Other Complications of Posterior Vitreous Detachment
In some patients, the process of PVD is incomplete and leads to secondary complications. Residual attachment of PHM in the macular region may result in vitreomacular traction syndrome or epiretinal membrane formation. In the former, the attached premacular PHM is still continuous with the rest of the detached PHM. If there is complete dehiscence of the premacular PHM, however, it may then manifest as an epiretinal membrane.[11,12,13] A corresponding defect in the detached PHM can usually be seen. A recent histological study confirmed that the premacular membranes share similar characteristics with PHM (presence of type IV collagen and laminocytes).[44] In contrast to PHM, however, some membranes demonstrated increased cellularity and reduplication of type IV collagen. Reduplication may explain the reported presence of a double layer of membrane during membrane peeling of the macula in some cases.
Not all eyes with PHM defects exhibit clinically obvious epiretinal membranes.[13] Epiretinal membranes are more likely to form with coexisting ocular pathologies, such as retinal tears and retinal vascular diseases.[44,45,46] Activation of the laminocytes may play an important role in the formation of clinically apparent epiretinal membranes.
Incomplete separation of the PHM can also occur in patients who develop proliferative retinal disease, the most common example being proliferative diabetic retinopathy. In such cases, neovascular complexes peg the PHM to the retina and may result in tractional retinal detachments as the PHM attempts to pull away from the retina. The management of these complications is outside the realm of this paper.
In patients with recent PVD, peripheral retinal examination is mandatory. Urgent examination, preferably within 24 to 48 hours, is warranted for patients at risk of rhegmatogenous complications. This risk includes symptoms that suggest the possibility of vitreous hemorrhage or retinal detachment (e.g., visual field defect) and myopia; it also includes past history of retinal tear or detachment in the fellow eye or family history of retinal tear or detachment. Other cases should be examined within 6 weeks.
Apart from the history of presenting symptoms and past ophthalmic history, it is also important to note the past medical history of the patient. Various systemic conditions may predispose the patient to vitreous hemorrhage (e.g., diabetes mellitus, sickle cell disease, vasculitis) or retinal breaks (e.g., Stickler syndrome).
Examination of the eye should be performed through dilated pupils. All patients require slit-lamp biomicroscopy and indirect ophthalmoscopy with scleral depression if necessary to view the retina out to the ora serrata. The use of noncontact slit-lamp examination alone may lead to retinal breaks being missed.[47] Assessment of the vitreous should be performed as described above. Where vitreous hemorrhage is obscuring part of the fundal view (usually inferiorly) and the retina can be seen to be attached, then regular weekly examinations are needed until adequate visualization can be obtained. Symptoms of retinal detachment should be explained clearly to the patient together with instructions to seek medical attention if these develop.
Signs found to be significantly associated with increased risk of retinal tears in eyes with PVD (and without previous trauma or intraocular surgery) include numerous anterior vitreal cells, pigment granules, and macroscopic vitreous or preretinal hemorrhage.[34,48,49]
If on initial examination adequate visualization of the retina is possible, and no complications have been found, then most patients can be discharged from the clinic. As has been mentioned previously, progression of PVD may cause tears at a later time.[36] Although it is not possible to predict which patients will be in this category, a recent study suggested that those who presented with multiple floaters, curtain, or cloud as initial presenting symptoms or later developed an increase in floaters after initial consultation should be scheduled for reexamination.[37]
If the fundal view is completely obscured, testing for a relative afferent pupillary defect and ability to accurately localize light shining into the eye (light projection) provides useful information about the status of the retina. B-scan ultrasonography is also useful under such circumstances to look for the presence of retinal detachment or large tears, but not small tears. Conservative management with regular weekly examination and Bscan of the eye is acceptable if there is low suspicion of retinal breaks. Surgery can be considered for visual reasons (e.g., patient's only eye), nonclearing hemorrhage (after 3 months), or for other reasons (e.g., ghost cell glaucoma).
The presence of any additional risk factors, either from the history or examination (e.g., pigment granules in vitreous), is highly significant. In such cases, urgent vitrectomy is indicated (Figure 7 and Figure 8). Reviewing the patient regularly while waiting for the hemorrhage to clear spontaneously may result in unnecessary delays, adversely affecting the final visual prognosis of the eye if a retinal detachment involving the macula was to develop.
Algorithm 1. Management of acute posterior vitreous detachment.
Algorithm 2. Management of posterior vitreous detachment.
It is important to examine the fellow eye for the presence of a PVD, even if it is asymptomatic, due to the possibility of occult PVD and retinal tears. There is also the tendency for complications in the fellow eye to mirror that of the index eye.[29] Therefore, patients with unilateral PVDs complicated by retinal tears or detachment should present themselves urgently when symptoms suggestive of PVD develop in the fellow eye. This has been found to occur within 3 years of the first eye in most patients.[50]
© 2005 Comprehensive Ophthalmology Update, LLC
Cite this: Posterior Vitreous Detachment: Current Concepts and Management - Medscape - Jul 01, 2005.
