Subthreshold laser treatment for retinal arterial macroaneurysm associated with exudative maculopathy.

In this article, we present a case of retinal arterial macroaneurysm (RAM) complicating into exudative maculopathy who was successfully treated with subthreshold laser treatment (STLT). A 45-year-old Indian female was referred to our institution with diminution of vision in her left eye for 1 month with best-corrected visual acuity (BCVA) of counting fingers at 2 m in the left eye. A dilated fundus examination of the left eye revealed deposition of lipid exudates in the macular area and a reddish round vascular lesion superior to macula around two disc diameters from the center of fovea. Optical coherence tomography (OCT) showed serous neurosensory detachment in the macular area in the left eye. Fundus fluorescein angiography showed leakage at the site of vascular lesion in the arterial phase of angiogram. Laser treatment using subthreshold laser parameters was done with three mirror contact lens at the site of vascular lesion. Over the next 12-month follow-up, her BCVA as well as OCT picture improved gradually, and at the last follow up, her BCVA was 20/30 in the left eye with complete resolution of subretinal fluid as detected by OCT. STLT offers promising results in the treatment of symptomatic RAM without causing any complications.

Introduction

Retinal arterial macroaneurysms (RAMs) are fusiform or round dilations of the retinal arterioles that occur in the posterior fundus within the first three orders of arteriolar bifurcation. The superotemporal artery is the most common site of involvement, and women make up the majority of reported cases. It usually affects patients in their sixth to seventh decade of life with a strong association with systemic hypertension.[1] RAMs are usually asymptomatic but can present with a number of complications such as retinal edema, exudation, and hemorrhage.[2]

Treatment of RAM is controversial. Some investigators believe that visual prognosis is excellent in most patients as these lesions can thrombose and undergo spontaneous involution with clearing of macular fluid and exudates.[3] However, long-standing exudative maculopathy can lead to structural damage to retina with loss of photoreceptor cells and ultimately poor visual outcome.[4]

Many investigators consider direct laser photocoagulation of the vascular lesion if the lipid exudates coming from it threaten the fovea. However, many complications have been related to this treatment modality including retinal arteriolar occlusion with macular ischemia.[5] Subthreshold laser treatment (STLT) may be an alternative to conventional laser treatment in these patients, because reducing the laser exposure duration and applying subvisible laser burns may decrease the complication rate associated with conventional laser photocoagulation.[6]

Here, we present a case of retinal arteriolar macroaneurysm with exudative maculopathy in a middle-aged female who was successfully treated with subthreshold focal laser treatment with significant improvement of visual acuity after 12 months of follow-up.

Case Report

A 45-year-old Indian female was referred to our institution with diminution of vision in her left eye for 1 month. Her best-corrected visual acuity (BCVA) in the right eye was 20/20, and in the left eye, it was counting fingers at 2 m. On slit-lamp examination, no abnormality was seen in the anterior segment. Her intraocular pressure was 14 mmHg in both eyes. A dilated fundus examination of the left eye revealed deposition of lipid exudates in the macular area and a reddish round vascular lesion superior to macula around two disc diameters from the center of fovea [Figure 1]. Fundus picture of the right eye was normal. Optical coherence tomography (Stratus OCT, Carl Zeiss, Meditech Inc., Germany) showed serous neurosensory detachment in the macular area in the left eye [Figure 2]. Fundus fluorescein angiography showed leakage at the site of vascular lesion in the arterial phase of angiogram [Figure 3]. Laser treatment using subthreshold laser parameters was done with three mirror contact lens at the site of vascular lesion using infrared diode laser (810 nm) (Iris Medical Oculight, SLx Photocoagulator, Iridex Corp., Mountain View, CA). Laser settings were 125 μ spot size, 300 ms exposure, and a power of 1200 mW with 15% duty cycle. Laser spots were applied in two rows of burns surrounding it but not over the lesion to prevent arteriolar occlusion. At 3-month follow-up, there was significant improvement in BCVA (20/200) as well as reduced subretinal fluid on OCT [Figure 4]. Over the next 9-month follow-up, her BCVA as well as OCT picture improved gradually, and at 12-month follow-up, her BCVA was 20/30 in the left eye with complete resolution of subretinal fluid as detected by OCT [Figure 5].

Figure 1

Fundus photograph at presentation

Figure 2

Optical coherence tomography at presentation

Figure 3

Fundus fluorescein angiography picture at presentation

Figure 4

Optical coherence tomography at 3 months following laser treatment

Figure 5

Optical coherence tomography at 12 months' post-Laser treatment

Discussion

The best approach to the management of RAM is still a matter of debate. Spontaneous involution can occur in some patients, but the long-standing exudative macular detachment may lead to progressive photoreceptor cell loss with deterioration of visual function.[7] Thus, in cases of symptomatic RAM, which are associated with exudative manifestations involving the fovea, early treatment should be attempted to avoid irreversible damage to anatomic and visual function. Nowadays, conventional laser therapy with visible laser burn is the most commonly employed treatment modality for symptomatic RAM.[8] Several complications can occur with conventional threshold laser treatment for macular lesions, which include arteriolar occlusion, scarring of the retina, increase in fluid accumulation under macula, laser scar enlargement, and subretinal fibrosis.[5910] The use of STLT represents an alternative approach in the treatment of RAM with an advantage of reduced complication rate. In the past, STLT has shown good results in treating macular edema associated with branch retinal vein occlusion and diabetic retinopathy.[611]

We used STLT in our patient and we were successful in improving her visual function without any evidence of complications such as arterial obliteration, increased retinal exudation, or fibrosis. The actual mechanism by which STLT works is not fully understood, but it can be hypothesized that STLT improves the balance in cytokine release by causing selective damage to the retinal pigment epithelial cells.[1213] Thus, STLT may have its effect by reducing the vascular permeability and improved fluid reabsorption by promoting vascular repair. In conclusion, STLT offers promising results in the treatment of symptomatic RAM without causing any complications. In the future, a multicenter, randomized clinical trial is warranted to study the effect of this treatment modality on large scale and the most appropriate settings to be employed.

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.