Vitrectomy in patients with decreased visual acuity secondary to asteroid hyalosis

Asteroid Hyalosis: An Update on Prevalence, Risk Factors, Emerging Clinical Impact and Management Strategies

Asteroid hyalosis (AH) is a benign clinical entity characterized by the presence of multiple refractile spherical calcium and phospholipids within the vitreous body. First described by Benson in 1894, this entity has been well documented in the clinical literature and is named due to the resemblance of asteroid bodies on clinical examination to a starry night sky. Today, a growing body of epidemiologic data estimates the global prevalence of asteroid hyalosis to be around 1%, and there is a strong established association between AH and older age. While pathophysiology remains unclear, a variety of systemic and ocular risk factors for AH have recently been suggested in the literature and may provide insight into possible mechanisms for asteroid body (AB) development. As vision is rarely affected, clinical management is focused on differentiation of asteroid hyalosis from mimicking conditions, evaluation of the underlying retina for other pathology and consideration of vitrectomy in rare cases with visual impairment. Taking into account the recent technologic advances in large-scale medical databases, improving imaging modalities, and the popularity of telemedicine, this review summarizes the growing body of literature of AH epidemiology and pathophysiology and provides updates on the clinical diagnosis and management of AH.

Vitrectomy for Symptomatic Asteroid Hyalosis

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.

Impact of asteroid hyalosis on internal higher-order aberrations in eyes with cataract accompanied by acoustic shadows on swept-source optical coherence tomography examination

Increased internal higher-order aberrations (HOAs) have been reported in eyes with asteroid hyalosis, which is usually asymptomatic. This report describes 2 patients with cataract and concurrent asteroid hyalosis. In the first case, internal HOAs were within the normal range, and swept-source optical coherence tomography (SS-OCT) did not show acoustic shadows. After cataract surgery, visual acuity improved and internal HOAs remained within normal limits. However, in the second case, SS-OCT revealed multiple acoustic shadows, presumably due to asteroid hyalosis, and internal HOAs increased in both eyes. After combined vitrectomy and cataract surgery, visual acuity and the internal HOA values improved in both eyes, and acoustic shadows disappeared on SS-OCT. Phacovitrectomy should be considered if the cause of visual impairment is cataract and asteroid hyalosis. Objective assessment of internal HOAs by a wavefront sensor and checking for acoustic shadows on SS-OCT might be useful in detecting this combination of ophthalmic conditions.

To Treat or Not to Treat: Management Options for Symptomatic Vitreous Floaters

Vitreous floaters are a common cause for presentation to ophthalmologists, and may significantly affect visual function. In the absence of some more serious underlying pathology such as uveitis, many patients may not experience significant persistent visual impairment from floaters. For some patients, the symptomatic effects of floaters may persist. For these patients, treatment options are available, of which the most commonly reported is vitrectomy. Other treatment modalities have also become more common, notably YAG vitreolysis. Selection of appropriate patients for surgery is often difficult, in part due to the relative lack of objective outcomes with which to measure both visual impairment and improvement post-procedure. Although well-tolerated, vitrectomy does carry with it risks, including iatrogenic retinal breaks, retinal detachment, and in phakic patients, subsequent cataract formation. Techniques such as small gauge vitrectomy, intraoperative examination and treatment of breaks or other worrying lesions, and careful consideration of the need for posterior vitreous detachment induction may help limit the incidence of these adverse events. For other treatment options such as YAG vitreolysis, research and clinical experience remain more limited, and as such the long-term efficacy and risks of these therapies are still unclear. Here, we review the evidence surrounding the role of vitrectomy and YAG vitreolysis in the treatment of vitreous floaters and potential means to minimize therapeutic complications.

[Asteroid hyalosis]

The article analyzes existing information on clinical and experimental studies of vitreous changes in asteroid hyalosis, historical aspects of how this condition was studied over the past hundred years, its occurrence and pathogenesis. Results of various studies were used to evaluate current understanding of the forms and elemental composition of phospholipid mineral sedimentation on vitreous structures and methods of its examination. The problem of intravital assessment of the condition of vitreous body was analyzed, and a method was suggested for studying the macrostructure of hyaloid tracts and the state of the vitreous body by means of digital ultrasound in patients with asteroid hyalosis.

Asteroid hyalosis-a comprehensive review

Asteroid hyalosis is a relatively common cause of vitreous opacities, which is possibly associated with diabetes mellitus and hereditary pigmentary retinopathies. We review the history, epidemiology, and biochemistry of asteroid hyalosis, as well as its relationship with ocular and systemic conditions. We describe imaging modalities used for diagnostic evaluations in cases of severe asteroid hyalosis and propose hypotheses regarding its lack of significant effects on vision. We discuss cataract surgery in patients with asteroid hyalosis and the selection of intraocular lenses for implantation.

