before the present composition , methods , and methodologies are described , it is to be understood that this invention is not limited to particular compositions , methods , and experimental conditions described , as such compositions , methods , and conditions may vary . it is also to be understood that the terminology used herein is for purposes of describing particular embodiments only , and is not intended to be limiting , since the scope of the present invention will be limited only in the appended claims . as used in this specification and the appended claims , the singular forms “ a ”, “ an ”, and “ the ” include plural references unless the context clearly dictates otherwise . thus , for example , references to “ a camera ” includes one or more cameras , and / or compositions of the type described herein which will become apparent to those persons skilled in the an upon reading this disclosure and so forth . unless defined otherwise , all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs . any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention , as it will be understood that modifications and variations are encompassed within the spirit and scope of the instant disclosure . as used herein , “ about ,” “ approximately ,” “ substantially ” and “ significantly ” will be understood by a person of ordinary skill in the art and will vary in some extent depending on the context in which they are used . if there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used , “ about ” and “ approximately ” will mean plus or minus & lt ; 10 % of particular term . “ substantially ” means to a great extent or degree . in embodiments , composition may “ contain ”, “ comprise ” or “ consist essentially of ” a particular component of group of components , where the skilled artisan would understand the latter to mean the scope of the claim is limited to the specified materials or steps “ and those that do not materially affect the basic and novel characteristic ( s )” of the claimed invention . as used herein “ ophthalmic systems ” are articles of manufacture that are designed to diagnose and assess vision health , and include , but are not limited to , retinal cameras , aberrometers , ophthalmoscopes , imaging systems , fundus camera , refraction systems , manual refractor , reflectometers , wavefront systems , tomographers , slit - lamp systems , phoroptors , perimeters , keratometers , head - anchored binoculars , tonometers , autorefractors , and optical coherence tomographers . as used herein , “ housing ” means a substantially enclosed case and support for a mechanism or article of manufacture . as used herein , “ rectangular ” means having right angles or a rectangular base , side , or sides . as used herein , “ parabolic ” means a two - dimensional , mirror - symmetrical curve , which is substantially u - shaped when viewed from the front . as used herein , “ anchor ” including grammatical variations thereof , means a device , composition or article that serves to hold an object firmly . for example , anchors include , but are not limited to , clips , velcro ®, screws , glue , fasteners , magnets , collars , nuts , hooks , tabs , straps , clamps , snaps and the like , which would be readily apparent to one of the skill in the art . as used herein . “ hood ” means a covering suspended over an object . as used herein , “ releaseably ”, including grammatical variations thereof , means configured to be freed from physical restraint or binding . as used herein , “ deflectable ”, including grammatical variations thereof , means capable of being turned aside , bend or deviate . for example , the deflectable plates as described herein may deviate 180 ° relative to the long axis of the base of the parabolic hood via a hinge . as used herein , “ thin sheet ” means a broad , substantially rectangular mass or piece of material relatively small in extent from one surface to the opposite in the smallest solid dimension . in embodiments , the parabolic hood may be made from one or more thin sheets , where the one or more thin sheets may comprise a polymer , a metal , a composite ( e . g ., wood , concrete , plastic reinforced by glass fibers , and graphite reinforced with carbon fibers and the like as would be apparent to one of skill in the art ), or a combination thereof . as used herein , “ opaque ” means that the object is neither transparent ( allowing all light to pass through ) nor translucent ( allowing some light to pass through ). many instruments , such as retinal cameras , are greatly affected by light and pupil size . pupil constrictions are affected by both light and accommodation . the device of the instant disclosure reduces light and diminishes accommodation . in embodiments , the device comprises a parabolic hood , which when installed on various optical instruments , significantly reduces depth of focus , and