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   Table of Contents      
CASE REPORT
Year : 1997  |  Volume : 45  |  Issue : 2  |  Page : 116-117

Subretinal neovascularization associated with retinochoroidal coloboma


Department of Ophthalmology, Postgraduate Institute of Medical, Education and Research, Chandigarh

Correspondence Address:
V Gupta
Department of Ophthalmology, Postgraduate Institute of Medical, Education and Research, Chandigarh

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Source of Support: None, Conflict of Interest: None


PMID: 9475031

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How to cite this article:
Gupta V, Gupta A, Dogra M R. Subretinal neovascularization associated with retinochoroidal coloboma. Indian J Ophthalmol 1997;45:116-7

How to cite this URL:
Gupta V, Gupta A, Dogra M R. Subretinal neovascularization associated with retinochoroidal coloboma. Indian J Ophthalmol [serial online] 1997 [cited 2020 Aug 6];45:116-7. Available from: http://www.ijo.in/text.asp?1997/45/2/116/15005

Retinochoroidal colobomas are congenital abnormalities caused by incomplete closure of the embryonic fissure. Commonly associated complications include diminished visual acuity and retinal detachment.[1][2][3] Subretinal neovascularization (SRNV) is a rare complication of retinochoroidal coloboma with only isolated case reports in literature.[4][5][6] We report one such case of subretinal neovascularization in association with retinochoroidal coloboma.


  Case report Top


A 20 year old male presented with history of diminished vision in the right eye (RE) of 6 months duration and poor vision in left eye (LE) since last two years. On examination, the best corrected visual acuity was 6/36 in RE and intraocular pressure (IOP) was 18 mmHg. Examination of RE revealed an iris coloboma inferonasally associated with a large retinochoroidal coloboma inferiorly extending just below the fovea. There was no associated retinal detachment. Patient had no perception of light in LE and IOP was 12 mmHg. Examination of LE revealed an iris coloboma inferonasally with cataractous lens. Ultrasound B scan examination of posterior segment of LE revealed an inferior retinochoroidal coloboma with total retinal detachment. The patient was kept under 3 monthly follow up and instructed to report should blurred or distorted vision develop.

The patient was asymptomatic when he visited us six months later for routine examination. Fundus examination of RE revealed an area of serous detachment of about 3 disc diameter (DD) in size. Within this area of serous detachment, a typical dirty yellow membrane with exudates and haemorrhages suggestive of subretinal neovascularization was seen [Figure - 1]. Fundus fluorescein angiogram revealed an area of blocked fluorescence superotemporal to the fovea, corresponding to the haemorrhage seen clinically. The area of membrane showed an early hyperfluorescence which increased in the late phase and was located inferotemporal to and involving the fovea. The choroidal coloboma was seen inferiorly as a hypofluorescent area due to absence of background choroidal fluorescence [Figure - 2], [Figure - 3]. In view of the subfoveal location and large size laser photocoagulation of the membrane was not considered.


  Discussion Top


Subretinal neovascularization is a rarely reported complication of retinochoroidal coloboma.[4][5][6] Although there is no clue to the exact stimulus for its development in association with retinochoroidal coloboma, histologic studies do provide some insight. In retinochoroidal colobomas, there is an absence of choroicapillaries, Bruch's membrane and retinal pigment epithelium except at the border of the coloboma where retinal pigment epithelium is thickened and folded; retina is atrophic and the barrier function of Bruch's membrane is disrupted.[1],[6] Retinal detachment is known to occur in 40% of eyes with retinochoroidal coloboma and this may occur due to vitreous traction causing retinal breaks either outside the area of coloboma or in the anomalous retinal tissue within the coloboma.[1][2][3] The exact sequence of events that cause detachment are unknown, though it is assumed that liquefied vitreous gel permeates into subretinal space through defects in the anomalous retina within the coloboma[1]. A similar mechanism may also allow the choroicapillaries to enter the subretinal pigment epitnelial space, resulting in the development of subretinal neovascularization. Laser photocoagulation to the edge of the coloboma has been successfully used to create a choroiretinal adhesion surrounding the coloboma so as to prevent the communication with subretinal space, thus reducing the risk of retinal detachment.[1],[7] Similarly, it can be postulated that such a chorioretinal adhesion could also halt the development of subretinal neovascularization and we could have possibly prevented the development of SRNV in this patient, had we done the laser photocoagulation of the edge of the coloboma at the time of initial examination. Subretinal neovascularization which developed in our patient was large and subfoveal. Direct laser treatment of entire surface could have immediately destroyed the central vision[8] and hence was not offered. Also the perifoveal treatment of the SRNV as described by Coscas was not considered for couple reasons viz. i) the eyes included by Coscas for perifoveal treatment had a membrane that was less than 2.5 DD wide, while the membrane in our patient was approximately 3 DD in size and also ii) no patient in his study had any ocular disease other than macular degeneration that could account for the decreased visual acuity in the fellow eye.[9] In our patient, the size of membrane was larger than 2.5 DD and additionally the fellow eye was blind due to long standing retinaldetachment.

Subretinal neovascularization though rare, is definitely an important complication of retinochoroidal coloboma. We speculate that laser photocoagulation to the edge of coloboma may prevent the development of subretinal neovascularization by creating a firm chorioretinal adhesion and thus preventing the access of choriocapillaries to subretinal space. This must be kept in mind while managing these patients and also the patients should be instructed to report for examination should blurred or distorted vision develop, because timely laser photocoagulation can be successful in selected cases.[5],[6]

 
  References Top

1.
Michels RG, Wilkinson CP and Rice TA. Retinal Detachment. St. Louis : The C.V Mosby Company, 1990 PP 724-725.  Back to cited text no. 1
    
2.
Jesberg DO, Schepens CL. Retinal detachment associated with coloboma of the choroid. Arch Ophthalmol. 65:163-173, 1961.  Back to cited text no. 2
    
3.
Gopal L, Kini MM, Badrinath SS and Sharma T. Management of retinal detachment with choroidal coloboma. Ophthalmology 98:1622-1627, 1991.  Back to cited text no. 3
    
4.
Leff SR, Britton WA, Brown GC et al. Retinochoroidal coloboma associated with subretinal neovascularization. Retina. 5:154-156, 1985.  Back to cited text no. 4
    
5.
Steahly LP. Laser treatment of a subretinal neovascular membrane associated with retinochoroidal coloboma. Retina. 6:154-156, 1986.  Back to cited text no. 5
    
6.
Maberley AL, Gottner MJ and Antworth MV. Subretinal neovascularization associated with retinochoroidal colobomas. Can J Ophthalmol 24:172-174, 1989.  Back to cited text no. 6
    
7.
Sakai T. Three cases of retinal detachment associated with congenital coloboma of choroid. Folia ophthalmol Jap. 19:808, 1968.  Back to cited text no. 7
    
8.
Decker WL, Grabowski WM, Annesley WH. Krypton red laser photocoagulation of subretinal neovascular membranes located within the foveal avascular zone. Ophthalmology. 91:1582-1586, 1984.  Back to cited text no. 8
    
9.
Coscas G, Soubrane G, Ramahefasolo C and Fardeau C. Perifoveal laser treatment for subfoveal choroidal new vessels in age-related macular degeneration. Arch Ophthalmol. 109:1258-1265, 1991.  Back to cited text no. 9
    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3]



 

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