Topic

#Basic Science in Ophthalmology

7 articles

Articles 7 Oct 2021 6 min read

Normal flora /Microbiome of the Eye: 10 Facts

1. Definition of Microbiome Microbiomes are communities of organisms (bacteria, fungi, viruses) that normally reside on any part of the human body (both external and internal) and are in a symbiotic relationship with the host. The members of the microbiome live in close harmony, sharing food and shelter and offering benefits to each other, e.g. some members give protection by secreting extracellular polymeric substances to form a protective covering of biofilm around the community, while some excrete metabolic by-products which are useful substrates for the others. 2. Relation of Microbiome with the host Most of the organisms of the microbiome provide support to the good health of the host (like preventing colonization by harmful pathogens by competing for shelter and food niches, occupying the pathogen receptor sites, or secreting antibiotics and metabolic by-products like acetic and lactic acids which harm such pathogens). But some of the members can also act as opportunistic pathoge

Dr. Sanchita Mitra
Articles 20 Jul 2021 8 min read

Ocular Oncology Basics: Genetics

Twenty first century has seen a giant leap in the understanding of human genetics. Based on the human genome project humans are supposed to have roughly 20,000 to 25,000 genes. Genes are the fundamental units of heredity. To understand genetics involved in various ocular pathologies a basic understanding is essential. The following discussion will provide an overview of basic concepts in genetics and provide a glimpse into the genetics of Retinoblastoma and intraocular melanoma. The basic structure of a chromosome [1] Chromosomes are formed by a tight packaging of the DNA stored in the nucleus of a cell Each gene in humans are comprised of 2 copies ; one inherited from either parent. Forms of the same gene with differences on the basis of bases are known as alleles. A tightly regulated process of transcription and translation involves the production of basic building blocks called as amino acids to form proteins. Gene regulation is the process whereby certain genes are 'switched on' an

Dr. Bikramjit Pal
Articles 1 Jun 2021 10 min read

Ten Microbiological Facts on Mucormycosis All Ophthalmologists Should Know

The present overview highlights major microbiological aspects of mucormycosis and attempts to increase the awareness of this ubiquitous group of fungi that are responsible for the difficult-to-manage infections presently being encountered in the setting of the ongoing COVID-19 pandemic. 1. What is Mucormycosis and why is mucormycosis emerging as a serious threat in the present COVID-19 pandemic? Mucormycosis (previously called zygomycosis; sometimes called black fungus infection) is a serious, but rare fungal infection caused by a group of molds belonging to the order Mucorales(1). Mucormycosis is a fulminant disease with high rates of morbidity and mortality that mainly affects immunocompromised patients. Depending on the location of the infection, the mucormycosis can be rhino-orbito-cerebral (most common), pulmonary, gastrointestinal, cutaneous, or disseminated. Although it has a low incidence rate, varying from 0.005 to 1.7 per million population, a sudden rise in cases of rhino-or

Dr. A.R Anand
Anatomy of eye 2 Apr 2021 12 min read

Anatomy of Conjunctiva

Conjunctiva is a fine, translucent mucous membrane that joins and covers the anterior surface of eyeball and posterior side of the eyelids. It covers the posterior surface of the lids and reflects to cover the anterior part of the sclera, then becomes continuous with the corneal epithelium. At the lid margin conjunctiva is continuous with the skin. The name “conjunctiva” has originated from the term “conjoin” which means “to join” Parts of the conjunctiva: Broadly conjunctiva is divided into palpebral conjunctiva, fornices, and bulbar conjunctiva. Palpebral conjunctiva: It is the part of the conjunctiva that lines the undersurface or posterior surface of the eyelid. Latin word palpebrae mean “an eyelid” The palpebral conjunctiva is again subdivided into marginal conjunctiva, tarsal conjunctiva, and orbital conjunctiva. The marginal conjunctiva is a transitional zone between the skin of the eyelid and the conjunctiva proper. It starts from the intermarginal strips of the eyelid as a con

Dr. Parthopratim Dutta Majumder
Articles 1 Apr 2021 9 min read

Embryology of Eye

Introduction The eyeball development begins early in the 4th week of intrauterine life with formation of optic vesicle (a diverticulum) from diencephalon. The structure of eyeball is shown in Figure 1. Various components of eyeball are derived from the following sources: Retina, iris and optic nerves are derived from optic vesicle that arises from neuroectoderm of diencephalon. Lens and corneal epithelium are derived from lens placode that arises from surface ectoderm. Fibrous and vascular coats of eyeball are derived from mesodermal condensation surrounding the optic vesicle. Choroid and sclera are derived from migrating neural crest cells. Figure 1: Fully developed eyeball Optic Vesicle and Lens Vesicle Formation of optic sulcus: On 22nd day, wall of the diencephalon shows thickening and depression to form optic sulcus. Formation of the optic sulcus or groove is the first indication for development of the eye (Figure 2A). Formation of optic vesicle: Optic sulcus further invaginates l

Dr. Yogesh Sontakke
Anatomy of eye 1 Apr 2021 28 min read

Anatomy of Retina

The retina is the innermost of the three coats of the eye. This layer is responsible for converting relevant information from the image of the external environment into neural impulses that are transmitted to the brain. Broadly retina consists of two primary layers: an inner neurosensory retina and retinal pigment epithelium (RPE). 1 ? Sensory retina develops from the inner layer of the neuroectoderm, whereas RPE is derived from the outer layer of the neuroectoderm. The RPE is continuous anteriorly with the pigment epithelium of the ciliary body. Sensory retina extends from the optic disc to ora serrata, where it is continuous with non-pigmented ciliary epithelium.1 Between the neural retina and RPE, there is a potential space known as subretinal space. The adhesion between neural retina and RPE is relatively weak. The neural retina is firmly attached at its anterior termination, the ora serrata, and at the margins of the optic nerve head. The ora serrata is located 4-6 mm behind cilia

Dr. Parthopratim Dutta Majumder
Interesting Reads 1 Apr 2021 8 min read

Cytokines: Made Simple for the Ophthalmologists

In the time of the global pandemic known as COVID- 19, everyone has heard the phrase ‘cytokine storm’ and how it can be a deadly consequence of the SARS- CoV2 virus infection. What are these cytokines though? What do they normally do in our bodies and why are they sometimes so deadly? Little multifunctional molecules The presence of pus-filled exudates, fever, localized swelling, and pain have been well documented since ancient times. Scientists in the 1940’s asked the question: “What causes all these symptoms?” They studied the pus, found that the white blood cells released ‘soluble factors’1 and the rest, as they say, is history. Structurally, the ‘soluble factors,’ also known as cytokines, are really small proteins (peptides). They are known as cell signaling molecules, as they essentially act as messengers that tell cells what to do. Their general mode of action is quite similar to a domino effect. Cell 1 is stimulated by some external factor and in response it secretes cytokines.

Dr. Swathi Lingam