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   Table of Contents      
ARTICLE
Year : 1970  |  Volume : 18  |  Issue : 2  |  Page : 41-44

Oxygen in corneal vascularisation


Department of Ophthalmology, Sawai Man Singh Medical College, Jaipur, India

Correspondence Address:
H N Chhabra
Department of Ophthalmology, Sawai Man Singh Medical College, Jaipur
India
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Source of Support: None, Conflict of Interest: None


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How to cite this article:
Chhabra H N, Consul B N. Oxygen in corneal vascularisation. Indian J Ophthalmol 1970;18:41-4

How to cite this URL:
Chhabra H N, Consul B N. Oxygen in corneal vascularisation. Indian J Ophthalmol [serial online] 1970 [cited 2019 Dec 6];18:41-4. Available from: http://www.ijo.in/text.asp?1970/18/2/41/35060

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Corneal vascularisation accounts for a number of failures in corneal surgery. In our country where trachoma is the principal aetiological factor in 80% sof these cases, the problem gains obvious irnportance. There has been world­wide search for means to reduce cor­neal vascularisation before and after keratoplasty. The use of local steroids, antimitotic drugs and beta radiations have all got a definite role and limita­tions. Some of these are not available to all the ophthalmic centres.

If we go into the cause of neovascu­larisation in ocular tissues, there has been tremendous work on its genesis in retina. Michaelson (1948) showed a capillary free zone around normal arterioles in the retina whereas such a zone is absent around the venules. This has been attributed to higher oxygen tension of the arteriolar blood. Obser­vations on experimental animals have also shown that the oxygen concentra­tion of circulating blood has calculable effect on the patency and growth of not only the growing retinal vessels (Ashton, 1961; Agrawal, 1966), but also on the retinal vessels of mature retinae (Agrarwal, 1967). In many dis­eases anoxia has been held responsible for characteristic development of new vessels such as Eale's disease, diabetic retinopathy, central vein occlusion and retrolental fibroplasia.

There have been variable explana­tions regarding vascularisation of the cornea. Anoxia has been considered to be an important factor (Adler, 1965). Corneal vascularisation in acne rosacea or riboflavin deficiency has been attributed to deficient oxygen supply to the cornea (Johnson and Eckhardt, 1940). Much less attention however, has been devoted to the pro­blem at basic physiological level. Never the less if we explore the problem with an analogy from the behaviour of re­tinal vessels to varying concentrations and pressures of oxygen, the solution to the problem of corneal vascularisa­tion may not be as intriguing as it is today.

With this back ground and facing the lack of other means to fight cor­neal vascularisation we planed to try oxygen therapy as a means to reduce corneal vascularisation.


  Material and Methods Top


20 patients of vascularised corneal opacities due to a variety of causes were subjected to oxygen therapy. Some of these cases attended as out door patients while the rest were ob­tained from the Eye wards of the S. M. S. Hospital Jaipur. With proper history and thorough ocular examina­tion all the cases were classified accord­ing to the aetiology of their corneal conditions. Slit lamp examination was done in all the cases to map out the number, position and depth of the ves­sels in each case.


  Technique of Oxygen Injection Top


2 drops of 1 % anethane and a drop of 1: 1000 adrenaline were instilled into the conjunctival sac. 100% oxygen was obtained in a 2 cc glass syringe through a sterile rubber catheter attached to an oxygen cylinder. Eye speculum was inserted and the con­junctiva pinched with a toothed for­ceps, close to the limbus where the corneal vessels crossed it. 1.5 to 2 cc of oxygen was injected under the conjunctiva with a 26 gauge needle. In cases showing multiple vessels the given quantity of oxygen was injected at 2 spots or more. The eye was light­ly padded and bandaged for 3 to 4 hours. As per requirement the oxy­gen injection was repeated on alternate days or twice weekly to a total of 4 to 6 injections.

The eyes were examined daily under the slit lamp microscope to record the progress of the case. The results were graded as follows:­

(a) Good: when the invading cor­neal vessels disappeared in toto.

(b) Fair: when atleast half the number of vessels collapsed.

(c) Poor: when less than half the number of vessels were affected.

