Hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome: A case report

Abstract

BACKGROUND

Hammered silver appearance of the corneal endothelium is considered a characteristic change in iridocorneal-endothelial syndrome. Herein we report an interesting case of hammered silver appearance of the corneal endothelium in Fuchs uveitis syndrome (FUS).

CASE SUMMARY

A 49-year-old man with progressive vision loss in the right eye for one year was admitted to our hospital. The clinical manifestations of the patient’s right eye were mild conjunctival hyperemia, scattered stellate keratic precipitates on the corneal endothelium, normal depth anterior chamber, 2+ cellular reaction in the aqueous humor, diffuse iris depigmentation, absence of synechia, Koeppe nodules, opalescent lens, and vitreous opacity. FUS and a complicated cataract were diagnosed based on the typical clinical manifestations. The corneal endothelial changes were recorded in detail by slit-lamp examination, specular microscopy, and in vivo confocal microscopy before cataract extraction, revealing a hammered silver appearance of the corneal endothelium in the affected eye, a wide-band dark area, as well as irregular corneal endothelial protuberances and dark bodies of various sizes. Subsequently, the patient underwent phacoemulsification combined with intraocular lens implantation, and his postoperative visual acuity recovered to 1.0.

CONCLUSION

Hammered silver appearance of the corneal endothelium in FUS, which is considered a more serious manifestation of endothelial damage, is rare and may be caused by many irregular protrusions in the corneal endothelium.

Key Words: Fuchs uveitis syndrome, Corneal endothelium, Hammered silver, Case report

Core Tip: A 49-year-old man was diagnosed with Fuchs uveitis syndrome (FUS) and a complicated cataract based on typical clinical manifestations. Slit-lamp examination, specular microscopy, in vivo confocal microscopy revealed a hammered silver appearance of the corneal endothelium in the affected eye, a wide-band dark area, as well as irregular corneal endothelial protuberances and dark bodies of various sizes. Subsequently, the patient underwent phacoemulsification combined with intraocular lens implantation. Hammered silver appearance of the corneal endothelium in FUS, which is considered a more serious manifestation of endothelial damage, is rare and may be caused by many irregular protrusions in the corneal endothelium.

INTRODUCTION

Fuchs uveitis syndrome (FUS) also referred to as Fuchs heterochromic uveitis or Fuchs heterochromic iridocyclitis, was first described by Ernst Fuchs in 1906. It is non-granulomatous uveitis primarily affecting a single eye, characterized by low-grade activity, diffuse depigmentation, and diffuse or central distribution of stellate keratic precipitates (KPs) on the corneal endothelium. Patients typically present in their third or fourth decades, and both sexes are equally affected[1,2]. Complicated cataracts, vitreous opacity, and secondary glaucoma are common complications[1], with cataract treatment leading to a good prognosis[3-5].

Inflammation of the anterior segment is known to affect the corneal endothelium[6]. In vivo confocal microscopy (IVCM) has also been used to characterize KPs and to evaluate endothelial cell layer damage in FUS, revealing that FUS is characterized by dendriform KPs and is associated with decreased endothelial cell density and altered endothelial cell morphology[7]. However, the appearance changes of the corneal endothelium on slit lamp examination are rarely described. Herein, we report an interesting case of hammered silver appearance of the corneal endothelium in FUS.

CASE PRESENTATION

Chief complaints

A 49-year-old man with progressive vision loss in the right eye for one year was admitted to our hospital.

History of present illness

The patient had been diagnosed with uveitis of the right eye three years previously and was treated with hormone eye drops and nonsteroidal anti-inflammatory eye drops in several hospitals.

History of past illness

The patient had no systemic diseases.

Personal and family history

There was no remarkable family history.

Physical examination

The visual acuity was counting fingers/40 cm in the right eye and 1.0 in the left eye. Intraocular pressure was 12 mmHg in the right eye and 14 mmHg in the left eye. The clinical manifestations of the patient’s right eye were mild conjunctival hyperemia, scattered stellate KPs on the corneal endothelium, normal depth anterior chamber, 2+ cellular reaction in the aqueous humor, diffuse iris depigmentation (Figure 1A), absence of synechia, Koeppe nodules (Figure 1B), opalescent lens, and vitreous opacity. No obvious abnormalities were observed in the anterior segment of the left eye (Figure 1C).

Figure 1 Slit lamp examination. A: Anterior segment image of the affected eye; B: Koeppe nodules at the pupillary margin of the affected eye; C: Anterior segment image of the fellow eye.

Laboratory examinations

Laboratory tests were normal, including red and white blood cell counts, C-reactive protein, erythrocyte sedimentation rate, anti-streptolysin O titer, rheumatoid factor, and antinuclear antibody. Rubella immunoglobulin G (IgG) detected in the aqueous humor of the affected eye was 14.24 IU/mL, which was higher than the normal value.

Imaging examinations

B-ultrasound revealed vitreous opacity in the affected right eye (Figure 2A). Ultrasound biomicroscopy showed a shallow anterior chamber, lens opacification, and expansion (Figure 2B). During gonioscopy, fresh bleeding was noted at the anterior chamber angle of the affected eye (Figure 2C). Slit-lamp examination revealed a hammered silver appearance of the central corneal endothelium in the affected eye (Figure 2D). Specular microscopy showed a wide-band dark area in the affected eye (Figure 3A), whereas the fellow eye showed a completely normal endothelial morphology (Figure 3B). The endothelial cell density of the affected eye was 2158 cells/mm², and the coefficient of variation was 46%, whereas the endothelial cell density of the fellow eye was 2836 cells/mm², and the coefficient of variation was 25%. IVCM revealed irregular corneal endothelial protuberances and dark bodies of various sizes in the affected eye (Figure 4). The corneal endothelial cells around the lesion were enlarged, and the corneal endothelium was evaluated before cataract extraction.

