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ORIGINAL ARTICLE
Year : 2006  |  Volume : 54  |  Issue : 2  |  Page : 85-88

Long-term anatomical and visual outcome of vitreous surgery for retinal detachment with choroidal coloboma


Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi - 110 029, India

Correspondence Address:
Raj Vardhan Azad
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0301-4738.25827

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  Abstract 

Context: Vitreous surgery has been advocated as an alternative treatment of selected retinal detachments with choroidal colobomas.
Aim:
To study the long term anatomical and visual outcome of choroidal coloboma with retinal detachment managed by pars plana vitrectomy with silicone oil tamponade.
Setting and Design: Retrospective study conducted in a tertiary eye care hospital.
Materials and Methods:
Fourty two eyes of 40 patients with retinal detachments related to coloboma of the choroid without any peripheral breaks were analyzed. All eyes underwent pars plana vitrectomy with internal tamponade using silicone oil. Endolaser was performed along the coloboma border. Silicone oil was removed in 50% of patients. The main outcome measures were retinal reattachment and visual recovery. SPSS (Statistical Package for the Social Science), version 10.0 was used for analysis.
Results: The retina in all cases (100%) undergoing vitrectomy were completely reattached intra-operatively. After a mean follow-up of 14 months, 37 (88.1%) eyes had attached retina. The best corrected visual acuity was 10/200 or better in 33 (78.4%) eyes. The best corrected visual acuity improved from a preoperative median of counting fingers (range 20/40 to perception of light) to median best corrected visual acuity of 20/200 (range 20/40 to perception of light) at the end of 6 months. Of the 50% (21) cases that underwent silicone oil removal, two eyes had re-detachment of retina.
Conclusion: Pars plana vitrectomy along with silicone oil tamponade for retinal detachment related to choroidal coloboma improves the long-term anatomical and visual outcome.

Keywords: Choroidal coloboma, pars plana vitrectomy, retinal detachment


How to cite this article:
Pal N, Azad RV, Sharma YR. Long-term anatomical and visual outcome of vitreous surgery for retinal detachment with choroidal coloboma. Indian J Ophthalmol 2006;54:85-8

How to cite this URL:
Pal N, Azad RV, Sharma YR. Long-term anatomical and visual outcome of vitreous surgery for retinal detachment with choroidal coloboma. Indian J Ophthalmol [serial online] 2006 [cited 2020 Jun 3];54:85-8. Available from: http://www.ijo.in/text.asp?2006/54/2/85/25827



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The choroidal coloboma is a congenital lesion characterized by the absence of normal retina, retinal pigment epithelium and choroid.[1],[2] This developmental anomaly is caused by the failure of closure of fetal fissure and is often associated with several other ocular anomalies, including iris coloboma, loss of inferior lens zonules, cataract and optic disk abnormalities. The prevalence of retinal detachment in eyes with choroidal coloboma has been reported to be from 8.1 to 42%.[2],[3],[4],[5],[6],[7],[8]

The use of conventional scleral buckling to treat retinal detachments in eyes with choroidal colobomas has resulted in low anatomic attachment rates of 35 to 55%.[3],[8]

Vitreous surgery has been advocated as an alternative treatment of selected retinal detachments with choroidal colobomas, but there are little data available on their long term anatomical and visual outcome. Silicone oil,[9],[10],[11],[12],[13] gas,[14] perfluoro-perhydrophenanthrene[15] and cyanoacrylate glue[13],[16] have been used as internal tamponading agents in these cases.

The aim of the present study was to evaluate long-term anatomical and functional outcome of choroidal coloboma with retinal detachment managed by vitreous surgery with silicone oil tamponade.


  Materials and Methods Top


Fourty two eyes of 40 consecutive patients who presented to the vitreo-retinal services of the hospital between January and December 2002 were included in this study. All patients had retinal detachment related to choroidal coloboma. The retinal detachment was attributed to the coloboma if there was extension of the detachment within the border of the coloboma and were included in the study. Patients with peripheral retinal breaks were treated with conventional scleral buckling surgery and were excluded. Though eyes with posterior holes or eyes with a rhegmatogenous retinal detachment in which no holes could be found were considered candidates for vitrectomy.

