Small Incision Cataract Surgery (SICS)

Techniques

Delhi Journal of Ophthalmology

Minimal Duration Cataract Surgery (MDCS) Small Incision Cataract Surgery (SICS) without superior rectus stitch, no conjunctival flap and no cauterization Ram Lal Sharma MS, Praveen Panwar MS

Abstract

The basis of manual small incision cataract surgery is the self sealing tunnel, which is able to deliver the nucleus comfortably. The manual small incision cataract surgery is possible without application of superior rectus suture (truly stitch less) and construction of conjunctival flap. Elimination of these two steps will not only reduce the duration of surgery (MDCS - minimal duration cataract surgery) but have other advantages like better and early healing and lesser scarring. These modifications to the conventional technique will further refine the SICS and altering the position of incision to astigmatic neutral position makes this technique at par with phaco surgery. Minimal post-operative congestion, minimal scarring and astigmatism are the final outcome of surgery. The aim of this article is to present a description and analysis of the techniques and parameters involved in wound construction in MDCS Del J Ophthalmol 2012;22(4):275-278. Key Words : Minimal duration cataract surgery, small incision cataract surgery, SICS.

Cataract surgery techniques are continuously evolving over times; more so in last 2-3 decades. While intracapsular cataract extraction (ICCE) was the most commonly performed technique in the world till seventies; in later decades extracapsular cataract extraction (ECCE) with intraocular lens (IOL) became the most common procedure. These procedures have also been replaced by small incision cataract surgery (SICS) in last decade although phacoemulsification remains a popular technique with the limitation of cost and training. The complications are devastating with phaco surgery particularly during learning, and some of the surgeon can’t perfect this technique leading to loss of precious eyes. In comparison the SICS is simple to learn, easy to master, flexible to modify and have high safety margin. Manual small incision cataract surgery (MSCIS) was developed mainly as a cost-effective alternative to phacoemulsification cataract surgery and will be the standard procedure where phaco surgery is not possible. The Western world graduated from ECCE to phacoemulsification. In the developing countries where the cost is a major issue and number of surgeries performed by a surgeon is large, duration of surgery is not only important for handling more patients but there is lesser tissue handling, coaxial light exposure and Department of Ophthalmology, IGMC Shimla, (H.P). India Correspondence to : Dr.RL Sharma E-mail : [email protected]

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less disturbances to ocular physiology. MSICS was developed after the advent of phacoemulsification, and hence it is a relatively younger technique than the latter. It is a safe, simple, consistent, stable, and cost-effective way of cataract removal. Wound construction plays a major role in MSICS, which may be more important than its role in phacoemulsification, where the size and shape and type of the wound remain same in most of the cases. In MSICS, one has the flexibility of incision size, shape and can be modified depending upon the type of technique, hardness of the nucleus, amount of astigmatism, and the condition of the endothelium. The technique of Small Incision Cataract Surgery which is performed worldwide, consist of a superior rectus suture application with formation of conjunctival flap followed by cauterisation of conjunctival and episcleral vessels along with other surgical steps. We advocate some modification of this procedure where superior rectus stitch is not applied and conjunctival flap is not made, so no cautery is used.

Techniques Modifications in the existing methods Without bridle suture Superior rectus bridle suture is required for better exposure. If the exposure is good without it why to subject the patient for additional risk of ptosis, haemorrhage, haematoma, conjunctival tears, and even perforation. Since this is a blind step, beginners particularly always find it

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difficult and invariably create complications. So Minimal duration cataract surgery (MDCS) is truly a stitch less surgery as no needle or thread is used.

Without conjunctival flap Conjunctival flap is made to expose the limbus and sclera and later to cover the incision site. While the incision width is in micron so there is no need to create a large flap cutting many vessels and requiring cauterisation. There is no need of flap construction as without stitches one does not need to cover the wound as was practice in ECCE. Rather retraction of conjunctival flap will not only cause irritation but will also delay healing and cause more scarring.

Without cauterisation Cauterisation is performed to create blood free field for tunnel construction at the cost of vascular supply; which is so vital for healing. Not only this, cautery destroys nerve supply and coagulate tissue and causes thinning of sclera which leads to delayed healing, scarring, astigmatism and staphyloma. One can have blood free field just by some irrigation during tunnel formation, once tunnel is formed the leaking vessels either stop bleeding or blood does not interfere in further manipulation as it does not enter into the anterior chamber.

Minimal Instruments There are minimal number of instruments required for MDCS as the number of steps are less. During a standard procedure only 5 instruments are required i.e. wire speculum, two forceps (Hoskin’s, Mc-pherson’s), sinsky’s hook, cannula 2-way and 23 G. The instruments like scissors, artery forceps, cautery, superior rectus forceps, needle, and threads are not required.

