Intacs

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Information about Intacs
Health & Medicine

Published on January 20, 2009

Author: Iogen

Source: slideshare.net

Description

Indications, nomogram and results of Intacs surgery

Intacs Surgical technique results Maria Clara Arbelaez, MD Muscat Eye Laser Center Sultanate Of Oman

Indication Reduction or elimination of myopia and astigmatism in patients with keratoconus that have problems wearing their contact lens or spectacles, so that their functional vision may be restored and the need of PKP may potentially deferred FDA approved labeling

Rings External diameter 8.0 mm  Internal diameter 6.77 mm  With of each segment 0.65mm  Angulations 23 degrees 

Inclusion Criteria Includes, but not limited to: – PKP a consideration – Diagnosis indicates ectatic condition – Contact lens intolerant; discomfort problems throughout the day or part of the day – Clear central cornea – Mean Keratometric reading between 45-60 – Pachymetry at least 350µ at thinnest point, and at least 450µ at incision point – Older than 21 years

Contraindications Cornea thinner than 449 on the incision site  Collagen vascular or immunodeficiency  diseases Pregnant or nursing  Other conditions e.g. recurrent corneal  erosion syndrome or corneal dystrophy Patients on Accutane or Cordarone 

Intacs Nomogram I: Developed by: Mark Swanson, M.D. Keratoconus & Post-Hex, RK and AK Ectasias & Post Incisional Unstable Cornea (Centered Posterior float 50% within the 3mm optical zone) Spherical Equivalent Intacs size +1.00 to -2.00 .250 mm -2.00 to -3.00 .300 mm -3.00 to -4.00 .350 mm -4.00 to -5.00 .400 mm -5.00 and higher .450 mm

Intacs Nomogram II: Developed by: Mark Swanson, M.D. Keratoconus, Pellucid Marginal Degeneration (De-centered Posterior Float 50% outside the 3mm optical zone) Sph. Equivalent Inferior Intacs Superior Intacs +1.00 to -2.00 .250mm .300mm -2.00 to -3.00 .250mm .350mm -3.00 to -4.00 .300mm .400mm -4.00 to -5.00 .300mm .450mm -5.00 and higher .350mm .450mm

Intacs Nomogram III: Developed by: Mark Swanson, M.D. Myopia & Post-Lasik Ectasia INTACS Inserts Predicted Nominal Predicted Average Thickness (mm) Correction Correction (D) __________________________________________________________ 0.210mm -0.75 D -0.500 to -0.875 D 0.230mm -1.00 D -1.000 to -1.125 D 0.250mm -1.30 D -1.250 to -1.500 D 0.275mm -1.70 D -1.625 to -1.750 D 0.300mm -2.00 D -1.875 to -2.125 D 0.325mm -2.30 D -2.250 to -2.500 D 0.350mm -2.70 D -2.625 to -2.750 D 0.375mm -3.00 D -2.875 to -3.125 D 0.400mm -3.40 D -3.250 to -3.500 D

Pre surgical plan step 1 Verify ectatic indication, and patient acceptance criteria a) Keratoconus & Post-Incisional surgery Nomogram I ___________________________________________________________ b) Keratoconus, Pellucid Marginal Degeneration Nomogram II ___________________________________________________________ c) Post-Lasik Ectasia Nomogram III

Pre surgical plan Step 2 Determine Incision Placement (steep topographic meridian) a) If the steep refractive axis is >20° from the topographic Max K, the difference is typically related to patient head compensation. Re-refract (cycloplegic) b) Verify steep refractive axis within 20° of topographic axis c) Default to topographic Max K (steep axis) d) In PMD, the steep axis will typically present across the top of the “crab claw” or “kissing dove” topographic image.

Pre surgical plan Step 3 Select Sizes based on Spherical Equivalent and appropriate Nomogram Central Cone (Symmetric Sizes) – Use Nomogram I – Effect – maximize flattening of cone De-Centered Cone (Asymmetric Sizes) – Use Nomogram II – Effect – maximize movement of posterior anomaly toward the optical center to normalize refraction Myopia & Post-Lasik Ectasia – Use Nomogram III – Centered Post-Lasik Ectasia – De-Centered Post-Lasik Ectasia – Myopia

Pre - Surgical Guidance Utilize a cycloplegic refraction when recalculating the 1. spherical equivalent for the steep axis incision placement On corneas where the pachymetry reading is >500µ in the 2. center of the 3mm zone, use the next thicker size on the Nomogram Patients with large dilated pupil diameters(>7mm) may be 3. predisposed to low light visual symptoms (such as glare and halos) post operatively and should be appropriately advised.

