial lens set, values of 325 (lens 1), 375 (lens 2) and 425 (lens 3) μm were randomly added in sequence to the CSD. Subjects were allowed to wear each of the sSCL for 1hour. After this time, the central corneal clearance (CCC) was assessed using an UL-OCT, high contrast visual acuity (HCVA) and low contrast visual acuity (LCVA) were measured using a LogMAR VA chart and comfort ratings were obtained using a comfort rating scale (0-100). Results: The mean CSD in the horizontal meridian was 3.78±0.53 (range: 3.33-4.17) mm at a 15mm chord. The mean CCC was 190±100, 360±120 and 450±170 µm for each lens respectively (p=0.001). The mean CCC loss was 30.00±40.00, 30±60.00 and 40.00±50 µm for each lens respectively (p>0.05). The mean HCVA for lenses 1, 2 and 3 were 0.05±0.12, 0.07±0.11 and 0.11±0.08 respectively, which were significantly different (p=0.02). Tukey post hoc analysis demonstrated that this difference was only significant between lenses 1 and 3 (p=0.01). Similar findings were found for LCVA. The overall comfort rating for all three sSCL was 77.7±10.6. The comfort ratings for lenses 1, 2 and 3 were 74.9±9.2, 79.7 ±11.6 and 78.6±10.8 respectively. These differences were not significantly different (p=0.24). Conclusion: Evaluation of CSD can be used effectively to select which sSCL to fit on the eye. The results of this study suggest that lens 2 (adding 375 μm to the CSD) gave the best combination of VA and comfort ratings. However, evaluation of the fluorescein pattern must be balanced with the VA and comfort ratings for successful fitting of sSCL in a clinical setting. There was also a likelihood of topographic corneal loss after 1 hour of sSCL wear; however, this may vary depending on many factors such as scleral zone and its relationship with the scleral conjunctiva. Eyelid force, design of the contact lens and other unknown factors may play a part in the contact lens settling time and amount

Clinical Phenotypes and Cellular Mediators in Diabetic Retinopathy

The aim of this work was to establish meaningful clinical end-points and surrogate markers for diabetic macular ischaemia, a condition for which there is no treatment. The relationship between diabetic eye disease and circulating cellular mediators of angiogenesis and inflammation was further explored with a view to developing therapy in the longer term. Visual loss in diabetic macular ischaemia was observed to occur only in moderate to severe disease, progresses at a rate of 5-10% increase in area per year and associated with thinning of the retinal nerve fibre layer. Direct visualisation of cells in the vitreous was achieved using optical coherence tomography. Novel methods for this were further developed in inflammatory eye disease, with a view for application in diabetic eye disease. A method for in vivo labelling of cells using ICG to enhance visualisation was described. In the field of regenerative medicine, this technique may allow direct visualisation of cell-mediated inflammation regardless of the type of cell or tissue transplanted. EPC and monocyte profiles were analysed in the context of diabetic eye disease. Elevated levels of EPCs as defined by CD34+ CD309+ were observed in diabetes, but no associations were observed with progression. There were no initial associations between monocyte subsets and diabetic eye disease severity at the outset but differences were observed in the context of progression. Observations from this work support the notion that inflammation plays an important role in diabetic eye disease and will inform development of new treatments in this field

Clinical Phenotypes and Cellular Mediators in Diabetic Retinopathy

The aim of this work was to establish meaningful clinical end-points and surrogate markers for diabetic macular ischaemia, a condition for which there is no treatment. The relationship between diabetic eye disease and circulating cellular mediators of angiogenesis and inflammation was further explored with a view to developing therapy in the longer term. Visual loss in diabetic macular ischaemia was observed to occur only in moderate to severe disease, progresses at a rate of 5-10% increase in area per year and associated with thinning of the retinal nerve fibre layer. Direct visualisation of cells in the vitreous was achieved using optical coherence tomography. Novel methods for this were further developed in inflammatory eye disease, with a view for application in diabetic eye disease. A method for in vivo labelling of cells using ICG to enhance visualisation was described. In the field of regenerative medicine, this technique may allow direct visualisation of cell-mediated inflammation regardless of the type of cell or tissue transplanted. EPC and monocyte profiles were analysed in the context of diabetic eye disease. Elevated levels of EPCs as defined by CD34+ CD309+ were observed in diabetes, but no associations were observed with progression. There were no initial associations between monocyte subsets and diabetic eye disease severity at the outset but differences were observed in the context of progression. Observations from this work support the notion that inflammation plays an important role in diabetic eye disease and will inform development of new treatments in this field

