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Localization of optic disc and fovea in retinal images using intensity based line scanning analysis

Kamble R, Kokare M, Deshmukh G, Hussin FA, Mériaudeau F

Comput Biol Med, 2017 08 01;87:382-396.
PMID: 28595892 DOI: 10.1016/j.compbiomed.2017.04.016

Accurate detection of diabetic retinopathy (DR) mainly depends on identification of retinal landmarks such as optic disc and fovea. Present methods suffer from challenges like less accuracy and high computational complexity. To address this issue, this paper presents a novel approach for fast and accurate localization of optic disc (OD) and fovea using one-dimensional scanned intensity profile analysis. The proposed method utilizes both time and frequency domain information effectively for localization of OD. The final OD center is located using signal peak-valley detection in time domain and discontinuity detection in frequency domain analysis. However, with the help of detected OD location, the fovea center is located using signal valley analysis. Experiments were conducted on MESSIDOR dataset, where OD was successfully located in 1197 out of 1200 images (99.75%) and fovea in 1196 out of 1200 images (99.66%) with an average computation time of 0.52s. The large scale evaluation has been carried out extensively on nine publicly available databases. The proposed method is highly efficient in terms of quickly and accurately localizing OD and fovea structure together compared with the other state-of-the-art methods.

Matched MeSH terms: Fovea Centralis/pathology*
Fulltext The magnitude of foveal suppression during fixation disparity in presbyopic patients

Abd-Manan F, Jenkins T, Kaye N

Malays J Med Sci, 2003 Jul;10(2):50-9.
PMID: 23386797

The characteristics of foveal suppression (FS) in fixation disparity (FD) due to visual stress were investigated and their relationship's between, age, symptoms, and the effect of temporary elimination of FD using prisms on the degree of the FS were analysed. Forty-five presbyopic subjects (15 without FD and 30 with stress related FD) participated in the study. The subjects underwent comprehensive optometric examination prior to the study. Their FS and FD were measured. The FD was later corrected with ophthalmic prisms, the power of which was equally divided between the eyes, and the FS was later verified. Age and FS had no significant correlation for subjects without FD (Spearman's rs = 0.17, p = 0.55, NS) and in subjects with FD (rs = 2.49, p = 0.19, NS), respectively. Correlation between the degree of FS and FD was weak (rs=0.38, p=0.07), however the magnitude of FD significantly increased with age (r=0.27, p=0.04). Subjects with FD had significantly larger degree of FS compared with subjects without FD (Wilcoxon's Z =-0.25, p=0.01). There was no significant difference in the magnitudes of FD (t = -0.38, p=0.07) and in their degrees of FS (Mann-Whitney U = 1.5, p=0.71) between subjects with and without symptoms. Correcting the FD with prisms generally reduced the degree of FS (Wilcoxon's Z =1.96, p=0.04), however, significant change in FS only occured in subjects with symptoms (Z=-1.97, p=0.03), but was not significant in subjects without symptoms (Z=-0.70, p=0.48).

Matched MeSH terms: Fovea Centralis
Identification and localization of fovea on colour fundus images using blur scales

Ganesan K, Acharya RU, Chua CK, Laude A

Proc Inst Mech Eng H, 2014 Sep;228(9):962-70.
PMID: 25234036 DOI: 10.1177/0954411914550847

Identification of retinal landmarks is an important step in the extraction of anomalies in retinal fundus images. In the current study, we propose a technique to identify and localize the position of macula and hence the fovea avascular zone, in colour fundus images. The proposed method, based on varying blur scales in images, is independent of the location of other anatomical landmarks present in the fundus images. Experimental results have been provided using the open database MESSIDOR by validating our segmented regions using the dice coefficient, with ground truth segmentation provided by a human expert. Apart from testing the images on the entire MESSIDOR database, the proposed technique was also validated using 50 normal and 50 diabetic retinopathy chosen digital fundus images from the same database. A maximum overlap accuracy of 89.6%-93.8% and locational accuracy of 94.7%-98.9% was obtained for identification and localization of the fovea.

