Schwartz-Matsuo Syndrome

Etiology

Schwartz-Matsuo syndrome results from rhegmatogenous retinal detachment, causing an elevation in IOP through occlusion of aqueous outflow by photoreceptor outer segments, which have escaped through the retinal break and gained access to the anterior chamber. Therefore, the etiology is dependent on the risk factors for RRD.[2][4]

 The most common risk factors for RRD include: 

• Trauma
• History of retinal surgery
• Peripheral retinal breaks
• Lattice degeneration
• Pathologic myopia 
• History of cataract surgery 
• Family history of retinal detachment

Epidemiology

The sequelae of events in Schwartz-Matsuo syndrome are precipitated by RRD. Although the prevalence of RRD is high and has a bimodal age distribution (age 20 to 30 with high myopia vs. older population with posterior vitreous detachment), it doesn’t always lead to Schwartz-Matsuo syndrome.[5] The prevalence of Schwartz-Matsuo syndrome is quite low and only reported through case studies.

Pathophysiology

Several hypotheses have been proposed to explain the etiology of Schwartz-Matsuo syndrome. In 1973, Schwartz postulated iridocyclitis as the cause of increased IOP due to reduced outflow of aqueous humor.[3] 

However, Davidorf suggested that elevations in IOP occur due to blockage of the trabecular meshwork from pigmented granules released from retinal pigment epithelium during rhegmatogenous retinal detachment.[3][6] 

Finally, Matsuo et al. were able to isolate photoreceptor outer segments and inflammatory cells within the aqueous humor. This led him to hypothesize that photoreceptor outer segments and inflammatory cells were able to escape the subretinal space and communicate with the aqueous humor potentially through the retinal tear. This eventually leads to the accumulation of photoreceptor outer segments in the trabecular meshwork and aqueous outflow obstruction, causing elevated intraocular pressures.[3]

Aqueous humor is a clear intraocular fluid secreted by the ciliary epithelium lining the ciliary processes and is mainly responsible for the structural integrity and maintenance of normal intraocular pressure of the eye.[7][8] 

Normally, aqueous humor flows from the posterior chamber (PC) of the eye to the anterior chamber (AC) through the pupil and gets reabsorbed via two pathways – the conventional pathway involving the trabecular meshwork and the non-conventional route involving the uveoscleral pathway. Usually, the rate of aqueous humor production and reabsorption is at equilibrium regulating intraocular pressure.[7][8] 

In Schwartz-Matsuo syndrome, the conventional pathway consisting of the trabecular meshwork is blocked by photoreceptor outer segments disrupting normal aqueous outflow and resulting in an elevation in IOP.

Typically, retinal detachment results in hypotony (low intraocular pressure). Several factors, including the type of detachment, duration, and extent, influence the degree of hypotony.[9][10] 

Several hypotheses have been postulated in the past regarding the pathophysiology behind the low intraocular pressure seen in retinal detachment. However, it is now believed that drainage of subretinal fluid via the peri-optic connective tissue is responsible for the low intraocular pressure seen in retinal detachment, a mechanism different from the one seen in Schwartz-Matsuo syndrome.[10] 

Therefore, an exam finding of elevated intraocular pressure in patients with retinal detachment is unusual and should raise suspicion and warrant further workup for Schwartz-Matsuo syndrome.

History and Physical

Schwartz-Matsuo syndrome presents with symptoms related to increased IOP, including eye pain, photophobia, blurred vision, headache, nausea, or vomiting. Important information in the history should also include symptoms related to retinal detachment, including a history of ocular trauma, recent surgery, floaters, photopsia, peripheral visual field loss, or decreased visual acuity.

Although the most common cause of rhegmatogenous retinal detachment is non-traumatic, blunt ocular trauma to the eye may lead to Schwartz-Matsuo syndrome.[11] In fact, a retrospective study involving a series of patients with retinal breaks following blunt ocular trauma found that 84% of patients develop rhegmatogenous retinal detachment.[12][13] 

Typically, there are two mechanisms through which blunt ocular trauma can result in retinal detachment – one is from contusion to the globe, whereas the other is a consequence of a perforating injury to the posterior segment of the eye.[12]

Retinal detachment following traumatic contusion usually results from a direct blow to the globe of the eye. These usually result in two types of retinal breaks: retinal dialysis (typically located in the superonasal and inferotemporal quadrant) and large, irregular breaks at the level of the equator.[12] Retinal dialysis is a tear in the retina where the anterior edge is at the ora serrata, and the posterior edge is at the vitreous base. 

The retinal detachment that results from a traumatic perforation of the posterior segment of the eye requires urgent management at the time of diagnosis. This type of traumatic injury is not likely to appear similarly to Schwartz-Matsuo syndrome as the intraocular pressure is usually lower.[12]

Closed ocular traumas with contusions that lead to retinal detachment often are not accompanied by acute symptoms making them difficult to diagnose at the time of injury. Several reasons, including delayed symptom presentation, waiting to seek medical attention, and other distracting injuries, add to the delay in prompt ophthalmic evaluation.[13] Therefore, obtaining a thorough and accurate history at the time of presentation is important and can significantly impact future outcomes.

