## 1 Introduction  
Glaucoma, a type of optic nerve damage that can cause vision impairment and lead to blindness, is the second most common cause of blindness worldwide. According to the World Health Organization (WHO), more than 76 million people suffered from glaucoma in 2020, which is expected to increase to 111.8 million by 2040 [1]. Because glaucoma has no noticeable symptoms in the early stage, it is nicknamed the silent thief of sight [2], and 90% of glaucoma is not detected early. If glaucoma patients are not diagnosed and treated in time, they may be permanently blind as the optic nerve is damaged. It is crucial to develop glaucoma detection systems for early diagnosis. Glaucoma is mainly related to high intraocular pressure, which can cause damage to the optic nerve. As the optic nerve degenerates, glaucoma patients' vision gradually narrows, eventually leading to blindness. Therefore, it is essential to monitor intraocular pressure at any time and use instruments to diagnose glaucoma and evaluate changes in the optic nerve objectively. To accurately diagnose glaucoma, ophthalmologists will conduct a series of examinations for patients in clinical diagnosis, including:1. Intraocular pressure test: The normal intraocular pressure is 10-21 mmHg. When the intraocular pressure is higher than 22 mmHg, the risk of glaucoma is higher. 2. Visual field test: Visual field refers to the range that the eyes can see. Standard Automated Perimetry (SAP) can describe the visual field of the patient's eyes. When a defect in the central visual field or the peripheral visual field narrows, it may be a symptom of glaucoma. 3. Fundus photography: In both normal people and people with abnormal optic nerves, the vast majority have optic disc depressions, but the depression of optic discs in glaucoma patients will increase or show different changes with the disease. Experienced ophthalmologists use fundus photography to screen patients for possible glaucoma. Figure 1 shows fundus OCT images of (a) healthy and (b) unhealthy retinas [3]. The fundus image and the important parts of the eye are marked in Figure 2.
4. Optical coherence tomography (OCT) examination: using optical principles to conduct cross-sectional analysis of the cornea, iris, lens, retina, optic disc, optic nerve, etc., in a non-invasive manner [3; 4], as shown in Figure 3. OCT can objectively measure the thickness of the optic nerve fiber layer to assist in the early diagnosis of glaucoma. Ophthalmologists can also analyze the previous OCT images of patients to check for changes in the optic nerve to monitor and control the glaucoma condition. The quality and resolution of OCT images have given it the nickname optical biopsy in some literature [5]. However, in eye disease diagnosis, fundus photography and optical tomography (OCT) are usually not performed on the patient simultaneously. Generally, the ophthalmologist will take further OCT scanning actions when they detect any abnormalities from the prior fundus photography. The symptoms of glaucoma are not apparent in the early stage, and it is usually not easy to discover. Because OCT equipment is expensive, it is not easy for small ophthalmology clinics to afford it. Usually, only large hospitals can do in-depth OCT examinations for glaucoma. The use of computer-aided diagnosis in the screening and diagnosis of glaucoma from fundus or OCT images has become a trend with the advancement of information technology. Developing a tool for computer-aided detection of glaucoma with a high sensitivity and low false positive rate can help ophthalmologists to provide a positive clinical diagnosis. Therefore, this study hopes that the fundus photography and imaging equipment can generate OCT images while taking pictures to facilitate doctors' diagnosis and preventive treatment of glaucoma. This paper proposes a glaucoma identification method that combines generative adversarial networks and incremental learning.