Diabetic Retinopathy Management Guidelines

Rahul Chakrabarti; C Alex Harper; Jill Elizabeth Keeffe

Disclosures

Expert Rev Ophthalmol. 2012;7(5):417-439. 

In This Article

Disease Onset & Progression & Implications for Timing of First Examination

The necessity to examine all patients with DM for retinopathy at least every 2 years is uniformly accepted by all international guidelines. The recommended timing of first examination is largely consistent between publications and is supported by the published literature (Table 3). In the context of Type 2 DM, there was unanimous concordance among the major international guidelines is that all people should be examined using a minimum of dilated fundoscopy and visual acuity measurement by an ophthalmologist, optometrist or suitably trained professional at the time of diagnosis. For patients with Type 2 DM, consensus in the guidelines recommended ophthalmic examination (comprising of fundoscopy and repeated visual acuity measurement) at the time of diagnosis. The rationale for this was supported by the observation that time of onset of Type 2 DM is often difficult to determine,[50] and that a third of Type 2 DM patients will have some evidence of retinopathy at diagnosis.[44,51]

For children with Type 1 DM, the majority of guidelines recommend first examination to commence at or soon after puberty (aged 11–12 years). The rationale for delayed screening in children was based primarily from the WESDR, which demonstrated that DR rarely developed in children with Type 1 DM younger than 10 years of age.[43] Several follow-up studies concluded that sight-threatening retinopathy (proliferative retinopathy or macular edema) was rare before puberty.[52,53] In postpubertal patients with Type 1 DM, guidelines from New Zealand, the Pacific Islands and North America recommended first retinal examination commence after 5 years from the time of diagnosis. This is supported by evidence that showed that the prevalence of DR rapidly increased after 5 years duration of DM.[52] More recent prospective studies have demonstrated that after at least 25 years with DM, almost all patients with Type 1 DM developed DR, and between 44 and 50% developed advanced retinopathy.[54,55] For patients with Type 1 DM for more than 20 years, this conferred a 15-times greater risk of proliferative DR, and five-times greater risk of diabetic macular edema (DME), compared with those with Type 2 DM for <10 years.[30] It is important to note that guidelines were based on studies conducted in Western populations where retinopathy occurred in 8–9% in patients younger than 13 years of age, and 28–34% in those older than 13 years.[56,57] Comparatively, recent observations from Tanzania showed 22% of 5–18 year olds with Type 1 DM had evidence of retinopathy at diagnosis. These suggest that emphasis on facilitating examination earlier than 5 years from time of diagnosis for people with Type 1 DM may be required in low-resourced countries.[58]

It is established that physiologic and metabolic changes associated with pregnancy can accelerate DR.[39,59] The recommended timing of examination during pregnancy was stratified into patients with existing DM and those who developed gestational DM (GDM). In the context of patients who develop glucose intolerance during pregnancy (GDM), the AAO and NHMRC stated that DR screening was not routinely required as there was minimal risk for DR in such individuals during pregnancy. Presently, only a single case report has identified vision-threatening retinopathy arising in a patient with GDM.[60] While there is insufficient evidence assessing the temporal progression of retinopathy in this group, GDM is associated with elevated risk of long-term DM.[61] Accordingly, ophthalmic review at time of diagnosis of GDM may be justified as per the Malaysian guidelines.

For patients with DM diagnosed before pregnancy, the consensus among guidelines recommended a comprehensive eye examination for all pregnant women with DM during the first trimester of pregnancy (Table 4). This was supported by findings from the DCCT that showed greatest risk of DR progression in the second trimester of pregnancy in patients with Type 1 DM.[62] Most guidelines recommended that women with DM have an ophthalmic examination prior to becoming pregnant, and counseled on the risk of development and progression of DR. Several studies have shown that optimization of glycemic control and BP prior to conception can attenuate the risk of progression of DR.[62–64] For patients with DR detected during pregnancy, there was variation in recommended follow-up schedule between guidelines. This was partly accounted for by a deficiency of recent studies. Evidence suggests that progression of retinopathy is uncommon if absent or mild at the beginning;[62] however, vision-threatening disease can occur.[65] The DCCT also demonstrated that the short-term increased risk in the level of retinopathy in pregnancy could persist up to 12 months postpartum.[62,66,67] Accordingly, close observation of patients with DR during and after pregnancy is warranted.

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