Cataract

Anatomy & Pathophysiology

Classification

1. Age-Related (Most Common)

Posterior Subcapsular Cataract (PSC)

• Located just in front of the posterior capsule
• Granular or plaque-like on slit lamp; black and vacuolated on retroillumination
• Vacuoles are swollen "bladder" (Wedl) cells - migratory lens epithelial cells
• Because it sits at the nodal point of the eye, it has a disproportionately severe effect on vision
• Characteristic symptom: glare from car headlights; worsens with miosis (near tasks, bright light)

Anterior Subcapsular Cataract

• Lies directly under the lens capsule
• Associated with fibrous metaplasia of the lens epithelium

Nuclear Sclerotic Cataract

• Exaggeration of normal aging
• Yellowish hue due to deposition of urochrome pigment
• Associated with myopia (index myopia) - "second sight"
• Advanced cases: brown nucleus (brunescent); rarely black (cataracta nigra)
• Best assessed with oblique slit-lamp beam

Cortical Cataract

• Involves anterior, posterior, or equatorial cortex
• Starts as clefts and vacuoles between lens fibers due to cortical hydration
• Typical cuneiform (wedge-shaped) or radial spoke-like opacities
• Often begins in the inferonasal quadrant
• Glare is a common symptom

2. Cataract Maturity

3. Congenital Cataract

• Present at birth or developing in early childhood
• Can be isolated or associated with systemic conditions (Down syndrome, galactosemia, rubella, TORCH infections)
• Must be treated promptly to prevent amblyopia

4. Secondary (Complicated) Cataract

• Chronic anterior uveitis - most common cause; posterior and anterior opacities; steroids also contribute
• Acute angle-closure glaucoma - glaukomflecken (small grey-white subcapsular opacities, focal lens epithelial infarcts); pathognomonic of previous acute attack
• High myopia - posterior subcapsular opacity and early nuclear sclerosis

5. Cataract in Systemic Disease

6. Drug-Induced

• Steroids (systemic or topical): posterior subcapsular cataract
• Phenothiazines, amiodarone, miotics (long-term)

7. Traumatic

• Blunt trauma: rosette-shaped PSC
• Penetrating injury: direct cortical opacification
• Electric shock, radiation, infrared (glassblower's cataract)

Symptoms

• Reduced visual acuity (initially correctable with spectacles)
• Loss of contrast sensitivity
• Altered colour perception - particularly impaired blue perception
• Glare and haloes (especially at night - headlight glare)
• Monocular diplopia (especially with point light sources)
• Difficulty in low-light conditions
• Nuclear cataract: myopic shift ("second sight")

Diagnosis

• Slit-lamp examination: gold standard - type, location, density
• Retroillumination: best for PSC and cortical opacities
• Visual acuity testing: Snellen chart
• Contrast sensitivity testing
• Potential acuity meter (PAM): estimates post-op visual potential
• B-scan ultrasound: when fundus view is obscured

Treatment

Conservative

• Spectacle correction for mild cases
• Increased illumination for reading

Surgical (Definitive)

• Small incision (2-3 mm)
• Ultrasonic fragmentation and aspiration of lens nucleus
• Foldable intraocular lens (IOL) implanted into the capsular bag
• Outpatient procedure
• Results equivalent to femtosecond laser-assisted cataract surgery (FLACS) for standard cases

• Laser performs capsulorrhexis, lens fragmentation, and corneal incisions
• No clear superiority over phacoemulsification in standard cases

Intraocular Lens (IOL) Options

• Monofocal IOL: single focus point (usually distance)
• Multifocal/trifocal IOL: near and distance vision
• Toric IOL: corrects pre-existing astigmatism
• Extended depth of focus (EDOF) IOL

Surgical Timing

• In general, the worse eye is operated on first
• The second eye is operated on as its cataract worsens and monocularity becomes a functional issue
• In children with congenital cataract: surgery within weeks of birth to prevent amblyopia, followed by aggressive amblyopia treatment

Complications of Surgery

• Posterior capsule opacification (PCO) - "after-cataract": most common late complication; lens epithelial cells migrate onto the posterior capsule; treated with Nd:YAG laser posterior capsulotomy
• Endophthalmitis: rare but serious infection
• Cystoid macular edema (CME)
• Retinal detachment: increased risk in high myopes
• Corneal decompensation (bullous keratopathy)
• Dry eye post-surgery (recent systematic review 2025, PMID 39806338 confirms this as a significant complication)
• Dropped nucleus (posterior dislocation of lens fragments)
• Posterior capsule rupture

