|Year : 1997 | Volume
| Issue : 4 | Page : 215-219
Visual outcome and complications of residents learning phacoemulsification
R Thomas, S Naveen, A Jacob, A Braganza
Schell Eye Hospital, Christian Medical College, Vellore, India
Schell Eye Hospital, Christian Medical College, Vellore
Source of Support: None, Conflict of Interest: None
The increasing popularity of phacoemulsification in our country raises important training issues. We prospectively analyzed the incidence of complications and visual outcomes in the initial 70 phacoemulsifications (70 patients) performed by the first two residents learning phacoemulsification in our training programme. Both were experienced in standard (manual) extracapsular cataract extraction. Postoperative follow up of 6 weeks or longer was available in 59 eyes. The 11 patients (11 eyes) lost to follow up did not have any intra-operative complications. The overall incidence of vitreous loss was 10%, similar to the frequency of this complication (determined retrospectively) in the first 70 standard extracapsular cataract extractions performed by the same residents. Intraocular lenses (IOL) were successfully implanted in 62 eyes, as planned. One IOL dislocated into the vitreous was successfully repositioned. Other complications encountered included superior corneal edema (3 eyes), iris damage inferiorly (7 eyes) and clinical cystoid macular edema (5 eyes). A best corrected visual acuity of 6/12 or better was obtained in 56 (94.8%) of the 59 eyes available for the six week follow up. In the eyes with vitreous loss, 6 out of 7 had visual acuity better than 6/12. No nuclei were lost into the vitreous. The rate of surgical complications for residents learning phacoemulsification in a supervised manner can be acceptably low.
Keywords: Residents, phacoemulsification, training, learning curve, complications, visual outcome
|How to cite this article:|
Thomas R, Naveen S, Jacob A, Braganza A. Visual outcome and complications of residents learning phacoemulsification. Indian J Ophthalmol 1997;45:215-9
The use of phacoemulsification in our country has become popular over the past several years and sooner or later residency programmes will be offering training in this technique. As a result, important safety related issues of training arise. It is evident from the learning curve of experienced cataract surgeons making the transition, that phacoemulsification is quite unrelated to other techniques of cataract surgery., Previous studies from the west have reported the complications associated with residents learning phacoemulsificiation. We began teaching phacoemulsification in our postgraduate training programme two years ago. The primary purpose of this study was to examine the visual outcome and complications encountered by the first two residents learning phacoemulsification in our institution.
| Materials and Methods|| |
We prospectively analyzed consecutive cases of phacoemulsification with or without intraocualr lens (IOL) implantation performed by two residents at the Schell Eye Hospital (Department of Ophthalmology, Christian Medical College, Vellore) over a period of one year. During this time, the two residents between them performed phacoemulsificaiton in 70 eyes. Resident A performed 36 cases, and Resident B performed 34.
Both had completed a two year diploma course in our institution and were final year Master of Surgery residents when the teaching of phacoemulsification was introduced into the training programme. Each resident's independent prior surgical experience included at least 400 manual extracapsular cataract extractions with IOL implantation and about 100 intracapsular cataract extractions. They were comfortable with mechanized anterior vitrectomy for vitreous loss and had been taught to place the IOL on the remaining capsular bag or suture a PC lens to the scleral sulcus. They had prior experience with scleral tunnel incisions and continuous curvilinear capsulotomies (CCC) as part of their training in manual small incision cataract extractions using the Blumenthal technique. Both had assisted about 25 cases of phacoemulsification performed by consultants and also had the opportunity to do some of the individual steps of phacoemulsification (nucleofractis technique) in these cases. They were familiar with the phacoemulsification machine and foot pedal. The Alcon 9001 model was used for all the cases. All intraoperative complications in this series were managed by the residents themselves.
We selected patients with immature cataracts (Grade II-III nuclear sclerosis) and no ocular complications. Patients with other grades of nuclear sclerosis, subluxated lenses, poorly dilating pupils, uveitis, and central endothelial guttate changes were excluded.
Local anaesthesia comprising a retrobulbar and O'Brien facial nerve block was used in all cases. The anaesthetic agent used was 2% xylocaine with adrenaline to which hyaluronidase was added. Manual compression was used to reduce the intraocular pressure.
The operative procedure has been described earlier and was essentially the same as that described by Cruz et al with modification described by Thomas et al. In all cases, 2% methyl cellulose was used instead of a viscoelastic, the CCC was performed in a closed chamber through the paracentesis, and endocapsular nucleofractis used for emulsification. The initial operations were assisted by an experienced phacoemulsificaiton surgeon; all operations were approached with a mindset of "bailout". If an intact CCC could not be obtained, the procedure was converted to a manual technique. During emulsification, if the supervising surgeon recognized loss of integrity of the zonules or posterior capsule, or a tear in the CCC was detected, a decision was made to "bail out" to a standard ECCE.
