|Year : 1990 | Volume
| Issue : 1 | Page : 1-2
A decade in ophthalmology
CBM Ophthalmic Institute, Little Flower Hospital, Angamally-683 572, Kerala, India
S T Fernandez
CBM Ophthalmic Institute, Little Flower Hospital, Angamally-683 572, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Fernandez S T. A decade in ophthalmology. Indian J Ophthalmol 1990;38:1-2
| Cataract and intra ocular lens implantation|| |
Perhaps the most significant phenomenon that ophthalmology witnessed in the last decade is in the field of cataract surgery. Sweeping changes are tried out every day both in the type of intra ocular lenses and in the technique of surgery.
| Intra ocular lenses|| |
It can be safely asserted that improvement has taken place in the method of manufacturing of the lens. Better cleaning methods, tumble polishing, one piece lens etc. have all resulted in bettering the quality of the lens leading to lesser post-operative complications. The significant changes that have been made in the type of lens models are as follows:
1. To avoid the difficulties in vision owing to slight decentering of the lenses, 6.5 mm or 7 mm optics are being used instead of 6 mm. The centering holes have been given up completely in some types or only one or two holes are used.
2. More and more single piece lenses are being used now. Disc lenses with flexible closed loops are now being tried.
3. Coated lenses have been introduced in the market. The present lenses create uveal reaction and pigment adhesions. These lenses damage the endothelium as well. Healon or Visilon has to be used to avoid this-damage.
Now Heparin coated lenses are marketed by Pharmacia to avoid such reaction. Flurocarbon bonding or Teflon coating of the lenses has been experimentally tried.
4. Multifocal lenses: Although it is too early to make any assessment, the initial experience with these lenses has shown encouraging results. There are different designs of multifocal lenses. Pharmacia and IOLAB have produced lenses for distant and near vision, whereas Allergan has produced the Array design by which all distances from infinity to the near point, are expected to be focussed by this lens. The third approach is adopted by 3 M company. These lenses are similar to Fresnell prisms. This multifocal IOL has the refractive surface on the anterior part of the lens and the diffractive one on the posterior.
| Surgical techniques|| |
Anti-inflammatory drops like Ocufen and Indomethacin have been found to be effective against prostaglandins.They are found to keep the pupil dilated during surgery and prevent post-operative inflammation.
Peribulbar anaesthesia seems to give excellent results, with least complications. The painful facial block and its complications are thus avoided.
Suturing of the posterior chamber lenses into the sclera has given good results in secondary implantations in previous intra capsular surgery and also in cases of subluxations of the cataract. Special suturing techniques and needles have been introduced for this type of surgery.
Small incision cataract surgery and foldable lens insertions are being performed but the technique has not yet become popular.
Phakoemulsification is used in this technique to remove the nucleus. The instruments used for this are now more efficient, easier to handle, small and cheaper, from atleast the Western standards. The advantage of foldable lenses is that they allow insertion through a small opening which gives rise to less post-operative trauma and astigmatism. Silicon, hydrogel and compressible polymethyl implants are being tried, but it has not yet become popular because of certain limitations.
Significant changes have been made in the techniques of anterior capsulotomy. Instead of the can opener method horizontal incisions are now made. The lenses are introduced 'inter-capsular' or in an 'enveloping' method. Now a clear cut round hole in the anterior capsule has been described, namely capsulorhexis. By this method irregular edges of the capsule and decentration of the lens are avoided.
Studies are still going on, on two important aspects - one to find out how to avoid thickening and after Cataract formation in the capsular bag. Chemicals, enzymes, sand blasted cannulas, ultrasonic cleaners and lasers are being tried to clean the capsular bag off epithelial cells. We are yet to find a solution to this.
The second aspect is how to maintain accommodation. Refilling of the capsule with a silicon balloon which might give a certain amount of accommodation is being tried. The experiments have been successfully tried in animals by Okihiro Nishi of Japan. But suturing of the capsule has been found to be difficult in human beings.
Yag Lasers have become a boon for opening up holes in the thickened capsules, avoiding needling. This non invasive method of surgery is becoming popular because it can be done as an out patient procedure and without local injections.
Though extra capsular versus intra capsular extraction is still a controversy, more and more surgeons are switching over to excellent extra capsular extractions under microscopes, giving good post-operative results with lesser post-operative complications especially retinal detachments.
Judging from the phenomenal changes which have taken place in the last decade or so in cataract and IOL surgeries, we can certainly hope that the new decade and the early next century will usher in a veritable revolution in this field - perhaps a new or a near natural replacement or transplantation of the lens.