Disease Overviews
Diseases
High-yield, cited summaries of ophthalmic conditions — organized for rotations and boards review.
Acanthamoeba Keratitis
Acanthamoeba keratitis (AK) is a severe, often diagnostically delayed corneal infection caused by a free-living protozoan found ubiquitously in water and soil, strongly associated with contact lens wear and exposure to contaminated water. It classically causes pain disproportionate to clinical findings and radial perineural infiltrates. Treatment relies on prolonged combination biguanide/diamidine antiamoebic therapy, with diagnostic delay and cyst drug-resistance as major contributors to poor outcomes.
Adenoviral Conjunctivitis (Epidemic Keratoconjunctivitis)
Adenoviral conjunctivitis is the most common cause of infectious conjunctivitis, ranging from mild follicular conjunctivitis to epidemic keratoconjunctivitis (EKC) with corneal subepithelial infiltrates. It is highly contagious, primarily a clinical diagnosis, and managed supportively, since no antiviral therapy is definitively established. Diagnostic accuracy from clinical impression alone is under 50%, and infection control is a central part of management given the risk of outbreaks.
Age-Related Cataract
Age-related cataract is progressive opacification of the crystalline lens driven by oxidative stress and dysregulated autophagy in lens epithelial cells, and it remains the leading treatable cause of vision impairment worldwide. Diagnosis is clinical, via slit-lamp and red-reflex examination, and the only effective treatment is surgical extraction with intraocular lens implantation. Risk factors include age, smoking, and cumulative ultraviolet/ionizing radiation exposure, and cataract-related visual impairment carries a substantial economic and quality-of-life burden.
Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is a leading cause of blindness worldwide, primarily affecting individuals older than 55 years. It threatens central high-acuity vision required for reading, driving, and facial recognition. AMD is classified into early, intermediate, and late stages, with late AMD divided into neovascular (wet) and atrophic (dry) subtypes. The disease is characterized by drusen accumulation, Bruch's membrane changes, and progressive dysfunction of the retinal pigment epithelium. While anti-VEGF therapy has revolutionized treatment of neovascular AMD, management of atrophic disease has been limited until recent complement inhibitor trials. Risk factor modification and dietary supplementation may slow disease progression in earlier stages.
Allergic Conjunctivitis
Allergic eye disease is an IgE-mediated (and in chronic forms, mixed-hypersensitivity) ocular surface condition affecting an estimated 15-40% of people worldwide. It spans a spectrum from mild seasonal/perennial allergic conjunctivitis to sight-threatening vernal and atopic keratoconjunctivitis with corneal involvement. Diagnosis is clinical; management is stepwise from allergen avoidance through topical antihistamines/mast-cell stabilizers to short-course steroids and immunomodulators for severe disease.
Amblyopia
Amblyopia is reduced best-corrected visual acuity from abnormal visual development during childhood, most commonly due to strabismus, anisometropia, or visual deprivation, and is the leading cause of monocular vision impairment in children. Conventional occlusion (patching) therapy remains the evidence-based first-line active treatment; digital binocular gaming therapies show short-term benefit but current high-quality evidence supports patching as superior for long-term outcomes.
Anterior Uveitis
Anterior uveitis is the most common form of uveitis, characterized by inflammation of the iris and ciliary body. Clinical presentation ranges from acute unilateral episodes to chronic bilateral disease, with etiologies spanning infectious (viral, bacterial), autoimmune (HLA-B27-associated, juvenile idiopathic arthritis), and idiopathic causes. Diagnosis relies on clinical characterization including laterality, granulomatous features, and presence of elevated intraocular pressure or corneal involvement. Management typically involves topical corticosteroids, with systemic immunomodulatory therapy reserved for refractory or severe cases, and antiviral therapy for confirmed viral etiologies.