Figure 2 Clinical features of the affected eye. A: B-ultrasound revealed vitreous opacity in the affected right eye; B: Ultrasound biomicroscopy showed a shallow anterior chamber and lens opacification and expansion; C: Fresh bleeding at the anterior chamber angle of the affected eye during gonioscopy; D: Hammered silver appearance of central corneal endothelium in the affected eye.

Figure 3 Specular microscopy examination. A: Wide-band dark area of the affected eye revealed by specular microscopy; B: Normal endothelial morphology of the fellow eye.

Figure 4 In vivo confocal microscopy examination. A-D: Irregular corneal endothelial protuberances and dark bodies of various sizes in the affected eye (images from different areas) are visible.

FINAL DIAGNOSIS

FUS and a complicated cataract were diagnosed based on the typical clinical manifestations.

TREATMENT

During hospitalization, the anterior chamber quickly became shallow, with ultrasound biomicroscopy revealing opacity and expansion of the lens. Subsequently, phacoemulsification combined with intraocular lens implantation was performed in the right eye, and the postoperative visual acuity recovered to 1.0.

OUTCOME AND FOLLOW-UP

One year after cataract surgery, a telephone follow-up was conducted due to the pandemic of coronavirus disease 2019. The patient went to the ophthalmology department of a local hospital for further consultation. The visual acuity of his right eye was 0.8 and the intraocular pressure was normal.

DISCUSSION

The diagnosis of FUS is often based on clinical manifestations, and it is one of the frequently misdiagnosed forms of uveitis[8]. Yang et al[9] developed a novel set of revised diagnostic criteria for FUS with high sensitivity and specificity, confining the diagnosis to three essential criteria and five associated findings as support for the diagnosis, which are simpler and superior. In the present case, the clinical manifestations were in complete agreement with the diagnostic criteria for FUS.

Characteristic filiform hemorrhage and formation of hyphaema after anterior chamber paracentesis is a hallmark of FUS and is known as Amsler’s sign, which was first described by Amsler and Verrey[10] in 1946. Amsler’s sign can be spontaneous or associated with minor trauma, gonioscopy, applanation tonometry, pharmacological mydriasis, or cataract surgery[11]. The role of Amsler’s sign in diagnosing FUS is highly controversial, and paracentesis is unnecessary for patients with typical clinical manifestations[1]. Our patient showed Amsler’s sign during gonioscopy, which strongly supports the diagnosis of FUS, but no hemorrhage or other complications occurred during phacoemulsification.

The exact etiology of FUS remains unclear, but possible pathogenic mechanisms include sympathetic, immunological, hereditary, and infectious theories. Many of these theories have been largely disproven over the years, and rubella virus infection may be a possible etiological agent of FUS[12,13]. Metagenomic deep sequencing showed that persistent and active rubella virus infection is associated with FUS[14]. Treatment should be reserved for complications of FUS and not for inflammation associated with the disease[2]. In our case, the patient had not been vaccinated against rubella, and rubella IgG in the aqueous humor was increased, consistent with previous studies[15].

Alterations in corneal endothelial cells have been detected in patients with FUS, but there is no significant difference in endothelial cell density between the affected and healthy fellow eyes[16]. However, a decrease in endothelial cell density and percentage of endothelial hexagonal cells and an increase in polymegethism in FUS eyes compared to fellow eyes were detected in various studies[7,17]. Recent studies suggest that eyes with FUS have increased corneal densitometry values, especially in the posterior and midstromal layers of the cornea, which is considered to be due to impairment of endothelial cell function[18]. In our case, the endothelial cell density decreased, and the coefficient of variation increased compared with the contralateral eye.

In this case, we report a hammered silver appearance of the corneal endothelium in FUS. The hammered silver appearance of the corneal endothelium is common in iridocorneal-endothelial (ICE) syndrome and can also be seen with the corneal guttae present in primary endothelial dystrophy. Specular microscopy of ICE syndrome shows ICE cells with a typical dark-light reversal pattern[19], in this case, revealed a wide-band dark area of the affected eye, which does not support ICE diagnosis. Simultaneously, the contralateral eye of our patient was normal, ruling out the possibility of primary endothelial dystrophy. Recently, it has been reported that some patients with FUS have corneal guttae, but the authors did not describe whether they had a hammered silver appearance of the corneal endothelium[20]. At present, whether there are true corneal guttae in patients with FUS is controversial.

Labbé et al[16] observed hyperreflective deposits corresponding to KPs, smaller hyperreflective deposits, and hyporeflective small round defects in the affected eye of FUS using IVCM during a stable period. However, in our case, the inflammation had recently increased, the central corneal endothelium had a hammered silver appearance, and there were numerous irregular protrusions in the corneal endothelium, which may be the cause of the hammered silver appearance of the corneal endothelium, a more serious manifestation of the corneal endothelium damage. Potential damage to endothelial cells in patients with anterior uveitis includes direct contact with inflammatory cells or the role of proteins in the aqueous humor[6]. In this case, the corneal endothelial damage may be caused by active inflammation based on chronic inflammation.

CONCLUSION

This is a rare report of hammered silver appearance of corneal endothelium in FUS, possibly caused by many irregular protrusions in the corneal endothelium, which is considered a more serious manifestation of endothelial damage.