Implantable miniature telescope for vision loss due to end-stage age-related macular degeneration

What is the aim of this review?
We conducted this Cochrane Review to determine if the implantable miniature telescope (IMT) can improve vision in individuals with end-stage age-related macular degeneration (AMD). End-stage AMD refers to advanced AMD that is no longer treatable by standard medication or surgery.

Key messages
It is uncertain whether and how much the IMT can improve vision in individuals with end-stage AMD.

What was studied in this review?
AMD causes damage to the central part of the retina and results in loss of vision. AMD is a leading cause of uncorrectable blindness worldwide. Loss of vision results in loss of independence and reduced quality of life (e.g. reduced ability to read or drive). Since AMD is more common in older individuals, the number of affected individuals will increase significantly as the population ages.

The IMT is a device that is implanted in only one eye of a person with poor vision. Typically, it is implanted in the eye with better vision. The IMT works with the cornea (in the front of the eye) to enlarge what is seen and to focus images onto healthy parts of the retina (in the back of the eye). By helping the eye to send images to the healthy parts of the retina, the IMT may improve both near and distance vision and thus quality of life.

What are the main results of the review?
Because we found no study that matched our selection criteria, we cannot draw any conclusion about the effectiveness and safety of the IMT in people with end-stage AMD. Studies are needed that compare results in individuals who receive the IMT to results in individuals who do not receive the IMT. We found one ongoing study that is expected to be completed in 2020.

How up-to-date is this review?
The review authors searched for studies that had been published up to 2 November 2017.

Authors' conclusions: 

We found no RCT or quasi-RCT and can draw no conclusion about the effectiveness and safety of the IMT in improving visual acuity in individuals with late or advanced AMD. Since the IMT is typically implanted monocularly based upon which eye has better best-corrected distance visual acuity, randomization between eyes within an individual may not be acceptable. Studies are needed that compare outcomes between individuals randomized to the device versus individuals not implanted, at least during study follow-up, who serve as controls.

Read the full abstract...
Background: 

Age-related macular degeneration (AMD) causes progressive and irreversible damage to the retina, resulting in loss of central vision. AMD is the third leading cause of irreversible visual impairment worldwide and the leading cause of blindness in industrialized countries. Since AMD is more common in older individuals, the number of affected individuals will increase significantly as the population ages. The implantable miniature telescope (IMT) is an ophthalmic device developed to improve vision in individuals who have lost vision due to AMD. Once implanted, the IMT is used to enlarge objects in the central visual field and focus them onto healthy areas of the retina not affected by AMD, allowing individuals to recognize objects that they otherwise could not see. It is unclear whether and how much the IMT can improve vision in individuals with end-stage AMD.

Objectives: 

To assess the effectiveness and safety of the IMT in improving visual acuity and quality of life in people with late or advanced AMD.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 11); Ovid MEDLINE; Embase.com; PubMed; LILACS; AMED; Web of Science Conference Proceedings Citation Index-Science; OpenSIGLE; the metaRegister of Controlled Trials (mRCT) (last searched 27 June 2014); ClinicalTrials.gov; the ICTRP and the US Food and Drug Administration (FDA) Medical Devices database. The date of the search was 2 November 2017, with the exception of mRCT which is no longer in service.

Selection criteria: 

We planned to include randomized controlled trials (RCTs) and quasi-randomized trials that compared the IMT versus no IMT.

Data collection and analysis: 

Two review authors independently assessed all studies for inclusion, using standard methodological procedures expected by Cochrane.

Main results: 

Our search yielded 1042 unique records. We removed irrelevant studies after screening titles and abstracts, and evaluated five full-text reports from four studies; three were non-randomized studies. There was one ongoing RCT that compared the OriLens intraocular telescope with standard low vision training in eyes with end-stage AMD. Results for this study are expected in 2020.

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