FP101 : A Novel Versatile Cannula for Vitreoretinal Surgery.
Dr.Maneesh Bapaye, B12628, Dr.(Mrs) Bapaye Meenaxi Manohar, Dr.Charuta Maneesh Bapaye
Introduction:
Vitreoretinal surgery has come a long way since 1971 when Dr.Robert Machemer first described pars plana vitrectomy (PPV) with 17 Gauge vitreous infusion suction cutter (VISC). In the last decade small gauge vitrectomy systems have revolutionized outcomes of vitrectomy surgery in terms of anatomical success rates, reduction in post operative morbidity,faster post operative recovery and visual outcomes. In initial years small gauge vitrectomy had relatively limited applications due to factors like less rigidity of instrumentation, visualization systems etc. However advances in wound construction, instrumentation, fluidics, illumination, wide angle viewing systems and cutter technology have overcome initial challenges greatly thus expanding indications of small gauge vitrectomy surgery1. Valvedcannulaeare being used by increasing number of vitreoretinal surgeons as they maintain closed chamber, reduce the amount of infusion fluid used and maintain IOP better1. However it is difficult to pass soft tip instruments like soft tip cannulae and Tano’s diamond dusted membrane scraper (DDMS) through the valves.
Successful separation of posterior hyaloids face (PHF) from retinal surface is the single most important step in successful long term outcome of vitreoretinal surgery for different indications like rhegmatogenous retinal detachment, macular surgery as well as vitreoretinal procedures in diabetic patients. This step may pose a significant challenge to surgeon due to strong adhesion between PHF and retina. Various techniques to achieve posterior vitreous detachment (PVD) intraoperatively have been described. Use of active aspiration using vitreous cutter or soft tip cannula as well as non-aspiration techniques like use of DDMS to create dissection plane have been described. Very frequently combination of aspiration and non-aspiration techniques might be necessary to achieve successful PVD induction. This needs frequent change of instruments which prolongs surgical time and propensity for complications.
We describe a novel instrument which combines aspiration as well as non-aspiration techniques for PVD induction, Bapaye’s aspiration scraper (Epsilon, Chino,CA, USA).It is also useful in various vitreoretinal interface procedures due to its special design.
Description of instrument:
The instrument, aspiration scraper, consists of a curved cannula attached to an ergonomic handle. The cannula is made of stainless steel. It is 32 mm long and has a gentle curve. It has outer diameter of 25 gauge. It can easily enter through valvedcannulae as it is a rigid instrument. Tip of cannula is diamond dusted to achieve scraping of vitreous/membranes and is rounded so as to make it atraumatic to retina. The cannula has a 0.25 mmaspiration port justbehind the tip. When introduced into the eye, the cannula can reach the retinal surface even in highly myopic eyes.
The handle has serrations for firm grip. It can be attached to aspiration tubing of vitrectomy machine as well as to tip of a syringe. It can be used for suction as well as for injection of vital dyes.
Clinical applications:
Though initial purpose of the aspiration scraper was to induce PVD in difficult cases, it can be effectively used in other clinical situations also. We have used this instrument in various surgical scenarios with a successful outcome.
Rhegmatogenous retinal detachment (RRD):
In RRD it is used forinduction of PVD at the posterior pole as well as peripheral retina. Dense vitreoretinal adhesions in anterior periphery can be loosened by alternative scraping and suction of the instrument. In phakic patients with RRD, it can be used to drain subretinal fluid (SRF) from peripheral break close to oraserrata with relatively less risk of lens touch due to curvature of instrument. It can also be used to aspirate air bubbles trapped in anterior hyaloid face (AHF) without traumatizing posterior lens capsule. We have used gentle suction to loosen AHF from posterior lens capsule before trimming it with vitreous cutter in a few cases.
In RRD cases where non-valvedcannulae are used, blunt rounded tip ofaspiration scraper can be used to repositretina if it gets incarcerated in cannulae, after turning off infusion. It can be used to engage and create dissection plane for PVR membranes. Significant number of mature PVR membranes can be dissected using aspiration scraper alone.
Macular surgery:
Aspiration scraper is effective in various cases of macular pathology. Besides induction of PVD it can be used for injection of vital dyes without creating a jet. The instrument can be used to scrape & create an edge of epiretinal membrane and then use aspiration to peel it off retinal surface without risk of retinal trauma. We could use it in many cases to create flap of ILM as well. However complete ILM peeling could be achieved more effectively using ILM peeling forceps.
