-
Developmental Dynamics : An Official... Jan 2018The developing eye-antennal disc of Drosophila melanogaster has been studied for more than a century, and it has been used as a model system to study diverse processes,... (Review)
Review
The developing eye-antennal disc of Drosophila melanogaster has been studied for more than a century, and it has been used as a model system to study diverse processes, such as tissue specification, organ growth, programmed cell death, compartment boundaries, pattern formation, cell fate specification, and planar cell polarity. The findings that have come out of these studies have informed our understanding of basic developmental processes as well as human disease. For example, the isolation of a white-eyed fly ultimately led to a greater appreciation of the role that sex chromosomes play in development, sex determination, and sex linked genetic disorders. Similarly, the discovery of the Sevenless receptor tyrosine kinase pathway not only revealed how the fate of the R7 photoreceptor is selected but it also helped our understanding of how disruptions in similar biochemical pathways result in tumorigenesis and cancer onset. In this article, I will discuss some underappreciated areas of fly eye development that are fertile for investigation and are ripe for producing exciting new breakthroughs. The topics covered here include organ shape, growth control, inductive signaling, and right-left symmetry. Developmental Dynamics 247:111-123, 2018. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Cell Differentiation; Drosophila Proteins; Drosophila melanogaster; Gene Expression Regulation, Developmental; Photoreceptor Cells, Invertebrate; Receptor Protein-Tyrosine Kinases; Retina; Signal Transduction
PubMed: 28856763
DOI: 10.1002/dvdy.24585 -
Korean Journal of Ophthalmology : KJO Jun 1997After the injection of about 10 gm of dapsone, a 38-year-old male showed a whitish-yellow patch in the macular region of both eyes, with decreased visual acuity of the...
After the injection of about 10 gm of dapsone, a 38-year-old male showed a whitish-yellow patch in the macular region of both eyes, with decreased visual acuity of the counting finger in the right and 0.04 in the left eye. Two weeks after the start of systemic steroid therapy the patch disappeared, and on follow-up at 11 months, visual acuity was 0.02 in the right and 0.08 in the left eye, with macular degeneration and foveal nonperfusion. This retinal damage seems to be ischemic in origin and to be caused by a combination of acute severe peripheral hypoxemia and the vascular obstructive effect of red cell fragmentation resulting from massive hemolysis.
Topics: Adult; Dapsone; Drug Overdose; Fluorescein Angiography; Follow-Up Studies; Fundus Oculi; Glucocorticoids; Humans; Leprostatic Agents; Macula Lutea; Macular Degeneration; Male; Methylprednisolone; Suicide, Attempted
PubMed: 9283157
DOI: 10.3341/kjo.1997.11.1.70 -
Romanian Journal of Ophthalmology 2021Idiopathic intracranial hypertension (IIH) is a neuro-ophthalmological syndrome of unknown cause that can be vision-threatening, so an early diagnosis is crucial. We...
Idiopathic intracranial hypertension (IIH) is a neuro-ophthalmological syndrome of unknown cause that can be vision-threatening, so an early diagnosis is crucial. We reported a case of a 68-year-old asymptomatic male referred with a cataract in his right eye (OD). Best-corrected visual acuity (BCVA) was 70 letters (20/ 40) in the OD and 85 letters (20/ 20) in the left eye (OS). Ophthalmological examination revealed a significant nuclear cataract in the OD that explained the visual acuity. Fundus imaging showed a faint nasal margin elevation of the optic disc of both eyes (OU). Optical coherence tomography (OCT) revealed a sectorial retinal nerve fiber layer (RNFL) atrophy in the inferior quadrant in the OS. Nevertheless, visual field (VF) did not demonstrate defects. Neuroimaging was normal and examination of CSF revealed an opening pressure of 500 mmH2O. A diagnosis of IIH was confirmed and acetazolamide 250 mg twice daily was recommended. After 12 months of follow-up, RNFL thickness remained stable and VF did not confirm defects. A routine eye examination was the onset of IIH in our case. Thus, the ophthalmologist played a crucial role in the early diagnosis of this syndrome. Papilledema is usually a key criterion for IIH, so after its detection, exclusion diagnosis and treatment should be initiated in order to avoid permanent visual loss.
Topics: Aged; Humans; Male; Optic Disk; Papilledema; Pseudotumor Cerebri; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 34179586
DOI: 10.22336/rjo.2021.37 -
BMJ Open Ophthalmology May 2022To investigate interexaminer reproducibility of non-cycloplegic subjective refractions. Subjective refractions are frequently determined, and it is important to know...
