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|Year : 1979 | Volume
| Issue : 4 | Page : 126-128
System of evaluation of results in keratoplasty
G.R. Medical College, Jhansi, India
G.R. Medical College, Jhansi
|How to cite this article:|
Shukla B. System of evaluation of results in keratoplasty. Indian J Ophthalmol 1979;27:126-8
There has been a rapid advancement in the technique and instrumentation in keratoplasty in the last three decades. Many cases considered unsuitable for keratoplasty are being operated with reasonable hope of success. As there are many variables influencing the final outcome it is extremely difficult to compare results. However, it is important to have some common basis for evaluation of results. When variables are multiple no system is necessary to compare notes and understand the effect of variables. It is with this intention that a working system is evolved.
1. It may be said that keratoplasty is mainly done for optical and therapeutic purposes. With the advance in contact lens technique cosmetic keratoplasty is rarely done. Number of cases requiring tectonic or refractive keratoplasty is also very small.
2. Then the lamellar and penetrating types of keratoplasties though appear similar in operative procedure are in reality radically different. In one the delicate endothelial lining is undisturbed whereas, in another it is replaced by a relatively uncertain mechanism. Hence the two types require separate analysis.
3. A very important factor is the type of case selected for operation. Castroviejo has classified the recipients in six major groups from favourable to completely unfavourable in order to assess the prognosis.
4. The quality (viability) of donor material is also an important factor in the success of a corneal grafting.
The author has worked out the prognosis index of keratoplasty on the basis of viability and suitability indices.
5. Another variable is the time of assessment (follow-up). One month is minimum, one year desirable and five years ideal. It is desirable to mention the assess. ment time and group cases accordingly. Again, the visual acuity has to be noted with naked eye and with optical aids after the operation.
In optical keratoplasty the aim is to improve the vision and hence the degree of improvement of visual acuity will be the index of success. Dhanda has rightly pointed out that final vision is not so important as the difference between post-operative and pre-operative vision and has given a percentage equivalent table. The present tables have been made on a similar basis with some modifications. Vision from P.L. to 6/60 is graded in steps of 5% [Table - 2] and vision from 6/60 to 6/5 is graded in steps of 10% [Table - 3]. Perception of light (P.L.) or hand movement (H.M.) is graded as 0% (though theoretically only, no P.L. should be 0%) vision of 6/60 as 40% and vision of 6/6 as 100% with intermediate grades. Vision of 6/5 is graded as 110%. In [Table - 2] with vision upto 6/60 a change upto 5% is not considered whereas in [Table - 3] a change upto 10% is not considered as an improvement or deterioration.
In optical keratoplasty improvement of vision is the primary factor. In therapeutic keratoplasty removal of diseased tissue is primary and incidental improvement of vision secondary. Hence a basic 30% is added irrespective of improvement in visual acuity provided the diseased tissue is removed. Here again, lesions not involving the papillary area should not be considered. Due to paucity of cases this analysis has not been done in the present paper.
In analysing 160 cases in the present work, good prognosis group includes cases with prognosis index 60% or above and the rest are in bad prognosis group. However, for sake the of simplicity these groups can be classified in combinations of good. fair and poor. The results can be presented in various ways stressing any one of the variables primarily e.g. type (P.K. or L.K.), prognosis (good or bad) nature (optical or therapeutic), assessment time (1 month or 1 year) and effect of optical aids (glasses or contact lenses). The final improvement is the difference between maximum vision with optical aids minus initial vision. [Table - 1] gives the expected clarity of graft with time. It may be pointed out that lamellar grafts usually show improvement with passage of time, whereas penetrating grafts discharged with apparent clarity may turn hazy at variable interval due to immune reaction.
| Observations|| |
160 consecutive cases of keratoplasty have been analysed. [Table - 2] shows the distribution of cases and [Table - 3] the percentage of success in each group. The low incidence of success in penetrating keratoplasty (30%) is because 60% of cases were belonging to unfavourable group. Many of these cases were one eyed and keratoplasty though not indicated was done on mercy grounds and one cannot be hopeful in this procedure (Dhanda). Even in favourable group the success rate is only 55% which is not high. Nonavailability of ideal donor material and prevascularisation of the cornea may account for it to some extent. Though the results in favourable group of lameller keratoplasty are equally bad (14%), the results in the favourable group is satisfactory (75%).
In 66 cases where there was some improvement in vision, the results were further analysed to assess the degree of improvement. [Table - 4] shows the degree of improvement in 34 cases of penetrating keratoplasty and [Table - 5] in 32 cases of lameller keratoplasty. The average improvement is nearly equal in both cases (26-27%).
In [Table - 6] the results of successful keratoplasty is further analysed in both groups. In most cases improvement was 11 to 20% (22 cases). In only 3 cases improvement was over 60%. None of the patients in this series got contact lenses and so the degree of improvement in the present series will go further high. [Table 7] shows the follow up period.
| Comments|| |
It is not easy to define a fully successful graft. Bron has tried to define it as `one which is optically clear on biomicroscopy and gives excellent visual acuity; has a regular anterior curvature with minimal astigmatism, an endothelium with a normal cell density and with normal pumping and barrier functions and following from this, a fully deturgesced stroma, This definition though ideal is unpractical for most clinicians and various grades of success have to be recognised in different situation.
Leigh has stated the results of leading corneal surgeons including his own series of 100 cases. The results are classified as precentage of improved, no better and worse. There is no reference as to the type of cases and the degree of improvement. The results of the cases analysed is fairly low whatever the reasons may be. However, what is important is the method of analysis of results which, if accepted by others, can form a common platform for corneal surgeons to speak and understand each other in more clear terms.
| References|| |
|1.||Bron, A., 1973, Corneal Graft Failure, Ciba Foundation Symposium. Associated Scientific Publishers, London, 339. |
|2.||Castroviejo, R., 1966, Atlas of keratectomy and keratoplasty W.B. Saunders Co., Philadelphia, 404. |
|3.||Dhanda, R.P. and Kalevar, V. 1972, International Ophthal. Clinic, 12, No. 3 & 4, 351. |
|4.||Dhanda, R.P. and Kalevar, V. 1972, International Ophthal. Clinic, 12, No. 3 & 4, 354. |
|5.||Leigh A.G., 1966, Corneal Transplantation, 1 st Ed. Blackwell Scientific Publications, oxford, 308. |
|6.||Rice, N.S.C., 1974, Trans. Ophthal. Soc., U.K., 94, 94. |
|7.||Shukla, B., 1975, Proceedings of All India Ophthal. Soc., 120. |
|8.||Shukla, B. 1976, Proceedings of the VI Afro. Asian Congress of Ophthalmology, Madras (under publication) |
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6]