mechanisms and pathophysiology of RVAC, RAP, or ORCA diverge, in a practical sense, any and all of these are still treated with anti-VEGF injections the same as in more common forms of CNV secondary to AMD, with possible exception of polypoidal choroidal vasculopathy.

9.15Follow-up

Angiographic evaluation of thermal laser and photodynamic therapy will be presented – as much for historical interest as practical use. With anti-VEGF therapy OCT is commonly used to gauge treatment frequencies and follow-up intervals. More complete descriptions of methods and techniques will be discussed later in the book.

9.15.1 Thermal Laser

Generally patients treated with thermal laser are seen 2 weeks after the laser, and they have repeat fluorescein angiography at that time. Most patients with successful thermal photocoagulation of the neovascularization will have complete resolution of subretinal fluid by 2 weeks. Persistence of the neovascularization would be indicated by the continued presence of an area of hyperfluorescence during fluorescein angiography. Patients are then seen 4 weeks after the laser for a repeat examination and angiogram. Any subretinal fluid present at this time point indicates the presence of persistent neovascularization. The presence of persistent neovascularization is generally indicated by hyperfluorescence at the edge of the treated lesion. Angiography should show atrophy from the laser with hypofluorescence in the center of the lesion in the early and midphases of the angiogram. Late staining of the lesion particularly in the center without involvement of the edge does not necessarily indicate the need for additional laser. Laser photocoagulation can be applied as a “touchup” to areas of persistence.

Recurrent neovascularization is defined as the growth of new vessels 6 weeks or more after thermal laser photocoagulation. This may occur in several different patterns. There may be a focal area of hyperfluorescence at the border of a previously treated area. There may be a more subtle area of

occult CNV extending from a previously treated area. This usually appears as an area of stippled hyperfluorescence with or without pronounced thickening at the layer of the RPE. Finally there may be ophthalmoscopically visible signs of exudation such as blood or lipid. Generally recurrences occur on the foveal side of a previously treated lesion. On occasion these may be treated with additional thermal laser, oftentimes the neovascularization has extended under the fovea, and the patient requires other types of treatment.

9.15.2 Photodynamic Therapy

One week following PDT the area of the neovascularization generally looks dark [36]. This is probably from a combination of non-perfusion of the vessels with blockage effects as well. Of interest is that patients with retinal vascular contribution to the neovascularization often do not show a non-perfused picture at 1 week. After PDT the lesions start to show perfusion of the larger vascular stumps first, followed over days to weeks by smaller vessels [36]. Observation of the larger stumps may offer a method of feeder vessel treatment – thermal laser treatment of the stumps may prevent reperfusion of the larger vascular structure. Most patients will have reperfusion of the lesion by 6 weeks. By convention, the main studies of PDT in AMD waited 3 months to re-examine the patient. Leakage seen during angiography 3 months after treatment indicated the patient needed retreatment. The return of the vessels was not unexpected, since the vessels were never truly destroyed. Therefore, leakage seen at 3 month intervals is not termed a recurrence. At the 3-month follow-up time, 90% of patients in the TAP trial showed leakage from the lesion and were retreated. Generally, with each retreatment, the lesion is smaller and leaks less vigorously.

9.15.3 Anti-VEGF Therapy

Shortly following anti-VEGF therapy, the lesion will show much less fluorescein leakage (Fig. 9.12). The lesion itself does not decrease in size. It may still be possible to see larger vessels of the lesion in silhouette. At 1-month follow-up, it is quite common to see

lesions start to leak again. This leakage is readily visible during fluorescein angiography. Due to the frequent and recurrent nature of anti-VEGF therapy, and due to the lack of evidence supporting its practice, fluorescein angiography is not generally done on a monthly basis by most treating physicians. It is common to monitor the status of patients with OCT. Monthly dosing of anti-VEGF agents may be the most efficacious way to use them. Less frequent dosing based on OCT follows two main strategies. The first is to monitor patients monthly and give an injection of anti-VEGF agent when there are OCT signs of exudation. This means a patient would not show signs of exudation for more than 1 month prior to treatment. The potential negative of this strategy is that the macula is used as a thermometer for intraocular VEGF levels. Recurrent bouts of edema may prove to cause lasting damage. The second main strategy is to treat a patient at every visit, but to extend the followup for longer durations if the OCT does not show signs of exudation. This strategy is called treat and extend. Patients treated with this strategy are often treated at 6, 7, or 8 week intervals. Some patients need to be treated at more frequent intervals, however. This topic will be treated in more detail in subsequent chapters.

Summary for the Clinician

›Fundus photography, autofluorescence imaging, and optical coherence tomography form the core noninvasive methods of imaging the fundus in eyes with AMD.

›Integration of information from each of these modalities improves our understanding of the physiology of macular health and disease.

›Noninvasive imaging complements what is found by angiographic evaluations.

›Angiographic methods supply information about the anatomic structure and the physiologic alterations associated with AMD.

›For most eyes, fluorescein angiography supplies sufficient information to establish the diagnosis, and indocyanine green angiography is not needed.

›When polypoidal choroidal vasculopathy is suspected, indocyanine green angiography is very helpful.

›Indocyanine green angiography is useful to rule out the presence of choroidal vascular hyperpermeability from central serous chorioretinopathy.