Small Incision Cataract Surgery Tanuj Dada, Anita Panda
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Need for Small Incision Cataract SurgeryCHAPTER 1

 
2The last two decades have seen a technological explosion in the field of ophthalmic surgery. In no other field is this as evident as in the field of cataract surgery. The drive of the cataract surgeon to produce a pseudophakic eye whose optical performance is at par or even exceeds that of a normal phakic eye has reached a new peak. In addition there is an increasing demand from cataract patients for quick rehabilitation. In the West the emphasis has shifted to phacoemulsification and microincision cataract surgery with use of high tech machinery and expensive instrumentation. However, this is an expensive proposition and requires high level of surgical training. For the developing countries which can ill afford such an expensive technology for the masses, small incision cataract surgery (SICS) has come in as the savior, being a simple, effective and safe technology which does not require any special machinery. SICS is the need of the hour and seems to be the appropriate technology for decreasing the burden of blindness in our population and achieving the goals set under the Vision 2020 Program.
“The Right to Sight” is the common global agenda launched by the WHO and a task force of International NGOs to combat the gigantic problem of blindness and the aim of Vision 2020 is to reduce the current expected 75 million blind people to 25 million by the year 2020. Cataract is the major cause for blindness with an estimated 16-20 million people being bilaterally blind due to the disease and this number is exponentially increasing with the population explosion coupled with the increased life expectancy. Against this colossal figure for cataract 3blindness, the global annual figure of total cataract surgery is only about 7-8 million. The problem of blindness is more magnified in Africa and Asia, where at least one person per 1000 population goes blind from cataract. This incidence transfers to about 900,000 new cases in India every year and of the 15 million blind in India, 80% are due to cataract. Thus there is an urgent need of enhancing the cataract surgical rate to achieve the mark of 32 million per year by 2020 with special emphasis on developing and underdeveloped countries.
To achieve such a goal, one requires a surgery with the following characteristics:
  1. High success rate in terms of restored vision and improved quality of life.
  2. Should be affordable and accessible to all and especially the under privileged.
  3. Can be practiced by majority of the ophthalmic surgeons.
  4. Should not require large inputs in terms of equipments and instruments.
  5. Least time consuming.
  6. Low complication rate.
  7. Minimal postoperative care and follow-up.
At the current time manual SICS appears to satisfy all these criteria. It can be performed for all types of cataracts and in every ophthalmic theater including a rural camp site, is cost effective, least time consuming and has a short learning curve. It has thus become the surgery of choice in developing and under developed countries for high volume cataract surgery. The advantages of manual SICS are outlined in Tables 1.1 and 1.2.
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Table 1.1   Advantages of SICS as compared to conventional ECCE
  1. Shorter surgical time
  2. Small incision
  3. Less scleral scarring
  4. Less conjunctival scarring
  5. Faster healing of scleral incision
  6. Overall recovery of patient is faster
  7. Eye is physically stronger in the postoperative period
  8. Less astigmatism induced
  9. Easier control of postoperative astigmatism
  10. Deeper posterior chamber allows shorter, more complete cortical clean-out
  11. No/minimal need for sutures
  12. More control and safety in event of expulsive choroidal hemorrhage
  13. Less chance of posterior capsule tear with deeper chamber
  14. Safer intraocular lens insertion due to small incision
  15. Easier chamber control allows more reliable capsular intraocular lens insertion
  16. Small incision and maintenance of anterior chamber allow for better vitreous pressure control
  17. Less vitreous disturbance and less vitreous loss in event of capsular tear
  18. Easier vitreous clean-up in event of vitreous loss
  19. Shorter retinal exposure to microscope light
  20. Quieter eyes postoperatively
  21. Fewer postoperative steroids required
  22. Less cystoid macular edema
  23. Can now be performed under topical anesthesia
  24. In the event of a posterior capsule rupture, IOL can be placed over the capsulorhexis
  25. Decreased chance of endophthalmitis due to a closed chamber surgery
 
