Training eyes
Practising the basic principles of imaging and photographing the eye is made much easier using training devices such as those illustrated below.
Two types of training eyes are described below ,the first can be manufactured in short order with minimal equipment whilst the second are multi-part 3D printed devices.
Below is a copy of a presentation I gave to the lovely bunch of vets at the IEOC in Iceland (June 2018). Please get in contact if you have any comments, queries or suggestions.
Please get in touch if you are struggling to source appropriate lens and cabachons or if need iris or retinal images to print out.
Best wishes
Tim
Two types of training eyes are described below ,the first can be manufactured in short order with minimal equipment whilst the second are multi-part 3D printed devices.
Below is a copy of a presentation I gave to the lovely bunch of vets at the IEOC in Iceland (June 2018). Please get in contact if you have any comments, queries or suggestions.
Please get in touch if you are struggling to source appropriate lens and cabachons or if need iris or retinal images to print out.
Best wishes
Tim
1) "Easy" training eye
Shopping list:
1) a 50mm diameter children's "play pit ball"
2) a 50mm focal length converging lens e.g.
a) 1x 20Dioptre indirect lens
b) 1x 50mm diameter 50 mm focal length bi convex converging lens ( theses are sold widely for educational optics experiments for schools and can be readily found on eBay, Amazon or via a specialist lens supplier or
c) 2x 50mm diameter cabochons/glass domes - these are readily available for jewellery and projects. Placed flat side to flat side two 50mm diameter glass cabochons form a biconvex converging lens with an approximate focal length of 50mm.
3) Cardboard tube cut to form a carrier for the lens to allow it to be secured to the plastic "globe"
4) A printed retinal image
1) a 50mm diameter children's "play pit ball"
2) a 50mm focal length converging lens e.g.
a) 1x 20Dioptre indirect lens
b) 1x 50mm diameter 50 mm focal length bi convex converging lens ( theses are sold widely for educational optics experiments for schools and can be readily found on eBay, Amazon or via a specialist lens supplier or
c) 2x 50mm diameter cabochons/glass domes - these are readily available for jewellery and projects. Placed flat side to flat side two 50mm diameter glass cabochons form a biconvex converging lens with an approximate focal length of 50mm.
3) Cardboard tube cut to form a carrier for the lens to allow it to be secured to the plastic "globe"
4) A printed retinal image
| Equine iris images to print out for training eyes (50mm) |
| Equine fundus image - cut out and then make 4 radial cuts to allow folding into ball |
2) 3D printed training eyes: free to download and use
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The following three models were designed to mimic the equine and small animal eye for the training of Veterinary Surgeons and students in the art and science of ophthalmoscopy and ophthalmic photography.
The training models requires 2x glass cabochons (glass domes - used for jewellery making, freely available e.g Amazon, eBay) to construct the anterior chamber/lens simulacrum. Placed together, flat surface to flat surface, they create a spherical lens. A pair of 50mm diameter cabachons creates a lens of approximately 20 Dioptre focal length and is used for the equine training model whilst a pair of 30mm cabochons creates a lens of approximately 30Dioptre focal length and is used for the simplest (vers 1) small animal model. Acrylic lenses of specific focal length are needed for the more complex vers 2 training eye, get in touch if you need help sourcing at [email protected].
Simulated iris/pupils are either 3D printed or printed on paper and then sandwiched between the two cabochons. The assembled lens/iris/anterior chamber is then rested on the retaining ring at the top of the model. The lid is placed on top to secure the lenses.
A retinal image is printed onto photographic paper approx. and the retinal image placed in to the slot at the bottom of the models.
Opaque and translucent lens and corneal lesions can be simulated using white correction liquid (Tipex) or marker pens. Lesions can be painted on to the surface of the 3D printed iris simulacra or alternatively iris simulacra can be printed and the pupil cut out.
The training models requires 2x glass cabochons (glass domes - used for jewellery making, freely available e.g Amazon, eBay) to construct the anterior chamber/lens simulacrum. Placed together, flat surface to flat surface, they create a spherical lens. A pair of 50mm diameter cabachons creates a lens of approximately 20 Dioptre focal length and is used for the equine training model whilst a pair of 30mm cabochons creates a lens of approximately 30Dioptre focal length and is used for the simplest (vers 1) small animal model. Acrylic lenses of specific focal length are needed for the more complex vers 2 training eye, get in touch if you need help sourcing at [email protected].
Simulated iris/pupils are either 3D printed or printed on paper and then sandwiched between the two cabochons. The assembled lens/iris/anterior chamber is then rested on the retaining ring at the top of the model. The lid is placed on top to secure the lenses.
A retinal image is printed onto photographic paper approx. and the retinal image placed in to the slot at the bottom of the models.
Opaque and translucent lens and corneal lesions can be simulated using white correction liquid (Tipex) or marker pens. Lesions can be painted on to the surface of the 3D printed iris simulacra or alternatively iris simulacra can be printed and the pupil cut out.
