Articles

131–140 of 232 articles Page 14 of 24
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
  1. 1 Apr 2021 7 min read

    Refraction Simplified for the Post Graduates

    The optics of the eye normally creates a clear image by refracting rays of light to focus on the retina. Imperfections in this optical system create aberrations and thus blurred images. The goal is to analyze them and devise a means to eliminate them. Lower order aberrations are primarily refractive errors when parallel rays of light after refracting, do not focus on the retina with accommodation at rest. 1. Retinoscopy It is the objective method of detecting refractive errors by a method of neutralization. Point focus formed at a far point of the eye according to its refractive status. For e.g. In a patient with 1 dioptre of myopia, the far point is at 1 meter. For easy mathematical calculations, 1metre is used for retinoscopy. But practically, 66cm is preferred as it is easier to perform retinoscopy at an arm’s length (which is 66cm). The two principal meridia are recognized and power is determined by neutralization. Usually the two meridia are 90 degrees and 180 deg. In cases of obl

    Dr. R Krishna Prasad · Dr. Sayali D Mahajan
  2. 1 Apr 2021 41 min read

    Fungal Keratitis: A Review for the Post-Graduates

    Introduction Fungal or mycotic keratitis is a leading cause of ocular morbidity, opacification and preventable blindness.1 The approximate annual incidence of fungal keratitis in India is said to be 11.3/10,000 population.2 Frequently it is caused by filamentous fungi (Aspergillus, Fusarium, Curvularia) in the tropical areas, while in temperate regions it is predominantly caused by Candida species (C. albicans, C. Parapsilosis). It is considered as one of the most difficult forms of microbial keratitis for the Ophthalmologist to diagnose and manage. Medical therapy alone is often inadequate and surgical therapy like therapeutic penetrating keratoplasty, conjunctival flap, lamellar keratoplasty or cryotherapy is required for control of infection. Epidemiology and Demographics Fungal keratitis incidence or prevalence is more in tropical regions of the world like India and Southern USA and is less commonly encountered in the temperate zones.3 In East India, fungal keratitis was found to b

    Dr. Ankit Anil Harwani · Dr. Meena Lakshmipathy
  3. 1 Apr 2021 11 min read

    How do we treat inflammatory CNVM ?

    Inflammatory choroidal neovascular membranes (CNVM) cause an acute and significant visual loss 1,2. Mostly affecting eyes with posterior or panuveitis, the chronic recurrent nature of inflammation further worsens the visual prognosis in these eyes, such as serpiginous like choroiditis, punctuate inner choroidopathy (PIC), multifocal choroiditis, Vogt-Koyanagi-Harada (VKH) disease, presumed ocular histoplasmosis syndrome, toxoplasma retinochoroiditis, etc,.3,4 . The angiogenic stimulus in inflammatory CNVM is driven by local inflammation and/or a degenerative breach in retinal pigment epithelium (RPE)-Bruch’s membrane complex4. An active intraocular inflammation induces the release of several inflammatory mediators including cytokines, chemokines, vascular endothelial growth factor (VEGF) and complement activation, which in turn promote retinal and choroidal neovascularization. Majority of inflammatory CNVM are classic (on fundus fluorescein angiography), and type 2 on spectral domain o

    Dr. Krinjeela Bazgain · Dr. Nitin Kumar · +1 other
  4. 1 Apr 2021 13 min read

    Duanes Retraction Syndrome Made Ridiculously Simple

    Synonyms: Stilling–Turk–Duane syndrome. Duane Retraction Syndrome is a type of congenital cranial dysinnervation which occurs in 1-4% of strabismus cases. It has varied presentation mostly involving variable horizontal duction deficits, with narrowing of the palpebral fissure and globe retraction on attempted adduction, occasionally accompanied by upshoot or down shoots Etiopathogenesis Various theories have been proposed earlier for the cause of DRS but currently, the most accepted theory is that of innervational anomalies which leads to all the features of DRS. It is considered to be a part of congenital cranial dysinnervation syndrome as it’s a developmental anomaly of the 6th cranial nerve or its nucleus leading to innervational deficiency of lateral rectus muscle which might be associated with secondary innervational abnormality with Medial rectus. The lack of normal innervations of lateral rectus was proved by electromyographic studies. It is also associated with paradoxical inne

    Dr. Prerana Tripathi, DO, DNB, FICO · Dr. Sowmya R, MS,FMRF, FAICO
  5. 1 Apr 2021 10 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
  6. 1 Apr 2021 7 min read