Matched MeSH terms: Fovea Centralis/anatomy & histology; Fovea Centralis/pathology*
Fulltext Dengue related maculopathy and foveolitis

Juanarita J, Azmi MN, Azhany Y, Liza-Sharmini AT

Asian Pac J Trop Biomed, 2012 Sep;2(9):755-6.
PMID: 23570008 DOI: 10.1016/S2221-1691(12)60223-8

A 24 year-old Malay lady presented with high grade fever, myalgia, generalized rashes, severe headache and was positive for dengue serology test. Her lowest platelet count was 45 × 10(9) cells/L. She complained of sudden onset of painlessness, profound loss of vision bilaterally 7 days after the onset of fever. On examination, her right eye best corrected vision was 6/30 and left eye was 6/120. Her anterior segment examination was unremarkable. Funduscopy revealed there were multiple retinal haemorrhages found at posterior pole of both fundi and elevation at fovea area with subretinal fluid. Systemic examination revealed normal findings except for residual petechial rashes. She was managed conservatively. Her vision improved tremendously after 2 months. The retinal hemorrhages and foveal elevation showed sign of resolving. Ocular manifestations following dengue fever is rare. However, bilateral visual loss can occur if both fovea are involved.

Matched MeSH terms: Fovea Centralis/pathology
Analysis of foveal avascular zone in colour fundus images for grading of diabetic retinopathy severity

Ahmad Fadzil M, Ngah NF, George TM, Izhar LI, Nugroho H, Adi Nugroho H

Annu Int Conf IEEE Eng Med Biol Soc, 2010;2010:5632-5.
PMID: 21097305 DOI: 10.1109/IEMBS.2010.5628041

Diabetic retinopathy (DR) is a sight threatening complication due to diabetes mellitus that affects the retina. At present, the classification of DR is based on the International Clinical Diabetic Retinopathy Disease Severity. In this paper, FAZ enlargement with DR progression is investigated to enable a new and an effective grading protocol DR severity in an observational clinical study. The performance of a computerised DR monitoring and grading system that digitally analyses colour fundus image to measure the enlargement of FAZ and grade DR is evaluated. The range of FAZ area is optimised to accurately determine DR severity stage and progression stages using a Gaussian Bayes classifier. The system achieves high accuracies of above 96%, sensitivities higher than 88% and specificities higher than 96%, in grading of DR severity. In particular, high sensitivity (100%), specificity (>98%) and accuracy (99%) values are obtained for No DR (normal) and Severe NPDR/PDR stages. The system performance indicates that the DR system is suitable for early detection of DR and for effective treatment of severe cases.

Matched MeSH terms: Fovea Centralis/blood supply*
Determination of foveal avascular zone in diabetic retinopathy digital fundus images

Ahmad Fadzil MH, Izhar LI, Nugroho HA

Comput Biol Med, 2010 Jul;40(7):657-64.
PMID: 20573343 DOI: 10.1016/j.compbiomed.2010.05.004

Monitoring FAZ area enlargement enables physicians to monitor progression of the DR. At present, it is difficult to discern the FAZ area and to measure its enlargement in an objective manner using digital fundus images. A semi-automated approach for determination of FAZ using color images has been developed. Here, a binary map of retinal blood vessels is computer generated from the digital fundus image to determine vessel ends and pathologies surrounding FAZ for area analysis. The proposed method is found to achieve accuracies from 66.67% to 98.69% compared to accuracies of 18.13-95.07% obtained by manual segmentation of FAZ regions from digital fundus images.

Matched MeSH terms: Fovea Centralis/pathology*
Fulltext Retinotopic effects of visual attention revealed by dichoptic multifocal pupillography

Rosli Y, Carle CF, Ho Y, James AC, Kolic M, Rohan EMF, et al.

Sci Rep, 2018 02 14;8(1):2991.
PMID: 29445236 DOI: 10.1038/s41598-018-21196-1

Multifocal pupillographic objective perimetry (mfPOP) has recently been shown to be able to measure cortical function. Here we assessed 44 regions of the central 60 degrees of the visual fields of each eye concurrently in 7 minutes/test. We examined how foveally- and peripherally-directed attention changed response sensitivity and delay across the 44 visual field locations/eye. Four experiments were completed comparing white, yellow and blue stimulus arrays. Experiments 1 to 4 tested 16, 23, 9 and 6 subjects, 49/54 being unique. Experiment 1, Experiments 2 and 3, and Experiment 4 used three variants of the mfPOP method that provided increasingly improved signal quality. Experiments 1 to 3 examined centrally directed attention, and Experiment 4 compared effects of attention directed to different peripheral targets. Attention reduced the sensitivity of the peripheral locations in Experiment 1, but only for the white stimuli not yellow. Experiment 2 confirmed that result. Experiment 3 showed that blue stimuli behaved like white. Peripheral attention showed increased sensitivity around the attentional targets. The results are discussed in terms of the cortical inputs to the pupillary system. The results agree with those from multifocal and other fMRI and VEP studies. mfPOP may be a useful adjunct to those methods.

