Visual floaters – described by their symptoms of tiny specks, circles and shadows that appear in a patient’s field of vision – become increasingly prevalent with age due to the degenerative vitreous changes that occur throughout life. In youth, hyaluronan ensures that the collagen fibrils remain separated in the vitreous cavity, maintaining the transparency of the vitreous. However, with time, this hyaluronic acid dissociates from collagen, causing cross-linking and aggregation of collagen with fibrous structures that scatter light—a process known as vitreous liquefaction.
Clinically, a posterior vitreous detachment (PVD) is often marked by a degree of fibroglial tissue known as a Weiss ring that is free floating over the optic nerve. A PVD allows the vitreous body to move when the head or eye moves, and thus, the Weiss ring and vitreous opacities cast shadows onto the retina that are perceived as floaters.
A PVD is present in approximately 65% of patients reaching the age of 65 years. Although most patients grow accustomed to the visual disturbance associated with Weiss rings and other floaters, many patients find them bothersome due to various factors including a reduction in contrast sensitivity which affects their quality of life.
Three management options currently exist for patients presenting with symptomatic floaters:
• For patients who find that the floaters are not really impacting their quality of life, a Non-Invasive “learning to live with floaters” management plan focusing on patient education and observation may be the best option.
• The second option for symptomatic patients would be a surgical option known as a pars plana vitrectomy (PPV) with either a 1-incision intrector or a standard 3-port vitrector.
• The third option currently available for patients is laser vitreolysis, also referred to as Laser Floater Removal (LFR) or YAG vitreolysis.
YAG vitreolysis is a minimally invasive treatment option that involves the use of an extremely precise nano-pulse YAG laser which safely vaporizes eye floaters and breaks apart large floaters into smaller, less noticeable pieces. Laser floater removal is currently a relatively new technology, but more and more doctors are beginning to specialize in this procedure.
YAG vitreolysis for treatment of floaters was recently tested in a single-center, masked, sham-controlled randomized clinical trial, conducted at Ophthalmic Consultants of Boston, Massachusetts, USA.1 The study included 52 of the practice’s patients with symptomatic Weiss rings: 36 patients were randomly assigned to unilateral treatment with YAG laser vitreolysis, and 16 were assigned to sham YAG vitreolysis (control). The mean (SD) age of participants was 61.4 (8.0) years in the YAG group and 61.1 (6.6) years in the sham group.
In all cases, one eye (the eye with the most patient-determined floater-related symptoms) was treated, and the other eye was observed. Patients were assigned to the YAG and sham groups in a 2:1 ratio to maximize the number of treated patients and to obtain more robust efficacy and safety data for YAG vitreolysis.
After intraocular pressure was measured, the pupil of the study eye was dilated with phenylephrine, 2.5%, and tropicamide, 1%. Proparacaine was given, and an ocular karickhoff 21 mm vitreous lens with goniosol was applied before YAG laser administration. The number of laser shots given per patient was at the discretion of the treating physician, but in all cases, laser application ceased after vaporization of the Weiss ring and all other visually significant floaters. The 36 eyes treated with YAG laser vitreolysis (69% phakic) received a mean of 218 laser shots with a mean power of 1316 mJ.
YAG vitreolysis was performed using the Ultra Q Reflex laser (Ellex Medical Lasers, Adelaide, Australia). A maximum energy per pulse of 7 mJ was used, as described by Tsai et al.2 The energy was initially set at 3 mJ and titrated to an appropriate level at which the surgeon observed plasma formation with the creation of gas bubbles.
Patients received only one laser treatment session to prevent unmasking of controls. Participants in the sham group underwent similar treatment; they were fitted with a sham lens that had a lens filter glued to the surface to prevent YAG energy from passing through the lens. The YAG laser energy was at its lowest setting of 0.3 mJ. Patients were not asked to which group they believed they were randomized.
All patients were followed up for 6 months with clinical examinations held at week 1, month 1, 3 and 6. Objective masked grading of color photography found that 34 of 36 patients (94%) in the YAG group had significantly improved or completely resolved floaters as compared with 0 out of 16 patients in the sham group. Patients in the YAG group reported significantly greater improvement in self-reported floater-related visual disturbance (54%) compared with sham controls (9%). 19 of 36 patients (53%) in the YAG group reported their symptoms as significantly or completely better after treatment as compared to 0 out of 16 in the sham group. The YAG group also reported significantly better general vision and peripheral vision with fewer role and dependency on others than the sham controls at 6 months.
No adverse events judged to be of clinical relevance occurred after YAG laser vitreolysis in this small prospective study, which was underpowered to identify less common potential complications. However, with use of the rule of 3, there is 95% confidence that there is no greater than a 1 in 12 (8.3%) risk of a serious adverse event after YAG vitreolysis.
For patients presenting with visual disturbance secondary to a clinically confirmed Weiss ring, the current study suggests that YAG vitreolysis improves short-term visual outcomes, both subjectively and objectively, without adverse events judged to be clinically relevant.
“This pilot study shows encouraging results after YAG vitreolysis for symptomatic Weiss ring floaters. Further research is needed, particularly with larger clinical trials of longer duration that include multiple floater types so that we may better understand the efficacy and safety of YAG vitreolysis,” explained Dr. Shah.
References:
1 Shah CP, Heier JS. YAG Laser Vitreolysis vs Sham YAG Vitreolysis for Symptomatic Vitreous loaters: A Randomized Clinical Trial. JAMA Ophthalmol. 2017;135(9):918-923. 2 Tsai WF, Chen YC, Su CY. Treatment of vitreous floaters with neodymium YAG laser. Br J Ophthalmol. 1993;77(8):485-488.