Prognosis

Upper GI Endoscopy (Esophagogastroduodenoscopy / EGD / OGD) - Indications

DIAGNOSTIC INDICATIONS

Symptoms / Clinical Presentations

Bleeding

• Acute upper GI bleeding (hematemesis, melena, coffee-ground vomiting) - both diagnostic and therapeutic; EGD within 24 hours (within 12 h in high-risk patients)
• Occult bleeding / iron deficiency anemia - chronic blood loss from ulcers, angiodysplasia, tumors
• Presumed chronic GI blood loss - e.g., positive fecal occult blood test

Radiology / Other Investigations

• Abnormal barium swallow / meal findings (ulcer, mass, stenosis) - for confirmation and biopsy
• High-risk findings on CT scan requiring tissue sampling

Screening & Surveillance

• Barrett esophagus - surveillance for dysplastic progression to adenocarcinoma
• Gastric ulcer - repeat endoscopy at 6-8 weeks to confirm healing and exclude malignancy
• Pernicious anemia - surveillance for gastric cancer (associated with chronic atrophic gastritis)
• Previous gastrectomy - remnant stomach surveillance for anastomotic malignancy
• Esophageal varices screening - in patients with known portal hypertension / cirrhosis
• Genetic syndromes predisposing to GI malignancy (e.g., familial adenomatous polyposis, hereditary diffuse gastric cancer, Lynch syndrome)
• Celiac disease confirmation - duodenal biopsy for villous atrophy

Caustic / Toxic Ingestion

• Caustic ingestion (acids, alkalis) - to assess acute mucosal injury; guides management (performed 12-24 h after ingestion, never in the immediate acute phase)
• Foreign body ingestion - assessment before removal

Pre-operative Assessment

• Patients with a history of ulcer or GI bleeding scheduled for organ transplantation, major surgery, long-term anticoagulation, or long-term NSAID therapy

Tissue Sampling

• Mucosal biopsy for histology (cancer, H. pylori, celiac, IBD)
• Rapid urease test (CLO test) for H. pylori detection
• Brushings for cytology
• Aspirates for microbiological culture

THERAPEUTIC INDICATIONS

1. Control of GI Bleeding

• Peptic ulcer bleeding - injection therapy (adrenaline), heater probe, electrocoagulation (bipolar/monopolar), hemoclip application, laser photocoagulation
• Variceal bleeding - band ligation (preferred) or sclerotherapy for esophageal varices; glue injection for gastric varices
• Angiodysplasia / vascular malformations - argon plasma coagulation (APC), electrocoagulation
• Dieulafoy lesion - hemostasis

2. Stricture Dilation

• Benign esophageal strictures (peptic, post-anastomotic, caustic, radiation-induced) - balloon dilation (through-the-scope / TTS) or bougie dilators (Savary-Gilliard)
• Pyloric stricture - balloon dilation under direct vision
• Achalasia - pneumatic balloon dilation; or botulinum toxin injection; or per-oral endoscopic myotomy (POEM)

3. Foreign Body Removal

• Ingested foreign bodies impacted in esophagus or stomach (coins, batteries, bones, food bolus)
• Button batteries - emergency removal (caustic injury within hours)

4. Tumor Management

• Endoscopic mucosal resection (EMR) - early esophageal / gastric cancer, large polyps
• Endoscopic submucosal dissection (ESD) - en-bloc resection of early mucosal neoplasia
• Ablation of Barrett esophagus with dysplasia (radiofrequency ablation, cryotherapy)
• Stenting of malignant strictures - self-expanding metal stents for palliative treatment of obstructing tumors of the esophagus, stomach, or duodenum

5. Feeding / Drainage Tube Placement

• Percutaneous Endoscopic Gastrostomy (PEG) - long-term enteral nutrition (stroke, head & neck cancer, neurological disease)
• Percutaneous Endoscopic Jejunostomy (PEJ) - when gastric feeding not possible
• Nasojejunal tube placement - short-term post-pyloric feeding

6. Polyp Removal

• Gastric polyps (hyperplastic, adenomatous)
• Duodenal adenomas (especially in FAP)

7. Advanced / Third-Space Endoscopy

• POEM (Per-Oral Endoscopic Myotomy) - achalasia, Zenker diverticulum, gastroparesis
• Endoscopic submucosal tunneling resection - subepithelial tumors (GISTs, leiomyomas)
• Endoscopic ultrasound (EUS)-guided drainage - pancreatic cysts, walled-off necrosis, biliary access

CONTRAINDICATIONS

Absolute

• Patient refuses or cannot give consent
• Known or suspected perforated viscus (free air)
• Severely hemodynamically unstable patient unable to tolerate any procedure

