Retina & Vitreous

51–60 of 72 articles Page 6 of 8

All Cornea 36 Cataract 17 Glaucoma 14 Retina & Vitreous 72 Neurophthalmology 8 Oculoplasty 15 Uvea & Inflammatory Diseases 24 Miscellaneous 20 Oncology 9 Pediatric Ophthalmology 16

19 min read

A (VAST)IN Saga

Vascular endothelial growth factor (VEGF)-A is a key mediator of angiogenesis. The discovery of VEGF-A, like many other major discoveries in medicine, happened partly by observations and partly by chance. Napoleone Ferrara and his team were working on a population of non-hormone-secreting cells from the anterior pituitary of cows. (1) One day Ferrara mixed some isolates from cultures of follicular cells with endothelial cells. Ferrara was surprised to see the rapidly proliferating endothelial cells started rapidly. Ferrara understood that the pituitary cells were secreting an angiogenic protein. With this observation, Ferrara worked on the isolation and cloning of this angiogenic protein. In 1989, Napoleone Ferrara and Hazel at Genentech laboratory were the first to isolate and clone vascular endothelial growth factor (VEGF). Ferrara recalls, “I worked on the isolation of VEGF in my spare time during my first six months to a year at Genentech. Once we cloned VEGF in 1989, the company b

Dr. Bikramjit Pal · Dr. Parthopratim Dutta Majumder
10 min read

Binocular Indirect Ophthalmoscopy : The Beginner's Guide

The technique of examining the fundus of the eye is called ophthalmoscopy. In direct ophthalmoscopy, a virtual and erect image of the fundus is seen. In indirect ophthalmoscopy, a real and inverted image is formed between the condensing lens and the observer. The advantage of stereopsis (depth perception) and a larger field of view makes indirect ophthalmoscope (IDO) more useful both in retina clinics and during posterior segment surgeries. Inventions and innovations The journey of developing ophthalmoscopy began with an idea by the great physicist, Hermann von Helmholtz, who described the optical principles of direct ophthalmoscopy in 1851 (Fig:1a). This was followed by series of innovations and methods of examination including the indirect method of ophthalmoscopy developed by Reute in 1852 (Fig:1b), binocular model by Marc-Antoine Giraud-Teulon (Fig:1c) and more practical hand-held reflex-free binocular ophthalmoscope by Allvar Gullstrand (Fig:1d). It was Charles Schepens who popula

Dr. Nagesha CK
4 min read

Ten Tips for Managing a Case of Postoperative Endophthalmitis

1. Suspect : Any unusual post-operative reaction ( out of proportion to surgical trauma ) should be suspected for Endophthalmitis. 2. Differentiate from TASS : All unusual post-operative reactions may not be infective; Pointers towards Toxic Anterior Segment Syndrome could include: Early onset of Limbus to limbus corneal edema with good fundus glow and no exudates in the vitreous cavity. The presence of Lid edema, chemosis, a marked reduction in vision, vitreous exudates, and low intraocular pressure should alert one for Infective Endophthalmitis. 3. Talk : The most difficult part is how to tell the patient about this. This is a very sensitive issue because in Today`s time, no patient is willing to take any negative news ( Thanks to Trivilisation of eye surgery / googlisation etc.) and there is always a potential for medicolegal issues cropping up. Talking requires some degree of compassion. It is advisable to take a picture of the anterior segment & fundus, even if hazy. Take patient

Dr. Lalit Verma
11 min read

ILM Peeling Simplified - Ten Tips for the Beginners

1 How to choose the right cases to start Idiopathic macular hole in non-myopic eye is a good case. ILM comes off as a single sheet and underlying retina is healthy. Same applies to traumatic macular holes. Beginners can also start peeling ILM in eyes with epiretinal membrane. Unsuccessful peeling may not jeopardize the long-term outcome significantly here. Peeling ILM for Myopic macular holes or in eyes with Diabetic Retinopathy needs more experience but can be achieved easily if one understands the basics of peeling. 2 Arrange your Inventory – Forceps is the key Lander's ring with Macular contact lens, Disposable ILM forceps and BBG dye serve as a formidable low-cost inventory for ILM peeling. A good ILM forceps should match your technique of ILM peeling. Because most of us initiate peel by "Pinch Technique", forcep is desired to have a structure that can "pinch". It needs to have fine teeth on opposing surfaces and good range of movement for its prongs. It should also be light weight

Dr. Deependra V Singh · Prof. (Dr.) Yog Raj Sharma
17 min read

Learn from the Masters : Tips and Tricks of Vitreoretinal Surgery

“If you are brave enough to start the right way, you will be strong enough to finish at the right place.” The most crucial aspect of vitreoretinal surgery is learning it the right way. And if you have the guidance of teachers with experiences of a lifetime, there is an abundant pool of knowledge you can extract. Plenty of young VR surgeons are facing difficulties in the basic principles and doctrines of surgery. Some of these basic questions were compiled together and addressed to the top-notch VR surgeons of India, owing to a simple and lucid explanation for the same. Dr. Atul Kumar, MD, FAMS, FRCS(Ed) is the Chief & Professor of Ophthalmology at Dr. R.P. Centre, AIIMS, New Delhi since 1st January 2016. He completed MD & Sr. Residency from Dr. R.P. Centre, AIIMS New Delhi India & joined as Assistant Professor in the same institute in 1987 (Discipline: -Vitreous-Retina). He pursued Retina Fellowship from the University of Maryland, Baltimore, USA, 1990. He has 313 indexed & non-indexed

