With the development of refractive surgery, the size of scotopic pupil has been widely concerned by clinicians. Historically, the measurement of pupil size included the use of a pupil ruler, which is known for its drawback of being very subjective and lacking precision. While infrared pupillometry devices such as OPD-Scan III and Sirius are available for accurately and reliably measuring pupil size. Nevertheless, the aforementioned equipments are costly and cumbersome to move in terms of screening and field trial logistics settings. And 2WIN-S is a portable refractor, it can in a short period of diopter and scotopic pupil size and other data obtained at the same time. Therefore, the aim of this study was to compare the agreement between 2WIN-S and OPD-Scan III in measuring scotopic pupil size and the repeatability of 2WIN-S.

Pupil diameter is a parameter of great interest in understanding brain systems and modern refractive surgery. Pupillometry, the measurement of variations in pupil dilation, has offered encouraging evidence for the involvement of disturbed reactivity in depression risk, according to studies. According to research, the pupil dilates in reaction to stimuli requiring a larger cognitive load or a greater emotional intensity. Importantly, studies have related pupil size variations to brain activity in regions associated with emotion regulation, including the dorsolateral prefrontal cortex (DPFC) and the agenesis of the corpus callosum (ACC) . Thus, pupillometry is proposed as a viable peripheral gauge for a variety of brain systems involved in the processing of emotional information.

Some of the postoperative complaints of patients having refractive corneal or lens surgery are related to visual quality and are associated with large pupils since optical aberrations become more dominant when the pupil dilates . If the pupil size exceeds the optical zone size, a marked increase in higher-order aberrations could be observed. Patients might complain about poor contrast sensitivity, increased glare disability, or halos. Precise measurement of scotopic pupil diameter has therefore become an essential step in the preoperative evaluation of patients suitable for refractive surgery and is an important inclusion or exclusion criterion.

This study aimed to assess the agreement and reproducibility of scotopic pupil size measurements using 2WIN-S compared with OPD-Scan III in Chinese adults.

Inclusion Criteria:

• >18 years old
• signed informed consent
• willing to participate in the study

Exclusion Criteria:

Exclusion criteria were ocular pathology known to interfere with pupillometer outcome and pupil abnormalities (eg: glaucoma, iritis, cataract, corneal scarring, any history of ocular surgery, and history of trauma.)

adults attending ophthalmology clinic