DISEASES OF THE LENS.ppt bagggggbhggggggg

Lens

1. DISEASES OF LENS
-A Lens is packed with transparent cells enclosed in
capsule
-It’s suspended in position by suspensory ligament or
zonules
-It’s continues to growth throughout life, new fibres
formed just beneath the capsule
And older fibres compacted at the centre.
-The lens provides 1/5 of focusing power.

2. Changes in the lens
-Increase in hardness- it becomes hard with age and
this affects accommodation hence difficulty to
focusing on near objects
-Increase in density
-Increase in size
Classification of lens diseases
Cataracts
Subluxation and dislocation

3. Cataract
- Is opacity of the lens?
Classification of lens opacities
-Cortical lens opacities
-Nuclear sclerosis
-Posterior capsule cataract

4. Causes of cataracts
•Age/Senile cataract
•Metabolic DM, hypoparathyroidism
•Other systemic diseases
-Chronic renal failure
•Trauma - perforating
-Blunt trauma
•Intraocular Infections – uveitis
•Radiations –radiotherapy, infrared at furnances
•Drugs like CPZ, steroids,miotics
•Congenital cataracts

5. •Prevalence of cataracts
•Cataract is very common disease in all communities
•Especially in elderly people
•Half of patients present with cataracts as cause
blindness
•Cataracts are common and occur at an earlier age in
hot, tropical climates
•Possible theories
•Episodes of severe dehydration
•Solar radiation
•Diet deficiency in vitamin c
•Heat

6. •Symptoms of cataract
•-Progressive loss of vision
•-Painless
•Glear
•-Multiple images or ghost images
•-Refractive changes
•Nuclear sclerosis-myopia
•Dense Cortex – hypermentropia
•White pupil appearence

10. •Evaluation of cataract
•Coaxial illumination- Shadows in red reflex.
•Dilate the pupil
•-Cortical lens opacity-outer layer develops opacities
• Opacities radiate from the centre like spokes
•-Nuclear sclerosis
•Nucleus –yellow brown, black
•In mature nuclear cataract the red reflex is absent.
•-Posterior subcapsular cataract lens opacities,
patients are young
• Coaxial illumination seen as a grey shadow against
the red reflex

11. •Assessment of a cataract patient for operation
•If any red reflex is present Va is CF or better
•If Va improves with pin hole, not spectacles there
is no macular disease
•Pupillary reflex
•Light projection
•Intraocular pressure
•NB.4P. pin hole, pupil, projection and IOP

12. complication of cataracts
-Intumescent lens or hyper-mature cataract
- Acute angle closure glaucoma
- Phacolytic uveitis and glaucoma
 

13. Congenital cataract
Causes
-Infections (Torches)
- Rubella/german measles chorioretinitis
Deafness and heart defects
-Toxoplasmosis –chorioretinitis/cataract,
- CMV
-Anoxic trauma to fetus at birth or before
-Genetic - galactosaemia

16. PRE-OPERATIVE AND INTRAOPERATIVE PRECEDURES
-VA
-Biomentry& Keratomentry
- Pupil dilation with short acting mydriatics
-Povidine iodine drops applied in conjuctival sac
- Retrobulbar/Subtenon injection of lidocaine
-Intracameral injection of ceftriaxone at end of operation
-Subconjuctival injection of dexamethosone-gentamycin
at end of operation
-Padding the eye 24 HOURS

17. Management of cataract
1.Intracapsular cataract extraction ( ICCE)
-+10 spectacles
- anterior chamber lens
- Contact lens wear
2.Extracapsular cataract extraction (ECCE +PC IOL)
3.Small incision cataract extration(SIC+ PC IOL)
4.Phaco emulsification(PHACO+PC IOL)
5.Traditional method couching

18. Complications
-Expulsive haemorrhage
- Endophthalmitis -48hrs
-Iris prolapse
-Wound leak
-Hyphema- bleeding in anteria chamber.
-Corneal oedema/striate keratopathy
- RD
-

19. - Bullous keratopathy
-Thickening of the posterior capsule
-Posterior capsule rupture/vitreous loss
-Aphakia –lens removed
-Malposition of intraocular lens
-Astigmatism-

22. Other diseases
•Subluxation caused by partial rupture of the
suspensory ligament
•Dislocation caused by total rupture of suspensory
ligament

24. •Causes of sublaxation and dislocation.oiu
•Injury especially blunt
•Hypermature cataracts
•Congenital weakness
• -Marfan’s syndrome. Tall patients with long
extremities, high palate, cardiac abnormalities.
• -Homocystinuria metabolic disorder with
mental deficiency
• -Marcheani’s syndrome short stature
patients
•