6.
6.1 / BRIEF RESUME OF INTENDED WORK
NEED FOR STUDY
The main goals of modern Cataract surgery are:
  1. Early visual rehabilitation by giving near normal vision
  2. Minimal induced post operative astigmatism
  3. Rapid patient mobilization
  4. Cost effectiveness in developing countries like India
To meet these objectives, cataract surgery should be performed using a small incision. The smaller the incision, the smaller the residual post operative astigmatism. The size of the incision in turn depends on the mode of nucleus delivery.
The advantages of manual small incision cataract surgery (SICS) are universal applicability, short operating time, cost effectiveness, sutureless incision, lesser surgical complications and short learning curve. The incision size is between 5.5 to 7mm.
During manual SICS, different techniques can be used to remove the nucleus: either hydroexpression alone (using an anterior chamber maintainer), hydrodissection plus extraction (using an irrigating vectis or Simcoe cannula) or extraction alone (using a fish hook needle). The methods which involve nucleus division and its subsequent removal include phacofracture using wire vectis/ bisector / trisector, multiple phacofragmentation, phacopunch, Jaw’s slider pincer technique, nylon phacosection etc.
Problems with the different techniques are mainly related to the size of the tunnel and the proximity of the nucleus to the corneal endothelium. While delivering the nucleus through the tunnel, accidental contact between the nucleus and the corneal endothelium must be avoided. Otherwise post operative corneal oedema and sometimes even corneal decompensation may occur.
Today, with the development of small incision cataract surgery, many patients are experiencing a faster recovery and a quicker return to good vision.
6.2 / REVIEW OF LITERATURE
Cataract opacification of the lens is one of the commonest causes of loss of useful vision with an estimated 16 million people affected worldwide. Increasing age is an important risk factor. No method to halt the formation of a cataractous lens has been shown to be effective.1
A huge backlog of cataract blindness exists in the developing world. It is estimated that 3.8 million people develop blinding cataract every year in India, as against 2.7 million cataract surgeries done every year.2
In the late 1960s and early 1970s, Dr. Charles Kelman pioneered the technique of removal of a cataractous lens through a small incision using phacoemulsification technique.
During the early 1980s when a self sealing tunnel incision was introduced in USA, surgeons developed instruments and techniques to cut the nucleus into parts for easy removal through a smaller self sealing sclerocorneal tunnel.3
In 1983, Gerald Keener used a nuclear snare to divide the nucleus into 2 halves.
Luther. L. Fry first attempted the Phacosandwich technique in 1985. He actually tried to bisect the nucleus inside the anterior chamber using a standard lens loop and an iris spatula. In the process, he discovered that by squeezing the nucleus between these two instruments, it could be extracted through a smaller wound.
For cases with nuclear sclerosis Grade 3 and 4, Peter Kansas introduced the technique of Phacofracture in 1988 using a bisector or trisector splitting the nucleus into 2 or 3 parts.4
In 1990, Blumenthal introduced the Blumenthal technique which follows the concept of Hydrodynamic delivery of the nucleus. The fish hook extraction was developed in Lahan, Nepal in 1997.