OBJECTIVE
To investigate interexaminer reproducibility of non-cycloplegic subjective refractions. Subjective refractions are frequently determined, and it is important to know whether differences in refractive state over time constitute meaningful, non-random change.
METHODS AND ANALYSIS
Fifty registered and experienced (≥5 years) optometrists from a single geographic region performed non-cycloplegic subjective refractions for a participant with moderate left eye(OS) to severe right eye (OD) ametropia. Subjective refractions were transformed to power matrices for analysis with stereopairs, distribution ellipsoids and polar profiles of variance of dioptric power. Absolute 95% limits of reproducibility ([Formula: see text](SD)) for excesses of subjective refractions for the right and left eyes separately from mean subjective refractions were determined.
RESULTS
Mean subjective refractions were -7.68-4.50×10 and -4.59-1.85×178 for the right and left eyes, respectively. The 95% absolute reproducibility limits for the stigmatic coefficients (spherical equivalents) were ≤1.71 D and ≤0.75 D for the right and left eyes, but corresponding limits for astigmatic coefficients were smaller (≤0.69 D).
CONCLUSION
Removal of possible outliers for OD and OS, respectively, reduces the absolute 95% reproducibility limits for the stigmatic and astigmatic coefficients to ≤0.97 D and ≤0.49 D, thus improving interexaminer reproducibility. However, these results suggest caution with analysis of refractive data where subjective rather than objective methods are applied for longitudinal and epidemiological studies.
Topics: Eye; Humans; Refraction, Ocular; Refractive Errors; Reproducibility of Results; Vision Tests
PubMed: 36161849
DOI: 10.1136/bmjophth-2021-000954 -
Graefe's Archive For Clinical and... Oct 2022To determine whether 24-h IOP monitoring can be a predictor for glaucoma progression and to analyze the inter-eye relationship of IOP, perfusion, and progression...
PURPOSE
To determine whether 24-h IOP monitoring can be a predictor for glaucoma progression and to analyze the inter-eye relationship of IOP, perfusion, and progression parameters.
METHODS
We extracted data from manually drawn IOP curves with HIOP-Reader, a software suite we developed. The relationship between measured IOPs and mean ocular perfusion pressures (MOPP) to retinal nerve fiber layer (RNFL) thickness was analyzed. We determined the ROC curves for peak IOP (T), average IOP(T), IOP variation (IOP), and historical IOP cut-off levels to detect glaucoma progression (rate of RNFL loss). Bivariate analysis was also conducted to check for various inter-eye relationships.
RESULTS
Two hundred seventeen eyes were included. The average IOP was 14.8 ± 3.5 mmHg, with a 24-h variation of 5.2 ± 2.9 mmHg. A total of 52% of eyes with RNFL progression data showed disease progression. There was no significant difference in T, T, and IOP between progressors and non-progressors (all p > 0.05). Except for T and the temporal RNFL, there was no correlation between disease progression in any quadrant and T, T, and IOP. Twenty-four-hour and outpatient IOP variables had poor sensitivities and specificities in detecting disease progression. The correlation of inter-eye parameters was moderate; correlation with disease progression was weak.
CONCLUSION
In line with our previous study, IOP data obtained during a single visit (outpatient or inpatient monitoring) make for a poor diagnostic tool, no matter the method deployed. Glaucoma progression and perfusion pressure in left and right eyes correlated weakly to moderately with each other.
Topics: Disease Progression; Glaucoma; Humans; Intraocular Pressure; Retina
PubMed: 35501491
DOI: 10.1007/s00417-022-05651-4 -
Journal of the American Veterinary... Dec 2020A 12-year-old neutered male domestic shorthair cat with chronic anterior uveitis and secondary glaucoma of the right eye was examined for persistent blepharospasm 2...
CASE DESCRIPTION
A 12-year-old neutered male domestic shorthair cat with chronic anterior uveitis and secondary glaucoma of the right eye was examined for persistent blepharospasm 2 weeks after corneal debridement and grid keratotomy for nonhealing superficial ulcerative keratitis.
CLINICAL FINDINGS
Examination of the right eye revealed a central superficial corneal ulcer associated with corneal epithelial and subepithelial infiltrates and mild aqueous flare. Structures consistent with amoeboid cysts and trophozoites were detected in the cornea by in vivo confocal microscopy. Suppurative keratitis was identified cytologically. An spp was isolated through culture and identified by a PCR assay of corneal specimens.
