Synergistic Effect of Nilavembu Choornam-Gold Nanoparticles on Antibiotic-Resistant Bacterial Susceptibility and Contact Lens Contamination-Associated Infectious Pathogenicity.

Antibiotic-resistant bacterial colonies mitigate rapid biofilm formation and have complex cell wall fabrications, making it challenging to penetrate drugs across their biofilm barriers. The objective of this study was to investigate the antibacterial susceptibility of antibiotic-resistant bacteria and contact lens barrenness. Nilavembu Choornam-Gold Nanoparticles (NC-GNPs) were synthesized using NC polyherbal extract and characterized by UV-visible spectrophotometer, SEM-EDX, XRD, Zeta sizer, FTIR, and TEM analysis. Contact lenses with overnight cultures of antibiotic-resistant bacteria K. pneumoniae and S. aureus showed significant differences in growth, biofilm formation, and infection pathogenicity. The NC-GNPs were observed in terms of size (average size is 57.6 nm) and surface chemistry. A zone of inhibition was calculated for K. pneumoniae 18.8 ± 1.06, S. aureus 23.6 ± 1.15, P. aeruginosa 24.16 ± 0.87, and E. faecalis 24.5 ± 1.54 mm at 24 h of NC-GNPs alone treatment. In electron microscopy studies, NC-GNP-treated groups showed nuclear shrinkage, nuclear disintegration, degeneration of cell walls, and inhibited chromosomal division. In contrast, normal bacterial colonies had a higher number of cell divisions and routinely migrated toward cell multiplications. NC-GNPs exhibited antibacterial efficacy against antibiotic-resistant bacteria when compared to NC extract alone. We suggest that NC-GNPs are highly valuable to the population of hospitalized patients and other people to reduce the primary complications of contact lens contamination-oriented microbial infection and the therapeutic efficiency of antibiotic-resistant bacterial pathogenicity.

Effect of Ultraviolet-A and Riboflavin treatment on the architecture of the center and periphery of normal rat cornea: 7 days post treatment.

Corneal collagen cross-linking (CXL) is a treatment that is widely applied to halt the progression of ectatic diseases such as keratoconus by creating biomechanical strength in the cornea. Most of the studies assessed the effect of the CXL on the cornea without any differentiation of its effect between periphery and the center of the untreated control cornea especially after the 7 days of CXL application. We investigate the ultrastructural changes in the architecture of the center and periphery of rat corneas, 7 days after standard CXL application. Five Wistar rats (10 corneas) were used in the present study. The left eye corneas (5 mm area) were de-epithelialized and irradiated with standard CXL application using riboflavin and Ultraviolet-A (UVA) (3 mW/cm2 for 30 min). The right eye corneas were used as a control. The sclera-cornea button was removed and processed for electron microscopy. Digital images were captured with a bottom mounted Quemesa camera and analyzed using the iTEM software. The ultrastructure of epithelium, hemi-desmosomes, Bowman's layer and stroma were organized in both untreated control and CXL rat cornea in both untreated control and CXL rat cornea. Within the same CXL cornea, both the collagen fibril (CF) diameter and interfibrillar spacing at the center were significantly smaller compared to the peripheral diameter and spacing of the cornea. When comparing the untreated control and CXL cornea, the central interfibrillar spacing of the CXL cornea was significantly smaller than the central spacing the untreated control cornea. In the CXL cornea the peripheral spacing was significantly higher compared to the peripheral interfibrillar spacing of the untreated control cornea. Within the CXL cornea, the proteoglycans (PGs) area and density of the periphery was significantly higher compared to the area and density of the center of the cornea. It suggests that CXL was more effective at the periphery of the cornea. This could be due to the higher amount of leucine rich PG lumican and higher diffusion of oxygen and riboflavin at the periphery cornea.

The Effect of Simulated Central Field Loss on Street-crossing Decision-Making in Young Adult Pedestrians.

