New Horizons in the Treatment of Vitreous Floaters

Overview

The Ultra Q Reflex® (Ellex) constitutes the only Nd:YAG laser approved for the treatment of vitreous floaters. No randomized controlled clinical trial has been carried out to this day in order to investigate its superiority over sham treatment. In the present study, 60 eyes will be randomized and blinded into 2 groups, one receiving up to two sessions of laser vitreolysis the other scheduled for two sessions of sham treatment. After a maximum of two (sham) treatment sessions (1 per month), patients' utility value score and BCVA will be re-assessed. A follow-up period of 12 months (with visits at month 1, 6 and 12 post-treatment) will ensue the "treatment phase" to register any late adverse events that may be associated with laser vitreolysis. As vitrectomy constitutes a highly invasive procedure, which must therefore be restricted to severe cases only, laser vitreolysis may present a valuable treatment option for patients with moderate vitreous floaters that are not eligible for vitrectomy.

A great number of patients seek out their ophthalmologists when troubled by vitreous floaters. The majority of these patients are reassured when the diagnosis is made and are content to get accustomed to these "mouches volantes". A considerable proportion, however, feels permanently irritated by vitreous floaters which may result in a significant decrease of patients' quality of life. Until recently, pars plana vitrectomy constituted the only established therapeutic option. Though a standard surgical procedure, the potential adverse events associated with vitrectomy are not negligible and patients must allow for an extended period of visual rehabilitation. Therefore, treatment was restricted to severe cases and thus only a very small percentage of patients received any treatment at all. Reports exist on Q-switched Nd:YAG laser surgery for vitreous opacities, membranes and vitreoretinal bands in 59 eyes. The results of early laser vitreolysis are sobering with an improve in visual acuity in only 18 eyes but considerable adverse events such as retinal holes with detachment (1 eye), minor retinal hemorrhages (4 eyes) and focal opacities of the crystalline lens (5 eyes). According to another study, the Q-switched system allowed treatment of a wider variety of indications in the posterior pole and requires fewer sessions when compared to a mode-locked system. Due to the higher energy levels required by Q-switch system, however, complications occurred more frequently. An additional study presented more favorable results; in all 15 cases the symptoms of vitreous floaters disappeared after treatment and no adverse events were reported during a follow-up period of at least 1 year. Nevertheless, the reported energy levels (5-7.1mJ and total energy 71-742mJ) were considerable. Further results suggested that laser vitreolysis moderately improved symptoms in 38% of all patients, while 61,5% registered no improvement; no adverse events were reported. In contrast, vitrectomy resulted in full resolution of symptoms in 93,3% of eyes - with one patient suffering post-operative retinal detachment. A recent study presented 3 cases of chronic open-angle glaucoma secondary to ND:YAG vitreolysis (3 eyes of 2 patients). The latency period between vitreolysis and onset of elevated IOP ranged from 1 week to 8 months; other potential factors promoting a rise in IOP, namely "inflammation, steroid use, or other identifiable causes" are reported as absent. In two eyes, SLT followed by glaucoma surgery (Trabectome) was required to stabilise IOP. Whereas the treatment of floaters located in the anterior vitreous resulted in no obvious change, treatment in the mid-vitreous and posterior vitreous lead to an increase in protein, the refractive index and the viscosity of the vitreous humor. It appears that the current literature remains inconclusive as to the efficacy and safety of Nd:YAG vitreolysis. In the review literature, floater vitrectomy - especially with small sutureless gauge instruments and a corevitrectomy - yields excellent success rates combined with a low risk profile. In contrast, the efficacy of vitreolysis ranges between 0 and 100%. The key factor to success in vitreolysis is the use of appropriately high energy levels and the application of a sufficient amount of shots. In his retrospective, observational study (including 168 eyes, treatment with the Ultra Q Relfex®) 92% of patients were satisfied with the result; In the present study, vitreolysis is performed with the Ultra Q Reflex® laser - to this day the only laser officially approved for vitreolysis. It features an ultra-Gaussian beam mode, teamed with a fast-pulse rise time and a small-spot size. Due to the tightly controlled plasma with its higher power density fewer shots are required which results in a lower cumulative dose. Moreover, the co-axial alignment of the practitioner's vision, the target illumination, and the treatment beam grants better illumination of vitreous opacities and thus allows for more precise focusing. This patented design facilitates the vaporization of floaters and minimizes the risk of collateral damage to adjacent tissues.