IJCRR

IJCRR - 4(23), December, 2012

Pages: 104-110

Date of Publication: 15-Dec-2012

VISUAL OUTCOME AFTER MICROCOAXIAL PHACOEMULSIFICATION WITH MICRIOL PLUS LENS IMPLANTATION

Author: Mohd Dilawar Mir, Tufela Shafi, Manzoor Qadir Keng, Asifa Jehan, Tasneem Muzaffar, Raashid MaqboolWani

Category: Healthcare

Abstract:Background: Study carried out in a tertiary care eye institute in North India with the aim of evaluating the visual outcome after Microcoaxial Phacoemulsification with MICRIOL PLUS lens implantation as well as to study the intraoperative and postoperative complications associated with the procedure. Methods: Prospective study conducted in one hundred cases over a period of one year. Patients with grade 1 to 3 nuclear and corticonuclear cataracts were included in the study after undergoing complete ophthalmic evaluation. Each patient underwent Microcoaxial Phacoemulsification using incision size of 2.2 mm and MICRIOL PLUS lens was implanted in each case using 'D' cartridge. Patients were followed up for a period of 6 months and visual acuity, slit lamp biomicroscopy, IOL centration, capsule opacification were noted during follow up. Results: Microcoaxial Phacoemulsification was successfully performed in all 100 eyes. 93 % patients achieved a BCVA of 6/9 or better over a 6 month followup, the procedure being associated with low intraoperative and postoperative complications. Conclusions: Microcoaxial Phacoemulsification with MICRIOL PLUS lens is a safe and cost effective alternative surgical procedure for management of cataracts with excellent postoperative visual acuity and few intraoperative and postoperative complications.

Keywords: Cataract, Visual Outcome, Microcoaxial Phacoemulsification, Bimanual Phacoemulsification, MICRIOL PLUS lens, D cartridge.

Full Text:

