Vitrectomy for Symptomatic Asteroid Hyalosis

Abstract

Purpose:

Acute vision loss may accompany complete or partial posterior vitreous separation in asteroid hyalosis (AH), and pars plana vitrectomy may resolve these symptoms.

Methods:

Six individuals with AH and acute vision loss associated with diagnosed posterior vitreous separation were treated with pars plana vitrectomy, and visual acuity (VA) recovery was monitored for 3 months.

Results:

The study patients’ preoperative VA ranged from 20/25 to 20/2500 (mean, 20/150; logMAR, 0.88). The average decrease in VA with anterior progression of the hyaloid was logMAR 0.70. Following surgical clearance of the asteroid bodies, VA returned to baseline within 1 month following vitrectomy in 2 eyes, and within 3 months in all eyes. Final VA was 20/20 to 20/200 (mean, 20/35; logMAR, 0.24).

Conclusions:

Patients with AH may present with acute onset of severe vision loss in association with posterior vitreous separation. Vitrectomy may be curative and restore vision.

Introduction

Asteroid hyalosis (AH) is a common, benign degenerative disease of the vitreous body in which dense aggregates of calcium and lipid collect in liquified vitreous. The term asteroid bodies (ABs) describes the appearance of refractile yellow plaques against a dark background, likening them to stars in the night sky. AH is associated with mild liquefaction of the vitreous body and a lower incidence of posterior vitreous detachment (PVD). ^1,2 The prevalence is estimated at 2%, and approximately 80% of cases are unilateral. ² Although the underlying cause is unknown, its prevalence increases with age and male sex. ²

Although prominent and occasionally obstructive to the examiner, ABs are typically of minor visual consequence to the affected individual. Difficulties in visualization for fundus examination and photography can often be overcome with optical coherence tomography (OCT) and fluorescein angiography to assess for macular and peripheral disease, respectively. ³ For the patient, the minimal symptoms are attributed, in part, to the typically sparse collections in the anterior vitreous and the consistent observation that ABs aggregate only in the vitreous gel without distributing into the liquid vitreous or appearing posterior to a PVD. ^2,4 Thus, it is uncommon to treat AH with pars plana vitrectomy (PPV). In the setting of a PVD, however, the ABs may concentrate in the anterior vitreous causing acute vision loss. The increased visual significance reflects the greater central density of these obstructive bodies and their concentration at the nodal point of the eye. ¹

Here we report a series of 6 eyes with acute vision loss following progressive vitreoretinal separation who underwent PPV with resulting functional improvement.

Methods

Patients were examined and followed by multiple providers at a tertiary care retinal practice, Associated Retinal Consultants PC in Royal Oak, Michigan. A retrospective review of medical records identified 6 eyes of 6 patients who had presented with acute decreased visual acuity (VA) in the setting of AH. Diagnosis was confirmed with fundus examination and photography. When possible, the status of the posterior vitreoretinal interface was confirmed with OCT. Data collected for each patient included sex, age at presentation, phakic status, best-corrected VA (BCVA) at initial presentation, BCVA prior to PVD when available, preoperative BCVA, BCVA at 1- and 3-month postoperative visits, final BCVA, and duration of patient follow-up. VA was reported in Snellen and logMAR notation with low vision of counting fingers and hand motion converted to Snellen and logMAR notation according to previously published scales. ⁵

Patients underwent PPV with 23- or 25-gauge instrumentation to remove the vitreous body including ABs. The status of the posterior hyaloid was confirmed intraoperatively, and a complete PVD was achieved in each case. Intraoperative scleral depression was performed to inspect for peripheral pathology. Institutional review board approval was obtained, and the study adhered to the tenets of the Declaration of Helsinki.

Results

The median age of the 4 men and 2 women included in this study was 74 years (range, 57-83 years). One patient was phakic and the other 5 were pseudophakic in the affected eye.

The BCVA prior to PVD was not available for all patients because some were referred by an outside provider and previous records were not shared. Of the 3 eyes for which pre-PVD BCVA was known, it ranged from 20/25 to 20/200 (mean 20/55, logMAR 0.43).

