|Year : 1989 | Volume
| Issue : 2 | Page : 73-74
Anterior chamber intra ocular lens implantation
Ranjini, Valanjambalam, Cochin, India
Ranjini, Valanjambalam, Cochin
Source of Support: None, Conflict of Interest: None
The role of A.C. IOL in modern implant surgery has become somewhat debatable, since, the choice procedure to day is undoubtedly an ECCE with a PC lens implant preferably in the capsular bag. Even so, anterior chamber lens implantation has its definite indications. As such it is necessary for the implant surgeon to be familiar with the latest technique in this modality of surgery as well. Many of the complications of earlier rigid model AC IOLs were mainly due to defective lens design. With the advent of new generation flexible one-piece PMMA AC lenses, many of these complications have been eliminated. A.C. IOL implantation, although less frequently done now, has its own legitimate place in modern IOL surgery.
Keywords: AC IOL = Anterior Chamber Intra Ocular Lens PC IOL = Posterior Chamber Intra Ocular Lens ECCE = Extra Capsular Cataract Extraction.
|How to cite this article:|
Raju N. Anterior chamber intra ocular lens implantation. Indian J Ophthalmol 1989;37:73-4
| Introduction|| |
With the universal acceptance of posterior chamber lens implantation as the standard procedure of IOL implantation, the significance and importance of A.C. IOL has been greatly reduced. Therefore the question might naturally be asked as to what is the relevance of such a subject in this context. It may be remembered that even today there are certain clinical situations which might warrant an A.C. IOL implant. Also, many A.C. IOL implants have been done in the past and we have to deal with these cases in our daily practice and may even have to explant them. There are many surgeons who perform A.C. IOL implantation as a primary procedure after an intracapsular cataract extraction even now. We should not overlook the significant number of eminent ophthalmic surgeons who have extensive experience with anterior chamber lenses as a primary procedure and who even now continue to report excellent results with these lenses.
Till the early 80's A.C. IOLs had been enjoying universal acceptance, when unfavourable reports mainly relating to its long term complications, began to appear. A few factors probably contributed to the early popularity of these lenses. Firstly the implantation is technically easier following a routine intracapsular cataract extraction and skill in microsurgery is not imperative. Secondly, the surgeon did not have to alter his surgical technique from intracapsular cataract extraction to extracapsular. Thirdly, the immediate outcome of the surgery was often quite rewarding. In fact many implant surgeons of great repute to day probably began their implant surgery with anterior chamber lenses. The early lenses available were mostly the rigid ones. Perfect sizing of the lenses was of extreme importance. Very often the inadvertent insertion of a too small or too big lens led to serious and often disastrous consequences. Viscoelastic materials were not freely available then and implantations were more traumatic. It was therefore not quite surprising that a lot of complications followed the earlier model A.C. lenses. The incidence of UGH syndrome was relatively high due to the poor finish of these lenses. Moreover the unstable vaulting characteristics resulted in increased incidence of intermittent touch syndrome and iris chafing. Many A.C. IOLs had round, small diameter, closed loop configuration for the haptics and these tend to erode into iris and the angle of the anterior chamber. The broad area of loop contact caused goniosynechiae and glaucoma. Another causative factor was the poor finish of these lenses with sharp optic and haptic edges, resulting in a chronic inflammatory reaction after many years, often leading to pseudophakic bullous keratopathy. It was therefore no wonder that anterior chamber lens implantation soon fell into disrepute.
Although extracapsular cataract extraction with a PC IOL implantation is the choice procedure to day, the occasional need for A.C. IOL arises in cases of large posterior capsular rupture with vitreous loss, secondary lens implantation and lens exchange procedures.
MODERN TRENDS IN AC IOL IMPLANTATION
Taking all the flaws with the rigid loop lenses into consideration a totally new concept has been evolved in the design and finish of the modem anterior chamber lenses. The modem flexible one piece lenses have haptics of the open type with flat foot plate design. The flexibility may be the cause for the lower incidence of tissue reaction, iris tuck, uveal chafing and lens malposition.
The absence of the optic-haptic joint causes little chance of defective angulation. The positioning holes have been eliminated thus reducing tissue growth into this and making removal easier if necessary. Modem AC IOLs have a smooth lens edge and modern tumbling methods give the optics and haptics perfect finish. They are so fixated that excess contact with constantly (thus reducing iris chafing) moving iris and ciliary body is avoided.
The use of visco-elastic materials like Sodium hyaluronate and viscous materials like Methyl cellulose have added further safety to AC IOL implantation, ensuring protection of the sensitive corneal endothelium during surgery. While evaluating the AC IOLs it must be remembered that these lenses are now mostly being implanted under the most difficult clinical situations which by itself are prone to develop post-operative complications. The increased incidence of complications of AC IOLs must therefore be viewed in this perspective also. The clinical efficacy and superiority of PC IOL is unquestionable; but when a necessity of AC IOL implantation arises, there are better and safer models of lenses which seem to produce only negligible complications. The Kelman multiflex lens is an example.
| Conclusion|| |
It has now been conclusively proved that many of the complications of earlier model AC IOLs were due to the inherent defects in the design of the lenses. With the evolution of the modem new generation lenses, these have largely been overcome. While PC IOL implantation is the choice procedure today, situations like large rents in the posterior capsule with vitreous loss, lens exchange procedures and secondary lens implantation often necessitate an AC IOL implantation. The modem implant surgeon should therefore be familiar with these procedures also. To condemn all anterior chamber lenses universally is quite unfortunate and rather unfair since it is clear that we will always have a need for these lenses. We should therefore continue our efforts to further improve and develop new lens designs that are ideal for AC IOL implantation rather than adopting a negative attitude.
| References|| |
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