ESSENTIALS FOR TRANSITION
Initial cases should be carefully selected and the transition from planned extracapsular cataract extraction to manual SICS must be gradual so that the surgeon is confident of each step he is to undertake.
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Table 1.2   Advantages of SICS as compared to phacoemulsification
  1. It is cost effective as dose not depend on a sophisticated machine
  2. No expensive infrastructure is required
  3. No special instruments are required
  4. Short learning curve
  5. Less surgical expertise
  6. No chance of nuclear drop into vitreous
  7. Decreased endothelial loss in supra hard cataracts
  8. Can be completed in the event of power loss or machine failure
  9. Not dependent on highly trained maintenance personnel
  10. Feasible for all types of nuclei
  11. No hand foot co-ordination is required
  12. Decreased overall risk of complications
  13. Faster surgical time in expert hands
  14. No chance of wound burn
There are three essential issues that need to be addressed for a painless transition, i.e: (a) The surgeon (b) The patient (c) The instrumentation.
 
 
The Surgeon's Ability
Although the surgeon is the chief architect in ensuring the success of SICS, any eye surgeon can learn how to perform a good SICS. Only when he has been routinely performing planned extracapsular cataract extraction under an operating microscope with a low rate of posterior capsular rents, is completing the surgery safely and relatively quickly, should he convert to SICS. He should be ambidextrous. During his routine extracapsular cataract 6extraction, he should become proficient in capsulorhexis, hydrodissection, automated irrigation and aspiration. One should also attend wet labs and practice surgery on animal eyes to gain proficiency in the SICS procedure.
 
Selection of the Patient
The eye should be free from any other ocular disease; cataract should have a nucleus of moderate hardness, pupillary dilation should be adequate, visualization should be excellent with a good red glow and the eye should not be very deep set. Preoperative examination should pay more emphasis on:
  1. Pupillary dilation
  2. Age of the patient and hardness of lens nucleus
  3. Status of corneal clarity, corneal endothelial count
  4. Pseudoexfoliation
  5. Zonular deficiency
  6. Depth of the anterior chamber
  7. Evidence of any extraocular infective focus
  8. Any macular disorder which may be the cause for the decreased visual acuity.
The ideal candidates are patients with a moderately hard cataract who are aphakic in the other eye. One should not select a patient with a poor visual acuity in the fellow eye during the learning phase.
 
Instrumentation
Although no special instrument is required one can facilitate surgery by having a good crescent knife for 7making the corneoscleral tunnel, keratome to enter the anterior chamber, capsulorhexis forceps, using an anterior chamber maintainer and using special spatulas and nucleus bisectors/trisectors.
 
Phases of Conversion
These would include the following four phases:
 
Phase I: Gaining Adequate Know-How
This can be achieved by reading books, seeing surgery video tapes, attending wet labs and courses. All these are a must but performing the procedure on animal eyes needs to be emphasized strongly.
 
Phase II: Steps to be Learnt while Performing Extracapsular Surgery
Even prior to actually starting the SICS procedure, certain surgical maneuvers can be mastered during routine extracapsular cataract extraction. These include performing scleral/corneal dissection, capsulorhexis, hydrodissection and learning the art of nucleus rotation out of the capsular bag.
 
Phase III: Early Conversion
During this phase one should concentrate on getting a feel of SICS by converting your ECCE to SICS by making a short tunnel at the limbus and doing the nuclear prolapse and expulsion using a vectis. During this phase one should not attempt to have a sutureless incision but only try and establish the various techniques of tackling the nucleus.
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Phase IV: Total Conversion
Once the surgeon has practiced a small incision ECCE with proper wound construction, nucleus prolapse out of the capsulotomy and learnt how to deliver out the nucleus without complications, it is time to fully convert to SICS. It is only in this phase that total conversion should be attempted. One should now gain proficiency in constructing a sutureless wound, handling various types of nuclei and gaining consistency in the results.
 