Procedure details

Position of surgeon and eye exposure The position of surgeon remains standard which is on head side but can be towards right side for right eye. The eye is exposed with simple wire speculum or a guarded speculum particularly in cases of narrower palpebral fissure or lid spasm; where one needs to hold the eyelids. If 1-2 mm of sclera is visible above the 12 o’clock limbus the surgery can be performed comfortably.

Incision and tunnel As superior rectus suture is not applied so globe is stabilized by holding it near the limbus at 2 o’clock position with Hoskin’s forceps or a rounded holder. The external configuration of the incision is usually straight but can be curved and it is oblique supero-temporally in right eye and supero-nasal in left eye taking 10:30 clock hour of limbus

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as centre point (Figure 1). The anterior limit of the incision is 1 mm behind the limbus, and the length of the incision (which is the distance between the two ends, but not along the curvature) varies from 5 to 6 mm for cortical cataract, and can be extended safely from 7 to 7.5 mm for brown and hard grade IV cataract. Optimal tunnel depth is usually half of the thickness of the sclera or about 0.3 mm. Incision is applied directly through conjunctiva and episcleral tissue without flap and cautery. Incision is usually sharp and there is minimal disturbance to conjunctival and episcleral vessels. Bleeding is usually minimal and can be cleared by continuous irrigation of fluid by assistant and it rarely interferes with tunnel dissection. The pocket of tunnel is dissected with crescent knife through the scleral fibres and corneal stroma and it is extended anteriorly 1.5–2 mm in cornea (Figure 2). The limbal tissue resists dissection, so care must be taken not to apply extra force forward, as this might cause uncontrolled forward corneal dissection after overcoming the sudden resistance during the dissection of the limbus and thus result in a premature entry into the anterior chamber or out of the cornea. As the dissection approaches the lateral end of the tunnel, the knife is tilted sideways while dissection is continued, creating a funnel-shaped tunnel of about 45 degrees. Thus, the internal aspect of the tunnel would be about 25% larger than the external incision. The crescent blade should be cutting while being brought out of the tissue. The pocket tunnel dissection is carried forward 1 mm into the clear cornea in front of the vascular arcade.

Site of incision in two eyes

R

L

Upper Temporal

Upper Nasal

After the construction of the tunnel, the microkeratome is introduced into the tunnel and moved forward, until the tip of the keratome reaches the end zone of the tunnel Site of incision

Superior-oblique 9-12 clock position

Tunnel position

Size of tunnel 5.5 x 2.5 mm

Astigmatically neutral site

Between 2 standard meridians

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1

5

2

3

4

6

7

8

Figure 1: Supero-oblique Conjunctivo-scleral Incision mark with blade; Figure 2: Supero-oblique tunnel construction with crescent knife; Figure 3: AC entry with keratome tunnel width 2.5mm; Figure 4: Capsulorrhexis; Figure 5: Tunnel extension before hydroprocedures so that nucleus can be delivered along; Figure 6: Hydroprocedures – hydrodissection, delineation and elevation of nucleus Figure 7: Viscodelivery of nucleus; Figure 8: IOL implantation. (Figure 3). Then, the keratome tip is tilted downwards to enable perforation into the anterior chamber. After entering the anterior chamber, the keratome is moved laterally and forward causing the internal incision to direct itself in a curved fashion parallel to the limbus. By moving posteriorly, the internal opening will move towards the limbus, and valve action will be lost leading to leakage.

Capsular opening This can be capsulotomy or capsulorrhexis, but rhexis should be either larger in size or can be enlarged by giving small cuts (2-3) on the margin with capsulotomy needle (Figure 4). Tunnel is extended before hydroprocedures so that nucleus can be delivered easily (Figure 5).

Hydro-procedures The techniques of hydro-dissection and delineation remains the same, but these two procedures can be combined with hydro-delivery of the nucleus (Figure 6).

Nucleus delivery The nucleus can be delivered in any of the three ways. It can be done either by hydro or visco or vectis delivery (Figure 7). In small and soft nucleus and fully opened eye lids, the nucleus is hydro-delineated and lifted up simultaneously out of the capsular bag and engaged in the tunnel, which is opened with the back of hydro-

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cannula, and fluid is pushed towards 6 o’ clock position and nucleus comes out easily. It can be done in a single step where hydro-dissection, delineation and delivery (D3) are done simultaneously and it causes least damage to the endothelium. The hydro-delivery is not possible in deep set eye, rigid pupil, pseudoexfoliation and inadequately opened eye. In such situation visco delivery or vectis delivery is done while holding the eye at 5-6 clock hour position with one hand and delivery done with other. Nucleus delivery is more difficult in left eye. After this posterior chamber (IOL) is implanted into bag (Figure 8).

