Abstract】 Objective To investigate the effectiveness of the modified intercept-and-cleave technique in the application of ultrasonic emulsification of hard cataracts. Methods A modified intercept-and-split technique was performed in 54 eyes with cataracts of grade III or higher nuclear hardness, in which an emulsion needle was embedded in the nucleus to a depth of 1/2 to 3/4 of the nuclear thickness after carving a bowl in the center of the nucleus, using negative pressure.
The nucleus is fixed, and a splitter is used to enter the nucleus via the 3 o’clock equatorial part of the nucleus, so that the head of the splitter corresponds to the emulsifying head. The average time of ultrasonic emulsification was 1.7 min, together with the continuous circular tearing capsule under the anterior chamber filled with viscoelastic and the water separation technique. The intraoperative ultrasound time and effective ultrasound time were shorter in the modified interception-cleavage group than in the interception-2-cleavage group, and the difference was statistically significant (P<0.05). The main complications were posterior capsule rupture in 12 eyes, corneal edema in 33 eyes, and posterior cataract in 3 eyes. Conclusion The modified interception-cleavage technique is one of the effective nucleus fragmentation methods in sclerocystic cataract ultrasound emulsification, with short ultrasound time, few complications, and easier and safer nucleus fragmentation. Keywords: cataract; nucleus splitting; ultrasound emulsification How to reduce the ultrasound energy, shorten the operation time and reduce the complications during cataract ultrasound emulsification aspiration has been of great concern to the surgeons. Currently, most of our cataract attendants have nuclear hardness of grade III [1], so ultrasound emulsion surgery for hard nucleated cataracts has received even more attention. In this study, we achieved good results in ultrasonic cataract aspiration for hard nucleated (grade III and IV nuclei) cataracts using a modified interception-cleavage technique. It is reported as follows. 1 Materials and methods: 1.1 General data: 89 patients (98 eyes), including 41 males (43 eyes) and 48 females (56 eyes), aged from 48 to 88 years old, with an average of 70.1 years old, underwent ultrasonic cataract aspiration in our hospital from September 2004 to January 2006 with complete data. There were 82 eyes with senile cataracts and 16 eyes with combined high myopia cataracts. Preoperative lens nucleus grading: 85 eyes with grade III nucleus and 14 eyes with grade IV nucleus. The preoperative visual acuity was photopic ~0.15, and all cases were randomly divided into two groups: 54 eyes in the modified interception-cleavage group (referred to as modified group) and 45 eyes in the interception-cleavage group (referred to as interception group). The age and composition ratio of different hardness lens nuclei were comparable between the two groups. 1.2, surgical method: posterior ball anesthesia was used, scleral tunnel incision was used at the initial stage, and clear corneal incision was used at the later stage. In the modified group, the energy was set at 55% (linear), the flow rate was 21 ml/min, and the negative pressure was adjusted to 150 mmHg during the sulcular tunneling and 150-200 mmHg during the nucleus splitting and emulsification. At the same time, an auxiliary hook was inserted from 3 points under the anterior capsule and slid to the periphery. When it was close to the equator, the direction was changed to the center of the nucleus and touched with the emulsifying head, and after both were clamped, the nucleus was squeezed and split into two halves, and this operation was repeated after the nucleus was rotated. The interception-cleavage group was performed according to the method of Yao K [2]. The parameters of ultrasonic emulsification were the same as those of the modified group. i/A removal of residual cortex. A 5.5-mm diameter posterior chamber IOL was implanted in the capsular bag, and the incision was not sutured, and all procedures were performed by the authors. Ultrasound energy, negative pressure, ultrasound time (US) and effective ultrasound time (EP) were recorded intraoperatively. Intraoperative and postoperative complications and corrected visual acuity at 3, 7 and 30 days postoperatively were also observed. 1.3. Statistical methods: Intraoperative ultrasound time and effective ultrasound time in both groups were recorded in the form of t-test with α=0.05 as the test level. 2 Results: 2.1 The mean intraoperative ultrasound time was (3.28±1.25) min in the modified group and (3.55±1.35) min in the intercepted group. the difference between the two groups was statistically significant (P<0.05). The mean effective intraoperative ultrasound time was (1.02±0.59) min in the modified group and (1.37±0.54) min in the intercepted group, and the difference between the two groups was statistically significant (P<0.01). The number of eyes with visual acuity ≤0.4 at 3, 7 and 30 days after surgery were 33, 14 and 7 eyes in the improved group, and 36, 22 and 8 eyes in the interceptor group; the number of eyes with visual acuity between 0.5 and 0.9 were 16, 28 and 27 eyes in the improved group, and 8, 18 and 24 eyes in the interceptor group; the number of eyes with visual acuity ≥1.0 were 5, 12 and 20 eyes in the improved group, and 1, 5 and 12 eyes in the interceptor group. 