Chances are that if you asked a retina specialist: “If you were trapped on an island full of patients with AMD and had access to only one diagnostic tool to rely upon, what would it be?” I bet most would say the OCT.
The first use of OCT in ophthalmology was described by Puliaftio, et al in 19951. Since that time, its use has exploded in the management of vitreoretinal diseases. The majority of retina specialists employ OCT to help manage patients with wet AMD. The OCT plays two crucial roles in evaluating new patients referred with a diagnosis of “AMD”. First, it can help establish the diagnosis of neovascular AMD by demonstrating intraretinal edema, subretinal fluid, or elevation of the RPE. Second, it provides a baseline to assess the effect of treatment.
In the era of anti-VEGF treatment, OCT may be the most reliable indicator of a response to treatment due to the fact that it is so sensitive in detecting the earliest changes associated with reactivation of choroidal neovascularization. Visual acuity can fluctuate in patients with AMD and patients with significant vision loss often cannot detect the early recurrence of a choroidal neovascular membrane. I must admit that if a patient feels there vision is stable and the OCT shows an increase in subretinal fluid or intraretinal edema, I would definitely recommend retreatment. Whereas if a patient felt their vision was worse (or they had a loss of vision) and the OCT showed no signs of activity, I would be more skeptical about their need for retreatment.
The best is about to get a lot better…
The new generation of OCT machines will use spectral domain technology that will allow for the capture of the entire macula and rapid review of every “slice” of the macular map. This will eliminate the possibility of an early area of leakage that is not detected on the traditional horizontal and vertical OCT scans. Furthermore, the macular mapping function will be much more precise than the current version which is prone to artifacts. Finally, many of these new machines will have other diagnostic imaging capabilities (such as SLO and fundus photography) which will allow for simultaneous imaging of the retina. This will provide the clinician with the ability to determine whether there is hemorrhage or other changes (RPE tear, etc) which could effect the treatment decision.
In summary, any vitreoretinal specialist planning on getting stranded on an island full of AMD patients, better remember to pack his or her spectral domain OCT. Good luck getting it past security!
Reference:
1 Puliafito CA, Hee MR, Lin CP, et al. Imaging of macular diseases with optical coherence tomography. Ophthalmology. 1995;102(2): 217-229.
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