Dislocated Sömmering Ring with Decompensated Cornea Presenting 14 Years After Lens Aspiration and Anterior Vitrectomy: A Case Report and Literature Review

Background

In pediatric patients at a tertiary eye care hospital in Saudi Arabia, cataract is the cause of 12.1% of unilateral blindness and 6.3% of bilateral blindness [1]. A Sömmering ring is a form of post-cataract opacity after lens removal that forms due to the adhesion of the anterior capsule edges to the posterior capsule [2]. Generally, the ring is hidden behind the iris; therefore, it is unlikely to cause visual symptoms.

However, dislocation of the Sömmering ring can result in clinical sequelae. The most common complication of its anterior dislocation is glaucoma, while vision is affected when posterior dislocations obstruct the pupillary zone [3]. The current case report presents the signs, symptoms, and management of Sömmering ring manifesting 14 years after lens aspiration and anterior vitrectomy. Additionally, we present a review of the pertinent literature on this complication.

Case Report

A 20-year-old man came to the emergency room with right eye pain, photophobia, redness, and blurry vision for 2 days. He reported recurrent bouts of similar symptoms in the same eye for years. He had an unremarkable past medical history except for bilateral lens aspiration and anterior vitrectomy 14 years prior to the consultation for bilateral congenital cataract. Intraocular lens (IOL) power calculation was 0 diopters due to high myopia; thus, no IOL implantation was performed. Due to the delayed management of his cataracts, the patient had bilateral amblyopia.

Upon examination in the emergency department during the current episode, the uncorrected visual acuity (UCVA) was 6/200 in the right eye, which improved with pinhole testing to 20/400. The lids and lashes were normal. Intraocular pressure was 18.5 mmHg. The conjunctiva had moderate diffuse injection, and the cornea had 2+ diffuse edema with bullae and Descemet folds. The anterior chamber was deep with a peripheral ring of opacified lens material (Figure 1). The pupil was reactive, and iridodonesis was present. Aphakia was noted, and a dilated fundus exam was attempted; however, the view was hazy. B-scan ultrasonography indicated highly reflective material in the vitreous cavity and a flat retina (Figure 2). Posterior segment optical coherence tomography was performed and indicated a dry macula.

Examination of the left eye indicated an uncorrected visual acuity of 20/300, an intraocular pressure of 20 mmHg, and an aphakic eye with a clear cornea.

Upon pupil dilation of the right eye, spontaneous migration of the Sömmering ring into the vitreous cavity was observed.

Hence, medical treatment was initiated with sodium chloride eye drops and ointment, ofloxacin 0.3% eye drops, prednisolone acetate eye drops, and topical lubricating drops. The surgical retina team was also involved in the management, and the patient was scheduled for pars plana removal of the Sömmering ring after the cornea started to clear.

Discussion

Nowadays, cataract surgery has a high success rate with minimal postoperative complications [4]. The fibrogenic potential of the remaining lens epithelial cells residing in the capsule’s equatorial region is responsible for the formation of posterior capsular opacification (PCO), one of the commonest postoperative complications [3]. The epithelium proliferates, lines the posterior capsule, and grows around the margin of the anterior capsule. The Sömmering ring is a ring formed in the periphery of the lens capsule [5]. It was originally described in 1828 in deceased individuals with a previous history of cataract surgery [6]. By definition, the nucleus of the lens is always absent after trauma or operative intervention in cases with Sömmering ring [5].

Our patient had a history of bilateral lens aspiration and anterior vitrectomy without IOL implantation for bilateral congenital cataract and axial myopia. Fourteen years later, he presented with corneal edema and Sömmering ring dislocation in the anterior chamber in his right eye. Published reports of dislocated Sömmering rings are rare. Multiple factors predis-posed this patient to Sömmering ring formation, including cataract surgery at an early age and postoperative aphakia [5,8,9]. Wilson et al noted that Sömmering ring formation frequently occurs when lensectomy is performed early in childhood [7]. A few factors may be associated with this, including performing smaller anterior capsulotomy that can promote proper lens fiber differentiation and lens regeneration as more lens epithelial cells are retained under the anterior capsule than when larger capsulotomy was performed [8]. The adhesion of anterior and posterior capsulotomy edges to each other creates a sealed microenvironment that can prevent inflammatory cytokines from aiding the transformation of epithelial to mesenchymal cells.

