MIVS

Micro incision vitrectomy surgery

1. MIVS (Instrumentation, Technique, Outcome) Dr. Anuraag Singh 08-09-2018

2. Vitrectomy Surgery to remove some or all of the vitreous humor from the eye Anterior vitrectomy Pars plana vitrectomy Kasner (1962) - Open Sky Approach Robert Machmer - a 17-gauge VISC (1971), through small opening in pars plana - “father of modern vitreous surgery” Connor O’Malley(1975) – Split function system (conventional) 20-gauge “bimanual” vitrectomy using 3 ports

3. Chen (1996)- self-sealing sutureless sclerotomy for the 20-gauge Eugene de Juan (1990)- invent ed the 25-gauge with transconjunctival sutureless vitrectomy (TSV) Eckardt - a 23-gauge system & Oshima et al – a 27-gauge system

4. MIVS ( Microincisional Vitrectomy Surgery ) Defined as 23 or 25 gauge surgery using smaller probes & using a transconjunctival scleral incision The 20 G - considered the “gold standard” since 1974 First complete 23 G - introduced (2005) & judged to be safe & efficient The 23 G - combines the benefits of the 25 G & 20 G 23 G - potential to become the future “gold standard”

5. 20 G 23 G 25 G 1) Size 0.9 mm 0.7 mm 0.5 mm 2)Need for suture Yes No literature data No 3) Angled instruments Yes No literature data No 4) Instr. Stiffness (grams per 4 mm) 130 g 35 g 14 g 5) Intraocular maneuvers Easy Easy Not Easy 6) Flow rate High High Low 7) Oil injection Easy, all oil viscosities Slow, all oil viscosities Very slow, only 1,000 cS 8) Vitrectomy time Fast Fast Slow 9) Post-op inflammation Yes Poor Poor 10) Post-op astigmatism Yes No No 11) Risk of post-op hypotony No No literature data Low 12) Risk of endophthalmitis Very Low No literature data No literature data

6. 13) Use of fragmetome Yes No No 14) Change of cannula position Cumbersome Easy Easy 15) Vitreous incarceration No Possible Possible 16) Endo-illumination Good Good Good with chandelier 17) Oil removal Fast Slow Very Slow 18) Use of endolaser Yes Yes Yes 19) Vitrector cutting rate Up to 2,500 cpm Up to 2,500 cpm Up to 1,500 cpm 20)Current Indications still better for the treatment treatment of MH treatment of all of eyes with (ovelapping with 25 G), macular pathologies e.g poor visual prognosis, complicated retinal MH,ERM, vitreous opacity, such as detachment requiring mild vitreous hemorrhage, advanced PVR standard or heavy silicone proliferative diabetic and severe trauma oil endotamponade, retinopathy for complications and cataract surgery of severe diabetic complications retinopathy And in Topical anaesthesia

7. INSTRUMENTATION & FLUIDICS IN MIVS Size OF Cutter – Rigidity of 23 G vitrectome is below that of a 20-gauge,but is double that of a 25-gauge . The 23 G entry port – closer to the ti p of Instrument than 20- or 25 G

8. Microcannula System - Entry Site Alignment system (ESA) is the key to 25-gauge instrumentation The ESA system components include: the 25-gauge trocar-mounted microcannulas, cannula plugs, and infusion line Microcannula consist of two components – Polyimide cannula & polymer cannula hub with distal end cut by 30 degree angle

9. 23 G Trocar – solid stiletto with a trapezoidal cutting section & a cutting diameter of 0.74 mm compared with 0.61 mm for the 25 G Length of the stiletto is 9.6 mm compared with 9 mm for the 25 G . The trocar is in titanium & not in polyamide as is the case for the 25 G Subdivided - part out of the sclera, block length 1.5 mm,& a bulbar part of 4 mm compared with 3.51 mm in the 25-gauge,facilitates a safer oblique insertion .

10. Some System contain Integrated Scleral Marker T/C Delta – Diff between Outer Dia of Trochar & Inner Dia of Cannula. One metric that impacts cannula insertion into Trocar wound, as well as Cannula performance A large T/C delta – risk of tissue caught between Trochar & Cannula To o Smal l T / C de l t a – R em o v al o f T r ocha r c ou l d b e d i f ficu l t & inadvertent cannula removal

11. Infusion cannula has an internal diameter of 0.56 mm in 23 G & 0.42 mm in the 25 G Infusion line has a female Luer-lock connector for precise sliding fit within the microcannula

12. Flow Rate - Diameter – critical changes at Infusion line & Aspiration tip So infusion pressure o f 30-40 mmHg in 20 G to 40-50 mmHg in 25 G ( 50-60 during Dynamic state & 35-45 during Static state) Also Aspiration Vaccum raises as 150 in 20 G to 250 & 500 mmHg in 23 & 25 G Port Based flow limiting advantagenous in High cutter rates & 25 G by increasing fluidic Stability & reducing cutter induced motion of detached Retina