Case of asteroid hyalosis that developed severely reduced vision after cataract surgery

BACKGROUND

To report our findings in a patient with asteroid hyalosis (AH) who had a severe reduction of his visual acuity following cataract surgery. The vision was improved by vitreous surgery.

CASE PRESENTATION

The patient was an 81-year-old man. Following cataract surgery on his left eye, his decimal best-corrected visual acuity (BCVA) was markedly reduced from 0.2 to 0.02. A large number of asteroid bodies (ABs) was observed to be concentrated on the posterior surface of the implanted intraocular lens. Ultrasound B-mode images showed turbidity of the vitreous that was denser in the anterior vitreous where the ABs were concentrated. During vitrectomy, the ABs were observed to be concentrated in the anterior vitreous cavity, and a complete posterior vitreous detachment (PVD) was present. After vitrectomy successfully removed the ABs, the visibility of the fundus improved and the BCVA recovered to 1.0.

CONCLUSION

We suggest that the visual impairment after the cataract surgery was due to the concentrated ABs in the anterior vitreous cavity. The clustering of the ABs in the anterior vitreous cavity was most likely caused by the PVD that developed during the cataract surgery.

Increased internal higher-order aberrations as a useful parameter for indication of vitrectomy in three asteroid hyalosis cases

We report three asteroid hyalosis cases in which internal higher-order aberrations (HOAs) were improved concomitant with improved visual symptoms after vitrectomy. Cases 1 and 2 reported severe floaters and glare disability, although their visual acuities were fairly good. Case 3 showed poor visual acuity since this patient also suffered from mild macular degeneration. For these three asteroid hyalosis cases, we were unsure if treatment with vitrectomy could improve visual symptoms. Therefore, we measured internal HOAs with an aberrometer, and found that the internal HOA values in these cases were high. We suspected that internal high HOAs values were associated with visual disturbance, and performed vitrectomy. After the vitrectomy, the internal HOA values in these three asteroid hyalosis cases markedly decreased, and visual symptoms improved. These observations suggested that measurement of internal HOAs may be useful to determine the indication for vitrectomy.

Pars plana vitrectomy for dystrophic calcification of a silicone intraocular lens in association with asteroid hyalosis

We present a case in which a pars plana vitrectomy (PPV) was performed to halt the progressive dystrophic calcification of an intraocular lens (IOL) and the need for an IOL exchange. With limited follow-up, the patient's visual complaints have resolved, the dystrophic calcification of the IOL has stabilized, and good visual acuity has been retained. To our knowledge, this is the first report of a patient with progressive dystrophic calcification of silicone IOLs in association with asteroid hyalosis treated primarily with a PPV. In certain cases, PPV may be considered in patients with dystrophic calcification in association with asteroid hyalosis and may prevent the need for a late IOL exchange.

FINANCIAL DISCLOSURE

Neither author has a financial or proprietary interest in any material or method mentioned.

Post-cataract surgery visual disturbance in a retinitis pigmentosa patient with asteroid hyalosis

A patient with retinitis pigmentosa showed visual disturbances following successful cataract surgery. He had a dense asteroid hyalosis in the eye before cataract surgery. After the surgery he noticed that his vision became worse. The visual disturbance was explained as being caused by the progression of retinal degeneration. Although the electroretinogram was non-recordable, the degeneration of macular area appeared relatively small. We considered that dense asteroid hyalosis was responsible for his visual disturbances, and pars plana vitrectomy (PPV) was performed to remove the asteroid hyalosis. After the PPV, rapid improvement of his visual acuity was observed. Cataract surgery may affect the status of asteroid hyalosis and cause rapid visual loss. PPV should be considered for retinitis pigmentosa patients with dense asteroid hyalosis, especially when a large decrease in visual acuity is noted shortly after cataract surgery.

Prevalence of and risk factors for asteroid hyalosis in Seoul, Korea

PURPOSE

To estimate the prevalence of asteroid hyalosis (AH) in Seoul, Korea, and to identify risk factors for the condition.

METHODS

A cross-sectional study with review of fundus photographs of subjects who received a health check-up between January 2006 and December 2006 at the Yonsei Medical Examination Center yielded 9,050 available cases (aged 40 years or older). AH was diagnosed retrospectively by the presence of cream-white spherical bodies within the vitreous, as seen in the fundus photographs.

RESULTS

The estimate prevalence of AH was 0.36%. Multivariate analysis showed that the prevalence of AH was significantly higher in older patients and in those with stroke history, hypertension history, and high serum lipid levels.

