Australian Journal of Ophthalmology. (1979), 7, pp. 229-23 1.

REPORT ON THE USE OF HEMA IN INTRAOCULAR LENSES*

Ronald Parker, F.R.A.C.O. D.O. 577 Toorak Road Toorak VIC. 3142.

Aboirad Hema has been used for I.O.L. implants with no apparent complications in a seventeen month follow-up period so far. Sterilization by autoclaving, one-piece construction and lack of adhesion to corneal endothelial cells are cited as probable advantages in 1.0. L. designs. Hema implants are under study in Japan, India and South Africa. The procedure is investigational and the lenses are not marketable

INTRODUCTION In the mid-eighteenth century, Casanova (known better by his title The Great Lover), met Tadini, an Italian born itinerant Ophthalmic Surgeon, who showed him a little box of tiny crystal balls which Tadini claimed he felt sure he could insert behind the cornea in place of the opaque human lens. In 1795 Casaamata at- tempted to place a glass lens implant but it went straight to the floor of the eye.

In this presentation I wish to report the early results of using soft hydrophilic plastic lens ma- terial for intraocular implants after cataract removal.

My present personal choice of procedure is still the use of the two loop irido-capsular Binkhorst lens in conjunction with closed-eye Extra-cap- sular cataract extraction for probably 95% of my implant indicated cases. It has a fifteen year his- tory of safety.

With the availability of so many lens designs it may well be asked Why introduce yet more designs?

We do not yet have the perfect artificial lens implant - all are compromises.

Adequate sterilization of implants has been of some concern recently, together with some doubts about complete removal of chemical from the implant surfaces by soaking before insertion.

Ethylene oxide sterilization allows dry pack delivery of a lens but it should still be soaked in balanced salt solution before implanting.

It appeared that an autoclavable lens would be desirable, both from the point of view of initial sterilizing, but also because one could autoclave it in the theatre again if necessary and remove the need to send the lenses back to the manufacturers for resterilization.

Also, one-piece construction was known to cause less anxiety regarding the dangers of crevices which could harbour organisms and junctions of dis-similar materials where electro- chemical reactions could occur.

All lenses since Ridleys in the early 1950s were of perspex (ie, P.M.M.A.) and autoclaving of this

*Presented at the Annual Congress of the Royal Australian College of Ophthalmologists, Singapore. May 4 - 1978.

REPORT ON THE USE HEMA 229

material caused warping after softening so'liquid soaking or gas sterilization was necessary.

Hema had found great acceptance in the con- tact lens field and the concept that soft contact lenses were kinder to corneal and conjunctival surfaces led to the philosophical concept thaJ it may be kinder to intraocular tissues as well.

At the time of producing the first lathed prototypes, Dr Herb. Kaufmann was demon- strating that just mere apposition of endothelium and a smooth perspex surface left torn-off en- dothelium cells clinging to the P.M.M.A. surface.

Coating perspex with methyl-cellulose 1% or with a thin Polymacon film reduced this tearing- off tendency. Hydrated Hema showed no such tendency and the human lens itself and iris tissue showed no such adhesive tendency. Coating a lens during the surgery may remove endothelial touch in the theatre but does not prevent the damage from the inevitable post-operative epi- 'sodes of touch which occur in face down positions or in rubbing.

Simultaneously, a return to planned extra- capsular cataract surgery was gaining numbers due to the,wider use of micro-surgery technique, to the mounting evidence from Dr C. Binkhorst and from Dr Jan Worst that the incidence of cystoid macular oedema and of retinal detach- ment were reduced and to the evidence that an eye which retained its compartmentalization was a more physiological model.

Hence this prototype, based on the e&ly Ep- stein Collarstud design, lends itself best to the workability of Hema, and to a reasonable mimic of the human lens it is to replace.

The round pupil is anatomically, phy- siologically, optically and cosmetically desirable.

The implant is intended primarily for insertion 'into the capsular bag; hence a good clean extra- capsular technique is necessary with careful at- tention to obtain a good inferior anterior capsular flap.

The nature of the design keeps any slight re- sidual cortical material well peripheral and it cannot enter the pupil zone. If the lens is im- planted after intra-capsular surgery, then it is ad- visable to perform iris suture fixation in addition

230

to avoid sub-luxation or dislocation during pupil dilation for fundus examination.

