Workup
Other Tests
Determination of the lens formula is as follows:
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Van der Heijde's nomogram for iris claw lens power calculation
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Feingold's formula (proprietary) for a precrystalline lens implant
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Matrix formula for phakic anterior chamber intraocular lens (AC IOL) power calculation
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Binkhorst 2 formula for posterior chamber intraocular lens (PC IOL) power calculation
Media Gallery
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Phakic myopia lens of -20.0 diopters, 7 years postoperatively, in a 30-year-old man. There is slight upward decentration. The lens appears well tolerated.
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The drawing shows the relation of the phakic iris claw lens to the surrounding structures. Courtesy of Professor Jan J. F. Worst, MD.
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Slit lamp photograph of optical section of the anterior segment showing a gap between the anterior surface of the crystalline lens and the posterior surface of the implanted myopia iris claw lens. Courtesy of Professor Jan J. F. Worst, MD.
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Phakic minus iris claw lens, 12 years postoperatively, in a 36-year-old patient shown in 3D. The lens is seen to sit on top of the iris cone. This picture helps to understand why the much larger angle-supported lenses have to be vaulted by 20° to keep clear of the iris.
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Phakic myopia iris claw lens, 11 years postoperatively. The claws of the lens are shifted upwards. This configuration makes iris fixation in the claws easier at the time of surgery. It reduces the chances of pressure by the lens haptics and the optic on the natural lens and the iris, in case a bigger knuckle of iris is drawn inside the claw.
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Anterior segment fluorescein angiography in a case of iris claw lens (Artisan lens) in a phakic myope. There is no dye leakage. Courtesy of Professor Jan J. F. Worst, MD.
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5-mm optic Artisan lens. Courtesy of Professor Jan J. F. Worst, MD.
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6-mm diameter optic, Artisan lens. Courtesy of Professor Jan J. F. Worst, MD.
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This 64-year-old patient had an iris claw lens implanted in his aphakic eye on the posterior surface of the iris, 10 years ago. The white line represents the pupil in its normal state. Note fine pigment on the surface of the intraocular lens in this area. Bigger pigment granules are seen in the periphery. It seems that the pigment dispersed as a result of friction between the anterior surface of the intraocular lens and the posterior surface of the iris, over a very long time. This happened in spite of the fact that the posterior chamber was very roomy due to aphakia. Courtesy of Kiranjit Singh, MD.
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Gonioscopy in the same patient as in Image 9 with iris claw lens fixed to the back of the iris. The angle shows severe pigmentation of the angle of the anterior chamber. Only the very finely pulverized pigment is deposited in the angle. Courtesy of Kiranjit Singh, MD.
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Gonioscopy in 3D of the other eye of the same patient as in Image 9 that received anteriorly fixed iris claw lens in the aphakic eye, 11 years ago. There is total absence of pigmentation in the angle of the anterior chamber. Courtesy of Kiranjit Singh, MD.
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Postmortem appearances in an eye with an iris claw lens showing the ciliary body and the posterior surface of the iris. There is a total lack of inflammatory or degenerative changes. Courtesy of Professor Jan J. F. Worst, MD.
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Besides producing optical problems, a decentered phakic intraocular lens, by taking the haptics closer to the limbus, makes the eye vulnerable to intermittent endothelial touch whenever the eye is forcibly rubbed. It can be prevented by a careful fixation during surgery. The decentered lens can be managed by opening the claws and refixation at the right place. Courtesy of Professor Jan J. F. Worst, MD.
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Eleven years after phakic minus iris claw lens implantation in a 35-year-old patient, the pupil has been dilated for fundus examination. Iris claw lens does not affect the movements of the iris and the pupil, except at the point where the iris passes through the claw. The crystalline lens is not affected since the implanted lens remains far away from it.
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This phakic intraocular lens is fixated to the midperiphery of the iris.
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