Small animal training eye (SATE) Version 1
This version is simplest and cheapest to print and can be set up both in anterior mode for simulating lens lesions and posterior segment mode for practising fundoscopy. The tubular body shape means that the walls of the model body are visible during fundoscopy and it is more difficult to demonstrate peripheral retinal examination techniques.
3 x 30mm glass cabachons required. 1 to mimic the anterior chamber, 1 to mimic the clear lens and a third which can painted with white cataract lesions.
Download instructions for use here.
Download 3d print files below
3 x 30mm glass cabachons required. 1 to mimic the anterior chamber, 1 to mimic the clear lens and a third which can painted with white cataract lesions.
Download instructions for use here.
Download 3d print files below
| small animal training eye (30mm lens) STL format |
Large animal training eye (LATE)
This version is designed to mimic the large equine globe and uses a 50mm focal length (20 dioptre)biconvex lens. These lenses are readily available from educational suppliers for optics experiments. Despite not being aspherical these same lenses work well as a cheap indirect lens for training indirect ophthalmosopy and we have used these for many years as training lenses. They are less forgiving of poor positioning than aspherical 20D lenses but this can be helpful during training to ensure best technique.
They can be set up both in anterior mode for simulating lens lesions and posterior segment mode for practising fundoscopy. As with the version 1 small animal model the tubular body shape means that the walls of the model body are visible during fundoscopy and it is more difficult to demonstrate peripheral retinal examination techniques.
2 x 50mm glass cabachons required. 1 to mimic the anterior chamber, 1 which can painted with white cataract lesions.
1x 50mm biconvex 20D lens for use in posterior segment mode for fundoscopy training. (2 clear 50mm cabachons can be used instead if no 20D lenses available_.
Download instructions for use here.
Download 3d print files below
They can be set up both in anterior mode for simulating lens lesions and posterior segment mode for practising fundoscopy. As with the version 1 small animal model the tubular body shape means that the walls of the model body are visible during fundoscopy and it is more difficult to demonstrate peripheral retinal examination techniques.
2 x 50mm glass cabachons required. 1 to mimic the anterior chamber, 1 which can painted with white cataract lesions.
1x 50mm biconvex 20D lens for use in posterior segment mode for fundoscopy training. (2 clear 50mm cabachons can be used instead if no 20D lenses available_.
Download instructions for use here.
Download 3d print files below
| equine training eye STL format |
Small animal training eye large fundus version (SATE version 2)
This is the newest version and can be used for teaching both small and large animal ophthalmoscopy. The cone shaped body means that a truer indirect image is obtained and peripheral retinal examination techniques can be demonstrated. It requires more preparation after printing and an aspheric acrylic lens (25mm diameter 45mm focal length) needs to be sourced (get in touch for more details) and glued in to the posterior segment lid for fundic examination.
In anterior segment mode two 30mm cabochons are used, one to mimic the anterior chamber and a second with anterior and posterior axial and peripheral lesions painted to mimic cataract. The anterior segment lid is used to hold the lenses in place. He is wearing a pair of glasses to remind us he needs two lenses in this mode.
The larger more complex lid is used both in posterior mode (for teaching fundoscopy) and corneal mode (for teaching corneal examination). There is a single 45mm FL acrylic lens glued in to the lid. It is important to use glues which do not damage acrylic lenses e.g. E6000 or B7000 glues. The slot in this lid is designed to hold a standard microscope slide which is painted with clear and coloured nail lacquers to mimic superficial corneal ulcers, linear keratopathy lesions, keratic precipitates etc. When the slide is in place the techniques of retro-illumination and distant direct ophthalmoscopy can be demonstrated. This lid is wearing a monocle to remind us that he only needs one lens to be used,
Finally a stand is included to allow comfortable use when seated.
Each of the 5 components illustrated.
Download 3D print files below.
In anterior segment mode two 30mm cabochons are used, one to mimic the anterior chamber and a second with anterior and posterior axial and peripheral lesions painted to mimic cataract. The anterior segment lid is used to hold the lenses in place. He is wearing a pair of glasses to remind us he needs two lenses in this mode.
The larger more complex lid is used both in posterior mode (for teaching fundoscopy) and corneal mode (for teaching corneal examination). There is a single 45mm FL acrylic lens glued in to the lid. It is important to use glues which do not damage acrylic lenses e.g. E6000 or B7000 glues. The slot in this lid is designed to hold a standard microscope slide which is painted with clear and coloured nail lacquers to mimic superficial corneal ulcers, linear keratopathy lesions, keratic precipitates etc. When the slide is in place the techniques of retro-illumination and distant direct ophthalmoscopy can be demonstrated. This lid is wearing a monocle to remind us that he only needs one lens to be used,
Finally a stand is included to allow comfortable use when seated.
Each of the 5 components illustrated.
Download 3D print files below.
| sate_vers_2_large_fundus.zip |
Body - print with supports.
Base - glue body to ensuring paper retinal images can slide easily,
Model stand,
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Posterior lid - print with tree supports for best results. A steel 12inch ruler is useful for removing supports from the slot.
Anterior segment mode lid - print in this orientation with supports.
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