REFRACTIVE LENS EXCHANGE(CLEAR LENS EXTRACTION).pptx by sudhakar.pptx

Refractive lens exchange or Clear lens extraction

1. REFRACTIVE LENS EXCHANGE (CLEAR LENS EXTRACTION)

2. HISTORY Abbe Desmonceaux (1776) - first surgeon to perform clear lens extraction Vincenz Fukala (1890)- first systematically performed RLE in high myopics Introduction of first PCIOL by Harold Ridley in 1949 was the first big step in contemporary cataract surgery Invention of foldable IOL in 1980

3. INDICATIONS Refractive errors with associated lens opacities ,specially in presbyopic age High refractive error myopia >10D and hyperopia >5D in patients >40 years age are ideal for RLE Hyperopes in presbyopic age are the best candidates

4. CONTRAINDICATIONS Retinal diseases that are potentially vision impairing – macular degeneration - peripheral degenerations - retinal breaks Occupational night drivers Patients with unrealistic expectations

5. Ideal Technical elements of a successful RLE surgery Anatomically minimally invasive surgery with minimal trauma to the ocular tissues. A secure, watertight 2.5 mm or less micro incision in clear cornea, optimally 1.0 mm from the limbus , situated at the steepest corneal meridian Fixation of an appropriate PC-IOL in the capsular bag with low induction of PCO

6. Special considerations in RLE surgery In eyes with high axial myopia, depth and stability of the anterior chamber are abnormal, which necessitates the use of dispersive viscoelastic . In eyes with excessive axial length, the risk of perforation during retrobulbar injection is high. In short, hyperopic eyes, an increased risk of choroidal effusion and macular edema should be considered.

7. ADVANTAGES - Technique familiar to all ophthalmologists - Does not need further instrumentation or training DISADVANTAGES - Intraocular procedure - retinal complications increased with removal of crystalline lens

8. PREOPERATIVE WORK-UP Proper informed consent Workup and surgery should be meticulous Detailed anterior segment and posterior segment examination should be done to rule out any preexisting pathology - raised IOP - vitreous degeneration - retinal degeneration

9. Any retinal lesions should be treated first Accurate refraction and corneal topography should be done IOL BIOMETRY - keratometry and A-scan - Single most important factor - to get emmetropic eye biometry should be error free

10. Keratometry - first step of biometry - manual or auto keratometer - 1D error in corneal power resulting in 1D postoperative refractive error

11. A- scan a) Applanation /contact A-scan - supine position is preferable - do not indent the cornea - place the probe in the center of the cornea while maintaining the probe vertical - multiple readings should be taken - most accurate readings should be averaged

12. b) Immersion A- scan - more accurate 1mm error in AL resulting in 2.35D postoperative refractive error in 23.5mm eye IOL master is more accurate than ultrasound biometry Best formula to calculate IOL power in Myopia- SRKt Hyperopia - Holladay II

13. SURGICAL PROCEDURE RLE is a refractive procedure not one of visual rehabilitation Extreme care should be taken to avoid any complications Aseptic precautions should be taken Topical or Peribulbar anaesthesia Surgical steps are same as routine phacoemulsification

14. Incision – temporal clear corneal incision is the best route of entry - size 2.5mm or less Capsulorhexis - good dispersive viscoelastic (Na chondrotin sulphate ) should be used - central and just smaller than the optic of IOL to be used - large/ decentered rhexis will cause capsular fibrosis , PCO , IOL decentration - runaway rhexis or extension of rhexis results in PCR

15. Irrigating solution used should be of best quality preferably BSS with glutathione All tubings , cannulae , knives should be single use disposable Hydrodissection - should be complete - forced rotation of nucleus in the absence of good hydrodissection results in severe zonular damage

16. Low phaco power with moderate flow and vaccum will be ideal Removal of the nucleus by creating a wide, deep, long trench with just irrigation and aspiration Cortical cleanup should be complete Posterior capsular polishing should be done if necessary

17. CHOICE OF IOL DURING RLE IOL used should give good centration with minimal PCO incidence Posterior square edge design with haptics will be the best choice If IOL were to be placed in the sulcus power should be reduced by 0.5D

18. TRADITIONAL MONOFOCAL IOLs - Very effective in providing one optimal focusing distance - require additional spectacle correction to correct vision at all other distances

19. MULTIFOCAL IOLs - provide good uncorrected distance and near vision - 2 types a) Refractive – very pupil dependent b) Diffractive- less pupil dependent - Disadvantages - loss of contrast sensitivity - glare and halos from light sources during night vision

20. PSEUDOACCOMMODATIVE IOLs - less pupil size dependent - do not provide good intermediate vision

21. ACCOMMODATIVE IOLs - move anteriorly during near vision

22. RLE IN MYOPIA Patients with high myopia are often willing to have RLE Contraindications – Eyes with advanced peripheral lattice degenerations – Young eyes with no posterior vitreous detachment – Laquer cracs in high myopia or myopic CNV in the fellow eye – Presbyopic eyes with macular degeneration beginning in the fellow eye

23. Complications 1.Retinal detachment - most vision threating Risk factors – increased axial length - age <50 years - males - caucasian race - peripheral retinal degenerations - intraoperative PCR - Nd:YAG capsulotomy

24. 2. myopic macular degeneration 3. cystoid macular edema 4. posterior capsular opacification 5. halos and glare 6. choroidal neovascularization (CNV) 7. ARMD

25. RLE IN HYPEROPIA Indications – Beginning presbyopia with weakened accommodation of crystalline lens – High order aberrations, when laser surgery need to be avoided – High hyperopia in patients with congenital systemic condition who are unable to wear spectacles or contact lenses

26. Small hyperopic eyes with shallow AC are more predisposed to closed angle glaucoma This makes even moderate hyperopia an indication for RLE with good benefit/risk ratio

27. Complications - PCO – most common - secondary postoperative IOP raise - postoperative uveal effusion

28. RLE IN CHILDREN Indications – High anisometropia or severe bilateral ametropia – Congenital conditions disabling proper binocular vision – Non-compliant children with high refractive errors where treatment with refractive laser surgery is impossible

29. RLE IN ASTIGMATISM Shimizu (1992) – invented Toric IOL Posterior chamber toric lens implantation is a new highly predictable surgical option for patients with pre existing corneal astigmatism

30. RLE IN PRESBYOPIA Accommodative or Multifocal IOLs Aim – to restore good distance, near and intermediate visual function

31. T H A N K Y O U