## 4 Conclusions  
This research proposes a fast and robust NMFP autofocus method to enhance the quality of fundus imaging, particularly under poor imaging conditions. The method first improves the overall performance of the sharpness evaluation curve by calculating the adaptive window, then constructs a path-optimized search based on EWMA to overcome local extrema and rapidly converge to the focus position. Experiments and simulations supported insights into issues of the focus window and search strategy. In a clinical study of 80 cases, the proposed method provided the highest autofocus success rate of 90%, with the least axial scanning compared to similar IBAF methods. Furthermore, the method exhibits robustness in non-ideal imaging conditions such as pupil misalignment, eyelash occlusion, and nystagmus. These benefits are expected to improve the efficiency and accuracy of community-based fundus screenings and alleviate challenges faced by individuals with  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Strategy** & **Expert** & **Success** & **Failure** & \begin{tabular}{c} **Success** \\ **Rate** \\ \end{tabular} & \
\begin{tabular}{c} **Motor Movement** \\ **Count** \\ \end{tabular} &
\begin{tabular}{c} **Motor Steps \({}^{*}\)** \\ \end{tabular} \\ \hline \multirow{2}{*}{IHCS} & A & 56 & 24 & 70.0\% & \multirow{2}{*}{22} & \multirow{2}{*}{7120} \\  & B & 58 & 22 & 72.5\% & & \\ \hline \multirow{2}{*}{GFF} & A & 65 & 15 & 81.3\% & \multirow{2}{*}{32} & \multirow{2}{*}{12,010} \\  & B & 64 & 16 & 80.0\% & & \\ \hline \multirow{2}{*}{POSE} & A & **72** & **8** & **90.0\%** & \multirow{2}{*}{**10**} & \multirow{2}{*}{**5626**} \\  & B & **71** & **9** & **88.8\%** & & \\ \hline \hline \end{tabular} \({}^{*}\)Motor movement count and motor steps are used to measure the search efficiency [17].  
\end{table}
Table 2: Performance comparison of three search strategies with adaptive focus window.  
Figure 9: Autofocus results for some clinical cases, using adaptive focus window combined with IHCS, GFF, and POSE strategy: (**a**) Ideal imaging condition, (**b**–**d**) non-ideal imaging conditions, including pupil misalignment, nystagmus, and eyelsh occlusion.  
difficulty in vision fixation, including children and the elderly. Future research will involve more extensive clinical studies, including patients with eye diseases that make it difficult to focus normally, as well as autofocusing peripheral retinal regions, providing possibilities for achieving precise fundus image stitching and ultra-wide-angle fundus imaging.  
Conceptualization, Z.L. and X.C.; methodology, Z.L.; software, Z.L.; validation, Z.L. and S.Q.; formal analysis, Z.L.; investigation, Z.L.; resources, Z.L. and S.Q.; data curation, Z.L.; writing--original draft preparation, Z.L.; writing--review and editing, Z.L.; visualization, Z.L.; supervision, X.C., H.C. and Y.W.; project administration, X.C. and Y.W.; funding acquisition, X.C. and H.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by MEDA Co., Ltd. Tianjin, China. The funding number is \"MEDA-2021-0810\".  
The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Tianjin University (protocol code: TJUE-2023-195, date: 16 June 2023).  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
Data Availability Statement: Data are contained within the article.  
The authors declare that this study received funding from MEDA Co., Ltd. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article, or the decision to submit it for publication.