|Year : 1965 | Volume
| Issue : 3 | Page : 95-99
Follow-up studies in keratoplasty- Observations during last 5 years
|Date of Web Publication||22-Feb-2008|
R P Dhanda
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dhanda R P. Follow-up studies in keratoplasty- Observations during last 5 years. Indian J Ophthalmol 1965;13:95-9
|How to cite this URL:|
Dhanda R P. Follow-up studies in keratoplasty- Observations during last 5 years. Indian J Ophthalmol [serial online] 1965 [cited 2020 Aug 13];13:95-9. Available from: http://www.ijo.in/text.asp?1965/13/3/95/39225
The graft lives on its own nutrition during the first three weeks after surgery after which it starts becoming more and more dependent on the host. This change over from its own resources to those of the host is the critical period. Identification of sex chromatins made recently possible by electron microscopy showed that although physiologically from third week onwards, the graft starts living on the host, morphologically it retains its entity for much longer periods. One view is that the donor graft in due course of time is completely replaced by the host collagens and mucopoly-saccharides. There is however, also evidence that the donor graft is completely replaced by the host tissues in 2-3 years time. Tissue reactions between the donor and host should therefore be a theoretical possibility for many post-operative months. That is why the commonly made statement that no surgery is fraught with more uncertainties, so much out of control of the surgeon once the patient has left the operation table and so unpredictable regarding its ultimate fate as corneal surgery.
With this background it is easy to understand that follow-up studies in keratoplasty are far more important both for the patient from the point of view of his vision and for the surgeon to continue to observe the interesting life-span of a corneal graft.
Of the 206 patients operated for corneal grafting (243 keratoplasty operations) at this Corneal Surgery Unit during the first 4 years (1960-63), as many as 111 were followed up for one to four years upto the end of 1964.
It is significant that 53.9% of the patients could be followed up in this series. These observations are largely based on re-examination of patients, large number of whom most willingly returned for a follow-up check-up. Cooperation of Ophthalmologists, in distant states further augmented these records.
Certain changes during the follow-up period are now well known. The graft may get vascularised, 'Graft disease' may make the graft opaque, anterior synechia may damage the transparency, or a retro-corneal membrane may grow from the posterior graft margin. On the positive side, the tissue therapeutic effect .of lamellar graft on the deeper corneal opacity is well known. Changes in corneal curvature, corneal scars becoming markedly thin may make the visual results far more satisfactory than at the immediate post-operative period.
Naturally the disappointments first.
"Malaise du Greffons" continues to be the one single factor responsible for uncertainties in penetrating corneal grafts. This is an antigen-antibody reaction manifestation of tissue incompatibility, antigen being provided by donor graft and the antibodies being carried from the host by the blood cells. Tissue incompatibility invites vascularisation which in turn carries antibodies to the graft. Graft disease is therefore likely to be more frequent in bigger grafts the margins of which are close to the vascular limbus. A post-operative anterior synechia of the vascular iris tissue may be a further contributing factor. Unfortunately this tissue reaction cannot be predicted because there are no means to determine donor host incompatibility. Host immunisation with donor corneal extract may become theoretically possible but is impracticable because the same donor may not die when the recipient is being operated.
A severe anaphylactic tissue reaction may destroy the graft in first two post-operative days. This, fortunately is extremely rare, because the process of vascularisation is slow. The commonest time for the graft disease is about the end of third week, the critical period when the graft becomes more and more dependent on the host and the antibodies can readily reach the graft margin through the newly formed nutritional channels. Recurrence of graft disease is however a known possibility even upto 2-3 years after surgery. Delayed vascularisation, unsevered anterior synechia and attacks of sinusitis are known to precipitate attacks of 'Malaise-du-greffon'. During this reaction, graft becomes oedematous and opaque. The change is however reversible and adequate treatment of etiological factor combined with intensive local steroid therapy usually help in restoration of transparency.
A recurrent or persistant iridocyclitis can by itself be responsible for graft failure. Iridocyclitis may be flared up by an endogenous allergy to a septic focus or excited by a graft tissue reaction. Associated endothelialitis favours diffusion of fluid and oedema of graft. This may result in permanent dense opacification needing regrafting.
Proliferation at the healing posterior graft margin may result in formation of retrocorneal membrane called the `Rind'. This may lie in apposition with the posterior graft surface or may project into the anterior chamber or even get adherent to iris. A bigger graft is the only answer.
