Fundus autofluorescence imaging to document evolution, progression and healing pattern of serpiginous choroiditis

Introduction

Fundus autofluorescence (FAF) imaging is an in vivo imaging method based upon mapping of lipofuscin distribution in retinal pigment epithelium (RPE) as well as of other fluorophores.[1] It is non-invasive and provides clinically useful information about several retinal diseases beyond that obtained by conventional imaging techniques. Previous studies have reported the role of FAF in serpiginous choroiditis (SC).[2,3,4,5] We described a pattern of FAF findings during entire course (evolution, progression and healing) of SC lesions.

Case Report

A 25-year-old male, known case of healed peripheral SC in the left eye, was noted to have a small yellowish macular lesion of SC [Figure 1a], hyperautofluorescent on FAF [Figure 1b]. Best-corrected visual acuity (BCVA) was 6/6, N/6.

Figure 1.

Left eye color fundus photographs showing (a, c and e): Evolving lesion of serpiginous choroiditis in macula. FAF showing (b): Hyperautofluorescence of early lesion, (d): Superior border of the lesion has become hypoautofluorescent, (f): Area where the lesion begun has become hypoautofluorescent

The patient was started on tapering course of oral prednisolone, at 1 mg/kg body weight. At 2 weeks, the fundus lesion had enlarged [Figure 1c]. BCVA was 3/60, N/36. On FAF, the lesion appeared hyperautofluorescent, with hypoautofluorescence along the superior border [Figure 1d]. On careful evaluation, faint hyperautofluorescence extended over a wide area toward the disc [Figure 1d]. At 3 weeks, clinical picture remained the same [Figure 1e]. On FAF, the area of beginning of the lesion had become hypoautofluorescent and the wide area of faint hyperautofluorescence toward the disc was more prominent now [Figure 1f].

At 5 weeks, the fundus lesion had enlarged exactly along the area of faint hyperfluorescence as indicated on FAF in early stage [Figure 2a]. On FAF, the border had become hyperfluorescent, whereas the rest of the lesion showed speckled hypo- and hyperfluorescence [Figure 2b]. On weekly follow-ups, the border of the lesion appeared less active [Figures 2c and e]. FAF showed a pattern of healing. First, there was sharpening of entire border as a distinct well-defined zone [Figure 2d]. Next, the border showed a decrease in the width of hyperautofluorescence [Figure 2f].

Figure 2.

Left eye color fundus photographs showing (a, c and e): Progressing lesion. FAF showing (b): Hyperautofluorescent border whereas the rest of the lesion shows combination of speckled hypo- and hyperautofluorescence, (d): Sharpening of hyperautofluorescent border, (f): Decrease in width of hyperautofluorescent border

Subsequently, the lesion started healing [Figures 3a, c, e]. On FAF, the border gradually became less distinct with increasing hypoautofluorescent patches [Figures 3b, d, f]. On 2 weekly follow-ups, fundus examination showed the healed lesion [Figures 4a, c, e]. On FAF, the lesion including border was largely hypoautofluorescent, with the presence of few hyperautofluorescent specks [Figures 4b and d]. The area of beginning of the lesion was still noticeable as the most hypoautofluorescent part [Figure 4f]. At last visit, the patient was on the maintenance dose of Tab. prednisolone 10 mg/day, with BCVA of 6/60, N/36.

Figure 3.

Left eye color fundus photographs showing (a, c and e): Healing lesion with gradual disappearance of the active sharply demarcated border. FAF showing (b, d, f): Border of the lesion has gradually become less distinct because of an increase in the hypoautofluorescent patches

Figure 4.

Left eye color fundus photographs showing (a, c and e): Healed lesion. FAF showing (b, d): Entire lesion including the border is now largely hypoautofluorescent, with few hyperautofluorescent specks, (f): Area where the lesion begun remains the darkest part of the hypoautofluorescent lesion

Discussion

There is a pattern of FAF findings during entire course (evolution, progression and healing) of SC lesions.

Evolution

During initial stages of evolution, the lesion was hyperautofluorescent. Unlike Piccolino et al.,[3] we did not notice any hypoautofluorescence in early stage. Notably, faint hyperautofluorescence extending over a large area was predictive of future extent of the lesion. This faint hyperautofluorescence might be representative of actual extent of RPE involvement, which is not yet clinically apparent. Thus, FAF can predict future evolution of a lesion quite accurately in initial stage.

Progression

Autofluorescence of the border indicated activity of the lesion. More hyperautofluorescent border represented the advancing lesion. This can be clinically useful to predict progression.

Healing

Healing of the lesion was indicated on FAF by sharpening of hyperautofluorescent borders, followed by decreased width of hyperfluorescence. These were early signs that appeared before the healing border became hypoautofluorescent. The pattern of healing was in order of evolution. The area of beginning of the lesion was the most hypofluorescent. Though the lesion was clinically healed, few specks of hyperautofluorescence were still present scattered within the hypoautofluorescent lesion. The development of complete hypoautofluorescence might need more time.

FAF imaging is an important investigation tool in our daily clinical practice and should be well utilized.