|Year : 1983 | Volume
| Issue : 5 | Page : 558-562
Pars plana lensectomy using ultrasonic fragmentation
Mary Nalini Abraham, Manju Kulkarni, SS Badrinath
Sankara Nethralaya, Medical Research Foundation, 18 College Road, Madras, India
Mary Nalini Abraham
Sankara Nethralaya, Medical Research Foundation, 18, College Road, Madras-6
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Abraham MN, Kulkarni M, Badrinath S S. Pars plana lensectomy using ultrasonic fragmentation. Indian J Ophthalmol 1983;31:558-62
This paper deals with the study of 42 eyes of 35 patients in whom pars plana lensectomy was performed using the ultrasonic fragmentor. This was done at Sankara Nethralaya, Madras between June 1979 and May 1981. The procedure, the complication encoutered and the results obtained will be discussed.
| Materials and Methods|| |
The Berkley Bio Engineering Ocutome Fragmatome system was used in all the cases. In 7 cases the procedure was done bilaterally 28 of the patients were males and 7 females. The youngest was one month old and the oldest 65 years of age. Congenital, complicated and traumatic cataracts were the most common indication for lensectomy occurring in the 1-10 years age group and lens frequently was subluxated lens, senile cataracts and where it was done prior to vitrectomy to aid visualization [Table - 1],[Table - 2]. The planned lensectomy was done in 32 eyes while in 8 others, it was combined with vitrectomy or scleral buckling procedures [Table - 3]. In 2 eyes the lensectomy was done as a preliminary procedure to aid visualisation of the interior of the eye.
A preliminary ultrasonography was done in 19 eyes where there was no view of the fundus, in order to assess the state of the retina and its adjacent structures. [Table - 4]
The fragmatome was used in all cases for the removal of the nucleus and cortex whereas the posterior capsule was removed with the ocutome. A good anterior vitrectomy was also performed in all the cases with the ocutome.
Of the 42 eyes studied, 36 had less than 6 months follow up but more than 2 months and 6 eyes have been followed up for more than 6 months.
An hour and a half before surgery, the patients' pupil was maximally dilated with 10% phenyl ephrine and 2% homatropine. The drops were instilled every 10 minutes for 10 times.
The surgery was performed either under local or general anaesthesia. It was unnecessary to use digital massage, aqueous inhibitors or osmotic agents to lower the intraocular pressure, as the pressure can be controlled by the surgeon during the procedure.
The patients' eyes were prepared in the usual manner with particular care taken not to get disinfectants or soaps in the eyes. The draping was done in the usual manner including a sterile plastic drape over the eye. The lids were held apart either with a speculum or lid sutures and the cornea kept moist with saline.
A canthotomy was performed in those cases where the palpebral aperture was inadequate for the manipulation of the instruments.
The conjunctiva was grapsed at the limbus at 6 o'clock and the eye rotated down by the assistant. The sclera was exposed in the superior nasal and superior temporal quadrants by conjunctiva incisions about 4-5 mm. from the limbus and parallel to it. The pars plana was then located by means of calipers at a point 3.5-4 mm. from the limbus and the site marked by light cautery. A myringotomy knife of 20 mm. diameter was used to make the sclerotomy. The first sclerotomy, was done at 10 o'clock position. The knife was carried through the equator into the centre of the lens, where it was well visualized through the dilated pupil. The knife was then swerved from side to side in order to macerate the nucleus and also to test the hardness of the nucleus.
The myringotomy knife was slowly withdrawn taking care to release all pressure on the eyeball and therefore prevent the escape of vitreous through the wound. This was followed by the introduction of the stilleto in the direction of the mid vitreous cavity which helped in making the sclerotomy more rounded. The sclerotomy was then plugged with a scleral plug also of 20 mm.; diameter making the eyeball water tight.
A similar procedure was repeated at the 2 o'clock position. Having made the sclerotomies, the fragmentor and irrigation systems were checked and introduced into the 10 o'clock and 2 o'clock openings respectively. The tips of the instruments were visualized througout the procedure.
A power setting of 6 W was found sufficient in almost all the cases. When the two instruments where inside the globe, it was possible to control the position of the globe using the scleral incisions as points of fixation.
When all the parameters were found satisfactory, the irrigation was started followed by short bursts of ultrasonic fragmentation interspersed with pure aspiration. The piezo-electric crystal in the fragmentor when activated causes it to vibrate at 35,000-40,000 cycles/sec. which are transmitted by resonance to the tip which in turn vibrates longitudinally 0.09 mm. It is this physical movement called the `hammering effect' that is mainly responsible for the fragmentation of the lens. The secondary effects are cavitation and microsteaming which are produced at the tip.
The entire nucleus was first fragmented and aspirated which was followed by the removal of the anterior and posterior capsules. The fragmentor was then slowly removed and replaced by the ocutome which removed all remnants of the posterior capsule and a good anterior vitrectomy was done at the end of it.
The entire procedure was done under microscopic visualization using co-axial illumination. A good red fundal glow and a clear pupillary area marked the end of the procedure. Care was taken during the entire procedure to avoid unnecessary sphincterotomies, loss of lens fragments and damage to the corneal endothelium.
