Scars and Opacities of the Cornea and Their Treatment file262 THE INDIAN MEDICAL GAZETTE [May, 1941 SCARS AND OPACITIES OF THE CORNEA AND THEIR TREATMENT By G. S. GUHA Honorary Ophthalmic

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262 THE INDIAN MEDICAL GAZETTE [May, 1941

SCARS AND OPACITIES OF THE CORNEA AND THEIR TREATMENT

By G. S. GUHA

Honorary Ophthalmic Surgeon, Government Hospital, Shillong

In our country, corneal soars and opacities are common. This is especially so in the crowded streets of big cities. The large majority of the partially blinded and a considerable pro- portion of the totally blinded are suffering from this ocular affection. The important causes of this group of ocular affections in our country are ophthalmia-neonatorum, neglected con-

junctivitis and corneal ulcers, smallpox, irritant drugs, trachoma, and keratomalacia. These scars and opacities may be due either

to the primary affection of the cornea itself

{e.g., primary ulcer of the cornea, perforating or penetrating injury, or injury to the cornea

by a foreign body or irritant drugs) or to its

secondary affection from the spread of an infec- tive or inflammatory process {e.g., neglected acute or chronic conjunctivitis, trachoma, glaucoma, scleritis, episcleritis, cyclitis, and

iridocyclitis), a growth from the other parts of the eye {e.g., pterygium), or the result of a

specific infective process of the system {e.g.,

syphilis, tuberculosis, leprosy, smallpox, chicken pox, cholera, and rarely influenza, cerebro-

spinal meningitis, malaria, and kala-azar), defi- ciency diseases {e.g., keratomalacia), senile and other degenerative conditions {e.g., arcus senilis, axial degeneration of the cornea, band-shaped opacity of the cornea, etc.), neurotrophic dis- orders {e.g., various forms of herpetic keratitis and lesion of the 5th nerve), or of the spread of certain skin conditions {e.g., rosacea, acne).

Again, such rare conditions as metabolic {e.g., keratitis in gout, sclerosing keratitis in diabetes, central indolent ulcer of the cornea in cachectic conditions in children) and endocrine {e.g., corneal grey spots in myxcedema) disorders, desiccation, exposure, and irritation {e.g., kera- titis sicca, keratitis lagophthalmos, in trichiasis, and ectropion of the lids, etc.), pigmentations of the cornea {e.g., metallic pigmentations of the cornea, melanosis of the cornea, and blood staining of the cornea), and congenital condi- tions {e.g., in congenital leucomata, congenital staphyloma, keratoconus and embryatoxis) may be the cause of corneal scars and opacities. Before going into the discussion of the treat-

ment of scars and opacities of the cornea,

some important facts about the structure and function of the cornea and its pathological variations should be borne in mind.

1. It is an avascular structure and its

nourishment depends mainly on dialysis from the periphery. Hence its metabolic process is

sluggish and its affection tends to be chronic. 2. Its function depends mainly on its trans-

parency and any slight injury to its tissue may affect this transparency.

3. The extreme sensibility of its epithelium and the imperviousness of its superficial cells to all toxins, except to the gonococcus and

diphtheria bacillus, and probably to the pneumo- coccus are its natural protections.

4. Its ̂ epithelium has wonderful powers of

regeneration. Therefore any damage of the

corneal tissue up to the limit of the epithelium is not of much consequence.

5. Its epithelium is continuous with the

epithelium of the conjunctiva; hence it is not difficult to see how the affection of the conjunc- tiva may also affect the cornea.

6. Its endothelium, like the external con-

tinuity of its epithelium with the conjunctiva, has also continuity with the uveal tract; there- fore an affection of the uveal tract may affect the cornea secondarily through its endothelium.

7. The sclerotic and the cornea are struc-

turally continuous with each other, both form- ing the external tunic of the eye; hence any

affection of the sclerotic may also spread to

the cornea.

8. The Bowman's membrane has little power of resistance and is easily affected. When once

destroyed, it never regenerates; therefore some

degree of permanent opacity is sure to result after it has been affected.

May, 1941] SCARS AND OPACITIES OF THE CORNEA: GUHA 263

9- The corneal lamella) in the substantia Propria when destroyed is not reformed, unless the defect is superficial, in which case the loss ?* tissue is replaced by epithelial growth.

10- Descemet's membrane, unlike Bowman's

jttembrane and the substantia propria, is a

ughly resistant structure. Therefore it is a great check to external infective processes Peering the eye.

11. In superficial injuries of the cornea, the detect is recovered by growth of the epithelium and no opacity of the cornea results.