TREATMENT AND OUTCOME
Symptomatic and antiamoebic (polyhexamethylene biguanide 0.02% ophthalmic solution) treatments were instituted. Over the following 6 weeks, the cat lost vision in the affected eye and lesions progressed to nonulcerative stromal keratitis associated with a dense paracentral corneal stroma ring infiltrate and anterior lens luxation. The globe was enucleated, and lymphoplasmacytic sclerokeratitis, anterior uveitis, and retinal detachment were noted. organisms were detected within the corneal stroma and anterior sclera with histologic and immunohistochemical stains. The amoebae were classified to the T4 genotype by DNA sequencing. The cat had no medical problems attributed to infection over 36 months after enucleation, until the cat was lost to follow-up.
CLINICAL RELEVANCE
Naturally acquired sclerokeratitis is described in a cat for the first time. infection should be considered for cats with superficial corneal disease refractory to appropriate treatments and especially occurring after ocular trauma, including keratotomy.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Animals; Cat Diseases; Cats; Cornea; Corneal Stroma; Corneal Ulcer; Male
PubMed: 33269959
DOI: 10.2460/javma.257.12.1280 -
Sensors (Basel, Switzerland) Nov 2021To quantify the effect of levelling the corneal surface around the optical axis on the calculated values of corneal asphericity when conic and biconic models are used...
To quantify the effect of levelling the corneal surface around the optical axis on the calculated values of corneal asphericity when conic and biconic models are used to fit the anterior corneal surface. This cross-sectional study starts with a mathematical simulation proving the concept of the effect that the eye's tilt has on the corneal asphericity calculation. Spherical, conic and biconic models are considered and compared. Further, corneal asphericity is analysed in the eyes of 177 healthy participants aged 35.4 ± 15.2. The optical axis was determined using an optimization procedure via the Levenberg-Marquardt nonlinear least-squares algorithm, before fitting the corneal surface to spherical, conic and biconic models. The influence of pupil size (aperture radii of 1.5, 3.0, 4.0 and 5.0 mm) on corneal radius and asphericity was also analysed. In computer simulations, eye tilt caused an increase in the apical radii of the surface with the increase of the tilt angle in both positive and negative directions and aperture radii in all models. Fitting the cornea to spherical models did not show a significant difference between the raw-measured corneal surfaces and the levelled surfaces for right and left eyes. When the conic models were fitted to the cornea, changes in the radii of the cornea among the raw-measured corneal surfaces' data and levelled data were not significant; however, significant differences were recorded in the asphericity of the anterior surfaces at radii of aperture 1.5 mm ( < 0.01). With the biconic model, the posterior surfaces recorded significant asphericity differences at aperture radii of 1.5 mm, 3 mm, 4 mm and 5 mm ( = 0.01, < 0.01, < 0.01 & < 0.01, respectively) in the nasal temporal direction of right eyes and left eyes ( < 0.01, < 0.01, < 0.01 & < 0.01, respectively). In the superior-inferior direction, significant changes were only noticed at aperture radii of 1.5 mm for both right and left eyes ( = 0.05, < 0.01). Estimation of human corneal asphericity from topography or tomography data using conic and biconic models of corneas are affected by eyes' natural tilt. In contrast, the apical radii of the cornea are less affected. Using corneal asphericity in certain applications such as fitting contact lenses, corneal implant design, planning for refractive surgery and mathematical modelling when a geometrical centre of the eye is needed should be implemented with caution.
Topics: Cornea; Corneal Topography; Cross-Sectional Studies; Humans; Mathematics; Models, Theoretical
PubMed: 34833714
DOI: 10.3390/s21227636 -
Scientific Reports Jun 2022In a previous study, we identified biocular asymmetries in fundus photographs, and macula was discriminative area to distinguish left and right fundus images...
In a previous study, we identified biocular asymmetries in fundus photographs, and macula was discriminative area to distinguish left and right fundus images with > 99.9% accuracy. The purposes of this study were to investigate whether optical coherence tomography (OCT) images of the left and right eyes could be discriminated by convolutional neural networks (CNNs) and to support the previous result. We used a total of 129,546 OCT images. CNNs identified right and left horizontal images with high accuracy (99.50%). Even after flipping the left images, all of the CNNs were capable of discriminating them (DenseNet121: 90.33%, ResNet50: 88.20%, VGG19: 92.68%). The classification accuracy results were similar for the right and left flipped images (90.24% vs. 90.33%, respectively; p = 0.756). The CNNs also differentiated right and left vertical images (86.57%). In all cases, the discriminatory ability of the CNNs yielded a significant p value (< 0.001). However, the CNNs could not well-discriminate right horizontal images (50.82%, p = 0.548). There was a significant difference in identification accuracy between right and left horizontal and vertical OCT images and between flipped and non-flipped images. As this could result in bias in machine learning, care should be taken when flipping images.