The review included the following demographic and ophthalmologic data: age, gender, date of coloboma diagnosis, date of retinal detachment diagnosis, best corrected visual acuity (BCVA), type and extent of retinal detachment, number and location of retinal breaks and location and extent of choroidal coloboma based on hospital medical records. The type of retinal detachment with associated choroidal coloboma was classified according to Gopal et al classification.[6] All patients were followed up and reviewed for best corrected Snellen visual acuity, anterior and posterior segment findings. Fundus drawings and color photographs were taken at each follow-up.

Surgical procedure

The protocol for the research project was approved by the Ethics Committee of our institution and it also conformed to the provisions of the Declaration of Helsinki 1995. The surgical management involved pars plana vitrectomy in all cases after informed consent. The lens was removed in 30 eyes (71.4%) due to existing cataract. Two patients had undergone conventional buckling procedure earlier with re-detachment and seven other patients received an encircling band during this procedure. Posterior vitreous detachment was absent in 25 patients (59.5%). Induction of posterior vitreous detachment when absent was initiated at the optic disc using suction followed by peeling with the forceps. In cases of proliferative vitreoretinopathy (PVR), membrane peeling was done. Peripheral encircling buckles were placed in cases with peripheral iatrogenic breaks produced during vitreous surgery (two cases) or severe grade PVR not having a preexisting buckle (five cases). A meticulous search for peripheral retinal breaks in the periphery and central retina was done with the use of wide angle viewing system (Oculus 130, Oculus Wetzlar, Germany). The colobomatous area and margin at this stage was carefully inspected under high magnification to locate the retinal breaks. Then, simultaneous air-fluid exchange and internal drainage was performed through the retinal break at the margin of or within, the choroidal coloboma. If this maneuver did not result in total retinal attachment, endodiathermy was performed to create another retinotomy, through which subretinal fluid was drained to totally reattach the retina. At least two rows of diode endolaser were applied along the margin of the coloboma. Prophylactic 360 degrees endolaser was also done in type IIe choroidal coloboma related retinal detachment cases. Cryotherapy was used for anterior margins of choroidal coloboma whenever laser was not possible. Internal tamponade was performed with silicone oil (1000 centistokes) in all eyes. In silicone oil filled aphakic eyes, inferior iridectomy was not needed in majority of cases because of the presence of coloboma of the iris. Patients were placed in prone position for one week postoperatively.

Silicone oil removal

Among the 42 eyes, 21 (50%) underwent silicone oil removal. The reasons for not removing the silicone oil included non-compliance of the patient (10), partial recurrent retinal detachment that was not amenable to further surgery (4) or re-operation (1) or patient not willing to undergo surgery again (6). The interval between silicone oil injection and removal ranged from 3 months to 24 months (mean = 4.2 months).

SPSS (Statistical Package for the Social Science), version 10.0 was used for analysis.


  Results Top


The demographic details as well as the patient's characteristics are depicted in [Table - 1]. The type of retinal detachment with choroidal coloboma was classified according to the classification of Gopal et al .[6] Type I detachments did not extend inside into the coloboma and were excluded from the present study. Type IIa was a subclinical detachment restricted to an area inside the coloboma and were asymptomatic. Type IIb had visible breaks within the coloboma without any peripheral break. Type IIc had visible breaks both within and outside the coloboma. Type IId was a rare theoretical possibility, wherein the detachment was caused by a peripheral break but the fluid had spilled into the coloboma. In Type IIe, any retinal break could not be localized either within or outside the coloboma even intra-operatively. The retinal detachment was total in 78.5% (33) and partial in 21.5% (9). Proliferative vitreoretinopathy was found in 21.4 % (9) cases and was severe grade D in 16.6% (7) cases, two of whom had undergone previous buckling procedures. Family history of coloboma was present in three cases. Nystagmus was present in 13 (31%) cases, iris coloboma in 41 (93.6%), microphthalmos in 6 (14.2%), microcornea in 8 (19.0%) and lenticular opacity in 30 (71.4%). The pre-operative BCVA ranged from 20/40 to perception of light (Median = counting fingers) with the presenting BCVA being less than 10/200 in 85.7% (35).

