Retina & Vitreous

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All Cornea 36 Cataract 17 Glaucoma 13 Retina & Vitreous 72 Neurophthalmology 8 Oculoplasty 15 Uvea & Inflammatory Diseases 24 Miscellaneous 20 Oncology 9 Pediatric Ophthalmology 15

12 Apr 2021 28 min read

Choroidal Neovascular Membrane: Made Easy For Postgraduates

Introduction Choroidal neovascularization (CNV) or choroidal neovascular membrane (CNVM) is a growth of new choroidal vessels into the subretinal space through breaks in the Bruch's membrane. Ophthalmoscopically the CNVM appears as a greenish-grey lesion, often with a detachment of the sensory retina, subretinal blood, and exudates. Choroidal neovascularization can be multifactorial with the commonest being due to age-related macular degeneration (AMD), called the wet or exudative AMD. The other causes of include high myopia, angioid streaks, presumed ocular histoplasmosis syndrome, choroidal rupture post-trauma, osteoma, macular telangiectasia, inflammatory and idiopathic. Since the most common cause of CNVM remains age-related, this writeup will focus on the same. Age-related macular degeneration is the most common cause of blindness in the western world over the age of 65 years. With a worldwide UN estimate of about 20-25million, 8 million individuals are in the USA alone.1 The numb

Dr. Santosh Gopi Krishna Gadde · Dr. Nikitha Reddy Gurram · +1 other
2 Apr 2021 5 min read

Intravitreal Injections -technique and tips

Intravitreal injections involve injecting therapeutic agents (drugs/air/gases) inside the vitreous cavity through pars plana under aseptic precautions Surgical anatomy Site of injection: Pars plana Ciliary body: Consists of two parts a) anterior pars plicata b) posterior pars plana Pars plicata Circumferential zone 2.5mm in anteroposterior diameter Pars plana Varies in anteroposterior diameter nasally 3mm wide and temporally 4.5mm wide. This variation is because of the posterior globe on temporal side curves posteriorly & laterally more than on the nasal side. Pars plana extend from pars plicata anteriorly to ora serrata (termination of the retina) posteriorly. Blood vessels in pars plana are radially oriented but circumferential incisions across these vessels cause no bleeding. Also, lens zonules insert into ciliary body avoiding pars plana Thus, needle punctures 3.5 mm posterior to limbus enter globe through pars plana Not damaging lens Not puncturing the retina Not tethering / damag

Parag K. Shah, DNB · Dr. Varsha V. Prabhu
2 Apr 2021 15 min read

Advances in Retinal Imaging

Modern imaging modalities in the field of the retina have expanded our understanding of common pathologies including diabetic retinopathy (DR), age-related macular degeneration (AMD), central serous chorioretinopathy (CSCR), and many rare retinal diseases such as dystrophies, which were poorly understood before. This chapter describes newer emerging techniques in retinal imaging which enables advanced screening, monitoring and provide objective measures for treatment monitoring. MULTICOLOUR IMAGING Compared to standard fundus cameras, multi-colour images produced by the scanning laser ophthalmoscope(SLO) have a higher resolution due to reduced light scatter and allow image acquisition at different planes and higher contrast through a non mydriatic pupil using different wavelengths. SPECTRALIS Optical Coherence Tomography SDOCT(SPECTRALIS SD-OCT, Heidelberg Engineering,Heidelberg, Germany) uses the confocal scanning laser ophthalmoscope(cSLO) to capture three simultaneous reflectance im

Dr. Sushma J · Dr. Jay Chhablani
2 Apr 2021 12 min read

Lattice degeneration of the retina

Lattice degeneration is a vitreoretinal degenerative process of the peripheral retina with visible lesions that predispose to retinal tears and detachment. Vitreous traction at sites of significant vitreoretinal adhesion is responsible for most retinal breaks that lead to retinal detachment. GOALS of identifying the patients with risk of RD are: Identify patients at risk of RRD Examine patients with symptoms of acute PVD to detect and treat significant retinal breaks Manage patients at high risk of developing retinal detachment Educate high-risk patients about symptoms of PVD, retinal breaks, and retinal detachments and about the need for periodic follow-up. Natural history of precursors to rhegmatogenous retinal detachment Precursors to retinal detachments are PVD, symptomatic retinal breaks, asymptomatic retinal breaks, lattice degeneration, and cystic and zonular traction retinal tufts. Because spontaneous reattachment is exceedingly rare, nearly all patients with asymptomatic RRD w

Dr. Manoj Khatri
2 Apr 2021 11 min read

Persistent Fetal Vasculature Syndrome

It is a congenital ocular disorder where fetal vasculature persists. It can be either subtle (no disturbance in vision) or severe (profound visual loss) Anatomy The fetal vasculature is composed of two parts: Tunica vasculosa lentis: It is situated anteriorly encircling the lens. It has anterior and posterior divisions. Anterior division has additional attachments to the pupillary frill of the iris. Posterior division has additional attachments to the ciliary process and continues with the hyaloid artery posteriorly. Hyaloid artery: It is situated porteriorly behind the lens. It is also called primary vitreous. The hyaloid vessel extends from posterior surface of lens to the disc. The vasculature fills the vitreous cavity & has many attachments to the retinal surface Normal regression of embryonic vascular system1 During development blood flow to the eye is through hyaloid artery. At the 240-mm stage (seventh month), blood flow in the hyaloid artery ceases. Hyaloid vascular regressio

