# Fractal Dimension and Retinal Pathology: A Meta-Analysis
## 3 Results
### Demographic and Clinical Characteristics of Studies from Search  
In total, 9514 subjects were considered in total for this review. We note that in reality, the number of eyes evaluated represents the true number of cases, but for compatibility reasons, we choose patients as our unit as some studies do not report the number of eyes examined. Studies focusing on diabetes mellitus mainly used random plasma glucose, Hb1 Ac test, and/or diabetes duration as diabetic factors when comparing fractal dimensions. All diabetic retinopathy studies differentiated between different stages of disease with the most (5) using the ETDRS classification [22; 23], 2 using the International Diabetic Retinopathy Severity Scale [24], and the remaining 3 not specifying a grading system. Classification of myopia varied among the myopia studies. Some studies considered patients that have high myopia, those with spherical equivalent refraction (SER) worse than \(-6\) diopters. In contrast, the World Health Organization defines high myopia as having less than or equal to 5 diopters [25]. Others included patients with varying levels of myopic refraction with a cut-off point at \(-1.00\) diopters. Of the studies which examined glaucoma, two used the International Society of Geographical and Epidemiological Ophthalmology scheme [26], while one used the Glaucoma Hemifield Test [27], pattern standard deviation, and optic nerve damage as indicators but did not say whether it was part of some standardized procedure. Studies on hypertension generally defined it as systolic blood pressure above 140 mmHg and diastolic blood pressure 80 mmHg. The clinical characteristics for each study can be seen in Table 2. Most of the studies adjusted for potential confounding factors such as age, gender, cardiovascular risk factors, and optical disorders using exclusion and/or multivariate regression. Age ranges varied between studies from schoolchildren as young at ages 11-12 to elderly adults as old as 71. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Pathology**} & \multirow{2}{*}{\begin{tabular}{c} **Number of** \\ **Subjects** \\ \end{tabular} } & \begin{tabular}{c} **Mean (SD)** \\ **Fractal** \\ **Dimension for** \\ **RNF Images** \\ \end{tabular} & \begin{tabular}{c} **Mean (SD)** \\ **Fractal** \\ **Dimension for** \\ **FFA Images** \\ \end{tabular} & \begin{tabular}{c} **Significant** \\ **Difference in** \\ **FD from** \\ **Normals?** \\ \end{tabular} \\ \hline Normal & 29 & 1.669 (0.0309) & 1.586 (0.0760) & N/A \\ \hline Glaucoma & 25 & 1.694 (0.0229) & N/A & Yes \\ \hline \begin{tabular}{c} Ocular \\ hypertension \\ \end{tabular} & 17 & 1.673 (0.1170) & N/A & No \\ \hline \begin{tabular}{c} Central Serous \\ retinopathy \\ \end{tabular} & 11 & N/A & 1.592 (0.0352) & No \\ \hline \begin{tabular}{c} Diabetic \\ retinopathy \\ \end{tabular} & 10 & N/A & 1.623 (0.0232) & Yes \\ \hline \begin{tabular}{c} Branch retinal \\ vein occlusion \\ \end{tabular} & 4 & N/A & 1.597 (0.0258) & No \\ \hline \
\begin{tabular}{c} Central retinal \\ vein occlusion \\ \end{tabular} & 3 & N/A & 1.569 (0.0470) & No \\ \hline
\begin{tabular}{c} Central retinal \\ artery occlusion \\ \end{tabular} & 2 & N/A & 1.557 (0.0254) & No \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Outcomes of fractal analysis on patients as reported by [8].