Cost of Surgery
The cost of doing manual SICS is much lower than phacoemulsification and comparable to ECCE. Hence it is best suited for developing countries and for a high volume camp surgery. Muralikrishnan et al from Aravind Eye Hospital evaluated the direct and indirect costs of three cataract surgery procedures: extracapsular cataract extraction with intraocular lens implantation (ECCE-IOL), phacoemulsification (Phaco) and manual small incision cataract surgery (MSICS) using economic costing principles. The average unit cost for each surgical procedure was calculated from the societal perspective using economic costing methods. Total annual provider's direct costs for each input to surgery were calculated and apportioned appropriately to different cataract surgery techniques using a “micro-costing approach”. The patient's direct and indirect costs for each procedure were calculated by interviewing staff and patients and by using assumptions about prices for relevant cost items such as 9transportation, food, medicine, spectacles and economic productivity loss. The Average provider's direct costs were highest for Phaco procedures (25.55 US Dollars) compared to MSICS (17.03 US Dollars) and ECCE-IOL (16.25 US Dollars). The difference can be attributed to the cost of equipment and materials. Average direct and indirect patient costs were highest for ECCE-IOL (19.85 US Dollars), while the costs for Phaco and MSICS were identical (12.37 US Dollars). ECCE-IOL had the highest total costs and MSICS had the lowest total costs from the societal perspective. The study concluded that MSICS may have a lower societal cost than other options. Considering the small incremental cost for providers (less than 1 US Dollar), improved outcomes, and lower patient costs, the authors recommended that MSICS is an important technique to use in efforts to eliminate cataract blindness in India and this result may be generalized to other developing countries.
Gogate et al compared the cost of manual small incision cataract surgery (MSICS) with conventional extracapsular cataract surgery (ECCE) in community eye care settings. A single masked randomized trial was used to compare the safety, efficacy, time, and patient satisfaction of surgery by both the techniques. The fixed facility and recurrent cost for the two procedures was calculated based on information collected from different sources. Average cost per procedure was calculated by dividing the total cost by the number of procedures performed. The average cost of an ECCE procedure for the hospital was Rs. 727.76 (US $15.82) and the average cost of a MSICS procedure was Rs. 721.40 10(US $15.68), of which Rs. 521.51 (US $11.34) was the fixed facility cost common to both. The study concluded that both ECCE and MSICS are economical in community eye care settings, but MSICS is more economical and gives better uncorrected visual acuity in a greater proportion of patients.
 
