Refractive Errors Flashcards
Refractive power of eyeball
+60(58.6)
What is near reflex or accommodation triad?
- Convergence of eyeballs by medial rectus
- Miosis by sphincter pupillae
- Accomodation by ciliary muscles-increase in Anterior curvature of lens.
Types of Myopia
- Axial-Path,Buphth,post staph
- Index-nuclear cataract
- Positional-ant dislocation/subluxation nd Weil march
- Curvatural-corneal or lens
Symptoms of myopia
- Defective far vision/near sightedness
2. Floaters(muscae volitantes)
Signs of eye in myopia
- Large eyeball-blue thin sclera
- Cornea-large
- AC-deep
- Exophoria
What is fundus?
View of all structures in the post segment 1.vitreous nd retina transparent 2.Choroid(red)
*viewed with ophthalmoscope.
Fundus signs in myopia
- Myopic temporal crescent around optic disc
- Optic disc tilted
- Lacquer cracks
- Foster fuch’s spots
- Posterior staphyloma
Overall appearance of fundus in myopia
Tessellated or Tigroid appearance d/t diffuse alterations in RPE
Other retinal findings in myopia
- Lattice degeneration
- Rhegmatogenous RD
- Retinal tears
- Vitreous deatchment - Seen as WEISS rings
Complications of path myopia
- RD
- Complicated cataract-post subcapsular
- Vitreous hmg nd choroid also hmg
- PAOG- more like an association
- Strabismus fixes convergence
Fundus signs nd complications are absent in?
Simple or developmental myopia
What are the zones of chorioretinal atrophy
2 zones:
- Alpha-always seen in glaucoma
- Beta-TMC
Laser surgeries in myopia
- Corneal based
- Radial keratotomy
- PRK with excimer laser
- LASIK with excimer or femto(upto -8₹
- Smile(upto -10D)
- Lens based
- Clear lens extraction-Fucala sx (for >-12D)
- ICL
Types of Hypermetropia
- Axial-Newborn,micro,nano
- Index-cortical sclerosis
- Positional-post dislocation
- Curvatural-cornea plana
- Aphakia
- Overcorrected Myopia in refractive Sx or Undercorrected IOL in cataract Sx
Symptoms of Hmt
- Defective near vision
2. Asthenopic symptoms(over active near reflex)