Small Incision Cataract Surgery (SICS) and IOL Implantation
(My learning curve, first 100 cases.)
Aim of the study: To evaluate the technique of scleral tunnel Cataract surgery and I.O.L. implantation that is Phacoless and sutureless.
Introduction: To switch over to sutureless cataract surgery, ie phacoless is quite exciting and interesting also. The reason behind this is (i) It is cost effective. Not only most of our patients can not afford phaco surgery but also most of us (surgeons) can not afford a good phacoemulsifier and its allied expenditure in developing countries. (ii) this procedure produces similar results such as faster and satisfactory visual rehabilitation. One can achieve the same goal that of phaco simply avoiding long and risky learning curve of phacoemulsification.
Materials and methods: One hundred consecutive cases of various cataract, attending to ophthalmology OPC of R.M.Medical College Hospital,Annamalai University, were taken up for this study. This includes 79 cases of senile cataract, 5 cases of child- hood cataract and 10 cases of complicated cataract. Thorough preoperative evaluation of anterior segment of the eyes was done by biomicroscopy, posterior segment by B scan ultrasonography. The cases with posterior segment problems were excluded from the study. The keratometry and I.O.L. power were calculated using Teknar Image 2000 A and B scan (biometry).The surgeries were performed under peribulbar anaesthesia except for childhood cataracts, which were undertaken with general anaesthesia. Peribular anaesthesia was achieved by giving 2 injections , mixture of 5cc of 2% xylocaine with 5cc of 0.5% bupivacaine by two points technique,1 without adding hylase. Facial N. block was avoided in all the cases. Ocular hypotony was achieved by ocular compresion with pinky ball.
Steps
Scleral Tunnel Incision: After Ab externo fornix based conjuctival flap,a frown tunnel incision is given with B.P.blade No.15. The size of incision, the distance between the ends of incision mostly varies from 6.5 to 8.5mm,However if it is nuclear, rock hard cataract incision may be bigger up to 10mm It is to be noted that the incision can be extended at any point of time. The anterior extent of the incision is always more than 2mm behind the limbus and two ends can be 4 to 6 mm behind the limbus.2 The tunnel was dissected with the help of sharp edge tunnel pocket blade angled No 4805(image1) or sharpedge lamellar miniature blade angled no.6600. The incision depth varies from 0.1 to 0.5 mm as the thickness of sclera at 2 mm posterior to limbus is roughly 0.6mm. Ideal depth was 1/3rd to thickness of sclera.
One should be very careful not to be very superficial or too deep to avoid complications like button hole or cyclodialysis respectively. Further the thin flap has always the tendencies to tear. The internal incision which is entry to anterior chamber was made with the help of sharpedge slit blade angled No.5540, 5520 or 5516 and latter extended after capsulorhexis.
Capsulotomy: Continuous curvilinear capsulorhexis which was innovated by Gimbel and Neuhann has revolutionised the modern cataract surgery.This was performed with either 26G bent needle or with the help of Masket Capsulorrhexis forceps. Sometimes it takes 6 months to master this technique. A rhexis of 6 to 7.5mm diameter is essential, how ever if it is nuclear cataract, one or two relaxing incision are made at 4 0’clock or 9 0’clock meridians,or else little larger rhexis can be performed very carefully because it has the tendencies to extend peripheraly.Relaxing incisions were made with the help of 26G bent needle or with vannasscissors.
Hydrodissection: The step is very essential before nucleus delivery. It is carried out with 2 ml syringe using curve 23G west lacrimal cannula, the fluid was injected beneth the anterior capsule in one or two places,however large volume are avoided.Golden ring reflex in case of soft cataract or fluid waves are observed to ensure complete hydrodissection.
Nucleus managemen: The nucleus was flipped up and rotated with the help of an I.O.L. dialer and subsequently prolapsed into the anterior chamber.3 Viscoelastic is placed both anteriorly and posteriorly.This step is essential to avoid endothelial damage .The nucleus was extracted by following technique. Microvectis or lens loop- This instrument is insunated underneath the nucleus and nucleus was expressed by gently applying forward and backward pressure after injecting viscoelastic into the anterior chamber. Sometimes the epinucleus or portion of the cortex will be sheared off by the anterior lip of the incision without damaging to the endothelium. The remaining portion of cortex can be easily rotated and extracted after injecting viscoelastic,whereas epinucleus which is always soft can be removed by viscoexpulsion or can be aspirated with 0.5 I/A canula.
Other Techniques:
(i)Nucleus capture (phaco sandwich):: In this technique lens loop or irrigating vectis is placed behind the nucleus and an I.O.L. dialer / sinskey hook is placed anterior to it and by using bimanual technique the nucleus is delivered through the tunnel.
(ii)Phacofracture: The hard nucleus is divided into two with the help of irrigating vectis/ lens loop/nucleus vectis (kansas) which is placed behind the lens and sinskey hook or sharp phaco chopper is used to break the nucleus which were expressed subsequently by either techniques described above.
The cortical remnants were aspirated as usually using simcoe 0.5mm I/A canula. In no case a side port entry was made during these procedures.
