|Year : 1964 | Volume
| Issue : 2 | Page : 85-90
Corneal grafting in vascularised cornea particularly in trachomatous eyes
RP Dhanda, VK Kalevar
Corneal Surgery Unit and the Regional Eye-Bank, Indore, India
|Date of Web Publication||14-Feb-2008|
R P Dhanda
Corneal Surgery Unit and the Regional Eye-Bank, Indore
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dhanda R P, Kalevar V K. Corneal grafting in vascularised cornea particularly in trachomatous eyes. Indian J Ophthalmol 1964;12:85-90
Trachoma by virtue of being associated with vascular changes in and round the cornea has long been considered a disadvantage for keratoplasty in trachomatous circumstances. The observations made here are from a series of corneal grafts on 86 trachomatous recepients out of a total of 240 operations on 216 eyes.
From the reports of the recent national survey for the incidence of trachoma it has been established that trachoma directly or indirectly is the one biggest single cause responsible for the heavy incidence of corneal blindness in India specially in children.
Madhya Pradesh with an incidence of 41.3%, has Trachoma as a problem of significance.
In a series of 500 cases referred for keratoplasty, 214 (42.8%) had trachoma of which 27.1% were in active stage, 55.1 % in healed and 17.8% in complicated stage. Similarly, of the 216 operated eyes (24 being retransplants)), 86 (39.8%) had trachoma of which 27.9% were in active stage, 51.2% in healed and 20.9% in complicated stage. This series is therefore fairly representative of trachomatous circumstances and of the practice of corneal grafting in vascularised corneas.
Corneal vascularisation, we all know can be of non-trachomatous or trachomatous etiology. 98 out of 216 eyes operated in this series, 45.4%, had distinct vascularisation of the recepient cornea, 45.9% of which being of trachomatous origin. The remaining 54.1 % included 11 cases of chemical burns and 16 cases of long standing degenerate conditions like total leucoma adherens, partial and total anterior staphylomata.
This corneal pathology associated with vascularisation is further complicated in some cases by secondary changes in the conjunctival and the corneal epithelium like xerosis, symblepharon etc., thereby becoming an important consideration in the assessment of indications and prognosis of corneal grafting.
Vascularisation has a disadvantage that the blood vessels carry large doses of antibodies to the otherwise avascular donor corneal grafts and therefore add to the incidence of graft disease. This factor is further supported by the greater incidence of graft failures with postoperative anterior synechia not because the anterior synechia clouds the graft but the vascularity of the uveal tissue provides the antibody material.-Maumanee (1962).
Vascularisation of the cornea has another important consideration in corneal surgery. Blood vessels have a tendency to readily extend in-between the recepient cornea and the lamellar graft thereby laying down fibrous element and impairing vision. It is interesting to note that a full thickness graft resists invasion by vessels which may at the most extend upto and along its margin without affecting its clarity. They may rarely extend, on to the posterior surface. The suggestion therefore is that for vascular corneas, a penetrating graft with recession of conjunctiva or pseudo-pterygium and diathermy of blood vessels at the time of operation should be the choice as primary surgery (Hughes). Any vessels which reappear after the operation are usually small and being new can be successfully treated by β-radiation. Some suggest, small vascularisation may even be desirable. De Voe (1963)
| Histo-Pathological Studies of Trachomatous and Vascular Corneas|| |
Diseased corneas removed from recepient eyes provided an interesting material for histo-pathological studies.
From an intial study of over a 100 corneal buttons some interesting observations on trachomatous and vascular corneas are being reported.
Hyper- and parakeratosis, epithelial dysplasia and hyper-plasia in trachomatous corneas with secondary xerosis have been characteristically noted. A droplet type degenerative change observed in lamellar layers of the corneas of complicated trachoma has been a very interesting observation and awaits further analysis.
Alkalies like ammonia and caustic soda, sulphuric acid, sulphur dioxide and garlic were responsible for gross and vascular pathology in cornea in 12 cases for which corneal surgery was done. These corneal buttons have provided another group of interesting histo-pathological findings. Marked hyperplasia and newly formed superficial and deep vascular channels adequately confirm the extremely poor prognosis of keratoplasty in chemical burns, also reported in literature-Hughes (1963).
