Document Detail

Parasympathetic influences on emmetropization in chicks: evidence for different mechanisms in form deprivation vs negative lens-induced myopia.
MedLine Citation:
PMID:  22828050     Owner:  NLM     Status:  MEDLINE    
Ciliary ganglionectomy inhibits the development of myopia in chicks (Schmid et al., 1999), but has no effect on the compensatory responses to spectacle lenses (Schmid and Wildsoet, 1996). This study was done to assess the potential influence of the other parasympathetic input to the choroid, the pterygopalatine ganglia, on the choroidal and axial responses to retinal defocus, and to form deprivation. 4-5 week-old chicks had one of the following surgeries to one eye: (1) Section (X) of the autonomic part of cranial N VII (input to the pterygopalatine ganglia) (PPGX, n = 16), (2) PPGX plus ciliary ganglionectomy (PPG/CGX, n = 23) or (3) PPGX plus superior cervical ganglionectomy (PPG/SCGX, n = 10). Experimental eyes were fitted with positive or negative lenses, or diffusers, several days after surgery. In one group of PPG/CGX, eyes did not wear any devices (n = 8). Intact (no surgery) controls were done for all visual manipulations (lenses or diffusers). Sham surgeries were done for the PPG/CGX condition (n = 4). Ocular dimensions were measured using A-scan ultrasonography prior to the surgery, 5 days later when visual devices were placed on the eyes, at the end of lens- or diffuser-wear, and in the case of diffusers, 4 days after diffuser removal to look at "recovery". Refractive errors were measured using a Hartinger's refractometer. IOP was measured in 7 PPG/CGX birds 7d after surgery. PPGX/CGX resulted in choroidal thickening (125 μm) and a decrease in IOP over one week post-surgery. It also prevented the development of myopia in response to form deprivation (X vs intact: 0.2 D vs -4.1 D; p < 0.005), by preventing the increase in axial elongation (250 μm vs 670 μm/5d; p < 0.005). In fact, growth rate slowed below normal (X vs fellow eyes: 250 μm vs 489 μm/5d; p = 0.002). By contrast, there were no effects of this lesion on the development of myopia in response to negative lenses (X vs intact: -5.4 D vs -5.3 D). All three lesions inhibited the compensatory choroidal thickening in response to myopic defocus (ANOVA, p = 0.0008), but had no effect on the thinning response to hyperopic defocus. These results argue for different underlying mechanisms for the growth responses to form deprivation vs negative lens wear. They also imply that choroidal thickening and thinning are not opposing elements of a single mechanism.
Debora L Nickla; Falk Schroedl
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-07-22
Journal Detail:
Title:  Experimental eye research     Volume:  102     ISSN:  1096-0007     ISO Abbreviation:  Exp. Eye Res.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-03     Completed Date:  2012-12-04     Revised Date:  2013-09-03    
Medline Journal Info:
Nlm Unique ID:  0370707     Medline TA:  Exp Eye Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  93-103     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Elsevier Ltd. All rights reserved.
Department of Biosciences, The New England College of Optometry, Boston, MA 02115, United States.
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MeSH Terms
Axial Length, Eye / physiopathology
Choroid / pathology
Contact Lenses
Disease Models, Animal*
Emmetropia / physiology*
Eye / growth & development
Form Perception
Ganglia, Parasympathetic / physiology,  surgery
Intraocular Pressure
Myopia / physiopathology,  prevention & control*
Parasympathetic Nervous System / physiology*
Sensory Deprivation
Superior Cervical Ganglion / physiology,  surgery
Grant Support
NIH-NEI-013636//PHS HHS; R01 EY013636/EY/NEI NIH HHS

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