Effect of Minimising Ultrasound Power to 1% During Cataract Surgery on Corneal Endothelium.

Cataract Clinical Trial

— OCTOPUS  

Official title:

Standard Coaxial Microincision Cataract Surgery Versus Coaxial Microincision Cataract Surgery Using 1% Ultrasound in Immature Senile Cataract :a Corneal Endothelium Study

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT01259349
• Other study ID #: RMLH-002-EYE
• Status: Recruiting
• Phase: Phase 3
• First received: December 6, 2010
• Last updated: December 14, 2010
• Start date: November 2010
• Est. completion date: April 2012

Study information

• Verified date: November 2010
• Source: Dr. Ram Manohar Lohia Hospital
• Contact: Taru Dewan, MS FRCSEd
• Phone: 0091-9810673180
• Email: tarudewan[@]hotmail.com
• Is FDA regulated: No
• Health authority: India: Indian Council of Medical Research
• Study type: Interventional

Clinical Trial Summary

Coaxial microincision cataract surgery using 1% ultrasound is not inferior to standard coaxial microincision cataract surgery in patients of grade 0.1-6.0 immature senile cataract in terms of corneal endothelial safety.

Description:

Corneal endothelial damage and posterior capsular rupture are two most undesirable complications of cataract surgery, infact significant loss of endothelium can lead to corneal decompensation and loss of corneal clarity. However, some degree of endothelial cell loss is inevitable after any cataract surgery. A loss of 3.2%-23.2% has been shown in various studies since 1967. It is well known that during cataract surgery many different factors can generate endothelial damages, these include the impact of the nuclear fragments, the turbulence generated in anterior chamber and the volume of liquid. It is also related to the amount of ultrasonic energy used and the subsequent temperature rise, the contact with surgical instruments and the IOL during implantation. It also depends on the release of free radicals the length and features of incision,the surgical technique used . The risk of endothelial cell density loss is further enhanced when surgeons have to deal with high density cataract, shallow anterior chamber and old age.

Since the time Kelman introduced his technique of phacoemulsification, there has been constant and conscious effort on the part of phaco surgeons to reduce their phaco time by bringing some alteration or innovation in their personal technique or introducing new technologies for the procedure of phacoemulsification. Development of Laser emulsifier, SONAAR machines, introduction of cold phaco with modulations of ultrasound in the form of pulse, micropulse and bursts were achievements towards attaining this end and goal.

Coaxial microphacoemulsification is the standard phacoemulsification technique being practised globally for cataract extraction and on many occasions we intentionally do not use the phaco power either at all or fully as per the pre set limit. In fact the use of efficient fluidic controls and a chopper minimizes the use of phaco energy. If we could assess a zero/minimal ultrasound technique in a scientific setting we might achieve the desired goal without resorting to major modifications of instrumentation and machine. Coaxial MICS fully utilizes the advantages of small incision and provides the most comfortable platform for the surgeons using conventional phacoemulsification.

We imagined that most ideal setting would be introducing zero phaco power in the anterior chamber for emulsifying the nucleus as has been done already in case of Aqualase using warm fluid based system and Howard Fines new technique of mechanically emulsifying the lens with rotators(under investigation). For that we undertook a pilot study in 10 patients and performed coaxial microincision phacoemulsification, introducing the ultrasound power in incremental fashion during the surgery in each of the 10 patients till we could achieve the adequate aspiration of fluid and fragments .

At zero power the phacotip and tubing experienced repeated blockages with associated prolongation of surgical time,thus increment to one percent was made during the same sitting. To our surprise, the very first step of introducing 1% ultrasound power made all the difference.No further increments were required as all techniques of nuclear management and lens aspiration were conveniently possible at this setting.

The procedure of aspiration of fragments was smooth and continuous, it also caused a reduction in the surgical time in comparison to zero power phaco.The cases revealed less corneal endothelial trauma in comparison to conventional phacoemulsification using higher power settings. The most surprising observation was that we could dissemble the nucleus with any known technique of nucleus fragmentation(stop and chop, divide and conquer, phaco-chop) in almost all grades of cataracts .Possibly that high vaccum 300-350 is responsible for this nuclear fragmentation and not only the cavitational effects of ultrasound power.

Keeping all the other parameters uniform we wish to design an RCT to study the effect of eliminating phaco power. With this in view,this study compares the endothelial status in addition to various complications and visual outcome following standard coaxial microincision cataract surgery and coaxial microincision cataract surgery using 1% ultrasound.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 72
• Est. completion date: April 2012
• Est. primary completion date: April 2011
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 40 Years and older

Eligibility

Inclusion Criteria:

1. Patients of >40yrs will be included in the study.

2. Grade 0.1-6.0 (LOCS III grading) of senile cataract.

Exclusion Criteria:

1. Patients with pre-operative endothelial cell density count less than 1500cells/mm2.

2. All eye pathologies that can compromise the visual recovery.

3. Eyes with any kind of corneal dystrophy or corneal scars preventing visualisation of cataract for reliable grading.

4. Raised intraocular pressure (> 21 mmHg).

5. Previous intraocular surgery.

Study Design

Allocation: Randomized, Endpoint Classification: Safety Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Cataract

Intervention

Procedure:
• one percent ultrasound power in CMICS
Co-axial MICS shall be performed in cases allocated to this arm .The ultrasound power shall be kept at one percent during the surgery.A note of effective phacotime,volume of fluid aspirated and any intraoperative complications shall be made.
• 40 percent ultrasound power in CMICS
Co-axial MICS shall be performed in cases allocated to this arm .The ultrasound power shall be kept at 40 percent during the surgery.A note of effective phacotime,volume of fluid aspirated and any intraoperative complications shall be made.

Locations

Country	Name	City	State
India	Dr. R.M.L.Hospital,	New Delhi	Delhi

Sponsors (1)

Lead Sponsor	Collaborator
Dr. Ram Manohar Lohia Hospital

Country where clinical trial is conducted

India, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	change in endothelial cell count from baseline over time	Noncontact specular microscope (EM - 3000; TOMEY: VERSION 2A/OJ) will be used to calculate the endothelial cell density, coefficient of variation of cell size, percentage of hexagonal cells and corneal thickness before surgery and 1day, 1 week, 1, 3, 6, 9 and 12 months visits after surgery. 3 endothelial cell photographs will be taken at each visit and the mean cell count of three photographs will be calculated. Counts will be performed by an observer blinded to which procedure the patient had undergone. Endothelial cell loss will be calculated as a percentage of pre operative cell density	1 day,1week,months 1,3,6,9,12	Yes
Secondary	change in Intraocular pressure from baseline	Intraocular pressure will be measured using applanation tonometer.	1day,1week,months1,3,6,9,12	Yes
Secondary	visual acuity	snellens visual acuity will be converted to Logmar scale and recorded with and without spectacle correction	1 month	No
Secondary	posterior capsular rupture	any incidence of posterior capsular rupture during surgery would be noted	day 0 of surgery	Yes