A rare case of focal choroidal excavation associated choroidal neovascularization in angioid streaks.

The purpose is to report a case of focal choroidal excavation (FCE) in a patient with angioid streaks (ASs) associated with secondary choroidal neovascularization (CNV). A 26-year-old man was referred for the treatment of CNV. On further evaluation, he was found to have ASs and optical coherence tomography revealed the presence of the choroidal neovascular complex associated with FCE. The patient was treated with a single dose of intravitreal bevacizumab (1.25 μg/0.05 ml). There was resolution of the lesion, and on further follow-up over 6 months, there were no recurrences. CNV in patients with ASs may also be associated with FCE. These patients have a good response to intravitreal antivascular endothelial growth factor injection. Copyright:

Introduction

Angioid streaks (ASs) or Knapp's striae were first described by Doyne in 1889 as irregular radiating lines extending from the disc to the periphery. Histopathology revealed them to be weak areas in the Bruch's membrane with abnormal calcium deposits. They cause no visual symptoms until associated with secondary choroidal neovascularization (CNV). In patients with AS, the incidence of secondary CNV ranges from 72% to 86%.[1] Focal choroidal excavation (FCE) is a recently recognized entity detected on optical coherence tomography (OCT), first described by Jampol et al.[2] It is characterized by a localized area of excavation of the choroid, without evidence of a posterior staphyloma or scleral ectasia. The presence and association of FCE and wet age-related macular degeneration and CNV (AMD-CNV) have been well documented.[3] FCE has also been reported to be associated with central serous chorioretinopathy (CSC)[4] and polypoidal choroidal vasculopathy.[5]

This case illustrates a heretofore unreported association of FCE and CNV secondary to AS.

Case Report

A 26-year-old male was referred with complaints of defective vision in the left eye since 20 days. There was no history of associated trauma. His best-corrected visual acuity (BCVA) was 6/6 right eye (RE) and 6/12 left eye (LE). Anterior segment and intraocular pressure were normal in both eyes (BE). Fundus BE showed hyperpigmented lines radiating from the disc, suggestive of ASs. In addition, LE macula showed subretinal hemorrhage with subretinal fluid, suggestive of CNV. OCT RE was within normal limits and LE showed a hyperreflective lesion above the retinal pigment epithelium (RPE) with associated subretinal fluid in juxta foveal area. RPE-choroidal layer showed a focal excavation with the hyperreflective lesion on its slope as shown in Figure 1. Fundus fluorescein angiography (FFA) was done elsewhere before the referral and hence could not be repeated on presentation. However, the posttreatment FFA confirms the ASs as well as the presence of CNV corresponding to the area of FCE [Figure 2]. LE was treated with intravitreal bevacizumab injection (1.25 μg in 0.05 ml). At the 1 month follow-up visit, OCT showed resolved subretinal fluid and hemorrhage and a scarred choroidal neovascular membrane (CNVM) was noted within the slope of the FCE as shown in Figure 2. The patient was further followed up for 6 months, with no signs of recurrence and having a stable BCVA of 6/9.

Figure 1

(a) Color fundus picture of left eye showing angioid streaks, macular area showing hemorrhage and choroidal neovascular membrane. (b) Optical coherence tomography showing choroidal neovascular membrane and focal choroidal excavation

Figure 2

(a) Fundus fluorescence angiogram highlighting the angioid streaks and scarred choroidal neovascular membrane. (b) Optical coherence tomography showing inactive choroidal neovascular membrane along the slope of the focal choroidal excavation

Discussion

CNV is a common complication associated with ASs. It has been proposed to occur due to weakness and dehiscence of the Bruch's membrane which allows the CNV to grow through the cracks in the Bruch's membrane. Many treatment modalities including laser photocoagulation,[6] photodynamic therapy,[7] transpupillary thermotherapy,[8] feeder vessel occlusion, and surgical removal of the CNV or macular translocation have been tried, but all have a poor visual prognosis on long-term follow-up. Intravitreal anti-vascular endothelial growth factor (VEGF) has also been tried, and the results are encouraging. Iacono et al. followed up nonsubfoveal CNV in AS patients treated with intravitreal bevacizumab for 3 years and found a statistically significant BCVA worsening registered at the 24 and 36 months.[1] Recurrences and bilateral involvement contributed to the poor results. However, the treatment follow-up of our patient with FCE and CNVM showed a good response to a single dose of intravitreal bevacizumab and no recurrence was noted over a period of 6 months.

FCE was initially thought to be a stable lesion which occurred as a result of outward traction on the macula due to abnormal vascular development, resulting from an embryonic developmental failure of the choroid. Ellabban et al. proposed FCE to occur as a result of RPE retraction that occurs due to scarring of focal choroidal tissue,[4] implying that it could be an acquired disorder associated with conditions such as CSC.

FCE was further divided into conforming and nonconforming types. In conforming FCE, all the retinal layers followed the choroidal excavation. In nonconforming type of FCE, there is a separation between the RPE and the photoreceptor tips.

FCE is associated with AMD-CNV; the probable mechanism for its occurrence was proposed by Margolis et al. that FCE affects the structure of the RPE and the underlying choroid, which results in choroidal ischemia and CNVM.[9] Some authors have hypothesized that the space between the photoreceptor complex and RPE in nonconforming type of FCE may allow ingrowth of AMD-CNV. In our case, the patient has ASs, which is charecterised by abnormally brittle bruchs membrane. Along with that the presence of FCE might have compounded the stress on the Bruchs RPE complex, resulting in the formation of CNVM in the slope of the FCE. The combined effect may also be the reason for the occurrence of CNVM in our patient, at a relatively younger age.

CNVM associated with FCE has a good response to single dose of intravitreal anti-VEGF and lower recurrence rates unlike the CNVM associated with AS. Secondary CNVM associated with AS needs multiple anti-VEGF injections and has progression and recurrence of the disease. This case resolved well with a single dose of intravitreal anti-VEGF, suggesting that FCE may also be the cause of CNVM rather than AS alone.

Conclusion

This case describes a heretofore unreported association of FCE in a patient with AS and secondary CNVM. AS CNVM, when associated with FCE, predominantly behaves like an FCE-associated CNVM with better treatment response and good visual outcome with fewer injections.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.