Relative

• Functional symptoms without alarm features (IBS-like)
• Medically unstable / unable to tolerate sedation
• Benign radiographic findings (e.g., uncomplicated sliding hiatal hernia)
• Recent GI anastomosis (risk of disruption)
• Severe cervical spine instability
• Suspected Zenker diverticulum (risk of inadvertent cannulation)
• Patient on anticoagulation - requires careful risk stratification per BSG/ESGE 2021 guidelines

Summary Table

Purposes of Upper GI Endoscopy (EGD/OGD)

1. DIAGNOSTIC PURPOSE

• Identify the cause of symptoms - dysphagia, heartburn, epigastric pain, nausea/vomiting, weight loss
• Locate the source of bleeding - find the bleeding ulcer, varix, or vascular lesion causing hematemesis or melena
• Obtain tissue samples - mucosal biopsy for histology, H. pylori urease test (CLO test), cytology brushings
• Assess caustic / toxic injury - grade the mucosal damage after acid/alkali ingestion
• Confirm or clarify abnormal radiology - follow up on suspicious findings from barium studies or CT scans

2. THERAPEUTIC PURPOSE

3. SURVEILLANCE & SCREENING PURPOSE

• Barrett esophagus - regular surveillance to detect dysplasia before cancer develops
• Esophageal varices - screening in all cirrhosis patients; surveillance after treatment
• Gastric ulcer - repeat endoscopy at 6-8 weeks to confirm healing and exclude malignancy
• Pernicious anemia / chronic atrophic gastritis - surveillance for gastric cancer
• Post-gastrectomy stomach - watch for anastomotic or remnant malignancy
• High-risk genetic syndromes - FAP, hereditary diffuse gastric cancer, Lynch syndrome

In One Line Per Purpose

Complications of Upper GI Endoscopy (EGD/OGD)

GENERAL CLASSIFICATION

1. Procedure-related (from the scope and endoscopic actions)
2. Sedation-related (from conscious/deep sedation)
3. Procedure-specific (from particular therapeutic interventions)

1. PERFORATION

• Incidence (diagnostic EGD): < 0.1% (less than 1 in 1,000)
• Sites: Pharynx/hypopharynx (cricopharyngeal area - most common during blind intubation), esophagus, stomach, duodenum
• High-risk situations:
  • Zenker's diverticulum (inadvertent cannulation)
  • Cervical osteophytes
  • Tight strictures
  • Post-radiation or post-surgical anatomy
• Perforation rates rise sharply with therapeutic procedures:

• Management: Early recognition is key. Small contained perforations may be managed endoscopically (clip closure) or conservatively; large perforations require urgent surgical repair.

2. BLEEDING

• Causes:
  • Mucosal trauma during intubation
  • Biopsy sites
  • Polypectomy (post-polypectomy bleeding)
  • Variceal band ligation (early ulcer bleeding after band sloughing)
  • Post-sphincterotomy (ERCP)
• Risk increased by: Thrombocytopenia, coagulopathy, anticoagulant or antiplatelet use
• Note: Diagnostic endoscopy with biopsy is generally safe even on aspirin or oral anticoagulants. High-risk therapeutic procedures (EMR, ESD, variceal banding, dilation) require anticoagulant management per ASGE/ESGE/BSG guidelines.

3. CARDIOPULMONARY COMPLICATIONS (Most Common Overall)

4. INFECTION

• Bacteremia: Transient bacteremia can occur during endoscopy, especially with therapeutic procedures; rarely clinically significant in healthy patients
• Infective endocarditis: Very rare; antibiotic prophylaxis is only recommended for high-risk cardiac patients (prosthetic valves, previous IE, congenital heart disease) undergoing endoscopy with an active GI/biliary infection
• Transmission of infection via inadequately disinfected endoscopes (very rare with modern reprocessing protocols)
• Peritonitis / abscess following PEG tube placement (buried bumper syndrome, site infection)

5. COMPLICATIONS SPECIFIC TO THERAPEUTIC PROCEDURES

6. MISCELLANEOUS / OTHER COMPLICATIONS

• Dental injury - teeth or dental prostheses damaged during scope insertion
• Pharyngeal / throat trauma - sore throat, hoarseness (very common, usually minor)
• Neck hematoma / retropharyngeal injury - rare, from difficult intubation
• Mallory-Weiss tear - mucosal laceration at gastro-esophageal junction from retching
• Inadequate examination / missed diagnosis - technical failure to visualize gastric cardia/fundus without retroflexion; inadequate views of ampulla with standard forward-viewing scope
• Air embolism - extremely rare; reported with high-flow CO₂ or air insufflation
• Medication errors - incorrect sedation doses

RISK FACTORS FOR COMPLICATIONS

SUMMARY TABLE