INTRODUCTION
Cataract surgery has undergone remarkable technical refinement, with simplified postoperative care and faster visual recovery as consequences.1,2 . With improved instrumentation, small incision Phacoemulsification became possible in the late 1980s, leading to the current state of the art of sutureless phacoemulsification surgery with foldable intraocular lens implantation3,4 . Phacoemulsification introduced by Dr. Charles Kelman in 1967, utilizes a small incision. The incision size for routine phacoemulsification is approximately 3 to 3.5mm in width. This small 3.5 mm incision required for standard phacoemulsification is self sealing and generally does not require any suturing, as it is watertight. The smaller the incision, the less the pressure changes, the more stable the anterior chamber, the more the control during capsulorrhexis and hydrodissection. Smaller wounds heal more rapidly, with less risk of leakage and endophthalmitis. Besides, the surgically induced astigmatism is also much less with a smaller incision. However at present, the incision size is limited not only by the diameter of the phacoemulsification tip but also by the irrigation sleeve around the phacotip, which provides irrigation fluid into the anterior chamber besides adequate fluid to cool the phacoemulsification needle5 . If a rigid intraocular lens implant is used, the incision has to be enlarged upto 5.0mm to 5.5mm. If the lens implant that can be folded is used, this may not have to be enlarged. With the introduction of microincisional cataract surgery, phacoemulsification can be done through incisions of 2.2 mm or less, using either the Bimanual or Microcoaxial technique. Surgeons who perform bimanual phacoemulsification, create two 1.5mm to 1.2 mm incisions, one to insert an irrigation hand piece and the other to introduce a sleeveless phaco tip to remove the cataract. Apart from the various advantages of a small incision, microincisions further reduce surgically induced astigmatism. However, smaller incisions come with their own problems. Generally sleeveless phacotips need to be used through these incisions,with fluid inflow into the anterior chamber being maintained separately through the irrigation handpiece . The low flow rates from the small irrigating tips placed through these incisions may compromise anterior chamber stability. Besides once the inflow into the anterior chamber is reduced, the aspiration rate also gets limited6 . In such a situation, high vacuum levels and post occlusion surge potentially can threaten the safety of the procedure. In addition, the sleeveless phaco tips can overheat, thereby raising the risk of thermal damage to the cornea. Microcoaxial Phacoemulsification Microcoaxial phacoemulsification also known as coaxial micro-incision cataract surgery (C-MICS) requires an incision less than or equal to 2.2mm and accommodates a sleeve over the phacotip. Therefore aspiration and irrigation can be carried through the same incision and implantation of a foldable IOL can be done without enlarging the incision3 . The instrument and surgical technique is the same, only the incision size is variable. The machine parameters need to be reset and higher vacuum (400-450 vaccum) needs to be used and the surgeon needs to get used to the more controlled procedure7 . For C-MICS a microincision sleeve, micro-coaxial phaco needle, an appropriate keratome and micro-coaxial irrigation / aspiration are needed. A standard sleeve has a 1.8mm diameter, whereas a coaxial sleeve has a smaller diameter of 1.6mm which tapers to 1mm at the tip8. With bimanual micro phacoemulsification, unsleeved rigid round tips are used which induce distortion of the small slit incisions and at times result in the fish mouthing of these incisions. In contrast, the sleeve around the phacotip in CMICS acts as a buffer and does not distort or ‘fish mouth’ the incision. These microincisions are snug fitting, self seal and do not leak post or intraoperatively. There is at times poor chamber control with bimanual microphacoemusification due to imbalance between aspiration and irrigation flow, particularly if aspiration is continued when there are no nuclear particles which need to be captured by the aspiration port 9 ; however, with the coaxial microphacoemulsification, the fluidics are basically the same as those seen with standard phaco. Surge testing has also demonstrated that there is less surge and greater chamber stability during coaxial microphacoemulsification using the thin sleeve than during the bare tip bimanual technique10 . The attractive feature of coaxial microphaco is that the phaco tip is covered with a sleeve and yet it is sub 2mm, therefore all the above mentioned disadvantages of bimanual microphaco are obviated. Standard technique of coaxial phaco is used and no extra instrumentation or steep learning curve is required. The whole procedure can be performed through sub 2mm wound size and the IOL can be introduced through the same using wound assisted insertion without the need to enlarge the wound. However, there is a limited availability of the small size IOLS which can be implanted through these microincisions and most of them are quite expensive, limiting the population in which this procedure can be carried out. Cost factor plays a major role in deciding the type of lens and hence the type of surgery which can be carried out in the majority of the patient groups from developing countries like ours. MICRIOL PLUS lens from Care Group meets all the needs of the lenses required for microincisions besides being low in cost, hence we selected this for our study with the view of popularizing this surgical procedure to all sections of the society particularly to the patients from low socioeconomic strata.

RESEARCH METHODOLOGY
Patients in the age group between 10 years to 70 years, having Grade 1 to 3 nuclear and corticonuclear cataracts (LOCS-III classification system), a transparent central cornea, pupil dilatation at the preoperative examination of at least 6 mm, absence of Bio-microscopical signs of pseudoexfoliation and with no active fundus pathology were included in the study. Patients with high density lens opacity (LOCS-III : NO5- NO6, C4-C5, P4-P5), relevant corneal opacities, Pseudoexfoliation syndrome, pupil anomalies, synechia, zonulolysis or defective zonules, abnormal fundus, history of ocular trauma, intra ocular surgery as well as history of serious coexistent ocular diseases such as uveitis, glaucoma, optic atrophy or ocular tumors, Diabetes Mellitus or other metabolic diseases were excluded from the study. Only 100 patients who fulfilled the criteria and completed the followup schedule were included in the study. Preoperative assessment included Visual acuity, complete slitlamp and fundus examination, keratometry and A- Scan.

