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Explain easy words to prepare next day class test
Here's a clear, easy-to-understand summary of everything in your notes on Primary Angle-Closure Disease (PACD) - perfect for a next-day class test!
🔵 PRIMARY ANGLE-CLOSURE DISEASE (PACD) - Simple Study Notes
1. WHAT IS IT? (Definition)
Think of the eye like a sink. Water (aqueous humor) is always being made inside the eye. It drains out through a tiny "drain" called the trabecular meshwork (TM) at the angle between the iris (colored part) and cornea.
In PACD, the iris gets pushed/pulled against this drain, blocking it → pressure builds up inside the eye (raised IOP).
- Simple rule: Narrow angle + iris blocks drain = angle closure disease
- It has no other eye or body disease causing it (that's what "primary" means)
- New name: "PACD" replaced "primary angle-closure glaucoma" because "glaucoma" is only used when the optic nerve AND visual fields are damaged
2. WHO GETS IT? (Epidemiology)
| Group | Details |
|---|---|
| Age | Most common in 60s-70s (6th and 7th decade) |
| Gender | More in females (M:F = 1:3) |
| Race | Most common in Mongolians, South-East Asians, Chinese, Eskimos; rare in Blacks |
| Indians | POAG : PACD ratio = 1:1 |
| Mongolians | POAG : PACD ratio = 1:3 |
- Chronic (silent) form is 3x more common than acute form (most people don't know they have it!)
- PACG is the major cause of glaucoma blindness worldwide
3. WHY DOES IT HAPPEN? (Etiopathogenesis)
A. Risk Factors (Who is prone?)
Anatomical features that make someone prone:
- Hypermetropic (far-sighted) eyes - small eyes with shallow front chamber
- Iris-lens diaphragm placed more forward than normal
- Narrow angle due to small eyeball, big lens, small cornea
- Plateau iris configuration - the ciliary body pushes iris forward
- Family history (heredity plays a role)
B. Three Mechanisms of Raised IOP
1. Pupillary Block (MOST COMMON - 70%)
- Step-by-step: Pupil dilates mid-way → iris presses against lens → fluid builds behind iris → iris balloons forward (called "Iris Bombe") → blocks the angle drain
- Triggers (what makes pupil dilate):
- Reading in dim light, cinema/TV in dark room (physiological mydriasis)
- Eye drops like atropine, phenylephrine, tropicamide (pharmacological mydriasis)
- Stress, anxiety, antidepressants, bronchodilators, nasal decongestants
2. Plateau Iris Configuration (10% - atypical)
- Ciliary body pushes iris forward mechanically, even without pupillary block
- On gonioscopy: characteristic "double hump sign" is seen
- No pupil block here - angle just gets pushed shut
- Treatment: Miotics + laser peripheral iridoplasty
3. Phacomorphic Mechanism
- Abnormal/swollen lens pushes iris forward or causes pupillary block
- Basis for lens extraction as treatment in some cases
4. CLASSIFICATION
New ISGEO Classification (2006):
- PACS - Primary Angle Closure Suspect (angle at risk, no damage yet)
- PAC - Primary Angle Closure (angle closed, IOP raised but no optic nerve damage)
- PACG - Primary Angle Closure Glaucoma (angle closed + optic nerve damaged + visual field loss)
Old Conventional Classification:
- Latent (occludable angle)
- Subacute (intermittent attacks)
- Acute (emergency)
- Chronic
5. CLINICAL STAGES
Stage 1: PAC Suspect (PACS)
- No symptoms at all
- Found accidentally during routine eye check
- Signs: eclipse sign (shadow on nasal side when light shone from temporal side), shallow anterior chamber
- Van Herick grading of angle:
- Grade 4 = Wide open (normal)
- Grade 0 = Closed (dangerous)
- Management: Periodic follow-up; provocative tests (prone-darkroom test or mydriatic test) - IOP rise >8 mmHg = positive
Stage 2: Acute PAC - THE EMERGENCY ⚠️
Signs (easy to remember):
- Red, painful eye
- Cornea - cloudy/hazy (edematous)
- Pupil - semi-dilated, oval, fixed (doesn't react to light)
- IOP - very HIGH (40-70 mmHg normally)
- Anterior chamber - very shallow
- Optic disc - swollen and red
Diagnosis: Usually obvious from clinical features
Differentials to rule out:
- Acute conjunctivitis
- Acute iridocyclitis
- Phacomorphic/neovascular glaucoma
Management of Acute PAC Attack
Step 1 - Bring IOP down immediately (if IOP >40 mmHg):
- IV Mannitol 1 gm/kg body weight (if patient is vomiting)
- Oral Glycerol 1 gm/kg in lemon juice (if patient tolerates orally)
- Acetazolamide 500 mg IV, then 250 mg 3x/day (carbonic anhydrase inhibitor)
- Topical drops: Beta-blocker (timolol 0.5%), Alpha agonist (brimonidine 0.1-0.2%), Prostaglandin analogue (latanoprost)
- Pilocarpine 2% - start only after 1 hour (not at very high IOP because sphincter is ischemic and won't respond)
- Topical steroids (prednisolone/dexamethasone) to reduce inflammation
- Analgesics + antiemetics for pain/vomiting
Step 2 - Definitive Treatment:
- Laser Peripheral Iridotomy (LPI) using Nd:YAG laser - creates a hole in the iris to bypass the pupillary block. Done at 11 o'clock or 1 o'clock position on iris
Step 3 - Prevent attack in the other (fellow) eye:
- Prophylactic laser iridotomy in the fellow eye (50% chance of attack in that eye too!)
Step 4 - Long-term surveillance of both eyes
Vogt's Triad (seen after acute PAC attack):
- Glaukomflecken (white spots on lens - anterior subcapsular opacity)
- Patches of iris atrophy
- Slightly dilated, non-reacting pupil
Stage 3: Primary Angle-Closure Glaucoma (PACG)
- Chronic, silent, no pain
- IOP constantly elevated
- Optic disc cupping (same as POAG)
- Visual field defects (like POAG)
- Gonioscopy: >270° of angle closed + peripheral anterior synechiae (PAS)
- White, painless eye
- Treatment: Laser iridotomy first → if fails → Trabeculectomy
6. KEY HIGH-YIELD POINTS FOR TEST
| Topic | Remember |
|---|---|
| Most common mechanism | Pupillary block (70%) |
| Most common in | Asian/Mongolian women in 60s |
| Iris Bombe | Iris balloons forward due to fluid buildup behind it |
| IOP in acute attack | 40-70 mmHg |
| Pupil in acute attack | Semi-dilated, vertically oval, fixed |
| First drug if IOP >40 | IV Mannitol |
| Pilocarpine timing | Start AFTER 1 hour of IOP lowering |
| Definitive treatment | Laser Peripheral Iridotomy (LPI) |
| Double hump sign | Plateau iris configuration on gonioscopy |
| Vogt's triad | Glaukomflecken + iris atrophy + dilated fixed pupil |
| PACS management | Periodic follow-up only; no surgery unless confirmed |
| Fellow eye prophylaxis | LPI (50% risk of acute attack) |
Good luck in your test tomorrow! The most important topics likely to be asked are: mechanism of pupillary block, signs of acute PAC, management steps, and the ISGEO classification.
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