|Year : 1979 | Volume
| Issue : 4 | Page : 34-38
Intraocular lens Implants
Daljit Singh, Mohinder Singh, Ashok Bajaj
Department of Ophthalmology, Medical College, Amritsar, India
Professor of Ophthalmology, Medical College, Amritsar-143001
|How to cite this article:|
Singh D, Singh M, Bajaj A. Intraocular lens Implants. Indian J Ophthalmol 1979;27:34-8
Intraocular lens implant is an optical device meant to replace the cataractous lens in its intraocular position. The first artificial lens was put in the posterior chamber after extracapsular cataract extraction by Ridley in 1949. Since then many designs of intraocular lens implants (pseudophakoi) have been used by various workers. Broadly speaking, these artificial lenses may be divided into the following types:-(I) Posterior chamber lenses (Ridley's), (2) Pupillary plane lenses, (3) Iris clip lenses and iridocapsular lenses (Binkhorst's), (4) Angle supported lenses (Choyce).
The first type was given up long ago, whereas the last three varieties have received extensive trials in different parts of the world during the last 30 years. The lenses of Binkhorst, Worst and Choyce are the best known.
| Material and methods|| |
We have operated upon 110 cases. The age and sex distribution has been summarised in [Table - 1]. The following intraocular implants have been used:
Two footed iris clip lenses : 101
Angle supported lenses . 7
Pupillary plane lenses . 2
The two-footed iris clip lenses were made by Shah and Shah, Calcutta. The lenses were manufactured locally.
The optical portion of the lens is made of polymethylmethacrylate, while the haptics of the iris clip lens are made of titanium.
No conjunctival swab was sent for culture. Genticyn eye drops were put frequently one day before operation and on the morning of the operation, 500mgm of acetazolamide was given orally two hours before surgery. Some patients received 100 ml. of oral glycerine or i/v mannitol drip one hour before operation. No mydriatic was ever put before operation.
The lens was sterilised by dipping it in boiling water for 2 minutes.
All adults were operated under local anaesthesia Little or no bulbar massage is applied. General anaesthesia was used in young patients.
The conjunctival sac is cleaned with two swabs dipped in solution of penicillin and streptomycin. A 3 mm wide limbal based conjunctival flap is made from 3 to 9 O'clock. The incision consists of first vertical cut at the limbus, second horizontal splitting of the cornea for about 1mm, and the third vertical cut opening the anterior chamber about 3-4 mm anterior to the first vertical cut (4).
All intracapsular lens extractions were done with Amritsar method. When planned extracapsular lens extraction was done, the lens matter was washed out with Fuch's syringe, using normal saline. Sterile air was injected into the anterior chamber to settle the vitreous. The sterile intra ocular lens implant is placed in position with utmost caution to avoid injury to the endothelium. One or two peripheral iridectomies were done. After tying the preplaced stitches, two or three extra stitches were applied. Sterile air was injected into the anterior chamber. Conjunctival flap was replaced. A drop of 4% pilocarpine was put. Subconjunctival injection of 4 mgm of dexamethasone was given. Pad and bandage was applied to both the eyes.
Chloramphenicol was given every six hours for three days. Dexamethasone 4 mgm was given in divided doses on the second day. The dose was decreased by 1/2 mgm every day and the drug was discontinued by 9th day. The bandage was kept open during the day time, starting from second day. Dexamethasone eye drops were put every hour throughout the day. 4% pilocarpine was put twice a day. The eye was bandaged at night. The local instillation of dexamethasone was gradually reduced to 4-5 times a day by the fifteenth day, when the patient was discharged with the following instructions: 1. To continue putting dexamethasone drops, 4-5 times a day for the next three months. 2. To put 1 % pilocarpine drops twice a day. 3. To keep an eye shield applied for the next two months. This protects the eye from trauma. 4. To have first two check-ups every two weeks and later on every two to three months.
The corrected visual acquity is recorded two months after the operation and on every visit thereafter. The patient is examined with a slit lamp microscope on every visit.
| Results and discussion|| |
[Table - 1] shows the age and sex distribution of the patients.
Intracapsular cataract extraction was done in 92 cases, whereas planned extracapsular cataract extraction was done in the remaining 18 cases. All the latter cases were young. They include 4 cases of traumatic cataract and 2 cases of congenital cataract.