Rise of intra-ocular tension or repeated use of steroids may result in ectasia of the graft which introduces a high corneal astigmatism and seriously impairs the visual recovery while in cases of extensive anterior synechiae the graft may become staphylomatous and end up in a surgical tragedy.
Persistant Vascularisation and Blood Interface:
Persistant and recurrent vascularisation during the post-operative period is a significant hazard. In vascular corneas like those of chemical burns and complicated trachoma neovascularisation may invade the interface in lamellar grafts with vengeance and seriously jeopardise the transparency of the graft, or secondary adhesions may form between the graft margin and bulbar conjuctiva. There is a suggestion that in highly vascular corneas a keratectomy is to be preferred to lamellar grafting. In penetrating grafts moderate vascularisation usually stops short at the healing margin because newly formed blood vessels cannot easily penetrate through the fibrous ring. It is therefore again suggested that in chemical burns a penetrating graft may be better than lamellar surgery. Deep vascularisation arising either from the iris tissue or the deeper anterior ciliary vessels usually impairs the transparency of the graft. Blood interface in lamellar grafts tends to get absorbed and leaves behind no harmful effect. It may at times leave behind organised fibrous material thereby impairing the expected visual improvement.
One of the interesting effects of a lamellar graft is to help resolution of the deeper opacities in the host cornea. The donor tissue has a distinct therapeutic effect like any other tissue therapy. The process is usually slow and continues for a few months after surgery. On the basis of this practical and well established observation, lamellar surgery which though technically more difficult but many times safer should be practised oftener. If a lamellar graft of 0.4 to 0.5 mm. thickness can remove three fourths of the opaque corneal tissue, it should be the surgery of choice, provided of course the deeper opacity is not in the pupillary area. When surgery is planned for cosmetic reasons, lamellar keratoplasty in suitable cases will again serve the purpose adequately. These observations however do not apply to dense opacities with anterior synechia where the thickness of the cornea is uneven and there are chances of perforation of host tissue during dissection. Even if the anterior synechia is not deeply incarcerated in the cornea, the therapeutic effect will be negligible because the iris blood vessels will continue to keep on providing the fibroblasts.
Thinning of Scar:
The process of healing at the graft margin is again a continuing change for the better during the months after surgery. The density of the scar which might appear prominent at the time of discharge gets markedly thinner and may become even imperceptible in lamellar keratoplasty. Even in penetrating surgery, it often becomes fine enough not to be a cosmetic blemish. Anterior synechia to the graft margin again prevents this favourable change so that part of the scar may become markedly thin while the density of the scar may remain unchanged at the site of anterior synechia.
Assessment of Results during
Final assessment of visual recovery after corneal grafting can therefore only be made a few months after surgery. It is largely true that most grafts if they remain transparent upto third post-operative week, are likely to continue to remain so. The possibility of delayed 'graft disease', changes in corneal curvature, resolution of deeper corneal opacity, are factors which continue to alter the final picture of a corneal graft. A statement that a graft has taken well or the operation is perfectly successful made in first few post-operative days is misplaced and premature. A corneal surgeon should be prepared for unwanted disappointments and unexpected pleasures for quite some time after operation. The following table summarises the observations of the results of corneal grafting from the point of view of visual recovery.
Of the 111 patients followed during the period 1960 to end of 1964, good improvement continued to be maintained in 66 and in 23 a graft failure was still an unchanged consequence. Results remained unchanged in 74.5% in the penetrating series and in 85% of the lamellar. In 18 cases however a good immediate post-operative result was made distinctly poorer by late post-operative changes. The following case records are of interest, because although discharged with no visual improvement, during the follow-up period a change for the better was observes.[Table - 3]
| Summary|| |
Kiratoplasty is fraught with many experiences both pleasant and unpleasant.
Graft disease, uveitis, glaucoma persistent vascularisation of the graft, and blood interface in lamellar graft are consistant hazards.
However with the passage of time improvement takes place in some of the apparent failures.
Results in 111 cases over a follow- up period of four years, the grafts remained unchanged in 74.5% of cases (penerating graft)' and 85% of cases (lamellar graft). In 18 cases good immediate results were spoilt by late post-operative changes. Case notes of 5 cases are given in which improvement took place with the passage of time.
[Table - 1], [Table - 2], [Table - 3]
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