Matched MeSH terms: Fovea Centralis/physiology*
Application of different imaging modalities for diagnosis of Diabetic Macular Edema: A review

Mookiah MR, Acharya UR, Fujita H, Tan JH, Chua CK, Bhandary SV, et al.

Comput Biol Med, 2015 Nov 1;66:295-315.
PMID: 26453760 DOI: 10.1016/j.compbiomed.2015.09.012

Diabetic Macular Edema (DME) is caused by accumulation of extracellular fluid from hyperpermeable capillaries within the macula. DME is one of the leading causes of blindness among Diabetes Mellitus (DM) patients. Early detection followed by laser photocoagulation can save the visual loss. This review discusses various imaging modalities viz. biomicroscopy, Fluorescein Angiography (FA), Optical Coherence Tomography (OCT) and colour fundus photographs used for diagnosis of DME. Various automated DME grading systems using retinal fundus images, associated retinal image processing techniques for fovea, exudate detection and segmentation are presented. We have also compared various imaging modalities and automated screening methods used for DME grading. The reviewed literature indicates that FA and OCT identify DME related changes accurately. FA is an invasive method, which uses fluorescein dye, and OCT is an expensive imaging method compared to fundus photographs. Moreover, using fundus images DME can be identified and automated. DME grading algorithms can be implemented for telescreening. Hence, fundus imaging based DME grading is more suitable and affordable method compared to biomicroscopy, FA, and OCT modalities.

Matched MeSH terms: Fovea Centralis
Fulltext Evaluation of outer retinal layers in diabetic macula edema treated with intravitreal ranibizumab

Nur Aqilah, S., Wong, H.S., Syed Zulkifli, S.Z., Mushawiahti, M.

Medicine & Health, 2018;13(1):88-96.
MyJurnal

Anti-vascular endothelial growth factor (VEGF) reduces choroidal thickness by choroidal hypoperfusion in diabetic macula oedema (DME) patients. Indirect effect of anti-VEGF towards outer retinal layers (ORL) which supplied by choroidal circulation has not been well described. We evaluate the ORL thickness between retinal pigment epithelium (RPE) with inner-segment-outer-segment photoreceptor junction (IS/OS) and RPE with external limiting membrane (ELM) in pre- and postintravitreal Ranibizumab (IVR) treated eyes with central foveal diabetic macula edema. A total of 60 eyes (40 patients) were analysed. ORL thickness measured with optical coherence tomography at pre- and post-injection day 1, week 4 and week 6. Mean thickness of RPE-IS/OS was statistically significant over time (p=0.023) but not for RPE-ELM (p=0.216). Thickness ratio between RPE-IS/OS and RPE-ELM and central subfoveal thickness (CST) both showed statistically significant result over time with p=0.038 and p=0.000, respectively. We observed an initial reduction of ORL thickness at day 1 followed by increased in thickness at week 4 with subsequent reduction at week 6 was observed. ORL is an aspect that can be explore and emphasized further in patients considered for IVR injections. The long-term effects of IVR to the ORL however could not be concluded due to short follow up period.

Matched MeSH terms: Fovea Centralis
Fulltext Intravitreal ranibizumab in treating extensive traumatic submacular hemorrhage

Abdul-Salim I, Embong Z, Khairy-Shamel ST, Raja-Azmi MN

Clin Ophthalmol, 2013;7:703-6.
PMID: 23589678 DOI: 10.2147/OPTH.S42208

Herein, we report our experience in treating extensive traumatic submacular hemorrhage with a single dose of intravitreal ranibizumab. A 23-year-old healthy Malay man presented with a progressive reduction of central vision in the left eye of 2 days' duration following a history of blunt trauma. Visual acuity was reduced to counting fingers. Examination revealed infero-temporal subconjunctival hemorrhage, traumatic anterior uveitis, and an extensive sub-macular hemorrhage with suspicion of a choroidal rupture in the affected eye. He was initially treated conservatively with topical prednisolone acetate 1%. The subconjunctival hemorrhage and anterior uveitis resolved but his vision remained poor with minimal resolution of the submacular hemorrhage at 1 week follow-up (day 12 post-trauma). In view of the poor resolution of submacular hemorrhage, he was treated with a single dose of 0.5 mg intravitreal ranibizumab at day 20 post-trauma. At 4 weeks post-intravitreal ranibizumab, there was an improvement in visual acuity (from counting fingers to 6/45) and complete resolution of the submacular hemorrhage with presence of a choroidal rupture scar temporal to the fovea, which was not seen clearly at presentation due to obscuration by blood. His visual acuity further improved to 6/18 at 3 months post-trauma. Although this single case had a favorable outcome, a large population cohort study is needed to establish the effectiveness of intravitreal ranibizumab in treating extensive traumatic submacular hemorrhage.