12. When the injury of the cornea is deeper, ^generation of the epithelium together with the urination of new blood vessels from the peri- phery result in the growth' of connective tissue

_lch gives rise to corneal opacities or scars. 13. If the loss of corneal tissue is extensive

and scar tissue formation deficient, the thin cornea is likely to bulge out owing to the pres- ence of the intra-ocular pressure, resulting in an stasia of the cornea.

14. When the whole thickness of the cornea, ?Xcept Descemet's membrane is destroyed the atter, being very resistant, may still persist but u^ge forward as a result of intra-ocular pres-

Slll'e and thus form a keratocele. 15. In perforating wounds or in perforating

J?er of the cornea, if there is loss of aqueous, le iris may come in contact with the cornea

and slowly get attached to it by fibrinous exudate and thus form an anterior synechia

adherent leucoma. 16. In a perforating injury through the

centre c>f the cornea with the escape of aqueous and injury of the lens capsule, the lens capsule may form a synechia with the cornea.

I?- If any corneal scar is extensive, incar-

nated with the iris and ectasia, anterior aPhyloma is produced, which may be partial

?n. total, depending on the extent of the prolapsed ris tissue; when a part of the iris tissue gets ^tangled in the corneal perforation, a newly ?nned growth of the iris tissue may form in the

^ar tissue resulting in the pigment formation the adherent leucoma. 18. The entangled iris tissue in the perforated

i ea'. 0r the torn capsule of the lens in perforat- n? injuries may keep the opening partially

, ,Pen, so that the aqueous may slowly escape rough forming a fistula which looks like a ack dot on the cornea and which area is

1

ained by fluorescein. - 19- If the iris is carried not only into the ound but protrudes through it, the condition is ahed prolapse of the iris. 20. jn advanced cases of injuries to the

o?rnea, penetrating or otherwise, where the lens r

especially the vitreous may escape forming a ? opacity of the whole cornea, the condition

called phthisis bulbi anterior. Owing to

^ sudden lowering of tension in some other

^'ases, there may be choroidal haemorrhage, and _n.e vitreous, retina and choroid may come out

h the shrinkage of the whole eyeball, a con-

dition called the phthisis bulbi. Phthisis bulbi may also form as a result of cyclitis. Left to themselves, scars or opacities of the

cornea tend to clear up, especially in younger individuals and when the lesion is superficial, as already explained. Hence age is a great factor in regard to prognosis of vision after corneal affections. Besides having a tendency to clear up, such scars may give rise to pig- mentary or other degenerative changes. In extensive scar formation, glaucoma may result with associated degenerative changes in the

ciliary body, choroid, retina, and vitreous.

Treatment

1. Prophylactic or preventive (?) Mechanical protection of the eye by

goggles against accidental injuries of the cornea. (?) Vaccination against smallpox. (c) Introduction of vitamins in diet to pre-

vent keratomalacia.

(d) Prophylactic or preventive treatment for non-perforating wounds or ulcers against per- foration where the prognosis in regard to vision may be grave.

2. Medicinal

Medicinal treatment may be resorted to in more-or-less recent and superficial opacities of the cornea and where there is not much involve- ment of the neighbouring structures. Drugs used for the absorption of the corneal

Scars are mostly those which improve the local circulation. Such drugs are hydrargyri oxidum flavum, dionin, calomel, noviform, jequirity, quinine bisulphate, benzyl-cinnamic-ester, etc., instillation of oily drops, e.g., paroleine may be useful in keratitis sicca.

In addition to the local use of drugs non- specific protein therapy in the shape of milk

injections may give good results. Besides, specific therapy in syphilitic and

leprotic cases, as well as tuberculin in tuber- culous cases when not too late, may surprisingly clear up corneal opacities. Also local and in- ternal administration of vitamin A is useful in cases of keratomalacia and superficial punctate keratitis.

3. Physical Physical methods of treatment are used

with the idea of producing locally more lymph and peripherally more blood circulation; these

are finger massage, electric vibro massage,

ultra-violet ray, etc. The results of such methods of treatment are

very seldom satisfactory.

4. Operative treatment

Satisfactory results are mostly found by operative treatment.

(A) Optical iridectomy. In central and deep scars, where there is sufficient clear cornea left

at the periphery, optical iridectomy should be done.

264 THE INDIAN MEDICAL GAZETTE [May, 1941

The sites of election of this operation should be as shown in the following diagram :?

Optical iridec-

tomy should be as narrow as possible, so that the dazz-

ling effect of light is avoided and

stenopic vision ob- tained. It should not extend to the

ciliary border. (B) Thttooing of

the cornea. The reasons for tattoo-

ing of the cornea are two, viz, (i) optic, and (ii) cos- metic.