SIGNIFICANCE: This study explored the street-crossing decision-making performance of young normally sighted subjects with simulated central field loss (CFL). The results suggest that using eccentric viewing enables a person to make safe and reliable street-crossing decisions. PURPOSE: This study tested the hypothesis that, as the diameter of an experimentally induced central scotoma increases, the accuracy and reliability of street-crossing decisions worsen. METHODS: Street-crossing decisions were measured in 20 young subjects aged between 23 and 31 years while monocularly viewing a nonsignalized, one-way street for different vehicular arrival times. Using a 5-point rating scale, subjects judged whether they could cross the street before vehicular arrival with habitual vision and simulated CFL with eccentric viewing. The CFL was induced using soft contact lenses with different central opaque diameters. Using receiver operating characteristic curve analysis, we obtained subjects' accuracy (amount of time in seconds where subjects either overestimated or underestimated vehicular arrival time relative to their actual crossing time) and reliability (how quickly subjects transitioned from judging insufficient to sufficient time to cross relative to their actual crossing time). RESULTS: The centrally opaque contact lenses induced central scotomata with a mean (standard deviation) diameter of 17.12° (5.83°). No significant difference in street-crossing accuracy (P = .35) or reliability (P = .09) was found between the normal, habitual vision and simulated CFL conditions. No statistically significant correlations were found between scotoma diameter and the accuracy and reliability of subjects' street-crossing decisions (P = .83 and P = .95, respectively). CONCLUSIONS: The findings of this study suggest that adopting eccentric viewing enables a person to successfully mitigate the negative effects of an absolute central scotoma on the accuracy and reliability of their street-crossing decisions.

Simulation of a central scotoma using contact lenses with an opaque centre.

PURPOSE: This study evaluated the feasibility of using soft contact lenses (CLs) with an opaque centre to induce absolute central scotomas that move with the eye. We examined the geometrical optics prediction that scotoma size will vary with the size of the CL's opaque centre and with ocular pupil size. We also tested the hypothesis that high environmental light levels will ensure that the ocular pupil will remain small enough, even with opaque centre CLs, to generate absolute scotomas representative of those experienced by patients with age-related macular disease. METHODS: Using an Octopus 900 Perimeter ( www.Haag-Streit.com), kinetic visual fields (VFs) were measured in five normally-sighted subjects using a V4e Goldmann target with CLs that had central opaque areas with diameters of 2.8, 3.0, and 3.2 mm. To control pupil size, VFs were measured with background perimeter bowl luminances of 10, 585, and 1155 cd m-2 . Subjects attempted to (i) fixate the bowl centre; and (ii) place the scotoma edge at the bowl fixation target (eccentric viewing). RESULTS: As predicted, there was a direct relationship between scotoma size and both luminance level and diameter of the opacity. Mean scotoma diameters were 0°, 17.6° and 22°, for the low, medium and high bowl luminances, respectively. Scotoma size was determined primarily by the difference between the diameters of CL opacity and the entrance pupil of the eye and the axial separation between them, and between-subject differences in pupil diameters contributed most to the between-subject variability in scotoma diameter at each light level (SD: 6.01°). Scotoma displacement during eccentric fixation confirmed the gaze-contingent characteristics of this experimental model. CONCLUSION: It is possible to induce a gaze-contingent absolute scotoma and hence mimic central vision loss using centrally-opaque CLs provided that the CL opacity is larger than the entrance pupil of the eye. This simulation tool will, therefore, be ineffective at low environmental light levels (as shown previously) if the entrance pupil of the eye is larger than the CL opacity.

Prevalence, Characteristics, and Management of Pediatric Ocular Trauma in Riyadh, Saudi Arabia: A Retrospective Analysis.

PURPOSE: Ocular trauma is a major cause of visual impairment; however, little is known about its burden in Saudi Arabia. Therefore, this study aimed to determine the epidemiological characteristics of ocular trauma in pediatric patients in Riyadh, Saudi Arabia. PATIENTS AND METHODS: Medical records of pediatric patients diagnosed with eye injuries between January 2016 and December 2020 were retrospectively reviewed. Demographic and injury characteristics were collected, and ocular trauma injuries were classified according to the Birmingham Eye Trauma Terminology. RESULTS: A total of 855 injured patients were included in the study, of whom 525 (61.4%) were boys. Patient age ranged from one month to 18 years. Most ocular injuries occurred in children aged 5-9 years. The injuries were more prevalent in boys than in girls. Closed globe injuries accounted for 70% of cases, open globe injuries for 21%, and other injuries for 9%. Most ocular injuries occurred at home (n = 87, 42%), followed by school (n = 61, 30%). CONCLUSIONS: These results may inform the implementation and targeting of interventions to reduce or prevent eye injuries in children. Further, they highlight the importance of well-planned prevention programs to prevent eye injuries from occurring in children's daily lives.

Age-related changes in reading performance in normally sighted Arabic-speaking adults.