Clinical Results of MSICS as Compared to ECCE and Phaco
Various studies have been conducted to evaluate the clinical results of MSICS as compared to conventional ECCE and phacoemulsification. Gogate et al evaluated the role of MSICS for the rehabilitation of cataract visually impaired and blind patients in community based, high volume, eye hospital setting and compared the safety and effectiveness of MSICS with conventional extracapsular cataract surgery (ECCE). In a single masked randomized controlled clinical trial, 741 patients, aged 40-90 years, with operable cataract were randomly assigned to receive either MSICS or ECCE and operated upon by one of eight participating surgeons. The patients were followed up at 1 week, 6 weeks, and 1 year after surgery and their visual acuity recorded. 706 of the 741(95.3%) patients completed the 6 weeks follow-up. 135 of 362 (37.3%) of ECCE group and 165 of 344 (47.9%) of MSICS group had uncorrected visual acuity of 6/18 or better after 6 weeks of follow-up. 314 of 362 (86.7%) of ECCE group and 309 of 344 (89.8%) of MSICS group had corrected postoperative vision of 6/18 or better. Four of 362 (1.1%) of ECCE group and six of 344 (1.7%) of MSICS group had corrected postoperative visual acuity less than 6/60. There were no significant differences between the 11two groups for intraoperative and severe postoperative complications. The conclusion of the study was that MSICS and ECCE are both safe and effective techniques for treatment of cataract patients in community eye care settings. MSICS needs similar equipment to ECCE, but gives better uncorrected vision.
Guzek and Ching evaluated the results of small incision manual extracapsular cataract extraction surgery in a district hospital in West Africa. This prospective study consisted of 200 eyes of 193 patients who had small incision manual ECCE between January 1999 and May 2000. For comparison, the charts of 32 patients (32 eyes) operated on between July and December 1998 using a limbal incision (control group) were retrospectively analyzed. Outcome measures included intraoperative and postoperative complications, postoperative visual acuity, and refractive astigmatism. In the small incision ECCE group, self-sealing wounds were achieved in 129 eyes (64.5%). Vitreous loss occurred in approximately 3% of eyes in both the small incision and control groups. The final visual acuities were similar between the 2 groups, with more than 90% of eyes in both groups achieving a final best corrected visual acuity of at least 20/60. Eyes in the small incision group had faster visual recovery (P < 0.001), a lower incidence of fibrinous iritis (P = 0.02), and were more likely to have round pupils (P < 0.001) than eyes in the control group. The main complication of small incision surgery was moderate corneal edema, which persisted until at least the 1 week visit in 14 eyes (7%). The authors concluded that small 12incision manual ECCE surgery yielded faster visual rehabilitation and had a lower incidence of fibrinous iritis than standard ECCE surgery.
Sharma et al performed an assessment of the results of small incision cataract surgery with intraocular lens implantation using an anterior chamber maintainer (ACM). A retrospective audit was performed of all 300 consecutive patients who underwent extracapsular cataract extraction using a 6 mm scleral tunnel incision, anterior chamber maintainer and manual fragmentation of the nucleus. Ninety percent of patients had a gain in visual acuity at the end of 3 months. The rate of posterior capsule opacification was comparable to the results of the National Cataract Surgery Survey (RCO 1993), i.e. 13%, but the rate of corneal endothelial decompensation and endophthalmitis was marginally higher. The study concluded that appropriate selection of cases, meticulous wound closure and subconjunctival antibiotics at the end of surgery make MSICS an acceptable alternative small incision closed-system low-cost procedure where phacoemulsification is not available.
Hepsen et al evaluated the safety and efficacy of small incision extracapsular cataract extraction (ECCE) using the manual phacotrisection technique. Fifty-nine eyes of 54 patients had small incision ECCE by the manual phacotrisection technique. Mean follow-up was 10 months. After capsulorhexis and hydrodissection were performed, the endonucleus was prolapsed into the anterior chamber and trisected using an anteriorly positioned triangular trisector 13and posteriorly placed solid vectis. Pieces were extracted with a forceps through a small incision. Postoperatively, best spectacle-corrected visual acuity of 20/40 or better was achieved in 48 eyes (83%) and of 20/25 or better in 28 eyes (47%). The most frequent intraoperative complication was posterior capsule rupture (n = 5). Of eyes that developed posterior capsule rupture, 3 had vitreous loss and 2 had implantation of an anterior chamber intraocular lens (IOL). In 44 eyes, the IOL was implanted in the bag and in 12 eyes, in the ciliary sulcus. The most significant postoperative complication was transient corneal edema, which developed in 32 eyes (54%). No permanent complications (e.g. corneal endothelial decompensation) occurred in any case. The study concluded that manual phacotrisection has several advantages such as nucleus safety, less dependence on assistant personnel, the elimination of the phaco machine, and cost effectiveness.
