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W Haigis

Publications and source records attributed to W Haigis.

20 records · Page 2Linked to original sources

Echo reference standards in ophthalmic ultrasonography.

The use of different echo standards in ophthalmic ultrasonography is discussed. The acoustical properties of the W38 Hema reflector made out of soft corneal contact lens material are determined and verified in several independent measurements. It is shown that this material meets the requirements for plane echo interfaces which are mandatory for reflectors considered to serve as echo standards. A conversion diagram is given for echo references presently used in ophthalmic ultrasonography. Finally, an example for an application of the W38 reflector in performance control and calibration measurements on ultrasonic instruments is presented.

Calibration↗

Bilateral cataract after phakic posterior chamber top hat-style silicone intraocular lens.

BACKGROUND: New strategies have been developed for surgical treatment of high myopia. Recently, implantation of minus power posterior chamber intraocular lenses (IOL) into phakic eyes has been introduced. METHODS: We report a 37 year-old female patient who developed bilateral anterior subcapsular cataract 7 years after minus-power, top hat-style silicone posterior chamber IOL implantation in Russia. The corrected visual acuity was right eye 20/200 and left eye 20/63. Because of the high myopia and the posterior chamber IOL in her phakic eyes, biometry for IOL calculation gave contradictory results. Both posterior chamber IOLs were found to be adherent to the crystalline lenses. After posterior chamber IOL explantation and phacoemulsification, intraoperative retinoscopy was performed. With this aphakic refraction, the IOL power was calculated and implanted. The explanted posterior chamber IOLs were examined by scanning electron microscopy. RESULTS: After bilateral operation the corrected visual acuity increased to right eye 20/32 and left eye 20/40, respectively. On scanning electron microscopy, a membranous structure of unknown origin was noted on the entire surface of the explanted posterior chamber IOLS. CONCLUSION: There is a potential risk of cataract formation after implantation of this top hat-style silicone posterior chamber IOL. If cataract extraction in this specific situation is needed, a different approach for calculating the aphakic IOL power is necessary, such as intraoperative retinoscopy.

Adult↗