13. - Differences between 20,23,25 G Vitrectome Duty Cycle - % of time port open in entire cycle of cutter

14. Illumination System – Consist of Five basic building blocks Efficiency of the illumination system - depends on its coupling efficiency (measure of the power emitted from the optical source coupled into the fiber) HID lamps - metal halide and highpressure sodium Xenon lamps currently in Accurus System from Alcon

15. Reducing the diameter of a light pipe by 20% theoretically reduces the amount of illumination by ∼ 35% Wide-angle diffuse illumination preferred - visualizing transparent ILM, clear vitreous, and “glassy” epiretinal membranes Colorless tissue best seen with white light Brighter light, xenon & mercury vapor improve visualization with small fibers Two Categories of Fibres used 1) Glass fibre , 2) Plastic ( PMMA )

16. Chandelier-style illuminator – To permit 4-port Vitrectomy for Bimanual Surgery - Its handsfree & self-retaining design 25 G Chandelinear style endoilluminator compatible with Xenon 1) tip for trans-scleral insertion 2) for insertion through transscleral microcannula

17. In addition to the chandelier systems, another exciting new advance is a combined fiber optic light/laser probe made by Synergetics in 25G surgery Allow to use the laser and light simultaneously 1) Endoilluminator Wide Field monofiber for Scissors/Forceps

18. 25-gauge instruments – Tano asymmetric micro forceps for ERM or ILM peeling Eckardt micro forceps for epiretinal ERM or ILM peeling Vertical scissors for membrane dissection Silicone-tipped backflash brush needle Diamond-dusted membrane scraper for removal of PVD Rice ILM elevator for ILM peeling or posterior vitreous hyaloid separation Extendable endo-laser probe

19. 23-gauge instruments – 23G trocar kit

20. 23G vitrectomy probes –

21. Visualization – Wide-angle ( Panoramic ) viewing System -For removing peripheral VR T in rhegmatogenous RD, PVR, and giant break cases -Decreases lateral and axial (depth) resolution so should not be used for macular surgery or most diabetic traction RD Most surgeon prefer (Lander’s) Contact lens for Macular Surgery Contact based wide-angle systems , have a greater field of view than non-contact systems, eliminate corneal asphericity Wide-angle View reduces need for turning eyeball so benefit flexible tool of 25G

22. Cut Rate – - High CPM safer than Low CPM in Vitrectomy - Low CPM traction on Vitreous & Retina - High CPM enable to work close to retina with iatrogenic breaks - ‘Shaving Mode’ can be used with Low Suction & High CPM

23. Port Location – Port Closer to Tip of shaft permits to cut membranes very close to retinal surface Reducing dependence on scissors during Vitrectomy for PVR 20 G 23 G 25 G Port Distance to end 0.457 mm 0.229 mm 0.356 mm Port Area (mm2) 0.254 0.183 0.083

24. Cannula with Valves – Prevent leakage of fluid when instrument removed Maintain IOP & avoid Hypotony related complication Require precaution in injecting Silicon Oil Valve cannula (DORC). A cap-like silicone membrane is mounted on the head of the microcannula. A slot in the membrane allows the insertion of instruments

25. Sclerotomies – 4.0 mm posterior to the limbus Positions : Inferotemporal - Just below 3 or 9 O’clock meridian away from lower eyelid as possible, For infusion microcannula Superonasal - on virtual line from the lowest point of the bridge of the nose extending through the center of the pupil Superotemporal - virtual line extending from the lowest point of the supraorbital rim through the center if the pupil Methods : Transconjunctival Oblique-parallel Scleral tunnel incision is favoured

26. The scleral tunnels can either run parallel to the corneoscleral limbus (a), or in an anterior–posterior direction (b)

27. Cannula Removal – Before removal, always clear the cannulas from inside Clamp the infusion cannula before removing instruments Press and Massage the sclera with a cotton tip to close wound Raise infusion pressure to 25–30 mmHG to check sclerotomy airtight If Pressure drop,perform an air or BSS refilling with 30G needle Leakage persists,suture the sclerotomy Check IOP in early postoperative period (about 6 h p.o)

28. Advantage of MIVS – Reduced the risk of reti n al breaks related to sclerotomy Re la tive lack of conjunctival Scarring 20 G PPV total sclerotomy 3mm Vs 1.5mm in 25 G PPV Low patient Discomfort Better & sooner Vision recovery time d/t less induced astigmatism & tear film disturbance Less vitreous removal in 25 G may protection for cataract rate after vitrectomy ( diabetic vitrectomy < Epimacular memb vitrectomy ) Benefits in “Shaving” off retinal surface & cutting of “Pegs” Combo Surgery in Presbyopic patients