    Panophthalmitis: A Ready Reckoner for Postgraduates

    Introduction Panophthalmitis is a severe ocular and orbital condition which can lead to phthisis bulbi or may necessitate evisceration. Severe inflammation of the anterior and posterior segments is frequently accompanied by microbial keratitis, necrotizing scleritis, and perforation or rupture following trauma. The disease develops rapidly and the prognosis is poor. The management of patients with intractable panophthalmitis remains challenging with eye salvage almost impossible in most cases. Etiology and Pathogenesis Panophthalmitis is a purulent inflammation of all coats of the eyeball including intraocular structures. Although post-traumatic endophthalmitis is the most common preceding event, the infection can result after postoperative endophthalmitis following cataract surgery, keratoplasty, or rarely after posterior segment procedures. It can also be caused by septicemia or can spread from a pus-producing infection in another part of the body. [Table 1] Organisms implicated incl

    Dr. Namrata Adulkar
  7. 1 Apr 2021 8 min read

    Ten Pearls for Multifocal IOL

    1. Science behind Multifocal Intraocular Lens (MFIOL) Multifocal intraocular lenses are IOLs which can separate incoming light into two or more foci, thus resulting in multiple coexisting retinal images. At any given point, only one of the images (distance, intermediate or near) is the sharpest, and hence selected by the brain for visualisation. This concept is known as simultaneous vision. The visual system in any mammal is not known to be multifocal, hence the implantation of these IOLs initiate a process of neuroadaptation in the recipient’s brain, and its best effect is seen only after some days to weeks. The splitting of light to form multiple images leads to loss of contrast for each image. However, despite these limitations, MFIOLs continue to be one of the best technologies to provide spectacle independence for all distances after cataract surgery. 2. Types of MFIOL MFIOL can be classified in two ways: Based on focality or the number of foci or images created by the lens: Tradi

    Dr. Partha Biswas · Dr. Sneha Batra
  8. 1 Apr 2021 19 min read

    Angioid Streaks

    Angioid streaks are visible irregular crack-like dehiscences in Bruch’s membrane that are associated with atrophic degeneration of the overlying retinal pigmented epithelium. Despite 50 % of cases being idiopathic, this condition grabs attention as it requires good history taking and workup to determine the cause. Historical background The first description of angioid streaks was provided in 1889 by Dr. Robert W. Doyne, an English ophthalmologist. He noticed irregular, jagged deeply pigmented lines especially around the discs of both eyes in a patient who sustained trauma in both eyes and attributed it to be due to the rupture of pigment layer of retina. [1] Because of their resemblance to blood vessels, Herman J. Knapp, a German-born American ophthalmologist coined and introduced the term "angioid streaks" in 1892. [2] They are also known as Knapp’s striae. Clinical examination with histopathological findings by Bock in 1938 in two patients with pseudoxanthoma elasticum confirmed that

    Dr. Remya Paulose · Dr. Bhavik Panchal · +1 other
  9. 1 Apr 2021 16 min read

    Paediatric Retinal Vascular Diseases

    Introduction This chapter will discuss pediatric retinal vascular diseases like Persistent Fetal Vasculature, Familial Exudative Vitreo Retinopathy and Incontinentia Pigmenti Persistent Fetal Vasculature (Persistent Hyperplastic Primary Vitreous) Definition Persistent hyperplastic primary vitreous (PHPV) is a congenital ocular disorder in which fetal vasculature does not regress after birth. It is unilateral approximately 90% of the time. No single gene has been identified. It can vary from very subtle with no visual disturbance to as severe as phthisis bulbi or secondary glaucoma. The prognosis can be good if early intervention is planned. Due to its wide spectrum of presentation, it has now been renamed as persistent fetal vasculature (PFV).1 Pathogenesis 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

    Parag K. Shah, DNB · Dr. V. R. Saravanan · +1 other
  10. 1 Apr 2021 13 min read

    Tips on Management of Intraocular Foreign Body

    Introduction Open globe injuries (OGI) are associated with retained intraocular foreign body (IOFB)in 18 to 41% of cases1. Retained IOFB is an important cause of visual morbidity and blindness, especially in working-age population with male predominance. Majority of the IOFBs are related to trauma at workplace1. Types of IOFB Majority of IOFB are metallic1,2. It is followed by organic IOFB and metallic non magnetic IOFB. Metallic IOFB like iron or copper can cause metallosis leading to poorer visual outcomes if left untreated. Organic IOFB are associated with high incidence of fungal endophthalmitis and need treatment on emergency basis. Inert IOFB like glass or noble metal like gold can be present in a minority of patients. Theoretically these can be managed conservatively, however with advancements in Vitreoretinal Surgery it is seldom done. Location of IOFB Most common resting place for IOFB is vitreous cavity. Though it may be lodged in any part of the eye. IOFB might be present in

    Dr. Maneesh Bapaye