Phakic Intra ocular lens

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Phakic Intra ocular lens par Mind Map: Phakic Intra ocular lens

1. Indications

1.1. Myopia >-8 D

1.2. Myopic astigmatism

1.3. Stable Keratoconus

1.4. Keratoconus with corneal cross linking

1.5. Correction of residual refractive error in post keratoplasty cases

1.6. Correction of unilateral high refractive error in anisometropic amblyopia

1.7. Correction of postop refractive surprise

1.8. Multifocal diffractive phakic IOL to correct Presbyopia

2. Advantages

2.1. Preserves corneal architecture

2.2. Preserves accomodation as lens remains is unaltered

2.3. Reversible and exchangeable

2.4. High optical quality

2.5. Minimal spherical aberrations and coma than LASIK

2.6. Predictable and stable results

2.7. Loading and implantation requires a minimal learning curve

3. Disadvantages

3.1. May cause irreversible damage such as endothelial cell loss, glaucoma, cataract

3.2. Potential risks of intraocular procedures like endophthalmitis

3.3. Not suitable in shallow anterior chambers

3.4. Non foldable variants require larger incisions, causing post op astigmatism

4. Anterior chamber depth requirements for different phakic IOLs

4.1. Measured from Endothelium AcrySof phakic: >2.7 mm Artisan-Verisyse/Artiflex-Veriflex: 2.7 mm ICL: 2.8 mm for myopia, 3.0 mm for hyperopia PRL: 2.5 mm

5. PIOL sizing is determined by Anterior chamber depth (ACD) and horizontal white‑to‑white measurementsmeasurements

6. VAULT is the Vertical distance between the back surface of ICL and front surface of the crystalline lens.

6.1. Ideal vault size 250-750 μm

7. ONE SIZE FITS ALL- 8.5mm

8. Types

8.1. Anterior Chamber

8.1.1. Angle fixated

8.1.1.1. AcrySof Cachet

8.1.1.2. Kelmann duet

8.1.2. Iris fixated

8.1.2.1. Artisan/Verisyse

8.1.2.2. Artiflex/Veriflex

8.2. Posterior chamber

8.2.1. Implantable collamer lens

8.2.1.1. Made up of biocompatible material, Co-polymer of 60% poly-hydroxy ethyl methacrylate (HEMA), water (36%), and benzophenone (3.8%) and 0.2 % porcine collagen

8.2.1.1.1. Comes with four 360 micron holes- Two on optic, one each on trailing haptic and leading haptic

8.2.1.1.2. Toric IOL comes with extra two orientation marks on optic

8.2.2. Phakic refractive lens

9. Preoperative evaluation

9.1. Visual acuity assessment -Unaided and aided, Refractive status

9.2. Slit lamp examination- Undilated and Dilated states. Anterior and posterior segment evaluation, including peripheral fundus

9.3. IOP measurement

9.4. Gonioscopy

9.5. Keratometry

9.6. Axial length

9.7. Endothelial cell count

9.8. Horizontal W-W diameter assessment using Digital callipers/orbscan/IOL Master/ AS-OCT

9.9. Anterior chamber depth- using Orbscan/Pentacam/ IOL Master/ AS-OCT

9.10. Sulcus to Sulcus diameter

9.11. Angle to Angle diameter

9.12. Pupil diameter

9.13. IOL size and power calculation

10. Patient selection criteria

10.1. Preoperative refraction (Stable refraction ( <0.5 D )for 1 year)

10.2. Age >21 years

10.3. Endothelial cell count> 2300/mm2 (>2500 cells/ mm2 if >21 years old, >2000 if >40 years old)

10.4. WTW>11 mm

10.5. Anterior chamber depth> 2.8 mm

10.6. Irido-corneal angle > 30 degrees

10.7. Pupil diameter<6.5mm

11. Contraindications

11.1. Low endothelial cell count

11.2. Low AC depth

11.3. Advance Keratoconus

11.4. Active disease in the anterior segment

11.5. Recurrent or chronic uveitis

11.6. IOP >21 mm Hg or Glaucoma/Narrow angles/Iris/Angle anamolies

11.7. Clinically significant cataract, previous corneal or intraocular surgery (to be evaluated)

11.8. Zonular laxity/dehiscence

11.9. Pre-existing macular degeneration or macular pathology

11.10. Proliferative retinopathy

11.11. Systemic diseases (eg autoimmune disorder, connective tissue disease)

12. Complications

12.1. Posterior Chamber Phakic IOL related

12.1.1. INTRAOPERATIVE

12.1.1.1. Dropping of ICL while loading

12.1.1.2. Chipping of ICL

12.1.1.2.1. Causes- Inadequate viscoelastic in cartridge, Irregular/sharp edges of forceps or Improper hold of ICL with forceps

12.1.1.3. Reverse ICL

12.1.1.3.1. Causes- Faulty loading,incorrect orientation, Inadequate OVD in anterior chamber

12.1.1.4. Damage to anterior lens capsule

12.1.2. EARLY POST OPERATIVE

12.1.2.1. Raised IOP and Glaucoma

12.1.2.2. Pigment dispersion

12.1.2.3. Uveitis

12.1.2.4. Glare and halos

12.1.2.5. TASS

12.1.2.6. Endophthalmitis

12.1.3. LATE POST OPERATIVE

12.1.3.1. Cataract due to lens touch

12.1.3.2. Endothelial cell loss and corneal decompensation

12.1.3.3. Retinal detachment in high myopia cases

12.2. Angle supported Phakic IOL

12.2.1. Pupil ovalization

12.2.2. Endothelial cell loss

12.2.3. Angle fibrosis

12.2.4. Pigment dispersion

12.2.5. Direct damage to trabecular meshwork

12.2.6. Pupillary block glaucoma

12.2.7. Uveitis

12.3. Iris fixated Phakic IOL

12.3.1. Decentration/Disenclavation

12.3.2. Endothelial cell damage

12.3.3. Uveitis

12.3.4. Iris atrophy

12.3.5. Pigment dispersion

12.4. Problems with Vaulting

12.4.1. HIGH/Excessive vaulting (>750 microns )/Large ICL

12.4.1.1. Causes Angle-closure, Pupillary block glaucoma, Pigment dispersion glaucoma

12.4.2. LOW/Insufficient vaulting (< 250 microns ) Small ICL

12.4.2.1. Cataract due to contact