Vitrectomy for complications of proliferative diabetic retinopathy:
In diabetic patients undergoing vitrectomy for proliferative diabetic retinopathy, aspiration scraper was very useful in clearing blood clots off retinal surface. It can also be used to identify edge of flimsy fibrovascular membranes densely adherent to retinal surface. In cases of combined RD, active suction is used for fluid-fluid exchange to remove thick SRF.
Discussion:
Diamond dusted membrane scratcher (DDMS) was described by Yasuo Tano in late 1990s.2 It consists of 3 parts namely diamond dusted flexible silicon tip which is connected to a metallic rod which inturn is attached to a plastic handle. The flexible and diamond dusted tip of DDMS is gently moved across retinal surface to try and identify the free edge of epiretinal membrane which can be then removed by end gripping forceps or with DDMS itself. DDMS is used to initiate PVD induction where it is used to create a break in vitreous in posterior precortical vitreous pocket (PPVP) after staining with triamcinolone and then extended peripherally. Ingress of irrigation fluid helps in progressive separation of PHF and retina. When introduced, it was a 20G instrument but with advent of small gauge vitrectomy systems it is available in 23 & 25 gauge also. However due to the flexible tip, it is difficult to insert it through valvedcannulae of vitrectomy systems. Now retractable DDMS is available for such cases. However reports of breakage of flexible tip with retention with in valvedcannulae or its loss onto the retinal surface have been described by Felcida V et al3. Gupta and Goldsmith4have reported a case of retained diamond particle on to retinal surface after use of DDMS.
Induction of PVD remains a challenge in eyes with dense vitreoretinal adhesions like in pediatric& highly myopic eyes.Various methods for PVD induction have been described. They include active suction with cutter at the edge of optic nerve head (ONH) or at PPVP. Once an edge is created, active suction can be used to pull on vitreous till peripheral retina. ‘Hydrodissection’ of vitreous has been described as a safer method to reduce possibilities of complications. DDMS has been used as described above.Bimanual technique with simultaneous use of illuminated pick and active suction with cutter has been described as well. Liquid perflurocarbon has also been used for progressive separation where active suction is used to separate vitreous and small amounts of LPFC is used to further to complete the procedure. Pharmacotherapeutic methods like Ocriplasmin are commercially available while anti-integrin agents are under trial. PVD induction is associated with complications like retinal break formation in peripheral retina and intraoperative hemorrhage. In high myopic eyes as well as in diabetic patients failure to notice vitreoschisis may lead to PHF remaining attached to retina and leading to contraction and causing PVR changes at latter date.
For inducing PVD at posterior pole, as with other techniques, PHF is stained with triamcinolone. Aspiration scraper is used to gently scrape and simultaneously aspirate and engage vitreous in PPVP. As the PHF separates from retina, PVD can be extended along the vascular arcades. If any area of dense vitreoretinal adhesion is noted, vitreous can be scraped off retinal surface before proceeding with active suction. Once sufficient amount of PVD is achieved, vitreous cutter can be used to trim the vitreous and complete PVD with active suction.
In cases of RRD, adhesions between retina and vitreous are often very dense in retinal periphery especially in high myopic patients. Attempted separation of vitreous with vitreous cutter is prone to develop iatrogenic retinal breaks while incomplete separation can lead to anterior proliferative vitreoretinopathy changes post operatively. We found that the use of aspiration scraper helped in this step. Alternate use of scraping and gentle active suction helps to loosen the vitreoretinal adhesions in periphery which can later be trimmed by vitreous cutter. Curvature of the instrument makes it safe to use in peripheral retina even in phakic eyes as it can reach extreme periphery without causing lens touch.
In patients with RRD, presence of peripheral retinal holes close to oraserrata necessitates making drainage posterior retinotomy to drain subretinal fluid more completely especially in phakic eyes as straight instruments like flute needle may not reach peripheral retinal break without causing lens touch. Curvature of aspiration scraper along with placement of aspiration port along outer curve allows access to peripheral retinal holes in all quadrants including superior ones. Gentle active suction can be used to drain SRF gradually using fluid-fluid exchange as well as air-fluid exchange techniques to achieve more complete flattening of retina. It obviates need of posterior drainage retinotomy in significant number of cases.