Vitreous loss was defined as rupture of the posterior capsule or zonule, along with rupture of the anterior vitreous face, resulting in vitreous appearing anterior to the plane of the posterior capsule. This complication was managed by performing mechanized vitrectomy using the Series 8000 Ocutome (Cooper Vision), attempting to preserve as much anterior and posterior capsule as possible for supporting a PCIOL. All patients with vitreous loss underwent a meticulous mechanized vitrectomy using an endoilluminator to help identify the vitreous and ensure that there was no vitreous incarcerated in the wound or any residual vitreous in the anterior chamber.
The preoperative and postoperative examinations followed a standard protocol. This consisted of a complete ocular examination including applanation tonometry, slitlamp examination before and after dilatation of the pupil, gonioscopy if indicated, dilated binocular indirect ophthalmoscopy and slitlamp fundus biomicroscopy using a 78 D lens. Retinoscopy and subjective acceptance of spectacle corrections were performed by an experienced optometrist. An independent ophthalmologist recorded all the operative findings and examined the patients post operatively. The diagnosis of clinical cystoid macular edema (CME) was made by a retinal surgeon on the basis of decreased vision and biomicroscopy of the macula.
In order to compare the vitreous loss rates during the teaching of manual extracapsular surgery versus phacoemulsification, we retrospectively analyzed the frequency of vitreous loss in the first 70 manual extracapsular lens extractions (in the same ratio as for phacoemulsification) preformed by the same residents during the first year of their diploma training.
| Results|| |
| Follow-up|| |
In a one year period, phacoemulsification with and without IOL implantation was performed by the two residents on 70 eyes of 70 patients. The final results were evaluated at 6 weeks post-operatively. 11 patients were lost to follow up after the first week (Resident A: 4 eyes; Resident B: 7 eyes). All had best corrected visual acuity of 6/12 or better postoperatively when last examined. These 11 eyes were not included in the final visual outcome analysis. As pre-operative and intra-operative data were available for these 11 eyes they were included in the assessment of the intra-operative complications.
| Intraoperative complications|| |
In 4 of the 70 eyes, we "bailed out" of phacoemulsification and converted to a standard extracapsular cataract extraction. In three of these, the reason for "bailing out" was the absence of an intact CCC. In another eye the resident had difficulty in emulsifying a soft nucleus and preferred to convert to the Blumenthal manual small incision technique. Vitreous loss occurred in 7 eyes (10%); 5 during phacoemulsification (3 with zonular dialysis), 1 during cortical aspiration and 1 during insertion of intraocular lens. Five of the 7 vitreous losses occurred in the first 15 cases done by each resident. One case had minimal cortical matter in the vitreous which did not require intervention. Loss of a portion of or the entire nucleus did not occur in any eye. The number of cases performed and complications encountered by each resident are listed in [Table;1] and [Table - 2].
| IOL implantation|| |
IOLs were planned for 62 eyes and were implanted in all of them. The remaining 8 cases had aphakic fellow eyes. Two eyes with vitreous loss required scleral fixation of the superior haptic. The inferior haptic was placed on the anterior capsular remnants. In one of the cases the intraocular lens was displaced into the vitreous. This was noticed postoperatively and managed by a vitreoretinal surgeon with vitrectomy and repositioning of the IOL with scleral refixation.
| Postoperative complications|| |
The postoperative complications encountered are listed in [Table - 2]. Three cases had localized persistent corneal oedema away from the wound area. Two of these had best corrected visual acuity of 6 / 6 and one patient had associated cystoid macular edema (CME) with a visual acuity of 6/12. An "in the bag" hyphaema was noticed on the first postoperative day in one eye; this resolved with conservative management. Phacoemulsification probe induced iris damage was seen interiorly in seven eyes. This did not cause any cosmetic problem. Clinical CME developed in 5 patients and was the primary cause for visual acuity less than 6/12.
| Visual acuity|| |
Fifty-nine of 70 eyes were seen at 6 weeks post-operatively; 43 achieved a corrected visual acuity of 6/ 6. Fifty-six eyes of 59 (94.8%) had visual acuity of 6/12 or better. Of the three eyes with vision less than 6/12, one achieved 6/18, another 6/24, and the third 6/60. All these three eyes had CME; the eye with 6/60 vision also had posterior capsular opacification. Six of the 7 eyes with vitreous loss achieved a vision of 6/12 or better. The results of resident cataract surgery reported in the literature is compared to our experience in [Table - 3].
| Discussion|| |
The current popularity of phacoemulsification raises the issue of the morbidity involved in learning this technique. In our country, to the best of our knowledge, training in phacoemulsification is not available in most residency programmes. The technique of phacoemulsification is routinely taught in most Western residency programmes and the experience has been reported. We found that the supervised phacoemulsificaiton learning curve for residents experienced in manual extracapsular cataract extractions (and the management of related complications) to be acceptably low.
Clinically detectable CME was found in 5 eyes of which 2 had vitreous loss. The other complications like iris trauma by the phacoemulsification probe, in the bag hyphaema and mild localized corneal oedema away from visual axis due to endothelial touch with the probe were considered minor and did not interfere with visual outcome.