Parag K. Shah, DNB
2 Apr 2021 14 min read

Retinopathy of Prematurity

Introduction Retinopathy of Prematurity (ROP) is a fibrovascular proliferative disorder, which affects the developing peripheral retinal vasculature of premature infants. It is an avoidable cause of blindness in children. The initial signs of ROP are detectable by a few weeks after birth, and the condition progresses rapidly thereafter. This means that screening has to be timely, and there is only a very narrow window of opportunity for treating. If not treated, the condition progresses rapidly to Stage 4 or 5 in approximately 50% of babies. The visual prognosis for babies with Stage 5 disease (total retinal detachment) is very poor, even after complex vitreoretinal surgery. The primary goal of screening is to detect all babies with treatable disease in time for treatment to be effective. Pathogenesis In the normal foetus, vascular development of the retina occurs in two phases. Phase 1 (True vasculogenesis): It occurs from 8-21 weeks of foetal development. Spindle cells (mesenchymal p

Parag K. Shah, DNB · Dr. V. Narendran, DNB · +1 other
2 Apr 2021 10 min read

Pan Retinal Photocoagulation (PRP), Focal Laser & Photodynamic Therapy (PDT) Technique & Tips.

Introduction ‘LASER’ is acronym for “Light Amplification by Stimulated Emission Radiation.” This describes the emission process by which an intense beam of electromagnetic radiation is generated Basic Properties of Laser Always monochromatic (one wavelength) Collimated (all photons run parallel) & focused to a small point Coherent (always in same phase) Highest possible speed Physics Certain substances have property to lase i.e, absorb energy in one form & emit a new form of energy. On pumping these lasing substances electrons are transfered from a lower orbit to higher orbit (Bohr’s theory) Excited atoms in turn decay back to their original orbit of lower energy, emitting photons (packets of energy) This emission can be spontaneous or induced (stimulated) Photocoagulation (PHC) Photothermal reaction Temperature elevation 10 to 20 deg C Protein denaturation Pigment dependent Argon, krypton dye, diode, frequency double Nd Yag Tissue effects Induces moderate sterile inflammation- Creates

Parag K. Shah, DNB · Dr. Varsha V. Prabhu · +1 other
2 Apr 2021 38 min read

Idiopathic Macular Hole

Introduction Recent advances in the pathogenesis, classification, and surgical intervention of idiopathic macular holes have generated a renewed interest in this entity. Better indicators of the visual outcome, as well as refinements in the surgical technique, have led to improvements in the success of macular hole surgery. Clinical characterization and theories on the pathogenesis of macular hole have continued to evolve. Although originally thought to be the result of trauma, it is now recognized that most macular holes occur in the absence of antecedent injury and are referred to as idiopathic. Theories for the pathogenesis of idiopathic macular holes have included progressive thinning of the foveal tissue and pre hole cyst formation. The primary pathogenic role of the vitreous was suggested by studies that indicated a low relative risk for macular hole formation in eyes with complete posterior vitreous detachment. Gass proposed a theory whereby shrinkage of adherent cortical vitreo

Sandeep Saxena, M.S., MAMS
2 Apr 2021 60 min read

Retinal vein occlusion

Introduction Retinal vein occlusion (RVO) is the second most common retinal vascular disease to cause visual loss in adults after diabetic retinopathy. RVO has been classified into two main types, namely Central retinal vein occlusion (CRVO), Branch retinal vein occlusion (BRVO), the latter being more prevalent. Hemi-retinal vein occlusion has been classified separately since pathogenetically they are different as compared to the above two groups. In the following chapter a brief introduction to these variants of RVO, along with their epidemiology, clinicopathological profile, and treatment has been discussed. Epidemiology [1] The most recently published study summarizing 68,751 individuals from 15 studies, quoted that the prevalence of RVO was 5.20 per 1000 (for any form of RVO). The prevalence of BRVO alone was 4.42 per 1000 (95% CI 3.65–5.19) and that of CRVO was 0.80 per 1000. According to Hayreh et al, prevalence varied by ethnicity and increased with age, but do not differ by gen

Dr. P. Mahesh Shanmugam, MBBS, DO, FRCSEd, PhD, FAICO · Divyansh Mishra · +1 other
2 Apr 2021 13 min read

Perfluorocarbons in Ophthalmology

INTRODUCTION Perfluorocarbon liquids (PFCLs) were first developed in 1970s as possible substitutes to erythrocytes[1],[2] because of their capacity to dissolve relatively large amounts of oxygen. Initial trials with these compounds focused on their feasibility to be used as blood substitutes. These experiments proved the biocompatibility of these compounds. Based on their properties, they were then introduced for intraocular use, in what has become a milestone in vitreoretinal surgery. After animal studies confirmed the safety of PFCL compounds as vitreous substitutes, Chang et al in 1987 first described the successful intraocular use of low viscosity liquid fluorocarbons (perfluorotributylamine and perfluorodecalin) in four patients with complicated retinal detachments.[3],[4] Long-term tamponade in animal models demonstrated retinal atrophy and retinal necrosis at the perfluorocarbon aqueous interface after 4 weeks even when highly purified PFCL compounds (perfluorodecalin) were used

Dr. Abhishek R. Kothari