Iran Ophthalmology Specialty Board flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Vergence formula

For a thin lens, image vergence equals object vergence plus lens power (V' = V + F), with vergence equal to refractive index divided by distance in meters.

Knapp's rule

In axial ametropia, spectacle correction at the anterior focal plane (about 13 mm vertex distance) produces a retinal image size comparable to that of an emmetropic eye.

Vertex distance conversion

When a lens is moved, new power equals old power divided by one minus the distance moved in meters times old power; moving a strong minus lens closer weakens it.

Duochrome test principle

Longitudinal chromatic aberration makes red focus behind and green focus in front of the retina; in myopia red is clearer, in hyperopia green is clearer, refining sphere only.

Corneal ulcer empiric therapy

Bacterial keratitis is treated with fortified cefazolin 5% plus tobramycin 1.3% hourly; contact-lens-related ulcers require anti-Pseudomonas coverage and consideration of antifungal therapy.

Acanthamoeba keratitis clues

Ring infiltrate, radial keratoneuritis, pain out of proportion to signs, and contact lens exposure to tap water suggest Acanthamoeba; diagnosis uses non-nutrient agar with E. coli overlay or confocal microscopy.

Fuchs endothelial dystrophy

Bilateral guttae and reduced endothelial cell density cause corneal edema; early disease is managed with hypertonic saline and advanced disease with endothelial keratoplasty.

Corneal layers

From anterior to posterior: epithelium, Bowman's layer, stroma (about 90% thickness, collagen type I), Descemet's membrane (type IV), and non-replicating endothelium.

Optical biometry

Partial coherence interferometry measures axial length with high precision and is preferred over ultrasound; immersion or optical biometry plus keratometry feeds IOL power formulas.

Intraoperative floppy iris

Associated with tamsulosin and other alpha-1 antagonists; managed with preoperative atropine, intracameral phenylephrine, cohesive viscoelastic, and iris hooks or pupil expanders.

Endophthalmitis prophylaxis

Intracameral cefuroxime (1 mg/0.1 mL) or moxifloxacin at the end of cataract surgery reduces endophthalmitis risk; postoperative pain with hypopyon requires vitreous tap and intravitreal antibiotics.

Pediatric cataract timing

Dense unilateral congenital cataract requires surgery within the first 6–8 weeks of life, and bilateral cataracts within about 10 weeks, to prevent irreversible amblyopia.

Goldmann tonometry principle

Applanation pressure equals force divided by area with a 3.06 mm diameter; thin corneas underestimate and thick corneas overestimate true intraocular pressure.

Acute angle-closure management

Lower pressure with topical beta-blocker and alpha-agonist, pilocarpine, systemic acetazolamide, and osmotic agents, then perform laser peripheral iridotomy to relieve pupillary block.

Glaucomatous field defects

Nerve fiber layer bundle damage produces nasal steps, arcuate scotomas, paracentral scotomas, and altitudinal defects; field loss respects the horizontal midline.

Diabetic retinopathy grading

Nonproliferative disease shows microaneurysms, dot-blot hemorrhages, hard exudates, and cotton-wool spots; proliferative disease adds neovascularization, vitreous hemorrhage, or tractional detachment.

Central retinal artery occlusion

Sudden painless monocular vision loss with a cherry-red spot, boxcarring, and an afferent pupillary defect; retinal survival is about 90 minutes and embolic sources must be sought.

ROP screening criteria

Screen infants born at 30 weeks gestation or less or weighing 1500 g or less; first exam at 4–6 weeks postnatal age or 31–33 weeks postmenstrual age.

Granulomatous uveitis signs

Mutton-fat keratic precipitates and iris nodules (Koeppe at the pupillary margin, Busacca on the stroma) suggest sarcoidosis, tuberculosis, syphilis, VKH, or sympathetic ophthalmia.

Toxoplasma retinochoroiditis

Focal necrotizing retinitis adjacent to a pigmented scar with marked vitritis ('headlight in the fog'); treated with pyrimethamine plus sulfadiazine and folinic acid.

Sympathetic ophthalmia

Bilateral granulomatous panuveitis after penetrating trauma or surgery in the exciting eye; enucleation within 2 weeks of injury reduces risk and immunosuppression is the mainstay.

Relative afferent pupillary defect

Detected with the swinging flashlight test; indicates optic nerve or severe retinal disease on the affected side and is not caused by media opacity or mild cataract.

Pupil-involving third nerve palsy

Ptosis, a down-and-out eye, and mydriasis suggest compression, most often a posterior communicating artery aneurysm, and require urgent angiography or MRA.

Giant cell arteritis

Age over 50 with headache, jaw claudication, scalp tenderness, and elevated ESR or CRP requires immediate high-dose corticosteroids and temporal artery biopsy within 2 weeks.

Involutional ectropion repair

Horizontal lid laxity causes outward turning of the lower lid; lateral tarsal strip tightens the lid, while cicatricial ectropion from scarring requires grafting.

Orbital compartment syndrome

Acute proptosis, pain, and vision loss after trauma or surgery, often from retrobulbar hemorrhage, require emergent lateral canthotomy and cantholysis to decompress the orbit.

Leukocoria differential

Retinoblastoma, congenital cataract, persistent fetal vasculature, Coats disease, toxocariasis, and retinal detachment can all present with a white pupillary reflex and require urgent evaluation.

Congenital glaucoma

Buphthalmos, corneal edema, photophobia, and tearing with elevated intraocular pressure; treated with goniotomy or trabeculotomy, with medical therapy as adjunct, examined under anesthesia.

Choroidal nevus versus melanoma

Thickness over 2 mm, subretinal fluid, orange pigment, acoustic hollowness, and a margin within 3 mm of the optic disc favor melanoma over a benign nevus.

Sebaceous carcinoma

An eyelid tumor often misdiagnosed as chalazion or blepharitis, with pagetoid spread; requires wide excision or Mohs surgery with map biopsies for margin control.

Sensitivity and specificity

Sensitivity is true positives divided by all diseased; specificity is true negatives divided by all non-diseased; both are independent of disease prevalence in the population.

Trachoma SAFE strategy

Trachoma from Chlamydia trachomatis serovars A–C is controlled with surgery for trichiasis, antibiotics (azithromycin), facial cleanliness, and environmental improvement; WHO grades TF, TI, TS, TT, CO.