CONCLUSION

AH was relatively uncommon with the estimate prevalence of 0.36% in Seoul, Korea. The prevalence of AH correlated with age, stroke history, hypertension history, serum triglyceride levels, and low-density lipoprotein levels, with no gender bias. AH was not significantly associated with a history of diabetes, gout, heavy drinking, or current smoking.

Optical coherence tomography in asteroid hyalosis

PURPOSE

To demonstrate the clinical utility of optical coherence tomography (OCT) in diagnosing macular structural abnormalities in patients with asteroid hyalosis.

METHODS

Case series.

RESULTS

Seven eyes of seven patients underwent OCT due to inadequate funduscopic visualization secondary to asteroid hyalosis. Fluorescein angiography and B-scan ultrasonography were conducted for two patients but failed to provide diagnostic clarity. OCT provided definitive anatomical diagnoses that included macular epiretinal membrane, macular hole, traction retinal detachment, cystoid macular edema, and drusen. On the basis of OCT-assisted diagnoses, three patients elected to undergo surgical intervention.

CONCLUSION

OCT can be critical to diagnose macular conditions when retinal visualization is limited by asteroid hyalosis.

Detecting vitreomacular adhesions in eyes with asteroid hyalosis with triamcinolone acetonide

BACKGROUND

To report the incidence of posterior vitreous detachments (PVDs) and the surgical results of vitrectomy with intravitreal triamcinolone acetonide (TA) to detect vitreomacular adhesions in eyes with asteroid hyalosis (AH).

METHODS

Ten eyes of nine patients with AH underwent vitrectomy, six eyes with TA and four without TA. The presence of a PVD was determined preoperatively by ultrasound echography (USE) and intraoperatively by microscopic observations. The postoperative best-corrected visual acuities (BCVA) were evaluated.

RESULTS

The BCVA was improved by >2 Snellen lines in nine eyes and maintained at 20/20 with symptomatic improvements in the other eye. A vitreomacular adhesion was clearly seen during TA-assisted vitrectomy, and none was seen when TA was not used, even though preoperative USE showed an incomplete PVD in all eyes. The BCVA was not significantly better in eyes with TA-assisted vitrectomy than without TA-assisted vitrectomy. In one eye with vitrectomy without TA, a second surgery was required for a persistent cystoid macular edema and an epiretinal membrane. The BCVA and the edema in this eye improved after removing the epiretinal membrane.

CONCLUSIONS

All (ten) of the eyes with AH were found to have a vitreomacular adhesion by preoperative USE and intraoperative microscopic observations. The residual vitreous over the macula is more easily detected and removed after intravitreally injected TA, but the visual acuities were not significantly different from eyes without TA.

Indications de la vitrectomie chez les patients atteints d’une baisse d’acuité visuelle secondaire à une hyalopathie astéroïde

PURPOSE

Asteroid hyalosis is a vitreous degeneration with calcium and phosphorus--lipid complexes in elderly patients with vascular risk factors or general disease such as diabetes mellitus. Synchysis scintillans is a complication of pathological eyes. Generally there are no symptoms. This study aims to evaluate the role of vitrectomy in patients with a decrease in visual acuity.

CASE REPORTS

Pars plana vitrectomy was performed in three patients with visual acuity less than 1/10. The biomicroscope examination showed white and bright particles with rounded and variable shapes localized in the anterior vitreous, moving with the eye. The visualization of the fundus was difficult or impossible. On echography B, the vitreous was very dense with a complete posterior vitreous detachment. The vitrectomy was completed in one case by peeling an epiretinal membrane. Visual acuity was improved for two patients (6/10 or more) and stable for one patient with an atrophic DMLA.

DISCUSSION AND CONCLUSION

These results were compared with studies in the literature: in spite of complications, vitrectomy can be indicated in patients with a substantial decrease in visual acuity. However, the result is conditioned by the macular status. Fluorescein angiography can, when it is possible, evaluate the fundus before surgery.

Rétinopathie pigmentaire et hyalopathie astéroïde

Asteroid hyalosis is a rare degenerative condition of the vitreous. No causal relationship between retinitis pigmentosa and asteroid hyalosis has been established. We report a case of a 65-year-old male admitted for progressive hemeralopia. Visual acuities were 2/10e in the right eye and 4/10e in the left eye. Ophthalmic examination revealed a large number of asteroid and refringent bodies, a typical retinitis pigmentosa with a cystoid macular oedema confirmed by fluorescein angiography. Electrodiagnostic testing revealed an altered electroretinogram. Visual fields showed a typical generalized constriction. We discuss the clinical aspects and physiopathogenic mechanisms of this rare association through this case and other cases found in the literature.

