Authors’ response to comments on The effect of 2% pilocarpine on depth of field in different time intervals among presbyopic subjects

Dear Editor, We have read the comments in the “letter to editor” written regarding our article and thank the authors for their inputs and queries.[1] This study provides valuable insights into the effect of pilocarpine on the depth of field (DOFi) in presbyopic subjects.[2] As highlighted, the study was cross-sectional and incorporated no control sample. Rather, DOFi was measured before and at intervals of 15, 30, and 45 minutes after pilocarpine was administered to the same subject. Although the methodology is intuitive, I appreciate your recommendation that future research include a control group, as this could provide the results with more comparative robustness. The study was carried out in a controlled setting to reduce physiological and environmental fluctuations, and the subjects’ age and employment profiles were maintained at constant levels. Since all of the participants worked in near-vision-related fields, this ensured homogeneity in visual demands. By performing each test three times and averaging the outcomes, observation bias was mitigated, strengthening reliability. However, as you mentioned, incorporating a wavefront aberrometer might have yielded more objective DOFi measurements. Although this study was a postgraduate project without any outside funding, the device’s excessive cost and unavailability were unfortunately particular limitations. The effects of pilocarpine on DOFi were the primary focus of the investigation; accommodative amplitude was assessed separately as part of the whole project. This article encompasses a specific goal, and we intend to publish results about accommodative amplitude in an upcoming article. Regarding the suggestion for assessing accommodative responses using optical coherence tomography (OCT), it should be noted that OCT is not able to quantify these responses objectively because its usage is restricted to structural imaging rather than functional assessments. Due to time constraints and participants’ reluctance to stay longer at the data-collecting location, measures were only taken up to 45 minutes after instillation, which was another limitation of the study’s duration. This gives a basic grasp of pilocarpine’s short-term impact on DOFi, but it restricts knowledge of long-term implications. Extended follow-up times should be an aspect of future research to assess rebound effects or maintain efficacy. Mild headaches were among the side effects that were reported, although they faded aside in 30 to 60 minutes. Since the main goal of this study was to investigate how pilocarpine affected DOFi, a detailed record of these side effects was outside its purview. Crucially, this study intends to encourage more research into pharmaceutical methods rather than endorsing pilocarpine as a treatment for presbyopia. Although, it is noteworthy that studies like Grierson et al.[3] (1979), which investigated the effects of pilocarpine on glaucoma and the anterior chamber angle, highlighted adverse consequences. However, whereas this study used 2%, which is less likely to have major adverse outcomes, their study used a greater concentration (2–4%). This study provides a foundation for future research on pilocarpine’s potential in treating presbyopia, despite limitations like lack of a control group, brief observation period, and advanced equipment. Ethical approval The Institutional Ethical Committee of our institute gave its permission to the study protocol (approval number: SEH/LDH/EC/2022/04). Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.