The rate of vitreous loss was 10%, slightly less than the rate reported by Allinson et al (14.7%), and Cotlier & Rose (14.2), but higher than that reported in by Cruz et al (5.5%) in their retrospective study. The differences in rates are small enough to lie within 95% confidence limits. As in the previous reports, the majority of vitreous losses occurred in the initial part of the training. Notwithstanding vitreous loss, the postoperative visual acuity in these cases were good, similar to those cited in previous reports.
The vitreous loss rate for the same residents learning manual extracapsular cases (in the first 70) was similar (8.6%). A best corrected visual acuity of 6/12 or better was obtained in 59 of 70 eyes or 84%; (Resident A 29/36 and Resident B 30/34). The number of cases with acuity 6/12 or better was lower for the standard extracapsular series compared to the phacoemulsification series (94.8%). This could be because an IOL was not implanted in most of the eyes undergoing standard extracapsular surgery. Perhaps the surgical experience gained before learning phacoemulsification too played a role.
IOLs could be inserted in all of the cases for which they had been planned; this reflects the residents surgical experience. Two eyes required scleral fixation of one haptic of a posterior chamber lens. One IOL dislocated into the vitreous and was successfully repositioned postoperatively by the vitreoretinal surgeon and required refixation to the sclera.
Loss of the nucleus (or a fragment) into the vitreous did not occur in any case. Considering the confidence interval, the absence of this complication in 70 eyes is still compatible with a true nucleus loss rate of 4%. The rate of this complication for the senior author making a supervised transition to phacoemulsification was one of 51 eyes. The current overall rate of nucleus loss in our hospital is 1% (data to be published). We feel that the absence of this complication in the current series is related to our training philosophy. All cases were approached with a mindset of "bailing out" into standard extracapsular surgery at the slightest hint of a complication that could lead to a dropped nucleus. If the CCC was not intact, we did not feel it was safe for any inexperienced resident to proceed with phacoemulsification. While we did not insist on the "Thomas frisbee manoeuvre", we did ensure that the nucleus was relatively free in the capsular bag before proceeding with phacoemulsification. If the nucleus did not rotate easily, the hydrodissection was repeated to make this easier.
Currently in our training programme, residents begin learning phacoemulsification by the 2nd year of their Masters course. By that time each resident usually has experience with 250 plus extracapsular cataract surgery with IOL implantation performed independently and a variable number of intracapsular cataract operations. This includes independent management of complications involving vitrectomy and scleral fixation of IOL. Each resident has also performed several scleral pocket incisions and CCCs as part of their training in the Blumenthal technique of manual small incision surgery as well as with standard ECCE before attempting phacoemulsification.
We feel the complication rate would have been higher if the residents did not have expertise in standard (manual) extracapsular surgery, scleral tunnel incisions, and the CCC technique. While experience equivalent to our residents is a not a prerequisite for learning phacoemulsification, we believe that confidence with extracapsular surgical techniques as well as the preliminary steps required for safe phacoemulsificaiton were responsible for the acceptable visual outcome and low complication rates. As we gain experience with training, phacoemulsification has been introduced earlier in the masters course. However, we do not share the view that phacoemulsification can be safely preformed without prior experience in standard extracapsular cataract surgery. This is especially true for independent phacoemulsification. Should a problem be encountered, a standard extracapsular extraction is the technique the surgeon has to convert to. If a complication requiring abandoning of phacoemulsification were to occur, a surgeon without experience in standard extracapsular surgery would be converting to an equally unfamiliar technique. To use an analogy, this is like "bailing out" into tiger country and could prove to be detrimental to the final outcome. In fact, some experience (hopefully limited) with the use of a vectis as used in intracapsular surgery (a technique with which most ophthalmologists in this country are familiar), is comforting in the scenario of a nucleus about to sink into the vitreous.
More recently, we use an anterior chamber maintainer (Visitec, catalogue number 5061 or 5163) routinely for training purposes. The constant infusion independent of the phacoemulsification handpiece makes chamber maintenance easier, prevents shallowing of the chamber, helps in obtaining complete hydrodissection, and aids rotation of the nucleus. Also, the anterior chamber is kept fully formed as cortex is safely aspirated through the paracentesis incisions. As some vitreous losses occur during cortex aspiration, the maintainer could help decrease the rate of this complication. The infusion from the anterior chamber maintainer (with a lowered bottle height) is also of help in teaching (or performing) anterior vitrectomy in the event of a vitreous loss. We used an older model of phacoemulsifier with fixed settings and low cutting power. Perhaps the use of a modern machine may improve results further.
We have presented our experience with the training of residents in phacoemulsification. In our hands, the planned, supervised phacoemulsification training of residents experienced in standard extracapsular surgery does not have a morbidity that should raise undue concern.
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[Table - 1], [Table - 2], [Table - 3]