The retina in all cases (100%) undergoing vitrectomy was completely reattached intra-operatively. Drainage retinotomy was performed in nine cases where a break could not be localized intra-operatively. Recurrent retinal detachment occurred in 11.9% (5) of silicone oil filled eyes. The recurrence was caused by PVR in four cases (3 had pre-existing severe PVR D and one had PVR C/2) and a new break outside the coloboma in one case. Four cases with recurrent retinal detachment had type IIe choroidal coloboma and one case had type IIc choroidal coloboma. Revision surgery performed in one case involved removal of membranes under silicone oil in an eye with silicone oil and PVR and internal fluid drainage with endolaser around the break. Of the 50% (21) cases that underwent silicone oil removal, 10% (2) of eyes had re-detachment of retina. Both of these underwent further surgery with re-injection of silicone oil to reattach retina. The total follow-up was at least 6 months to 30 months (mean=14 months).Among the eyes that underwent silicone oil removal, the mean post-silicone oil removal follow-up was 12 months (range=6 months to 18 months). Six months after surgery, the retina was attached in 95.3% (40) eyes. After a mean follow-up of 14 months, 88.1% (37) of eyes had attached retina.

The BCVA was 10/200 or better in 78.4% (33) eyes at last follow-up [Table - 2]. The BCVA improved from a preoperative median of counting fingers (range 20/40 to perception of light) to final median BCVA of 20/200 (range 20/40 to perception of light) at the end of 6 months. 34 eyes (80.9%) gained more than or equal to two lines of BCVA while four eyes retained preoperative visual acuity and one eye had drop in visual acuity of one line. The postoperative complications included raised intraocular pressure in 5 (11.9%), hazy media in 7 (16.6%) and epithelial defect in 7 (16.6%) cases and were managed on medical treatment without necessitating early silicone oil removal.

The 23 eyes that had silicone oil upto last follow-up had no significant change in the BCVA at a follow-up of 3 months to 30 months (mean=14 months) with no major secondary oil related complications.


  Discussion Top


In the present study, primary outcomes (anatomical success, visual recovery) and secondary outcomes (complications) in 42 eyes (40 patients) with retinal detachment related to choroidal coloboma managed with vitrectomy and silicone oil tamponade were measured. The retina in all cases (100%) undergoing vitrectomy were completely reattached intra-operatively. After a mean follow-up of 14 months, 37 (88.1%) eyes had attached retina. The BCVA improved from a preoperative median of counting fingers (range 20/40 to perception of light) to median BCVA of 20/200 (range 20/40 to perception of light) at the end of 6 months.

The breaks that cause retinal detachments in colobomatous eyes are often hidden within the lesion and difficult to find with associated nystagmus and poor contrast due to absence of retinal pigment epithelium and choroid. Review of histological sections of eight choroidal colobomas showed central continuation of the inner neuroblastic layer (the intercalary membrane) and eversion and separation of the outer neuroblastic layer.[17] The subset of coloboma-associated retinal detachments require both a central break in the inner layer and a break in the outer layer at the margin of the coloboma.

Eyes with retinal breaks and retinal detachment outside the area of the coloboma are best treated with conventional scleral buckling techniques.[2] External buckling has a low success rate (35 -57%) due to difficulty in identifying breaks in the intercalary membrane, posterior location of the breaks and inability to create a surrounding chorioretinal adhesion using cryotherapy or laser photocoagulation.[3],[7],[8]

Pars plana vitrectomy has enabled the identification of the breaks in the intercalary membrane with more certainty and high success rate. Gas tamponade has been reported to have a low retinal tamponade and reattachment efficacy with three of five cases having a re-detachment in one series.[10] Cyanoacrylate glue retinopexy has been found to be useful, but is associated with significant problems. The flattening of the retina with endodrainage through the atrophic retina overlying the choroidal coloboma is often difficult to achieve and results in residual subretinal fluid preventing effective glue application.[13],[16] Silicone oil is considered to be the best tamponading agent that could tamponade the whole colobomatous border for a long enough time.[9],[10],[11],[12],[13] Diode laser is preferred to argon laser for treatment of the coloboma border as it is less likely to damage the nerve fiber layer due to deeper penetration taking care to avoid the papillomacular bundle. Better vitreoretinal microsurgical instrumentation and techniques and use of wide angle viewing systems as in the present study enable better anatomical and functional outcome.

