Arab Board Ophthalmology Final Written cheat sheet

Corneal epithelium regenerates from limbal stem cells; total limbal stem cell deficiency shows conjunctivalization, late fluorescein staining and loss of palisades of Vogt.

Recurrent corneal erosion: first-line is lubricants plus nocturnal ointment; refractory cases use epithelial debridement with diamond burr or alcohol delamination, or anterior stromal puncture.

Bacterial keratitis: scrape for Gram stain and cultures before antibiotics; contact-lens-related ulcers must cover Pseudomonas; hypopyon does not mandate steroids.

Acanthamoeba keratitis: ring infiltrate, radial keratoneuritis, pain out of proportion; culture on non-nutrient agar with E. coli; treat with polyhexamethylene biguanide plus chlorhexidine.

Fungal keratitis: feathery margins, satellite lesions, endothelial plaque; confocal microscopy and calcofluor white aid diagnosis; natamycin for filamentous, voriconazole/amphotericin for yeasts.

Fuchs endothelial dystrophy: guttae, corneal guttata, decreased endothelial density; hypertonic saline early, Descemet membrane endothelial keratoplasty when edema is visually significant.

Keratoconus: asymmetric astigmatism, inferior steepening, scissoring on retinoscopy; corneal cross-linking halts progression when topography or pachymetry shows documented progression.

Moorens ulcer (immune corneal melt) is treated with systemic immunosuppression; topical steroids alone may worsen melting.

Dry eye disease: tear film osmolarity and matrix metalloproteinase-9 are adjunct tests; cyclosporine or lifitegrast for chronic inflammation, punctal plugs after inflammation controlled.

Goldmann applanation tonometry: 1 mmHg error per 1.5 mmHg deviation from 520 g/mm²; central corneal thickness extremes bias readings.

Open-angle glaucoma diagnosis requires structural optic nerve damage (rim thinning, disc hemorrhage, retinal nerve fiber layer loss) with matching reproducible field defect.

Normal-tension glaucoma: exclude nocturnal hypotension, sleep apnea, vasospasm; treat with target pressure reduction of 30% from baseline.

Primary angle-closure: prophylactic laser peripheral iridotomy for fellow eye; acute attack needs topical and systemic pressure lowering, then iridotomy.

Trabeculectomy failure risk: young age, prior conjunctival surgery, uveitis, neovascular glaucoma; use antimetabolites (mitomycin C) in high-risk cases.

Selective laser trabeculoplasty is repeatable and can be primary therapy; prostaglandin analogs give the greatest intraocular pressure lowering among topical monotherapies.

Aqueous humor drains via trabecular meshwork into Schlemm canal (conventional) and via ciliary body/iris root into suprachoroidal space (uveoscleral).

Optic disc hemorrhage in glaucoma is a sign of progression, often inferior temporal and flame-shaped.

Topiramate can cause acute bilateral angle-closure with myopic shift from ciliary body effusion; treat by stopping the drug.

Diabetic retinopathy: panretinal photocoagulation for high-risk proliferative disease; anti-VEGF is first-line for center-involving diabetic macular edema.

Central retinal artery occlusion shows a cherry-red spot, boxcarring, and no cherry-red spot in cilioretinal artery sparing; workup includes carotid and cardiac evaluation.

Branch retinal vein occlusion: sector field defect, flame hemorrhages; macular edema treated with anti-VEGF or dexamethasone implant.

Retinal detachment: rhegmatogenous shows a tear with subretinal fluid and a corrugated appearance; repair by scleral buckle or vitrectomy with gas/oil tamponade.

Age-related macular degeneration: dry type shows drusen and geographic atrophy; wet type shows choroidal neovascular membrane and responds to anti-VEGF.

Retinopathy of prematurity screening: infants under 1500 g birthweight or under 32 weeks gestation; treat type 1 disease with laser or anti-VEGF.

Vitreous hemorrhage with no view of the retina: B-scan ultrasound to exclude detachment before considering vitrectomy.

Central serous chorioretinopathy: serous macular detachment on optical coherence tomography; risk factors include corticosteroid use and type A personality.

Cystoid macular edema after cataract surgery is confirmed by fluorescein angiography (petaloid leakage) or optical coherence tomography; treat with topical NSAIDs and steroids.

Anterior uveitis: cells and flare in the anterior chamber; HLA-B27-associated cases are often unilateral and recurrent; treat with topical steroids and cycloplegics.

Hypopyon uveitis with retinal vasculitis suggests Behçet disease; treat with systemic immunosuppression and biologics such as infliximab.