The effect of pars plana vitrectomy in the management of Fuchs heterochromic cyclitis

PURPOSE

Fuchs heterochromic cyclitis (FHC) is characterized by a unilateral chronic iridocyclitis of insidious onset and uncertain cause. Our aim was to evaluate the effect of vitreous surgery in patients with FHC and clinically significant visual symptoms caused by inflammatory vitreous debris.

METHODS

This study was a review of 12 eyes of 12 consecutive patients with FHC who underwent pars plana vitrectomy for visually significant vitreous opacities. Cataract extraction with posterior chamber lens implantation had been performed on four eyes preoperatively. Four eyes had a concomitant lensectomy for cataracts, and one had a surgical posterior capsulotomy. Visual and anatomic data were recorded before surgery and for at least 6 months after surgery.

RESULTS

Visual acuity improved in all patients from an average logMAR of 0.57 to 0.007 (P = 0.0004) and by more than 2 Snellen lines in 8 of 12 of the eyes (P < 0.05). Symptoms of floaters resolved in all 11 patients in whom they were a symptom. Vitreous haze was cleared completely from an average Nussenblatt grade of 1.7 to 0 after 1 week (P = 0.0001).

CONCLUSIONS

Pars plana vitrectomy is a safe and effective treatment for the visual symptoms associated with FHC and can be combined safely with a lensectomy if required.

Nd:YAG vitreolysis and pars plana vitrectomy: surgical treatment for vitreous floaters

PURPOSE OF STUDY

To determine the efficacy of Nd:YAG vitreolysis and pars plana vitrectomy in the treatment of vitreous floaters.

METHODS

This is a single centre retrospective study of 31 patients (42 eyes) who underwent 54 procedures, Nd:YAG vitreolysis or pars plana vitrectomy, for the treatment of vitreous floaters between January 1992 and December 2000. Main outcome measures were percentage symptomatic improvement following treatment and incidence of post-operative complications. Statistical analysis was performed using the Fisher exact test.

RESULTS

Posterior vitreous detachment was the primary cause of floaters in all 42 eyes with co-existing vitreous veils in three eyes and asteroid hyalosis in two eyes. Thirty-nine of 42 eyes received Nd:YAG vitreolysis. Thirty-eight percent found Nd:YAG vitreolysis moderately improved their symptoms while 61.5% found no improvement. After an average of 14.7 months follow-up no post-operative complications were recorded. Fifteen eyes underwent a pars plana vitrectomy, one with combined phacoemulsification and posterior chamber implantation and 11 following unsuccessful laser vitreolysis. Pars plana vitrectomy resulted in full resolution of symptoms in 93.3% of eyes. One patient developed a post-operative retinal detachment which was successfully treated leaving the patient with 6/5 VA.

CONCLUSION

Patients' symptoms from vitreous floaters are often underestimated resulting in no intervention. This paper shows Nd:YAG vitreolysis to be a safe but only moderately effective primary treatment conferring clinical benefit in one third of patients. Pars plana vitrectomy, while offering superior results, should be reserved for patients who remain markedly symptomatic following vitreolysis, until future studies further clarify its role in the treatment of patients with floaters and posterior vitreous detachment.

Asteroid hyalosis

PURPOSE

This study evaluated ocular and systemic diseases in patients with asteroid hyalosis and compared axial lengths of asteroid hyalosis patients with the normal population.

METHODS

The examination of 26 patients with asteroid hyalosis consisted of complete history, complete ocular examination, blood pressure and laboratory studies in order to detect systemic diseases, A and B scan ultrasonography to measure axial lengths and to detect posterior vitreous detachment.

RESULTS

All patients had unilateral asteroid hyalosis; 10 (38.5%) were symptomatic. Eight patients (20.5%) had type II diabetes mellitus, 13 (33.3%) patients had systemic arterial hypertension and 7 (18%) had atherosclerotic heart disease; 5 (12.8%) had hyperlipidemia and 6 (15.4%) had hypercholesterolemia. Posterior vitreous detachment was found in 3 (11.5%) patients with asteroid hyalosis, and 6 patients in the control group (23.1%) had posterior vitreous detachment (p<0.01). In patients with asteroid hyalosis, the mean axial length difference between two eyes was 0.32 +/- 0.06, against 0. 10 +/- 0.02 in the control group (p<0.01).

CONCLUSION

Asteroid hyalosis may be found together with systemic diseases and such patients must be evaluated systematically for diabetes mellitus, hypertension and hyperlipidemia. Asteroid hyalosis can also cause artefactual lowering of axial length measurement, leading to significant error in calculations of intraocular lens power. This must be kept in mind before cataract surgery.