Procedure and Instrumentation (Fig 1&2)
Microcoaxial phacoemulsification.
In all patients, maximum mydriasis was achieved with 1 drop each of a combination of tropicamide (0.8%) and phenylephrine (5%) and cyclopentolate (1%) applied 4 times 1 hour before surgery. Peribulbar block was used to achieve anesthesia and akinesia. All the cases were operated upon by a single surgeon. Following disinfection and draping, a clear corneal stab incision was created at 12 O’clock position using a 2.0 mm keratome. Two side port stab incisions (1mm) were made at 10 O’clock and 2 O’clock position. An air bubble was then injected through the side port, followed by application of 0.1 to 0.2ml of trypan blue solution over the anterior capsule for capsular staining. After 20 seconds, the trypan blue solution was aspirated. The anterior chamber was then filled with viscoelastic fluid. Continuous curvilinear capsulorhexis was then performed with a bent 26 gauge disposable needle mounted on a syringe. In case of difficulty in completing the CCC it was completed using the micro CCC forceps. Hydrodissection was performed and rotation of nucleus done followed by reformation of anterior chamber with a viscoelastic agent. Endocapsular phacoemulsification and aspiration of nucleus was done using the divide and conquer technique. The machine parameters were varied according to the hardness of the cataract. The infusion bottle height was adjusted according to the anterior chamber stability. The residual cortex was removed using the bimanual irrigation and aspiration handpiece. The capsular bag was then filled with a dispersive ophthalmic visco-surgical device. The incision size was enlarged to 2.2mm to fit the outer diameter of the cartridge tip (D cartridge) of microincision IOL injectors. The 360 degree square edge acrylic lens (MICRIOL PLUS Lens) was taken from its container and loaded into the IOL injector with D cartridge and inserted into the main incision and the IOL was delivered inside the eye. MICRIOL PLUS lens is a single piece ultrathin lens with 4 haptics which are designed to provide wider angle of equatorial contact and more reliable centration. The ophthalmic viscosurgical device was aspirated using irrigation / aspiration cannula through the same incisions and at the end of the procedure the internal diameter of the main incision was measured using the 2.2mm measuring guage. Stromal hydration of the corneal wound and side ports were performed postoperatively. The operating surgeon did not report any difficulty in negotiating the phaco probe or any other instrument through the incision. Post operative pad and bandage was done. On next day slit lamp examination was performed. The patients received topical antibiotic steroid drops for 6 weeks and cycloplegics for 2 weeks. Examinations were done at 1 and 7 days and at the end of 1, 3 and 6 months postoperatively. Observations were done with pupil fully dilated. At every visit, slit lamp biomicroscopy, capsule opacification, and IOL centration were evaluated. Visual acuity, IOP measurements and fundus evaluation was also done.

RESULTS
The major outcomes measured were the postoperative visual acuity as well as intraoperative and postoperative complications. There were 55 males (55%) and 45 females (45%). Patients were included irrespective of sex. The age of the patients varied between 10 to 70 years. Maximum patients (72%) were in the 51- 70 years age group. Lowest number of patients (7%) were in the age group of 10-30 years. The mean age in our study was 54.47 years (Table 1). Combined cataract was the most frequent type of cataract encountered (26%) in our study followed by nuclear cataracts (25%) and posterior subcapsular cataracts (21%).(Table 2). Preoperative visual acuity ranged between 6/24 and hand movements with a median value of 6/60. The most common operative complication that we encountered was striate keratopathy in 21 patients (21%) but that was not seen to interfere with the final visual outcome. 2 patients who had posterior capsular rent with vitreous loss had persistent macular edema with visual status of 6/36 and 6/60 at follow up. Residual superior cortex was seen in 2 patients (2%) but both had good visual outcome since the pupillary axis remained clear. 2 patients (2%) had corneal oedema, 1 patient (1%) had extension of capsulorrhexis, and 1 patient (1%) had IOL decentration but the final visual acuity was 6/9 or better in all the four cases. Only 2 patients had a visual acuity less than 6/60 (1 each due to persistent macular edema and CNVM). (Table 3). Post operatively, at 6 months, majority i.e. 93 patients (93%) had best corrected visual acuity of 6/9 or better, whereas 7 patients had visual acuity of 6/12 or less. (Table 4). The causes of decreased visual acuity (less than 6/12) were posterior capsular opacification in 4%, persistent macular edema in 2 % and CNVM in 1% patient who had soft drusens preoperatively.(Table 5).

