Geographic atrophy: Etiopathogenesis and current therapies

Geographic atrophy: Mechanism of disease, pathophysiology, and role of the complement system

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD), characterized by atrophic lesions that first start in the outer retina and progressively expand to cover the macula and the fovea, the center of the macula, leading to irreversible loss of vision over time. GA is distinct from wet or neovascular AMD (nAMD), the other form of advanced AMD. Neovascular AMD is characterized by new invading leaky blood vessels in the macula that can lead to acute vision loss. GA and nAMD may coexist in the same eye. The underlying pathophysiology of GA is complex and thought to involve chronic inflammation due to overactivation of the complement system that leads to the loss of photoreceptors, retinal pigment epithelium (RPE), and the underlying choriocapillaris. The disappearance of these structures appears as sharply demarcated atrophic lesions that are typical of GA. Researchers have reported about 1 million reported cases of GA in the United States, and about 160,000 cases occur per year. The most important risk factors for GA are increasing age and family history. Diagnosis of GA is usually made by using multimodal imaging techniques. Lesions associated with GA are highly heterogeneous, and the growth rate may differ from patient to patient. Despite the progressive nature of GA, the fovea may be spared until much later in the disease, thereby retaining central vision in patients. With time, atrophic lesions may progressively grow to involve the fovea, thereby severely impairing central vision. Vision loss can happen rapidly once the lesions reach the fovea. However, even without the involvement of the fovea, ongoing vision impairment impacting daily life may be present. Median time from GA not involving the center of the fovea (without subfoveal involvement) to GA with lesion boundary affecting the foveal center (subfoveal involvement) ranges from 1.4 to 2.5 years. GA can greatly impact patients' functioning and quality of life and limit their independence by interfering with activities of daily living, including difficulties with reading, driving, watching television, recognizing faces, and being unable to do household chores. No treatments have been available until intravitreal pegcetacoplan was recently approved by the US Food and Drug Administration for GA secondary to AMD. DISCLOSURES: Dr Bakri serves as a consultant to Apellis Pharmaceuticals, as well as AbbVie, Adverum, Eyepoint, iLumen, Iveric Bio, Genentech, Novartis, Outlook Therapeutics, Pixium, Regeneron, Roche, and Regenxbio. Drs Sharp, Luo, and Sarda are employees of Apellis Pharmaceuticals. Dr Bektas and Ms Khan are employees of RTI Health Solutions. Apellis developed and led the concept design of this publication, review and interpretation, approval, and decision to publish. This research was developed under a research contract between RTI Health Solutions and Apellis Pharmaceuticals and was funded by Apellis Pharmaceuticals. This supplement is to describe the disease of geographic atrophy and was funded by Apellis. Apellis Pharmaceuticals has developed Syfovre (pegcetacoplan), the first and only treatment for geographic atrophy.

Long-term progression of geographic atrophy in age-related macular degeneration does the phakic status matter?

PURPOSE

To assess the long-term risk of geographic atrophy (GA) progression after cataract surgery.

METHODS

Subjects with GA secondary to AMD followed for at least 1 year with fundus autofluorescence imaging and with at least two visits at our centre were included. Patients with wet AMD, disciform scar, past history of intravitreal injections or laser treatment, other maculopathies and with poor quality images were excluded. GA area at baseline and at follow-up visit was measured. Three study groups were defined according to their phakic status: (A) pseudophakia, (B) phakic and (C) phacoemulsification surgery performed during the study. Differences of GA area progression were compared between these study groups. In addition, comparison between GA progression rate in group (C) before and after the surgery was performed. The enlargement rate (ER) was calculated for lesion size after transforming the measurements to the square-root scale.