Topics: Fundus Oculi; Machine Learning; Macula Lutea; Neural Networks, Computer; Tomography, Optical Coherence
PubMed: 35705663
DOI: 10.1038/s41598-022-14140-x -
Philosophical Transactions of the Royal... Oct 2001The shared roles of Pax6 and Six homologues in the eye development of various bilaterians suggest that Urbilateria, the common ancestors of all Bilateria, already... (Review)
Review
The shared roles of Pax6 and Six homologues in the eye development of various bilaterians suggest that Urbilateria, the common ancestors of all Bilateria, already possessed some simple form of eyes. Here, we re-address the homology of bilaterian cerebral eyes at the level of eye anatomy, of eye-constituting cell types and of phototransductory molecules. The most widespread eye type found in Bilateria are the larval pigment-cup eyes located to the left and right of the apical organ in primary, ciliary larvae of Protostomia and Deuterostomia. They can be as simple as comprising a single pigment cell and a single photoreceptor cell in inverse orientation. Another more elaborate type of cerebral pigment-cup eyes with an everse arrangement of photoreceptor cells is found in adult Protostomia. Both inverse larval and everse adult eyes employ rhabdomeric photoreceptor cells and thus differ from the chordate cerebral eyes with ciliary photoreceptors. This is highly significant because on the molecular level we find that for phototransduction rhabdomeric versus ciliary photoreceptor cells employ divergent rhodopsins and non-orthologous G-proteins, rhodopsin kinases and arrestins. Our comparison supports homology of cerebral eyes in Protostomia; it challenges, however, homology of chordate and non-chordate cerebral eyes that employ photoreceptor cells with non-orthologous phototransductory cascades.
Topics: Animals; Axons; Biological Evolution; Chordata, Nonvertebrate; Eye; Larva; Ocular Physiological Phenomena; Photoreceptor Cells, Invertebrate; Photoreceptor Cells, Vertebrate; Phylogeny; Pigments, Biological; Signal Transduction
PubMed: 11604122
DOI: 10.1098/rstb.2001.0971 -
PloS One 2020To assess the axial, radial and tangential limbus position misrepresentation when parametric models are used to represent the cornea and the sclera.
PURPOSE
To assess the axial, radial and tangential limbus position misrepresentation when parametric models are used to represent the cornea and the sclera.
METHODS
This retrospective study included 135 subjects aged 22 to 65 years (36.5 mean ±9.8 STD), 71 females and 64 males. Topography measurements were taken using an Eye Surface Profiler topographer and processed by a custom-built MATLAB code. Eye surfaces were freed from edge-effect artefacts and fitted to spherical, conic and biconic models.
RESULTS
When comparing the radial position of the limbus, average errors of -0.83±0.19mm, -0.76±0.20mm and -0.69±0.20mm were observed within the right eye population for the spherical, conic and biconic models fitted up to 5mm. For the same fitting radius, the average fitting errors were -0.86±0.23mm, -0.78±0.23mm and -0.73±0.23mm for the spherical, conic and biconic models respectively within the left eye population. For the whole cornea fit, the average errors were -0.27±0.12mm and -0.28±0.13mm for the spherical models, -0.02±0.29mm and -0.05±0.27mm for the conic models, and -0.22±0.16mm and 0.24±0.17mm for the biconic models in the right and left eye populations respectively.
CONCLUSIONS
Through the use of spherical, conic and biconic parametric modelling methods, the eye's limbus is being mislocated. Additionally, it is evident that the magnitude of fitting error associated with the sclera may be propagating through the other components of the eye. This suggests that a corneal nonparametric model may be necessary to improve the representation of the limbus.
Topics: Adult; Aged; Algorithms; Cornea; Corneal Topography; Female; Humans; Male; Middle Aged; Models, Anatomic; Retrospective Studies; Sclera; Young Adult
PubMed: 32970690
DOI: 10.1371/journal.pone.0236096