CLINICAL RELEVANCE: Reading performance is important for evaluating near vision and predicting and prescribing near-vision correction. There is a significant gap in the literature on Arabic reading performance and its associated effects. BACKGROUND: Normative data from control participants serve as the baseline for future studies involving groups with specific characteristics. This study aimed to assess baseline measures of Arabic reading performance. METHODS: In total, 428 normally sighted adults aged 19-83 years read the Balsam Alabdulkader - Leat chart to measure their reading performance. The participants were divided into five age groups. The outcome measures were the maximum reading speed in standard-length words per minute, critical print size, reading acuity, and reading accessibility index. RESULTS: The average reading performance measures were as follows: 171 ± 27 standard-length words per minute for maximum reading speed, 0.01 logarithm of the minimum angle of resolution for critical print size, -0.17 logarithm of the minimum angle of resolution for reading acuity, and 1.02 for the accessibility index. There were significant differences among the age groups, indicating a dependency on age and showing a plateau for the young adult group and a decline with age. The accessibility index had an almost perfect correlation with maximum reading speed and a weak but significant relationship with reading acuity and critical print size. CONCLUSION: Arabic exhibits an age-dependent trend in reading speed. However, owing to differences in orthography, visual demands, and reading strategies, the magnitude of the decrease and increase differs, potentially accounting for the variations between languages, especially when compared to English. This study serves as a foundation for future studies on Arabic reading performance. Future studies should examine the reading performance in patients with low vision, study the effects of common diseases on reading ability, evaluate the effectiveness of reading devices, and assess improvements in vision rehabilitation.

Evaluating the level of visual acuity to minimise false-positives in different colour vision tests.

CLINICAL RELEVANCE: Accurate colour vision assessment is important in clinical settings to minimise false-positive errors and enhance the reliability of diagnoses outcomes. BACKGROUND: Colour vision testing is valuable in assessing the visual system, particularly given the high proportion of individuals with poor vision. This study aimed to determine the minimum visual acuity level required to perform a colour-vision test without errors. METHODS: After fogging the right eyes of 52 healthy participants using plus lenses to 1.60 logMAR, vision was evaluated using Ishihara, Hardy - Rand - Rittler Standard Isochromatic, Waggoner Pseudo-isochromatic, City University, Waggoner Computerised, and Farnsworth D-15 tests. Participants then completed these tests at lower fogging degrees (in 0.1-logMAR intervals). The acuity at which 5% of the tested population was considered abnormal was determined. RESULTS: Significant differences were found in the average visual acuity required to perform colour vision tests without errors (p < 0.05). The Waggoner Computerized test required the highest average visual acuity among the tests utilised. The Farnsworth D-15 test yielded the highest logMAR values. No significant differences were observed between the Waggoner Pseudo-isochromatic test and Hardy - Rand - Rittler Standard Isochromatic, Ishihara, and Farnsworth D-15 tests (p > 0.05). Additionally, no significant differences were found between the Ishihara and Hardy - Rand - Rittler tests (p > 0.1) or between the Waggoner Computerized and City University tests (p = 0.11). Colour vision testing maintained an accuracy ≤ 1.0 logMAR with the Ishihara and Hardy - Rand - Rittler tests, 1.1 logMAR with the Waggoner Pseudo-isochromatic and Farnsworth D-15 tests, and 0.9 logMAR with the Waggoner Computerized and City University tests. CONCLUSIONS: Insights are provided into the visual acuity thresholds required for accurate colour vision testing, which can serve as a basis for future research and provide a reference for clinical practice in this field.

Evaluation of tear meniscus height and lipid layer patterns in the tear film in domestic cats: An observational study.

