A rare case of bilateral choroidal coloboma within deep posterior staphyloma associated with macular hole retinal detachment.

To report case of bilaterally symmetrical choroidal coloboma within posterior staphyloma with MHRD. This is a case report of a 50year old female presented with diminished vision in both eyes. On examination, she had Bilateral High Myopia with recent onset MHRD associated with symmetrically bilateral Choroidal Coloboma within posterior staphyloma and was operated for MHRD in left eye. Presence of choroidal coloboma within posterior staphyloma is rare and with coexisting macular hole makes pathophysiology of RD challenging to understand.

Myopic eyes are known to have a variety of abnormalities among which posterior staphyloma is one of the commonest. In this case report, we present a rare association of bilaterally symmetrical choroidal coloboma within the posterior staphyloma with macular hole retinal detachment.

In Asia, Europe, and some races in the United States, a major cause of visual impairment is high myopia.[12] Generally, high myopia is related to the axial extension of the eyeball, which can cause a variety of abnormalities in fundus, such as lacquer cracks in the Bruch membrane, posterior staphyloma, choroidal neovascularization (CNV), and chorioretinal atrophy.[34] Posterior staphyloma is associated with features of high myopia like myopic foveoschisis, macular hole retinal detachment, and few other conditions, whereas choroidal coloboma is a developmental disorder, widely believed to be related to the defective closure of embryonic fissure and is characterized by scleral ectasia with absence of overlying choroid and presence of defective retinal layers and intercalary membrane. This case report describes the presence of choroidal coloboma inside the staphyloma and also having MHRD.

Case Report

A 50-year-old healthy female came with a complaint of gradual painless diminution of vision associated with a floater in her left eye from the last one month. On examination, her visual acuity was found to be CF 3/4M Vision in the Left Eye and CF — M in the left eye. Anterior segment examination was unremarkable with intraocular pressure 19 mmHg in the right eye and 9 mmHg in the left eye. Fundus examination revealed myopic tessellated fundus with macular degeneration with the presence of an oval greyish lesion inferior to the macula within the deep posterior staphyloma symmetrically in both eyes [Fig. 1a and 2a]. The right eye also showed macular hole with retinal detachment. The left eye showed macular hole with Bullous Retinal Detachment extending from 11 to 7’o clock hr with choroidal detachment as evident on Bscan [Fig. 2a, b1, and b2].

Figure 1

(a) Colour photograph of the right eye showing Myopic Macular Degeneration with Chorioretinal Atrophy with grey oval lesion inferior to macula surrounded by the atrophy (yellow arrow). (b) OCT showing corresponding posterior staphyloma with deep excavation within it (yellow down arrow). (c) OCT showing corresponding macular hole with retinal detachment (yellow up arrow)

Figure 2

(a) Colour photograph of LE showing Myopic Degeneration with Retinal Detachment and Choroidal detachment with macular hole. (b1,2) Bscan showing choroidal detachment. (c) OCT showing the presence of MHRD preoperatively (red arrow). (d) Colour photograph showing attached retina postoperatively with greyish oval lesion inferior to macula (yellow slant arrow). (e) OCT showing deep excavation within it (yellow down arrow) and retina reattached over its contour postoperatively

A spectral domain OCT was performed and confirmed the presence of macular hole with retinal detachment in both eyes along with the presence of deep macular staphyloma [Fig. 2c]. Interestingly, deep within the base of the staphyloma on SD–OCT, there was further deep excavation within the staphyloma with thin RPE and choroid which was bilaterally symmetrical suggestive of choroidal coloboma [Figs. 1b, c, and 2c]. This coloboma was corresponding to the oval dark grey excavation seen clinically inferior to the macula and was found to be symmetrical in both eyes. She underwent Encirclage with Pars Plana Vitrectomy with Silicon oil injection. The ILM peel was not done in this case as the posterior staphyloma was too deep and could not be reached.

She improved to 6/36 in the left eye three months post-surgery with maintenance till the last follow up six months later. After surgery, the thin retina was seen to be completely reattached along its contour without any gap even over the colobomatous area [Fig. 2d and e]. There was no surgery done for the right eye as the patient complained of the visual loss from the last 30 yrs or so and was thus considered to be amblyopic and, hence, had nil visual prognosis.

Discussion

A posterior staphyloma is a hallmark of pathologic myopia,[5] and Spaide[6] defined it as an outpouching of the ocular wall whose radius of curvature is smaller than that of the surrounding ocular wall. Optical coherence tomography (OCT) analyses the scleral curvature in eyes with pathological myopia.[7] Choroidal coloboma with its myriad intricacies is another interesting condition for evaluation using this tool.[8]

The presence of choroidal coloboma within the posterior staphyloma is rare and with coexisting macular hole makes the pathophysiology of RD challenging to understand. After the surgery, the area of coloboma has completely reattached retina without any subretinal fluid similar to intercalary membrane (ICM), which is either detached or attached in patients with choroidal coloboma. The gap has been well apposed by the overlying retinal tissue despite the irregular contour and small gap. Also, MHRDs can settle and macular holes can close even without the ILM peel as in this case.

Conclusion

To our knowledge, this association has not been reported to date and adds to the complexity of understanding pathological myopia and management of retinal detachment in such complex eyes.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.