Discussion The concept of cataract surgery was given by the famous Indian physician Sushruta (6th century BC), who described it in his work the Sushruta Samhita.1 In the 1940s Harold Ridley introduced the concept of implantation of the intraocular lens.2 In 1967, Charles Kelman introduced phacoemulsification, a technique that uses ultrasonic waves to emulsify the nucleus of the crystalline lens. Self-sealing cataract incisions were mentioned by Kratz et al3 in 1980 and by Girard in 1984.4,5 Kratz thought of scleral tunnel as an astigmatic neutral way of entering the anterior chamber. In 1984, it was shown by Thrasher et al that a 9.0-mm posterior incision induces less astigmatism than a 6.0-mm limbal incision.6 In 1990, Michael McFarland developed a sutureless incision7 and Pallin8,9 described a Chevron shaped incision. During the same period Singer10 popularized the frown

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incision. The supero-temporal location of the incision is far from the two primary meridians (vertical or 90o and horizontal or 180o) of cornea. So any flattening of cornea due to scarring affects the corneal curvature equally so lesser chances of astigmatism in comparison to the incision along the primary meridian. When incision is located superiorly, both gravity and eyelid blinking tend to create a drag on the incision. These forces are better neutralized with temporal incision because it is parallel to the vector of the forces. Superior temporal incision is also free from the effect of gravity and eye lid pressure and tends to induce less astigmatism.11 With the use of this technique overall surgical time is reduced to 5-8 minutes by eliminating three surgical steps - superior rectus stitch, conjunctival flap and cautery. There are also no chances of postoperative ptosis as superior rectus suture is not applied. The healing of incision is also very fast as conjunctival vessels are patent and epithelialisation covers the clean incision site quickly. This technique is being done in our set up for last four to five years with good comfort and visual outcome. A supero-temporal tunnel of 5.5 mm is constructed in right eye and superonasally in left eye. The surgically induced astigmatism (SIA) is minimal (less than one diopter) whereas our superior scleral incision always gave this value above 1D. When the tunnel length exceeded beyond 5.5 mm the astigmatism was noted (unpublished data). There is hardly any contraindication to this procedure but for beginners some situations like deep set eyes and narrow palpebral fissure, non dilating pupil, pseudoexfoliation, hypotony, bleeding tendencies (hypertension, patients on anticoagulants) are relative contraindications. The surgery is performed under peribulbar block using the same size and type of incision (straight to slight frown). Nucleus delivery is done by hydro-expression, visco-expression, or by irrigating vectis depending upon the comfort of expression one can choose either of the three. The site supero-temporal (right) or supero-nasal (left) incision was chosen because there is more space on sides than superiorly because superior rectus suture is not applied. Planes of incision and intraocular manipulations are more accurate as eye is straight rather than in down gaze as in superior rectus stitch. The superior rectus stitch

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application is a blind procedure and difficult for some particularly beginners; so it invariably leads to bleeding, subconjunctival haemorrhage, damage to muscle tendon and rarely perforation. Patient has less tissue trauma, less pain and no chance of surgical ptosis post operatively. So this technique is recommended for all those surgeons who are doing SICS routinely and this will further refine their technique.

References 1.

Sharma PV, Suśruta-Samhitā. Vol II. Varanasi, India: Chaukhambha Visvabharati Oriental Publishers & Distributors: 2001. 2. Apple DJ, Sims J. Harold Ridley and the invention of the introcular lens. Surv Ophthalmol 1996; 40(4):279-92. 3. Kratz RP, Colvard DM, Mazzocco TR. Clinical evaluation of the terry surgical keratometer. Am Intraocular Implant Soc J 1980; 6:249–51. 4. Girard LJ, Hofmann RF. Scleral tunnel to prevent induced astigmatism. In: Emery JM, Jacobson AC, editors. Current concepts in cataract surgery: Proceedings of the eight biennial cataract surgical congress Norwalk. Appleton-Century- Crofts;1984. pp. 101–2. 5. Girard LJ. Origin of the Scleral tunnel incision. J Cataract Refract Surg 1995; 21:7. 6. Thrasher BH, Boerner CF. Control of astigmatism by wound placement. J Am Intraocul Implant Soc 1984; 10: 176–9. 7. Mcfarland M. Surgeon Undertakes Phaco, Foldable IOL series sans sutures. Ocular Surgery News.1990:1. 8. Pallin SL. Chevron incision for cataract surgery. J Cataract Refract Surg 1990; 16: 779–81. 9. Pallin SL. Chevron sutureless closure: A preliminary report. J Cataract Refract Surg 1991; 17:706–9. 10. Singer JA. Frown incision for minimizing induced astigmatism after small incision cataract surgery with rigid optic intraocular lens implantation. J Cataract Refract Surg 1991; 17:677–88. 11. Gokhale NS, Sawhney S. Reduction in astigmatism in manual small incision cataract surgery through change of incision site. Indian J Ophthalmol 2005; 53:201–3.

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