DISCUSSION
The major advantage of microcoaxial phacoemulsification is an improvement in control of most endocapsular surgery steps. Because visocoelastic material does not leave the eye easily through these small incisions, the anterior chamber is more stable during capsulorrhexis construction and there is a less likelihood for an errant capsulorrhexis to develop. Hydrodelineation and hydrodissection can be performed more efficiently because of a higher level of pressure buildup in the anterior chamber before eventual prolapse of viscoelastic material through the microincisions. Stable anterior chamber is also advantageous when weak zonules are present. The surgical technique for C-MICS is the basically the same as for conventional phacoemulsification , hence no learning curve is required . Besides with the availability of IOLs in the market to suit these microincisions ,the surgeon does not need to compromise on the quality of IOL nor is there any need to enlarge the incision, rendering the procedure a truly microincision procedure.

In our study the visual outcome after microcoaxial phacoemulsification was evaluated by recording the visual acuity of the patients operated for cataracts in the follow up period.72% patients in our study belonged to the age group of 51 to 70 years (72%), lowest being in the age group of 10 to 30 years (7%). The mean age in our study was 54.47 years. In the study done by Abhay Vasavada et al11, the mean age group was 54.23 years (range 39 to 73 years) and in the study done by Arup Chakraborti12 , mean age group was 62 years (range 46 years to 72 years). This is because most common types of cataracts are age related. Combined cataract was the most frequent type of cataract encountered (26%) in our study. Nuclear cataracts and posterior subcapsular cataracts were the next commonest types. In our study endocapsular phacoemulsification using the divide and conquer technique was used to emulsify the nucleus. The endocapsular phacoemulsification technique decreases the endothelial cell loss and postoperative corneal oedema which is more common when the phacoemulsification is performed in the anterior chamber. This finding is supported by the study conducted by Victoria W. Y. Wong et al13 . Striate keratopathy was the most frequent complication encountered in our study (21%) followed by residual cortex (3%) and posterior capsular rent (PCR) with vitreous loss (2%). The findings were consistent with other studies done earlier. In the study done by Amar Agarwal et al14, 18 patients (5.9%) developed corneal oedema, 5 patients (1.6%) developed posterior capsule rupture, 3 patients (0.9%) developed cystoid macular oedema and 1 patient developed age related macular degeneration. Because the anterior chamber is stable during MICS, management of PCR becomes much easier. Best corrected visual acuity at 6 months follow up was 6/9 or better in 93% of cases. Posterior capsular opacification (4%) was the most common cause of vision less than 6/9 (target vision) followed by persistent macular oedema (2%). These findings are consistent with the other studies conducted by Amar Agarwal et al14, Arup Chakraborti et al12, Jorge L. Alio15 et al and Victoria W. Y. Wong et al13. Rapid visual rehabilitation is considered to be one of the advantages of this procedure. The information available to date on results from surgery with the coaxial microphacoemulsification procedure shows that it is a relatively safe and effective operation. All reported cases reflect decreasing complications, better visual outcome and early rehabilitation. With this method comparison of the complications with those of standard phacoemulsification technique is difficult due to relative paucity of reported data, the lack of standard techniques and the fact that improved surgical technique and instrumentation have apparently decreased complications in all types of cataract surgery.

CONCLUSION
The ability of coaxial microphacoemulsification to:
1) To allow the surgery using the same technique as that of conventional phacoemulsification, without warranting the need for a learning curve.
2) Limit the hospital stay to 24 hours and therefore reduce the expenses.
3) Permit the patient unrestricted activity after discharge and
4) Reduce the intra operative time as well as postoperative recuperative times gives it distinctive advantages.

It should definitely be the procedure of choice for both patients as well as surgeons for the removal of cataracts .With the change in the trend from small incision (>2.0mm) to minimal incision (<2.0mm) surgery, microcoaxial phacoemulsification offers a new modality in the management of cataracts of all densities. Though still in its early years, with improved and specific  instrumentation and manoeuvers, increasing experience and newer IOL materials, it may fast become the preferred choice of all cataract surgeons.

ACKNOWLEDGEMENT
Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.

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