Astigmatism
Astigmatism is a refractive error caused by unequal corneal or lenticular curvature across different meridians, producing two focal points instead of one and resulting in blurred or distorted vision at all distances. Regular astigmatism is common across all ages and is easily corrected optically, but irregular or rapidly progressive astigmatism — particularly if asymmetric between eyes — is an important red flag for corneal ectasia such as keratoconus and warrants prompt corneal evaluation rather than simple lens correction.
Bacterial Keratitis
Bacterial keratitis is a corneal infection requiring urgent recognition and treatment with topical antimicrobials. It represents a major cause of infectious keratitis in high-income countries and can lead to severe visual loss from corneal ulceration, opacity, and scarring even with appropriate treatment. Approximately 50% of clinically suspected cases remain culture-negative despite typical presentation. Risk factors, bacterial isolates, and antimicrobial resistance patterns vary significantly between high-income and low- or middle-income countries, necessitating region-specific management approaches.
Blepharoptosis
Blepharoptosis (ptosis) is abnormal drooping of the upper eyelid margin below its normal resting position, which can be congenital or acquired and may signal anything from benign age-related aponeurotic stretching to a life-threatening neurologic emergency. Accurate categorization by mechanism — aponeurotic, myogenic, neurogenic, or mechanical — and recognition of red-flag features (pupil involvement, variability, other cranial nerve findings) are essential, since management ranges from observation or nonsurgical options to urgent neurologic workup or surgical repair.
Central Retinal Artery Occlusion
Central retinal artery occlusion (CRAO) is an ophthalmic emergency characterized by acute obstruction of the central retinal artery, resulting in inner retinal ischemia and typically severe, sudden vision loss. Often described as a 'stroke of the eye,' CRAO represents a small vessel stroke affecting retinal ganglion cells, which are part of the central nervous system. The condition has a poor visual prognosis, with many patients left with counting fingers vision or worse. CRAO is classified into four distinct clinical entities with varying outcomes, and patients require urgent evaluation to rule out arteritic causes and assess for underlying systemic vascular disease.
Chalazion & Hordeolum
Chalazion (a chronic, non-infectious granulomatous inflammation from an obstructed meibomian or Zeis gland) and hordeolum (an acute, painful, typically infectious inflammation of an eyelid gland) are among the most common eyelid conditions seen in ophthalmology, together accounting for a large share of eyelid presentations in general and remote/teleophthalmology practice. Most cases resolve with conservative measures, with intralesional corticosteroid injection or incision and curettage reserved for persistent lesions.
Chemical Burns of the Eye
Ocular chemical burns, particularly from alkali agents, are true ophthalmic emergencies requiring immediate copious irrigation before any other assessment. Severity is graded using the Roper-Hall or Dua classification systems based on corneal clarity and limbal ischemia, which predicts prognosis and risk of limbal stem cell deficiency. Mild-to-moderate injuries have a good prognosis with topical treatment, while severe injuries (especially assault with ammonia) frequently progress to total limbal stem cell deficiency despite aggressive management.
Congenital Nasolacrimal Duct Obstruction (CNLDO)
Congenital nasolacrimal duct obstruction (CNLDO), the most common cause of persistent epiphora and discharge in infancy, results from a membranous occlusion at the valve of Hasner that resolves spontaneously in the large majority of cases within the first year of life. Management is staged, beginning with conservative measures (lid hygiene, lacrimal sac massage) and escalating to probing, intubation, or, rarely, dacryocystorhinostomy as needed based on age, severity, and treatment response.
Corneal Abrasion & Recurrent Erosion Syndrome
Corneal abrasion is a common traumatic epithelial defect that usually heals within days with supportive care, but can be complicated by recurrent corneal erosion syndrome (RCES) — episodic breakdown of poorly adherent healed epithelium, classically on waking. Management is largely supportive, with hypertonic saline, bandage contact lenses, and (for refractory RCES) epithelial debridement or anterior stromal micropuncture used to promote durable epithelial adhesion.