Matched MeSH terms: Fovea Centralis
Fulltext Single intravitreal ranibizumab for myopic choroidal neovascularization

Nor-Masniwati S, Shatriah I, Zunaina E

Clin Ophthalmol, 2011;5:1079-82.
PMID: 21847340 DOI: 10.2147/OPTH.S21057

We report a case of myopic choroidal neovascularization that showed improvement after a single injection of ranibizumab. A 45-year-old Chinese man with high myopia presented with sudden onset painless central scotoma of his right eye of 2 weeks' duration. There was no history of trauma. His right eye vision on presentation was 6/30 which showed no improvement with pinhole. The right fundus showed myopic maculopathy at the posterior pole with subretinal hemorrhage at the inferotemporal fovea. The optic disc was tilted with inferotemporal peripapillary atrophy. There was a myopic maculopathy appearance in the macula of the left eye. Fundus fluorescein angiography revealed choroidal neovascularization at the fovea of the right eye. A diagnosis of right eye choroidal neovascularization secondary to myopic maculopathy was made. A single intravitreal injection of ranibizumab 0.05 mL was given. Ten weeks following intravitreal injection, vision had improved to 6/7.5, and repeated fundus fluorescein angiography showed absence of choroidal neovascularization. Follow-up at 6 months showed visual acuity had normalized to 6/6 with glasses, which was maintained up to 12 months following treatment. The right fundus showed no further subretinal hemorrhage with no new lesions.

Matched MeSH terms: Fovea Centralis
Fulltext Pneumatic retinopexy for treatment of posterior pole detachment following vitreoretinal surgery for diabetic tractional retinal detachment threatening the fovea

Bastion ML

BMJ Case Rep, 2012;2012.
PMID: 22878988 DOI: 10.1136/bcr-2012-006303

To describe the usage of 100% perfluoropropane and subsequent laser retinopexy for the repair of posterior pole retinal detachment in a previously vitrectomised patient with diabetic tractional detachment.

Matched MeSH terms: Fovea Centralis/pathology*
Subfoveal Choroidal Thickness in Pre-eclampsia

Sharudin SN, Saaid R, Samsudin A, Mohamad NF

Optom Vis Sci, 2020 02;97(2):81-85.
PMID: 32011579 DOI: 10.1097/OPX.0000000000001480

SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between subfoveal choroidal thickness (SFCT) and the parameters affecting the severity of pre-eclampsia has been reported. We provide evidence that SFCT is thicker in pre-eclamptic (PE) patients and speculate on the possible causes.
PURPOSE: The purposes of this study were to compare SFCT in PE, normal pregnant, and nonpregnant women using spectral domain optical coherence tomography and to correlate SFCT with severity of pre-eclampsia.
METHODS: A cross-sectional, observational study was performed. A total of 150 participants were divided into three groups: group 1 (50 PE women), group 2 (50 normal pregnant women), and group 3 (50 nonpregnant healthy women). Subfoveal choroidal thickness was measured using spectral domain optical coherence tomography. Other parameters including mean arterial blood pressure (MABP), central corneal thickness, macular thickness, IOP, ocular perfusion pressure (OPP), and urine protein-to-creatinine ratio were also measured. ANOVA and Pearson correlation analysis were used to look at differences between the groups. P < .05 was considered as statistically significant.
RESULTS: The MABP was higher in group 1 than in groups 2 and 3 (103.0 ± 12.9 vs. 83.2 ± 9.8 vs. 89.5 ± 7.2 mmHg, respectively; all P < .001). The SFCT of the PE group was higher than in groups 2 and 3 (370.7 ± 23.8 vs. 344.5 ± 30.8 vs. 315.8 ± 49.9 μm, respectively; all P < .001). There were no statistically significant differences in central corneal thickness, macular thickness, or IOP between the PE and healthy pregnant groups (all P > .05). The OPP was greater in PE patients (52.8 ± 8.5 vs. 41.9 ± 6.9 vs. 43.4 ± 5.2 mmHg, respectively; both P < .001). The SFCT was positively correlated with MABP (r = 0.464, P < .001), OPP (r = 0.495, P < .001), and urine protein-to-creatinine ratio (r = 0.635, P < .001) in the PE group.
CONCLUSIONS: Subfoveal choroidal thickness is higher in pre-eclampsia and is proportional to established markers of severity of the condition. This parameter might serve as a novel predictive marker for the severity of pre-eclampsia.

Matched MeSH terms: Fovea Centralis/physiopathology

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