Surgical Guidance: Utilize ultrasound pachymetry at SITE OF INCISION 1. Make incision at 75% depth, (not less than 50% depth) 2. Constantly hydrate the cornea throughout the surgical 3. procedure Precisely execute pocketing step following incision 4. Incision placement for Pellucid Marginal Degeneration or 5. Pellucid-like cases will typically be on a line across the top of the “crab claw” or “kissing doves” shapes Stability of the vacuum centering guide (VCG) while 6. tunneling is KEY to proper depth of the segments

Suture Guidance: Indication Suture Minimum Tightness Suture time Period (D) _____________________________________________________ KC,PMD Tight 90 Post-LASIK Medium 30 Myopia Tight 10

Population 28 patients 29 Eyes (3 post LASIK  ectasia) Age 25y (from 17 to 35)  pre SR equiv: mean -5.56 D ± 3.23 D (from -14.50 to -0.63) pre SR sph: mean -3.72 D ± 3.36 D (from -12.50 to 0.75) pre SR cyl: mean -3.66 D ± 1.67 D (from -8.00 to -0.75)

Investigation pre -1m-3m 6m-1y Manifest and Cycloplegic refraction  Ultrasonic Pachymetry DGH 500  Corneal Topography (Opticon - Scout)  Corneal Tomography (Pentacam)  Wavefront ( Schwind Aberrrometer)  Complete Ophthalmic examination  Goldman tonometry 

Rings used Symmetric 25/29  – Size 450:10/29 400:4/29 350:4/29 300:5/29 250:2/29 Asymmetric 4/29  – Size 450/300 450/350 450/350 450/350

Surgical Technique Operative  – Topical anesthesia – Schwind calibrated suction pump and modificated suction tube POP  – Ocacin – Efemoline – Therapeutic CL 3 days

Attempted cyl vs Achieved Attempted Cyl vs SIA (Scatter) 10 eyes Attempted Cyl vs SIA (Scatter) 6 eyes 7 7 6 6 5 5 Maria Arbelaez, MD Maria Arbelaez, MD 4 4 3 3 2 2 1 1 0 0 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Attempted Cyl [D] Attempted Cyl [D] 3m 6m

Defocus Equivalent 3m-6m 3 m (16) 6 m (10)

Efficacy pre op (28) 1 m (22) 3 m (16)

SR Attempted vs Achieved PREDICTABILITY: Attempted vs Achieved (Scatter) 10 eyes PREDICTABILITY: Attempted vs Achieved (Scatter) 6 eyes 15,00000 15,000 13,85833 13,892 12,71667 12,783 11,57500 11,675 10,43333 10,567 9,29167 9,458 Maria Arbelaez, MD Maria Arbelaez, MD 8,15000 8,350 7,00833 7,242 5,86667 6,133 4,72500 5,025 3,58333 3,917 2,44167 2,808 1,30000 1,700 0,15833 0,592 -0,98333 -0,517 -1,625 -2,12500 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Attempted delta SR equiv. [D] Attempted delta SR equiv. [D] 3m 6m

Preop BCVA vs postop UCVA-Percent 3 m (16) preSCVA (28) 6 m (10) preSCVA (28)

Refractive Outcome % pre op (28) 3 m (16) 6 m (10)

Safety 3 (15) 6 (10)

Stability STABILITY: Achieved Change in Refr. over Time 30,00 28 21 18,75 16 Maria Arbelaez, MD 10 7,50 1 -2 -2 -2 -3 -3,75 -5 -15,00 pre op 1m 3m 6m 9m

3m 6m

Preop vs 6 m pop Pop prep Pre Pre Pre Pre SR Pre Pre rin Pop Pop pop Pop Pop sr VAS ak vasc sph cyl equiv axis vacc g sup inf vasc sph cyl axis equiv C -8.0 479 0.05 -0.50 0 -4.5 55 0.4 AS 450 300 0.1 -5.5 -3.25 92 -7.12 0.5 -3.2 -0.7 533 0.05 -4.00 5 -5.625 166 1 S 450 450 0.8 5 -2.25 157 -1.87 1 -5.2 505 0.15 -0.75 5 -3.375 76 1 S 300 300 0.4 0.75 -3.25 11 -0.87 0.8 -3.0 -1.2 482 0.20 -2.00 0 -3.5 32 0.6 S 300 300 0.3 5 -2 30 -2.25 0.6 -3.0 416 0.15 -1.00 0 -2.5 163 0.9 S 300 300 0.7 1.25 -2.25 171 -0.12 0.8 -4.5 561 0.15 -0.25 0 -2.5 175 0.8 S 350 350 0.4 -1 -1 168 -1.5 0.9 -5.7 535 0.10 -5.00 5 -7.875 39 0.4 S 450 450 0.6 2.75 -1.75 100 1.88 0.6 -3.0 485 0.10 -1.75 0 -3.25 95 0.63 S 350 350 0.6 1.5 -2 82 0.5 0.6 -2.0 464 0.05 -3.00 0 -4 90 0.8 S 400 400 0.3 -2.5 -2 167 -3.5 0.8 -2.7 522 0.30 0.75 5 -0.63 64 0.5 S 250 250 0.1 -1 -3 -3 83 0.4

