(India)
(India)
(India)
INTRODUCTION
Cataract is the main cause of avoidable blindness worldwide, with the developing world accounting for three quarters of blindness.1 Despite the 10 to 12 million cataract operations performed globally, cataract blindness is still thought to be increasing by 1 to 2 million/year.2 In order to effectively address this increasing backlog, significant efforts are being undertaken to increase the output of cataract surgical services in many developing countries3 and to make cataract surgery affordable to all people irrespective of their economic status. The transition from intracapsular cataract surgery to extracapsular surgery with IOL implantation has effected a dramatic change in the postoperative visual outcome, quality of life and increased acceptance of surgical intervention by the community.
OBJECTIVES
The main objective in modern cataract surgery is to achieve a better-unaided visual acuity with rapid post-surgical recovery and minimal surgery related complications. Early visual rehabilitation and better-unaided vision can be achieved only by reducing the incision size. The size of the incision in turn depends on mode of nucleus delivery and type of intraocular lens (rigid or foldable). In standard extra capsular cataract extraction, the incision needs to be 10 to 12 mm for safe delivery of nucleus. In manual small incision cataract surgery (SICS) it is between 5.5 and 7 mm and in instrumental phaco it varies from 3 mm to 6 mm depending on the technique and implant. The use of smaller incision with advantages of faster rehabilitation, less astigmatism and better postoperative 3vision without spectacles led to phacoemulsification becoming the preferred technique where resources are available.
Despite excellent facilities and skilled surgeons, the poor in the developing world are even deprived of the visual benefits of the IOL because of their inability to afford them.4 With this background phacoemulsification with all its benefits may not be an affordable technique due to the cost involved in the developing countries. Alternatively manual SICS with its relatively smaller incision has similar advantages to phacoemulsification and is affordable.
Manual SICS has evolved as an effective alternative to phacoemulsification in the present times. Recent studies have proved that Manual SICS is cost-effective and has more benefits than conventional ECCE.5 To list a few of them are as follows:
- Better and early wound stability
- Less post operative inflammation
- Can avoid suture and suture related complications (e.g. iris prolapse, suture infiltrate, bleeding)
- Less postoperative visits
- Early reduction and stability of surgically induced astigmatism.
Moreover, manual SICS can be performed in almost all type of cataracts in contrast to phacoemulsification where case selection is extremely important for an average surgeon. The duration of surgery and phaco power varies with the nucleus density, as also the incidence of intraocular complications, where as in manual SICS, the time spent on nucleus delivery does not vary from case to case. In cataracts with dense nuclei, with the incision enlarged to 7 mm, the nucleus can be delivered with an irrigating 4vectis. An alternative technique for extraction through a smaller wound is by phacosandwich technique. This is a bimanual technique where under the cover of viscoelastics the nucleus is delivered bimanually with a vectis and Sinskey hook. Phacofracture is another technique used in manual SICS to bring out nuclei of varying grades through a smaller tunnel up to 4 or 5 mm.
Hypermature cataracts with liquefied cortex and hard nuclei can get excellent results with manual SICS. To handle hypermature cataracts in phaco becomes difficult because of the fibrosed capsule, weak zonules, hard mobile nucleus etc. Again traumatic cataracts following penetrating trauma, colobomas, cataract following RD surgery, etc. are better tackled by this procedure.
Capsulorhexis is mandatory for phaco but manual SICS can also be done with the canopener technique. In a study where the learning curve in residents learning phaco was analyzed four patients had to convert to extra capsular cataract extraction and in three patients the reason for ‘bailing out’ was the absence of an intact rhexis6. In MSICS the conversion to ECCE due to an absence of capsulorhexis is not necessary as the nucleus is delivered comfortably even with a canopener capsulotomy.
Incidence of intraoperative complications like posterior capsule rupture is less common in MSICS when compared to phaco. Yet another recent study compared the safety of ECCE, MSICS and phaco and reported a lower intraoperative and immediate postoperative complication in the MSICS group when compared with the rest.7 Certain phaco related complications such as corneal burns due to the phaco probe and iris chaffing are not encountered in manual SICS. The endothelial cell counts on this subgroup of patients are no different from those 5who have had phacoemulsification.8 Endothelial cell loss in phaco depends on the density of the nucleus9 in contrast to manual SICS where the skill of the surgeon plays an important role.