In RRD cases where non valvedcannulae are used, highly mobile retina can get incarcerated into the sclerotomy. With help of blunt rounded tip aspiration scraper can be used to reposit it after turning off infusion. When cutter is used for this purpose, chances of creating iatrogenic breaks are higher if suction or cutting is activated. It can also be used to engage and create dissection plane for PVR membranes. Significant number of mature and thick membranes can be dissected using aspiration scraper alone.
The aspiration scraper combines aspiration and non aspiration techniques for surgical induction of PVD and also aids in removal of thick epimacular membranes with macular pucker. It is also used to create an edge in epimacular membranes and active suction can be used to it peel of retinal surface in non touch manner. It reduces risk of focal retinal haemorrhages, focal retinal edema and eccentric retinal hole formation which may be associated with these procedures.
It can be used for injection of vital dyes without creating a jet. The tip of cannula can be placed close to optic disc and brilliant blue dye is injected. It flows over macular area through posteriorly placed hole.
As mentioned before aspiration scraper can be used to create a flap for ILM peeling. However we found use of ILM peeling forceps more effective and less traumatic to the retina for completion of ILM removal. Kuhn at al5 have suggested that use of DDMS for enlargement of ILM free area is associated with higher possibility of trauma to nerve fibre layer and functional damage. Same would be true with aspiration scraper and we would not encourage enlargement of ILM peeling with scraping alone.
During vitrectomy for PDR, intraoperative haemorrhage from fibrovascular proliferations is commonly seen. This haemorrhage can be controlled by raising intraocular pressure, performing fluid-air exchange or use of diathermy. Once active haemorrhage has ceased, blood clots formed on retinal surface hinder surgical view. Removal of these blood clots can be difficult due to dense adhesion of organized clot to retina. Risk of trauma to underlying retina is very high during attempted removal of the clots. We found use of non aspiration and aspiration methods with aspiration scraper to be safe and effective in removal of these clots. In case of active bleeders, using bimanual surgery technique, intraocular cautery and aspiration scraper can be simultaneously used to identify bleeders and cauterize them. We have used it to identify edges of densely adherent flat fibrovascular proliferations as well as to drain thick SRF in cases with combined rhegmatogenous and tractional retinal detachments. In cases of SRF drainage, aspiration port is held close to retinal hole. As this port is not at the tip, it usually does not aspirate the retinal tissue making this procedure safer.
Multifunction instruments like aspiration cautery, illuminated picks, illuminated laser probes have been used effectively prior to wide spread acceptance of small gauge. However in the era of small gauge vitrectomy, such instruments are not very common. With aspiration scraper, we have attempted to combine aspiration and non aspiration for vitreoretinal interface manipulations. Since the instrument has 25 gauge diameter it is compatible with modern small gauge vitrectomy systems.
However we would like to caution surgeons that unlike DDMS, this is a rigid instrument. While using non aspiration function it has to be brushed carefully and gingerly over retinal surface. It can traumatize the retina if dragged roughly over it. Iatrogenic breaks can also occur if excessive force is used.
Conclusion:
Bapaye’s aspiration scraper is a new and effective device which can make vitreoretinal surgery safer and faster by making various vitreoretinal interface manipulations, hitherto prone for complications, easier. It can be potential game changer in small gauge vitrectomy surgery.
References:
- Mohamed S, Clease C & Tsang CW. Review of small gauge vitrectomy: Progress and Innovation. Hindawi Journal of Ophthalmology, Volume 2017, Article ID 6285869: Pg 1-9.
- Lewis JM, Park I, Ohji M, Saito Y, Tano Y. Diamond-dusted silicone cannula for epiretinal membrane separation during vitreous surgery. Am J Ophthalmol 1997; 4: 552–554.
- Felcida V, Kumar N, Haynes R, Habal S & Tyagi AK. Retained tip of diamond dusted membrane scraper during vitrectomy in a valved cannula system. Eye (2015) 29, 574–576.
- Gupta D & Goldsmith C. Iatrogenic retinal diamond deposits: an unusual complication of using the diamond-dusted membrane scraper. Eye (2009) 23, 1750–1751.
- Kuhn F, Mester V & Berta A. The Tano Diamond Dusted Membrane Scraper: Indications and contraindications. Acta Ophthalmol. Scand. 1998: 76: 754–759.
Acknowledgement:
Authors would like to acknowledge contribution of Mr. Mateen Amin of Epsilon in making prototypes of instrument.
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