Following are a few of the characteristic histopathological findings:-
| Pre-Operative and Operative Considerations|| |
Apart from specific local anti-trachoma therapy for three weeks in active cases, in every case of vascularisation of some degree, a real deep peritomy preferably a week before grafting is an essential pre-requisite. Bigger blood vessels on the sclera are cauterised and smaller ones near the limbus treated with Hildreth. Thio-Tepa, (Cynamide) has been suggested as an effective drug for control of vascularisation by virtue of its property of inhibiting proliferation of endothelial cells and thereby preventing new capillary formation.Rock (1963).
Friability of the trachomatous and vascularised corneas is an important factor, particularly during lamellar dissection and stitching of the graft. In a thin dissection of 0.3 mm. or less, there is a tendency for tearing of the recepient corneal button. The depth of dissection in such cases should therefore not be less than 0.4 to 0.5 mm. to reduce chances of buttonholing. A trachomatous cornea is relatively thicker unless it is associated with corneal ectasia in which cases of course the choice is penetrating surgery and not lamellar grafting. The bite in the tissue while stitching the graft, however, should be relatively deeper to prevent cutting through the friable superficial lamellae of a vascular cornea.
Evidence of trachomatous scarring should be pointedly looked for in the donor eyes also. The eye in a dead body having become avascular, it is not always easy to identify trachomatous pathology except in grossly scarred lids. Herbert's pits and corneal haze extending intralimbal can however be seen in proper illumination even in an enucleated eye. This scarred area should therefore be specifically excluded from the donor button.
| Post-Operative Complications|| |
An analysis of the post-operative complications in trachomatous and non-trachomatous series is interesting. Of the 140 penetrating grafts 49 were on trachomatous eyes and 91 on nontrachomatous eyes. The significant difference in the markedly higher incidence of ectasia in trachomatous cases is due to premature falling off of stitches which is more frequent in soft friable vascular corneas.
In the lamellar series, a markedly higher incidence of ulcer complication is again distinctly due to trachomatous pathology. Vascularisation, as expected, is relatively more frequent both in penetrating and lamellar surgery.
Ectasia, vascularisation and ulcers therefore, could be considered postoperative complications directly related to trachomatocs pathology in the recepient eye.
Epithelial ulcer is an intractable complication and because of deficient metabolic state of the graft, takes a long time to heal. Superficial vascularisation usually readily responds to therapy, but in complicated trachoma and heavily vascularised corneas of chemical burns however, although the graft in early stages appears clear, fleshy vascularised tissue may invade it later on and ruin the chances of recovery.
| Results|| |
With all that has been said above, it should be natural to compare the final results of corneal grafting in trachomatous and non-trachomatous cases.
From a study of this table it may be noted that results of surgery in nontrachomatous cases and in cases associated with trachoma in stages I-IV are not appreciably different but complicated trachoma is however a different problem. The successful results in lamellar surgery from 88.9% in nontrachomatous and 73.4% in trachomatous (I-IV) eyes are markedly reduced to 43.7%, in complicated trachoma. Penetrating surgery is of course not to be attempted in eyes grossly complicated by trachoma.
It should be correct to infer therefore that except in complicated stage, trachoma is a consideration but not a contraindication for corneal grafting in India.
The two complications peculiar of corneal surgery in trachoma are:
1) premature falling of stitches, with a consequent higher incidence of ectasia,
2) a higher incidence of ulcers in the lamellar series.
| Acknowledgement|| |
We are grateful to the Indian Council of Medical Research and the National Council to Combat Blindness Inc., New York for their substantial help to enable us to undertake newer aspects of study and research.
Dr. M. M. Arora, Professor of Pathology, M. G. M. Medical College, Indore and Dr. D. N. Gupta, Professor of Pathology, Maulana Azad Medical College, New Delhi have given valuable guidance in histo-pathological studies. We are thankful to Dr. U. C. Gupta, Director, T.C.P.P. for providing useful data.
| References|| |
DeVoe, A. G. (1963) Arch. Ophth. 70: 737-738 (Editorial).
Dhanda, R. P. (1963) Amer. J. Ophth. 55: 1217-1219.
Hughes, W.F. (1963) Trans. Am. Acad. Ophthal. & Ots. 67: 292-319.
Maumenee, A. E. (1962) Personal communication.
Rock, R. L. (1963) Arch. Ophth. 69: 330-334.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]
[Table - 1], [Table - 2]