Dacryocystitis & Nasolacrimal Duct Obstruction
Nasolacrimal duct obstruction (NLDO) causes chronic epiphora and predisposes to dacryocystitis, infection of the lacrimal sac secondary to stagnant tear outflow. Dacryocystorhinostomy (DCR), performed externally or endoscopically, is the definitive treatment for chronic NLDO and recurrent dacryocystitis, with high success rates; systemic risk factors such as diabetes and anatomic factors like a deviated nasal septum are associated with surgical failure, and a lacrimal sac mass or atypical presentation should always raise concern for an underlying neoplasm.
Diabetic Retinopathy
The leading cause of vision loss in working-age adults — a microvascular complication of diabetes staged from mild NPDR through PDR, with management tied directly to stage.
Dry Eye Disease
Dry eye disease (DED) is a common, multifactorial ocular surface disease defined by loss of tear film/ocular surface homeostasis, with tear film instability, hyperosmolarity, inflammation, and neurosensory abnormalities as etiological drivers. Per the TFOS DEWS framework, it is always symptomatic and is diagnosed using a structured screening-questionnaire-plus-objective-testing algorithm, then subclassified as evaporative or aqueous-deficient to guide targeted management.
Ectopia Lentis & Lens Subluxation
Ectopia lentis is displacement of the crystalline lens from its normal position due to zonular weakness or rupture, most classically associated with Marfan syndrome but also caused by trauma, homocystinuria, and other connective tissue or metabolic disorders. Severe subluxation risks angle-closure glaucoma, lens-induced uveitis, and retinal detachment, and surgical management has advanced considerably with techniques like sutureless intrascleral IOL fixation and specialized lens aspiration approaches for extremely unstable lenses.
Endophthalmitis
Endophthalmitis is severe intraocular infection/inflammation involving the vitreous and often anterior chamber, most commonly following cataract surgery or intravitreal injection, and represents an ophthalmic emergency requiring prompt intravitreal antimicrobial therapy. Rising antimicrobial resistance, particularly among coagulase-negative staphylococci and Gram-negative organisms in some regions, is complicating empiric treatment and worsening outcomes in resistant cases.
Entropion & Ectropion
Entropion (inward turning of the eyelid margin) and ectropion (outward turning of the eyelid margin) are common eyelid malpositions, most often involutional (age-related) in origin, that disrupt normal lid-globe apposition and can threaten the ocular surface if untreated. Surgical correction — including techniques such as the modified Wheeler's method for entropion and the lateral tarsal strip procedure for ectropion — is highly effective, producing significant symptom relief and quality-of-life improvement with generally low complication rates.
Epiretinal Membrane
Epiretinal membrane (ERM) is a fibrocellular proliferation on the retinal surface, most often idiopathic and age-related, that can cause metamorphopsia and gradual vision loss through tangential traction on the macula. Most ERMs are mild and stable and can be observed; surgical removal (pars plana vitrectomy with membrane peeling) is reserved for visually significant or progressive cases.
Eyelid Malignancy: Basics
Basal cell carcinoma is the most common eyelid malignancy, followed by sebaceous cell carcinoma, with squamous cell carcinoma, melanoma, and Merkel cell carcinoma comprising the remaining major eyelid cancer types. Microscopically controlled surgical excision (including Mohs micrographic surgery) is the mainstay of curative treatment, with lymph node involvement and positive surgical margins the strongest predictors of local recurrence; immunotherapy and targeted agents have expanded treatment options for unresectable or metastatic disease.
Fuchs Endothelial Corneal Dystrophy
Fuchs endothelial corneal dystrophy (FECD) is a progressive, bilateral disorder of corneal endothelial cell loss and guttae formation, strongly associated with a CTG trinucleotide repeat expansion in the TCF4 gene, leading to corneal edema and visual loss in advanced disease. Management ranges from observation and hypertonic saline in early disease to Descemet membrane endothelial keratoplasty (DMEK), now the preferred surgical treatment, in advanced disease.