Manual SICS is an excellent technique with low cost, less complications and quality vision. Softer the cataract, better is the visual acuity and least is the astigmatism. Harder the cataract, larger inner corneal wound and greater the astigmatism. In the bag IOL gives more physiological position with least astigmatism.5
6.3 / OBJECTIVES OF THE STUDY
1.To study the early post operative corneal complications arising from the 4 techniques of nucleus expression
2.To study the resultant post operative visual acuity from the 4 techniques of nucleus expression
7.0 / MATERIALS AND METHODS:
7.1 / SOURCE OF DATA:
Patients with senile cataract undergoing cataract surgery at MSRMTH, Bangalore from 1st November 2008 to 30th April 2010
7.2 / METHOD OF COLLECTION OF DATA:
Sample size:
100 patients selected from 1st November 2008 to 30th April 2010, randomly chosen to undergo the following standard techniques of nucleus expression of manual SICS:
  1. Phacosandwich technique - 25 patients
  2. Viscoexpression technique - 25 patients
  3. Phacofracture technique - 25 patients
  4. Irrigating Vectis technique - 25 patients
Inclusion Criteria:
  1. Senile cortical cataract
  2. Nuclear cataract Grade I and Grade II
  3. Senile cataract with metabolic diseases like Diabetes mellitus and Hypertension are also included in the study
Exclusion Criteria:
  1. Nuclear Sclerosis Grade III and Grade IV
  2. Presenile, complicated and traumatic cataracts
  3. Pseudoexfoliation syndrome
  4. Corneal opacities due to degeneration/ dystrophies/ infective or inflammatory disorders
  5. Glaucoma
  6. Miotic pupil
  7. Intraoperative complications like vitreous loss, Iris prolapse

Methodology:
Pre operative assessment:
  • Written consent will be taken from each patient
  • Detailed History and general examination
  • Visual acuity
  • Torch light examination
  • Slit lamp examination
  • Direct ophthalmoscopy
  • Indirect ophthalmoscopy
  • Retinoscopy
  • Intraocular pressure by applanation tonometry
  • Syringing
  • Keratometry
  • A scan for calculation of IOL power using SRK formula
  • Fasting Blood Sugar to assess Diabetic status
Operative procedure:
Manual small incision cataract surgery is performed under peribulbar anaesthesia using one of the following methods of nucleus expression:
  1. Phacosandwich technique: Nucleus is sandwiched in between the Lens Dialer and the Vectis and brought out of the wound without touching the corneal endothelium.
  2. Viscoexpression technique: Nucleus is expressed by injecting viscoelastic substance into the anterior chamber and opening up the scleral tunnel by pressing over the posterior lip of the scleral tunnel opening.
  3. Phacofracture technique: Nucleus is broken into smaller pieces by 2 instruments (like the irrigating vectis and nucleotome) and viscoexpressed out.
  4. Irrigating vectis technique: Hydroexpression with an irrigating vectis uses a combination of mechanical and hydrostatic forces to express out the nucleus.
Post operative follow up:
Follow up at Day 1 and Day 7 will include
  • Visual acuity
  • Torch light examination
  • Slit lamp examination of conjunctiva, cornea and lens
  • Pachymetry and Specular microscopy in patients having corneal haziness or oedema
Statistical analysis:
Chi square test for comparison of corneal complications and ANOVA test for comparison of visual acuity by the 4 different techniques
7.3 / Does the study require any investigations or interventions to be conducted on patients or other humans or animals?
Yes, as mentioned in 7.2. There is no financial interest involved in the study either to the manufacturers of surgical equipments or materials and no extra financial burden to the patient
7.4 / Has ethical clearance been obtained from your institution in case of 7.3
Yes
8 / Bibliography
  1. Asbell A, Dualan, Mindel, Brocks, Ahmad M, Epstein Seth “Age related cataract” The Lancet 2005 Feb; 365(9459): 599-609
  2. Gogate, Deshpande, Wormald “Is manual small incision cataract surgery affordable in the developing countries? A cost comparison with extra capsular cataract extraction” British J of Ophthalmology 2003 July; 87(7): 843-46
  3. Hennig Albrecht “Sutureless non-phaco cataract surgery. A solution to reduce worldwide cataract blindness.” Community eye health journal 2003; 16(48): 49-51
  1. Basti S, Vasavada AR, Thomas R, Padhmanabhan P. Extracapsular cataract extraction : Surgical techniques. Indian J Ophthalmol 1993;41:195-210
  2. Singh A “Study of Astigmatism in 6mm scleral tunnel incision in manual SICS” Journal of International society of manual small incision cataract surgeons; 2007 Dec; 2(2): 33-34