Toxoplasmosis retinochorioretinitis: focal necrotizing lesion adjacent to a scar with overlying vitritis; classic "headlight in the fog".

Sympathetic ophthalmia occurs after penetrating trauma or surgery in the exciting eye; treat with systemic steroids and immunosuppression; enucleation only if eye is blind and within 2 weeks.

Vogt-Koyanagi-Harada disease: bilateral panuveitis with serous detachments, meningismus, vitiligo and poliosis; treat with high-dose systemic steroids.

Juvenile idiopathic arthritis-associated uveitis is often asymptomatic with band keratopathy; screen with slit lamp at regular intervals.

Sarcoidosis uveitis: mutton-fat keratic precipitates, iris nodules, retinal periphlebitis; chest imaging and angiotensin-converting enzyme levels support diagnosis.

Cytomegalovirus retinitis in HIV shows a "pizza pie" or brushfire border with hemorrhages; treat with ganciclovir or valganciclovir and antiretroviral therapy.

HLA-B27 testing has low positive predictive value; diagnosis of spondyloarthropathy-related uveitis remains clinical.

Orbital cellulitis: fever, proptosis, ophthalmoplegia, pain; requires urgent imaging and intravenous antibiotics; watch for cavernous sinus thrombosis.

Orbital compartment syndrome: proptosis with elevated intraocular pressure and afferent pupillary defect; emergent lateral canthotomy and cantholysis.

Thyroid eye disease: order computed tomography to assess apical crowding before surgery; smoking cessation reduces progression; steroids for active inflammation.

Basal cell carcinoma is the most common eyelid malignancy; margins controlled by Mohs micrographic surgery for medial canthus lesions.

Dacryocystorhinostomy is indicated for nasolacrimal duct obstruction with epiphora and dacryocystitis; silicone stents may be used.

Ptosis: levator function above 10 mm favors levator resection; poor function favors frontalis sling.

Orbital lymphoma presents as a painless, rubbery mass; biopsy is essential because lymphoma can mimic inflammation.

Lacrimal gland pleomorphic adenoma requires complete excision with intact capsule; incisional biopsy risks recurrence.

Amblyopia treatment: patching or atropine penalization; critical period ends around age 7-9, but treatment can still work in older children.

Leukocoria differential includes retinoblastoma, congenital cataract, retinopathy of prematurity, Coats disease and persistent fetal vasculature.

Congenital esotropia presents before 6 months with a large angle and cross-fixation; treat with early surgery.

Accommodative esotropia: hypermetropic refraction corrected; residual deviation may need bifocals or surgery.

Intermittent exotropia: assess control and stereopsis; surgery for deterioration or poor control.

Retinoblastoma: leukocoria and strabismus; heritable RB1 mutation with bilateral disease; enucleation, chemotherapy and focal therapy.

Congenital nasolacrimal duct obstruction: conservative management with massage until 12 months; probing if persistent.

Duane syndrome: limitation of abduction with globe retraction on adduction; usually no treatment required.

Optic neuritis: painful vision loss, afferent pupillary defect, dyschromatopsia; multiple sclerosis association; treat with intravenous steroids for faster recovery.

Anterior ischemic optic neuropathy: altitudinal field defect, sector pallor, no pain on eye movement; non-arteritic type associated with vasculopathy.

Giant cell arteritis: age over 50, headache, jaw claudication, elevated erythrocyte sedimentation rate; start steroids immediately and biopsy.

Papilledema: bilateral disc edema with preserved visual acuity; elevated intracranial pressure; imaging then lumbar puncture.

Third nerve palsy with pupil involvement suggests compressive lesion (aneurysm); pupil sparing favors ischemic cause.

Horner syndrome: ptosis, miosis, anhidrosis; postganglionic lesions show delayed dilation on apraclonidine testing.

Internuclear ophthalmoplegia: impaired adduction with abducting nystagmus; lesion in medial longitudinal fasciculus; bilateral in multiple sclerosis.

Leber hereditary optic neuropathy: painless sequential vision loss in young males; mitochondrial DNA mutation.

Phacoemulsification: divide-and-conquer or chop techniques; capsulorhexis diameter about 5 mm for adequate overlap.

Posterior capsule rupture with vitreous loss: stop phacoemulsification, perform anterior vitrectomy, place intraocular lens in sulcus or anterior chamber.

Endophthalmitis after cataract surgery: presents within days with pain and hypopyon; treat with intravitreal antibiotics (vancomycin plus ceftazidime).