Background: Healthy vision in humans and animals requires a stable tear film. The environmental factor could affect the status of the tear film. Therefore, assessing the tear film in animals is essential to avoid visual system disturbance. Aim: The current research used a noninvasive device to evaluate the tear meniscus height (TMH) and lipid layer pattern (LLP) in domestic cats. In addition, the scores were compared with those of humans with healthy eyes. Methods: Fifty-four domestic cats (28 males and 26 females; mean ± SD = 13.9 ± 18.2 months) were randomly selected and included in the study. The cats were healthy, without any ocular disorders or diseases. Fifty-four healthy eye subjects (27 males and 27 females; mean ± SD = 25.6 ± 5.1 years) were randomly recruited and took part in the study for comparison. EASYTEAR View+ was used, for the first time, to assess the tear film parameters on the right eye of each subject. The examiner allowed a 5-minute gap between the tests. Each test was performed by the same examiner three times, followed by calculating the mean scores. Results: Significant differences (Mann-Whitney U test) were found in the median scores of LLP (p = 0.009) between cats and subjects with healthy eyes. The median TMH score was higher in cats (0.18 mm) than in humans (0.14). However, no significant difference (Mann-Whitney U Test, p = 0.210) exists in the TMH scores between cats and humans. The LLP analysis indicated that a dense white-blue lipid layer (grade 4 or D; lipid layer thickness, LLT, = approximately 80 nm) was predominant in both cats (N = 24, 44.4%) and humans (N = 29, 53.7%). In comparison, variable colors lipid layer (grade 5 or E; LLT = 90-140 nm) was a minority in cats (N = 5, 9.3%) and common in humans (N = 16, 29.6%). The statistical analysis indicated medium correlations between cats' TMH and LLP scores (r = 0.431, p < 0.01) and between age and TMH scores in humans (r = 0.440, p < 0.01). In addition, it indicated a weak correlation (r = 0.291, p < 0.05) between the LLP scores in cats and humans. Conclusion: Assessing animals' tear film is essential to avoid any ocular disorders. EASYTEAR View+ is efficiently used to evaluate domestic cats' TMH and LLP. Cats have thicker lipid layers and longer TMH comparable to those reported for humans with healthy eyes.

Assessment of lipid layer patterns in domestic dogs and rabbits: an observational study.

Background: Maintaining a stable tear film is crucial for having healthy human and animal vision. Animals are expected to have thicker lipid layers than humans due to living in high-temperature and humid environments. Aim: The study aimed to evaluate the lipid layer patterns (LLPs) in Arabian dogs and rabbits using a non-invasive, practical, and easy-to-use device and compare them to humans with healthy eyes. Methods: The study included 75 domestic Arabian dogs (42 males and 33 females; mean ± SD = 6.1 ± 12.7 months) and 75 rabbits (37 males and 38 females; mean ± SD = 3.1 ± 3.4 months). In addition, 75 individuals with healthy eyes (39 males and 36 females; mean ± SD = 25.7 ± 5.0 years) were included for comparison. EASYTEAR View+ assessed the LLP in each animal's and individual's right eye. Results: The median LLP grades significantly differed between dogs and humans (Mann-Whitney U test, p < 0.001). Similarly, the LLP grades differed significantly between rabbits and humans (Mann-Whitney U test, p < 0.001). No significant difference (Mann-Whitney U test) in the LLP grades between dogs and rabbits was found. The analysis indicated that most dogs had either an A (34.7%) or a B grade (37.3%). Similarly, rabbits had predominantly A or 1 (46.7%) and B (30.7%) grades. On the other hand, humans had predominantly D (53.3%) and E (30.7%) grades. Conclusion: The EASYTEAR View+ has been employed to assess LLP in dogs and rabbits, and the measurements were compared to those of humans with normal ocular health. Dogs and rabbits have thinner lipid layers than healthy humans.

Can chromatic text/background improve Arabic reading performance?

PURPOSE: Colors have been shown to improve reading performance; however, the effect of colors on Arabic orthography has not been studied. This study aimed to design and create a chromatic acuity chart to evaluate the effect of chromatic contrast on Arabic reading performance. METHODS: Color selection for the newly developed chromatic acuity chart was based on the contrast between the L, M, and S cones. The colors were chosen to have a luminance of approximately 13.6 cd/m2 with red text on a green background. A Pantone color guide set was used to choose the colors. Fifteen healthy individuals aged 19-27 years were recruited. Reading performance was measured using the newly developed red-green (R-G) chart and compared with the original achromatic Balsam Alabdulkader-Leat (BAL) chart with a luminance of 95 cd/m2. The outcomes were maximum reading speed in standard-length words per minute (SLWPM), reading acuity (RA), and critical print size (CPS). RESULTS: The mean R-G SLWPM of 201 wpm was similar to that of the BAL chart (P < 0.05). The mean RA for the R-G chart was - 0.05 logMAR and - 0.20 logMAR for the BAL chart (P < 0.05). The CPS for the R-G chart was 0.36 logMAR, significantly higher than the original chart of 0.17 logMAR (P < 0.05). CONCLUSION: This study showed that the reading performance for a text that varies only in chromatic contrast along the R-G axis reduces the reading performance for CPS and RA. Individuals showed an approximate decline of two lines on an Arabic continuous text chart compared with a high-contrast achromatic chart. This information can be used to further develop a set of near-reading charts that can efficiently determine whether there is a differential loss in chromatic and achromatic sensitivity in patients with various vision disorders.