Duch Mestres et al compared the intraoperative complications of planned extracapsular cataract extraction (ECCE) with those of manual nucleofragmentation. This retrospective study comprised 567 eyes; 444 had planned ECCE and 123,manual nucleofragmentation through a scleral tunnel incision. No significant differences between techniques were found in terms of intraoperative complications (P < 0.05). Manual nucleofragmentation did not increase the risk of intraoperative complications (P < 0.05). The study concluded that although phacoemulsification is the procedure of choice in many cases, manual 14nucleofragmentation is a safe and valid alternative that achieves the goals of small incision cataract surgery.
In a recent study, Gogate et al also compared the efficacy, safety, and refractive errors of astigmatism after cataract surgery by phacoemulsification and manual small incision cataract surgery. In this study a total of 400 eyes were assigned randomly to either phacoemulsification or small incision cataract surgery. One hundred thirty-one of 192 (68.2%) patients in the phacoemulsification group and 117 of 191 (61.25%) patients in the small incision group had uncorrected visual acuity better than or equal to 6/18 at 1 week. One hundred fifty of 185 (81.08%) patients of the phacoemulsification group and 133 of 187 (71.1%) patients of the small incision group (P = 0.038) were better than or equal to 6/18 at the 6 weeks follow-up for presenting visual activity. Visual acuity improved to > or = 6/18 with best correction in 182 of 185 patients (98.4%) and 184 of 187 (98.4%) patients respectively in the two groups. Poor outcome (postoperative visual acuity < 6/60) was noted in 1 of 185 (0.5%) in the phacoemulsification group and none in the small incision group. The mode of astigmatism was 0.5 diopters (D) for the phacoemulsification group and 1.5 D for the small incision group, and the average astigmatism was 1.1 D and 1.2 D, respectively. The phacoemulsification group had 7 posterior capsular rents compared with 12 in the small incision group, but the phacoemulsification group had more corneal edema on the first postoperative day. The authors concluded that both the phacoemulsification and the small incision techniques are safe and effective for visual rehabilitation of cataract 15patients, although phacoemulsification gives better uncorrected visual acuity in a larger proportion of patients at 6 weeks.
Bourne et al conducted a study to investigate whether modern phacoemulsification surgery results in more damage to the corneal endothelium than extracapsular cataract extraction. Five hundred patients, 40 years or older were randomized into 2 groups (ECCE, 249; phacoemulsification, 251). An average 10% reduction in cell count was recorded by 1 year postoperatively. There was no significant difference in overall percentage cell loss between the 2 treatment groups. Factors associated with excessive cell loss (> or =15% by 1 year) were a hard cataract, age and vitreous loss at surgery. Phacoemulsification carried a significantly higher risk of severe cell loss in patients with hard cataracts relative to ECCE with both procedures achieving similar postoperative visual acuity outcomes. The authors concluded that there was an increased risk of severe cell loss with phacoemulsification in patients with hard cataracts and thus phacoemulsification may not be the optimal procedure in these cases.
In conclusion, manual small incision cataract surgery is an excellent, safe and low cost technique for cataract surgery which is most suitable for developing countries. Its visual results are comparable to phacoemulsification and better than conventional extracapsular cataract surgery. It is the surgery of choice for suprahard cataracts, where phacoemulsification may be associated with a high corneal endothelial loss and must be inculcated in training programs for residents of ophthalmology.
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SUGGESTED READING
  1. Bourne RR, Minassian DC, Dart JK, Rosen P, Kaushal S, Wingate N. Effect of cataract surgery on the corneal endothelium: Modern phacoemulsification compared with extracapsular cataract surgery. Ophthalmology 2004;111(4):679–85.
  1. Duch Mestres F, Matheu A, Torres F, Lillo J, Castilla M. Intraoperative complications of planned extracapsular cataract extraction versus manual nucleofragmentation. J Cataract Refract Surg 1996;22(8):1113–5.
  1. Gogate PM, Deshpande M, Wormald RP, Deshpande R, Kulkarni SR. Extracapsular cataract surgery compared with manual small incision cataract surgery in community eye care setting in western India: A randomised controlled trial. Br J Ophthalmol 2003;87(6):667–72.
  1. Gogate PM, Deshpande M, Wormald RP. Is manual small incision cataract surgery affordable in the developing countries? A cost comparison with extracapsular cataract extraction. Br J Ophthalmol 2003;87(7):843–6.
  1. Gogate PM, Kulkarni SR, Krishnaiah S, et al. Safety and efficacy of phacoemulsification compared with manual small incision cataract surgery by a randomized controlled clinical trial: Six weeks results. Ophthalmology 2005;112(5):869–74.
  1. Guzek JP, Ching A. Small incision manual extracapsular cataract surgery in Ghana, West Africa. J Cataract Refract Surg 2003;29(1):57–64.
  1. Hepsen IF, Cekic O, Bayramlar H,Totan Y. Small incision extracapsular cataract surgery with manual phacotrisection. J Cataract Refract Surg 2000;26(7):1048–51.
  1. Muralikrishnan R, Venkatesh R, Prajna NV, Frick KD. Economic cost of cataract surgery procedures in an established eye care center in Southern India. Ophthalmic Epidemiol 2004;11(5):369–80.
  1. Sharma T, Dhingra N, Worstmann T. Audit of small incision cataract surgery using an anterior chamber maintainer. Eye 2000;14:646–50.