The scleral openings were then plugged after removal of the instruments and the retina examined thoroughly by indirect ophthalmoscopy for the presence of lens droppings, or retinal tears. The incisions were then inspected for prolapsed vitreous which if present was cut. The sclerotomies were closed with appropriate mattress sutures ensuring that the eye was water tight. The conjunctiva was closed with a continuous suture of the same material.
| Results|| |
The shortest time taken was 6 seconds and the longest 6 minutes. Soft cataracts were found to clear very rapidly whereas hard lenses and complicated cataracts tended to take more time.
The most frequent complication met with operatively was the occurance of lens droppings into the vitreous cavity as seen in 6 eyes (14.3%) and this was due to the preliminary rupture of the posterior lens capsule [Table - 5].
Every attempt was made to aspirate and retrieve the lens fragments, but small was left alone as it absorbed in the course of time. This was however considerably less when compared to our previous technique using the Wilsons Fragmentor where lens droppings was in the range of 34%.
By running the infusion behind the lens rather than within it, the chances of lens fragments dropping back were considerably reduced as the flow of saline acted as a barrier keeping the lens fragments floating in the anterior chamber.
In 6 eyes fragmentation of the lens was difficult owing to their hardness and faulty power setting (this being our initial patients done in 1979).
Mechanical difficulty in manoevering the instruments was seen in 2 eyes where there were microphthalmic and the palpebral aperture narrow. In all these cases, a canthotomy was done and the head turned to one side in order to allow sufficient space for the introduction and manipulation of instruments.
Vitreous loss at the wound was seen in 4 eyes, which was cut with the ocutome until saline escaped freely from the wound.
The incidence of vitreous prolapse at the wound was greatly reduced by lowering the intraocular pressure, (by lowering the height of the infusion bottle) before the removal of the instruments. The nucleus subluxated into the anterior chamber in one case and posteriorly in another, which was removed after a good anterior vitrectomy, using the saline to float up the lens anteriorly from where it was fragmented and aspirated. In one case where the subluxated lens was very hard, the Arrugas forceps had to be used after a small corneoscleral section to deliver it.
In eyes with traumatic and complicated cataract when there were dense synechiae between the lens and iris, sphincterotomies were inevitable and aided in clearing as much of the lens as possible.
Extreme pupillary miosis occurred in 4 eyes during the procedure which were overcome in all except two with lml of 1:5000 adrenaline injected intracamerally. In two eyes however, it was not possible resulting in accidental sphinterotomies.
An accidental rupture of the retinal blood vessels leading to profuse intraocular bleeding occured in 2 eyes of combined lensectomy and vitrectomy and the procedure had to be abandoned.
Closure of the sclerotomy was done with 6/0 nylon in 33 eyes and 8/0 nylon in 8 eyes, both of which were tolerated very well, producing minimal tissue reaction, but necessitated removal of the conjunctival sutures at the end of 1 week. 4/0 mersilene was used in one eye which remained irritable in the initial postoperatively period.
The post-operative period was generally very quiet, the eye being white and comfortable even from the first post-operative day..Iridocyclitis was seen only in 7 eyes which cleaned with atropine and steroids. Corneal striate keratitis and epithelial oedema were seen in 2 eyes each, both of which were transient, occurred in the first post operative week and were probably a result of mild damage to the corneal endothelium by either the instruments or saline. Transient glaucoma was seen in 2 eyes which was controlled with Diamox. In 2 eyes a secondary glaucoma ensured which necessitated a peripheral iridectomy and anterior synecheolysis in one and a cyclocryotherapy in the other where the glaucoma was neovascular. After cataracts were seen in 5 eyes, in which only 2 required a membranectomy. Metallic shavings were seen on the posterior capsule in one case. [Table - 6].
35 eyes of the 42 eyes obtained a good clearing of the pupillary area enabling a good view of the fundus and periphery. [Table - 7]
In 5 eyes with capsular remnants, only two required a membranectomy as the visual acuity was considerably reduced. Dense hyphema due to intraocular bleeding was seen in 2 eyes making it difficult to assess the clearing obtained.
[Table - 8] shows the visual recovery. [Table - 9] summarises the causes of poor vision (less than 6/18).
| Discussion|| |
Pars plana lensectomy using ultrasonic fragmentation is a large step in the progressive development of cataract surgery, using an extremely small scleral incision and a closed system to maintain intraocular pressure during the surgery.
Pars plana lensectomy, does not disturb the cornea, leaving the eye quiet in the post operative period and allows early ambulation and maximal patient comfort. Though this procedure requires considerable skill with the ultrasonic fragmentor and operating microscope, bimanual dexterity and experience with surgery of the posterior pole of the eye, it has a definite role in the management of congenital, complicated or traumatic cataracts and in these cases where a vitreous loss is inevitable with conventional techniques. If the vitreous is disturbed an anterior vitrectomy can be easily performed with the same instrument. The fragmentor also allows related procedures to be performed at the same sitting for example, vitrectomy or scleral buckling procedures.
| Summary|| |
In this series we have studied 42 eyes that underwent pars plana lensectomy using ultrasonic fragmentation. The fragmentor could be used with ease in various age groups and was found ideal for the management of soft and intermediate hard cataracts. The system could also be used to perform a simultaneous vitrectomy in addition.
The operative and post-operative complications were minimal, most of which were reduced by the techniques mentioned.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8], [Table - 9]