Perspectives and clinical practices of optometrists in Saudi Arabia concerning myopia in children.

AIM: To investigate the practice patterns of optometrists in Saudi Arabia regarding myopia management. METHODS: An internet-based survey was distributed to all practicing optometrists in Saudi Arabia (n=1886). The survey contained questions related to 1) demographics, 2) knowledge about myopia and its associated complications, 3) current clinical care, 4) type and frequency of myopia treatment prescribed, and 5) potential barriers limiting treatment adoption. RESULTS: The completed surveys were collected from 171 optometrists (9.06% response rate, 60% male). Knowledge regarding myopia-associated complications was prevalent but somewhat inaccurate among the respondents. Cycloplegic refraction at initial visit was used by 59% of the respondents. The cover test was the most reported binocular vision test (83%), and 38% of optometrists did not perform any ocular biometrics. Two-thirds prescribed single-vision spectacles for children with myopia. Increased time spent outdoors was selected by 80% of the practitioners who prescribed myopia control treatment as the primary approach. Insufficient support and lack of clinical experience in providing myopia treatment were reported as the most important factors limiting the adoption of myopia management strategies. CONCLUSION: The current optometric practices in Saudi Arabia require further investigation. Optometrists appear to be somewhat aware of myopia and the associated risks. However, most evidence-based myopia treatments are not being locally adopted, primarily because of lack of support, lack of experience, and limited availability.

Effect of monovalent electrolyte solutions on the human tear ferning pattern.

PURPOSE: To investigate the effect of the addition of a low concentration of sodium chloride (NaCl) and potassium chloride (KCl) solutions on the tear ferning (TF) patterns of tears collected from humans. METHODS: A tear sample (20 µL) was collected from the right eye of 23 males and 7 females (25.4 ± 6.6 years). The tears were collected in one sitting for healthy subjects (N = 13). For dry eye participants (N = 17), the tear samples were collected in two separate settings with five minutes gap in between. A sample (1 µL) from each tear was dried on a glass slide, and the obtained ferns were observed using a microscope and graded using the five-point TF grading scale. Mixtures of tear samples (0.5 µL) and different volumes (0.5-2.5 µL) of each electrolyte (10-30 mg in 100 mL of water) solution were prepared, and their TF patterns were recorded and compared with those of the corresponding pure tears. RESULTS: Significant improvements (Wilcoxon test, P < 0.001) have been seen in the TF grades of the tear samples after the addition of NaCl and KCl solutions. A significant difference (Wilcoxon test, P = 0.016) was found between the TF grades when NaCl and KCl solutions were added to the tear samples. The TF grades of pure tears collected from dry-eye subjects ranged from 2.1 to 3.5, based on the five points grading scale, and decreased to be in the range of 0.4 to 1.6 after the addition of electrolyte solutions. While the TF grades of pure tears collected from normal-eye ranged from 1.2 to 1.9 and improved after the addition of electrolyte solution to be in the range of 0.4 to 1.5. CONCLUSIONS: The TF test was used in vitro to assess the impact of the addition of a low concentration of sodium and potassium chloride solutions on tears collected from humans. The TF grades of human tears significantly improved after the addition of either sodium or potassium chloride solution. The mechanism for the improvement in TF grades due to the addition of electrolyte solutions must be investigated.

Correlation between osmolarity measurements using the TearLab™ and I-Pen® systems in subjects with a high body mass index.