Fungal Keratitis
Fungal keratitis is an aggressive corneal infection, most commonly caused by filamentous fungi (Fusarium, Aspergillus) or yeasts (Candida), and is a leading cause of corneal blindness in tropical and subtropical regions. It classically follows vegetative trauma or occurs in contact lens wearers and immunosuppressed patients. Diagnosis is often delayed because clinical signs overlap with bacterial keratitis; treatment relies on topical antifungals (natamycin, voriconazole), with surgery or emerging adjuncts like intracameral amphotericin B reserved for refractory disease.
Giant Cell Arteritis & Ischemic Optic Neuropathy
Ischemic optic neuropathy is a leading cause of severe, sudden vision loss in patients over 50, and the single most important diagnostic branch point is arteritic (from giant cell arteritis) versus non-arteritic disease. Arteritic ischemic optic neuropathy is a true ophthalmic emergency: untreated giant cell arteritis carries a high risk of fellow-eye involvement within days, so treatment with high-dose corticosteroids should begin on clinical suspicion, before biopsy confirmation.
Herpes Zoster Ophthalmicus
Herpes zoster ophthalmicus (HZO) is a vision-threatening condition caused by reactivation of latent varicella zoster virus in the ophthalmic division of the trigeminal nerve (V1). It typically affects older and immunocompromised patients and is characterized by a unilateral vesicular eruption in the V1 dermatome. Ocular involvement occurs in approximately 50% of cases and can lead to significant morbidity including chronic pain and vision loss. Timely antiviral therapy is essential to minimize complications.
Horner Syndrome
Horner syndrome results from disruption of the three-neuron oculosympathetic pathway anywhere from the hypothalamus to the eye, producing the classic triad of ptosis, miosis, and anhidrosis. Localizing the lesion to a central, preganglionic, or postganglionic level is essential because each level carries a different differential — including, in preganglionic disease, potentially life-threatening causes like apical lung tumors, and in children, neuroblastoma.
Hyperopia & Presbyopia
Hyperopia (farsightedness) and presbyopia (age-related loss of accommodation) are both refractive conditions of insufficient effective plus power, but arise from distinct mechanisms and affect different populations: hyperopia reflects an eye that is too short (or optically underpowered) relative to its axial length, while presbyopia reflects progressive age-related stiffening of the crystalline lens and ciliary apparatus. Management has expanded well beyond spectacles and contact lenses to include emerging pharmacological options for presbyopia and individualized approaches for amblyogenic hyperopia in children.
Hypertensive Retinopathy
Hypertensive retinopathy is the spectrum of retinal vascular changes caused by chronic or acute systemic hypertension, ranging from mild arteriolar narrowing to malignant hypertensive retinopathy with disc edema, hemorrhages, and exudates. Malignant hypertensive retinopathy signals a hypertensive emergency requiring urgent blood pressure control and can rarely present with ischemic optic neuropathy.
Infectious Uveitis: Toxoplasmosis & CMV Retinitis
Ocular toxoplasmosis and cytomegalovirus (CMV) retinitis are the two most clinically important infectious causes of posterior uveitis and retinitis. Toxoplasmosis is the most common infectious cause of posterior uveitis worldwide, typically affecting immunocompetent hosts as focal necrotizing retinochoroiditis, while CMV retinitis occurs almost exclusively in immunocompromised patients and follows a more indolent but potentially blinding course if untreated.
Intermediate Uveitis & Pars Planitis
Intermediate uveitis is inflammation centered on the vitreous and pars plana, with pars planitis referring to the idiopathic form characterized by snowballs and snowbanks. It typically affects young adults, more often females, and presents with floaters and blurred vision rather than pain or redness. Not all cases require treatment — mild disease without significant vascular leakage or complications can often be safely observed.
IOL Power Calculation: Basics
Intraocular lens (IOL) power calculation aims to select an IOL power that produces a targeted postoperative refraction, relying on accurate ocular biometry (axial length, keratometry, anterior chamber depth) and an appropriate calculation formula. Formulas have evolved from historical regression-based equations through vergence and ray-tracing methods to modern artificial intelligence-based approaches, which generally reduce prediction error, particularly in eyes with atypical biometry such as very long or very short axial lengths, or those with prior corneal refractive surgery.