I.O.L. Implantation: Viscoelastic material was injected into the capsular bag and in the anterior chamber before I.O.L.implantation. The I.O.Ls used were mainly Eye Of care, Appalens,and IMD lenses with 5.5 to 6.5mm optics and 12.5mm to 13.5 mm overall diameter. In 40 eyes I.O.L.were implanted in the sulcus(image2) and in 60 eyes,implanted in the bag. Viscoelastic was aspirated and anterior chamber was formed either with balanced salt solution or air bubble injected through tunnel itself(image3)
Closing the conjuctval flap: The conjuctival flap was closed with bipolar wet field cautery following subconjuctival injection. The subconjuctival injection constitutes dexamethasone 0.5ml and gentamycin 20 mg, injected into the upper bulbar conjuctive after which eye patching applied with a pad.
Results? In 82% of cases the visual acuity corrected after one month was 6/18 or better. In 8 (8%)cases the best corrected visual acuity was less than or equal to 6/60 because, 4 cases had irreversible corneal oedema and 2 cases had decentred I.O.L. and 2 cases had dense post capsular opacification. Corneal oedema was seen in 10(10%) eyes during early post opertive period.
Complications: The most common complication was endothelial damage in 4 cases.Inferior iridodialysis in 2 cases and cyclodialysis in 3 cases.Hyphema and iritis encountered in 4 and 6 cases respectively. Out of 4 cases of PC rent vitreous loss was seen in three cases,I.O.L. decentred in 2 cases ,one had dislocation of I.O.L. which was explanted during surgery.
Discussion: The post operative visual acuity,best corrected was 6/12-6/18 or better in 82% of cases after 4 weeks. In 6 cases minimal corneal oedema subsided within 2 weeks of surgery. However in 4 cases there was irreversible corneal oedema because of endothelial trauma. This complication will be much lower as one’s learning curve is crossed. The severe corneal oedema was due to endothelial decompensation which was mostly seen in the later half of 50 cases perticularly in the camp cases,where large number of cases were operated in a single day. The results of first 50 cases were better and more encouraging may be because of extra care taken during switch over to a new procedure. In 2 cases there were inferior iridodialysis and total hyphaema which cleared slowly and visual acuity improved to 6/24 and 6/36 after 2 months of surgery. The iridodialysis in the lower part was because of iris trapped in between microvectis and nucleus during delivery of nucleus. This can be avoided by injecting adequate amount of viscoelastic into the anterior chamber andalso if little care is taken during nucleus management. In one case there was zonulodialysis IOL was dislocating into the vitreous which was explanted immediately intraoperatively. In other four cases there was PC rent and vitreous loss which was managed by vitrectomy, IOL implanted in the sulcus in three cases and in one case it was implanted in the anterior chamber. In 6 cases of complicated cataracts there was thick layer of posterior cortex, it was difficult to aspirate ,however in two cases reoperation, I/A was done easily in the second post operative period following which visual acuity improved to 6/12 and 6/18 respectively.
Although there is lack of extensive study regarding this technique(SICS),in early nineties Kansas described the phacofracture and Luther Fry the phacosandwich technique. Richard Gianetti in 1996 reaffirmed, the nucleus capture is an inexpensive, phacoless, repeatable and relatively easy method of performing tunnel incision cataract surgery. He also stressed that no side port incision is required, surgeons can obtain the benefits of small self sealing incision without the added cost of phaco.4 In all the 100 cases of this study, no side port entry was done and nucleus was delivered with the help of microvectis,small lens loop.
Conclusion: Small incision cataract surgery has contributed considerably to acclerated wound healing and minimisation of hospitalisation. The technique used here is neither phaco fracture non-phaco sandwich but nucleus is delivered by means of a microvectis with tunnel incision of size 6.5-7.5 mm for soft cataracts, and around 10 mm for rockhard cataracts. This tunnel cataract surgery is inexpensive, phacoless, relatively easy, repeatable and can be performed for any type of cataract from childhood to rockhard nuclear cataract. No side port entry is required. The wound is more secure with reduced intraoperative complications and virtually no chance for expulsive haemorrage.5 Childhood cataract is much easier as there is no nucleus and in no time chamber collapses during surgery. One can achive faster and satisfactory visual rehabilitation (image 4) without added cost of phaco and its long and risky learning curve. According to S.N. Fyodorov, Life does not stand still for a single minute, what is considered brand new today becomes outdated tomorrow. So is it not high time now to say goodbye to phaco?
References
- Nielson P.J., Allerod C.W Evaluation of local anaesthesia technique for SICS. Journal cataract Refract. Surg.1998: 1136-44.
- Kapoor Sashi Incisions. Emmetropia, Journal Intraocular Implant and Refract. Society.1999; 2:17-25.
- Mody Kirit,Singh Gagan J Small incision Non phaco cataract surgery. Emmetropia, Journal Intraocular Implant and Refract. Society.1999; 2:9-11.
- Giannetti Richard Phacoless nucleus capture through a no stich tunnel incision appears to control astigmatism. Ocular Surgery News International.1996; 7: 14-15.
- Kumar Ravindra Small incision cataract surgery without phaco-My experience. Emmetropia, Journal Intraocular Implant and Refract. Society.1999; 2:53-55.
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Professor of Ophthalmology, RMMCH, Annamalai University-608002, Tamilnadu