The combination of extra-capsular technique and presence of the artificial lens in the post-iris position should hopefully reduce the vitreo-re- tinal traction effects as seen after intra-capsular technique.

Certainly irido-donesis and pseudo-phako- donesis are much reduced or almost absent.

Additional iris sutures may be required in cases of traumatic deficiencies of iris tissue and/or pupil distortion.

Disadvantages ( 1 ) The main disadvantage lies in its unknown long term performance as an intraocular plastic. Little published. data is available. Lamellae of Hema placed within the stroma of cornea for refraction alterations have remained clear and without apparent reaction for five years to date.

A Japanese Ophthalmologist reported verbally in October 1976, that a soft lens implant had been in situ without complication for one year at that time.

Dr Mehta (India) has implanted thirty soft lenses but has only a six month follow-up so far.

In my small series, four implants of the collar- stud type have been in situ for periods from four months to seventeen months. Three were placed after extra-capsular extraction and one after in- tra-capsular extraction. Iris fixation suture was used in the intra-capsular case.

(2) A second disadvantage is the weight of the lens compared with other lenses which have been progressively reduced to an almost weightless state. However, weight per se was not the big problem with early lenses but rather inertia of a lens with poor fixation and thin or sharp pupil or angle supports causing tissue tearing with sudden eye movements and sudden directional change in eye excursions. Even distribution of weight over a round pupil should reduce these inertial effects while capsular fixation is occurring.

(3) A third disadvantage is that a pars plana approach will be needed if posterior capsulotomy becomes necessary.

This is not a serious disadvantage and present micro-apparatus will facilitate the procedure if it

AUSTRALIAN JOURNAL OF OPHTHALMOLOGY

becomes necessary. So far, the extra bulk of the prosthesis lying against the posterior capsule, and keeping traces of cortical material off it, appears to have had a protective influence against pos- terior capsule thickening and clouding.

One patient had a protracted post-operative uveitis but this was an eye with a hyper-mature cataract which showed a hypopyon on the second post-operative day. No growth from A.C. Punc- ture was obtained and the eye settled to the quietness of the others.

A final disadvantage is the difficulty in having the lenses made and I wish to acknowledge the help and co-operation from the staff of the O.P.S.M. Contact Lens Department in Melbourne.

Bibliograohv I .

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- . Report on U . S . lntraocular Lens Symposium. Los Angeles. March. 1976. Kaufman. H. E., J . K u t ~ : Endothelial damage from intra-ocular lenses. Annual Meeting I I of American In- tra-ocular Implant Society. La5 Vegas. October 1976. Mehta K.. R e o r t on US. Intra-ocular Lens Symposium. Los Angeles. arch. 1978. Fechner. P. U., Methyl Cellulose in Lens Implanta- tion. American Intra-ocular Implant Society Journal. Vol. 3, No. 3 and 4. July. October. 1977. Binkhorst, C. D.. Lens implants classified accordin to method of fixation. Br. J. Ophthal . Vol. 5 I ( 1967). p h 2 . Galin, M. Toxicity of Ocular Plastics. Amer. J. Ophthal . Vol. 79. No. 4 (1975). Jaffe. N . S., The Lens: A n n u a f k g o r t . . Arch Ophthal. Vol. 90 ( 1973) p. 136. Shepard, D.. The Intra-ocular Lens Manual. 1977. Katz, J.: Kaufman. H. E.. Goldberg. E. P.. Sheets. J . W.. Prevention of endothelial d a m a i e from intra-ocular lens insertion. Trans. Am. Acad. hph tha l . and Oto. 83:

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204-212. 1977.

The final common path for all ocular movements are from the paramedian pontine reticular formation for horizontal movements, and from the pretectal region for vertical movements. For horizontal movements the ipsilateral VI nerve is stimulated and the opposite medial rectus nucleus in the midbrain via the median longitudinal fasciculus. Concomitant inhibition of the ipsilateral medial rectus and Contralateral lateral rectus also occurs. The interreaction between excitation and inhibition is obviously more complex when vertical eye movements are generated.

Scientific Foundations of Ophthalmology M.D. Sanders Edited Edward Perkins and David Hill Heinemann, 1977.

REPORT ON THE USE HEMA 23 1