Keratoconus
Keratoconus is a bilateral, typically asymmetric progressive corneal ectasia causing stromal thinning, steepening, and irregular astigmatism, most commonly developing in the second and third decades of life. Eye rubbing, atopy, and family history are recognized risk factors. Diagnosis relies primarily on corneal topography/tomography; management ranges from spectacles and specialty contact lenses for mild disease to corneal cross-linking to halt progression and, for severe cases, corneal transplantation.
Leukocoria: Differential Diagnosis
Leukocoria — an abnormal white pupillary reflex — is a pediatric ophthalmic emergency until proven otherwise, since it is the most common presenting sign of retinoblastoma, a potentially life-threatening intraocular malignancy. A broad range of non-malignant conditions (cataract, persistent fetal vasculature, Coats disease, retinopathy of prematurity) can also cause leukocoria, and rare malignant mimickers make prompt, expert ocular oncology evaluation essential for any child presenting with this finding.
Macular Hole
Idiopathic full-thickness macular hole is a foveal defect caused by anteroposterior and tangential vitreomacular traction, presenting with central vision loss and metamorphopsia. Pars plana vitrectomy with internal limiting membrane peeling and gas tamponade achieves closure in the large majority of cases, including large holes, with 27-gauge small-incision techniques offering a favorable safety profile.
Myopia
Myopia (nearsightedness) is a refractive error in which the eye's optical power exceeds its axial length, causing distant images to focus in front of the retina. Childhood-onset myopia is a growing global public health concern because axial elongation, particularly high myopia, carries lifelong risk of sight-threatening complications. Multiple evidence-based interventions now exist to slow pediatric myopia progression, though none halts it completely, and several long-held beliefs in the field lack robust supporting evidence.
Neovascular Glaucoma
Neovascular glaucoma (NVG) is a severe, vision-threatening secondary glaucoma driven by pathologic neovascularization of the iris and anterior chamber angle, most commonly secondary to ischemic retinal disease (proliferative diabetic retinopathy, central retinal vein occlusion, ocular ischemic syndrome). Management requires two parallel strategies — rapid anti-VEGF-mediated suppression of neovascularization and definitive treatment of the underlying retinal ischemia (typically panretinal photocoagulation) — since anti-VEGF alone is only temporizing.
Normal-Tension Glaucoma
Normal-tension glaucoma (NTG) is a form of glaucomatous optic neuropathy with characteristic optic disc and visual field damage occurring despite intraocular pressure in the statistically normal range, implying mechanisms beyond mechanical IOP stress. Primary vascular dysregulation is increasingly recognized as a central contributor in a substantial subset of patients. IOP reduction remains the only proven treatment, though vascular-targeted therapies are an active area of investigation for phenotypically selected patients.
Ocular Hypertension & Glaucoma Suspect
Ocular hypertension (elevated intraocular pressure without glaucomatous optic nerve or visual field damage) and glaucoma suspect status are common findings requiring individualized risk stratification rather than uniform treatment. The landmark Ocular Hypertension Treatment Study (OHTS) established that treatment roughly halves the 5-year conversion rate to glaucoma, and its risk model (refined and externally validated in more recent large cohorts) helps identify which patients benefit most from early treatment versus monitoring.
Ocular Motor Cranial Nerve Palsies (III, IV, VI)
Isolated palsies of the third, fourth, and sixth cranial nerves each produce a distinct, recognizable pattern of binocular diplopia and ocular misalignment, and localizing which nerve (and where along its course) is affected is the core skill in neuro-ophthalmic diplopia evaluation. The most urgent distinction to make is whether a third nerve palsy involves the pupil, since pupil involvement raises concern for a compressive, potentially aneurysmal lesion requiring emergent neuroimaging.