Published evidence points out that surgically induced astigmatism following ECCE is 3.91 times higher than MSICS.6 Their results show that the difference in surgically induced astigmatism between MSICS and phaco with rigid IOL was not statistically significant. Implantation of foldable IOL though a standard procedure in the developed countries, is used only among the affluent society in developing countries. This is because the foldable IOL costs as much as 10 times as that of a rigid IOL. The final visual acuity between these two groups is also comparable. Our own unpublished data shows that the final postoperative visual acuity in both MSICS and phaco are similar.
Surgical time in phacoemulsification is dependent on the type of cataract. In a study performed in a rural eye camp in India manual SICS was performed within 3.8 to 4.2 minutes.7 Being a faster procedure, manual SICS can be performed in a high volume set up. In an Indian study where cost comparison between the two procedures was done, the average cost for the provider was US$15.82 for ECCE and US$15.68 for SICS.10 Both these surgeries are thus economical. Yet another study points out the cost to be US$17 for ECCE, US$18 for MSICS and US$26 for phacoemulsification.6 Though the provider costs are similar for MSICS and ECCE, Patient's costs might be lower for SICS patients considering the fewer postoperative medications, follow-up visits and spectacles and the total cost may thus work out to be more economical. Another major advantage of manual SICS is that, it is not a machine dominated procedure The 6surgical skills and experience of the surgeon play a significant role in the results. Also considerable expense in acquiring and maintaining a machine is not required.
Transition to phacoemulsification is easier if one has mastered Manual SICS, as he is familiar with steps such as scleral pocket incisions, capsulorhexis, hydroprocedures etc. Familiarity with these steps helps reduce the incidence of complications while learning phaco.11 There are instances where we have to convert form phacoemulsification to extra capsular cataract surgery. One study reports the conversion rate from phaco to extra capsular by an experienced surgeon to be 3.7%.12 Converting to an extra capsular result in a larger, unstable wound than manual SICS. If one is familiar with the manual nucleus delivery technique with the self-sealing wound one can reduce suture induced astigmatism and other complications.
Phacoemulsification being an expensive technique cannot be employed as the standard procedure in developing countries with a cataract backlog and is a strain on the economy. High quality, high volume cataract surgery has been popularized in eye care centers in India to effectively manage the large backlog of cataract blindness.13
In an era where advances are linked to expensive innovative technology, it is exciting to witness the evolution of simplified, low cost alternatives. Manual small incision cataract surgery offers the smaller incision size of phacoemulsification and the added advantage of not requiring expensive equipment. Manual SICS offers all the merits of phacoemulsification with the added advantages of having wider applicability, better safety, with a shorter learning curve and lower cost.7
REFERENCES
- Thylefors B, Negrel AD, Pararajasegaram R, et al. Global data on blindness: an update. Bull World Health Organ 1995;73:115–21.
- World Health Organisation. Global initiative for the elimination of avoidable blindness. WHO, Geneva: WHO/PBL/97;61.
- Limburg H, Vasavada A, Muzumdar G, et al. Rapid assessment of cataract blindness in urban district of Gujarat. Indian J ophthalmol 1999;47:135–41.
- Malik AR, Qazi ZA, Gilbert C. Visual outcome after high volume cataract surgery in Pakistan. Br J Ophthalmol 2003;87:937–40.
- 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):843–46.
- Muralikrishnan R, Venkatesh R, Babu B Manohar, Prajna N Venkatesh. A comparison of the effectiveness and cost effectiveness of three different methods of cataract extraction in relation to the magnitude of postoperative astigmatism. Asia Pacific J Ophthalmology 2003;15:5–12.
- Balent LC, Narendran K, Patel S, Kar S, Patterson DA. High volume sutureless intraocular lens surgery in a rural eye camp in India. Ophthalmic Surg Lasers 2001;32(6):446–55.
- Mathew Ana, et al. Manual nucleo fragmentation and endothelial cell loss J Cataract Refract Surg 1997;23:995–99.
- Hayashi K, Hayashi H, Nakao F, Hayashi F. Risk factors for corneal endothelial injury during phacoemulsification. J Cataract Refract Surg. 1996;22(8):1079–84.
- 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):843–46.
- Thomas R, Naveen S, Jacob A, Braganza A. Visual outcome and complications of residents learning phacoemulsification. Indian J Ophthalmol 1997;45(4):215–19.
- Natchiar G, Robin AL, Thulasiraj R. Attacking the backlog of India's curable blind: the Aravind Eye Hospital model Arch Ophthalmol 1994;112:987–93.