All 6 patients reported an acute or subacute decline in vision with a new complete (n = 3) or partial (n = 3) PVD diagnosed by clinical evaluation and OCT (Figure 1). Preoperative BCVA ranged from 20/25 to 20/2500 (mean 20/150, logMAR 0.88). The average decrease in VA with anterior progression of the hyaloid was logMAR 0.70. Surgery was offered to patients according to the degree of vision loss and the patient’s motivation to improve vision. An average of 21 ± 24 days elapsed between a patient’s first examination in our office for acute PVD with vision loss and the corresponding surgery.

Figure 1.

Preoperative and postoperative optical coherence tomography (OCT) of 3 patients with acute visual acuity decrease coincident with asteroid hyalosis and vitreoretinal separation. (A) A 71-year-old man had a posterior vitreous detachment that was confirmed on preoperative OCT. (C) Vitreoschisis in a 74-year-old woman with focal peripapillary attachment. (E) Vitreoschisis in an 81-year-old woman with underlying age-related macular degeneration. (B, D, and F) OCT following pars plana vitrectomy for these patients, respectively, confirming complete removal of the posterior hyaloid. VA indicates visual acuity.

Comorbidities contributing to baseline subnormal vision among the patients in this study included Kjer dominant optic atrophy, dry age-related macular degeneration (AMD), and neovascular AMD. None of these conditions were found to contribute to the acute vision loss reported. For 1 patient, a vitreous biopsy was collected at the time of the vitrectomy and submitted for cytology and culture, both of which were unremarkable.

Intraoperatively, a complete PVD was confirmed under microscopic observation in 2 eyes; the other 4 eyes showed partial elevation of the hyaloid with vitreous cortex remaining on the posterior retina (Figure 2). The majority of vitrectomies were performed with 25-gauge instrumentation, with 1 case conducted with 23-gauge instrumentation. Intraocular steroid was not used for visualization, and no peripheral retinal pathology was identified on intraoperative examination in any of the eyes. After surgical clearance of the ABs, BCVA returned to baseline within 1 month following vitrectomy in 2 eyes, and within 3 months in all eyes for which pre-PVD BCVA was available. Among the 3 eyes without pre-PVD BCVA available for review, the preoperative BCVA had ranged from 20/25 to 20/800 (mean 20/50, logMAR 0.43) and improved to 20/20-20/30 at postoperative month 1, although 1 patient did not have data collected for this time point. Overall, final BCVA ranged from 20/20 to 20/200 (mean 20/35, logMAR 0.24) (Table 1). There were no complications resulting from vitreoretinal surgery. VA outcomes and underlying conditions for all patients are listed in Table 2.

Figure 2.

Intraoperative photographs of pars plana vitrectomy from the patient with the optical coherence tomography shown in Figure 1, A and B. The images highlight (A and B) dense asteroid bodies in the anterior vitreous and (C) the presence of a posterior vitreous detachment confirmed intraoperatively.

Table 1.

Baseline Patient Characteristics, Posterior Hyaloid Status, and Visual Acuity Outcomes.

Characteristic	Value
Total eyes, No.	6
Right	5
Left	1
Total patients, No.	6
Men	4
Women	2
Age at symptom onset, mean (range), y	74 (87-53)
Complete PVD intraoperatively, No.	2
Vitreoschisis intraoperatively, No.	4
Preoperative VA, mean (range), Snellen	20/150 (20/25-20/2500)
Postoperative VA at 1 mo, mean (range), Snellen	20/40 (20/20-20/200)
Final postoperative VA, mean (range), Snellen	20/35 (20/20-20/200)
Final follow-up duration, mean (range), mo	13.5 (2-31)

Abbreviations: PVD, posterior vitreous detachment; VA, visual acuity.

Table 2.

Patient Outcomes and Underlying Conditions.

Patient No.	Baseline VA	Preoperative VA	Hyaloid status (confirmed intraoperatively)	Postoperative VA, 1 mo	Final VA	Underlying ophthalmic conditions affecting VA	Postoperative complications
1	20/200	20/2500	Complete PVD	20/200	20/200	Dominant optic atrophy	None
2	20/25	20/40	Partial PVD	20/20	20/20	None	None
3	NA	20/25	Complete PVD	20/20	20/20	None	None
4	NA	20/800	Partial PVD	20/30	20/30	Dry AMD	None
5	NA	20/30	Partial PVD	NA	20/20	None	None
6	20/30	20/200	Partial PVD	20/30	20/30	Wet AMD	None

Abbreviations: AMD, age-related macular degeneration; NA, not available; PVD, posterior vitreous detachment; VA, visual acuity.