thereby reduces accommodation . in a related aspect , by reducing depth of focus in an eye that is occluded , both pupils will dilate fully . in a further related aspect , the parabolic hood may contain two ( 2 ) swinging screens that block depth of focus and reduce accommodation , thus , by reducing both light and accommodation stimulus , the pupils may dilate more effectively , allowing more facile and efficacious examination of the eye . the device , and methods of using said device , is described more fully below . fig1 shows the parabolic hood 10 illustrating an inner surface 101 , which may be matte or black , or the inner surface 101 may be modified to absorb light , and a clamping device 102 . while a clamping device 102 is shown , any means to anchor the parabolic hood 10 to an available surface may be substituted . for example , such means may include , but are not limited to , clips , velcro ®, screws , glue , fasteners , magnets , collars , nuts , hooks , tabs , clamps , snaps and the like , which would be readily apparent to one of the skill in the art . further , surfaces available on the instrument may include , but are not limited to , the top , bottom or side surfaces of the housing , the arms of a head rest , the arms of a chin rest or a combination thereof , as would be apparent to one of the skill in the art . while the anchors 102 as shown are releasable , the hood 10 may be permanently affixed to an ophthalmic instrument , where choice of surface may be left to artisan design . fig2 shows another embodiment of parabolic hood 11 illustrating the inner surface 101 , brace 103 , deflectable plate 104 , and clamps 102 . the deflectable plates 104 ( opposing plate not shown ) are attached to the parabolic hood 11 by a brace 103 which connects to a hinge 104 a , which is mechanically connected to the plates 104 ( although other means to connect the plates to the hood 11 may be used ). while plates 104 as shown are deflectable , it will be readily apparent that plates 104 may be custom designed to fit the contours of a housing 105 a ( refer to fig3 ), and plate 104 movement may be restricted in design . fig3 shows another embodiment of parabolic hood 10 / 11 illustrating the hood 10 / 11 mounted on to an ophthalmic instrument 105 ( e . g ., retinal cameral ). this embodiment shows that the hood 10 / 11 covers the housing 10 a and chin / head rest 107 of the device 105 , where the base of the hood 10 / 11 runs parallel with base 106 of the instrument 105 ( which is more clearly shown in fig4 and 5 ). while a retinal camera 105 is shown in fig3 , other instruments may be used with the basic hood design , including but not limited to , aberrometers , ophthalmoscopes , imaging systems , fundus camera , refraction systems , manual refractor , reflectometers , wavefront systems , tomographers , slit - lamp systems , phoroptors , perimeters , keratometers , head - anchored binoculars , tonometers , autorefractors , and optical coherence tomographers . further , while some instruments may not have a base , per se ( e . g ., head - anchored binoculars ), as long as the hood can be attached to the instrument so as to block light from above and lateral to the head of the subject being examined , efficacious positioning of the hood may be achieved in the absence of a true base . fig4 shows another embodiment of the parabolic hood 10 mounted on to an ophthalmic instrument 105 . in this view , a light collecting device 108 is illustrated , including a more detailed view of the chin / head rest 107 . fig5 shows the same perspective view of the system where a subject &# 39 ; s head 109 is positioned on the chin / head rest 107 , such that the subject &# 39 ; s eyes are aligned with the light collecting / projecting 108 device of the instrument 105 . as will be appreciated in view of the figures , once correctly positioned , the hood 10 / 1 i may cover the head of the subject 109 approximately mid - cranially , thus shielding the subject &# 39 ; s eyes from exposure to extraneous light . it will be appreciated that various of the above - disclosed and other features and functions , or alternatives thereof , may be desirably combined into many other different systems or applications . also various presently unforeseen or unanticipated alternatives , modifications , variations or improvements therein may be subsequently made by those skilled in the art , which are also intended to be encompassed by the following claims . unless specifically recited in a claim , steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order , number , position , size , shape , angle , color or material .
the present invention describes a rectangular parabolic hood for blocking accommodation and reducing depth of focus to offset the negative affects of extraneous light and visual stimulus during examination of the pupil using ophthalmic instruments .