There are numerous benefits to using an injection system for inserting an intraocular lens (IOL) in the capsular bag. Such systems place the IOL in the eye without the lens touching the conjunctival or corneal surface. This is postulated to decrease the risk of endophthalmitis. Similarly, it avoids manipulation of the IOL with a forceps or lens hooks, which may scratch or leave marks on the IOL optic.1,2 Less wound manipulation occurs with an injector system, and the wound required for implantation is smaller than with other methods.3–6 The small incision induces less astigmatism.7 An injection system is relatively easy to use, and there is minimal manipulation of the IOL optic and haptic. Thus, transition of the haptic and optic through the injection system should be easy. Resistance will likely damage the IOL, which could lead to surgical complications.
Patients and Methods
The charts and administrative records of 202 consecutive eyes that had cataract surgery with implantation of a Sensar AR40 IOL (Allergan) were examined. The patients were treated 1 day preoperatively with ketorolac tromethamine (Acular®) 1 drop 4 times a day and ofloxacin ophthalmic solution 0.3% (Ocuflox®) every 2 hours when awake in the operative eye. The eyes were dilated with phenylephrine 2.5%, cyclopentolate 1%, and diclofenac 1 drop in the operative eye 3 times 5 minutes apart. One drop of proparacaine 0.5% was given before instillation of diluted povidone–iodine solution (Betadine®). The eye was then covered with lidocaine 1% jelly before surgery.
All surgeries were performed by 1 surgeon (J.G.). The eye was prepped with Betadine solution and draped. A lid speculum was placed so that the lashes were trapped under the drape. A side-port incision was made, and 250 μL of preservative-free lidocaine 1% was placed in the anterior chamber. Viscoelastic material was instilled in the anterior chamber. A 2.8 mm corneal incision was made, usually on the steepest axis, with a diamond keratome. A continuous curvilinear capsulorhexis was created with a Utrata forceps and hydrodissection performed. Phacoemulsification was done using the divide-and-conquer or phaco-chop technique. The cortex was removed by irrigation/aspiration. At the end of the cortical removal, viscoelastic material was placed in the capsular bag and anterior chamber. The wound was enlarged to 3.0 to 3.2 mm.
The operating nurse prepared an Unfolder (Allergan) cartridge. A cohesive viscoelastic material was placed in the cartridge per the manufacturer's instructions. The IOL was placed in the cartridge, and the wings were folded. The cartridge was inserted in the rod and handed to the surgeon. The surgeon ensured that the blue leading haptic of the IOL was in the barrel of the cartridge. The cartridge was inserted through the wound and placed on the anterior capsule plane. The screw was turned so that the leading blue haptic was inserted into the left side of the capsular bag. The surgeon ensured that the tip entered the capsular bag. Once the optic was extruded from the cartridge, it was placed in the capsular bag by downward manipulation. The cartridge inserter was rotated clockwise to ensure that the trailing haptic was in the capsular bag. The lens usually did not require rotation with a lens hook to center it.
There were 3 complications using the Unfolder system that were related to the inexperience of the assisting nurse. In these cases, the leading haptic was pinched between the 2 flanges of the Unfolder cartridge. Advancing the IOL caused resistance and tearing of the haptic from the optic. As soon as the surgeon realized there was no leading haptic, the insertion was stopped before the lens was extruded into the eye. A new lens was placed in the cartridge by the operating surgeon under the microscope. The lens was inserted using the Unfolder in all cases. Postoperatively, the best corrected visual acuity (BCVA) in the 3 patients was 20/20 (Table 1).
In cases in which the IOL was inserted without difficulty, there was no resistance or haptic stretching. With increasing experience, the surgeon could judge the resistance and determine whether the IOL was properly loaded.
One patient had a posterior capsule tear during cortical aspiration, requiring a vitrectomy. The surgeon used the Unfolder to place the leading haptic in the sulcus and extrude the lens into the iris plane. The trailing haptic was manipulated into the sulcus using the Unfolder system. A lens hook was used to capture the optic under the anterior capsule. Postoperatively, the patient had mild corneal edema and a BCVA of 20/20 within 1 week (Table 1).
The patients were examined 1 day and 42 days postoperatively. All IOLs were well centered.