Furthermore, history should include an assessment of other etiologies of increased IOP such as a family history of glaucoma in a first-degree relative, history of ocular hypertension, history of intraocular surgery, intraocular inflammation, refractive error, pertinent medical history including cardiovascular disease, hypertension, diabetes mellitus, chronic use of topical/systemic corticosteroids, and other medications.[14]  

As Schwartz-Matsuo syndrome may appear similar to uveitis or uveitic glaucoma, history should also be taken to evaluate for uveitis or intraocular inflammation. The history may include prior episodes of ocular hyperemia, photophobia, eye pain, excessive tearing, and decreased visual acuity. It is also important to identify and rule out other systemic inflammatory diseases, including inflammatory bowel disease, ankylosing spondylitis, reactive arthritis, psoriatic arthritis, sarcoidosis, systemic lupus erythematosus, syphilis, tuberculosis, and HIV/AIDS that could present with ocular pain and uveitis.[15] 

Signs of uveitis include white blood cells and flare in the anterior chamber. Anterior uveitis is also associated with iris nodules, keratic precipitates (granulomatous and non-granulomatous), pigment on the anterior lens capsule, and posterior synechiae. These findings are typically not present in Schwartz-Matsuo syndrome. In particular, there are some causes of uveitis that are associated with high IOP.

Acute uveitis secondary to toxoplasmosis, herpes simplex virus, varicella-zoster virus, cytomegalovirus, sarcoidosis, syphilis, and Posner-Schlossman syndrome are associated with increased IOP. Mechanisms of increased IOP in uveitis are hypothetically caused by the deposition of inflammatory proteins and cells within the trabecular meshwork, trabeculitis leading to outflow obstruction, or increased aqueous humor production.[16]

Therefore, it is essential to evaluate for other possible causes of increased IOP in patients presenting with symptoms related to anterior uveitis as it is an important differential diagnosis of Schwartz-Matsuo syndrome.

The examination should include an IOP measurement, a slit-lamp examination including gonioscopy, and a dilated fundus examination with scleral depression to evaluate for rhegmatogenous retinal detachment, including evidence of retinal dialysis. It is important to perform a slit lamp and gonioscopic examination to rule out other causes of elevated IOP. Findings such as peripheral anterior synechiae and neovascularization of the angle would suggest an alternative etiology for elevated IOP. 

Typically, angle changes associated with angle recession are seen on the gonioscopic exam in patients with blunt trauma to the eye, which can also be a risk factor for retinal detachment. Therefore, it's important to understand that both angle recession and retinal detachment can occur simultaneously in patients with blunt trauma to the eye leading to Schwartz-Matsuo syndrome.

A triad of elevated IOP, rhegmatogenous retinal detachment and aqueous cells in the anterior chamber allows for the diagnosis of Schwartz-Matsuo syndrome.[1][17][18]

Evaluation

Schwartz-Matsuo syndrome is primarily a clinical diagnosis; however, definitive diagnosis requires cytological evaluation with a demonstration of photoreceptor outer segments in the anterior chamber using transmission electron microscopy (TEM).[3] Electron micrograph of the anterior chamber in Schwartz-Matsuo syndrome often shows pigmented granules and cellular fragments with multiple cell membrane layers in the trabecular meshwork.[19] 

Further analysis of a rod outer segment under TEM shows lobules containing rod sacs. Each rod sac has two thick membranes with a less dense inner space.[20] On the other hand, an electron micrograph of a cone outer segment lacks lobules, but each pile of cone sac is visualized with a continuous fold of membrane.[20]

Despite that, many practices and hospitals lack access to a transmission electron microscope. Therefore, modern slit lamps with monochromatic filters can aid in characterizing the various types of cells (such as white blood cells, red blood cells, pigment cells, or photoreceptors) that may be present in the anterior chamber to further support the diagnosis of Schwartz-Matsuo syndrome.

The widely used red-free filter or “green” filter is especially useful when examining patients with Schwartz-Matsuo syndrome. This filter usually has an optical wavelength between 540 nm to 570 nm making blood and blood vessels appear dark and well-defined with enhanced contrast.[21] 

The green filter also allows for the visualization of white blood cells in the anterior chamber. In situations where red blood cells and/or pigmented cells are the predominant cells in the anterior compartment, using the red-free filter accentuates the visibility of white blood cells while minimizing the visibility of RBCs and pigmented cells. Photoreceptors also contain visual pigment embedded in their cell membrane folds, thus allowing for less visualization under the green filter.[22]

Treatment / Management

The definitive treatment for Schwartz-Matsuo syndrome is surgical reattachment of the retina by retinopexy, scleral buckle, or pars plana vitrectomy and washout of anterior compartment cellular debris.[1][23](B3)

Due to the rarity of the disease, outcomes associated with Schwartz-Matsuo syndrome have not been investigated. Although medical management with prostaglandin agonists, beta-blockers, selective alpha-2 receptor agonists, or topical carbonic anhydrase inhibitors can be used to lower intraocular pressure while awaiting surgical intervention, its efficacy remains in question.[24] 

However, surgical reattachment has been shown to normalize IOP and preserve further vision loss in patients with Schwartz-Matsuo syndrome.[3] Corticosteroids have no role in the treatment of Schwartz-Matsuo syndrome.[17](B3)

Differential Diagnosis

The differential diagnosis for Schwartz-Matsuo syndrome includes several other conditions.[1][3] These include:

• Open-angle glaucoma
• Anterior uveitis
• Posner-Schlossman syndrome
• Uveitic glaucoma
• Cluster headache

Prognosis

Early detection of disease and prompt management of increased IOP and retinal detachment is essential for a good outcome. Successful surgical reattachment of the retina can decrease IOP by preventing further communication between the subretinal space and aqueous humor, aiding in a better prognosis. Often, the prognosis is good with timely surgical intervention.

Complications

Complications in Schwartz-Matsuo syndrome arise secondary to acute elevations in IOP and retinal detachment. A significant increase in IOP can lead to visual loss and blindness complicated by glaucoma requiring further medical or surgical intervention.[1]