Ocular Myasthenia Gravis
Ocular myasthenia gravis is an autoimmune neuromuscular junction disorder producing fatigable ptosis and diplopia, and is a classic mimicker of nearly any pattern of ocular motility disturbance — sometimes called 'the great masquerader' of neuro-ophthalmology. Roughly half of patients eventually develop generalized disease, most often within two years, making the ocular-versus-generalized distinction and structured monitoring central to management.
Open-Angle Glaucoma
Open-angle glaucoma (OAG) is a chronic optic neuropathy characterized by progressive retinal ganglion cell loss and visual field defects in the setting of an open anterior chamber angle. Primary open-angle glaucoma (POAG) is the most common form, with related entities including normal-tension glaucoma and pseudoexfoliative glaucoma. Elevated intraocular pressure (IOP) is the major modifiable risk factor. Management focuses on IOP reduction through medical, laser, or surgical interventions to slow or halt disease progression.
Optic Neuritis
Optic neuritis is inflammatory demyelination of the optic nerve, classically presenting with subacute, painful monocular vision loss. The Optic Neuritis Treatment Trial established the foundational natural history and treatment framework, but optic neuritis is now understood to be biologically heterogeneous — multiple sclerosis-associated, MOG antibody-associated, and AQP4-antibody neuromyelitis optica spectrum disorder each have distinct imaging, laboratory, and prognostic profiles that change management and long-term monitoring.
Orbital Cellulitis
Orbital cellulitis is infection of the tissues posterior to the orbital septum, most often arising from contiguous spread of sinusitis, and is a sight- and life-threatening emergency distinct from the much more common and benign preseptal cellulitis. Diagnosis is primarily clinical but relies on contrast CT to identify complications such as subperiosteal or orbital abscess, and management requires early broad-spectrum antibiotics, ophthalmology involvement, and — for a substantial subset of patients — surgical drainage.
Orbital Fracture
Orbital fractures, most commonly involving the thin orbital floor ("blowout" fracture), result from blunt trauma transmitting force through the orbital contents to the weakest bony walls. Extraocular muscle entrapment is a surgical emergency, especially in children, where the "white-eyed blowout fracture" can present with dramatic restriction and pain despite minimal external signs; surgical repair within 24 hours of entrapment significantly improves ocular motility outcomes, while radiological criteria (defect size, tissue herniation, muscle involvement) guide the decision for surgery in less urgent adult cases.
Papilledema & Idiopathic Intracranial Hypertension
Papilledema is optic disc edema from raised intracranial pressure and is always bilateral, distinguishing it from other causes of disc swelling. Idiopathic intracranial hypertension (IIH) is its most common cause in young, overweight women of reproductive age, but papilledema always requires exclusion of a structural or vascular secondary cause before an idiopathic diagnosis is accepted. The IIH Treatment Trial established randomized evidence for acetazolamide plus weight loss as first-line therapy in mild visual loss.
Pediatric & Congenital Cataract
Pediatric cataracts are a rare but important, potentially treatable cause of childhood visual impairment, primarily through the mechanism of deprivation amblyopia. Modern genetic testing, evidence-based surgical timing, and improved intraoperative techniques (including combined posterior capsulectomy with anterior vitrectomy) have improved outcomes, though children left aphakic after early surgery require carefully individualized timing decisions balancing visual acuity against glaucoma risk.
Pediatric & Congenital Glaucoma
Pediatric glaucoma is a major, largely preventable cause of childhood blindness, most commonly caused by primary congenital glaucoma (isolated trabeculodysgenesis) or glaucoma associated with anterior segment dysgenesis syndromes such as Axenfeld-Rieger. Classic signs — epiphora, photophobia, blepharospasm, and corneal enlargement/clouding (buphthalmos) — should prompt urgent ophthalmology referral, since early surgical intervention (goniotomy or trabeculotomy) produces favorable outcomes and is the mainstay of treatment.