This is the first report of a 6.0 mm optic acrylic IOL implanted with a cartridge system. Ng and coauthors8 describe using the Unfolder system for silicone IOLs with good results. Even with minor complications related to the system, all patients had a visual acuity of 20/20 or better. Olson et al.9 report using the Unfolder system and silicone lenses. There were no cases of optic damage or haptic deformation. Hagan10 found similarly good results with a 5.5 mm acrylic IOL implanted with a Monarch system (Alcon).
Using a cartridge system to insert IOLs provides numerous benefits. The incision is smaller than when a forceps is used.7 This should result in better wound sealing and less surgically induced astigmatism.7 A folding forceps, which can leave marks on the lenses, is unnecessary with cartridge systems,1 which require fewer instruments and manipulation. The IOL does not touch the corneal or conjunctival surface, preventing contaminants while entering the capsular bag. The Unfolder provides controlled release of the haptics and optic, which allows directed release of lens into the capsular bag or sulcus.
The Unfolder system is based on a principle similar to that of the Allergan SI-40 system for inserting silicone IOLs.1,2 Instead of having a soft silicone tip at the insertion rod, a notched metal rod is used to capture the acrylic optic. Acrylic optics are more rigid than silicone ones and do not shear as easily; therefore, they do not require a silicone tip. The notched metal tip provides better control of IOL insertion. The insertion system allows smooth, controlled insertion of the haptics and optic in the capsular bag. It does not require manipulation of the trailing haptic with a lens hook.
The system requires experience for nurses and surgeons. For example, the optic and haptic must be precisely loaded, as shown on the diagram on the cartridge, to prevent pinching the leading haptic. Similarly, the surgeon must ensure that the leading haptic is in the barrel of the cartridge when inserting the IOL into the eye. If there is resistance to the insertion, the surgeon should stop and examine the cartridge and IOL.
In our study, the main complication was the result of improper loading of the IOL in the cartridge. When this happens, the leading haptic can be pinched in the flanges of the Unfolder cartridge. There was marked resistance when extruding the IOL, which alerted the surgeon (after some experience) that the lens was improperly loaded. Similarly, the failure of the leading haptic to appear out of the barrel of the cartridge alerted the surgeon that the IOL was not loaded correctly. Loading the cartridge under the microscope by the operating surgeon would obviate most loading problems.
The 1 complication that required the IOL to be inserted in the sulcus was easily performed using the Unfolder system. The Unfolder allowed manipulation of both haptics into the sulcus without touching the iris or the endothelial surface.
In summary, this is the first report of using an insertion system for a 6.0 mm optic acrylic IOL. If the IOL is placed in the cartridge correctly, with the leading and trailing haptics in the right place, its insertion should not be difficult. The insertion does not require manipulation of the IOL with a lens hook. All IOLs were well centered at all follow-ups, and none required rotation with a lens hook.
1. Gunenc U, Oner FH, Tongal S, Ferliel M. Effects on visual function of glistenings and folding marks in AcrySof intraocular lenses. J Cataract Refract Surg 2001; 27:1611-1614
2. Milazzo S, Turut P, Blin H. Alterations to the AcrySof intraocular lens during folding. J Cataract Refract Surg 1996; 22:1351-1354
3. Kohnen T, Lambert RJ, Koch DD. Incision sizes for foldable intraocular lenses. Ophthalmology 1997; 104:1277-1286
4. Kohnen T, Koch DD. Experimental and clinical evaluation of incision size and shape following forceps and injector implantation of a three-piece high-refractive-index silicone intraocular lens. Graefes Arch Clin Exp Ophthalmol 1998; 236:922-928
5. Kohnen T. Incision sizes with 5.5 mm total optic, 3-piece foldable intraocular lenses. J Cataract Refract Surg 2000; 26:1765-1772
6. Mamalis N. Incision width after phacoemulsification with foldable intraocular lens implantation. J Cataract Refract Surg 2000; 26:237-241
7. Kohnen T, Dick B, Jacobi KW. Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes. J Cataract Refract Surg 1995; 21:417-424
8. Ng DT, Francis IC, Schumacher RS, Alexander SL. Prospective study of 1 surgeon's experience with 115 cases using the Unfolder lens injection system. J Cataract Refract Surg 2001; 27:1437-1439
9. Olson R, Cameron R, Hovis T, et al. Clinical evaluation of the Unfolder. J Cataract Refract Surg 1997; 23:1384-1389
10. Hagan JC III. Initial experience with the MONARCH IOL delivery system for insertion of the 5.5 mm: ACRYSOF intraocular lens. Mo Med 1999; 96:555, 561–562