Dr. Dhaivat Shah
5 min read

Ten Tenets of Fundus Autofluorescence

1. What is fundus autofluorescence? Fundus autofluorescence is a study of the topographic distribution of naturally occurring molecules in the human fundus. These molecules are called fluorophores. In principle, FAF is similar to fundus fluorescein angiography as both of them study the fluorescence pattern of molecules. However, the fluorophore molecules are naturally occurring compounds in the former while in later sodium fluorescein dye is injected. Hence FAF is a non-invasive imaging modality. 2. What are fluorophores? Fluorophores are molecules that emit fluorescence when excited by a suitable wavelength of light. Fluorophores are not exclusively present in the fundus and are distributed in various ocular tissue which includes the cornea, lens, uvea melanocyte, retinal pigment epithelium (RPE), and sclera.1,2 The knowledge about fluorophores other than fundus is still evolving. The commonly studied fundus fluorophores lipofuscin and melanin. 3. Lipofuscin and melanin Lipofuscin is

Dr. Kumar Saurabh · Dr. Suraj Mistry
8 min read

Slit-lamp Biomicroscopy

A slit-lamp is a binocular microscope used for eye examination using a slit-like light beam. In 1911, Allvar Gullstrand a Swedish Ophthalmologist designed table-mounted binocular eyepiece for 3-dimensional visualization of optically clear eye structures. Later Otto Henker, combined Gullstrand slit lamp with Czapski’s binocular microscope resulting in first slit lamp biomicroscope, allowing hand-free examination of an eye.1 The optical design of the Slit-Lamp Biomicroscope (SLB). Due to the miniature size of the anterior segment of the eye, we need high magnification and clarity to appreciate finer details. This can be achieved by having 2 convex lenses at the observer end (eyepiece) separated at its focal distance (astronomical telescope type alignment) and, a concave-convex combination (Galilean telescope type alignment) at the examinee’s end for further magnification of the image. Telescopic arrangements of lenses need to be focused at near, hence a plus power objective lens is fixed

Dr. Nagesha C K · Dr. Shruthi M N
5 min read

Ten Pearls for Performing Vitrectomy in Diabetic Retinopathy

Important terms: Truncation: To relieve all the surrounding traction 360 degree Segmentation: Dividing a larger membranes/FVP into smaller islands of FVP by 360-degree truncation around them. Delamination: Separation of these membranes/FVP from the retinal surface to which they are firmly adherent by creating a plane of dissection between them. Pearl #1 When not to perform vitrectomy in diabetic retinopathy? Answer: In cases of extramacular tractional retinal detachment (TRD) when the fovea is attached and the patient has a comparative good vision the extramacular TRD can be observed. Charles and Flinn reported only 21% of extramacular TRD extending into macula without any surgical intervention. Also, DRVS (Diabetic retinopathy vitrectomy study) reports that only 23% of eyes with TRD developed severe visual loss at 2 years. Also, early intervention in such extramacular TRD’s can sometimes lead to more harm than benefit owing to the surgery itself. Pearl #2 First step should always be c

Dr. Raja Narayan
43 min read

Visual Electrophysiology Made Simple for the Postgraduates

Visual electrophysiology is an extremely useful tool to study the retinal function objectively. It assesses the functional aspects of not only the retina but also the visual pathway as a whole. Even in this era of advanced imaging, one cannot ignore the importance of the functional aspects of the cellular network in the retina. The commonly used tests with their salient applications are enumerated in Table 1. S.no Test Application 1. Electroretinogram(ERG) Elicits mass response from the Retina 2. Electro-oculogram(EOG) Assesses the function of the Retinal pigment epithelium 3. Pattern ERG(PERG) Differentiates macular and optic nerve pathology 4. Multifocal ERG(MfERG) Picks up focal retinal pathology and maps out the topography 5. Photopic Negative Response(PhNR) Tests the function of retinal ganglion cells 6. Visual Evoked Potentials(VEP) Assesses the visual pathway up to the occipital cortex 7. Multifocal VEP(MfVEP) Picks up focal dysfunction of the visual pathway and maps the topogra

Dr. Parveen Sen · Karthika Pandurangan · +1 other
30 min read

Clinical Applications of Multicolor Imaging

Multicolor imaging (MCI) is a non-invasive retinal imaging modality available in the Spectralis platform (Heidelberg Engineering, Heidelberg, Germany). It simultaneously acquires three reflectance images of the retina using three individual lasers of different wavelengths: blue (488 nm), green (515 nm), and infrared (820 nm). These penetrate the tissue to different depths, simultaneously capturing and depicting information originating from different retinal structures. The infrared reflectance (IR) image visualizes structures at the level of the outer retina and choroid. The green reflectance (GR) image allows imaging of retinal blood vessels, hemorrhages, and exudates. The blue reflectance (BR) particularly provides details of the inner retina and the vitreoretinal interface such as epiretinal membranes, retinal nerve fiber layer (RNFL) thinning, and macular pigment changes. The information from these three images is integrated to form a composite multicolor image.1 Color fundus photo

Dr. Sugandha Goel · Dr. Rupak Roy