29. Indication of MIVS – Posterior hy a loid Peeling in PDR can be Done by 3 approach with by bimanual maneuver as 1)Segmentation 2)Delamination 3)en-Block dissection Macular diseases - — Epiretinal membrane proliferation Idiopathic or secondary macular hole Macular traction syndrome Macular edema associated with diabetic retinopathy retinal vein occlusion uveitis Persistent pseudophakic cystoid macular edema Submacular haemorrhage 2) Simple vitreous haemorrhage, Persistent Vitreous Floators 3) Vitreous biopsy 4) Primary rhegmatogenous retinal detachment 5) Proliferative diabetic retinopathy with or without tractional retinal detachment, Nonclearing VH & eye with refractory CSDME (NPDR) 6) Dislocated crystalline lens fragment

30. Adult Pediatric ( For primary post pole disease) ERM Peel Zone 1 ROP with low lying RD Macular Hole Vitreous hemorrhage Posteriorly Subluxed Lens Cataract extraction Tractional RD Endophthalmitis Silicone Oil Injection ERM Peel Vitreous Hemorrhage Traumatic Paediatric Macular hole Rhegatogenous RD Persistent fetal vasculature ( wherein PP is well formed) Uveal/ Vitreous Biopsy Retained lens fragments IOFB Removal FEVR Endophthalmitis Paediatric macular pucker ( Combined Hamartoma)

31. Advantages of small-gauge vitrectomy over scleral buckle Less trauma to the conjunctiva and sclera, no need for conjunctival peritomy No manipulation of extraocular muscles,therefore less risk of postoperative strabismus None of the risks of draining subretinal fluid through the sclera No effects on refraction Better control of intraoperative tone Elimination of vitreous traction and opacity,with less risk of macular pucker Disadvantages of small gauge vitrectomy compared to scleral buckle: Greater risk of cataract Greater risk of PVR (though not yet demonstrated) More costly materials

32. Complicated Rhegmatogenous Retinal Detachment 23-gauge vitrectomy is better than 25-gauge for complicated RD Advantages of 23-gauge over 20-gauge vitrectomy for complicated RD: Less trauma to the conjunctiva and sclera Better stabilization of the detached retina because of the smaller vitrectome mouth The possibility of shifting the position of the instruments and the infusion cannula, for an easier approach to the superior sectors Disadvantages of 23-gauge compared to 20-gauge vitrectomy for complicated RD: Vitrectomy times are longer Difficult to inject high-viscosity silicone oil, if needed, because of the size of the cannula Impossible to use an angled instrument More costly materials

33. Limitation Of MIVS – Hard dislocated cataractous lens would need a 20 G F rag e matome Severe Diabetic Retinopathies & extensive traction or combined RD Silicon oil injection ,but with use of machine injectors, even 5000 centistokes oil can be injected through fine port Even with MIVS ,sclerotomies suture in case of silicon oil inj

34. Problem With MIVS – Unsutured infusion cannula – Risk of Cannula Slipping especially in eye with deep orbital socket Complication caused will depend on Infusate as – With Fluid – Serous Choroidal Detachment With Air – Subretinal air, Suprachoroidal air, Suprachoroidal Haemorrhage Accidental Withdrawal of Cannula – Conjunctiva balloons out d/t fluid seepage from patent Sclerotomy , requiring Conjunctival incision to locate Sclerotomy site & suturing

35. Problem with Protruding Cannulas – Cause problem in placing Sclerotomies in Non- standard locations e.g closer to vertical meridian in cases as eye with severe trauma, extensive scleral wounds, Presence of glaucoma drainage valves or filtering blebs Suturing Of Sclerotomy – Potential reasons for persistent leakage of Sclerotomy may require suturings ar e A) Thin Sclera as in High Myopia Sclerotomy manipulated vigorously Aggressive Vitreous base excision Open Conjunctiva as in Combined Vitrectomy & Buckling

36. Complications of small gauge vitrectomy – Intraoperative Postoperative Hypotony Hypotony Intraocular Dislocation of Cannula Endophthalmitis In s trument Breakage Retinal Detachment

37. Recent advances 25 G+ SYSTEM – MORE RIGID INSTRUMENTS PNEUMATIC DUAL-DRIVE CUTTER WITH ULTRA HIGH CUT RATE OF 7500 CPM THE PORT IS 50% CLOSER TO THE TIP AND INNER LUMEN IS ENLARGED WIDE FIELD VIEWING SYSTEM WITH 23G AND 25G ( AS ITS DIFFICULT TO ROTATE THE GLOBE )

38. REFRENCES Romano MR 1 ,  Scotti F ,  Vinciguerra P . 7-Gauge Vitrectomy for Primary Rhegmatogenous Retinal Detachment: Is it Feasible? Ann Acad Med Singapore.  2015 May;44(5):185-7. HARIPRASAD SM. Microincisional Vitrectomy Surgery for the Repair of Retinal Detachment. RETINAL PHYSICIAN 2009;NOV:103654 Rizzo S 1 ,  Genovesi-Ebert F ,  Belting C . Comparative study between a standard 25-gauge vitrectomy system and a new ultrahigh-speed 25-gauge system with duty cycle control in the treatment of various vitreoretinal diseases. Retina.  2011 Nov;31(10):2007-13.

39. THAN K Y OU !