Cataract

Primary open-angle glaucoma is a chronic, usually asymptomatic optic neuropathy with a normal iridocorneal angle, progressive cupping of the optic disc, and characteristic peripheral-before-central visual field loss. Diagnosis rests on tonometry, gonioscopy to confirm the open angle, dilated funduscopy with cup-disc ratio, and perimetry, and treatment is lifelong topical IOP-lowering therapy escalating to laser or incisional surgery for uncontrolled disease.

Acute angle-closure glaucoma is a pupillary-block emergency in which sudden closure of the iridocorneal angle blocks aqueous outflow, causing severe eye pain, halos, and rapidly rising intraocular pressure that can blind the eye within hours if not treated. Diagnosis is clinical plus tonometry and gonioscopy; treatment is immediate topical and systemic IOP-lowering therapy followed by laser peripheral iridotomy.

Age-related macular degeneration is a leading cause of irreversible blindness in older adults in resource-rich countries, presenting as painless central vision loss from drusen and retinal pigment epithelium change (dry AMD) or choroidal neovascularization (wet AMD). Dry AMD is managed with AREDS2 supplementation and risk-factor control; wet AMD is treated with intravitreal anti-VEGF injection.

Rhegmatogenous retinal detachment is a surgical emergency in which a full-thickness retinal break lets liquefied vitreous separate the neurosensory retina from the retinal pigment epithelium, presenting with flashes, floaters, and an advancing visual field curtain. Diagnosis is by dilated indirect ophthalmoscopy with scleral depression, and treatment is prompt surgical reattachment, most urgent while the fovea is still spared.

Uveitis is inflammation of the uveal tract, classified by anatomic location as anterior, intermediate, posterior, or panuveitis and by systemic association such as HLA-B27 spondyloarthritis, sarcoidosis, or Behcet disease. Anterior uveitis presents with a painful red eye and photophobia diagnosed at the slit lamp, while posterior uveitis presents with painless floaters or vision loss, and treatment is topical corticosteroid for anterior disease escalating to systemic corticosteroid and steroid-sparing immunosuppression for recurrent, severe, or posterior-segment disease.

Autosomal dominant NF2 (merlin) gene disorder causing bilateral vestibular schwannomas, meningiomas, and juvenile cataracts; diagnosed by clinical criteria and MRI with gadolinium, and managed with hearing-preserving surgery, stereotactic radiosurgery, and bevacizumab for progressive schwannomas.

Microbial keratitis (infectious corneal ulcer) is the unifying vision-threatening syndrome of a painful red eye with a corneal infiltrate, produced by bacterial, viral, fungal, or amebic invasion of a breached corneal epithelium, managed by the same urgent pathway regardless of organism: emergent scraping for smear and culture before any drug is given, then broad empiric coverage narrowed once results return. Delay, misdiagnosis as simple conjunctivitis, or premature corticosteroid use converts a treatable ulcer into stromal melt, perforation, and permanent vision loss.

Endophthalmitis is a vision-threatening suppurative infection of the aqueous and vitreous humors, most often exogenous after cataract or other intraocular surgery and less often endogenous from hematogenous seeding during bacteremia or candidemia. Diagnosis is clinical, confirmed by vitreous/aqueous tap, and treatment is emergent intravitreal antibiotics or antifungals with vitrectomy for severe cases.