Age related macular degeneration
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Age related macular degeneration (AMD) is a major cause or mechanism of loss of vision it comes in two types, classified as "dry" and "wet", the latter involving visible new growth of blood vessels forward through the retina. Dry macular degeneration lacks good treatment.
Contents |
Classification
| AMD Category | Definition | AMD Group | Clinical |
|---|---|---|---|
| 1 | No drusen or nonextensive small drusen only in both eyes | 1 Normal | Unremarkable fundi |
| 2 | Extensive small drusen, nonextensive intermediate drusen, or pigment abnormalities in at least one eye | 2 Early AMD | |
| 3 | Large drusen, extensive intermediate drusen, or noncentral geographic atrophy in at least one eye | 3 Intermediate AMD |
|
| 4 | Advanced age-related macular degeneration, or visual acuity less than 20/32 attributable to lesions of nonadvanced age-related macular degeneration, such as large drusen in the fovea, in only one eye | ||
| Some 4 and a few 3 | 4 Geographic Atrophy : Advanced non-vascular AMD |
| |
| Some 4 | 5 Neovascular: Advanced neovascular AMD |
|
Risk factors
- Age
- White race
- Family history
- Up to 75% explained by compliment system genetic variability[2]
- Polymorphisms in age-related maculopathy suscetibility 2 (ARMS2) gene
- Homozygous CFH (Tyr402His) and ARMS2 (Ala69Ser) combined increases risk 60 times[3]
- Conflicting evidence exists for the SERPING1 gene but the associations claimed look to be clinically insignificant[4]
- Smoking
- More than 10 pack years
- High intake vegetable fat
- Low intake/plasma levels:
- Antioxidants
- Zinc
General treatment
- Stop smoking
- Increase dietary antioxidants and consumption of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)[5]
- Control hypertension
- Control obesity
Dry macular degeneration
Common but does not have rapid progression to effective blindness
Treatment
- Antioxidant vitamin and zinc supplementation is likely to be beneficial for moderate to severe AMD if used in the formulation of the AREDS trial.[6][7]. However the effect on mortality might lead to net population harm[8] and there should be no question that vitamins as used in AREDS are not the way forward for primary prevention of AMD.
- If smoker the vitamin mix should best not contain β-carotine due to possible malignancy risk[9]
- Further the β-carotine component is suspected by subsequent analysis of nutritional data from the AREDS trial recruits to have no diet related association with AMD progression[10] so it could be argued might only add to risk. This issue will be examined in AREDS2 which has finished recruiting but will not report 5 to 6 year data until 2014.
- The association with decreased rate of progression and higher omega-3 fatty acid intake has not yet been convincingly shown to be relevant to treatment in an intervention trial but is worth noting in advice to an individual[5]
- Laser to drusen is unknown effectiveness
Wet macular degeneration
Rarer but now should be regarded as an urgent opthalmology referral, certainly where photodynamic or ranibizumab (or equivalent) therapy might be possible. Can in simple terms be regarded as the transition of dry macular degeneration to condition of neovascularistion that is rapidly progressive over months. The commonest cause of blind registrations in UK.
Treatment
- Photodynamic treatment with verteporfin is is beneficial
- Thermal laser photocoagulation is trade off between benefits and harms
- External beam radiation is of unknown effectiveness
- VEGF inhibitors
- Ranibizumab is beneficial and the only therapy to conclusively increase visual acuity for periods up to 2 years.
- Pegaptanib is of moderate effectiveness and although first to market has poorer evidence base even if beneficial
- Bevacizumab is likely to be beneficial but the manufacturer (who also manufactures ranibizumab) is not undertaking further pre licensing developmemt. Clinical trials are being undertaken independent of industry due to considerable potential cost saving if effective.
External links
- 2000 The Royal College of Ophthalmologists' guideline on age related macular degeneration.
- NEJM review article on age-related macular degeneration.[11]
- TA68 NICE Guidance on photodynamic therapy (PDT) to treat age-related macular degeneration (ARMD) (2003)
- Macular degeneration (age-related) - pegaptanib and ranibizumab: Appraisal consultation June 2007
References
- ↑ Risk factors associated with age-related macular degeneration. A case-control study in the age-related eye disease study: Age-Related Eye Disease Study Report Number 3. Ophthalmology. 2000 Dec; 107(12):2224-32.
- ↑ Jager RD, Mieler WF, Miller JW. Age-related macular degeneration. The New England journal of medicine. 2008 Jun 12; 358(24):2606-17.(Link to article – subscription may be required.)
- ↑ Jager RD, Mieler WF, Miller JW. Age-related macular degeneration. The New England journal of medicine. 2008 Jun 12; 358(24):2606-17.(Link to article – subscription may be required.)
- ↑ Allikmets R, Dean M, Hageman GS, Baird PN, Klaver CC, Bergen AA, Weber BH. The SERPING1 gene and age-related macular degeneration. Lancet. 2009 Sep 12; 374(9693):875-6; author reply 876-7.(Link to article – subscription may be required.)
- ↑ a b Chiu C, Klein R, Milton RC, Gensler G, Taylor A. Does eating particular diets alter risk of age-related macular degeneration in users of the age-related eye disease study supplements? Br J Ophthalmol. 2009 doi:10.1136/bjo.2008.143412
- ↑ A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Archives of ophthalmology. 2001 Oct; 119(10):1417-36.
- ↑ Tan JS, Wang JJ, Flood V, Rochtchina E, Smith W, Mitchell P. Dietary Antioxidants and the Long-term Incidence of Age-Related Macular Degeneration The Blue Mountains Eye Study. . 2007 Jul 28.(Epub ahead of print) (Link to article – subscription may be required.)
- ↑ Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane database of systematic reviews (Online). 2008; (2):CD007176.(Epub) (Link to article – subscription may be required.)
- ↑ Omenn GS. Chemoprevention of lung cancers: lessons from CARET, the beta-carotene and retinol efficacy trial, and prospects for the future. European journal of cancer prevention : the official journal of the European Cancer Prevention Organisation (ECP). 2007 Jun; 16(3):184-91.(Link to article – subscription may be required.)
- ↑ Chiu CJ, Milton RC, Klein R, Gensler G, Taylor A. Dietary compound score and risk of age-related macular degeneration in the age-related eye disease study. Ophthalmology. 2009 May; 116(5):939-46.(Link to article – subscription may be required.)
- ↑ Paulus T.V.M. de Jong. Age-Related Macular Degeneration. N Engl J Med. 2006 Oct 5;355(14):1474-85 or - for subscribers only, until April 2007, full text.
