Incidence and types of spontaneous cataracts in an aged non-human primate population

Abstract

Purpose : Cataracts, a prevalent human disease, significantly impact a large portion of the population. The primary treatment for cataracts currently involves surgical removal of clouded lenses and the subsequent implantation of artificial lenses. Due to inadequate understanding of its exact molecular mechanisms, the development of drug therapy remains a continuous challenge. Utilizing translatable disease models, such as non-human primate (NHP) models, can substantially benefit the investigation of molecular mechanisms and the innovation of new medications.

Methods : A total of 301 cynomolgus monkeys (aged 15 to 27 years, average 20) underwent cataract screening. Prior to the slit-lamp examine screening procedure, animals were fasted for 16 hours. They received intramuscular anesthesia (Ketamine ≤10 mg/kg), tropicamide eye drops for pupil dilation, and proparacaine hydrochloride eye drops for local anesthesia. Cataract grades were scored by following the protocol of the Lens Opacities Classification System III (LOCSIII) (Chylack L 1993), with nuclear cataracts assessed using standard images NO1-NO6 and NC1-NC6, and cortical and posterior subcapsular cataracts evaluated using standard images C1-C5 or P1~P5.

Results : 1. Four types of cataracts were observed in the population, including nuclear cataract, cortical cataract, posterior subcapsular cataract, and a combination of cortical and subcapsular cataract. The incidence of these four types of cataracts in the 301 monkeys is detailed in the Table, with most animals exhibiting cataracts in both eyes.

2. The majority of cataracts fell within grades 0-2.9, indicating they were in the early phase of cataract development. The distribution of grades for each type of cataract is summarized in the Figure.

Conclusions : This study identified four types of cataracts in their early developmental stages (grades below 2.9) in the aged monkey population. These monkey cataracts represent translatable disease models for further exploring the molecular mechanisms of cataracts and for creating innovative cataract drugs.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Table 1. Incidence of different cataracts in KBI's aged monkey population

 

Figure 1. Grades of different cataracts in KBI's aged monkey population. The majority of cataracts fell within grades 0-2.5, indicating they were in the early phase of cataract development.