Macular translocation

Subretinal Injection Techniques for Retinal Disease: A Review

Inherited retinal dystrophies (IRDs) affect an estimated 1 in every 2000 people, this corresponding to nearly 2 million cases worldwide. Currently, 270 genes have been associated with IRDs, most of them altering the function of photoreceptors and retinal pigment epithelium. Gene therapy has been proposed as a potential tool for improving visual function in these patients. Clinical trials in animal models and humans have been successful in various types of IRDs. Recently, voretigene neparvovec (Luxturna^®) has been approved by the US Food and Drug Administration for the treatment of biallelic mutations in the RPE65 gene. The current state of the art in gene therapy involves the delivery of various types of viral vectors into the subretinal space to effectively transduce diseased photoreceptors and retinal pigment epithelium. For this, subretinal injection is becoming increasingly popular among researchers and clinicians. To date, several approaches for subretinal injection have been described in the scientific literature, all of them effective in accessing the subretinal space. The growth and development of gene therapy give rise to the need for a standardized procedure for subretinal injection that ensures the efficacy and safety of this new approach to drug delivery. The goal of this review is to offer an insight into the current subretinal injection techniques and understand the key factors in the success of this procedure.

Safety and efficacy of an intraocular Fresnel prism intraocular lens in patients with advanced macular disease: initial clinical experience

PURPOSE

To perform a pilot study of a new in-the-bag Fresnel prism intraocular lens (IOL) designed to deviate the image from diseased to healthy retina in eyes with bilateral age-related macular degeneration (AMD).

SETTING

Anterior segment subspeciality practice, Pretoria, South Africa.

DESIGN

Prospective nonmasked trial.

METHOD

Cataract surgery and unilateral implantation of the prismatic IOL were performed in patients with bilateral AMD and cataract. Outcomes were surgical complications, subjective and objective visual improvement, and undesirable optical effects.

RESULTS

Three eyes of 3 patients were evaluated. All patients reported displacement of the scotoma, and no patient reported diplopia. The only complication was posterior capsule opacification (1 eye).

CONCLUSIONS

Patients noted improved vision and no diplopia. This pilot was performed using a prototype IOL with single power and single angle of deviation; however, there is scope for individual patient optimization. This new technology merits further research and development because it may benefit large numbers of patients with stable end-stage AMD.

FINANCIAL DISCLOSURE

Dr. Claoué has a financial interest in the patent controlling the Fresnel prism IOL. Dr. Potgieter has no financial or proprietary interest in any material or method mentioned.

Macular translocation for neovascular age-related macular degeneration

BACKGROUND

Macular translocation has been proposed by vitreoretinal surgeons to displace the neuroretinal tissue onto healthy retinal pigment epithelium and choroid when the macula has been invaded by subretinal neovascularisation.

OBJECTIVES

This review aims at assessing the effectiveness of macular translocation for preserving or improving vision in patients with neovascular age-related macular degeneration (AMD).

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE and Caribbean Literature on Health Sciences (LILACS). There were no language or date restrictions in the search for trials.The electronic databases were last searched on 21 July 2008.

SELECTION CRITERIA

We included randomised or quasi randomised controlled trials comparing macular translocation with any other treatment or observation.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. The risk ratio (RR) of visual loss and visual gain was estimated at one year after treatment.

MAIN RESULTS

Only one small unblinded study on 50 people compared full macular translocation with photodynamic therapy (PDT) in AMD patients with predominantly classic subfoveal choroidal neovascularisation (CNV). At the last examination, performed in most of the cases after one year, there was no difference in the rate of visual loss of 3 or more lines (translocation versus PDT: RR 0.56, 95% confidence interval (CI) 0.22 to 1.43), as well as in the mean change of contrast sensitivity (1 letter favouring translocation; 95% CI -3.51 to 5.51) and the rate of recurrence of CNV (translocation versus PDT: RR 1.56, 95% CI 0.83 to 2.91). Other outcomes significantly favoured translocation, such as the gain of 3 or more ETDRS lines (RR 21, 95% CI 1.30 to 340.02), the mean change of visual acuity (mean difference (MD) 14.60, 95% CI 5.39 to 23.81) and the mean change of near visual acuity score (MD 17.80, 95% CI 3.98 to 31.62) which is obtained with an algorithm. Serious complications reported after macular translocation were retinal detachment in 6/25 patients and diplopia requiring prismatic correction in 5/25 patients.

AUTHORS' CONCLUSIONS

There is insufficient evidence from randomised controlled trials on the effectiveness of macular translocation, which is also not free of important risks. Furthermore, this technique is difficult to perform and a long surgical training is required. Future studies might include patients with small neovascular lesions that failed to respond to current pharmacological therapies and are willing to accept the risks associated with surgery to try to improve visual acuity.

Laser photocoagulation for neovascular age-related macular degeneration

BACKGROUND

Laser photocoagulation was the first treatment introduced to try to halt the progression of neovascular age-related macular degeneration (AMD), in which newly formed vessels or choroidal neovascularisation (CNV) grow under the macula leading to the occurrence of a scotoma or blind spot in the central visual field.

OBJECTIVES

The aim of this review was to examine the effects of laser photocoagulation for neovascular AMD.

SEARCH STRATEGY

We searched the CENTRAL, MEDLINE, EMBASE, LILACS, NRR and ZETOC in March 2007.

SELECTION CRITERIA

We included randomised trials of laser photocoagulation in people with CNV due to AMD.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. The risk ratio (RR) of severe visual loss (loss of six or more lines of visual acuity) was estimated at three months and two years after treatment.

MAIN RESULTS

Fifteen trials were included in the review (2064 participants). Three types of photocoagulation were used in the trials: direct photocoagulation of the entire CNV (11 trials), perifoveal photocoagulation (one trial) and grid photocoagulation (three trials). In 12 trials the control group was observation only. One trial compared photocoagulation to submacular surgery and two trials compared different lasers. Data on the progression of visual loss could be extracted from five of the eight trials of direct photocoagulation of the CNV versus observation. The treatment effect was in the direction of harm in all studies at three months follow up (RR 1.41, 95% confidence intervals (CI) 1.08 to 1.82). After two years the treatment effect was in the direction of benefit (RR 0.67, 95% CI 0.53 to 0.83). These studies were clinically heterogeneous with participants having CNV lesions in different locations and different baseline visual acuities. There was little evidence of statistical heterogeneity at three months but substantial statistical heterogeneity at two years. However, all treatment effects in the individual trials were in the direction of benefit. One study comparing perifoveal photocoagulation or observation of subfoveal CNV found benefits that were statistically significant only at two years (RR 0.36, 95% CI 0.18 to 0.72). Other comparisons did not demonstrate differences.

AUTHORS' CONCLUSIONS

In the medium to long term laser photocoagulation of CNV slows the progression of visual loss in people with neovascular AMD. However, it is associated with an increased risk of visual loss immediately after treatment and this period may be longer in people with subfoveal AMD. With the advent of modern pharmacological therapies, and concern for the impact of iatrogenic scotoma in subfoveal CNV, laser photocoagulation of subfoveal CNV is not recommended. No studies have compared photocoagulation with modern pharmacological agents for AMD for non-subfoveal CNV.