Eye conditions: Retinal disorders: Pathology review

2,968views

00:00 / 00:00

Preguntas

Preguntas del estilo USMLE Step 1

de completadas

A 17-year-old girl is brought to the ophthalmology clinic due to progressively worsening vision over the past several months. The patient states that she has difficulty driving--particularly at dusk and at night. Her mother states the patient has seemed “clumsier”, often running into tables and cabinets. The patient is otherwise healthy.  Vitals are within normal limits. Bilateral corneas appear unremarkable. Pupils are equal and reactive to light. The red reflex is present bilaterally. Visual field testing demonstrates mild loss of peripheral visual fields. Which of the following ophthalmologic structures reflects the primary site of pathology for this patient’s condition?  


Transcript

Watch video only

At the ophthalmology clinic, 71-year-old Zoe comes in. She says that about 4 hours ago, she experienced a sudden flash of light followed by many floaters in her right eye. Her visual disturbances have since progressed to a peripheral loss of vision, and it’s spreading to the rest of her visual field. Next to her, an 8-month-old male infant named Nirban, is brought in by his father, who is worried because he noticed that Nirban’s eyes appear white in their family pictures. Ophthalmologic examination reveals the absence of red reflex on both eyes. On further questioning, the father tells you that as a child, he had to have his left eye enucleated or removed, but he is unsure as to the exact reason why.

Based on the initial presentation, both Zoe and Nirban have some form of retinal disorder. But first, a bit of physiology. If we zoom into the wall of the eye, it is made up of three major layers. There's a fibrous outer layer, which contains the cornea and sclera, and helps shield excess light. The middle vascular layer is called uvea and consists of the iris, pupil, choroid, and ciliary body. Finally, the neural layer consists of the retina, with its own outer pigmented layer, and an inner neural layer that’s composed of photoreceptor cells, which convert light into neural signals that travel via the optic nerve to the brain for visual processing.

Okay, let’s start with age-related macular degeneration or ARMD for short. This refers to an acquired degeneration of the macula, which is the central area of the retina. It can be divided into dry or non-exudative ARMD, which accounts for the vast majority of cases, and wet or exudative ARMD. Dry ARMD is characterized by yellowish extracellular deposits of waste materials that build up between the Bruch membrane and the retinal pigment epithelium. For your test, remember that these deposits are often known as Drusen. On the other hand, in wet ARMD, there is abnormal neovascularization, meaning that abnormal blood vessels grow from the choroid behind the retina and can leak intravascular fluid or blood. In terms of symptoms, dry ARMD usually presents with gradual vision problems, such as metamorphopsia, which is a type of distortion where linear objects appear curved or discontinuous, as well as scotomas or missing areas of vision, and eventually it can lead to central vision loss. In contrast, wet ARMD causes rapid central vision loss over a few weeks or months. Ultimately, individuals with ARMD can become legally blind, even though their peripheral vision remains intact. Diagnosis is based on fundoscopy, and treatment focuses on slowing vision loss. For dry ARMD, multivitamin and antioxidant supplements have been shown to help, while wet ARMD can be treated with injections of anti-vascular endothelial growth factors or anti-VEGF for short, like bevacizumab or ranibizumab, which inhibit neovascularization.

Fuentes

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Age-Related Macular Degeneration" Primary Care: Clinics in Office Practice (2015)
  4. "Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration" The Cochrane Database of Systematic Reviews (1999)
  5. "Antioxidant vitamin and mineral supplements for age-related macular degeneration" The Cochrane Database of Systematic Reviews (Complete Reviews) (2002)
  6. "Prevalence, incidence and future projection of diabetic eye disease in Europe: a systematic review and meta-analysis" European Journal of Epidemiology (2019)
  7. "Comprehensive Ophthalmology" JP Medical Ltd (2015)
  8. "Sonography of the Optic Nerve Sheath Diameter for Detection of Raised Intracranial Pressure Compared to Computed Tomography" Journal of Ultrasound in Medicine (2015)
  9. "The Retina" Springer Nature (2020)
  10. "Epidemiological Study of Nontraumatic Phakic Rhegmatogenous Retinal Detachment" Ophthalmic Research (2000)
Elsevier

Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.

RELX