[Table - 2] shows the immediate post-operative complications.
It will be seen that the most frequent immediate post-operative complication was severe iritis, many of them developing hypopyon (5). Such severe reactions are rarely encountered by the surgeons in the west. It is probable that the dark irides of our patients which react rather severely to the presence of the pseudophakos. Such cases of uveitis needed subconjunctival injections of dexamethasone to clear up the inflammation. Many lenses had to be removed. To overcome this serious problem, we started frequent local instillation of dexamethasone drops from second day onwards, of course along with gradually decreasing doses of oral steroids. The incidence of iridocyclitis in this way has come down from 39.2% to mere 2%.
The two loop lenses are actually designed to be used for fixation inside the capsular bag after extracapsular cataract extraction. But we have used these lenses after intracapsular extraction as well. Their stability seems to have been helped by inflammatory adhesions.
Four cases of dislocation of the implant were seen in the immediate post-operative period. In two cases there was severe hypotony at the time of surgery. Such a happening might have been prevented by filling the posterior chamber with saline before putting air into the anterior chamber. The other two dislocations were due to ineffectiveness of 1% pilocarpine drops. The first two dislocated lenses were removed by emergency operation. The third dislocated lens was repositioned by surgery. In the fourth case, the lens slipped posteriorly into the vitreous. It was removed by surgery without any damage to the eye, using a binocular indirect ophthalmoscope.
The late post-operative complications have been summarised in [Table - 3].
Dislocation occured in two cases, nearly one year after surgery. In one case it was due to trauma. This lens was repositioned by closed rotation of the head and fixation by 4% pilocarpine. In the second case, the implant was removed on patient's request.
Six cases required needling for after cataract.
Removal of implants
[Table - 4] shows the reasons for the removal of implants.
The cases have been followed from 3 to 14 months with the average follow up being 160 days. The average number of visits per patient were 5.
[Table - 5] shows the visual results.
The average visual acquity achieved is 0.46 (a little less than 6/12). In comparison the average visual acuity achieved by Binkhorst (0.65) in his first 694 cases is admirable, 2. The possible cases of poor visual acuity in our cases are: 1. severe uveal reaction, 2. greater dispersion of pigment.
Some progress will be noticed in the second series of 50 iris clip implants (average vision of 0.53) compared to the early series of 51 cases (average vision of 0.42).
Advantages of intraocular lens implants
To quote Harold Ridley: "It can be stated quite simply that with an artificial intraocular lenticulus we can restore the eye to as near its precataractous optical state as man will ever be able to do, unless in centuries ahead a method discovered of transplanting a living human lens".
Intraocular lens implantation causes plenty of additional surgical trauma. The long term effects of intraocular lens implants in our patients with dark iris are yet to be known. Even in the best hands and under ideal circumstances the list of post-operative complications is very big.
The most important indication of an intraocular lens implant is a unilateral cataract where the aphakic eye is likely to become amblyopic. Many of these patients can be helped with contact lenses. But there are others (young, old and infirm) who may not be able to manage a contact lens comfortably. This is especially important in our country where the hygienic conditions are least favourable for most people. Young patients having congenital cataracts, unilateral cataracts or traumatic cataracts are most suitable. Intelligent adult patients can be given a choice between a contact lens and an intraocular lens implant.
1. Patient's anxiety over the procedure, 2. high myopia, 3. poor results in the first eye with implant. 4. one eyed patients, 5. postoperative follow up impossible. 6. diabetes mellitus. 7. history of uveitis. 8. complicated cataract, 9. endothelial corneal dystrophy. 10. rubella cataract.
Compared to the early lenses of Ridley, Choyce and Binkhorst, the lenses available to us are fairly good. But there is further scope for great improvement and standardization.
| References|| |
|1.||Nirankari, M.S. and Singh, D., 1973, Eastern Arch. Ophthal.. 172. |
|2.||Nordlohne, M.E., 1975, The intraocular implant lens, Development and results with special reference to Binkhorst's lens, The Hague, Junk. |
|3.||Ridley, H., 1964, Trans. Ophthal., Soc. U.K., 84, 5. |
|4.||Singh, D. and Singh, M., 1977, Proceedings of all India ophthalmological society (under publication). |
|5.||Singh, D., Singh, M. and Singh, A., 1977, Proceedings of all India ophthalmological society (under publication). |
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]