corneal diseases
TRANSCRIPT
Corneal Disease
Lecturer: Miss.Yumna Tariq M.Phil. Scholar ( Optom)
Congenital abnormalities of cornea1. Microcornea:• a congenital condition• the corneal diameter is <10 mm (or <9 mm in
newborns). • Unilater or bilateral• It is believed to arise due to arrest of growth of the
cornea in the 5th gestational month.• Hypermetropic
2.Megalocornea:• Large corneal diameter > 13mm• Bilateral• Usually X-linked• 90% of the affected individuals are Males• High Myopia and Astigmatism
Megalocornea
c. Cornea Plana:Severe decrease in corneal curvature resulting in reduced refractive power of the cornea ( 20D – 30D)• Rare• Bilateral• Hypermetropia
Normal cornea vs cornea plana
Corneal ectasias:Ectasia: • an enlargement, dilation, or ballooning effect
Corneal ectasia?• are a group of uncommon, noninflammatory, eye disorders
characterised by• bilateral thinning of the central, paracentral, or peripheral
cornea
• Most common1. Keratoconus2. Keratoglubous3. Pellucid marginal degeneration
1.Keratoconus:
• a progressive, non- inflammatory,• bilateral, asymmetric disease• characterized by paraxial stromal thinning and weakening
that leads to corneal surface distortion.• Onset = around puberty, slow progression thereafter until
the 3rd & 4th decades of life• Role of heredity?• Most pts. do not have positive family Hx.
Presentation:
1. Reduce visual Acuity2. Frequent changes in spectacle prescription3. Glare4. Ghost images5. Monocular Diplopia
Signs:1. Progressive myopia and irregular astigmatism2. Rizzuti sign -------> conical reflection on the nasal cornea when
a penlight is shone from the temporal side3. Munson sign --------> bulging of Lower Eyelid in Down Gaze4. Oil droplet reflex -------> by Direct Ophthalmoscopy5. Scissor Reflex --------> Retinoscopy6. Bowmans scarring ------- > due to previous hydrops7. Stromal vertical, fine lines (Vogt Straie) --------> Slit Lamp8. Epithelial Iron deposits ( Fleischer Ring) ----> S/L cobalt blue
filter9. Apical Scarring ------> at the apex of the cone10. Acute hydrops ----> rapture in Descmet’s membrane 11. Prominent corneal Nerves
External Signs:
Slit Lamp findings:
Retro illumination sign
Munson sign & Rizzuti Sign:
&
Scissor reflex & oil droplet reflex
&
Fleischer ring & Vogt Straie:
&
Hydrops & Corneal Nerves
&
Detection of Keratoconus:1.Retinoscopy2. Slit lamp3. Keratometer4. Corneal Topography
CLASSIFICATION OF KERATOCONUS
Classification based on shape of Cone:
• Nipple Shape:
small diameter ( 5mm)
round shape
Easiest to fit with CL
• Oval Cones: Large dia ( > 5mm)
Often displaced inferiorly
More difficult to fit wit Cl
• Globus Cones: Largest Dia ( >6mm)
75% of the total cornea is affected
Most difficult to fit with lenses
ON THE BASIS OF Keratometer Reading:
Grades of Keratoconus:
• Mild K ( < 48 D)• Moderate K ( 48D – 54D)• Severe K ( > 54D )
Associations:
Systemic:• Downs Syndrome• Marfan’s Syndrome• Turner syndrome • Ehlers- Danlos Syndrom etcOcular :• Persistent Eye rubbing• Aniridia• Retinitis pigmentosa
Treatment:• Spectacles:• RGP ( Rigid Gas Permeable Contact Lenses)• Keratoplasty
2. Keratoglobus:
“the condition in which the entire cornea is abnormally thin”
Or Generalized thinning of cornea
Onset: at birthSigns: ectasia is Generalized acute hydrops occur less commonly Cornea is more prone to rupture on traumaManagement: • CL ------ scleral CL• Surgery ------poor results
3.Pellucid marginal degeneration:
• Inferior corneal thinning ( sometimes superior cornea too)• Bilateral• Onset: 20 years to 40 years• Cresent shape band of inferior cornea extending from 4 – 8 o’clock• Intact epithelium • No fleischer rings, no Vogt straie• High Astigmatism ( against the rule)
Treatment:Spectacles: not usefullCL: RGP CLSurgery: keratoplasty
Thanks.