2.2 Complications Intraoperative rupture of the posterior capsule and vitreous detachment: 12 eyes in the modified group and 15 eyes in the intercepted group. After anterior segment vitrectomy and first-stage ciliary sulcus implantation of posterior chamber IOL, 33 eyes (61.11%) in the modified group and 38 eyes (84.44%) in the intercepted group had postoperative corneal edema; the general recovery was 1 week after surgery and the longest recovery was 4 weeks after surgery, with no corneal loss. Atrial clouding: 9 eyes (16.67%) in the modified group and 7 eyes (15.56%) in the interrupted cleft group. 3 DISCUSSION: Ultrasonic emulsion surgery for sclerotic cataract has large relative energy complex parameters [3], high surgical difficulty and complications compared to class II and III nuclei.Nagahara [4] was the first to propose the emulsion cleavage method. This method involves burying the ultrasound needle into the center of the nucleus to fix the nucleus, and then using a splitting hook to forcefully split the lens nucleus into several pieces from the equator toward the center and emulsify and aspirate them piece by piece. Koch [5] proposed the stop and chop technique, in which a hook is carved into a groove, the nucleus is split in half, and the nucleus is cleaved and then emulsified piece by piece. The biggest advantage of the chopping technique is to reduce the ultrasonic time by mechanically splitting the nucleus. In the author’s experience, it is very difficult to make a longitudinal groove for hard nucleus cataract, but also use more energy and longer time. In the present modified technique, instead of grooving the central part of the nucleus before cleavage, the bowl is first grooved as in the case of whole nucleus cleavage [1]. The front end of the cleaver is curved at a right angle, with a rounded tip and no side edges. Instead of entering the nucleus through the equatorial part of the nucleus at the 6 o’clock position, the cleavers enter the nucleus through the equatorial part of the nucleus at 3 o’clock. The difference in ultrasonic emulsification time between the modified and intercepted groups was significant (P<0.05), and the difference in effective ultrasonic emulsification time between the two groups was highly significant (P<0.01). The effect of intraoperative ultrasound on the ocular tissue depends mainly on two parameters, energy and time, in addition to the distance of the ultrasound source from the ocular tissue. The ultrasound emulsifier used in this group of cases recorded the effective ultrasound time (ultrasound time when 100% energy was used) at the same time, in addition to the usual ultrasound time. This parameter, which takes into account both ultrasound energy and ultrasound time, is an ideal parameter for a comprehensive and accurate expression of ultrasound efficacy. In this study, the mean ultrasound time and mean effective ultrasound time of the modified group were reduced by 11.5% and 37.4%, respectively, compared with the intercepted group. The reduction of effective ultrasound time was more obvious. The postoperative corneal edema was also less in the modified group than in the intercept group due to the shortened ultrasound time, which is consistent with what has been reported in the literature [3]. Another feature of this modified technique is that it reduces the number of rotations of the crystal within the capsular bag, thus causing less damage to the suspensory ligament, especially in those with cortical liquefaction, which is not easily grooved and is well suited for this method. (2) Fixation of the lens nucleus: good fixation of the lens nucleus is a prerequisite for mechanical nucleus splitting. The ultrasound needle must be inserted into the center of the lens nucleus, causing a full blockage state. If necessary, the full blockage of the ultrasound needle can be achieved with the help of the splitting hook through the synergy of both hands, and when the peak negative pressure is reached, the lens nucleus is firmly fixed on the emulsion needle. (3) The cleavage hook should avoid damage to the anterior capsule membrane and suspensory ligament when splitting the nucleus: insert the cleavage hook from near the central part (to be away from the edge of the torn capsule opening), slide along the nuclear surface under the anterior capsule to the equatorial part and enter under the nucleus, and the cleavage hook is correctly positioned before splitting the nucleus. To prevent accidental injury to the cystic membrane, the head end of the cleavage hook should be inserted as far as possible in the soft cortex around the nucleus. Intraoperatively, if the nucleus is found to be deviated, the anterior chamber is deepened. If the nucleus is difficult to rotate or the fragmented nucleus does not follow the attraction of the emulsifying head, we should be highly alert to the presence of cystic membrane defect or injury to the suspensory ligament. The nucleus should be extracted by decisively enlarging the incision. Modified interception-splitting technique has the features of short ultrasound time, less complications, easier and safer nucleus splitting. It is a more ideal procedure for the treatment of sclerocystic cataract.