Summary Preop vs 6m pop keratometry Preop Preop preop Preop Postop Postop Postop Postop K1 a1 K2 a2 K1 a1 K2 a2 47.57 139 44.78 49 47.68 143 45.47 53 46.41 68 43.26 158 43.3 55 39.91 145 47.61 117 43.1 27 46.35 108 42.35 18 47.63 113 45.17 23 46.57 117 43.44 27 43.54 63 42.11 153 44.52 90 39.89 0 45.21 87 41.54 177 40.9 29 42.6 119 53.98 114 49.1 24 50.95 115 44.99 25 47.37 62 45.84 152 46.97 77 44.32 167 47.85 170 46.81 80 49.21 75 45.18 165 48.88 139 44.69 49 49.07 150 46.5 6

PREOP 6M POSTOP Median 0.13 0.40 Stdev 0.08 0.25 vasc Min 0.05 0.05 Max 0.30 0.80 Median -1.38 -0.88 Stdev 1.79 2.34 sphere Min 0.75 1.5 Max -2 -5.5 Median -3.13 2.13 Stdev 1.82 0.67 cyl Min -2 -1 Max -8 -3.25 Median -3.44 -1.69 Stdev 1.96 2.45 Sr equiv Min -0.625 0.5 Max -7.87 -7.12 Median 0.72 0.70 vacc Stdev 0.23 0.19 Min 0.40 0.4 Max 1 1 Summary preop vs 6m postop

PREOP 6M POSTOP Median 47.59 46.77 Stdev 2.75 3 k1 Min 43.54 40.9 Max 53.98 50.95 Median 44.74 43.88 k2 Stdev 2.28 2.28 Min 41.54 39.89 Max 49.1 46.5 Preop vs 6 m keratometry

Best case Preop Pak 416 VASC 0.25 -1.25 -2.25 x 120 VACC 1.2 Symetrical ring 250 axis 30 Apex 44.74 Postop 6m VASC 1.2 +0.25 -1.50 x 119 VACC 1.2

Worst case Preop post LASIK ectasia Pak 522 VASC 0.30 +0.75 -2.75 x 64 VACC 0.5 Symetrical ring 250 axis 145 Apex 58.98 Postop 6m VASC 0.05 -1.00 -2.50 x 83 VACC 1.4

Post LASIK ectasia case Preop Pak 416 VASC 0.15 -1.00 -300 x 163 VACC 0.8 Symetrical ring 300 axis 60 Apex 46.82 Postop 6m VASC 0.7 +1.25 -2.25 x 171 VACC 0.8

Complications Intraoperative none  Postoperative  – Not enough effect – Migration 1 eye (1 week pop suture not enough tight) – Channel Deposits (2 eyes)

Conclusion High patient satisfaction  Decrease on corneal steepening  Spherical equivalent and astigmatism significantly  reduced UCVA and BCVA improved  UCVA not direct relation with manifest refraction  Predictability?  On post LASIK ectasia surgical technique more  critical Further follow up is needed 

References Levinger S.and cols Keratoconus managed with Intacs: one year  results Arch Ophthalmol 2005 Oct 123(10) 1308-14 Hellstedt T and cols Treating keratoconus with Intacs corneal ring  segments J Refract Surg 2005 May-Jun 21(3) 236-246 Alio JL and cols One or 2 Intacs segments for the correction of  keratoconus J cataract Refract Surgery 2005 May,31(5) 943-956 Malaroni A. and cols Conservative treatment of early and moderate  pellucid degenaration: a new refractive approach with intracorneal rings Ophthalmology 2005 Apr 112(4) 660-6 Pokroy and cols Single Intacs segment for post-laser in situ  keratomileusis keratectasia J Cataract Refract Surg 2004 Aug30(8) 1686-95 Boxer BS and cols Intacs for Keratoconus Ophthalmology 2003 Aug  110(8) 1475

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