Pigmentary Glaucoma
Pigmentary glaucoma arises from pigment dispersion syndrome (PDS), in which posterior iris bowing causes mechanical rubbing against zonules, releasing pigment that deposits on the corneal endothelium (Krukenberg spindle), trabecular meshwork, and other anterior segment structures, eventually obstructing aqueous outflow. It classically affects young myopic men and can present with intermittent IOP spikes, sometimes after exercise. A proposed five-stage clinical gradation helps guide treatment, ranging from observation to laser iridotomy, trabeculoplasty, and incisional surgery.
Posterior Capsule Opacification
Posterior capsule opacification (PCO) is the most common late complication of cataract surgery, caused by residual lens epithelial cells migrating across and fibrosing the posterior capsule after phacoemulsification. Acute-onset PCO has become rare with modern square-edge intraocular lens design, but late-onset PCO remains common by 5-10 years postoperatively. Diagnosis is clinical, and treatment is a brief, effective outpatient Nd:YAG laser posterior capsulotomy.
Posterior Uveitis & Panuveitis: Overview
Posterior uveitis and panuveitis involve inflammation of the choroid, retina, and vitreous (posterior) or the entire uveal tract (panuveitis), with etiologies ranging from infectious (e.g., HTLV-1-associated uveitis) to autoimmune/systemic (sarcoidosis, Vogt-Koyanagi-Harada disease, Behçet's disease). These forms tend to have worse presenting visual acuity than anterior or intermediate uveitis and require etiology-directed treatment, since visual prognosis varies substantially by underlying cause.
Posterior Vitreous Detachment
Posterior vitreous detachment (PVD) is the age-related separation of the vitreous cortex from the retina, typically presenting with new flashes and floaters. Most PVDs are uncomplicated, but a minority are associated with retinal tears requiring urgent laser treatment to prevent retinal detachment; OCT findings such as persistent vitreopapillary or vitreomacular adhesion, and posterior vitreous opacities, help risk-stratify these patients.
Primary Angle-Closure Glaucoma
Primary angle-closure glaucoma (PACG) is a progressive optic neuropathy characterized by glaucomatous optic disc cupping and visual field loss secondary to elevated intraocular pressure (IOP) resulting from closure of the drainage angle. Angle closure occurs when the iris and trabecular meshwork come into appositional contact or adhesion, obstructing aqueous outflow. PACG is responsible for approximately half of glaucoma-related blindness worldwide and is most prevalent in Asia. Management focuses on IOP reduction, reopening closed angles, and preventing further closure through medical therapy, laser procedures, and surgical interventions including lens extraction.
Pseudoexfoliation Glaucoma
Pseudoexfoliation glaucoma is the most common identifiable cause of secondary open-angle glaucoma worldwide, arising from pseudoexfoliation syndrome — a multifactorial elastotic disorder depositing abnormal fibrillar material throughout the anterior segment and obstructing aqueous outflow. It carries a substantially higher risk of vision loss, more elevated and fluctuating IOP, and greater surgical complexity (from zonular weakness) than primary open-angle glaucoma, and often responds poorly to medical therapy alone.
Pterygium
Pterygium is a common, wing-shaped fibrovascular growth of conjunctival tissue onto the cornea, strongly associated with chronic ultraviolet light exposure. It is usually managed conservatively but may require surgical excision with conjunctival autografting for visually significant, rapidly growing, or persistently irritated lesions. Recurrence is the classically feared complication, though other complications such as conjunctival granuloma also occur.
Refractive Surgery: Overview
Refractive surgery encompasses corneal laser procedures (LASIK, PRK, SMILE) and lens-based procedures (implantable collamer lens, refractive lens exchange) used to reduce or eliminate dependence on spectacles or contact lenses. Technique selection depends on refractive error, corneal thickness and shape, pupil size, and patient-specific risk factors; implantable collamer lens implantation has shown particular advantages in optical quality for higher-risk corneal profiles, and combining laser correction with corneal crosslinking is an evolving strategy to reduce ectasia risk in susceptible eyes.
