cataract and refractive surgery

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Lecture from RCSI

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  • 1. CATARACT AND REFRACTIVE SURGERY Ms. A. Bobart Hone 2009

2. CATARACT The term CATARACT denotes any opacity of the crystalline lens whether it affects the visual acuity or not 3. Anatomy Newborn - 3.5mm antero-posteriorly and 5mm equatorially Unique to the lens is continued growth throughout life Adult - 5mm antero-posteriorly and 9 - 10mm equatorially-i.e.. top to bottom With age the lens becomes larger, more compact and less elastic The lens is a biconvex optical structure behind iris and in front of vitreous in posterior chamber of the eye It is avascular and not innervated Encircled by ciliary processes from which the zonules (suspensory ligament) radiate to the lens surface Zonules hold the lens in place and mediate the accommodative movements of the ciliary muscle, therefore altering the lens shape. Outmost layer is an acellular capsule (basement membrane) that surrounds the lens Anteriorly and just under the anterior capsule is the lens epithelium Inner body of lens composed of tightly packed highly organised lens fibres Innermost layer called the nucleus Outer layers cortex 4. Red reflex with pen torch 5. Nuclear cataract ( N.B. Pseudoexfoliation) 6. Brunescent nuclear sclerosis 7. Cortical cataract and Posterior subcapsular cataract 8. Cortical Cataract 9. Cortical cataract- multiple white spokes 10. Aetiology of Cataract Age related Physical - Trauma (often unilateral) Electric shock (anterior subcapsular) Radiation Systemic - Diabetes Dermatological - Atopic dermatitis CNS disorders - Neurofibromatosis II which is one of the group of harmatomatous disorders called the PHACOMATOSES Drug induced -Amiodarone and- also a cause of corneal verticillata Iatrogenic- Corticosteroids (posterior subcapsular) 11. Corneal verticillata 12. Secondary Associated with Retinitis Pigmentosa Uveitis- intraocular inflammation Glaucoma, Corneal graft, vitreoretinal and any intraocular surgery Congenital Hereditary disorders Maternal rubella Systemic disease e.g. galactosemia Myotonic Dystrophy Chromosomal Trisomy 13 (Pataus syndrome) Trisomy 18 (Edwards syndrome) Trisomy 21 (Downs syndrome) 13. Symptoms of cataract Glare Gradual loss of vision unless traumatic Reduced near vision i.e. difficulty reading - seen in posterior subcapsular type Central lens opacities may decrease pinhole vision Second sight - nuclear cataracts cause changes in refractive index of lens so that they become more myopic and one may not need reading lasses (Normally when one ages one becomes more presbyopic, i.e. near-sighted requiring more plus lens) 14. Examination Pen torch- red reflex Ophthalmoscopy (direct)- red reflex vs. black opacities in pupil area Slit lamp examination distinguishes the cataract subtype. 15. Red reflex with pen torch and note the white cortical lens opacities 16. Treatment Surgical treatment is the only definitive treatment to remove a cataract Indications for and against surgery The aim of cataract surgery which is for the most part an elective procedure is visual rehabilitation Reasons AGAINST surgery Anaesthetic risk e.g. if unsuitable for LA but GA risk high Severe amblyopia already investigated and documented Extensive age-related macular degeneration or other retinal pathology Total afferent pupillary defect 17. Other reasons for lens extraction Clear lens extraction may be performed- i.e. no significant cataract present but lens may need to be removed Severe myopia Patients may elect to have this done at an early age rather than wait to have cataract develop therefore avoiding need for thick spectacles or contact lenses Dislocated lenses Pseudoexfoliation- can sometimes have associated glaucoma and systemic manifestations with this Trauma Systemic conditions Marfans- typically upward dislocation of lens Homocysteinuria typically downward dislocation of lens Weill-Marchesani Sulphite-oxidase deficiency 18. Dislocated lens in Trauma 19. Downward dislocation of lens can be seen in homocysteinuria 20. Types of Anaesthesia Local- most common Topical anaesthetic drops Retrobulbar, peribulbar, sub-Tenons injections of local anaesthetic General (e.g.) Children Handicapped Parkinsons disease Nystagmus 21. Types of cataract surgery Intracapsular Rarely done Removal of lens and capsule Anterior chamber intraocular lens used Extracapsular cataract extraction Removal of lens but capsule left behind 22. Phacoemulsification The most common type of extracapsular surgery today is : Phacoemulsification- ultrasonic lens fragmentation with simultaneous aspiration of lens fragments Sophisticated small incision type (approx. 2.7-3.5mm wound incision) Faster visual recover with fewer complications Suture not routinely place In Extracapsular surgery: The intraocular lens is inserted into the capsule either by injection or unfolding If posterior capsule significantly damaged during surgery or deemed to be unstable lens may be inserted in the sulcus- space between iris and anterior capsule or alternatively into the anterior chamber. The latter must occur in conjunction with a peripheral iridotomy 23. Intraocular lens 24. Other Can combine cataract surgery with: Glaucoma surgery Corneal graft surgery Other surgery 25. Post-operative care and visual rehabilitation Combined steroid and antibiotic eye drops to be tapered over 4 weeks See at 1 day, 2 weeks and 1 month post- operatively If have artificial lens (pseudophakic) will need reading glasses post-operatively as no accommodation If no lens in eye (aphakic) correct with spectacles or contact lens Thickening of posterior capsule i.e. an after cataract treated with YAG laser 26. Posterior capsular thickening with YAG laser capsulotomy 27. Laser Eye Surgery Excimer laser Therapeutic- removal or superficial cornea in recurrent erosions Refractive LASIK or Laser assisted in situ keratomileusis LASEK or Laser assisted epithelial keratomileusis PRK OR ASA or Photorefractive keratectomy or Advanced Surface Ablation Refractive Surgery may be used to correct Myopia, Hyperopia and Astigmatism 28. VIDEO OF PHACOEMULSIFICATION

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