In the cases taken up for kerato­plasty, oxygen therapy if required was started as soon as a vessel appeared close to the graft edge. All the cases were followed up for a period from 4 to 5 weeks.


  Observations Top


The oxygen thus introduced under the conjunctiva spread uniformly under it and lifted the whole conjunctiva over and around the site of injection. Seen under slit-lamp, the oxygen appeared to break into bubbles of varying sizes. The oxygen around the limbus was the earliest to disappear (6-8 hrs.) while that in the fornices absorbed completely in 24 to 48 hours. The whole procedure was extremely well tolerated except that a dull pain was experienced by a small number of cases. In three cases there was loca­lised leak of blood under the conjunc­tiva which cleared in 4 to 5 days time. The subsequent injections however were not withheld in these cases.

[Table - 1] shows the type of cases sub­jected to oxygen therapy by this pro­cedure.

It may be noticed that the response varied with the size and the depth of the vessels and the duration of the opacity.

(a) Superficial vessels

(i) In recent opacities as small superficial vessels disappeared with 4 to 5 injections. The bigger vessels however showed only some narrowing of the lumen which was not maintain­ed.

(ii) Among the older vessels small capillary type did show com­plete obliteration which could not be maintained due to the unaffected medium sized and big vessels, which they joined.

(b) Deeper vessels

Whether recent or old, the ves­sels much deeper to Bowman's membrane did not show any appreciable change even after repeated oxygenation, except probably in cases following keratoplasty where the res­ponse was comperatively fa­vourable inspite of depth.

As to the duration of effectivity by this procedure it was noticed that prac­tically all the cases which responded, showed lasting effect. The failures were due to the persistence of the unaffected bigger vessels. It may how­ever be admitted that the follow up in these cases has been rather small.


  Comments Top


The obliteration of small conjunc­tival vessels by oxygen appears to be fairly comparable to that observed by the earlier workers (Ashton and Ped­ler, and Agrawal, 1966) in the ani­mal retinae. The earliest discernible change in the lumen appears within half an hour of the injection and is maintained by the continued presence of oxygen by the subsequent inject­tions. As suggested by these workers the endothelial cells are in someway sensitive to oxygen and undergo de­generative changes so as to lead to obliteration of the lumen. The latter assumes a permanent character if the oxygen concentration be continuously maintained for 8 to 12 days. The big­ger vessels are probably less vulnerable due to the well formed vessel wall in addition to the endothelium. The deeper vessels are probably not accesi­ble tc the required concentration of oxygen. The newly formed vessels have presumably a more delicate endo­thelium and thus more amenable.

Oxygen therapy therefore, offers promising field in the fight against cor­neal vascularisation as a primary procedure or in conjunction with the sur­gical procedure such as peritomy, peri. tectomy etc., where the old vessels can be converted to new, atleast in part of their course and thus made more vul­nerable to oxygen[7].

 
  References Top

1.
Alder, F.H.; Physiology of the eye. The C.V. Mosby & Co., St. Louis. 1963.  Back to cited text no. 1
    
2.
Agrawal, P.K., Agarwal L.P. and Tandan H.D., Oxygen and retinal Blood Vessels; Orient. Arch. Opht. 4, 77 (1966).  Back to cited text no. 2
    
3.
"do": Personal Communication (1967).   Back to cited text no. 3
    
4.
Ashton, N.: Neovascularization In Ocular Disease; Trans. Opht. Soc.; UK. Vol. LXXXI, 145-161. (1961).  Back to cited text no. 4
    
5.
Ashton, N. and Pedler, C., Studies on developing retinal vessels IX Reaction of Endothelial cells to Oxygen, Brit. J. Opth. 46, 257-276 (1962).  Back to cited text no. 5
    
6.
Jhonson, L. and Eckhardt. R.; Rosacea Keratitis and Conditions with Vasculari­zation treated with Riboflavin.; A.M.A. Arch. Ophth. (Chicago) 23, 899.  Back to cited text no. 6
    
7.
Michaelson, I. C.; The Mode of Deve­lopment of the Vascular System of the Retina, with some Observations on its Significance for certain retinal diseases.; Trans. Opht. Soc. U.K., 68, 137. (1948)  Back to cited text no. 7
    



 
 
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