Retinal Detachment
Retinal detachment is a separation of the neurosensory retina from the retinal pigment epithelium, representing an ophthalmologic emergency requiring immediate surgical intervention. The most common form is rhegmatogenous retinal detachment, caused by fluid passing from the vitreous cavity into the subretinal space through retinal breaks, holes, or tears. Other forms include exudative and tractional detachment. Major risk factors include myopia, previous cataract surgery, retinal tears, and vitreous loss during intraocular procedures. Early recognition and prompt treatment are critical to preventing permanent visual loss, particularly when the macula is involved.
Retinal Vein Occlusion (CRVO & BRVO)
Retinal vein occlusion (RVO) — branch (BRVO) and central (CRVO) forms — is a common cause of vision loss from macular edema and, in ischemic cases, neovascular complications including neovascular glaucoma. BRVO is roughly four times more common than CRVO. Anti-VEGF therapy is the mainstay of treatment for macular edema, with laser photocoagulation and intravitreal corticosteroids as complementary options; anti-VEGF pretreatment before planned cataract surgery in RVO eyes reduces postoperative macular edema risk.
Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a genetically heterogeneous group of inherited retinal dystrophies causing progressive rod-then-cone photoreceptor degeneration, classically presenting with night blindness and progressive peripheral visual field loss. RP can occur in isolation or as part of a syndromic condition (e.g., Bardet-Biedl syndrome, Usher syndrome), and diagnosis increasingly relies on electroretinography, OCT, and genetic testing, with AI-assisted imaging analysis emerging as a tool to support diagnosis and monitoring.
Retinopathy of Prematurity (ROP)
Retinopathy of prematurity (ROP) is a vasoproliferative retinal disease of preterm, low-birth-weight infants driven by disrupted normal retinal vascularization, ranging from mild disease that regresses spontaneously to severe disease threatening retinal detachment and blindness. Anti-VEGF therapy, laser photocoagulation, and vitrectomy each have distinct roles and long-term refractive consequences, making structured screening and staged, risk-adapted treatment essential.
Steroid-Induced Glaucoma
Steroid-induced glaucoma is a form of secondary open-angle glaucoma resulting from corticosteroid-induced ocular hypertension, most often from topical or intravitreal steroid exposure. Approximately 40% of the general population develops elevated intraocular pressure after steroid exposure and about 6% develop frank glaucoma, but nearly all patients with primary open-angle glaucoma are steroid responders. It is usually reversible if recognized and treatment duration is under a year, but prolonged, unrecognized exposure can cause permanent vision loss.
Strabismus: Esotropia & Exotropia
Strabismus (ocular misalignment) is broadly classified by direction (esotropia, inward; exotropia, outward) and by whether the deviation is present at all fixation distances or only some (e.g., partially accommodative esotropia). Management ranges from spectacle correction and orthoptic exercises to botulinum toxin and strabismus surgery, and early treatment of amblyogenic strabismus in children is critical to preserving binocular vision and preventing permanent visual loss.
Thyroid Eye Disease
Thyroid eye disease (TED, also called Graves' orbitopathy) is an immune-mediated orbital disorder most commonly associated with Graves' hyperthyroidism, presenting with proptosis, lid retraction, diplopia, and, in severe cases, vision-threatening optic neuropathy. Staging activity and severity with tools like the Clinical Activity Score and EUGOGO categories guides management, which ranges from risk-factor modification and observation in mild disease to high-dose intravenous glucocorticoids, targeted biologic therapy (teprotumumab), and urgent orbital decompression in sight-threatening disease.
Traumatic Cataract
Traumatic cataract results from blunt or penetrating ocular injury disrupting the lens capsule or fiber architecture, and can present acutely or develop over time after the initial trauma. Surgical outcomes are generally favorable with individualized planning, though intraoperative and postoperative complication rates remain considerable, and associated injuries (especially in open-globe trauma) are major independent predictors of final visual outcome.