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Event: 1878

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Decreased, Eye size

Short name
The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. More help
Decreased, Eye size
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Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help
Level of Biological Organization

Organ term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help
Organ term

Key Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling).  The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor).  Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description.  To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons.  If a desired term does not exist, a new term request may be made via Term Requests.  Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help
Process Object Action
microphthalmia eye decreased

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE. Clicking on the name of the AOP will bring you to the individual page for that AOP. More help
AOP Name Role of event in AOP Point of Contact Author Status OECD Status
TPOi eye size KeyEvent Lucia Vergauwen (send email) Under development: Not open for comment. Do not cite Under Development
Inhibition of Fyna leading to increased mortality KeyEvent Vid Modic (send email) Open for citation & comment

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KE.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help
Term Scientific Term Evidence Link
zebrafish Danio rerio NCBI

Life Stages

An indication of the the relevant life stage(s) for this KE. More help
Life stage Evidence
Larval development

Sex Applicability

An indication of the the relevant sex for this KE. More help

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

Animals show a wide variation in relative eye size (compared to body size) both within and between species. Eye size is directly related to visual ability. Eye size, and in particular the eye to body ratio, gives a lot of information about the quality of vision of the individual but also about its lifestyle. For example, eye size provides information on nocturnal and diurnal lifestyles in mammals (Kirk, 2006). Previous studies of eye design suggest a common organizing principle about how the activity pattern is reflected in the size and shape of the eyes (Hall, 2008).

Large eyes generally have greater visual sensitivity as they have relatively large corneas and lenses, e.g. in primates (e.g (Kirk, 2006; Ross and Kirk, 2007), birds (e.g (Brooke et al., 1999; Hall, 2008), lizards (Hall, 2008), fish (e.g. (Bejarano-Escobar et al., 2010; Karvonen and Seppälä, 2008) and other species. Increasing the size of the whole eye can increase resolution or sensitivity without having to decrease the other. For example, a larger eye with a longer focal length may be more sensitive without loss of acuity, or it may be more acute without loss of sensitivity. However, a constraint for large eyes is that they must always fit inside an animal's head and are associated with increased development and maintenance costs (Caves et al., 2017).

Microphthalmia is a congenital ocular deformation characterized by abnormally small eyes, with or without structural abnormalities (Le et al., 2012). Microphthalmia can occur as a consequence of a number of potential mechanisms, including but not limited to general developmental delay, increased cell death, reduced cell proliferation, and reduced cell differentiation within the developing eye (Stenkamp et al., 2002).

How It Is Measured or Detected

A description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements.These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help
  • Use of plasticine spherical ball (Brooke et al., 1999)
  • Ocular biometry (Kang and Wildsoet, 2016)
  • Relative eye size: larger corneal diameters relative to the axial length or larger eye diameter relative to body length (Baumann et al., 2016; Hall, 2008) determined by morphological analysis with electromicroscopy or analysis of digital images
  • Morphological live imaging + Aqueous outflow tract visualization (Chawla et al., 2018)

Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided).  More help

Taxonomic applicability: Applicable to a large range of species. For instance, eye length is positively correlated with visual acuity across mammals  (Heesy and Hall 2010; Veilleux and Kirk 2014), birds (Hall and Heesy 2011), and  fishes (Baumann et al., 2016; Caves et al., 2017; Corral-López et al., 2017).

Sex applicability: Difference in male/female probably due to general differences in body size, highlighted by some studies (Corral-López et al., 2017; Svanbäck and Johansson, 2019).


List of the literature that was cited for this KE description. More help

Baumann, L., Ros, A., Rehberger, K., Neuhauss, S.C.F., Segner, H., 2016. Thyroid disruption in zebrafish (Danio rerio) larvae: Different molecular response patterns lead to impaired eye development and visual functions. Aquat. Toxicol. 172, 44–55.

Bejarano-Escobar, R., Blasco, M., DeGrip, W.J., Oyola-Velasco, J.A., Martín-Partido, G., Francisco-Morcillo, J., 2010. Eye development and retinal differentiation in an altricial fish species, the senegalese sole (Solea senegalensis, Kaup 1858). J. Exp. Zool. Part B Mol. Dev. Evol. 314 B, 580–605.

Brooke, M.D.L., Hanley, S., Laughlin, S.B., 1999. The scaling of eye size with body mass in birds. Proc. R. Soc. B Biol. Sci. 266, 405–412.

Caves, E.M., Sutton, T.T., Johnsen, S., 2017. Visual acuity in ray-finned fishes correlates with eye size and habitat. J. Exp. Biol. 220, 1586–1596.

Chawla, B., Swain, W., Williams, A.L., Bohnsack, B.L., 2018. Retinoic acid maintains function of neural crest–derived ocular and craniofacial structures in adult zebrafish. Investig. Ophthalmol. Vis. Sci. 59, 1924–1935.

Corral-López, A., Garate-Olaizola, M., Buechel, S.D., Kolm, N., Kotrschal, A., 2017. On the role of body size, brain size, and eye size in visual acuity. Behav. Ecol. Sociobiol. 71.

Hall, M.I., 2008. Comparative analysis of the size and shape of the lizard eye. Zoology 111, 62–75.

Kang, P., Wildsoet, C.F., 2016. Acute and short-term changes in visual function with multifocal soft contact lens wear in young adults. Contact Lens Anterior Eye 39, 133–140.

Karvonen, A., Seppälä, O., 2008. Eye fluke infection and lens size reduction in fish: A quantitative analysis. Dis. Aquat. Organ. 80, 21–26.

Kashyap, B., Frederickson, L.C., & Stenkamp, D.L., 2008. Mechanisms for persistent microphthalmia following ethanol exposure during retinal neurogenesis in zebrafish embryos. Vis. Neurosci. 24(3), 409–421.

Kirk, E.C., 2006. Effects of activity pattern on eye size and orbital aperture size in primates. J. Hum. Evol. 51, 159–170.

Le, H.G., Dowling, J.E., & Cameron, D.J., 2012. Early retinoic acid deprivation in developing zebrafish results in microphthalmia. Vis. Neurosci. 29(4–5), 219–228.

Marsh-Armstrong, N., Mccaffery, P., Gilbert, W., Dowling, J.E., & Dräger, U.C., 1994. Retinoic acid is necessary for development of the ventral retina in zebrafish. Proc. Natl. Acad. Sci. U S A. 91(15), 7286–7290.

Ross, C.F., Kirk, E.C., 2007. Evolution of eye size and shape in primates. J. Hum. Evol. 52, 294–313.

Stenkamp, D.L., Frey, R.A., Mallory, D.E., & Shupe, E.E., 2002. Embryonic Retinal Gene Expression in Sonic-You Mutant Zebrafish. Dev. Dyn., 225, 344–350.

Svanbäck, R., Johansson, F., 2019. Predation selects for smaller eye size in a vertebrate: Effects of environmental conditions and sex. Proc. R. Soc. B Biol. Sci. 286.

Wold, M., Beckmann, M., Poitra, S., Espinoza, A., Longie, R., Mersereau, E., Darland, D.C., Darland, T., 2017. The longitudinal effects of early developmental cadmium exposure on conditioned place preference and cardiovascular physiology in zebrafish. Aquat. Toxicol. 191, 73–84.