MECHANISMS OF ACCOMMODATION 



EXTENT OF 

 ACCOMMODATION 



ACCESSORIES i^ 

 SUBSTITUTES 



REFRACTION* 



REMARKS 



oculomotor muscles 

 antagonize corneal? 



8D >8D 



[Lampetra fluviatilis) 



stenopoic pupis m 

 ra ys a Scyliiorhinus 



+I0-I5D 



I5-20D 



slit at ins root allows 

 transfer of aqueous 



lens-muscle present, 

 function not known 



small ciliary muscle, 

 function not known 



OS much OS -I5D 

 (in water) in good- 

 eyed 'i^^AAnabas, 

 OP in air) 



probably ordinarily 

 enough 1o overcome 



tne myopia 

 [Anabass\o accomm.) 



ste 



nopaic pup. 

 Encheliophi. 



c pupil in 



IS 



prob no ace (unless 

 in Neoceratodus) 



strictly aquatic spp. 

 OD in water-, amphib- 

 ious a terrestrial spp. 

 probably all OD in air 



never >5D (never e 

 nough to abolish the 

 hypermetropia of a 

 land sp. under water) 



pupillary nodules al- 

 low aqueous transfer 



probably have.no 

 gccomrnodation 



sphincter of iris 

 aids considerably 



OD,or nearly so, in air; 

 strong l y + in water 



nocturnal, but ossicles 

 retained (has a fovea!) 



probably never >2D 



nocturnal — ossicles 

 have been discarded 



stenopaic pupils 

 in most geckoes 



marine spp.OD in wo 

 ter. all others OD in air 



more than enough to 

 g ive emmetropio in i-izO 



OD 



great 



less ace. in marine a 

 strictly terrestrial s pp. 



Crompton's muscle 

 may 'sharpen' cornea 



pupil becomes 

 stenopaic in 



sea-snakes, when 

 out of water 



+ 2-9D 



0-17D 



muscle of accomm. 

 in iris derived from 

 Brucke's muscle 



>muscle cells in 

 chorioid 

 'focus' 'fove'cE 



Pf'n\^°P|(^/0/e^/??s myopic) 



great 



Crompton's muscle 

 increases focusing 

 power of cornea 



sphincter of ins 

 usually aids; often 

 'lens' in nictitans 



(penguins are — inairl 



very great 

 ) (cormorants: 40-50 D) 



kingfishers: a unique 

 occommodation-ob 

 viotinq device (tex 



stenopaic pupils, romp 

 retinae, in some (see 

 text); fruit-bat retina 



as much as +1D 

 (very small eyes, high +) 



usually little or none, 

 but may be up to4D 



[Dugong)-^[) in air, 

 ■ Strong l y + in water 



Brucke's muscle may 

 be present, but with 

 no a p parent function 



apparently none 



no ciliary muscle 



unknown 



toothed: presumably 

 considerable; baleen: 

 not more than 1/2-ID 



very powerful iris 

 s phincier aids greatl y 



OD 



more than enough to 

 g ive emmetropio in HzG 



in air, pupil is a slit, a 

 cancels astigmatism 



high myopia^. a c 

 neal astigmatism in 

 air, nullified by slit pupil 



enough to restore 

 emmetropio in water 



astigmatism elimin- 

 ated when under H20 



true normal +'/2D(?) 



about 10 Dot age 21 



highly variable (like 

 domesticated sp p.) 



stenopaic pupil 

 Tarsius 



'D,or OS high os+ID 

 .boPoons ore m yopic) 



not >IOD 



^D=diopters; +=hypermetropia; — = myopia; (zero)=emmet ropia 



273 



