Diabetic retinopathy (DR), one of the leading causes of visual impairment and blindness worldwide, is one of the major microvascular complications in diabetes mellitus (DM). Globally, DR prevalence among DM patients is 25%, and 6% have vision-threatening problems among them. With the higher incidence of DM globally, more DR cases are expected to be seen in the future. In order to comprehend the pathophysiological mechanism of DR in humans and discover potential novel substances for the treatment of DR, investigations are typically conducted using various experimental models. Among the experimental models, in vivo models have contributed significantly to understanding DR pathogenesis. There are several types of in vivo models for DR research, which include chemical-induced, surgical-induced, diet-induced, and genetic models. Similarly, for the in vitro models, there are several cell types that are utilised in DR research, such as retinal endothelial cells, Müller cells, and glial cells. With the advancement of DR research, it is essential to have a comprehensive update on the various experimental models utilised to mimic DR environment. This review provides the update on the in vitro, in vivo, and ex vivo models used in DR research, focusing on their features, advantages, and limitations.
Sudden blindness in pregnancy is a devastating experience for the patient, her family and the treating obstetrician. Four cases of cortical blindness with pregnancy induced hypertension are presented, seen at the General Hospital Kota Bharu, Kelantan, in 1990. The incidence at the GHKB was 1: 1559 (4 cases out of 6,237 deliveries) which is higher as compared to neighbouring Singapore. The pathophysiology of this condition is still not well understood, though it is hoped that newer sophisticated imaging techniques like magnetic resonance imaging (MRI), CT scan, and blood flow waveform analysis by Doppler ultrasound will throw some light on the subject. Two of our cases presented with antepartum and two with postpartum cortical blindness. Therefore, termination of pregnancy alone may not provide the solution to this therapeutic dilemma.
A female Malay patient with acute lymphoblastic leukemia in remission for one year developed bilateral visual loss. The ophthalmoscopic appearance showed infiltration of optic nerves and retinae by leukemic cells. At that time, her blood, bone marrow and cerebral spinal fluid remained normal. She had received prophylactic cranial irradiation and intrathecal methotrexate as part of the treatment programme. It was likely therefore she had a leukemic relapse from a pharmacologic sanctuary in the eyes. She responded to local irradiation but did not regain her sight. Three months later, she had a bone marrow relapse.