Refractive surgery: laser in situ keratomileusis flap thickness around 100-160 microns; photorefractive keratectomy removes epithelium.

Corneal ectasia after laser in situ keratomileusis: risk with thin residual stromal bed (under 250 microns) and forme fruste keratoconus.

Intraocular lens power calculation: use optical biometry; adjust for prior myopic laser refractive surgery using keratometry history.

Toric intraocular lens alignment: mark axis preoperatively; residual astigmatism under 0.75 diopters is generally acceptable.

Pediatric cataract surgery requires early surgery to prevent dense amblyopia and posterior capsule management with capsulotomy.

Uveal melanoma: ultrasonography shows a dome-shaped lesion with low internal reflectivity; treat with plaque brachytherapy or enucleation.

Retinoblastoma histology: Flexner-Wintersteiner rosettes; calcification on imaging supports diagnosis.

Conjunctival melanoma: arises from primary acquired melanosis or nevus; wide local excision with cryotherapy.

Sebaceous carcinoma: yellow eyelid lesion, pagetoid spread, can mimic chalazion; biopsy is mandatory.

Choroidal nevus versus melanoma: thickness over 2 mm, subretinal fluid, orange pigment and symptoms favor melanoma.

Orbital rhabdomyosarcoma: child with rapid proptosis; treat with chemotherapy and radiation.

Squamous cell carcinoma of conjunctiva: gelatinous lesion with feeder vessels; treat with excision, cryotherapy and topical mitomycin C.

Metastatic choroidal tumor is the most common intraocular malignancy in adults; breast and lung primaries predominate.

Snell law: n1 sin(theta1) = n2 sin(theta2); refractive index of cornea about 1.376, aqueous 1.336, lens 1.42.

Gullstrand reduced eye: power about 60 diopters, axial length 22.22 mm, nodal point 7.08 mm from cornea.

Spherical equivalent = sphere + (cylinder/2); use for rough refractive estimation.

Contact lens: rigid gas permeable lenses correct irregular astigmatism better than soft lenses; keratoconus fitting uses steeper base curve.

Oxygen transmissibility (Dk/t) determines corneal hypoxia risk; silicone hydrogel lenses have high Dk.

Vertex distance matters for powers above 4 diopters; spectacle-to-contact conversion uses vertex formula F = F/(1 - dF).

Prism diopter = 100 x tan(deviation angle); Prentice rule: prism power = decentration (cm) x lens power (diopters).

Anisometropia: difference of 1 diopter or more; amblyopia risk in children requires correction.

Chemical injury: immediate copious irrigation for at least 30 minutes; check pH; alkali penetrates more than acid.

Open globe: shield eye, no pressure, intravenous antibiotics, tetanus prophylaxis, urgent surgical repair; avoid manipulation.

Intraocular foreign body: computed tomography for metallic foreign body; magnetic removal with caution; endophthalmitis prophylaxis.

Traumatic hyphema: elevate head, avoid aspirin and nonsteroidal anti-inflammatory drugs; screen for sickle cell trait in black patients.

Retinal detachment after trauma: examine periphery with scleral depression; treat tears with laser or cryotherapy.

Orbital blowout fracture: restricted upgaze, enophthalmos, infraorbital numbness; repair if muscle entrapment or large defect.

Corneal abrasion: topical antibiotic, no patching for contact lens wearers; re-examine in 24 hours.

Commotio retinae: retinal whitening after blunt trauma; observe, may resolve spontaneously.

Aqueous humor is produced by the ciliary epithelium via active secretion (carbonic anhydrase and Na/K ATPase) and ultrafiltration.

Corneal transparency depends on uniform collagen spacing and relative dehydration maintained by endothelial pump.

Visual cycle: rhodopsin regenerates via retinal pigment epithelium; vitamin A deficiency causes night blindness and xerophthalmia.

Pharmacology: timolol is a nonselective beta blocker; avoid in asthma; latanoprost is a prostaglandin F2 alpha analog.

Microbiology: Staphylococcus aureus is the most common cause of bacterial conjunctivitis; Pseudomonas in contact lens wearers.

Evidence-based practice: randomized controlled trials give highest evidence for therapy; number needed to treat = 1/absolute risk reduction.

Genetics: retinoblastoma follows Knudson two-hit hypothesis; Leber hereditary optic neuropathy is maternally inherited mitochondrial DNA.

Ocular immunology: anterior chamber-associated immune deviation suppresses delayed hypersensitivity in the anterior chamber.