Week 4: GI System Flashcards
What are the causes of toxic/ nutritional optic neuropathy?
alcoholism, tobacco/ substance use, certain medications, heavy metal exposure, poor nutrition
Poor nutrition: B1 deficiency; B12 malabsorption (pernicious anemia)
High risk meds: chloramphenicol, ethambutol, linezolid, isoniazid, digitalis, amiodarone, streptomycin, chlorpropamide, ethchlorvynol, disulfiram
What are the signs and symptoms of toxic/ nutritional optic neuropathy?
- VA 20/50-20/200
- Dyschromatopsia
- bilateral central or cecocentral visual field defects
- temporal disc pallor
- optic atrophy
- normal appearing disc initially
Which type of scotoma is ALWAYS associated with decreased visual acuity?
Central scotoma
Which type of scotoma involves the point of central fixatio nand the area between the blind spot and the fixation point?
cecocentral scotoma
Which type of scotoma affects an area of the visual field that is nasal or temporal to the point of central fixation?
paracentral scotoma
What leads to selective degeneration of RGCs in the region of the papillomacular bundle?
mitochondrial dysfunction
What is the recommended work up for toxic/ nutritional optic neuropathy?
- case hx: medication, drug, substance use, diet history
- color vision testing
- optic nerve assessment
- VF testing
- CVC with diff and peripheral smear
- Serum vitamin B1, B12, and folate levels
- Heavy metal screen
- Blood work to rule out Leber Hereditary Optic neuropathy
peripheral smear for morphologic description of RBC’s - helps ID type of anemia
What is the treatment for toxic/ nutritional optic neuropathy?
- eliminate causative agent (alcohol, tobacco, medication)
- Thiamine 100 mg BID
- Folate 1.0 mg QD
- multivitamin QD
- Bitamin B12 1,000 mg IM injection 1x/ month for pernicious anemia
What is the follow up for toxic/ nutritional optic neuropathy?
Initially monthly, then every 6-12 months
What is the most commoly inherited mitochondrial disorder?
Leber Hereditary Optic Neuropathy
What is the presentation for Leber?
Painless progressive vision loss in one eye and then the other eye in quick succession; mild swelling of optic disc that progresses over weeks, eventually optic atrophy; small telangiectatic blood vessels near the disk- not leaky on FA
Hydrophoic vitamins are packaged into chylomicrons and taken to which organ for storage?
Chylomicron: lipoprotein that contains triglycerides, cholesterol, fat-soluble vitamins, targeting proteins
Liver
Which vitamin deficiency is associated with bleeding?
Vitamin K
blood clotting cascade
Which vitamin deficiency is associated with ataxia, peripheral neuropathy and myopathy?
Vitamin E
What are the vitamin A derivatives in the transduction pathway?
all-trans-retinal; 11-cis retinol
A deficiency in which vitamin is a risk factor for multiple sclerosis?
Vitamin D
Which vitamin is an antioxidant that protects cells from free radicals?
Vitamin E
What is vitamin K a coenzyme for?
carboxylase
enzyme required for synthesis of proteins involved in blood clotting and bone metabolism
Do hydrophilic or hydrophobic vitamins need to be taken more frequently?
hydrophilic
removed in urine and not stored in the body
Which type of vitamins are more likely to develop toxic symptoms?
hydrophobic vitamins
Which vitamins are water soluble?
B’s and C’s
Which vitamin is thiamine?
B1
What is B1 used for in the body?
mitochondrial membrane development, enzymatic processes in brain function, interneuronal communication and regulation of immune cells and proteins
Where is B1 (thiamine) absorbed?
jejunum
transported in erythrocytes and plasma; stored in the liver in very small amounts
Which vitamin is involved int eh biosynthesis of neurotransmitters and maintains normal levels of homocysteine?
Vitamin B6 (pyridoxine)
What is the function of vitamin B6?
involved in gluconeogenesis, glycogenolysis, immune function and hemoglobin formation
Which drug inactivates vitamin B6 and is implicated in toxic/ nutritional optic neuropathy?
Isoniozid
What is vitamin B9/ folate needed for?
Proper cell division; DNA and purine synthesis and conversion of homocysteine to methionine
found in leafy greens, fruits, fortified cereals and meats
What condition is a hallmark of folate deficiency?
megaloblastic anemia
Which vitamin is known as cobalamin?
Vitamin B12
Deficiency of which vitamin is developed in patients that follow a vegan/ vegetarian diet, have a history of bariatric surgery or have malabsorptive diseases?
cobalamin deficiency (B12)
What is pernicious anemia?
An autoimmune disorder that prevents that absorption of vitamin B12 (cobalamin)
Which vitamin is required for collagen production, plays a vital role in wound healing AND can help regenerate other antioxidants in the body?
Vitamin C
may also slow the progression of cataracts
What ocular structure is believed to be protected by normal gut microbiota?
the retina
there are 6 normal gut microbiota, which 2 make up 80-90%?
firmicutes, bacteroidetes
what can result in the translocation of gut bacteria into the circulatory and lymphatic systems?
dysbiosis
Which systemic inflammatory conditions are associated with gut dysbiosis?
- Rheumatoid arthritis
- Multiple sclerosis
- Inflammatory bowel disease
- Type 1 diabetes
What non-infectious eye diseases are associated with gut commensal bacteria?
- autoimune uveitis
- ARMD
- Glucoma
- Diabetic Retinopathy
which ocular conditions are associated with dysbiosis of the ocular microbiota?
blepharitis, conjunctivitis, bacterial keratitis, trachoma, dry eye syndrome, meibomian gland dysfunction
H. pylori is implicated in what conditions?
peptic ulcer disease, glaucoma
What type of ulcers are a medical emergency?
perforated ulcers
cause severe, acute abdominal pain
What are the signs and symptoms of peptic ulcer disease?
- epigastric pain related to meals
- bleeding
what two conditions make up inflammatory bowel syndrome?
ulcerative colitis and crohn’s disease
fistulas are found in crohn’s disease/ ulcerative colitis
Crohn’s disease
What are the 3 classic ocular complications of IBS?
episcleritis, uveitis, scleritis
what are 4 secondary ocular complications that are seen in patients with IBS?
cataracts, neovascular glaucoma, nyctalopia and xerophthamia
What autosomal dominant condition is characterized by numerous adenomatous polyps lining the intestinal mucosal surface?
also presents with skeletal hamartomas (tumor like growths on skull, mandible, and long bones)
gardner syndrome
progresses to adenocarcinoma by 5th decade
What is an ocular manifestation of Gardner Syndrome?
presence of atypical CHRPE
bilateral, clusters of flat, well-demarcated lesions with 3-30 in each cluster increasing in size and pigmentation anteriorly toward fundus periphery
Which disorders make up the seronegative spondyloarthropathies?
- ankylosing spondylitis
- Reiter’s syndrome (reactive arthritis)
- Inflammatory bowel disease
- Psoriatic arthritis
what are ocular manifestations of inflammatory bowel disease?
episcleritis, scleritis, anterior uveitis, optic neuritis
xerophthalmia is the leading cause of what?
preventable blindness in developing countries
caused by severe vitamin A deficiency
what are the clinical signs of xerophthalmia?
- night blindness
- conjunctival xerosis
- bitot spots
- corneal xerosis
- corneal ulceration
- corneal scar
- xerophthamic fundus
what is unique about uveitis in regards to patients with IBD when comparing to episcleritis and scleritis?
Uveitis does not parallel the disease activity of IBD
