Keratoconus
1. Definition
- โรคของกระจกตาแบบ noninflammatory ectasia
- มีลักษณะ corneal thinning + cone-shaped protrusion
→ ทำให้เกิด irregular astigmatism + visual impairment
2. Epidemiology
- เริ่มช่วง puberty →
early adulthood
- progression
ถึง ~40 ปี
- prevalence
~50–230/100,000
3. Risk Factors
3.1 Systemic
- Down
syndrome
- Ehlers-Danlos
- osteogenesis
imperfecta
3.2 Environmental
- atopy
/ asthma
- eye
rubbing (สำคัญมาก)
3.3 Genetic
- family
history (~6–8%)
4. Pathophysiology
- ↓ corneal collagen strength
- structural
weakening → thinning → protrusion
- อาจมี inflammatory component
5. Clinical Presentation
5.1 Early
- blurred
vision
- frequent
change glasses
- myopia
+ astigmatism เพิ่ม
5.2 Progressive
- irregular
astigmatism
- contact
lens fitting ยาก
5.3 Advanced signs
|
Sign |
Description |
|
Fleischer ring |
iron deposition |
|
Vogt striae |
stress lines |
|
Munson sign |
V-shape lower lid |
|
corneal thinning |
central/inferior |
5.4 Complication (สำคัญ 🚨)
- Corneal
hydrops
- acute
pain + ↓ vision
- จาก Descemet tear
6. Diagnosis
6.1 Clinical suspicion
- VA
correct ไม่ได้
- progressive
astigmatism
6.2 Investigation
- keratometry
→ irregular mires
- corneal
topography (gold standard)
7. Differential Diagnosis
- progressive
myopia
- pellucid
marginal degeneration
- keratoglobus
8. Management
8.1 Early disease
- spectacles
8.2 Moderate
- Rigid
gas-permeable lens (RGP)
→ correct irregular cornea
8.3 Advanced optical correction
- scleral
lens
- hybrid
lens
8.4 Disease-modifying treatment
⭐ Corneal cross-linking (CXL)
- riboflavin
+ UV
- ↑ collagen strength
- goal
= stop progression (ไม่ใช่ improve vision)
👉 indication: progressive
disease
8.5 Surgical
Intrastromal ring
- flatten
cornea
Keratoplasty (10–15%)
- penetrating
keratoplasty
- DALK
8.6 Corneal hydrops management
- conservative
(2–4 เดือน)
- cycloplegic
+ hyperosmotic
- ↓ edema
9. Prognosis
- progressive
disease
- risk
progression ↑ ใน
- young
age
- steep
cornea
👉 CXL ช่วยลด
need transplant
10. Clinical Pearls
- progressive
astigmatism = think keratoconus
- eye
rubbing = modifiable risk สำคัญ
- CXL
= standard ใน early progressive disease
- hydrops
= acute complication ต้องรู้จัก
- contact
lens fitting difficulty = clue
11. Practical Approach
Young patient + blurred vision
👉 Step 1: suspect
- progressive
astigmatism
👉 Step 2: confirm
- corneal
topography
👉 Step 3: treat
- early
→ glasses
- moderate
→ RGP
- progressive
→ CXL
👉 Step 4: refer
- ophthalmology
ไม่มีความคิดเห็น:
แสดงความคิดเห็น