RESULTS

A total of 92 eyes of 92 patients were enrolled. Median follow-up time was 4 [1-10] years. Regarding the eye's phakic status, 29 (31.5%) were pseudophakic and 63 (68.5%) were phakic; of these, 22 underwent phacoemulsification during the study. Overall, the median baseline and follow-up area of GA were 1.42 [0.04-32.10] mm² and 6.48 [0.25-47.40] mm², respectively. The ER was similar between phakic and pseudophakic eyes (0.18 [0.01-1.03] vs 0.15 [0.01-0.65] mm/year, p = 0.62). In patients that underwent cataract surgery during the study, the GA ER remained stable (0.13 [0.01-0.92] vs 0.14 [0.01-0.63] mm/year, p = 0.43).

CONCLUSION

These results suggest that cataract surgery does not increase the risk of pre-existing GA progression. Therefore, cataract surgery seems safe and a potential therapeutic weapon to improve visual acuity and consequently quality of life in GA patients.

Impact of ocular and systemic risk factors on progression of geographic atrophy in age-related macular degeneration

BACKGROUND

Geographic atrophy (GA) corresponds to an end-stage form of age-related macular degeneration and the leading cause of irreversible vision loss. The aim of this study was to investigate the role of fundus autofluorescence (FAF) patterns surrounding GA, baseline GA size, the presence of reticular pseudodrusen (RPD), the condition of the fellow eye and the presence of systemic vascular diseases (diabetes, atherosclerosis, systemic hypertension) on the progression of GA due to age-related macular degeneration.

METHODS

Seventy-five eyes of 52 patients with GA were included into this retrospective study. Digital FAF images were achieved using scanning laser ophthalmoscopy. Areas of GA were measured with the Region Finder software program on an Heidelberg Retinal Angiograph 2. FAF patterns around GA were classified and the presence of RPD and systemic diseases were noted. The median follow-up of the patients was 2.6 years (interquartile range, 1-9.2).

RESULTS

The median progression rate of the banded pattern (median 0.97 mm²/year) was significantly higher than the other patterns (median 0.85 mm²/year) (p = 0.03). Eyes with RPD had a significantly higher progression rate (median 1.21 mm²/year) than those without RPD (median 0.79 mm²/year) (p = 0.007). The presence of systemic diseases was not related with lesion progression rates.

CONCLUSIONS

The results demonstrate that the banded pattern and the presence of RPD accelerate the progression of GA and function as predictive factors.

Racial differences and determinants of macular thickness profiles in multiethnic Asian population: the Singapore Epidemiology of Eye Diseases Study

Aim

To evaluate racial differences, and ocular and systemic determinants of macular thickness (MT), measured by spectral-domain optical coherence tomography (SD-OCT) in a normal multiethnic Asian population.

Method

MT was measured from a 6×6 mm2 central macular area using the Cirrus high-definition OCT (HD-OCT) (Carl Zeiss Meditec, Dublin, CA). The associations between ocular and systemic factors with MT were evaluated using linear regression analyses with generalised estimating equation models to account for intereye correlation.

Results

7447 healthy eyes (2577 Chinese, 2072 Malays and 2798 Indians) of 4510 subjects were included. Multivariable analysis showed that older age (per decade, β=−4.39), female gender (β=−5.74), diabetes (β=−1.10), chronic kidney disease (CKD) (β=−3.21), longer axial length (per mm, β=−2.34), flatter corneal curvature (per mm, β=−1.79) and presence of cataract (β=−0.94) were associated with thinner overall average MT (OMT) (all p≤0.026); higher total cholesterol (β=0.44; p=0.010) was associated with thicker OMT. All these factors were also associated with thinner central subfield MT (CSMT) (all p≤0.001), except for cataract, total cholesterol and CKD. Meanwhile, longer axial length (β=2.51; p<0.001) was associated with thicker CSMT. OMT (mean±SD) was thickest in Chinese (279.9±12.5 µm), followed by Malays (276.5±13.7 µm) and Indians (272.4±13.1 µm), with p≤0.003 for all interethnic comparisons. Similar trend was observed for CSMT.

Conclusion

There are interethnic differences in MT profile among Asians, particularly between Chinese and Indians. Ocular and systemic factors affect MT measurements as well. This Asian-specific information may be incorporated into existing clinical interpretation of macular OCT scans to aid in improving the diagnostic and monitoring accuracy of macular diseases among Asians.