Laser treatment of drusen to prevent progression to advanced age-related macular degeneration

Abstract

Background Drusen are amorphous yellowish deposits beneath the sensory retina. People with drusen, particularly large drusen, are at higher risk of developing age-related macular degeneration (AMD). The most common complication in AMD is choroidal neovascularisation (CNV), the growth of new blood vessels in the centre of the macula. The risk of CNV is higher among people who are already affected by CNV in one eye. It has been observed clinically that laser photocoagulation of drusen leads to their disappearance and may prevent the occurrence of advanced disease (CNV or geographic atrophy) associated with visual loss. Objectives To examine the effectiveness and adverse effects of laser photocoagulation of drusen in AMD. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 7), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2015), EMBASE (January 1980 to August 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to August 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 3 August 2015. Selection criteria Randomised controlled trials (RCTs) of laser treatment of drusen in AMD in which laser treatment had been compared with no intervention or sham treatment. Two types of trials were included. Some trials studied one eye of each participant (unilateral studies); other studies recruited participants with bilateral drusen and randomised one eye to photocoagulation or control and the fellow eye to the other group. Data collection and analysis Two review authors independently selected studies and extracted data. We pooled data from unilateral and bilateral studies using a random-effects model. For the bilateral studies, we estimated the within-person correlation coefficient from one study and assumed it was valid for the others. Main results The update of this review found two additional studies, totaling 11 studies that randomised 2159 participants (3580 eyes) and followed them up to two years, of which six studies (1454 participants) included people with one eye randomised to treatment and one to control. Studies were conducted in Australia, Europe and North America. Overall, the risk of bias in the included studies was low, particularly for the larger studies and for the primary outcome development of CNV. Photocoagulation did not reduce the development of CNV at two years’ follow-up (odds ratio (OR) 1.07, 95% confidence interval (CI) 0.79 to 1.46, 11 studies, 2159 participants (3580 eyes), high quality evidence). This estimate means that, given an overall occurrence of CNV of 8.3% in the control group, we est...

Investigations into localized re‐treatment of the retina with a 3‐nanosecond laser

“…It would have been ideal to have taken multifocal electroretinogram measurements after each laser application in order to assess preservation of retinal function at the site of treatment. Recent work using the 1.7 ms pulse duration SRT laser, which induces an RPE-specific response analogous to that of the 2RT laser [10,25], showed that subvisual SRT caused histological changes of the same magnitude as documented by subvisual 2RT in the current study, and negligible functional changes when assessed by multifocal electroretinogram [42]. Thus, it is reasonable to predict that since repeat 2RT laser did not induce histological damage additive to that of single application, then functional impairment would likewise not have increased.…”

“…Results to date have shown no clinically visible lesions or disease progression, reduced drusen load, and an improvement in flicker threshold [13,18]. It has been known for over 40 years that laser photocoagulation reduces drusen load in patients with AMD [19], but data pertaining to the risk of inducing exudative lesions have been contradictory [20][21][22][23][24][25]. The divergent results are believed to be related to the number and intensity of the laser burns, and the study inclusion criteria.…”

Nanosecond Laser Treatment for Age-Related Macular Degeneration Does Not Induce Focal Vision Loss or New Vessel Growth in the Retina

“…Thermal laser photocoagulation with continuouswave (CW) lasers was used in the 1990s and it was reported to reduce drusen load, a risk factor for progression to late-stage AMD. [10][11][12][13][14] However, these lasers result in thermal damage to the photoreceptors and inner retinal neurons, as the laser energy is converted to heat energy through absorption by the melanin in the RPE monolayer and choroid. 15,16 Some reports have also highlighted a potential increased risk of CNV, subretinal fibrosis, and microscotomas.…”

“…[17][18][19][20] A Cochrane review of the literature for thermal laser treatments for AMD suggests that the frequency of CNV in AMD eyes is not different between laser-treated and the natural history cohorts when laser energy is within the clinical range. 10 However, when used at high-energy levels in mice, the thermal laser burn can break Bruch's membrane, leading to the growth of new choroidal vessels into the subretinal space, mimicking the neovascular form of human AMD. 21 Because of this, photocoagulation lasers are being used at high energy to induce a model of CNV in various animals, 21 and further use of thermal lasers for prophylactic treatment for early stages of AMD has not been continued.…”

A Novel Nanoparticle Mediated Selective Inner Retinal Photocoagulation for Diseases of the Inner Retina

“…Retinal neovascularization exhibits two types of vessel growth: (i) vessel sprout in the anterior part of the retina and NFL, sometimes breaking through ILM and invading the vitreous, and (ii) vessel growth in the posterior direction, through outer retina towards sub-retinal space [3, 9, 10]. Laser based retinal photocoagulation is a clinically established non-invasive treatment procedure for diabetic retinopathy [11, 12]. …”