In this episode of Ready, Set, Retina, Daniel Epshtein, OD, FAAO, joins Sara LeMay, OD, FAAO, to discuss a case involving geographic atrophy encroachment on the fovea and how to manage these patients.
Geographic atrophy: A review
Geographic atrophy (GA) is an advanced stage of age-related macular degeneration (AMD), resulting in a gradual, permanent loss of vision in approximately 5 million people globally.
GA features sharply defined atrophic areas in the outer retina caused by the loss of photoreceptors, retinal pigment epithelium (RPE), and the underlying choriocapillaris. These lesions usually initially develop in the perifoveal macula, sparing the foveal center, and tend to expand and merge over time to involve the fovea.1
Geographic atrophy usually involves both eyes, and perifoveal atrophy can affect visual functions such as reading, driving, and low-light vision. In contrast, foveal involvement can significantly impair central visual acuity (VA).1
Case study
An 85-year-old man with a history of exudative AMD in his right eye (OD) and geographic atrophy AMD in his left eye (OS) presented for evaluation. His last anti-vascular endothelial growth factor (VEGF) injection OD was in October 2022.
Table 1: Comparison of visual acuity and clinical findings from the posterior pole.
| Eye | Visual Acuity | Posterior Pole Findings |
|---|---|---|
| OD | 20/300 | Large disciform scar with GA |
| OS | 20/40 | Multifocal lesions well-demarcated areas of RPE loss with visible choroid, appearing hypoautofluorescent and surrounded by a hyperautofluorescent ring on FAF |
Table 1: Courtesy of Sara LeMay, OD, FAAO.
Figure 1: Fundus color photography and fundus autofluorescence (FAF) visualizing the disciform scar OD and GA OS.
Figure 1: Courtesy of Sara LeMay, OD, FAAO.
The patient is functionally monocular due to his history of wet macular degeneration OD, which was deemed inactive by an optical coherence tomography (OCT). Complement inhibitors were recommended as a treatment option for GA, but the patient chose to monitor rather than treat at this visit.
At the 4-month follow-up, FAF and OCT revealed lesions that were starting to coalesce in the superior macular region and lesions growing towards the fovea in the nasal macular area (Figure 2). Areas of choroidal hypertransmission on OCT were enlarging and extending towards the fovea.
At this point, the patient acknowledged that since he did not want to risk losing vision in his better-seeing eye, he wanted to start treatment. The patient began a complement inhibitor, which was administered every 6 to 8 weeks.
Figure 2: Progression in GA between visits at the 4-month follow-up OS (June 2023 visit on the left and October 2023 visit on the right).
Figure 2: Courtesy of Sara LeMay, OD, FAAO.
In patients undergoing clinical intervention, clinical trials typically assess changes in total GA lesion area over time (e.g., millimeters squared per year) as endpoints for evaluating GA progression and the effectiveness of therapeutic interventions, most of which aim to decrease the lesion growth rate.1
Progression of GA is variable
Some patients may ask, “When am I going to lose my vision?”
This is a complex question without a clear answer, as multiple factors can influence an individual's progression rate, including lesion characteristics such as size, focality, configuration, and location. Genetic, environmental, and demographic factors may also contribute.1
Geographic atrophy progression can be highly variable, and atrophic regions within the RPE typically begin in the perifoveal region and expand to involve the fovea. Progression rates range from 0.53 to 2.6 mm2/year, with a median rate of ~1.78 mm2/year; larger, multifocal, and extrafoveal lesions progress faster. Obtaining imaging such as color fundus photography, FAF, and OCT is valuable for monitoring progression.1
Tracking GA progression on fundus autofluorescence
FAF can be particularly valuable, as GA lesions appear as areas of decreased autofluorescence (hypoautofluorescence) due to the loss of RPE cells containing fluorophores, such as lipofuscin. It is one of the predominant modalities for assessing GA lesion size and progression. GA lesions on FAF can also exhibit abnormal hyperautofluorescence patterns surrounding the atrophic regions.1
Generally, FAF signals are decreased in regions affected by GA, though it may be difficult to determine which lesions are responsible for the decrease. Since the fovea appears darker than surrounding areas in a healthy retina—due to normal luteal pigment—assessing foveal integrity in GA cases with only FAF can be difficult.
In such cases, using additional imaging techniques, such as OCT, can be crucial for verifying lesion borders.1
Setting patient expectations around GA progression
Nevertheless, there are strategies to set realistic expectations and communicate effectively with patients. Showing fundus and OCT images can be an excellent way to enhance patient education and illustrate the proximity to the fovea and its potential impact on daily activities.
Explain to patients that perifoveal atrophy impacts visual abilities such as reading, driving, and low-light vision, while foveal involvement can significantly affect central VA.1 Emphasize the importance of sparing the fovea to preserve functional vision.
To learn more about the effect of GA on visual acuity, check out How Geographic Atrophy Impacts Functional Vision!
Which GA patients should be referred?
The median time to develop central GA after initial GA diagnosis is 2.5 years.2 For Dr. LeMay, multifocal lesions and larger atrophic lesions are usually strong predictors that the patient will develop progressive GA. A clinician can also evaluate the individual growth rate of the patient if images from previous examinations are available to review.
Dr. LeMay shared three categories of GA patients who should be referred to a retina specialist:
- Patient is functionally monocular with extrafoveal GA.
- For example, if a patient has wet macular degeneration, amblyopia, or injury in the worse-seeing eye, it’s best to refer patients to a retina specialist to ensure they are aware of available treatment options.
- Patient with juxtafoveal GA.
- These patients typically don’t have much time before GA affects the central fovea, so it’s best to discuss complement inhibitors as soon as possible to give them time to weigh the advantages and disadvantages of the treatment.
- Patient with extrafoveal GA with progression.
- Assessing each patient's progression rate is essential for effective management. Monitoring patients is feasible when imaging is utilized properly. Comparing current images with previous ones allows for an estimate of their progression speed and enables quick referral if the progression appears too rapid.
Final thoughts
Monitoring GA is vital, since progression rates vary significantly among patients and are affected by various factors. Imaging methods like OCT and fundus autofluorescence are critical for observing changes in lesion size and location.
In the era of complement inhibition therapy, it is important to carefully monitor GA patients for progression and to consider treatment to prevent irreversible vision loss.