The placement of encircling band in vitrectomy for choroidal coloboma has not been shown to have any difference in outcome from non-buckled eyes[10] and was done in the present study on a empirical basis in two patients who developed an iatrogenic peripheral break intra-operatively and five cases of severe grade PVR (two more cases had a pre-existing buckle with failed conventional buckling surgery). Posterior vitreous detachment was absent in 59.5% patients and it was considered important to separate the posterior vitreous from the retina to reduce the possibility of postoperative vitreous traction leading to recurrent detachment.

Recurrent retinal detachment occurred in 11.9% (5) of silicone oil filled eyes. The recurrence was caused by PVR in four cases (three had severe preexisting PVR) and a new break outside the coloboma in one case. The prevalence of PVR may be related to the young age of the patients and the chronicity of the detachment. The presence of type IIe choroidal coloboma in four of the cases with recurrent retinal detachment emphasizes the importance of break localization preoperative or intra-operatively.

Of the 50% (21) cases that underwent silicone oil removal, 10% (2) of eyes had re-detachment of the retina. Cautious removal has been advised in previous series with a re-detachment rate post silicone oil removal of 15.6[10] to 20%[13] and no removal was also considered in the present study in cases with partial recurrent retinal detachment that was not amenable to further surgery.

In the present series, the retinal reattachment rate of 95.3% eyes at six months after surgery and 88.1% after a mean follow-up of 14 months is comparable to other series of pars plana vitrectomy with silicone oil.[9],[10],[11],[12],[13] The BCVA improved from a preoperative median of counting fingers (range 20/40 to perception of light) to final median BCVA of 20/200 (range 20/40 to perception of light) at the end of 6 months. In the study by Hotta et al ,[16] the retina was successfully reattached by vitrectomy and cyanoacrylate retinopexy in four of the five eyes. In four eyes (80%), the vision showed improvement and had a visual acuity of 20/100 or better after surgery. In the study by Gopal et al,[10] 85 eyes of 81 patients with retinal detachments related to coloboma of the choroid underwent pars plana vitrectomy with internal tamponade using silicone oil (80 eyes) or perfluropropane gas (five eyes). Recurrent retinal detachment occurred in 16.3% of silicone oil-filled eyes and 60% of gas-filled eyes. After silicone oil removal, 15.6% of eyes had recurrent retinal detachment. After a mean follow-up of 13.4 months, 81.2% of eyes had attached retina and 69.4% recovered equal to or better than 10/200 visual acuity.[10] In the study by McDonald et al ,[12] all seven eyes with retinal detachments caused by retinal breaks at the margin of or within a choroidal coloboma reattached with pars plana vitrectomy and visual acuity in five (71%) of the seven eyes improved from preoperative levels. Hanneken et al[13] used vitreous surgery to treat seven patients (eight eyes) with complicated retinal detachments associated with choroidal colobomas. Adjunctive surgical techniques were necessary and included cyanoacrylate retinopexy in four eyes, silicone oil tamponade in five eyes and retinectomy in two eyes. Retinal reattachment was ultimately attained in seven of the eight eyes. The number of surgical procedures ranged from one to five, with an average of three. Post-operative visual acuity of the eyes that underwent anatomically successful procedures ranged from 20/100 to light perception. Proliferative vitreoretinopathy was the most frequent cause of re-detachment, occurring in six of the eight eyes.

In the present study, though vitrectomy is associated with post-operative complications including raised intraocular pressure (11%), hazy media (17%) and epithelial defect (17%), these were managed on medical treatment without necessitating early silicone oil removal.

The present study, besides adding to the limited data available on long-term functional and anatomical outcome of vitreous surgery in choroidal coloboma with retinal detachment also contributes knowledge about factors contributing to recurrent retinal detachment including pre-existing severe grade PVR and type IIe chorioretinal coloboma with no localized break. The limitations of the present study are that patients with silicone oil as a permanent tamponade and patients with silicone oil as a temporary tamponade were not analyzed separately and a detailed evaluation of structural and functional outcome in all sub-types of choroidal coloboma related retinal detachments were not done due to small sample size and in future, a larger subgroup of patients may be compared.

To conclude, complete vitrectomy with a method to create chorioretinal adhesion around the coloboma and silicone oil tamponade provides an effective treatment for this complicated type of retinal detachment with good long term anatomical and visual outcome.

 
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    Tables

  [Table - 1], [Table - 2]


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