The Sömmering ring is held in position in the retro-iridal space by the ciliary zonule and can only be seen in cases of dislocation [5]. Guha observed that myopia is a predisposing factor for ring dislocation after reviewing 11 cases of dislocated Sömmering rings. Of these cases, 8 cases were myopic. The dislocation is attributed to myopia-related changes in the eye, such as zonule degeneration, ciliary body atrophy, vitreous liquefaction, and a deep anterior chamber. Further findings from Guha’s review indicated that 5 of the 11 cases experienced spontaneous ring dislocation, and secondary glaucoma developed in 6 cases [9].

Aphakia is one of the most frequent factors, but there are also reports of Sömmering rings in pseudophakic eyes [10]. Recently, Awad et al presented a case of a 65-year-old man with a history of cataract surgery 53 years earlier who remained aphakic to treat high myopia. However, despite this long duration without complications, the Sömmering ring was dislodged after blunt trauma [3]. Akal et al reported a Sömmering ring dislocated into the anterior chamber, causing a pupillary block in an 84-year-old patient who had undergone cataract extraction several years before and remained aphakic due to high myopia [11]. Additional factors that can predispose to ring dislocation include formation at an early age, senile changes in the eye, degenerative alterations within the ring, and aphakia [5].

Anterior dislocation of the Sömmering ring is more common, and patients can present with glaucoma if it occurs [12]. Peck et al reported a case of an anteriorly dislocated Sömmering ring causing worsening corneal edema and open-angle glaucoma secondary to inflammation [4]. Kung et al reported a case of anterior dislocation of an enlarged Sömmering ring after phacoemulsification in an 80-year-old woman, who presented with progressive synechial angle closure without pupillary block; interestingly, the eye was pseudophakic [13]. Mechanisms proposed for angle closure include progressive angle closure without pupillary block and acute angle closure with pupillary block from an enlarged Sömmering ring [12]. Posterior dislocation of the Sömmering ring has also been observed, resulting in significant visual problems [9]. Tooke described 3 cases of Sömmering rings dislocated in the vitreous cavity [14]. Posterior dislocation of the Sömmering ring can lead to inflammatory signs that mimic uveitis where slit-lamp examination will not reveal the cause [3].

The current case illustrates the potential ophthalmic morbidity associated with PCO and highlights the importance of efforts to minimize the incidence of PCO [4]. A recent study indicates that the rate of PCO following cataract extraction has decreased since adopting alternative approaches such as inthe-bag IOL implantation, advancement in IOL materials and design, and improvement in surgical techniques and approaches [11]. Compared to single-piece IOLs, three-piece IOLs have been shown to significantly reduce the formation of PCO due to their larger size [4]. Menapace described a technique in which a posterior capsulorhexis is performed, then the IOL optic is buttoned-in into the posterior capsulorhexis opening[15]. Additional polishing of the capsule was also performed in some of his patients to prevent capsular fibrosis and PCO formation, specifically the Sömmering ring.

In the present case, the corneal decompensation and the vision loss could have been prevented if the Sömmering ring had been proactively removed before dislocation. However, due to the rarity of this complication and the absence of symptoms, the Sömmering ring developed, as it is commonly hidden behind the iris and away from the visual axis. Therefore, prophylactic cortical removal is crucial in primary lensectomy surgery to reduce the risk of Sömmering ring formation. This case demonstrates the inflammatory potential of a Sömmering ring in the anterior chamber, especially if it comes in contact with the corneal endothelium. Therefore, it is essential to consider immediately removing the Sömmering ring from the anterior chamber to prevent further complications and achieve optimal management. Also, the current case highlights the importance of considering IOL implantation even in cases where small lens powers are needed to reduce the risk of Sömmering ring formation and dislocation. Theoretically, the IOL can act as a barrier to prevent such a complication when a dislocation occurs.

Conclusions

A Sömmering ring is a post-cataract opacity (PCO) that develops when the edges of the anterior and posterior capsules adhere together. Several complications can result from anterior or posterior dislocation of the Sömmering ring, such as glaucoma, obstruction of the visual axis, and corneal decompensation. Prompt surgical removal is essential to avoid permanent damage if complications result from dislocation of the Sömmering ring. IOL implantation in myopic eyes can be considered to reduce the likelihood of Sömmering ring formation in the future and its complications.