BACKGROUND: Osmolarity is used to detect symptoms of dry eye disease (DED) and can be measured using TearLab™ and I-Pen® systems. OBJECTIVES: To investigate the correlation between osmolarity measurements using the TearLab™ and I-Pen® systems in subjects with a high body mass index (BMI). MATERIAL AND METHODS: Thirty male subjects with a high BMI (27-48 kg/m2; 23.3 ±2.1 years old) participated in this study. The control group consisting of 30 healthy males (24.9 kg/m2; 22.9 ±2.1 years old) was also enrolled. Osmolarity measurements were recorded from the right eye using the TearLab™ and I-Pen® systems, and interviews were conducted to determine ocular surface disease index (OSDI) scores. RESULTS: The OSDI (p = 0.042), TearLab™ (p < 0.001) and I-Pen® (p < 0.001) scores were significantly higher in the study group than in the control group. In the study group, OSDI scores ranged from 2 to 16 (median 8.0, interquartile range (IQR) 6.8), while it was from 0 to 10 (median 6.3, IQR 4.1) in the control group. The TearLab™ osmolarity scores were in the range of 278-309 mOsm/L in the study group, whereas the I-Pen® osmolarity measurements were in the range of 294-336 mOsm/L in the study group, compared with 263-304 mOsm/L and 278-317 mOsm/L in the control group, respectively. In the study group, there was a strong correlation between the TearLab™ and I-Pen® osmolarity scores (r = 0.934; p = 0.001). In addition, strong correlations were found between the BMI and both TearLab™ (r = 0.736; p = 0.001) and I-Pen® (r = 0.707; p = 0.001) scores, as well as between the OSDI scores and both TearLab™ (r = 0.731; p = 0.001) and I-Pen® measurements (r = 0.666; p = 0.001). CONCLUSION: Osmolarity measurements using the I-Pen® system were significantly higher than those recorded using the TearLab™ system in subjects with a high BMI. The I-Pen® measurements showed large variations in osmolarity scores and were highly unreliable in correctly identifying normal eyes compared to the TearLab™ system. Also, a strong correlation was found between the osmolarity scores obtained from the TearLab™ and I-Pen® systems.

Assessment of the Effect of Wearing a Surgical Face Mask on Tear Film in Normal Eye Subjects.

Purpose: To assess the effect of wearing a face mask for a short time on the tear film parameters in normal eye subjects. Methods: Fifty-four normal eye subjects (14 female and 40 male) aged 18-40 years (23.8 ± 4.4 years) were recruited. A standardized patient evaluation of eye dryness was completed first, followed by noninvasive tear break-up time, phenol red thread, and tear ferning tests. A 5-minute gap was allowed between the tests. The subjects were asked to wear a surgical mask for one hour. The measurements were taken both before wearing a face mask and immediately after its removal. Results: Significant (Wilcoxon test) differences were found between the standardized patient evaluation of eye dryness (p=0.002) and the noninvasive tear break-up time scores (p < 0.001) before and after wearing face masks. No significant differences (Wilcoxon test, p > 0.05) were found between the phenol red thread scores and tear ferning grades before and after wearing face masks. Strong correlations (Spearman's rank correlation coefficient, r) were found among the standardized patient evaluation of eye dryness score (r = 0.590; p < 0.001), noninvasive tear break-up time measurements (r = 0.631; p < 0.001), and the tear ferning grades (r = 0.517; p < 0.001) before and after wearing the mask. A medium correlation (r = 0.377; p=0.005) was found between the noninvasive tear break-up time scores and tear ferning grades before wearing the mask. Conclusions: Wearing a surgical face mask for a short duration of one hour has an effect on ocular tear film in normal eye subjects. Dry eye symptoms and tear break-up increased after wearing a face mask compared with those experienced before wearing one.

Ultrastructural study of collagen fibrils, proteoglycans and lamellae of the cornea treated with iontophoresis - UVA cross-linking and hypotonic riboflavin solution.

To investigate the effects of iontophoresis-ultraviolet A (UVA) cross-linking (CXL) with hypotonic riboflavin solution on the ultrastructural changes in the lamellae, collagen fibrils (CFs), and proteoglycans (PGs) in the central and peripheral stroma of the human corneal buttons. The iontophoresis method was used for the trans-epithelial application of hypotonic riboflavin in ex vivo corneal culture for 5 min. The corneas were irradiated using three methods: Group 1 (G1) , a UVA irradiance of 3 mW/cm2 for 30 min; Group 2 (G2) , a UVA irradiance of 10 mW/cm2 for 9 min; Group 3 (G3) , without UVA irradiation. Three untreated corneas were used as controls ( G0 ). After the CXL procedure, the corneas were processed for electron microscopy. The CF diameter and PGs in each sample were analyzed using the iTEM program. The keratocyte organelles and stromal architecture in the peripheral cornea were better preserved than those in the central cornea. In G1 and G2, the mean CF diameter in the peripheral cornea was significantly higher than that in the central cornea. In G3, the CF diameter in the central cornea was significantly larger than that in the peripheral cornea. Furthermore, differences in PG area size were observed between the central and peripheral corneas in all groups. Riboflavin + UVA application at 3 mW/cm2 for 30 min and 10 mW/cm2 for 9 min was a suitable method of CXL; however, 3 mW/cm2 for 30 min improved the organization and size of the collagen fibrils. CXL treatment applied at the periphery was more effective than that applied at the center.