SICS An Alternative to Phaco
RC Nagpal, Manisha Rathi, Sumit Sachdeva

INTRODUCTION
Modern cataract surgery, in which the cataract is actually extracted from the eye, was introduced by Jacques Daviel in Paris in 1748.  Daviel advocated a form of extracapsular surgery in which the inner lens contents were removed from the eye, but a portion of the lens capsule or outer covering and the zonules that attached to it were left in place.  Samuel Sharp of London introduced the concept of intracapsular cataract surgery in 1753 by using pressure with his thumb to remove the entire lens intact through an incision. Small suction cups (erysiphakes) were introduced for this purpose in 1902 as well as various capsular forceps to grasp the lens for removal.1

The techniques and materials historically developed for cataract surgery, in particular the rapid improvements of recent decades, have made possible the miracle of modern cataract surgery.  Today, patients can have their cataracts safely removed as an outpatient procedure, under local anesthesia, with the implantation of a sophisticated intraocular lens calculated to correct their vision, and can resume their normal activities in a matter of days.1

While the conventional cataract surgery had disadvantages like large incision, multiple sutures, and induced astigmatism, newer techniques like phacoemulsification and small incision cataract surgery come into vogue.  The scleral tunnel incision was introduced in early eighties in an attempt to provide better wound healing with less surgically induced astigmatism.  This has become the most favoured incision technique in the recent past for suture less, small incision, non-phaco cataract surgery. Although the length of external incision in this techniques varies from 5mm to 7mm, it is still called small incision cataract surgery (SICS) since the architectural design of SICS renders a suture less, self sealing property to this incision.  The incision of ECCE in contrast to SICS is approximately 12mm at the posterior limbus and requires a number of sclerocorneal stitches.2

Surgery has evolved from being just a small incision technique for cataract extraction to being a sutureless way of ending the procedure, thereby causing minimal distortion to the corneal curvature. So, all the vital parameters that go into the creation of a reproducible, leak proof and atigmatically neutral incision have assumed great importance today.2

METHODS
This study is a retrospective review of 120 cases operated by a single surgeon.  All the patients had immature senile cataract and underwent Manual SICS through superior scleral tunnel incision.  The group was followed up for a period of two months.  The surgery was evaluated in terms of ease of operation, per-operative and post-operative complications, visual outcome, and astigmatism.

SURGICAL TECHNIQUE
Under full asepsis, peribulbar anaesthesia was given.  A superior rectus bridle suture and an eye speculum was applied.  A fornix based conjunctival flap was raised.  A 5.5 mm frown shaped incision was made and scleral tunnel was made superiorly was to help of a crescent knife.  The anterior chamber was entered with a 3 mm keratome, and formed with sterile air.  2 drops of trypan blue dye was instilled under the air bubble in the chamber to stain the anterior capsule.  The dye and the air were washed out and the chamber formed with 2% methylcellulose.  Continuous curvilinear capsulorrhexis was formed using  a 30 G bent needle and hydrodissection and hydrodelineation was done.  The nucleus was rotated and prolapsed into the anterior chamber, and then delivered using an irrigating wire vectis (viscoexpression).  The remaining cortical matter was aspirated using a 2-way I&A cannula.  A rigid PCIOL was implanted in the capsular bag.  Conjunctiva was reposited back and wet field cautery done to anchor it in its position.

POSTOPERATIVE EVALUATION
Post operative evaluation was done at 1 day, 1 week, 4 weeks and 8 weeks and included a detailed examination including vision. keratometry, slit lamp biomicroscopy, and intraocular pressure mesurement.

The cylinder was taken to be the difference of vertical and horizontal K-readings (pre-operative and post- operative) was calculated, and the axis was of the higher K-reading.  This was then converted to Cartesian coordinates using the following formula3.  

x= Cylinder*cos(2*axis)

y= Cylinder*sine(2*axis)

Pre-operative Cartesian coordinates were subtracted from the post operative values, and this difference was taken as X and Y respectively.  To convert the Cartesian coordinates back to standard polar notation for astigmatism, we used the following formula:

Cylinder = Ö X2 + Y2

Angle=1/2* Arc tan (Y/X)

If X & Y>0, then axis = angle

If X<O, then axis=angle+90o

If X>O & Y<O, then axis = angle + 180o

RESULT AND DISCUSSION
The data was analyzed and it was observed that out of 120 patients who were taken up for this study, 70 patients had against the rule astigmatism of 1.57D, and 50 patients had with a rule astigmatism of 1.25 D at the end of 2 months.  There was no significant per-operative complication.  In 3 patients, premature entry into the anterior chamber occurred while forming the tunnel, and in one patient there occurred a rent in the posterior capsule.  Post operatively, striate keratitis was observed in 25% patients, which resolved within 1-2 days.  Most of the patients (98.3%) had a post-operative visual acuity from 6/12 to 6/6.

CONCLUSION
We have found that the Manual SICS is a very safe, effective and economical alternative to phacoemulsification with comparative results in terms of visual acuity, astigmatism, and wound stability, without having the inherent drawbacks of the latter, namely, high cost of surgery, relatively lesser margin of safety, and a steep learning curve.

REFERENCES

  1. Cataract surgery in modern era [online]] [cited September 4].  Available from: URL: http://www.eyecareamerica.org/eyecare/museum/exhibits/online/cataract/modern.cfm

  2. Kamaljeet Singh. History of cataract surgery, Surgical aspects Un Small incision cataract surgery (Manual Phaco) 1sted., Jaypee Brothers, 2002, 4-8, 75-83.

  3. Holladay JT, Dudeja Dr. Koch DO. Evaluating and reporting astigmatism for individual and aggregate data. J cataract refract Surg 1998;24: 57-65.

Address for Correspondence
Dr. R.C. Nagpal, Deptt. of Ophthalmology,
Pt. BD Sharma, PGIMS, Rohtak