Case 1

An 81-year-old woman with pseudophakia, bilateral neovascular AMD, and AH presented for acute decreased vision in her left eye (patient 6). Her right eye had advanced atrophic changes secondary to AMD resulting in chronic low vision and was being observed. Her left eye received regular antivascular endothelial growth factor injections and provided useful vision with a baseline BCVA of 20/30. At the time of presentation for acute decreased vision, OCT showed no evidence of recurrent subretinal fluid or hemorrhage. However, a new PVD with extensive AH was noted in her left eye. Her VA declined to BCVA 20/200 over the subsequent 2 months with no attributable new macular pathology. PPV was performed on the left eye with vitreous biopsy that excluded intraocular lymphoma. The acute PVD was confirmed. Postoperative vision recovered to BCVA of 20/50 at month 1 and was at baseline BCVA (20/30) by month 3. She has continued with antivascular endothelial growth factor treatment and has maintained 20/40 vision with 31 months of follow up.

Case 2

A 58-year-old man without significant ophthalmic history presented as a new patient with gradually worsening vision and floaters in his right eye (patient 5). The examination was notable for BCVA of 20/200 and 20/15 in the right and left eyes, respectively. Ophthalmoscopy revealed AH in the right eye and partial PVD in both eyes. PPV was performed on the right eye, and a partial PVD was confirmed intraoperatively. Complete posterior vitreous separation was achieved surgically, and no other vitreoretinal pathology was noted. Postoperative assessment at 1 month was delayed, but at 3 months he remained phakic and his BCVA was 20/20.

Case 3

An 83-year-old man with a history of pseudophakia, AH, and dominant optic atrophy with baseline vision of 20/200 in both eyes presented for evaluation of acute vision loss in the right eye. Examination revealed decreased VA to 20/2500 in the right eye. No view of the posterior pole was possible with ophthalmoscopy or OCT; however, ultrasonography demonstrated the retina to be attached and revealed vitreous opacities consistent with AH and a PVD. He underwent PPV, which confirmed no acute retinal pathology. Vision recovered to 20/200 at postoperative month 1 and remained stable for subsequent visits.

Conclusions

Although AH is typically associated with minimal subjective complaints, posterior vitreous separation appears to concentrate ABs into the anterior vitreous, thereby increasing their density in the central visual axis and causing marked visual impairment. PPV is an established treatment for AH that restores the clinician’s view of the posterior pole. ^6,7 In the uncommon circumstance of visual symptoms, vitrectomy has also been shown to improve VA, although in most prior series the status of the posterior hyaloid was not apparent. ⁸ Our case series demonstrated that PPV dramatically improved vision loss caused by acute posterior vitreous separation in eyes with AH, including cases with vitreoschisis.

The posterior vitreous is typically not detached in eyes with AH, and the degenerative condition is often associated with strong vitreoretinal adhesions. ⁹ Mochizuki et al reported that eyes with clinically diagnosed PVD and inconclusive preoperative OCT assessment are often found to have incomplete vitreoretinal separation noted intraoperatively. ¹⁰ Although the patients in our series noted rapid visual decline associated with a concentration of ABs in the anterior vitreous, as would be expected in the setting of a PVD, vitreoschisis could be appreciated in several preoperative OCTs and was confirmed intraoperatively in 4 cases (see Figure 1, C and E). In addition, our case series confirmed other reports in the literature that found complete PVDs can occur in the setting of AH. ¹

Patients with AH may present with an acute onset of severe vision loss in association with a partial or complete PVD. In these uncommon situations, vitrectomy may be curative and restore vision to previous levels. We recommend that in the absence of other vitreoretinal pathology that explains significant vision loss, vitrectomy be offered to patients with AH who experience significant declines in BCVA, particularly in the setting of a subacute or acute partial or complete PVD. We further recommend that patients be counseled during routine examinations about the possibility of vision loss occurring by this mechanism.