(i) A nebula may make vision more

.troublesome than a thicker opacity, e.g., macula or leucoma, owing to its dispersive action on

light. By tattooing, this dispersive action is

stopped and vision becomes more distinct. The

optical effect is seldom obtained by tattooing alone especially if the tattooed area covers a

large part of the pupillary aperture, unless later on an optical iridectomy is performed.

r (u) The cosmetic effect is obtained by tattoo- ing the thick opacities. If the thick opacity covers the greater part or the whole of the

cornea, the middle portion should be tattooed; the central area being thus made darker than the periphery; the pupil is simulated.

There are two methods of tattooing, viz, (i) # chemical, where the opaque cornea is dyed by chemicals, and (u) the introduction of

colouring agents directly into the corneal tissue. (i) Of the chemicals, various solutions have

been tried, e.g., gold chloride, platinum chloride, silver salts, iron sulphate and tannin. Of these, platinum is more suitable in our country because of its forming a dense black plaque with a

metallic lustre. The epithelium of the cornea is first scraped

off. The chemical solution is allowed to im-

pregnate the subjacent tissue over which the

epithelium again grows. (it) In the method of introduction of a colour-

ing pigment directly into the corneal tissue, lamp black, candle soot, ink or gold dust, have been tried.

Chemical agents give much better results. Corneal opacities may also be cleverly covered

by, coloured contact glass, the glass being coloured on the area covering the opacities.

(C) Keratoplasty or corneal grafting. This is the ideal operation for corneal scars, but, as it is an extremely difficult operation which should be done by experts only, we shall not give much space to its discussion. By grafting a clear cornea into the area from

where the scar has been removed, the whole cornea looks practically free from any opacity,

and if the result of the operation is successful there is consequently a considerable improve- ment of vision. Three methods of performing the operation

have been described, total keratoplasty, super- ficial lamellar keratoplasty, and penetrating circumscribed keratoplasty; of these the last- named operation gives the best result. In it a

small disc of the opaque cornea is removed with a trephine. A graft of the same size is similarly removed from the clear cornea of the eye of a

recently dead person or of a recently enucleated eye in which the cornea remains clear. The

graft is kept in place by a bridged double suture which extends over it from the conjunctival limbus on either side. In total keratoplasty, where the whole cornea

is transplanted, the after-results are very un-

satisfactory. Such a graft gradually becomes opaque and the iris gets adhered to it and either secondary glaucoma results or the eye is lost due to the formation of phthisis bulbi. This

operation has been given up now. In superficial lamellar keratoplasty, a cir-

cumscribed superficial lamella of an opaque cornea is removed and a lamella of transparent cornea is grafted on it. The remote results in

most cases are unsatisfactory. In Europe, both on the Continent and in

England, very good results have been obtained by keratoplasty. In our country too, similar results of this operation have been obtained by some eye surgeons (Kirwan, 1935).

Operative treatment of corneal scars with

complications

(a) In complete perforation of the cornea. (i) With prolapse of the iris tissue :?Free

excision of the prolapsed tissue should be done so that the formation of a staphyloma later on

may be prevented and if the wound gapes it

should be closed with a conjunctival flap or a

corneal suturing and pressure bandaging done. (ii) If a fistula forms without any prolapse

of iris tissue, repeated paracentesis should be

done to counteract the intra-ocular tension and

thereby help healing and then the wound should be closed with a conjunctival flap. If this fails? cauterization or scraping of the edges of the

fistula with a sharp knife, and then suturing the cornea or covering it by means of a conjunctival flap should be tried.

(b) In cases where a staphyloma develops. (i) When partial :?The adherent iris should

be cut with a knife through the anterior chamber or iridectomy may be done on either side of the incarcerated portion of the iris. ,

If the partial staphyloma be small, it should be split up with a knife and then excised witn forceps and then the divided portions sutured or covered by means of a conjunctival flap. #

(ii) When total and extensive, enucleation of the eyeball should be done.

(Continued at foot of opposite page)

IV

I' = the best. VI the worst (because the

coloboma is covered by the lid and is useless for vision).

Left eye.

I' = the best. VI = the worst (because the

coloboma is covered by the lid and is useless for vision).

(Continued from -previous -page)

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Axenfeld, T. (1935) .. Lehrbuch und Atlas der

Augenheilkunde. Gustav

n Fischer, Jena, p. 368.

JuKe-Elder, W.S.(1930). Brit. J. Ophthalmol., 14, 61, 185.

Idem (1938). Textbook of Ophthalmology. C. V. Mosby and Co., St. Louis, Vol. II, pp. 1282, 1283, 1826, 1828, 1950, 1952, IQfjQ 9fifl4 9035

{JmwAN, E. O'G. (1935). Indian Med. Gaz., 70, 61. Arsons, J. H. (1930) .. Diseases of the Eye.

Macmillan and Co., New York, pp. 234, 246.