Advances in Ophthalmology

This book focuses on the different aspects of ophthalmology - the medical science of diagnosis and treatment of eye disorders. Ophthalmology is divided into various clinical subspecialties, such as cornea, cataract, glaucoma, uveitis, retina, neuro-ophthalmology, pediatric ophthalmology, oncology, pathology, and oculoplastics. This book incorporates new developments as well as future perspectives in ophthalmology and is a balanced product between covering a wide range of diseases and expedited publication. It is intended to be the appetizer for other books to follow. Ophthalmologists, researchers, specialists, trainees, and general practitioners with an interest in ophthalmology will find this book interesting and useful

Functional outcome of retinal oedema and its standard treatment

Macular oedema is a pathological condition of fluid accumulation in the retinal tissues. It is a nonspecific sign of several retinal diseases that in the long term can lead to permanent vision loss. The clinical aspect of macular oedema treatment and vision recovery is reduction of the amount of fluid accumulated in the retina. Due to its complex pathophysiological mechanism, macular oedema has proven challenging to manage. Many unanswered questions remain in the ophthalmology world on this subject. The development of recent diagnostic tools such as optical coherence tomography allows better understanding of the morphological changes in the retina. Now we are able to detect retinal oedema and characterise it by location, depth, and amount of fluid. Further, clinicians are now able to assess therapeutic response by examining the anatomical structures of the retina. Yet, with techniques offering objective accuracy, emerging reports have shown discrepancies between clinically examined visual acuity, anatomical changes of the retina, and patients’ self-reported visual ability. The presence of such discrepancies is also supported by the fact that results achieved by randomised clinical trials rarely align with results attained in real-world settings. Today, functional vision testing can be performed with several different methods including questionnaires, colour vision tests, reading speed tests, contrast sensitivity tests etc. Nevertheless, none of these methods are widely used in clinical settings, and their predictive capabilities have yet to be explored. Establishing precise methodology for functional vision testing is likely to provide better understanding of patients’ treatment response. This thesis aims to investigate the potential predictive capabilities of functional vision tests and to compare these capabilities with those of well-established, routine ophthalmic examinations such as visual acuity and retinal thickness tests. In the current research, I focused on the following functional examinations: the visual function questionnaire (VFQ- 25), reading speed testing, and testing of the contrast sensitivity of the macula area (examined by microperimetry). These techniques allowed very specific and sensitive testing of the functionality of the retina. In addition, I explored functional vision tests and their association to the routine ophthalmic tests and their ability to detect sub-clinical changes in vision. I believe further research in this area will offer better understanding of the functional vision changes in patients with macular oedema and potentially will help in improving visionrelated quality of life

Clamp-assisted retractor advancement for lower eyelid involutional entropion

Scientific Poster 144PURPOSE: To describe a novel approach to internal repair of lower lid entropion using the Putterman clamp. METHODS: Retrospective, consecutive case series of patients with entropion who underwent retractor advancement using the clamp. RESULTS: Seven eyes of 6 patients (average age: 80; 4 women and 2 men) were analyzed. Complete resolution was achieved in 5 of the 6 patients (83.3%). The 1 patient with recurrence had 2 previous entropion surgeries on each eye over the past 4 years; there was lid laxity, and horizontal tightening was needed. No severe adverse events occurred in the patients. CONCLUSION: Clamp-assisted lower lid retractor advancement offers a safe and effective, minimally invasive approach to involutional entropion. Further study is needed to assess its role in recurrent entropion.postprin